All-solid-state battery

Abstract

An all-solid-state battery includes a laminate comprising a solid electrolyte layer, a positive electrode active material layer in contact with one surface of the solid electrolyte layer, and a negative electrode active material layer in contact with the other surface of the solid electrolyte layer. The battery is characterized in that a ratio of the sum of the thicknesses of the positive electrode active material layer and the negative electrode active material layer to the thickness of the solid electrolyte layer is greater than 0.5 and less than 5.8. The thickness of the solid electrolyte layer exceeds 5 μm, enhancing the charge and discharge performance while minimizing short-circuit risks.

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 downsized and used for extended periods, high-capacity batteries are needed, and battery safety is increasingly important due to the popularization of wearable electronic devices. Since currently commercially available lithium-ion batteries use an electrolyte containing a flammable organic solvent, there is a possibility of overheating and fire when a short circuit occurs. Accordingly, an all-solid-state battery using a solid electrolyte instead of an electrolyte solution has been proposed. Furthermore, an all-solid-state battery having rapid charging and discharging speed is on demand.

[0003] The present disclosure attempts to provide an all-solid-state battery having rapid charging and discharging speed.

[0004] However, the objective of the present disclosure is not limited to the aforementioned goal, and may be extended in various ways within the spirit and scope of the present disclosure.

[0005] An all-solid-state battery may include a laminate including a solid electrolyte layer, a positive electrode active material layer in contact with one surface of the solid electrolyte layer, and a negative electrode active material layer in contact with the other surface of the solid electrolyte layer, where a value obtained by dividing a sum of a thickness of the positive electrode active material layer and a thickness of the negative electrode active material layer by a thickness of the solid electrolyte layer may be greater than 0.5 and less than 5.8, and the thickness of the solid electrolyte layer may exceed 5 μm.

[0006] The solid electrolyte layer may include a solid electrolyte having an ionic conductivity of 10-4S / cm.

[0007] The solid electrolyte may comprise lithium-lanthanum-zirconium-oxide (LLZO).

[0008] The thickness of the solid electrolyte layer may be 6.2 μm or more and 19.8 μm or less.

[0009] The thickness of the positive electrode active material layer may be 3.0 μm or more and 24.5 μm or less.

[0010] The thickness of the negative electrode active material layer may be 2.4 μm or more and 13.5 μm or less.

[0011] A value obtained by dividing a sum of the thickness of the positive electrode active material layer and the thickness of the negative electrode active material layer by the thickness of the solid electrolyte layer may be greater than 0.8 and less than or equal to 2.7.

[0012] The solid electrolyte layer may include a solid electrolyte with an ionic conductivity of 10-6S / cm.

[0013] The solid electrolyte may comprise a lithium chloroboracite-based electrolyte doped with aluminum.

[0014] The thickness of the solid electrolyte layer may be 6.0 μm or more and 14.8 μm less.

[0015] The thickness of the positive electrode active material layer may be 3.2 μm or more and 13.5 μm or less.

[0016] The thickness of the negative electrode active material layer may be 2.5 μm or more and 8.7 μm or less.

[0017] According to an all-solid-state battery according to an embodiment, charging and discharging speed may be increased.

[0018] FIG. 1 is a perspective view schematically showing an all-solid-state battery according to an embodiment.

[0019] FIG. 2 is a perspective view schematically showing the laminate of FIG. 1.

[0020] FIG. 3 is a cross-sectional view taken along line I-I' of FIG. 1.

[0021] FIG. 4 is an exploded perspective view schematically showing an internal structure of the laminate of FIG. 1.

[0022] FIG. 5 is a partial cross-sectional view schematically showing a positive electrode layer of the all-solid-state battery of FIG. 1.

[0023] FIG. 6 is a partial cross-sectional view schematically showing a negative electrode layer of the all-solid-state battery of FIG. 1.

[0024] FIG. 7 is a partially enlarged cross-sectional view schematically showing the structure of a positive electrode layer, a negative electrode layer, and a solid electrolyte layer of the all-solid-state battery of FIG. 1.

[0025] FIG. 8 is a partially enlarged cross-sectional view schematically showing the structure of a positive electrode layer, a negative electrode layer, and a solid electrolyte layer of an all-solid-state battery according to another embodiment.

[0026] FIG. 9 is a graph representing the discharge capacity of all-solid-state batteries according to Examples 1 to 12 and Comparative Examples 1 to 6.

[0027] FIG. 10 is a graph representing the discharge capacity of all-solid-state batteries according to Examples 13 to 20 and Comparative Examples 7 to 16.

[0028] The present disclosure will be described in detail hereinafter with reference to the accompanying drawings, in which embodiments of the disclosure are illustrated. The drawings and descriptions are illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. Additionally, some components are exaggerated, omitted, or briefly illustrated in the drawings, and the sizes of the respective elements may not reflect actual dimensions. The accompanying drawings are provided only in order to allow embodiments disclosed in the present specification to be easily understood and are not to be interpreted as limiting the spirit disclosed in the present specification, and it is to be understood that the present disclosure includes all modifications, equivalents, and substitutions without departing from the scope and spirit of the present disclosure.

[0029] Terms including ordinal numbers such as first, second, and the like will be used only to describe various constituent elements, and are not to be interpreted as limiting these constituent elements. The terms are only used to differentiate one constituent element from other constituent elements.

[0030] It will be understood that when an element such as a layer, film, region, area, or substrate is referred to as being "on" or "above" 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, in the specification, the word "on" or "above" means disposed on or below the object portion, and does not necessarily mean disposed on the upper side of the object portion based on a gravitational direction.

[0031] Throughout the specification, it should be understood that the term "include", "comprise", "have", or "configure" indicates that a feature, a number, a step, an operation, a constituent element, a part, or a combination thereof described in the specification is present, but does not exclude a possibility of presence or addition of one or more other features, numbers, steps, operations, constituent elements, parts, or combinations, in advance. Unless explicitly stated otherwise, 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.

[0032] Furthermore, throughout the specification, the phrase "in a plan view" or "on a plane" means viewing a target portion from the top, and the phrase "in a cross-sectional view" or "on a cross-section" means viewing a cross-section formed by vertically cutting a target portion from the side.

[0033] Additionally,, throughout the specification, "connected" does not only mean when two or more elements are directly connected, but also when two or more elements are indirectly connected through other elements, and when they are physically connected or electrically connected, and further, it may be referred to by different names depending on a position or function, and may also be referred to as a case in which respective parts that are substantially integrated are linked to each other.

[0034] 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 the laminate of FIG. 1, FIG. 3 is a cross-sectional view taken along line I-I' of FIG. 1, and FIG. 4 is an exploded perspective view schematically showing an internal structure of the laminate of FIG. 1. In addition, FIG. 5 is a partial cross-sectional view schematically showing a 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.

[0035] Referring to FIG. 1 and FIG. 2, an all-solid-state battery 1000 may comprise a laminate 100, a first external electrode 300, and a second external electrode 400.

[0036] First, regardingdirections defined for describing the present embodiment, L-axis, W-axis, and T-axis shown in the drawings represent, a length direction, a width direction, and a thickness direction of the all-solid-state battery 1000, respectively.

[0037] The thickness direction (T-axis direction) may be a direction perpendicular to a wide surface (major surface) of sheet-like constituent elements. For example, the thickness direction (T-axis direction) may be used as the same concept as a direction in which components of the laminate 100 are stacked.

[0038] The length direction (L-axis direction) is a direction parallel to the wide surfaces (main surfaces) of the sheet-like components, and may be a direction that intersects (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 face each other.

[0039] The width direction (W-axis direction) is parallel to the wide surface (main surface) of the sheet-like components and may intersect (or cross) both the thickness direction (T-axis direction) and the length direction (L-axis direction). The laminate 100 may have a substantially hexahedral shape, however the present embodiment is not limited thereto. Due to shrinkage during sintering, the laminate 100 may not have a complete hexahedral shape, but may have a substantially hexahedral shape. For example, the laminate 100 has a substantially rectangular hexahedral shape, but corner or vertex portions may have a round shape.

[0040] In the present embodiment, for convenience of description, surfaces opposing each other in the length direction (L-axis direction) of the laminate 100 may be 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 may be 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 may be defined as a fifth surface S5 and a sixth surface S6.

[0041] Therefore, a first direction, which is a 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 that are 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), respectively, or the width direction (W-axis direction) and the thickness direction (T-axis direction), respectively.

[0042] A length of the laminate 100 may mean, 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 a center of the width direction (W-axis direction) of the laminate 100, a maximum value of lengths of a plurality of line segments that connect two outermost boundary lines facing each other in the length direction (L-axis direction) of the laminate 100 shown in the above cross-sectional photograph and are parallel to the length direction (L-axis direction). Meanwhile, the length of the laminate 100 may mean a minimum value of lengths of a plurality of line segments that connect two outermost boundary lines facing each other in the length direction (L-axis direction) of the laminate 100 shown in the above cross-sectional photograph and are parallel to the length direction (L-axis direction). On the other hand, the length of the laminate 100 may mean an arithmetic average value of lengths of at least two of a plurality of line segments that connect two outermost boundary lines facing each other in the length direction (L-axis direction) of the laminate 100 shown in the above cross-sectional photograph and are parallel to the length direction (L-axis direction).

[0043] A thickness of the laminate 100 may mean, based on an optical microscope or scanning electron microscope (microscope SEM) photograph of a cross-section in the length direction (L-axis direction)-the thickness direction (T-axis direction) at a center of the width direction (W-axis direction) of the laminate 100, a maximum value of lengths of a plurality of line segments that connect two outermost boundary lines facing each other in the thickness direction (T-axis direction) of the laminate 100 shown in the above cross-sectional photograph and are parallel to the thickness direction (T-axis direction). Alternatively, the thickness of the laminate 100 may mean a minimum value of lengths of a plurality of line segments that connect two outermost boundary lines facing each other in the thickness direction (T-axis direction) of the laminate 100 shown in the above cross-sectional photograph and are parallel to the thickness direction (T-axis direction). Alternatively, the thickness of the laminate 100 may mean an arithmetic average value of lengths of at least two of a plurality of line segments that connect two outermost boundary lines facing each other in the thickness direction (T-axis direction) of the laminate 100 shown in the above cross-sectional photograph and are parallel to the thickness direction (T-axis direction).

[0044] A width of the laminate 100 may mean, based on an optical microscope or scanning electron microscope (SEM) photograph of a cross-section in the length direction (L-axis direction)-the width direction (W-axis direction) at a center of the thickness direction (T-axis direction) of the laminate 100, a maximum value of lengths of a plurality of line segments that connect two outermost boundary lines facing each other in the width direction (W-axis direction) of the laminate 100 shown in the above cross-sectional photograph and are parallel to the width direction (W-axis direction). Alternatively, the width of the laminate 100 may mean a minimum value of lengths of a plurality of line segments that connect two outermost boundary lines facing each other in the width direction (W-axis direction) of the laminate 100 shown in the above 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 of a plurality of line segments that connect two outermost boundary lines facing each other in the width direction (W-axis direction) of the laminate 100 shown in the above cross-sectional photograph and are parallel to the width direction (W-axis direction).

[0045] Referring to FIG. 2 through FIG. 6, the laminate 100 may include solid electrolyte layers 110, positive electrode layers 130, negative electrode layers 150, an upper protective layer 160, a lower protective layer 170, and a margin portion 180. 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 laminated structure may repeat within 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.

[0046] The positive electrode layer 130 may be disposed on one surface of the solid electrolyte layer 110, while the negative electrode layer 150 may be disposed on the other surface of the solid electrolyte layer 110.

[0047] The solid electrolyte layer 110 includes a solid electrolyte, which may serve as a pathway for lithium (Li) ions. The solid electrolyte included in the solid electrolyte layer 110 may include a glass-ceramic electrolyte including lithium halide (LiX, where X is a halogen element such as F, Br, Cl, I, or the like). The glass-ceramic (or crystallization glass) refers to that a crystallographic mixture of amorphous and crystalline materials from which peaks and halos are observed in X-ray diffraction, electron beam diffraction, etc. Therefore, the glass-ceramic-based electrolyte is an electrolyte that has undergone partial crystallization through sintering and in which amorphous and crystalline materials are mixed.

[0048] 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.

[0049] When the glass-ceramic-based electrolyte is incorporated in the solid electrolyte layer 110, sufficient densification is achieved after sintering, whereby it is possible to realize high ionic conductivity.

[0050] As an example, the glass-ceramic 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 electrolyte may include a lithium chloroboracite-based electrolyte doped with aluminum, and as a specific example, the glass-ceramic electrolyte may include Li2O-B2O3-LiCl-Al2O3or Li4B4Al3O12Cl.

[0051] As another example, the solid electrolyte included 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.

[0052] When the LBSO-based electrolyte is included in the solid electrolyte layer 110, it is possible to keep the amorphous state during sintering while lowering the sintering temperature.　 Therefore, 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).

[0053] 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.

[0054] In an area where the margin portion 180, which will be described later, is disposed, a material having a low ionic conductivity and electrical conductivity, i.e. an insulating material, may be present, or a material having an ionic conductivity (or electrical conductivity) similar to the ionic conductivity (or electrical conductivity) of the solid electrolyte may be present. 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 portion, the material may be a material that is identical to or different from the solid electrolyte in other regions. In another example, a material with 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 portion.

[0055] 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.

[0056] 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.

[0057] Further, 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.

[0058] The positive electrode layer 130 may be exposed outside of the laminate 100 from the first surface S1 and connected to the first external electrode 300.

[0059] Referring to FIG. 3, FIG. 4, and FIG. 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.

[0060] For example, the positive electrode current collector 133 may be made of a plate-shape 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.

[0061] The positive electrode current collector 133 may include a first surface 133a and a second surface 133b. The first surface 133a and the second surface 133b oppose each other in the thickness direction (T-axis direction).

[0062] The positive electrode current collector 133 may comprise, but is not limited to, a porous metal plate made of stainless steel, nickel (Ni), copper (Cu), tin (Sn), aluminum (Al), or their alloys. 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.

[0063] 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.

[0064] Additionally, the positive electrode current collector may also include one or more types of solid electrolyte.

[0065] The first positive electrode active material layer 135 and the second positive electrode active material layer 136 may include positive electrode active materials and be disposed on a surface of the positive electrode current collector 133. 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 positive electrode current collector 133, but the method for forming the positive electrode active material layer is not limited thereto.

[0066] 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 electrode active material may contain lithium ions and serve to provide the lithium ions to the negative electrode when the all-solid-state battery is being charged. The positive electrode active material may affect the capacity and output of the all-solid-state battery.

[0067] 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 which formula, A may be Ni, Co, or Mn; M may be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Nb, Ti or a rare-earth element; D may be O, F, S, or P; E may be Co or Mn; X may be F, S, or P; G may be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, or V; Q may be Ti, Mo or Mn; R may be Cr, V, Fe, Sc, or Y; and J may be V, Cr, Mn, Co, Ni, or Cu.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] Additionally, the positive electrode layer 130 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 positive electrode layer. Therefore, it is possible to reduce interface resistance.

[0073] The negative electrode layer 150 may be exposed outside of the laminate 100 from the second surface S2, and connected to the second external electrode 400.

[0074] Referring to FIG. 3, FIG. 4, and FIG. 5, 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.

[0075] The negative electrode current collector 153 may be formed from, for example, a plate-shaped member or a thin member. As another example, the negative electrode current collector 153 may include a porous body having a reticulate shape, a mesh shape, or the like.

[0076] The negative electrode current collector 153 may have 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).

[0077] 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.

[0078] Additionally, the negative electrode current collector 153 may be coated with an oxidation-resistant metal or alloy film to prevent oxidation. The negative electrode current collector 153, like the positive electrode current collector 133, may include a conductive carbon-based material, and may include 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.

[0079] The first negative electrode active material layer 155 and the second negative electrode active material layer 156 may include negative electrode active materials and 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 for forming a negative electrode active material layer is not limited thereto.

[0080] 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.

[0081] The lithium metal alloy may contain lithium, and a metal / metalloid capable of forming an alloy with lithium. For example, the metal / metalloid capable of making 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.

[0082] 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.

[0083] In addition, 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.

[0084] 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 coke, graphene, carbon black, fullerene soot, carbon nanotube, carbon fiber, etc.

[0085] 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.

[0086] The negative electrode active material may optionally include a conductive material and a binder.

[0087] 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.

[0088] 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.

[0089] Additionally, 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. Therefore, it is possible to reduce interface resistance.

[0090] FIG. 7 is a partially enlarged cross-sectional view schematically showing a structure of the positive electrode layer, the negative electrode layer and the solid electrolyte layer of the all-solid-state battery of FIG. 1.

[0091] Referring to FIG. 7, one solid electrolyte layer 110 may simultaneously contact the positive electrode layer 130 and the negative electrode layer 150. One surface of the solid electrolyte layer 110 may contact the positive electrode active material layer 136 of the positive electrode layer 130, while the other surface may contact the negative electrode active material layer 155 of the negative electrode layer 150. Thus, the solid electrolyte layer 110 may be disposed between the positive electrode active material layer 136 and the negative electrode active material layer 155. The value ((t1+t2) / t3) (hereinafter referred to as the ‘thickness ratio’) obtained by dividing the sum (t1+t2) of a thickness t1 of the positive electrode active material layer 136 and a thickness t2 of the negative electrode active material layer 155 by a thickness t3 of the solid electrolyte layer 110 may be greater than 0.5 and less than 5.8, and the thickness t3 of the solid electrolyte layer 110 may exceed 5 μm.

[0092] If the thickness ratio is 0.5 or less or 5.8 or more, charge / discharge capacity of the all-solid-state battery may be insufficient.

[0093] If the thickness t3 of the solid electrolyte layer 110 is 5 μm or less, it may be too thin and cause a short circuit between the positive electrode layer 130 and the negative electrode layer 150. Furthermore, the probability of a short circuit may increase significantly due to increased leakage current.

[0094] In an embodiment, when the solid electrolyte included in the solid electrolyte layer 110 is an oxide-based solid electrolyte (e.g., lithium-lanthanum-zirconium-oxide (LLZO)) having an ionic conductivity of 10-4S / cm, the thickness ratio may be greater than 0.5 and less than 5.8, and the thickness t3 of the solid electrolyte layer 110 may be 6.2 μm or more and 19.8 μm or less.

[0095] In another embodiment, when the solid electrolyte included in the solid electrolyte layer 110 is an oxide-based solid electrolyte (e.g., lithium chloroboracite-based electrolyte doped with aluminum) having an ionic conductivity of 10-6S / cm, the thickness ratio may greater than 0.8 and less than or equal to 2.7, and the thickness t3 of the solid electrolyte layer 110 may be greater than or equal to 6.0 μm and less than or equal to 14.8 μm.

[0096] Here, a thickness of the positive electrode active material layer 136, a thickness of a negative electrode active material layer 153 and a thickness of the solid electrolyte layer 110 may mean an average thickness, respectively. The average thickness of the positive electrode active material layer 136, the average thickness of the negative electrode active material layer 153, and the average thickness of the solid electrolyte layer 110 may be measured by scanning the length direction (L-axis direction)-the thickness direction (T-axis direction) cross-section of the laminate with a scanning electron microscope (SEM) at 10,000 magnification. In the scanned image, the thicknesses may be measured at 30 equally spaced points along the length direction (L-axis direction) for one positive electrode active material layer, one solid electrolyte layer, and one negative electrode active material layer. The average value is then calculated. The 30 equally spaced points may be located in a region where the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer overlap in the thickness direction (T-axis direction).

[0097] The upper protective layer 160 and the lower protective layer 170 may be outermost layers disposed on the fifth surface S5 and the sixth surface S6 of the laminate 100, respectively. That is, the upper protective layer 160 may be the outermost layer toward the fifth surface S5 of the laminate 100, and the lower protective layer 170 may be the outermost layer toward the sixth surface S6 of the laminate 100. The upper protective layer 160 and the lower protective layer 170 may improve moisture resistance by preventing moisture penetration, and prevent damage from physical and chemical impacts.

[0098] The upper protective layer 160 and the lower protective layer 170 may comprise insulation layers made of insulating material, meaning a material that lacks electrical or ionic conductivity. 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 and / or nitrides of such materials, or any other suitable ceramic materials, but is not limited thereto. In addition, the upper protective layer 160 and the lower protective layer 170 may selectively include the above-described solid electrolytes, and may include one or more types of solid electrolytes, but are not limited thereto.

[0099] The margin portion 180 may be disposed along the edges of the positive electrode layer 130 and the negative electrode layer 150. The margin portion 180 may be disposed to be in contact with a remaining edge 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 portion 180 may be disposed to be in contact with a remaining edge of the negative electrode layer 150, except where the negative electrode layer 150 is connected to the second external electrode 400.

[0100] For example, the margin portion 180 may be disposed on the solid electrolyte layer 110 in a region other than the region where the positive electrode layer 130 or the negative electrode layer 150 is disposed. When the positive electrode layer 130 is disposed on the solid electrolyte layer 110, the margin portion 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 portion 180 may be disposed in a region other than the region where the negative electrode layer 150 is disposed.

[0101] Referring to FIG. 3, the margin portion 180 may comprise a portion of the first surface S1 and a part of the second surface S2 of the laminate 100. Meanwhile, although not illustrated, the margin portion 180 may also comprise a portion of the third surface S3 and a part of the fourth surface S4 of the laminate 100.

[0102] The margin portion 180 may be positioned 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 portion 180 may be disposed on the same surface as the positive electrode layer 130 and the negative electrode layer 150. The margin portion 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.

[0103] Additionally, the margin portion 180 may be made of a material that is resistant to moisture and has low lithium (Li) ion conductivity. In this case, the margin portion 180 may protect the active material layers 135, 136, 155, and 156 from moisture infiltration or lithium (Li) ion leakage. For example, the margin portion 180 may include an insulating material or electrolyte material, and may include a material with an ionic conductivity of 1.0x10-10S / cm or less.

[0104] The margin portion 180 may include an insulating material, i.e., a material that is not electrically (ionically) conductive.

[0105] The margin portion 180 may include, but not limited to, at least one selected from the group consisting of ceramic materials, e.g., 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 materials.

[0106] Additionally, the margin portion 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.

[0107] Additionally, a material having a low ionic conductivity and electrical conductivity, i.e., an insulating material, may be present in the margin portion 180, or a material with an ionic conductivity (or electrical conductivity) similar to the ionic conductivity (or electrical conductivity) of a solid electrolyte may be present in the margin portion 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 portion, 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 portion.

[0108] The first external electrode 300 and the second external electrode 400 are disposed outside the laminate 100.

[0109] 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.

[0110] In another embodiment, in another embodiment, the first external electrode 300 may extend onto one surface of the fifth surface S5 and the sixth surface S6 of the laminate 100, to partially cover the corresponding surface.

[0111] 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).

[0112] The second external electrode 400 may be 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.

[0113] In another embodiment, in another embodiment, the second external electrode 400 may extend onto one surface of the fifth surface S5 and the sixth surface S6 of the laminate 100, to partially cover the corresponding surface.

[0114] 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).

[0115] For example, the first surface S1 and the second surface S2 of the laminate 100 are dipped into the conductive paste and then 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, to form the first external electrode 300 and the second external electrode 400. As still another example, a dry film obtained by drying a 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 for forming the first external electrode 300 and the second external electrode 400 is not limited to the above-described method. For example, the conductive metal 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.

[0116] FIG. 8 is a partially enlarged cross-sectional view schematically showing the structure of the positive electrode layer, the negative electrode layer and the solid electrolyte layer of the all-solid-state battery according to another embodiment.

[0117] Referring to FIG. 8, one solid electrolyte layer 110 may be in contact with the positive electrode layer 130 and a negative electrode layer 150', simultaneously. One surface of the solid electrolyte layer 110 may be in contact with the positive electrode active material layer 136 of the positive electrode layer 130, and the other surface may be in contact with a negative electrode active material layer 155' of the negative electrode layer 150'. That is, the solid electrolyte layer 110 may be disposed between the positive electrode active material layer 136 and the negative electrode active material layer 155'. However, the negative electrode layer 150’ differs from the negative electrode layer 150 of the embodiment represented in FIG. 1 in that it does not include the negative electrode current collector but instead is composed of the negative electrode active material layer 155’.

[0118] The thickness ratio, that is, the value ((t1+t2') / t3) obtained by dividing a sum (t1+t2') of the thickness t1 of the positive electrode active material layer 136 and a thickness t2' of the negative electrode active material layer 155' by the thickness t3 of the solid electrolyte layer 110 may be greater than 0.5 and less than 5.8, and the thickness t3 of the solid electrolyte layer 110 may exceed 5 μm.

[0119] Here, half of the thickness t4 of the negative electrode layer 150' may be used as the thickness t2' of the negative electrode active material layer 155' for calculating the thickness ratio. The remaining components are the same as or correspond to the components of the all-solid-state battery shown in FIG. 1, so the repeated description thereof will be omitted.

[0120]

[0121] [Preparation Example 1: manufacture of all-solid-state battery]

[0122] A plurality of stripe-shaped positive electrode layers were formed by printing on a solid electrolyte layer (green sheet) containing a lithium-lanthanum-zirconium-oxide (LLZO) in the order of positive electrode active material layer, positive electrode current collector, and positive electrode active material layer, and then filling the space between the positive electrode layers with an insulating material to form a positive electrode sheet.

[0123] A plurality of stripe-shaped negative electrode layers were formed by printing on a solid electrolyte layer (green sheet) containing a lithium-lanthanum-zirconium-oxide (LLZO) in the order of negative electrode active material layer, cathode current collector, and negative electrode active material layer, and then filling the space between the negative electrode layers with an insulating material to form a negative electrode sheet..

[0124] A green chip was formed by stacking the positive electrode sheet and the negative electrode sheet so that the positive electrode sheet and the negative electrode sheet intersect each other.

[0125] A laminate was formed by dicing the green chip.

[0126] The laminate was calcined at 300°C to 400°C in an air or nitrogen atmosphere.

[0127] After the calcination, the laminate was sintered at 500°C to 700°C in an air or nitrogen atmosphere.

[0128] An all-solid-state battery was prepared by applying a conductive paste for external electrodes 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.

[0129] Here, all-solid-state batteries according to Examples 1 to 12 and Comparative Examples 1 to 6 were manufactured by changing the thickness of the positive electrode active material layer, the thickness of the negative electrode active material layer and the thickness of the solid electrolyte layer as shown in Table 1.

[0130] Thickness t1 of positive electrode active material layerThickness t3 of solid electrolyte layerThickness t2 of negative electrode active material layerThickness ratio((t1+t2) / t3)Comparative Example 16.4 um3.8 um6.0 um3.3Comparative Example 24.3 um4.2 um4.0 um2.0Comparative Example 34.4 um4.8 um4.0 um1.8Example 14.7 um6.2 um3.6 um1.3Example 24.7 um7.1 um3.8 um1.2Example 34.5 um9.7 um4.4 um0.9Example 44.6 um11.1 um3.8 um0.8Example 54.5 um14.6 um3.7 um0.6Comparative Example 44.6 um15.8 um3.8 um0.5Comparative Example 54.6 um19.8 um3.8 um0.4Example 63.0 um8.2 um2.4 um0.7Example 74.8 um8.4 um3.8 um1.0Example 87.2 um8.5 um5.4 um1.5Example 910.8 um8.7 um6.0 um1.9Example 1013.4 um8.3 um8.8 um2.7Example 1119.8 um8.5 um10.3 um3.5Example 1224.5 um8.6 um13.5 um4.4Comparative Example 628.0 um8.5 um21.5 um5.8

[0131] [Experimental Example 1: performance of all-solid-state battery]Five all-solid-state batteries of Examples 1 to 12 and Comparative Examples 1 to 6 were manufactured for each, and the discharge capacity per current rate (C-rate) was measured for one representative sample.

[0132] All-solid-state batteries exhibiting a discharge capacity of 1 / 2 or more of the maximum discharge capacity at 0.5C were deemed "suitable" for high-speed charge and discharge. Conversely, those with a discharge capacity of less than 1 / 2 of the maximum discharge capacity, or whose discharge capacity could not be measured, were deemed "unsuitable" for high-speed charge and discharge. The results are presented in Table 2 and FIG. 9.

[0133] Discharge capacity (mAh)Suitability for high-speed charge and dischargeC-rate0.05C0.1C0.2C0.5CComparative Example 1----UnsuitableComparative Example 2----UnsuitableComparative Example 3----UnsuitableExample 139.538.738.337.5SuitableExample 236.835.735.333.9SuitableExample 331.529.628.427.7SuitableExample 430.228.126.625.7SuitableExample 526.223.622.321.5SuitableComparative Example 423.520.719.318.3UnsuitableComparative Example 521.418.216.715.0UnsuitableExample 626.526.025.725.2SuitableExample 734.833.833.432.7SuitableExample 838.535.433.932.0SuitableExample 941.237.135.033.0SuitableExample 1038.031.930.428.1SuitableExample 1139.231.429.025.5SuitableExample 1240.030.026.420.8SuitableComparative Example 640.528.424.318.2Unsuitable

[0134] Referring to Table 2 and FIG. 9, the discharge capacities of the all-solid-state battery manufactured according to Examples 1 to 12 were found to be 20.8 mAh or more and 37.5 mAh or less. The all-solid-state batteries prepared according to Comparative Examples 1-3 suffered a short circuit and the discharge capacity could not be measured. This appears to be because the solid electrolyte layer is too thin. The discharge capacities of the all-solid-state battery manufactured according to Comparative Examples 4 to 6 were found to be 18.3 mAh, 15.0 mAh, and 18.2 mAh, respectively. Since this is less than 18.75 mAh, which is 1 / 2 of the maximum value of 37.5 mAh, the all-solid-state batteries manufactured according to Comparative Examples 4 to 6 were deemed unsuitable for high-speed charge and discharge. This appears to be because the solid electrolyte layer is too thin or too thick compared to the thicknesses of the positive electrode active material layer and the negative electrode active material layer.

[0135] [Preparation Example 2: manufacture of all-solid-state battery]

[0136] A plurality of stripe-shaped positive electrode layers were formed by printing on a solid electrolyte layer (green sheet) containing a lithium chloroboracite-based electrolyte doped with aluminum in the order of positive electrode active material layer, positive electrode current collector, and positive electrode active material layer, and then filling the space between the positive electrode layers with an insulating material to form a positive electrode sheet.

[0137] A plurality of stripe-shaped negative electrode layers were formed by printing on a solid electrolyte layer (green sheet) containing a lithium chloroboracite-based electrolyte doped with aluminum in the order of negative electrode active material layer, negative electrode current collector, and negative electrode active material layer, and then filling the space between the negative electrode layers with an insulating material to form a negative electrode sheet.

[0138] A green chip was formed by stacking the positive electrode sheet and the negative electrode sheet such that they intersect each other. A laminate was formed by dicing the green chip.

[0139] The laminate was calcined at 300°C to 400°C in an air or nitrogen atmosphere.

[0140] After the calcination, the laminate was sintered at 400°C to 550°C in an air or nitrogen atmosphere.

[0141] An all-solid-state battery was prepared by applying a conductive paste for external electrodes 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.

[0142] Here, all-solid-state batteries according to Examples 13 to 20 and Comparative Examples 7 to 16 were manufactured by changing the thickness of the positive electrode active material layer, the thickness of the negative electrode active material layer and the thickness of the solid electrolyte layer as shown in Table 3.

[0143] Thickness t4 of positive electrode active material layerThickness t6 of solid electrolyte layerThickness t5 of negative electrode active material layerThickness ratio((t4+t5) / t6)Comparative Example 76.5 um4.1 um6.0 um3.0Comparative Example 84.4 um4.6 um4.0 um1.8Comparative Example 94.5 um5.0 um4.0 um1.7Example 134.7 um6.0 um3.5 um1.4Example 144.8 um7.0 um3.8 um1.2Example 154.6 um9.8 um4.5 um0.9Comparative Example 104.7 um11.2 um3.7 um0.8Comparative Example 114.6 um14.8 um3.7 um0.6Comparative Example 124.6 um16.0 um3.7 um0.5Comparative Example 134.6 um20.0 um3.7 um0.4Example 163.2 um8.3 um2.5 um0.7Example 174.7 um8.5 um3.8 um1.0Example 187.2 um8.3 um5.1 um1.5Example 1910.8 um8.6 um5.8 um1.9Example 2013.5 um8.2 um8.7 um2.7Comparative Example 1420.2 um8.4 um10.2 um3.6Comparative Example 1525.0 um8.4 um14.0 um4.6Comparative Example 1630.0 um8.4 um22.0 um6.2

[0144] [Experimental Example 2: performance of all-solid-state battery]Five all-solid-state batteries of Examples 13 to 20 and Comparative Examples 7 to 16 were manufactured for each, and the discharge capacity per current rate (C-rate) was measured for one representative sample.

[0145] All-solid-state batteries exhibiting a discharge capacity of 1 / 2 or more of the maximum discharge capacity at 0.5C were deemed "suitable" for high-speed charge and discharge. Conversely, those with a discharge capacity of less than 1 / 2 of the maximum discharge capacity, or whose discharge capacity could not be measured, were deemed "unsuitable" for high-speed charge and discharge. The results are presented in Table 4 and FIG. 10.

[0146] Discharge capacity (mAh)Suitability for high-speed charge and dischargeC-rate0.05C0.1C0.2C0.5CComparative Example 7----UnsuitableComparative Example 8----UnsuitableComparative Example 9----UnsuitableExample 1338.237.436.334.4SuitableExample 1435.534.433.431.6SuitableExample 1529.626.624.323.1SuitableComparative Example 1028.424.722.217.0UnsuitableComparative Example 1124.519.617.212.3UnsuitableComparative Example 1223.518.815.310.6UnsuitableComparative Example 1320.016.012.08.0UnsuitableExample 1628.026.325.224.6SuitableExample 1734.032.029.928.9SuitableExample 1838.535.433.528.9SuitableExample 1937.833.630.225.7SuitableExample 2035.029.827.317.5SuitableComparative Example 1434.227.423.915.4UnsuitableComparative Example 1538.028.522.815.2UnsuitableComparative Example 1639.028.119.511.7Unsuitable

[0147] Referring to Table 4 and FIG. 10, the discharge capacities of the all-solid-state battery manufactured according to Examples 13 to 20 were found to be 17.5 mAh or more and 34.4 mAh or less. The all-solid-state batteries manufactured according to Comparative Examples 7 to 9 suffered a short circuit and the discharge capacity could not be measured. This appears to be because the solid electrolyte layer is too thin. The discharge capacities of the all-solid-state battery manufactured according to Comparative Example 10-16 were found to be 8.0 mAh or more and 17.0 mAh or less. Since this is less than 17.2 mAh, which is 1 / 2 of the maximum value of 34.4 mAh, the all-solid-state batteries manufactured according to Comparative Example 10-16 were determined to be unsuitable for high-speed charge and discharge. This appears to be because the solid electrolyte layer is too thin or too thick compared to the thicknesses of the positive electrode active material layer and the negative electrode active material layer. While this disclosure has been described in connection with what are presently considered practical embodiments, it should be understood that the disclosure is not limited to these embodiments. On the contrary, it is intended to encompass various modifications and equivalent arrangements within the spirit and scope of the appended claims.

[0148] <Description of symbols>

[0149] 1000: all-solid-state battery

[0150] 100: laminate

[0151] 110: solid electrolyte layer

[0152] 130: positive electrode layer

[0153] 150: negative electrode layer

[0154] 160: upper protective layer

[0155] 170: lower protective layer

[0156] 180: margin portion

[0157] 300: first external electrode

[0158] 400: second external electrode

Claims

1.An all-solid-state battery, comprising a laminate comprising a solid electrolyte layer, a positive electrode active material layer in contact with one surface of the solid electrolyte layer, and a negative electrode active material layer in contact with another surface of the solid electrolyte layer,wherein a value obtained by dividing a sum of a thickness of the positive electrode active material layer and a thickness of the negative electrode active material layer by a thickness of the solid electrolyte layer is greater than 0.5 and less than 5.8, and the thickness of the solid electrolyte layer exceeds 5 μm.2.The all-solid-state battery of claim 1, wherein the solid electrolyte layer comprises a solid electrolyte having an ionic conductivity of 10-4S / cm.3.The all-solid-state battery of claim 2, wherein the solid electrolyte comprises lithium-lanthanum-zirconium-oxide (LLZO).4.The all-solid-state battery of claim 2, wherein the thickness of the solid electrolyte layer is 6.2 μm or more and 19.8 μm or less.5.The all-solid-state battery of claim 2, wherein the thickness of the positive electrode active material layer is 3.0 μm or more and 24.5 μm or less.6.The all-solid-state battery of claim 2, wherein the thickness of the negative electrode active material layer is 2.4 μm or more and 13.5 μm or less.7.The all-solid-state battery of claim 1, wherein the value obtained by dividing the sum of the thickness of the positive electrode active material layer and the thickness of the negative electrode active material layer by the thickness of the solid electrolyte layer is greater than 0.8 and less than or equal to 2.7.8.The all-solid-state battery of claim 7, wherein the solid electrolyte layer comprises a solid electrolyte having an ionic conductivity of 10-6S / cm.9.The all-solid-state battery of claim 8, wherein the solid electrolyte comprises a lithium chloroboracite-based electrolyte doped with aluminum.10.The all-solid-state battery of claim 8, wherein the thickness of the solid electrolyte layer is 6.0 μm or more and 14.8 μm less.11.The all-solid-state battery of claim 8, wherein the thickness of the positive electrode active material layer is 3.2 μm or more and 13.5 μm or less.12.The all-solid-state battery of claim 8, wherein the thickness of the negative electrode active material layer is 2.5 μm or more and 8.7 μm or less.

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