All-solid-state battery

Abstract

An all-solid-state battery according to an embodiment includes a laminate including a positive electrode layer having a positive electrode current collector, a solid electrolyte layer, and a negative electrode layer, a first external electrode disposed outside the laminate and connected to the positive electrode layer, and a second external electrode disposed outside the laminate and connected to the negative electrode layer, in which the laminate includes an active region, in which the positive electrode layer, the solid electrolyte layer, and the negative electrode layer overlap in a first direction, and a margin region, which is a region between an outer surface of the laminate in a second direction intersecting the first direction and the active region, and the positive electrode current collector includes a first portion and a second portion connected to the first portion and having a thickness in the first direction greater than that of the first portion, and the first portion is disposed only in the active region and the second portion is disposed in the margin region.

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, ensuring the safety of batteries is required.

[0003] Lithium-ion batteries currently on the market use electrolyte solutions containing flammable organic solvents, so there is a risk of overheating and fire in the event of a short circuit. Accordingly, an all-solid-state battery using a solid electrolyte instead of an electrolyte solution has been proposed. Furthermore, all-solid-state batteries with high capacity retention rate even during high-speed charging and discharging are required.

[0004] The present disclosure attempts to provide an all-solid-state battery with high capacity retention rate even during high-speed charging and discharging.

[0005] However, the problems to be solved by embodiments of the present invention are not limited to the above-described problems, and can be variously expanded within the scope of the technical spirit included in the present invention.

[0006] An all-solid-state battery according to an embodiment includes a laminate including a positive electrode layer having a positive electrode current collector, a solid electrolyte layer, and a negative electrode layer, a first external electrode disposed outside the laminate and connected to the positive electrode layer, and a second external electrode disposed outside the laminate and connected to the negative electrode layer, in which the laminate includes an active region, in which the positive electrode layer, the solid electrolyte layer, and the negative electrode layer overlap in a first direction, and a margin region, which is a region between an outer surface of the laminate in a second direction intersecting the first direction and the active region, the positive electrode current collector includes a first portion, a second portion connected to the first portion and having a thickness in the first direction greater than that of the first portion, and the first portion is disposed only in the active region and the second portion is disposed in the margin region.

[0007] The second portion may be in contact with the solid electrolyte layer.

[0008] The second portion may include a first surface and a second surface opposing each other in the first direction, and the first surface and the second surface may be in contact with different solid electrolyte layers, respectively.

[0009] The thickness of the second portion may be 5 times or more and 9 times or less than the thickness of the first portion.

[0010] The positive electrode layer may include a positive electrode active material disposed on the first portion.

[0011] The first portion may include a third surface and a fourth surface opposing each other in the first direction, and the positive electrode active material may include a first positive electrode active material layer disposed on the third surface and a second positive electrode active material layer disposed on the fourth surface.

[0012] An average thickness of the first positive electrode active material layer may be 2.5 times or more and 6 times or less than an average thickness of the first portion, and an average thickness of the second positive electrode active material layer may be 2.5 times or more and 6 times or less than the average thickness of the first portion.

[0013] The second portion may have a first average width in the second direction, the margin region has a second average width in the second direction, and the first average width may be the same as the second average width.

[0014] The negative electrode layer may include a negative electrode current collector and a negative electrode active material.

[0015] An all-solid-state battery according to an embodiment includes a laminate including a positive electrode layer having a positive electrode current collector, a solid electrolyte layer, and a negative electrode layer, a first external electrode disposed outside the laminate and connected to the positive electrode layer, and a second external electrode disposed outside the laminate and connected to the negative electrode layer, in which the laminate includes an active region, in which the positive electrode layer, the solid electrolyte layer, and the negative electrode layer overlap in a first direction, and a margin region, which is a region between an outer surface of the laminate in a second direction intersecting the first direction and the active region, the positive electrode current collector includes a first portion disposed in the active region, and a second portion disposed in the margin region, connected to the first portion, and having a thickness in the first direction greater than that of the first portion, and the second portion is in contact with the solid electrolyte layer.

[0016] The second portion may include a first surface and a second surface opposing each other in the first direction, and the first surface and the second surface may be in contact with different solid electrolyte layers, respectively.

[0017] The thickness of the second portion may be 5 times or more and 9 times or less than the thickness of the first portion.

[0018] The positive electrode layer may include a positive electrode active material disposed on the first portion.

[0019] The first portion may include a third surface and a fourth surface opposing each other in the first direction, and the positive electrode active material may include a first positive electrode active material layer disposed on the third surface and a second positive electrode active material layer disposed on the fourth surface.

[0020] An average thickness of the first positive electrode active material layer may be 2.5 times or more and 6 times or less than an average thickness of the first portion, and an average thickness of the second positive electrode active material layer may be 2.5 times or more and 6 times or less than the average thickness of the first portion.

[0021] An all-solid-state battery according to an embodiment includes a laminate in which a positive electrode layer having a positive electrode current collector, a solid electrolyte layer, and a negative electrode layer are stacked in a first direction, a first external electrode disposed outside the laminate and connected to the positive electrode current collector, and a second external electrode disposed outside the laminate and connected to the negative electrode layer, in which the positive electrode current collector includes a second portion connected to the first external electrode and a first portion connected to the second portion and having a thickness in the first direction smaller than that of the second portion, and a positive electrode active material layer is disposed on a surface of the first portion, and the positive electrode active material layer is spaced apart from the first external electrode in a second direction intersecting the first direction.

[0022] The thickness of the second portion may be 5 times or more and 9 times or less than the thickness of the first portion.

[0023] The first portion may include a third surface and a fourth surface opposing each other in the first direction, and the positive electrode active material layer may include a first positive electrode active material layer disposed on the third surface and a second positive electrode active material layer disposed on the fourth surface.

[0024] An average thickness of the first positive electrode active material layer may be 2.5 times or more and 6 times or less than an average thickness of the first portion, and an average thickness of the second positive electrode active material layer may be 2.5 times or more and 6 times or less than the average thickness of the first portion.

[0025] The second portion may be in contact with the solid electrolyte layer.

[0026] The all-solid-state battery according to an embodiment can have a high capacity retention rate even during high-speed charging and discharging.

[0027] FIG. 1 is a perspective view schematically showing an all-solid-state battery according to an embodiment.

[0028] FIG. 2 is a perspective view schematically showing a laminate of FIG. 1.

[0029] FIG. 3 is a cross-sectional view taken along line I-I' of FIG. 1.

[0030] FIG. 4 is a partially enlarged cross-sectional view schematically showing a structure of a positive electrode layer of the all-solid-state battery of FIG. 1.

[0031] FIG. 5 is a partial cross-sectional view schematically showing a thin portion of the positive electrode layer of the all-solid-state battery of FIG. 1.

[0032] FIG. 6 is a partial cross-sectional view schematically showing a negative electrode layer of the all-solid-state battery of FIG. 1.

[0033] In the following detailed description, only certain embodiments of the present invention have been shown and described, simply by way of illustration. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. Further, some constituent elements in the drawing may be exaggerated, omitted, or schematically illustrated, and a size of each constituent element does not reflect the actual size entirely.

[0034] The accompanying drawings are provided for helping to easily understand embodiments disclosed in the present specification, and the technical spirit disclosed in the present specification is not limited by the accompanying drawings, and it will be appreciated that the present invention includes all of the modifications, equivalent matters, and substitutes included in the spirit and the technical scope of the present invention.

[0035] Terms including an ordinary number, such as first and second, are used for describing various constituent elements, but the constituent elements are not limited by the terms. The terms are used only to discriminate one constituent element from another constituent element.

[0036] Further, 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 "on" a reference portion, the element is located above or below the reference portion, and it does not necessarily mean that the element is located "above" or "on" in a direction opposite to gravity.

[0037] Throughout the specification, it will be appreciated that terms "including" and "having" are intended to designate the existence of characteristics, numbers, steps, operations, constituent elements, and components described in the specification or a combination thereof, and do not exclude a possibility of the existence or addition of one or more other characteristics, numbers, steps, operations, constituent elements, and components, or a combination thereof in advance. 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.

[0038] Further, in the entire specification, when it is referred to as "on a plane", it means when a target part is viewed from above, and when it is referred to as "on a cross-section", it means when the cross-section obtained by cutting a target part vertically is viewed from the side.

[0039] Further, throughout the specification, when it is referred to as "connected", this does not only mean that two or more constituent elements are directly connected, but may mean that two or more constituent elements are indirectly connected through another constituent element, are physically connected, electrically connected, or are integrated even though two or more constituent elements are referred as different names depending on a location and a function.

[0040] FIG. 1 is a perspective view schematically showing an all-solid-state battery according to an embodiment, FIG. 2 is a perspective view schematically showing a laminate of FIG. 1, and FIG. 3 is a cross-sectional view taken along line I-I' of FIG. 1. FIG. 4 is a partially enlarged cross-sectional view schematically showing a structure of a positive electrode layer of the all-solid-state battery of FIG. 1. In addition, FIG. 5 is a partial cross-sectional view schematically showing a thin portion of the positive electrode layer of the all-solid-state battery of FIG. 1, and FIG. 6 is a partial cross-sectional view schematically showing a negative electrode layer of the all-solid-state battery of FIG. 1.

[0041] Referring to FIGS. 1 and 2, an all-solid-state battery 1000 includes a laminate 100, a first external electrode 300, and a second external electrode 400.

[0042] First, as for directions defined for describing the present embodiment, an L-axis, a W-axis, and a T-axis shown in the drawings indicate axes representing a length direction, a width direction, and a thickness direction of the all-solid-state battery 1000, respectively.

[0043] The thickness direction (T-axis direction) may be a direction perpendicular to a wide surface (major surface) of sheet-shaped components. For example, the thickness direction (T-axis direction) may be used as the same concept as a direction in which components of a laminate 100 are stacked.

[0044] The length direction (L-axis direction) is a direction parallel to the wide surface (major surface) of the sheet-shaped components and may be a direction that intersects with (or is orthogonal to) the thickness direction (T-axis direction). For example, the length direction (L-axis direction) may be a direction in which the first external electrode 300 and the second external electrode 400 oppose each other.

[0045] The width direction (W-axis direction) is a direction parallel to the wide surface (major surface) of sheet-shaped components and may be a direction that intersects (or is orthogonal to) both the thickness direction (T-axis direction) and the length direction (L-axis direction).

[0046] The laminate 100 may have a substantially hexahedral shape, but the present embodiment is not limited thereto. Due to shrinkage during sintering, the laminate 100 may not have a perfect hexahedral shape, but may have a substantially hexahedral shape. For example, the laminate 100 has a substantially rectangular parallelepiped shape, but portions corresponding to corners or vertices may have a rounded shape.

[0047] In the present embodiment, for convenience of description, surfaces opposing each other in the length direction (L-axis direction) of the laminate 100 are defined as a first surface S1 and a second surface S2, surfaces opposing each other in the width direction (W-axis direction) of the laminate 100 and connecting the first surface S1 and the second surface S2 are defined as a third surface S3 and a fourth surface S4, and surfaces opposing each other in the thickness direction (T-axis direction) of the laminate 100 and connecting the first surface S1 and the second surface S2 are defined as a fifth surface S5 and a sixth surface S6.

[0048] Accordingly, a first direction, in which the first surface S1 and the second surface S2 oppose each other may be the length direction (L-axis direction), and a second direction and a third direction perpendicular to the first direction and perpendicular to each other may be the thickness direction (T-axis direction) and the width direction (W-axis direction), or the width direction (W-axis direction) and the thickness direction (T-axis direction), respectively.

[0049] A length of the laminate 100 may refer to, based on an optical microscope or scanning electron microscope (SEM) image of a cross-section taken along the length direction (L-axis direction) and the thickness direction (T-axis direction) at a central portion of the laminate 100 in the width direction (W-axis direction), a maximum value among lengths of a plurality of line segments that connect two outermost boundary lines opposing each other in the length direction (L-axis direction) of the laminate 100 shown in the above-described cross-sectional image and are parallel to the length direction (L-axis direction). Meanwhile, the length of the laminate 100 may refer to a minimum value among lengths of a plurality of line segments that connect two outermost boundary lines opposing each other in the length direction (L-axis direction) of the laminate 100 shown in the above-described cross-sectional image and are parallel to the length direction (L-axis direction). On the other hand, the length of the laminate 100 may refer to an arithmetic average value of lengths of at least two line segments among the plurality of line segments that connect two outermost boundary lines opposing each other in the length direction (L-axis direction) of the laminate 100 shown in the above-described cross-sectional image and are parallel to the length direction (L-axis direction).

[0050] A thickness of the laminate 100 may refer to, based on an optical microscope or scanning electron microscope (SEM) photograph of a cross-section in the length direction (L-axis direction) - the thickness direction (T-axis direction) at the center of the width direction (W-axis direction) of the laminate 105, a maximum value among lengths of the plurality of line segments that connect two outermost boundary lines opposing each other in the thickness direction (T-axis direction) of the laminate 100 shown in the above-described cross-sectional photograph and are parallel to the thickness direction (T-axis direction). Meanwhile, the thickness of the laminate 100 may mean a minimum value among lengths of the plurality of line segments that connect two outermost boundary lines opposing each other in the thickness direction (T-axis direction) of the laminate 100 shown in the above-described cross-sectional photograph and are parallel to the thickness direction (T-axis direction). On the other hand, the thickness of the laminate 105 may mean an arithmetic average value of lengths of at least two line segments among the plurality of line segments that connect two outermost boundary lines opposing each other in the thickness direction (T-axis direction) of the laminate 100 shown in the above-described cross-sectional photograph and are parallel to the thickness direction (T-axis direction).

[0051] A width of the laminate 100 may refer to, based on an optical microscope or scanning electron microscope (microscope SEM) photograph of a cross-section in the length direction (L-axis direction)-the width direction (W-axis direction) at a central portion of the laminate 100 in the thickness direction (T-axis direction), a maximum value among lengths of the plurality of line segments that connect two outermost boundary lines opposing each other in the width direction (W-axis direction) of the laminate 100 shown in the above-described cross-sectional photograph and are parallel to the width direction (W-axis direction). Meanwhile, the width of the laminate 100 may mean a minimum value among lengths of the plurality of line segments that connect two outermost boundary lines opposing each other in the width direction (W-axis direction) of the laminate 100 shown in the above-described cross-sectional photograph and are parallel to the width direction (W-axis direction). On the other hand, the width of the laminate 100 may mean an arithmetic average value of lengths of at least two line segments among the plurality of line segments that connect two outermost boundary lines opposing each other in the width direction (W-axis direction) of the laminate 100 shown in the above-described cross-sectional photograph and are parallel to the width direction (W-axis direction).

[0052] Referring to FIGS. 2 to 6, the laminate 100 may include a solid electrolyte layer 110, a positive electrode layer 130, a negative electrode layer 150, an upper protective layer 160, a lower protective layer 170, and a margin layer 180.

[0053] The solid electrolyte layer 110, the positive electrode layer 130, and the negative electrode layer 150 may each be plural. The positive electrode layer 130 and the negative electrode layer 150 may be alternately stacked in the thickness direction (T-axis direction) with the solid electrolyte layer 110 interposed therebetween. Such a stacked structure may be repeated in the laminate 100, and the electrode layer closest to the fifth surface S5 of the laminate 100 may be the positive electrode layer 130 or the negative electrode layer 150, and the electrode layer closest to the sixth surface S6 may be the negative electrode layer 150 or the positive electrode layer 130.

[0054] The positive electrode layer 130 may be disposed on one surface of the solid electrolyte layer 110, and the negative electrode layer 150 may be disposed on the other surface of the solid electrolyte layer 110.

[0055] The solid electrolyte layer 110 includes a solid electrolyte. The solid electrolyte may serve as a passage for lithium (Li) ions.

[0056] The solid electrolyte included in the solid electrolyte layer 110 may include a glass-ceramic-based electrolyte including lithium halide (LiX, X is a halogen element such as F, Br, Cl, or I). The glass-ceramic (or crystallization glass) refers to a crystallographic mixture of amorphous and crystalline materials from which peaks and halos are observed in X-ray diffraction, electron beam diffraction, etc. Thus, the glass-ceramic-based electrolyte is an electrolyte that has undergone partial crystallization through sintering and in which amorphous and crystalline materials are mixed.

[0057] The glass-ceramic-based electrolyte may include a mixture of an amorphous material and two or more types of crystalline materials. In addition, the crystalline material included in the glass-ceramic-based electrolyte may include a lithium compound crystalline phase containing lithium.

[0058] When the glass-ceramic-based electrolyte is part of the solid electrolyte layer 110, sufficient densification is achieved after sintering, whereby it is possible to realize high ionic conductivity.

[0059] The glass-ceramic-based electrolyte may include 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). As a specific example, the glass-ceramic -based electrolyte may include a lithium chloroboracite-based electrolyte doped with aluminum, and as a specific example, the glass-ceramic-based electrolyte may include Li2O-B2O3-LiCl-Al2O3or Li4B4Al3O12Cl.

[0060] As another example, the solid electrolyte in the solid electrolyte layer 110 may contain a lithium-borosilicate-based electrolyte (hereinafter, referred to as LBSO-based electrolyte). The LBSO-based electrolyte is a glass-state electrolyte, and glass refers to a crystallographically amorphous material, from which halos are observed in the X-ray diffraction or electron beam diffraction.

[0061] When the LBSO-based electrolyte is part of the solid electrolyte layer 110, it is possible to keep the amorphous state during sintering while lowering the sintering temperature.　 Thus, there is an advantage that it is possible to realize high ionic conductivity, and reactivity with the electrode is not high. The LBSO-based electrolyte may include lithium (Li), boron (B), silicon (Si), aluminum (Al), phosphorus (P), germanium (Ge), and sulfur (S).

[0062] Alternatively, the solid electrolyte included in the solid electrolyte layer 110 may be one or more types selected from the group consisting of a Garnet-type, a Na super ionic conductor (NASICON)-type, a lithium super ionic conductor (LISICON)-type, a Perovskite-type, and a lithium phosphorus oxynitride (LiPON)-type.

[0063] In an area where the margin layer 180 to be described later is disposed, there may be a material with low ionic conductivity and low electrical conductivity, that is, an insulating material, or a material with ionic conductivity (or electrical conductivity) similar to that of the solid electrolyte. For example, when the material having ionic conductivity (or electrical conductivity) similar to that of the solid electrolyte is present in this area, the material may be the same material as the solid electrolyte in the other region or may be a different material. As another example, the material having ionic conductivity (or electrical conductivity) similar to that of the solid electrolyte and the insulating material may coexist in this area.

[0064] The Garnet-type solid electrolyte may refer to lithium lanthanum zirconium oxide (LLZO) represented by LiaLabZrcO12such as Li7La3Zr2O12, and the NASICON-type solid electrolyte may include lithium-aluminum-titanium-phosphate (LATP) of Li1+xAlxTi2-x(PO4)3(wherein 0<x<1) produced by introducing Ti to Li1+xAlxM2-x(PO4)3(LAMP) (wherein 0<x<2, M is Zr, Ti, or Ge)-type compound, lithium-aluminum-germanium-phosphate (LAGP) represented by Li1+xAlxGe2-x(PO4)3(wherein 0<x<1), such as Li1.3Al0.3Ge1.7(PO4)3containing an excessive amount of lithium, and / or lithium-zirconium-phosphate (LZP) of LiZr2(PO4)3.

[0065] In addition, the LISICON-type solid electrolyte may include solid solution oxide represented by xLi3AO4-(1-x)Li4BO4(wherein A is P, As, V, etc., and B is Si, Ge, Ti, etc.), such as Li4Zn(GeO4)4, Li10GeP2O12(LGPO), Li3.5Si0.5P0.5O4, and Li10.42Si(Ge)1.5P1.5Cl0.08O11.92, etc., and solid solution sulfide represented by Li4-xM1-yM'yS4(wherein M is Si or Ge and M' is P, Al, Zn, or Ga), such as Li2S-P2S5, Li2S-SiS2, Li2S-SiS2-P2S5, or Li2S-GeS2.

[0066] Furthermore, the Perovskite-type solid electrolyte may include lithium lanthanum titanate (LLTO) represented by Li3xLa2 / 3-x□1 / 3-2xTiO3(wherein 0<x<0.16, and □ is vacancy), such as Li1 / 8La5 / 8TiO3, and the LiPON-type solid electrolyte may include nitride such as lithium phosphorous oxynitride of Li2.8PO3.3N0.46.

[0067] The positive electrode layer 130 may be exposed from the first surface S1 of the laminate 100, and may be connected to the first external electrode 300.

[0068] Referring to FIGS. 3 to 5, the positive electrode layer 130 may include a positive electrode current collector 133, a first positive electrode active material layer 135, and a second positive electrode active material layer 136.

[0069] The positive electrode current collector 133 may be made of, for example, a plate-shaped member or a thin member. As another example, the positive electrode current collector 133 may be a porous body having a reticulate shape, a mesh shape, or the like.

[0070] The positive electrode current collector 133 may include, but is not limited to, a porous metal plate made of stainless steel, nickel (Ni), copper (Cu), tin (Sn), aluminum (Al), or an alloy thereof.

[0071] In addition, the positive electrode current collector 133 may be coated with an oxidation-resistant metal or an oxidation-resistant alloy film to prevent oxidation.

[0072] The positive electrode current collector 133 may include a carbon-based plate-shaped, thin, or linear member. The positive electrode current collector 133 may include a conductive carbon material. The conductive carbon material may include graphite, conductive fiber such as carbon nanotube (CNT) or vapor grown carbon fiber (VGCF), or conductive carbon such as carbon black.

[0073] Meanwhile, the positive electrode current collector may also include one or more types of solid electrolytes.

[0074] Referring to FIG. 3, the laminate 100 may include an active region A, a first margin region M1, and a second margin region M2.

[0075] The active region A is a region where the positive electrode layer 130, the solid electrolyte layer 110, and the negative electrode layer 150 overlap in the thickness direction (T-axis direction).

[0076] The first margin region M1 is a region between the active region A and the first surface S1 of the laminate 100, and the second margin region M2 is a region between the active region A and the second surface S2 of the laminate 100.

[0077] In the active region A, the positive electrode layer 130, the solid electrolyte layer 110, and the negative electrode layer 150 are all present.

[0078] In the first margin region M1, the positive electrode layer 130, the solid electrolyte layer 110, and the margin layer 180 are present, and in the second margin region M2, the negative electrode layer 150, the solid electrolyte layer 110, and the margin layer 180 are present. That is, no negative electrode layer 150 is present in the first margin region M1, and no positive electrode layer 130 is present in the second margin region M2.

[0079] Referring to FIGS. 3 and 4, the positive electrode current collector 133 may include two portions of different thicknesses. That is, the positive electrode current collector 133 may include a thick portion 133M and a thin portion 133K connected to the thick portion 133M. The thick portion 133M is disposed in the first margin region M1, and the thin portion 133K is disposed in the active region A. For example, the thin portion 133K may be disposed only in the active region A. In some embodiments, the thin portion 133K may be referred to as a first portion and the thick portion 133M may be referred to as a second portion.

[0080] The thick portion 133M has a first thickness t1, and the thin portion 133K has a second thickness t2. The first thickness t1 may be greater than the second thickness t2. That is, the thickness at any location of the thick portion 133M may be greater than the thickness of the thin portion 133K. That is, the minimum value of the first thickness t1 may be greater than the maximum value of the second thickness t2. Not only for a configuration in which the thickness of the thick portion 133M changes rapidly relative to the thickness of the thin portion 133K, but also for a configuration in which the thickness of the thick portion 133M changes gradually and continuously, or in a stepwise manner, or in a combination thereof, the thickness of the thick portion at any location is thicker than that of the thin portion.

[0081] The first thickness t1 may be five (5) times or more and nine (9) times or less than the second thickness t2.

[0082] If the first thickness t1 is less than 5 times the second thickness t2, there may be an undesirable effect of decreasing capacity as the charging speed increases. If the first thickness t1 exceeds 9 times the second thickness t2, the positive electrode current collector may become thicker than the positive electrode active material, which may deform the shape of a chip and may cause shape unevenness in an all-solid-state battery manufactured by stacking the positive electrode layer, the negative electrode layer, and the solid electrolyte layer in multiple layers. This may result in deformations such as ‘wave phenomenon’ in the positive electrode layer and the negative electrode layer during the co-sintering process.

[0083] For example, the first thickness t1 may be 15.5 um and the second thickness t2 may be 3.0 um. As another example, the first thickness t1 may be 21.7 um and the second thickness t2 may be 3.4 um.

[0084] Here, the first thickness and the second thickness may refer to the thicknesses of the thick portion and the thin portion of the same positive electrode current collector. The first thickness and the second thickness may be measured based on a scanning electron microscope (SEM) image at 10,000x magnification of a cross-section taken along the length direction (L-axis direction) and the thickness direction (T-axis direction) at the central portion of the laminate in the width direction (W-axis direction). That is, the first thickness and the second thickness may be measurements of the thicknesses of the thick portion 133M and the thin portion 133K, respectively, of any one of the positive electrode current collectors shown in the above-described cross-sectional image.

[0085] According to the present embodiment, the positive electrode current collector 133 includes the thick portion 133M that is thicker than the thin portion 133K, so that electron transfer may occur smoothly. Furthermore, since the thick portion 133M is connected to the first external electrode 300, a contact resistance between the positive electrode layer 130 and the first external electrode 300 may be reduced.

[0086] In contrast to the present embodiment, if the positive electrode current collector consists of only a thin portion, electron transfer may not be as smooth. This is because the thickness of the positive electrode current collector is too thin (e.g., 3 um or less).

[0087] The thick portion 133M has a first width w1. The first width w1 is a value measured in the length direction (L-axis direction) within the first margin region M1.

[0088] The first margin region M1 has a second width w2. The second width w2 is a width of the first margin region M1 measured in the length direction (L-axis direction).

[0089] The first width w1 may be the same as the second width w2.

[0090] Here, the first width w1 and the second width w2 may be average values. That is, the first width w1 and the second width w2 may be measured based on a scanning electron microscope (SEM) image at 10,000x magnification of a cross-section taken along the length direction (L-axis) and the thickness direction (T-axis direction) at the central portion of the laminate in the width direction (W-axis direction). The first width w1 may be an arithmetic mean value of a width of the thick portion measured at the uppermost point, a width of the thick portion measured at the lowermost point, and a width of the thick portion measured at the center in the thickness direction (T-axis direction) of the laminate shown in the above-described cross-sectional image. Additionally, the second width may be an arithmetic mean value of a distance between a first surface of the laminate and a longitudinal end portion of the negative electrode layer opposite to the first surface measured at the uppermost point of the laminate, a distance between the first surface of the laminate and a longitudinal end portion of the negative electrode layer opposite to the first surface measured at the lowermost point, and a distance between the first surface of the laminate and a longitudinal end portion of the negative electrode layer opposite to the first surface measured at the center shown in the above-described cross-sectional image.

[0091] The positive electrode current collector 133 may include a first surface 133a and a second surface 133b in the first margin region M1. That is, the thick portion 133M may include the first surface 133a and the second surface 133b. The first surface 133a and the second surface 133b oppose each other in the thickness direction (T-axis direction).

[0092] The first surface 133a of the positive electrode current collector 133 is in contact with the solid electrolyte layer 110, and the second surface 133b is in contact with another solid electrolyte layer 110. That is, the thick portion 133M may be disposed to be in contact with two different solid electrolyte layers simultaneously. In other words, no positive electrode active material layer may be disposed on a surface of the positive electrode current collector 133 in the first margin region M1.

[0093] Referring to FIG. 5, the positive electrode current collector 133 may include a third surface 133c and a fourth surface 133d in the active region A. That is, the thin portion 133K may include the third surface 133c and the fourth surface 133d. The third surface 133c and the fourth surface 133d oppose each other in the thickness direction (T-axis direction).

[0094] The first positive electrode active material layer 135 and the second positive electrode active material layer 136 may include positive electrode active materials and may be disposed on a surface of the thin portion 133K.

[0095] The first positive electrode active material layer 135 and the second positive electrode active material layer 136 may not be disposed on the surface of the thick portion 133M. In this case, the first positive electrode active material layer 135 and the second positive electrode active material layer 136 may be spaced apart from the first external electrode 300 in the length direction (L-axis direction). Therefore, the first external electrode 300 is connected to the positive electrode current collector 133 but not connected to the first positive electrode active material layer 135 and the second positive electrode active material layer 136. When the positive electrode layer 130 is connected to the first external electrode 300, it may mean that the thick portion 133M of the positive electrode current collector 133 is connected to the first external electrode 300.

[0096] The first positive electrode active material layer 135 and the second positive electrode active material layer 136 may be formed by printing a positive electrode active material on one or both surfaces of the thin portion 133K, but the method of forming the positive electrode active material layers is not limited thereto.

[0097] Here, the thickness of the first positive electrode active material layer 135 may be 2.5 times or more and 6 times or less than the thickness t2 of the thin portion 133K.

[0098] If the thickness of the first positive electrode active material layer 135 is less than 2.5 times the thickness of the thin portion 133K, the thickness is too thin, resulting in low energy density and reduced capacity, which in turn reduces the commercial value of the all-solid-state battery. If the thickness of the first positive electrode active material layer 135 exceeds 6 times the thickness of the thin portion 133K, the capacity reduction with the charging speed becomes significant and battery characteristics deteriorate.

[0099] The thickness of the second positive electrode active material layer 136 may also be 2.5 times or more and 6 times or less than the thickness t2 of the thin portion 133K.

[0100] If the thickness of the second positive electrode active material layer 136 is less than 2.5 times the thickness t2 of the thin portion 133K, the thickness is too thin, resulting low energy density and reduced capacity, which in turn reduces the commercial value of the all-solid-state battery. If the thickness of the second positive electrode active material layer 136 exceeds 6 times the thickness of the thin portion 133K, the capacity reduction with the charging speed becomes significant and battery characteristics deteriorate.

[0101] Here, the thickness of the positive electrode active material layer and the thickness of the thin portion may be an average thickness of the positive electrode active material layer and an average thickness of the thin portion of one positive electrode layer. The average thickness of the positive electrode active material layer and the average thickness of the thin portion may be measured based on a scanning electron microscope (SEM) image at 10,000x magnification of a cross-section taken along the length direction (L-axis direction) and the thickness direction (T-axis direction) at the central portion of the laminate in the width direction (W-axis direction). The average thickness of the positive electrode active material layer and the average thickness of the thin portion may be arithmetic mean values of the thicknesses of the positive electrode active material layer and the thin portion of one positive electrode layer shown in the above-described cross-sectional image, respectively, measured at thirty (30) equally spaced points in the length direction (L-axis direction). In this way, when the average thickness of the positive electrode active material layer and the average thickness of the thin portion are measured at ten (10) positive electrode layers, and then arithmetic average values of the measured values are derived, the average thickness of the positive electrode active material layer and the average thickness of the thin portion may be further generalized.

[0102] The positive electrode active material included in the positive electrode active material layers 135 and 136 may comprise a material containing lithium (Li) ions. The positive electrode active material may reversibly intercalate and deintercalate lithium ions. In other words, the positive active material may contain lithium ions and may serve to provide the lithium ions to the negative electrode when the all-solid-state battery is charging. The positive electrode active material may affect the capacity and output of an all-solid-state battery.

[0103] For example, the positive electrode active material may include at least one selected from the group consisting of compounds represented by the following formula: 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 chemical formula above, A is Ni, Co, or Mn; M is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Nb, Ti, 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; J is V, Cr, Mn, Co, Ni, or Cu.

[0104] The positive electrode active material may also include LiCoO2, LiMnxO2x(where x is 1 or 2), LiNi1-xMnxO2x(where 0 <x<1), LiNi1-x-yCoxMnyO2(where 0≤x≤0.5, 0≤y≤0.5), LiFePO4, TiS2, FeS2, TiS3, or FeS3, but is not limited thereto.

[0105] The positive electrode active material may optionally include a conductive material and a binder. However, because an organic substance such as a binder decomposes during sintering process, the organic material may not remain on the positive electrode active material layer of the obtained positive electrode current collector.

[0106] The conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the all-solid-state battery 1000. For example, graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjenblack®, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers, metal fibers, etc.; carbon fluoride; metal components such as lithium (Li), tin (Sn), aluminum (Al), nickel (Ni), copper (Cu), etc., oxides thereof, nitrides thereof, or fluorides thereof; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc., may be used.

[0107] The binder may be used to improve the bonding strength of the active material, the conductive material, or the like. The binder may include, but not limited to, at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluorine rubber, various copolymers, etc.

[0108] Meanwhile, the positive electrode layer 130 may further contain a solid electrolyte component. The solid electrolyte component may include one or more of the above-described components and may serve as an ionic conduction channel in the positive electrode layer. Therefore, it is possible to reduce interface resistance.

[0109] The negative electrode layer 150 may be exposed from the second surface S2 of the laminate 100, and may be connected to the second external electrode 400.

[0110] Referring to FIGS. 3, 4, and 6, the negative electrode layer 150 may include a negative electrode current collector 153, a first negative electrode active material layer 155, and a second negative electrode active material layer 156.

[0111] Meanwhile, the negative electrode layer 150 may not include a negative electrode current collector. In this case, the negative electrode layer may only consist of a negative electrode active material layer.

[0112] The negative electrode current collector 153 may be composed of, for example, a plate-shaped member or a thin member. Alternatively, the negative electrode current collector 153 may include a porous body having a reticulate shape, a mesh shape, or the like.

[0113] The negative electrode current collector 153 may include a first surface 153a and a second surface 153b. The first surface 153a and the second surface 153b oppose each other in the thickness direction (T-axis direction).

[0114] For example, the negative electrode current collector 153 may include, but not limited to, a porous metal plate made of stainless steel, nickel (Ni), copper (Cu), tin (Sn), aluminum (Al), or an alloy thereof.

[0115] In addition, the negative electrode current collector 153 may be coated with an oxidation-resistant metal or an oxidation-resistant alloy film to prevent oxidation.

[0116] The negative electrode current collector 153, like the positive electrode current collector 133, may include a conductive carbon-based material and one or more types of solid electrolytes. The negative electrode current collector 153 may be identical to the negative electrode active material layers 155 and 156.

[0117] The first negative electrode active material layer 155 and the second negative electrode active material layer 156 may include a negative electrode active material, and may be disposed on a surface of the negative electrode current collector 153. The first negative electrode active material layer 155 and the second negative electrode active material layer 156 may be formed by printing a negative electrode active material on one or both surfaces of the negative electrode current collector 153, but the method of forming the negative electrode active material layers is not limited thereto.

[0118] The negative electrode active material included in the negative electrode active material layers 155 and 156 may store the lithium ions that have moved from the positive electrode and release the lithium ions when the all-solid-state battery is discharged, thereby generating electrical energy. 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 may be used as the negative electrode active material. The negative electrode active material may contain a lithium metal and / or a lithium metal alloy.

[0119] The lithium metal alloy may contain lithium, and a metal / metalloid capable of making an alloy with lithium. For example, the metal / metalloid capable of forming an alloy with lithium may include Si, Sn, Al, Ge, Pb, Bi, Sb, and Si-AM alloy (wherein AM is an alkali metal, an alkaline earth metal, an element in group 13 to 16, a transition metal, a rare-earth element, or a combination thereof, and does not include Si), Sn-AM alloys (wherein AM is an alkali metal, an alkaline earth metal, an element in group 13 to 16, a transition metal, a transition metal oxide such as lithium titanium oxide (Li4Ti5O12), a rare-earth element, or combinations thereof, and does not include Sn), MnOx(wherein 0<x≤2), and the like.

[0120] The element AM may include 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 combinations thereof.

[0121] Additionally, the oxide of the metal / metalloid capable of forming an alloy with lithium may include lithium titanium oxide, vanadium oxide, lithium vanadium oxide, SnO2, SiOx(wherein 0<x<2), or the like. For example, the negative electrode active material may include one or more elements selected from the group consisting of the elements in group 13 to 16 of the periodic table of elements. For example, the negative electrode active material may contain one or more elements selected from the group consisting of Si, Ge, and Sn.

[0122] The carbon-based material may include crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may be graphite such as natural graphite or artificial graphite that is in a shapeless, disc-shaped, flake-shaped, globular, or fibrous form. In addition, the amorphous carbon may include, but not limited to, soft carbon (low-temperature calcined carbon), hard carbon, mesophase pitch carbide, calcined cokes, graphene, carbon black, fullerene soot, carbon nanotube, carbon fiber, etc.

[0123] The silicon may include at least one selected from the group consisting of Si, SiOx(wherein 0<x<2, for example, 0.5 to 1.5), Sn, SnO2, or silicon-containing metal alloy, and mixtures thereof. For example, the silicon-containing metal alloy may include silicon, and one or more of Al, Sn, Ag, Fe, Bi, Mg, Zn, In, Ge, Pb, or Ti.

[0124] The negative electrode active material may optionally include a conductive material and a binder.

[0125] The conductive material is not particularly limited as long as it provides conductivity without causing chemical changes in the all-solid-state battery 1000. For example, graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjenblack®, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers, metal fibers, etc.; carbon fluoride; metal components such as lithium (Li), tin (Sn), aluminum (Al), nickel (Ni), copper (Cu), etc., oxides thereof, nitrides thereof, or fluorides thereof; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc., may be used.

[0126] The binder may be used to improve the bonding strength of the active material, the conductive material, or the like. The binder may include, but not limited to, at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluorine rubber, various copolymers, etc.

[0127] Meanwhile, the negative electrode layer 150 may further contain a solid electrolyte component. The solid electrolyte component may contain one or more of the above-described components and may serve as an ionic conduction channel in the negative electrode layer. Thus, interface resistance can be reduced.

[0128] The upper protective layer 160 and the lower protective layer 170 may be outermost layers disposed on the fifth surface S5 and sixth surface S6 of the laminate 100, respectively. That is, the upper protective layer 160 may be the outermost layer disposed on the fifth surface S5 of the laminate 100, and the lower protective layer 170 may be the outermost layer disposed on the sixth surface S6 of the laminate 100. The upper protective layer 160 and lower protective layer 170 may improve moisture resistance reliability by preventing moisture infiltration and may prevent damage from physical and chemical impacts.

[0129] The upper protective layer 160 and the lower protective layer 170 may be an insulating layer made of an insulating material, that is, a material that is not electrically (ionically) conductive.

[0130] The upper protective layer 160 and the lower protective layer 170 may include a ceramic material, for example, 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), mixtures thereof, oxides thereof and / or nitrides thereof, or any other suitable ceramic material, but are not limited thereto. In addition, the upper protective layer 160 and the lower protective layer 170 may optionally include the above-described solid electrolyte, and may include one or more types of solid electrolytes, but are not limited thereto.

[0131] The margin layer 180 may be disposed along the edges of the positive electrode layer 130 and the negative electrode layer 150. The margin layer 180 may be disposed to be in contact with the remaining edges of the positive electrode layer 130, except where the positive electrode layer 130 is connected to the first external electrode 300. In addition, the margin layer 180 may be disposed to be in contact with the remaining edges of the negative electrode layer 150, except where the negative electrode layer 150 is connected to the second external electrode 400.

[0132] For example, the margin layer 180 may be disposed on the solid electrolyte layer 110 in a region other than the region where the positive electrode layer 130 or negative electrode layer 150 is disposed. When the positive electrode layer 130 is disposed on the solid electrolyte layer 110, the margin layer 180 may be disposed in a region other than the region where the positive electrode layer 130 is disposed. Likewise, when the negative electrode layer 150 is disposed on the solid electrolyte layer 110, the margin layer 180 may be disposed in a region other than the region where the negative electrode layer 150 is disposed.

[0133] Referring to FIG. 3, the margin layer 180 may comprise a portion of the first surface S1 and a portion of the second surface S2 of the laminate 100. Meanwhile, although not shown, the margin layer 180 may comprise a portion of the third surface S3 and a portion of the fourth surface S4 of the laminate 100.

[0134] The margin layer 180 may be disposed to compensate for a level difference between the solid electrolyte layer 110 and the positive electrode layer 130 and a level difference between the solid electrolyte layer 110 and the negative electrode layer 150. For example, the margin layer 180 may be disposed on the same plane as the positive electrode layer 130 and the negative electrode layer 150. The margin layer 180 may compensate for a level difference between the solid electrolyte layer 110 and the positive electrode layer 130 or a level difference between the solid electrolyte layer 110 and the negative electrode layer 150. This increases the density between the solid electrolyte layer 110 and the electrode layers, which may prevent interlayer delamination or warping caused by sintering during a process of manufacturing the all-solid-state battery.

[0135] Meanwhile, the margin layer 180 may include a material that is resistant to moisture and has low lithium (Li) ion conductivity. In this case, the margin layer 180 may protect the active material layers 135, 136, 155, and 156 from moisture infiltration, lithium (Li) ion leakage, and the like. For example, the margin layer 180 may include an insulating material or an electrolyte material, and may include a material with an ionic conductivity of 1.0x10-10S / cm or less.

[0136] The margin layer 180 may include an insulating material, that is, a material that is not electrically (ionically) conductive.

[0137] The margin layer 180 may include, but not limited to, at least one selected from the group consisting of ceramic materials, such as 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), mixtures thereof, oxides thereof and / or nitrides thereof, or any other suitable ceramic material, but is not limited thereto.

[0138] Meanwhile, the margin layer 180 may optionally include a solid electrolyte that is the same as or different from the solid electrolyte included in the above-described solid electrolyte layer, and may include one or more types of solid electrolytes, but is not limited thereto.

[0139] In addition, a material having a low ionic conductivity and electrical conductivity, such as an insulating material, may be present in the margin layer 180, or a material having an ionic conductivity (or electrical conductivity) similar to the ionic conductivity (or electrical conductivity) of a solid electrolyte may be present in the margin layer 180. For example, when a material having ionic conductivity (or electrical conductivity) similar to the ionic conductivity (or electrical conductivity) of the solid electrolyte is present in the margin layer, the material may be a material that is identical to or different from the solid electrolyte in other regions. In another example, a material having ionic conductivity (or electrical conductivity) similar to the ionic conductivity (or electrical conductivity) of the solid electrolyte and an insulating material may coexist in the margin layer.

[0140] The first external electrode 300 and the second external electrode 400 are disposed outside the laminate 100.

[0141] The first external electrode 300 is connected to the positive electrode layer 130 and the solid electrolyte layer 110 on the first surface S1 of the laminate 100. For example, the first external electrode 300 may cover the first surface S1 of the laminate 100, and the first external electrode 300 may extend onto the third surface S3, the fourth surface S4, the fifth surface S5, and the sixth surface S6 of the laminate 100 to partially cover the respective surfaces.

[0142] On the other hand, in other embodiments, the first external electrode 300 may extend onto at least one of the fifth surface S5 and the sixth surface S6 of the laminate 100 to partially cover the corresponding surface.

[0143] The first external electrode 300 may be formed by baking a conductive paste. For example, the conductive paste may include glass and a metal such as silver (Ag) or copper (Cu).

[0144] The second external electrode 400 is connected to the negative electrode layer 150 and the solid electrolyte layer 110 on the second surface S2 of the laminate 100. For example, the second external electrode 400 may cover the second surface S2 of the laminate 100, and the second external electrode 400 may extend onto the third surface S3, the fourth surface S4, the fifth surface S5, and the sixth surface S6 of the laminate 100 to partially cover the respective surfaces.

[0145] On the other hand, in other embodiments, the second external electrode 400 may extend onto at least one of the fifth surface S5 and the sixth surface S6 of the laminate 100 to partially cover the corresponding surface.

[0146] The second external electrode 400 may be formed by baking a conductive paste. For example, the conductive paste may include glass and a metal such as silver (Ag) or copper (Cu).

[0147] For example, the fifth surface S1 and the sixth surface S2 of the laminate 100 may be dipped in a conductive paste and blotted to form the first external electrode 300 and the second external electrode 400. As another example, a conductive paste may be applied to the first surface S1 and the second surface S2 of the laminate 100, respectively, to form the first external electrode 300 and the second external electrode 400. As still another example, a dry film obtained by drying the conductive paste may be transferred to the laminate 100 and then baked to form the first external electrode 300 and the second external electrode 400, but the method of forming the first external electrode 300 and the second external electrode 400 is not limited to the method described above. For example, the metal included in the conductive paste may include at least one of copper (Cu), nickel (Ni), tin (Sn), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), tungsten (W), titanium (Ti), lead (Pb) and an alloy thereof, but is not limited thereto.

[0148] [Preparation Example: Manufacture of All-Solid-State Battery]

[0149] A plurality of striped positive electrode layers were formed by printing on a solid electrolyte layer (green sheet) in the order of a positive electrode active material layer, a positive electrode current collector, and a positive electrode active material layer, and then filling the spaces between the positive electrode layers with an insulating material to form a positive electrode sheet.

[0150] A plurality of striped negative electrode layers were formed by printing a negative electrode active material layer on a solid electrolyte layer (green sheet), and then filling the spaces between the negative electrode layers with an insulating material to form a negative electrode sheet.

[0151] A green chip was formed by alternately stacking the positive and negative electrode sheets.

[0152] The green chip was cut to form a laminate.

[0153] The laminate was calcined at 450°C to 500°C in an air atmosphere.

[0154] After calcination, the laminate was sintered at 500°C to 700°C in air or nitrogen atmosphere.

[0155] An all-solid-state battery was manufactured by applying a conductive paste for an external electrode to the surface of the sintered laminate, and then sequentially placing the laminate in a curing oven at 50°C, 80°C, and 200°C for 30 minutes each, followed by cooling to form the external electrodes.

[0156] Here, all-solid-state batteries were prepared according to Examples 1 to 3 and Comparative Examples 1 to 6 by varying the thickness of the positive electrode active material layer and the thickness of the positive electrode current collector as shown in Table 1. Here, the thickness of the positive electrode active material layer refers to the thickness of the positive electrode active material layer disposed on one surface of the positive electrode current collector.

[0157] Thickness A (um) of positive electrode active material layerThickness (um) of positive electrode current collectort1 / t2A / t2Active region t2Margin region t1Example 18.23.015.55.22.7Example 212.13.421.76.44.0Example 317.03.430.48.95.7Comparative Example 18.33.01.50.52.8Comparative Example 212.23.61.80.54.1Comparative Example 317.04.42.20.55.7Comparative Example 423.28.04.00.57.7Comparative Example 523.23.436.110.67.7Comparative Example 66.13.015.55.22.0

[0158] [Experimental Example: Performance of All-Solid-State Battery]

[0159] Five all-solid-state batteries of Examples 1 to 3 and Comparative Examples 1 to 6 were manufactured for each, and the capacity retention rate at each C-rate (current rate) was measured for one representative sample. The results are shown in Table 2 and FIG. 9.

[0160] Capacity retention rate (%)C-rate0.05C0.2C0.5C0.8 CExample 1100898885Example 2100878578Example 3100858372Comparative Example 1100757162Comparative Example 2100696661Comparative Example 3100504332Comparative Example 4100453019Comparative Example 5100604535Comparative Example 6100898886

[0161] Referring to Table 2, the capacity retention rate of the all-solid-state batteries manufactured according to Examples 1 to 3 decreased as the C-rate increased, but still showed a capacity retention rate of 72% or more at 0.8C. The capacity retention rate of the all-solid-state batteries manufactured according to Comparative Examples 1 to 4 decreased rapidly with increasing C-rate, with a minimum of 19% and a maximum of 62% at 0.8C. This result appears to be due to the fact that the positive electrode current collectors of the all-solid-state batteries manufactured according to Comparative Examples 1 to 4 consisted of only a thin portion of a small thickness. Meanwhile, in the all-solid-state battery manufactured according to Comparative Example 5, the capacity retention rate also decreased rapidly with increasing C-rate. This may seem to be because of the shape deformation of the all-solid-state battery as the first thickness t1 exceeded 9 times the second thickness t2, which affected the capacity retention rate. Meanwhile, in the all-solid-state battery manufactured according to Comparative Example 6, the capacity retention rate did not decrease rapidly with increasing C-rate, but the energy density was low because the thickness of the positive electrode active material layer was too thin. While the disclosure has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1.An all-solid-state battery comprising:a laminate comprising a positive electrode layer having a positive electrode current collector, a solid electrolyte layer, and a negative electrode layer;a first external electrode disposed outside the laminate and connected to the positive electrode layer; anda second external electrode disposed outside the laminate and connected to the negative electrode layer, whereinthe laminate comprisesan active region, in which the positive electrode layer, the solid electrolyte layer, and the negative electrode layer overlap in a first direction, anda margin region, which is a region between an outer surface of the laminate in a second direction intersecting the first direction and the active region, andwherein the positive electrode current collector comprises a first portion and a second portion, the second portion connected to the first portion and having a thickness in the first direction greater than that of the first portion, andwherein the first portion is disposed only in the active region and the second portion is disposed in the margin region.2.The all-solid-state battery of claim 1, wherein:the second portion is in contact with the solid electrolyte layer.3.The all-solid-state battery of claim 2, wherein:the second portion comprises a first surface and a second surface opposing each other in the first direction, andthe first surface and the second surface are in contact with different solid electrolyte layers, respectively.4.The all-solid-state battery of claim 1, wherein:the thickness of the second portion is 5 times or more and 9 times or less than the thickness of the first portion.5.The all-solid-state battery of claim 1, wherein:the positive electrode layer comprises a positive electrode active material disposed on the first portion.6.The all-solid-state battery of claim 5, wherein:the first portion comprises a third surface and a fourth surface opposing each other in the first direction, andthe positive electrode active material comprises a first positive electrode active material layer disposed on the third surface and a second positive electrode active material layer disposed on the fourth surface.7.The all-solid-state battery of claim 5, wherein:an average thickness of the first positive electrode active material layer is 2.5 times or more and 6 times or less than an average thickness of the first portion, andan average thickness of the second positive electrode active material layer is 2.5 times or more and 6 times or less than the average thickness of the first portion.8.The all-solid-state battery of claim 1, wherein:the second portion has a first average width in the second direction,the margin region has a second average width in the second direction, andthe first average width is the same as the second average width.9.The all-solid-state battery of claim 1, wherein:the negative electrode layer comprises a negative electrode current collector and a negative electrode active material.10.An all-solid-state battery comprising:a laminate comprising a positive electrode layer having a positive electrode current collector, a solid electrolyte layer, and a negative electrode layer;a first external electrode disposed outside the laminate and connected to the positive electrode layer, anda second external electrode disposed outside the laminate and connected to the negative electrode layer, whereinthe laminate comprisesan active region, in which the positive electrode layer, the solid electrolyte layer, and the negative electrode layer overlap in a first direction, anda margin region, which is a region between an outer surface of the laminate in a second direction intersecting the first direction and the active region,the positive electrode current collector comprisesa first portion disposed in the active region, anda second portion disposed in the margin region, connected to the first portion, and having a thickness in the first direction greater than that of the first portion, andthe second portion is in contact with the solid electrolyte layer.11.The all-solid-state battery of claim 10, whereinthe second portion comprises a first surface and a second surface opposing each other in the first direction, andthe first surface and the second surface are in contact with different solid electrolyte layers, respectively.12.The all-solid-state battery of claim 10, whereinthe thickness of the second portion is 5 times or more and 9 times or less than the thickness of the first portion.13.The all-solid-state battery of claim 10, whereinthe positive electrode layer comprises a positive electrode active material disposed on the first portion.14.The all-solid-state battery of claim 13, whereinthe first portion comprises a third surface and a fourth surface opposing each other in the first direction, andthe positive electrode active material comprises a first positive electrode active material layer disposed on the third surface and a second positive electrode active material layer disposed on the fourth surface.15.The all-solid-state battery of claim 14, whereinan average thickness of the first positive electrode active material layer is 2.5 times or more and 6 times or less than an average thickness of the first portion, andan average thickness of the second positive electrode active material layer is 2.5 times or more and 6 times or less than the average thickness of the first portion.16.An all-solid-state battery comprising:a laminate in which a positive electrode layer having a positive electrode current collector, a solid electrolyte layer, and a negative electrode layer are stacked in a first direction,a first external electrode disposed outside the laminate and connected to the positive electrode current collector, anda second external electrode disposed outside the laminate and connected to the negative electrode layer, whereinthe positive electrode current collector comprisesa second portion connected to the first external electrode, anda first portion connected to the second portion and having a thickness in the first direction smaller than that of the second portion, andwherein a positive electrode active material layer is disposed on a surface of the first portion, and the positive electrode active material layer is spaced apart from the first external electrode in a second direction intersecting the first direction.17.The all-solid-state battery of claim 16, whereinthe thickness of the second portion is 5 times or more and 9 times or less than the thickness of the first portion.18.The all-solid-state battery of claim 16, whereinthe first portion comprises a third surface and a fourth surface opposing each other in the first direction, andthe positive electrode active material layer comprises a first positive electrode active material layer disposed on the third surface and a second positive electrode active material layer disposed on the fourth surface.19.The all-solid-state battery of claim 18, whereinan average thickness of the first positive electrode active material layer is 2.5 times or more and 6 times or less than an average thickness of the first portion, andan average thickness of the second positive electrode active material layer is 2.5 times or more and 6 times or less than the average thickness of the first portion.20.The all-solid-state battery of claim 16, wherein,the second portion is in contact with the solid electrolyte layer.

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