All-solid-state battery and method for manufacturing same

Abstract

The present invention relates to an all-solid-state battery. More specifically, the all-solid-state battery comprises a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, the solid electrolyte layer including: a first solid electrolyte layer adjacent to the positive electrode layer and having a first width and a first thickness; a second solid electrolyte layer adjacent to the negative electrode layer and having a second width and a second thickness; and an interlayer interposed between the first solid electrolyte layer and the second solid electrolyte layer and having a third width and a third thickness.

Description

All-solid-state battery and method for manufacturing the same

[0001] The present invention relates to an all-solid-state battery and a method for manufacturing the same.

[0002] Recent industrial demands have led to the active development of batteries with high energy density and safety. For example, lithium-ion batteries are being used not only in information and communication devices, but also in the automotive sector. Safety is particularly important in the automotive sector, as it is directly related to life.

[0003] Recently, all-solid-state batteries have been proposed, replacing the electrolyte in lithium-ion batteries with a solid electrolyte. By eliminating the use of flammable organic dispersion media, all-solid-state batteries significantly reduce the risk of fire or explosion in the event of a short circuit. Therefore, these all-solid-state batteries can offer superior safety.

[0004] The problem to be solved by the present invention is to provide an all-solid-state battery with improved stability and cell characteristics and a method for manufacturing the same.

[0005] According to the concept of the present invention, an all-solid-state battery may include a positive electrode layer; a negative electrode layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer.

[0006] It may include a first solid electrolyte layer adjacent to the positive electrode layer and having a first width and a first thickness, a second solid electrolyte layer adjacent to the negative electrode layer and having a second width and a second thickness, and an interlayer disposed between the first solid electrolyte layer and the second solid electrolyte layer and having a third width and a third thickness.

[0007] According to another concept of the present invention, an all-solid-state battery may include a first monocell; and a second monocell on the first monocell.

[0008] The second monocell can be arranged symmetrically vertically with respect to the first monocell.

[0009] Each of the first and second monocells may include a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer.

[0010] The positive electrode layer of the first monocell and the positive electrode layer of the second monocell may face each other.

[0011] The solid electrolyte layer of each of the first and second monocells may include a first solid electrolyte layer adjacent to the positive electrode layer and having a first width and a first thickness, a second solid electrolyte layer adjacent to the negative electrode layer and having a second width and a second thickness, and an interlayer disposed between the first solid electrolyte layer and the second solid electrolyte layer and having a third width and a third thickness.

[0012] According to another concept of the present invention, a method for manufacturing an all-solid-state battery includes a cathode layer, a second solid electrolyte layer disposed on the cathode layer and having substantially the same area as the cathode layer, a first solid electrolyte layer disposed on the second solid electrolyte layer and having a smaller width than the second solid electrolyte layer, an interlayer disposed between the first solid electrolyte layer and the second solid electrolyte layer and having substantially the same area as the first solid electrolyte layer, and a cathode layer disposed on the first solid electrolyte layer and having substantially the same area as the first solid electrolyte layer.

[0013] It may include forming a positive electrode laminate by laminating the positive electrode layer and the first solid electrolyte layer and then applying a first pressure; forming a negative electrode laminate by laminating the negative electrode layer and the second solid electrolyte layer and then applying a second pressure; laminating the positive electrode laminate and the interlayer; and combining the interlayer and the negative electrode laminate so that the first solid electrolyte layer and the second solid electrolyte layer are in contact with each other.

[0014] The first pressure may be greater than the second pressure.

[0015] The present invention may include a double-layer structure in which the solid electrolyte layer includes a first solid electrolyte layer and a second solid electrolyte layer. The solid electrolyte layer may include an interlayer positioned between the first solid electrolyte layer and the second solid electrolyte layer. This may reduce the interfacial resistance between the first solid electrolyte layer and the second solid electrolyte layer.

[0016] The present invention can prevent the formation of lithium dendrites from the negative electrode layer and suppress side reactions in the negative electrode layer. Consequently, the all-solid-state battery of the present invention can prevent short-circuiting and have improved cycle characteristics.

[0017] Figure 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0018] Figure 2 is a plan view of an all-solid-state battery according to one embodiment of the present invention.

[0019] Figure 3 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0020] Figure 4 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0021] Figure 5 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0022] Figure 6 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0023] Figure 7 is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention.

[0024] Figure 8 is a conceptual diagram illustrating a method for manufacturing an all-solid-state battery according to one embodiment of the present invention.

[0025] Figure 9 is a conceptual diagram illustrating a method for manufacturing an all-solid-state battery according to another embodiment of the present invention.

[0026] Figure 10 is a graph showing the internal potential of a solid electrolyte layer of an all-solid-state battery according to one embodiment of the present invention.

[0027] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and subject to various modifications. However, the description of these embodiments is provided solely to ensure a complete disclosure of the present invention and to fully inform those skilled in the art of the invention of the scope of the invention.

[0028] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, the thicknesses of the components are exaggerated for the sake of clarity. Parts designated by the same reference numerals throughout the specification represent the same components.

[0029] Embodiments described herein will be described with reference to cross-sectional and / or plan views, which are ideal illustrations of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for the purpose of effectively explaining the technical contents. Accordingly, the regions illustrated in the drawings have a schematic nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific shapes of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, and third are used to describe various components in various embodiments of the present specification, these components should not be limited by such terms. These terms are used only to distinguish one component from another. The embodiments described and illustrated herein also include complementary embodiments thereof.

[0030] The terminology used herein is for the purpose of describing embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise. As used herein, the words "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components.

[0031]

[0032] Fig. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention. Fig. 2 is a plan view of an all-solid-state battery according to one embodiment of the present invention.

[0033] Referring to FIG. 1, an all-solid-state battery (10) according to one embodiment may include a positive electrode layer (100), a negative electrode layer (200) facing the positive electrode layer (100), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). However, the present invention is not limited thereto, and the all-solid-state battery (10) may further include an additional functional layer, such as an adhesion enhancing layer, disposed between the positive electrode layer (100) and the solid electrolyte layer (300) or between the negative electrode layer (200) and the solid electrolyte layer (300).

[0034] The positive electrode layer (100) of one embodiment may include a positive electrode current collector (110) and a positive electrode active material layer (120) disposed on the positive electrode current collector (110). Although not shown, the positive electrode active material layer (120) may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0035] The positive electrode current collector (110) can provide a reference surface on which the positive electrode active material layer (120) is arranged. The positive electrode current collector (110) can include a plate or foil including, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0036] Meanwhile, unlike that illustrated in FIG. 1, in one embodiment of the present invention, the positive electrode current collector (110) may be omitted. Although not illustrated, a carbon layer having a thickness of 0.1 μm to 4 μm may be additionally disposed between the positive electrode current collector (110) and the positive electrode active material layer (120) to increase the bonding strength between the positive electrode current collector (110) and the positive electrode active material layer (120).

[0037] The cathode active material may include a material that can reversibly absorb and desorb lithium ions. The cathode active material may include a plurality of particles. The cathode active material may include, but is not necessarily limited to, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide. The cathode active materials may be used alone or as a mixture of two or more.

[0038] Lithium transition metal oxides include, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Mr b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Ni 1-b-c Mr b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni b HAVE BEEN c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Ni b Co c Mr d GeO2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1), Li a NiG b O2(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnG bO2(0.90≤a≤1, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1, 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3(0≤f≤2), Li 3-f A compound represented by any one of Fe2(PO4)3(0≤f≤2), LiFePO4. In these compounds, the capital letter “A” is Ni, Co, Mn, or a combination thereof, the capital letter “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, the capital letter “D” is O, F, S, P, or a combination thereof, the capital letter “E” is Co, Mn, or a combination thereof, the capital letter “F” is F, S, P, or a combination thereof, the capital letter “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, the capital letter “Q” is Ti, Mo, Mn, or a combination thereof, the capital letter “I” is Cr, V, Fe, Sc, Y, or a combination thereof, and the capital letter “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0039] The cathode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen atomic layers and metal atomic layers are alternately and regularly arranged in a direction, and thereby each atomic layer forms a two-dimensional plane. The "cubic rock salt structure" refers to the sodium chloride type (NaCl type) structure, which is a type of crystal structure, and specifically refers to a structure in which the face-centered cubic lattice (fcc) formed by each cation and anion is arranged with a displacement of half of the ridge of the unit lattice. Lithium transition metal oxides having this layered rock salt structure include, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn z O2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극 활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0040] The above-described compound included in the positive electrode active material may be covered by a coating layer (not shown). The positive electrode active material may also be a mixture of the above-described compound and a compound to which a coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material may include, for example, an oxide, a hydroxide, an oxyhydroxide, an oxycarbonate, or a hydroxycarbonate of the coating elements below. The compound forming the coating layer is amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The method for forming the coating layer includes, for example, spray coating, dipping, etc.

[0041] When the positive electrode active material includes nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, the capacity density of the all-solid-state battery (10) can be increased, thereby reducing metal dissolution of the positive electrode active material in a charged state. As a result, the cycle characteristics of the all-solid-state battery (10) in a charged state are improved. Meanwhile, the "cycle characteristics" are characteristics indicating the degree to which the all-solid-state battery (10) is deteriorated by charge / discharge of the all-solid-state battery (10). An all-solid-state battery (10) with high cycle characteristics may have a small degree of deterioration of the all-solid-state battery (10) due to charge / discharge, and an all-solid-state battery (10) with low cycle characteristics may have a large degree of deterioration of the all-solid-state battery (10) due to charge / discharge.

[0042] The positive electrode active material may have a particle shape such as a sphere or an ellipsoid, for example. The particle size and content of the positive electrode active material are not particularly limited.

[0043] A solid electrolyte may be dispersed between the positive electrode active materials. The solid electrolyte dispersed between the positive electrode active materials may have a particle shape. The solid electrolyte dispersed between the positive electrode active materials may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. Examples of the sulfide-based solid electrolyte include Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, capital letter “Z” represents Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, capital letter “M” is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may include at least one selected from (0≤x≤2).

[0044] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x(0≤x≤2) may be an argyrodite-type compound including at least one selected from. In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I. The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0045] The solid electrolyte in the positive active material layer (120) may have a smaller median particle size (D50) than the solid electrolyte in the solid electrolyte layer (300) described later. For example, the median particle size (D50) of the solid electrolyte included in the positive active material layer (120) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the median particle size (D50) of the solid electrolyte included in the solid electrolyte layer (300). Meanwhile, the median particle size (D50) may be a median diameter measured using a laser particle size distribution meter.

[0046] The positive electrode active material layer (120) may include a conductive material. The conductive material may have conductivity without causing a chemical change in the all-solid-state battery (10), thereby increasing the conductivity of the positive electrode active material and the solid electrolyte. The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0047] The positive electrode active material layer (120) may further include a binder. The binder may bind the positive electrode active material, the solid electrolyte, and the conductive material within the positive electrode active material layer (120) to each other. The binder may include a material for improving the bonding strength between the positive electrode active material layer (120) and the positive electrode current collector (110). The binder may include, for example, polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0048] Based on 100 parts by weight of the total of the positive electrode active material, the solid electrolyte, the conductive material, and the binder, the positive electrode active material layer (120) may include 85 parts by weight or more and 92 parts by weight or less of the positive electrode active material. Based on 100 parts by weight of the total of the positive electrode active material, the solid electrolyte, the conductive material, and the binder, the positive electrode active material layer (120) may include 0.5 parts by weight or more and 1.5 parts by weight or less of the binder.

[0049] Based on 100 parts by weight of the solid electrolyte in the positive electrode active material layer (120), the positive electrode active material layer (120) may include 1 part by weight or more and 50 parts by weight or less of a conductive material. When the conductive material is included in the positive electrode active material layer (120) in an amount of less than 1 part by weight based on 100 parts by weight of the solid electrolyte in the positive electrode active material layer (120), the proportion of the conductive material may decrease, thereby lowering the electrical conductivity of the positive electrode active material layer (120). When the conductive material is included in the positive electrode active material layer (120) in an amount of more than 50 parts by weight based on 100 parts by weight of the solid electrolyte in the positive electrode active material layer (120), the proportion of the conductive material may be excessively high, so that a coating layer covering the surface of the solid electrolyte may not be properly formed.

[0050] The positive electrode active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductive aids in addition to the above-described positive electrode active material, solid electrolyte, conductive agent, and binder.

[0051] The negative electrode layer (200) may include a negative electrode current collector (210) and a negative electrode coating layer (220) on the negative electrode current collector (210). The negative electrode current collector (210) may provide a reference surface on which the negative electrode coating layer (220) is disposed. The negative electrode current collector (210) may include, for example, a material that does not react with lithium, i.e., does not form an alloy or a compound with lithium. For example, the negative electrode current collector (210) may include at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector (210) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0052] The negative electrode current collector (210) may be composed of one of the above-described metals, or may include an alloy or coating material of two or more metals. The negative electrode current collector (210) may have, for example, a plate shape or a foil shape. Meanwhile, in one embodiment, the negative electrode current collector (210) may be omitted.

[0053] The negative electrode coating layer (220) can allow lithium metal to grow between it and the negative electrode current collector (210) when the all-solid-state battery (10) is charged. The negative electrode coating layer (220) can act as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0054] The cathode coating layer (220) may include a metal and carbon. For example, the cathode coating layer (220) may include at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The cathode coating layer (220) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the cathode coating layer (220) may include a mixture of carbon black and silver (Ag).

[0055] The cathode coating layer (220) may further include additives other than metal and carbon. The cathode coating layer (220) may further include, for example, at least one additive selected from the group consisting of a binder, a filler, a coating agent, a dispersant, and an ion conductive additive.

[0056] The negative electrode coating layer (220) may have a smaller thickness than the positive electrode active material layer (120). The thickness of the negative electrode coating layer (220) may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer (120). The thickness of the negative electrode coating layer (220) may be, for example, 1 um to 20 um, 2 um to 10 um, or 3 um to 7 um. If the thickness of the negative electrode coating layer (220) is too thin, lithium dendrites formed between the negative electrode coating layer (220) and the negative electrode current collector (210) may cause the negative electrode coating layer (220) to collapse, thereby deteriorating the cycle characteristics of the all-solid-state battery (10). If the thickness of the cathode coating layer (220) increases excessively, the energy density of the all-solid-state battery (10) may decrease and the internal resistance of the all-solid-state battery (10) due to the cathode coating layer (220) may increase, thereby deteriorating the cycle characteristics of the all-solid-state battery (10).

[0057] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the cathode coating layer (220) and the solid electrolyte layer (300).

[0058] A solid electrolyte layer (300) may be provided between the positive electrode layer (100) and the negative electrode layer (200). The solid electrolyte layer (300) may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer (300) may be the same as or different from any one of the materials included in the solid electrolyte in the positive electrode active material layer (120) described above.

[0059] The solid electrolyte layer (300) may include a first solid electrolyte layer (310), a second solid electrolyte layer (320), and an interlayer (330). The first solid electrolyte layer (310) may be adjacent to the positive electrode layer (100), and the second solid electrolyte layer (320) may be adjacent to the negative electrode layer (200). The interlayer (330) may be disposed between the first solid electrolyte layer (310) and the second solid electrolyte layer (320).

[0060] The second solid electrolyte layer (320) can be in direct contact with the negative electrode coating layer (220). As a result, the second solid electrolyte layer (320) can suppress lithium dendrites formed between the negative electrode coating layer (220) and the negative electrode current collector (210). The second solid electrolyte layer (320) can effectively suppress negative electrode side reactions. As a result, the cell performance of the all-solid-state battery (10) according to the present invention can be improved.

[0061] The interlayer (330) can lower the interfacial resistance between the first solid electrolyte layer (310) and the second solid electrolyte layer (320). The interlayer (330) can be an organic layer positioned between different inorganic solid electrolyte layers to lower the interfacial resistance.

[0062] The above interlayer (330) may include a heterogeneous polymer and a lithium salt.

[0063] The above heteropolymer may include an ionic polymer binder and a vinylidene fluoride-based binder. The ionic polymer binder may have an ionic property for lithium dissociation. The ionic polymer binder may be a polyethylene oxide-based binder or a polyacrylate-based binder. In one embodiment, the ionic polymer binder may be a polyethylene oxide-based binder, and the polyethylene oxide-based binder may be polyethylene oxide, but is not limited thereto.

[0064] The above vinylidene fluoride-based binder may be a polymer binder for forming a structure in the interlayer (330). In one embodiment, the vinylidene fluoride-based binder may be polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), but is not limited thereto.

[0065] In one embodiment, the lithium salt may be, but is not limited to, LiTFSI.

[0066] The above interlayer (330) may have a molar ratio of ethylene oxide (EO) and lithium (Li) of 1:1 to 100:1. The EO / Li molar ratio is related to the ionic conductivity of the interlayer (330), and the higher the ratio, the higher the ionic conductivity. In one embodiment, the EO / Li molar ratio may be 5 to 25.

[0067] The solid electrolyte in the solid electrolyte layer (300) may have a particle shape such as a sphere or ellipsoid.

[0068] The solid electrolyte in the solid electrolyte layer (300) may include a sulfide-based solid electrolyte. The solid electrolyte in the solid electrolyte layer (300) may be amorphous, crystalline, or a mixture thereof. In addition, the solid electrolyte may include, for example, at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements among the above-described sulfide-based solid electrolyte materials. For example, the solid electrolyte may be a material including Li2S-P2S5. When using a sulfide-based solid electrolyte material including Li2S-P2S5 to form the solid electrolyte, the mixing molar ratio of Li2S and P2S5 is, for example, in the range of Li2S:P2S5=50:50 to 90:10.

[0069] In one embodiment, the solid electrolyte in the solid electrolyte layer (300) is Li 7-a Ma PS 6-c X c It may be an argyrodite-type compound containing, where X may be Cl, Br, or a combination thereof. M may be Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof. Each of a and c may be a real number between 0 and 2.

[0070] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte in the solid electrolyte layer (300) is, for example, 15 GPa to 35 GPa.

[0071] The solid electrolyte layer (300) may further include a binder. The binder included in the solid electrolyte layer (300) may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto. The binder of the solid electrolyte layer (300) may be the same as or different from the binder included in the positive electrode active material layer (120) or the binder included in the negative electrode coating layer (220).

[0072]

[0073] Referring back to FIG. 1, the first solid electrolyte layer (310) may have a first thickness (t1), the second solid electrolyte layer (320) may have a second thickness (t2), and the interlayer (330) may have a third thickness (t3).

[0074] An embodiment of the present invention divides a solid electrolyte layer (300) into a first solid electrolyte layer (310) and a second solid electrolyte layer (320) and controls the thickness of each layer differently, thereby increasing energy density while suppressing the formation of lithium dendrites in the negative electrode, thereby improving stability against short-circuit risk and impact and providing an all-solid-state battery (10) with high energy density.

[0075] The above first thickness (t1) And the second thickness (t2) may have different thicknesses. The second thickness (t2) may be greater than the first thickness (t1).

[0076] The above first thickness t1 and the above second thickness t2 can satisfy the following equation 1.

[0077] [Formula 1]

[0078] 1 ≤ t2 / t1< 4.

[0079] The ratio (t2 / t1) of the second thickness t2 to the first thickness t1 may be 1 to 4. When the ratio (t2 / t1) of the second thickness t2 to the first thickness t1 is within the above-mentioned numerical range, the energy density can be increased while suppressing the formation of lithium dendrites in the negative electrode, thereby improving the stability against short-circuit risk and impact and providing an all-solid-state battery (10) with high energy density.

[0080] The above first thickness (t1) is preferably smaller, and can have a size range larger than that of the small particles in the anode layer (100) and up to the size of the opposing particles.

[0081] The first thickness (t1) may be 30 μm or less. Specifically, the first thickness (t1) may be 25 μm or less, 20 μm or less, 14 μm or less, or 10 μm or less. The first thickness (t1) may be 0.1 μm or more. Specifically, the first thickness (t1) may be 1 μm or more, 2 μm or more, 4 μm or more, or 5 μm or more.

[0082] If the first thickness (t1) exceeds the above-mentioned numerical range, the energy density of the all-solid-state battery (10) may decrease. If the first thickness (t1) falls short of the above-mentioned numerical range, the first thickness (t1) may not reach the diameter of the active material powder in the positive electrode, making it difficult to form an interface.

[0083] The second thickness (t2) may be 10 μm or more. Specifically, the second thickness (t2) may be 20 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 55 μm or more, or 60 μm or more. The second thickness (t2) may be 120 μm or less. Specifically, the second thickness (t2) may be 90 μm or less, or 60 μm or less. When the second thickness (t2) is less than the above-mentioned numerical range, it may be difficult to suppress the formation of lithium dendrites in the negative electrode, which may cause a short circuit. When the second thickness (t2) exceeds the above-mentioned numerical range, the energy density of the all-solid-state battery (10) may decrease.

[0084] In one embodiment, the sum of the first thickness (t1) and the second thickness (t2) may be 40 μm to 60 μm.

[0085] The third thickness (t3) may be 20 μm or less. Specifically, the first thickness (t1) may be 15 μm or less. The third thickness (t3) may be 0.1 μm or more. Specifically, the first thickness (t1) may be 1 μm or more, and may be 5 μm or more.

[0086] In one embodiment, the third thickness (t3) may be 1 μm to 10 μm.

[0087] If the above first thickness (t3) falls below the above-mentioned numerical range, interface formation may be difficult or interface resistance may increase.

[0088] The solid electrolyte layer (300) may have a fourth thickness (T).

[0089] The fourth thickness (T) may mean the sum of the first thickness (t1), the second thickness (t2), and the third thickness (t3). The fourth thickness (T) may mean a value directly related to energy density. As the fourth thickness (T) decreases, the energy density increases, but safety due to short circuit and crack may decrease. The thinner the fourth thickness (T), the higher the energy density, but if it is too thin, it may be difficult to suppress the formation of lithium dendrites in the negative electrode, which may cause a short circuit, and there may be a possibility that the all-solid-state battery (10) may be damaged by external impact.

[0090] The fourth thickness (T) may be 150 μm or less. Specifically, the fourth thickness (T) may be 120 μm or less, 90 μm or less, or 60 μm or less. The fourth thickness (T) may be 10 μm or more. Specifically, the fourth thickness (T) may be 30 μm or more, or 50 μm or more. When the fourth thickness (T) exceeds the above numerical range, the energy density of the all-solid-state battery (10) may decrease. In one embodiment, the fourth thickness (T) may be 45 μm to 60 μm.

[0091]

[0092] The above interlayer (330) can allow Li to move within the polymer binder. At a charging voltage of 4.25 V of the interlayer (330), the surface of the negative electrode layer (200) is 0 V vs. Li / Li+, and the surface of the positive electrode layer (100) is 4.24 V vs. Li / Li+, so that the potential can linearly increase from the negative electrode layer (200) to the positive electrode layer (100).

[0093] Fig. 10 is a graph showing the potential inside a solid electrolyte layer (300) having a thickness of 45 mm. Referring to Fig. 10, the vertical bold bar in the graph represents the potential window of the interlayer (330). The interlayer (330) may be electrochemically stable in the potential window of 0.5 to 4.0 V vs. Li / Li+. Accordingly, it can be confirmed that the interlayer (330) has a stable region within the solid electrolyte layer (300). In the graph, the stable region represents the d1 to d2 region when projected onto the solid electrolyte layer (300). In other words, when the interlayer (330) is introduced within the range of d1 to d2, it is electrochemically stable.

[0094] In the present invention, the position of the interlayer (330) in the solid electrolyte layer (300) may correspond to the region d1 to d2. For example, if the thickness (T) of the solid electrolyte layer (300) is 45 mm, the position of the interlayer (330) may be in the region 11.3% to 94.5%.

[0095] The position of the above interlayer (330) may be defined numerically as follows. The height of the interlayer within the solid electrolyte layer (300) may satisfy the following equation 2.

[0096] [Formula 2]

[0097] 50 (%) ≤ (d1 / T)*100 to [(d1+d3 / )T]*100 (%) ≤80 (%)

[0098] Here, d1 refers to the height of the first solid electrolyte layer (310) in the cross-sectional view of the all-solid-state battery, and d3 refers to the height of the interlayer (330) in the cross-sectional view of the all-solid-state battery.

[0099] If the position of the interlayer exceeds the mentioned numerical range, it may be biased toward the cathode, which may easily cause a short circuit. Therefore, it is preferable to place it toward the anode as much as possible. That is, the position of the interlayer (330) may be located between 50 (%) and 94.5 (%) of the thickness (T) of the solid electrolyte. In one embodiment, the position of the interlayer (330) may be located at 80 (%) of the thickness (T) of the solid electrolyte layer (300).

[0100]

[0101] Referring to FIGS. 1 and 2, the area of ​​the anode layer (100) and the area of ​​the cathode layer (200) may be different from each other. Specifically, the area of ​​the cathode layer (200) may be larger than the area of ​​the anode layer (100). The anode layer (100) may be completely overlapped within the cathode layer (200).

[0102] In one embodiment of the present invention, the first solid electrolyte layer (310) may have substantially the same area as the positive electrode layer (100). The second solid electrolyte layer (320) may have substantially the same area as the negative electrode layer (200).

[0103] Referring to FIGS. 1 and 2, the first solid electrolyte layer (310) may have a first width (W1) in the first direction (D1). The second solid electrolyte layer (320) may have a second width (W2) in the first direction (D1). The first width (W1) may be smaller than the second width (W2).

[0104] The difference between the second width (W2) and the first width (W1) may be 10 μm or less. Specifically, the difference between the second width (W2) and the first width (W1) may be 8 μm or less, 5 μm or less, or 3 μm or less. The difference between the second width (W2) and the first width (W1) may be 0.1 μm or more, 0.5 μm or more, or 1 μm or more. If the above numerical range is exceeded, the size of the positive electrode layer (100) becomes relatively small, so the discharge capacity may be lowered and the energy density of the all-solid-state battery (10) may be reduced. If the above numerical range is not reached, it may be difficult to suppress the formation of lithium dendrites in the negative electrode, which may cause a short circuit.

[0105] The ratio (W2 / W1) of the second width (W2) to the first width (W1) may be 1 to 1.6. Specifically, the ratio (W2 / W1) of the second width (W2) to the first width (W1) may be 1 to 1.5, 1 to 1.4, 1 to 1.3, 1 to 1.2, or 1 to 1.1.

[0106] When the ratio (W2 / W1) of the second width (W2) to the first width (W1) exceeds the above numerical range, the energy density of the all-solid-state battery (10) is reduced.

[0107]

[0108] Referring to FIGS. 1 and 2, the first solid electrolyte layer (310) may have a fourth width (W4) in the second direction (D2). The second solid electrolyte layer (320) may have a fifth width (W5) in the second direction (D2). The fourth width (W4) may be smaller than the fifth width (W5).

[0109] The difference between the fourth width (W4) and the fifth width (W5) may be 10 μm or less. Specifically, the difference between the fourth width (W4) and the fifth width (W5) may be 8 μm or less, 5 μm or less, or 3 μm or less. The difference between the fifth width (W5) and the fourth width (W4) may be 0.1 μm or more, 0.5 μm or more, or 1 μm or more. If the above numerical range is exceeded, the size of the positive electrode layer (100) becomes relatively small, so the discharge capacity may be lowered and the energy density of the all-solid-state battery (10) may be reduced. If the above numerical range is not reached, it may be difficult to suppress the formation of lithium dendrites in the negative electrode, which may cause a short circuit.

[0110] The ratio (W5 / W4) of the fifth width (W5) to the fourth width (W4) may be 1 to 1.6. Specifically, the ratio (W5 / W4) of the fifth width (W5) to the fourth width (W4) may be 1 to 1.5, 1 to 1.4, 1 to 1.3, 1 to 1.2, or 1 to 1.1.

[0111] When the ratio (W5 / W4) of the fifth width (W5) to the fourth width (W4) exceeds the above numerical range, the energy density of the all-solid-state battery (10) is reduced.

[0112]

[0113] Referring to FIGS. 1 and 2, the third width (W3) may be smaller than the second width (W2) and the fifth width (W5). The third width (W3) may have the same size as the first width (W1) and the fourth width (W4).

[0114] The difference between the third width (W3) and the second width (W2) may be 10 μm or less. Specifically, the difference between the third width (W3) and the second width (W2) may be 8 μm or less, 5 μm or less, or 3 μm or less. The difference between the third width (W3) and the second width (W2) may be 0.1 μm or more, 0.5 μm or more, or 1 μm or more. If it does not fall within the above numerical range, it may be difficult to lower the interface resistance between the first solid electrolyte layer (310) and the second solid electrolyte layer (320).

[0115]

[0116] Figure 3 is a cross-sectional view illustrating an all-solid-state battery according to another embodiment of the present invention. In this embodiment, detailed descriptions of technical features that overlap with those previously described with reference to Figures 1 and 2 will be omitted, and differences will be described in detail.

[0117] Referring to FIG. 3, the negative electrode layer (200) of the all-solid-state battery (10) may further include a lithium metal layer (400) between the negative electrode current collector (210) and the negative electrode coating layer (220). The thickness of the lithium metal layer (400) may further increase when the all-solid-state battery (10) is charged. The negative electrode coating layer (220) serves as a protective layer for the lithium metal layer (400), and at the same time, may suppress the growth of lithium dendrites from the lithium metal layer (400).

[0118] The lithium metal layer (400) may be a metal thin film containing lithium or a lithium alloy. The lithium alloy may include, but is not limited to, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, etc., and any lithium alloy may be used. The lithium metal layer (400) may contain one of these alloys or lithium. Alternatively, the lithium metal layer (400) may contain various types of alloys.

[0119] The lithium metal layer (400) may have a sixth width (W6) in the first direction (D1). The sixth width (W6) may be equal to or greater than the first width (W1). The sixth width (W6) may be equal to or less than the second width (W2). For example, the sixth width (W6) may be greater than the first width (W1) and less than the second width (W2).

[0120] Referring to FIG. 4, the all-solid-state battery (10) may further include an inert member (INM) surrounding the side surfaces of the positive electrode layer (100), the first solid electrolyte layer (310), and the interlayer (330), and in contact with the second solid electrolyte layer (320).

[0121] The present invention can prevent cracking of the solid electrolyte layer (300) during manufacturing and / or charging / discharging of an all-solid-state battery (10) by including the above-described inert member (INM), and as a result, the cycle characteristics of the all-solid-state battery (20) can be improved.

[0122] The above inert material (INM) may include at least one of pulp fibers, glass fibers, aluminum hydroxide (Al(OH)3) and a polymer binder.

[0123]

[0124] Figure 5 is a cross-sectional view illustrating an all-solid-state battery according to another embodiment of the present invention. In this embodiment, detailed descriptions of technical features that overlap with those previously described with reference to Figures 1 to 4 will be omitted, and differences will be described in detail.

[0125] Referring to FIGS. 1 and 5, the bi-cell all-solid-state battery (20) may include a first mono-cell (510) and a second mono-cell (520).

[0126] Each of the first and second monocells (510, 520) may include a positive electrode layer (100), a negative electrode layer (200), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). The solid electrolyte layer (300) of each of the first and second monocells (510, 520) may include a first solid electrolyte layer (310) adjacent to the positive electrode layer (100) and having a first width (W1) and a first thickness (t1), a second solid electrolyte layer (320) adjacent to the negative electrode layer (200) and having a second width (W2) and a second thickness (t2), and an interlayer disposed between the first solid electrolyte layer and the second solid electrolyte layer and having a third width (W3) and a third thickness (t3). The second width (W2) may be larger than the first width (W1), and the second thickness (t2) may be larger than the first thickness (t1). The third thickness (t3) may be 1 µm to 10 µm, and the sum of the first thickness (t1), the second thickness (t2), and the third thickness (t3) may be 10 µm to 60 µm. The third width (W3) may be smaller than the second width (W2), and the difference between the second width (W2) and the third width (W3) may be 1 µm to 10 µm.

[0127] The above interlayer (330) may include a polyethylene oxide-based binder, a vinylidene fluoride-based binder, and a lithium salt. The interlayer (330) may have a molar ratio of ethylene oxide (EO) and lithium (Li) of 1:1 to 100:1.

[0128] The second monocell (520) may be arranged symmetrically vertically with respect to the first monocell (510). The anode layer (100) of the first monocell (510) and the anode layer (100) of the second monocell (520) may face each other.

[0129]

[0130] Figure 6 is a cross-sectional view illustrating an all-solid-state battery according to another embodiment of the present invention. In this embodiment, detailed descriptions of technical features that overlap with those previously described with reference to Figures 1 to 5 will be omitted, and differences will be described in detail.

[0131] Referring to FIG. 6, the bi-cell all-solid-state battery (20) may further include an elastic member (ELP) disposed on one surface of the negative electrode layer (200). The elastic member (ELP) may be composed of members capable of absorbing volume changes (expansion) of the all-solid-state battery (20) due to charge and discharge and capable of elastic deformation, and more specifically, may be composed of a material having a lower elastic modulus than the positive electrode current collector and the negative electrode current collector. The material constituting the elastic member (ELP) may have a slope of a stress-displacement curve of 200 MPa or less at a displacement of 80% or less. Specifically, the material constituting the elastic member (ELP) may have a slope of a stress-displacement curve of 50 MPa or less at a displacement of 80% or less, and may have a slope of 10 MPa or less at a displacement of 50% or less.

[0132] The material of the above elastic member (ELP) may include, but is not limited to, epoxy resin, acrylic resin, polyimide resin, polyester resin, polypropylene resin, polyamide resin, polystyrene resin, polyvinyl chloride resin, polycarbonate resin, fluororesin such as PTFE, silicone rubber, etc. Each elastic member (ELP) may be composed of a single material, or may be composed of a combination of multiple materials. In addition, each elastic member (ELP) may include the same material, or may include different materials. In addition, the elastic member (ELP) may include an insulating material, and may insulate between each bi-cell all-solid-state battery (20). The insulating material may have a surface resistance of 1.0*10 17 Ω·cm 2 It may be an ideal, and specifically, it may be a fluororesin such as PTFE or silicone rubber.

[0133] Since an elastic member (ELP) is arranged between each of the bi-cell all-solid-state batteries (20), the pressure generated when the all-solid-state batteries (20) are charged and expanded can be distributed, thereby reducing the unevenness of the pressure applied to each all-solid-state battery (20) by charging and discharging. In addition, this can suppress cracking or deformation of the electrolyte layer that may occur as charging and discharging are repeated, and can suppress deterioration of battery characteristics such as cycle characteristics.

[0134] Figure 7 is a cross-sectional view illustrating an all-solid-state battery according to another embodiment of the present invention. In this embodiment, detailed descriptions of technical features that overlap with those previously described with reference to Figures 1 to 6 will be omitted, and differences will be described in detail.

[0135]

[0136] Referring to FIG. 7, the all-solid-state battery (20) may further include an inert member (INM) disposed on one side of the positive electrode layer (100), the first solid electrolyte (310), and the interlayer (330).

[0137] The inert member (INM) surrounds the side surfaces of the positive electrode layer (100), the first solid electrolyte layer (310), and the interlayer (330) of each of the first monocell (510) and the second monocell (520), and can be in contact with the second solid electrolyte layer (320).

[0138] By including an inert material (INM), cracking of the solid electrolyte layer (300) can be prevented during manufacturing and / or charging / discharging of the all-solid-state battery (20), and as a result, the cycle characteristics of the all-solid-state battery (20) can be improved.

[0139] The above inert member (INM) may include one or more selected from pulp fibers, glass fibers, aluminum hydroxide (Al(OH)3) and a polymer binder.

[0140] The above inert member (INM) may be placed between the second solid electrolyte layer (320) of the first monocell (510) and the second solid electrolyte layer (320) of the second monocell (520). By including the inert member (INM), uniform pressurization is enabled during the manufacturing process of the all-solid-state battery (20), thereby preventing cracking of the solid electrolyte layer (300), and consequently improving the cycle characteristics of the all-solid-state battery (20).

[0141] The thickness of the inert member (INM) may be equal to the sum of the thicknesses of the first solid electrolyte layer (310), the interlayer (330), and the positive electrode layer (100) of the first monocell (510). The thickness of the inert member (INM) may be equal to the sum of the thicknesses of the first solid electrolyte layer (310), the interlayer (330), and the positive electrode layer (100) of the second monocell (520).

[0142] If the thickness of the inert member (INM) is less than the sum of the thicknesses of the first solid electrolyte layer (310), the interlayer (330), and the positive electrode layer (100), appropriate pressure may not be applied to the side of the second solid electrolyte layer (320), and thus cracks may occur in the solid electrolyte layer (300). If the thickness of the inert member (INM) is greater than the sum of the thicknesses of the first solid electrolyte layer (310), the interlayer (330), and the positive electrode layer (100), the positive electrode layer (100) and the first solid electrolyte layer (310) may not be sufficiently pressurized.

[0143]

[0144] An all-solid-state battery (10) according to one embodiment of the present invention can be manufactured by stacking a positive electrode layer (100) and a first solid electrolyte layer (310), then applying a first pressure to form a positive electrode laminate, stacking a negative electrode layer (200) and the second solid electrolyte layer (320), then applying a second pressure to form a negative electrode laminate, then stacking the positive electrode laminate and the interlayer, and combining the interlayer and the negative electrode laminate so that the first solid electrolyte layer and the second solid electrolyte layer are in contact with each other.

[0145] The present invention manufactures a positive electrode laminate and a negative electrode laminate by applying separate pressurization methods, thereby allowing the first pressure and the second pressure to be controlled differently. This allows a relatively lower pressure to be applied to a laminate that has weak mechanical strength or is structurally unbalanced among the positive electrode laminate and the negative electrode laminate, and thus may be damaged when pressurized at high pressure. The first pressure may be greater than the second pressure.

[0146] The formation of the above-described positive and negative electrode laminates may include a pressing process using a roll press. However, this method is not necessarily limited to this method, and any pressing process applicable in the relevant technical field may be applied. For example, pressing processes such as a hydraulic plate press and a warm isostatic press may be applied.

[0147] When roll press is applied during the formation process of the above-mentioned positive electrode laminate, the linear pressure of the first pressure may be 1 ton / cm to 5 ton / cm. Specifically, the linear pressure of the first pressure may be 1.5 ton / cm to 4 ton / cm, 2.0 ton / cm to 3.5 ton / cm, or 2.5 ton / cm to 3.0 ton / cm.

[0148] When roll press is applied during the formation process of the above-mentioned negative electrode laminate, the linear pressure of the second pressure may be 1 ton / cm to 4 ton / cm. Specifically, the linear pressure of the first pressure may be 1.5 ton / cm to 3.5 ton / cm, 1.5 ton / cm to 2.5 ton / cm, or 1.5 ton / cm to 2 ton / cm.

[0149] The above pressurization process can be carried out at a relatively high temperature. Specifically, the pressurization process can be carried out at 60 to 150°C, 80 to 130°C, or 100 to 125°C.

[0150] Forming the above positive electrode laminate and negative electrode laminate may include a preheating process prior to the pressurizing process. Specifically, the positive electrode laminate and negative electrode laminate may be preheated to ±10°C and ±5°C, respectively, of the temperature at which the pressurizing process is performed. The preheating process may prevent damage to the positive electrode laminate and negative electrode laminate due to rapid temperature changes during the high-temperature pressurizing process.

[0151] In another embodiment of the present invention, in a method for manufacturing an all-solid-state battery, forming a positive electrode laminate includes laminating a first functional layer on a first solid electrolyte layer before applying the first pressure, forming a negative electrode laminate includes laminating a second functional layer on the second solid electrolyte layer before applying the second pressure, and may further include removing the first functional layer and the second functional layer before combining the positive electrode laminate and the negative electrode laminate. The first functional layer and the second functional layer can prevent damage to the solid electrolyte by preventing the solid electrolyte layer from being directly exposed during a high-temperature pressurization process.

[0152] The first functional layer and the second functional layer may include a plate or foil containing indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The first functional layer (FNL1) and the second functional layer (FNL2) may include polyethylene terephthalate (PET), polycarbonate (PC), polyimide (PI), or a mixture thereof.

[0153] The lamination of the above-mentioned positive electrode laminate and the above-mentioned interlayer can be performed using a bonding agent. Then, the above-mentioned negative electrode laminate, the above-mentioned interlayer, and the above-mentioned positive electrode laminate can be laminated in this order using a bonding agent.

[0154] Referring to FIG. 8, an all-solid-state battery (10) according to one embodiment of the present invention can be manufactured by combining the positive electrode laminate and the negative electrode laminate so that the interlayer (330) and the second solid electrolyte layer (320) are in contact with each other, and applying a third pressure.

[0155] The formation of the above-described positive and negative electrode laminates may include a pressurizing process using a hydraulic plate press. However, this method is not necessarily limited to this method, and any pressurizing process applicable in the relevant technical field may be applied. For example, pressurizing processes such as roll press and warm isostatic press may be applied.

[0156] The third pressure may be 2 MPa or more. Specifically, the third pressure may be 2.5 MPa or more, 3 MPa or more, or 3.5 MPa or more. The third pressure may be 100 MPa or less. Specifically, the third pressure may be 20 MPa or less, 10 MPa or less, 5 MPa or less, or 4 MPa or less.

[0157]

[0158] Figure 9 is a conceptual diagram illustrating a method for manufacturing an all-solid-state battery according to another embodiment of the present invention. In this embodiment, detailed descriptions of technical features that overlap with those previously described with reference to Figures 7 and 8 will be omitted, and differences will be described in detail.

[0159] An all-solid-state battery according to another embodiment of the present invention may include first and second monocells (510, 520). The second monocell (520) may be arranged symmetrically vertically with the first monocell (510) and joined by pressurization.

[0160]

[0161] Hereinafter, the present invention will be described in more detail through examples. However, these examples are intended to exemplify the present invention and the scope of the present invention is not limited to these examples.

[0162]

[0163] Example 1

[0164] (Cathode layer manufacturing)

[0165] A 10 ㎛ thick SUS foil was prepared as a negative electrode current collector. In addition, carbon black (CB) with a primary particle diameter of approximately 30 nm and silver (Ag) particles with an average particle diameter (D50) of approximately 60 nm were prepared as negative electrode active materials. 4 g of a mixed powder of carbon black (CB) and silver (Ag) particles in a weight ratio of 3:1 was placed in a container, and 4 g of an NMP solution containing 7 wt% PVDF binder (#9300 from Kureha) was added thereto to prepare a mixed solution. Subsequently, a slurry was prepared by stirring the mixed solution while adding NMP little by little to the mixed solution. The prepared slurry was coated on a Ni sheet using a bar coater at a concentration of 0.8 mg / cm. 2 and dried in the air at 80°C for 10 minutes. The laminate thus obtained was vacuum dried at 40°C for 10 hours. The dried laminate was flattened on the surface of the first negative electrode active material layer of the laminate by applying a pressure of 1.5 ton / cm using a cold roll press. The negative electrode layer was manufactured by the above process. The thickness of the first negative electrode active material layer included in the negative electrode layer was approximately 7 μm. The areas of the first negative electrode active material layer and the negative electrode current collector were the same.

[0166]

[0167] (Anode layer manufacturing)

[0168] LiNi coated with Li2O-ZrO2 (LZO) as a cathode active material 0.8 Co 0.15 Mn 0.05 O2(NCM) was prepared. The LZO-coated cathode active material was prepared according to the method disclosed in Korean Patent Publication No. 10-2016-0064942. Li6PS5Cl (D50 = 0.5 μm, crystalline) in the form of an argyrodite crystal was prepared as a solid electrolyte. Polytetrafluoroethylene (PTFE) binder was prepared as a binder. Carbon nanofibers (CNF) were prepared as a conductive agent. These materials were mixed with a xylene solvent in a weight ratio of cathode active material: solid electrolyte: conductive agent: binder = 84:11.5:3:1.5, and the slurry was molded into a sheet shape, and then vacuum-dried at 40°C for 8 hours to prepare a cathode sheet. The manufactured positive electrode sheets were placed on both sides of a positive electrode current collector made of aluminum foil coated on both sides, and a positive electrode layer was manufactured by applying a pressure of 2.0 ton / cm using a heated roll press at 120°C. The total thickness of the positive electrode layer was approximately 220 μm. The thickness of each positive electrode active material layer was approximately 96 μm, and the thickness of the carbon-coated aluminum foil was approximately 28 μm. The areas of the positive electrode active material layer and the positive electrode current collector were the same.

[0169]

[0170] (Manufacturing of solid electrolyte layer, dry)

[0171] A mixture was prepared by adding 1 part by weight of a polytetrafluoroethylene (PTFE) first binder and 1 part by weight of a polyvinylidene fluoride (PVDF) second binder to 98 parts by weight of a Li6PS5Cl sulfide-based solid electrolyte (D50 = 10 μm, crystalline) which is an argyrodite crystal, and mixing them in a grind mixer. The prepared mixture was added to a mortar heated to 80°C and stirred to prepare a dough. The prepared dough was passed through a roller and formed into a sheet shape to prepare a solid electrolyte membrane of a certain thickness. A solid electrolyte layer was manufactured by the above process. The above solid electrolyte layers were prepared as a first solid electrolyte layer having substantially the same area as the positive electrode layer, and a second solid electrolyte layer having substantially the same area as the negative electrode layer, respectively. The elastic modulus of the sulfide-based solid electrolyte was about 15 GPa to 30 GPa.

[0172] The thickness (t1) of the first solid electrolyte layer manufactured was 20 ㎛, and the thickness (t2) of the second solid electrolyte layer manufactured was 40 ㎛.

[0173]

[0174] (Manufacture of the intermediate layer) - PEO-LiTFSI (SEC)

[0175] PEO (600,000 g / mol) 1.97 g and LiTFSI (287.09 g / mol) 0.854 g are each weighed, and PVDF 1.31 g is weighed. PVDF is dissolved in NMP, and LiTFSI is dissolved in the solution. Then, PEO is added and mixed overnight to prepare a mixture. The mixed content of PEO and PVDF in the mixture is 40 wt%. Then, the mixture is applied to the substrate. Then, 80 o Dry in a C Convection oven at 120 oC, an interlayer is formed when vacuum drying is performed for 6 hours. At this time, the ratio of EO / Li is 5. The thickness (t3) of the formed interlayer is 10 ㎛.

[0176]

[0177] (Manufacturing of all-solid-state batteries)

[0178] A cathode laminate was manufactured by laminating the above cathode layer and the first solid electrolyte layer.

[0179] The laminated anode laminate can be pressurized under conditions of a pressure of 2.5 ton / cm and a temperature of 120°C. A cathode laminate was manufactured by laminating the cathode layer and the second solid electrolyte layer. The laminated cathode laminate can be pressurized under conditions of a pressure of 2.0 ton / cm and a temperature of 120°C.

[0180]

[0181] The above-mentioned negative electrode laminate, the above-mentioned intermediate layer, and the above-mentioned positive electrode laminate were laminated in that order using a bonding agent, and then pressurized under conditions of a pressure of 0.5 ton / cm and a temperature of 120°C to finally manufacture an all-solid-state battery.

[0182] A 300㎛ thick buffer pad made of acrylic foam or polyurethane foam was attached to one side of the cathode layer.

[0183]

[0184] Example 2

[0185] An all-solid-state battery was manufactured using the same method as Example 1, except that the ratio of EO / Li was changed to 15 when manufacturing the interlayer.

[0186]

[0187] Example 3

[0188] An all-solid-state battery was manufactured using the same method as Example 1, except that the ratio of EO / Li was changed to 25 when manufacturing the interlayer.

[0189]

[0190] Example 4

[0191] An all-solid-state battery was manufactured using the same method as Example 1, except that the thickness (t3) of the interlayer was 5 ㎛.

[0192]

[0193] Example 5

[0194] An all-solid-state battery was manufactured in the same manner as Example 1, except that the thickness (t3) of the interlayer was 5 μm and the ratio of EO / Li was changed to 15.

[0195]

[0196] Example 6

[0197] An all-solid-state battery was manufactured in the same manner as Example 1, except that the thickness (t3) of the interlayer was 5 μm and the ratio of EO / Li was changed to 25.

[0198]

[0199] Example 7

[0200] An all-solid-state battery was manufactured using the same method as Example 1, except that the thickness (t3) of the interlayer was 1 ㎛.

[0201]

[0202] Example 8

[0203] An all-solid-state battery was manufactured in the same manner as Example 1, except that the thickness (t3) of the interlayer was 1 ㎛ and the ratio of EO / Li was changed to 15.

[0204]

[0205] Example 9

[0206] An all-solid-state battery was manufactured in the same manner as Example 1, except that the thickness (t3) of the interlayer was 1 μm and the ratio of EO / Li was changed to 25.

[0207]

[0208] Comparative Example 1

[0209] An all-solid-state battery was manufactured in the same manner as Example 1, except that the interlayer was not used.

[0210]

[0211] The energy density, total capacity, and short-circuit occurrence time of the all-solid-state secondary batteries manufactured in the examples and comparative examples were evaluated according to the thickness and EO / Li ratio.

[0212]

[0213] Evaluation Example 1: Energy Density

[0214] The energy density (Wh / L) of the all-solid-state batteries manufactured by the examples and comparative examples was measured using a standard calculation method (based on an 80Ah stack cell, capacity*standard voltage / volume). The results of the energy density evaluation experiment are shown in Table 1 below: if the energy density is 900 Wh / L or higher, it is “excellent,” if it is 800 Wh / L to 900 Wh / L, it is “good,” if it is 600 Wh / L to 800 Wh / L, it is “fair,” and if it is 600 Wh / L or less, it is “poor.”

[0215]

[0216] Evaluation Example 2: Initial Capacity

[0217] The all-solid-state batteries manufactured by the Examples and Comparative Examples were evaluated by the following charge-discharge tests. The charge-discharge tests were performed by placing the all-solid-state batteries in a thermostatic chamber at 45°C. The first cycle was performed by charging at a constant current of 0.1C until the battery voltage reached 4.25 V, and then charging was performed at a constant voltage of 4.25 V with a 0.05C cut-off condition when 4.25 V was reached. Subsequently, discharging was performed at a constant current of 0.1C until the battery voltage reached 2.5 V. The discharge capacity of the first cycle was taken as the initial capacity. The results are shown in Table 1 below.

[0218]

[0219] Evaluation Example 3: Life Characteristics Evaluation

[0220] The all-solid-state batteries manufactured by the Examples and Comparative Examples were evaluated by the following charge-discharge tests. The charge-discharge tests were performed by placing the all-solid-state batteries in a thermostatic chamber at 45°C. In the first cycle, the batteries were charged at a constant current of 0.33C until the battery voltage reached 4.25 V, and when 4.25 V was reached, constant voltage charging was performed at 4.25 V with a 0.1C cut-off condition. Subsequently, the batteries were discharged at a constant current of 0.33C until the battery voltage reached 2.5 V. From the second cycle onwards, charging and discharging were performed up to 250 cycles under the same conditions as the first cycle. As the number of cycles at which a short circuit occurs increases, this means that the life characteristics improve. The results of the charge-discharge tests are shown in Table 1 below.

[0221]

[0222] Interlayer Energy Density Evaluation Application Thickness (t3) EO / Li Initial Capacity (mAh / g) Short Circuit Occurrence Time (Times) Example 1 Application 105 fair 185.4 > 250 Example 2 Application 1015 fair 180 > 300 Example 3 Application 1025 fair 171.1 > 350 Example 4 Application 55 good 194.6 > 200 Example 5 Application 515 good 189 > 250 Example 6 Application 525 good 179.6 > 300 Example 7 Application 15 excellent 169.4 < 100 Example 8 Application 115 excellent 165.4 < 125 Example 9 Application 125 excellent 158.8 > 150 Comparative Example 1000 excellent 130 < 10

[0223] In Table 1 above, “>250” means that no short circuit occurs even after 250 cycles of testing.

[0224] Referring to Table 1 above, if the thickness (t3) of the interlayer is too thin, it is difficult to form an interface, and if the thickness (t3) is too thick, there is a problem of increased interface resistance. Comparative Example 1 shows that the non-application of the interlayer results in insufficient interface formation of the brittle body, resulting in poor cell performance.

[0225] According to the example, the EO / Li ratio is related to the ionic conductivity of the interlayer, and it can be seen that the higher the EO / Li ratio, the higher the ionic conductivity.

[0226] When using an interlayer according to the concept of the present invention (Examples 1 to 9), it was evaluated that the possibility of a short circuit was lower than when an interlayer was not applied (Comparative Example 1), and it was confirmed that the life characteristics were excellent.

Claims

1. Bipolar layer; cathode layer; and Including a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, The above solid electrolyte layer: A first solid electrolyte layer adjacent to the anode layer and having a first width and a first thickness; a second solid electrolyte layer adjacent to the cathode layer and having a second width and a second thickness; and An all-solid-state battery comprising an interlayer disposed between the first solid electrolyte layer and the second solid electrolyte layer and having a third width and a third thickness.

2. In paragraph 1, An all-solid-state battery, wherein the second width is greater than the first width, and the second thickness is greater than the first thickness.

3. In paragraph 1, The above interlayer is, An all-solid-state battery comprising a polyethylene oxide-based binder, a vinylidene fluoride-based binder, and a lithium salt.

4. In paragraph 1, The above interlayer is, An all-solid-state battery having a molar ratio of ethylene oxide (EO) and lithium (Li) of 1:1 to 100:

1.

5. In paragraph 1, The first thickness is 1 ㎛ to 30 ㎛, An all-solid-state battery, wherein the sum of the first thickness and the second thickness is 40 ㎛ to 60 ㎛.

6. In paragraph 1, An all-solid-state battery in which the first thickness t1 and the second thickness t2 satisfy the following equation 1: [Formula 1] 1 ≤ t2 / t1< 4.

7. In paragraph 1, The third thickness is 1 ㎛ to 10 ㎛, An all-solid-state battery, wherein the sum of the first thickness, the second thickness, and the third thickness is 10 ㎛ to 60 ㎛.

8. In paragraph 1, The above third width is smaller than the above second width, An all-solid-state battery, wherein the difference between the second width and the third width is 1 ㎛ to 10 ㎛.

9. In paragraph 1, It further includes an inert member surrounding the side surfaces of the anode layer, the first solid electrolyte layer and the interlayer, and contacting the second solid electrolyte layer; An all-solid-state battery, wherein the inert material comprises pulp fibers, glass fibers, aluminum hydroxide, and a polymer binder.

10. In paragraph 1, The above solid electrolyte layer has a fourth thickness (T), An all-solid-state battery, wherein the height at which the interlayer is located within the solid electrolyte layer satisfies the following equation 2: [Formula 2] 50 (%) ≤ (d1 / T)*100 to [(d1+d3 / )T]*100 (%) ≤80 (%) Here, d1 refers to the height of the first solid electrolyte layer in the cross-sectional view of the all-solid-state battery, and d3 refers to the height of the interlayer in the cross-sectional view of the all-solid-state battery.

11. 1st monocell; and Including a second monocell on the first monocell, The second monocell is arranged symmetrically vertically with respect to the first monocell, Each of the first and second monocells includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, The positive electrode layer of the first monocell and the positive electrode layer of the second monocell face each other, The solid electrolyte layer of each of the first and second monocells comprises: A first solid electrolyte layer adjacent to the anode layer and having a first width and a first thickness; a second solid electrolyte layer adjacent to the cathode layer and having a second width and a second thickness; and An all-solid-state battery comprising an interlayer disposed between the first solid electrolyte layer and the second solid electrolyte layer and having a third width and a third thickness.

12. In paragraph 11, An all-solid-state battery, wherein the second width is greater than the first width, and the second thickness is greater than the first thickness.

13. In paragraph 11, The above interlayer is, An all-solid-state battery comprising a polyethylene oxide-based binder, a vinylidene fluoride-based binder, and a lithium salt.

14. In paragraph 11, The above interlayer is, An all-solid-state battery having a molar ratio of ethylene oxide (EO) and lithium (Li) of 1:1 to 100:

1.

15. In paragraph 11, The third thickness is 1 ㎛ to 10 ㎛, The sum of the first thickness, the second thickness, and the third thickness is 10 ㎛ to 60 ㎛, The above third width is smaller than the above second width, An all-solid-state battery, wherein the difference between the second width and the third width is 1 ㎛ to 10 ㎛.

16. In paragraph 11, Each of the first and second monocells, It further includes an inert member surrounding the side surfaces of the anode layer, the first solid electrolyte layer and the interlayer, and contacting the second solid electrolyte layer; An all-solid-state battery, wherein the inert material comprises pulp fibers, glass fibers, aluminum hydroxide, and a polymer binder.

17. In paragraph 11, An all-solid-state battery further comprising an elastic member disposed on at least one surface of the cathode layer.

18. A method for manufacturing an all-solid-state battery, comprising: a cathode layer; a second solid electrolyte layer disposed on the cathode layer and having substantially the same area as the cathode layer; a first solid electrolyte layer disposed on the second solid electrolyte layer and having a smaller width than the second solid electrolyte layer; an interlayer disposed between the first solid electrolyte layer and the second solid electrolyte layer and having substantially the same area as the first solid electrolyte layer; and a cathode layer disposed on the first solid electrolyte layer and having substantially the same area as the first solid electrolyte layer. Laminating the above cathode layer and the first solid electrolyte layer and then applying a first pressure to form a cathode laminate; Laminating the cathode layer and the second solid electrolyte layer and then applying a second pressure to form a cathode laminate; Laminating the above-mentioned bipolar laminate and the above-mentioned interlayer; Including combining the interlayer and the negative electrode laminate so that the first solid electrolyte layer and the second solid electrolyte layer are in contact with each other, A method for manufacturing an all-solid-state battery, wherein the first pressure is greater than the second pressure.

19. In paragraph 18, Forming the above-mentioned positive electrode laminate comprises laminating a first functional layer on the first solid electrolyte layer before applying the first pressure, Forming the above cathode laminate includes laminating a second functional layer on the second solid electrolyte layer before applying the second pressure, A method for manufacturing an all-solid-state battery, further comprising removing the first functional layer and the second functional layer before combining the positive electrode laminate and the negative electrode laminate.

20. In paragraph 18, A method for manufacturing an all-solid-state battery, further comprising combining the positive electrode assembly and the negative electrode assembly so that the interlayer and the second solid electrolyte layer are in contact with each other and applying a pressure of 2 MPa to 4 MPa.

21. Preparing a plurality of all-solid-state batteries manufactured according to Article 18; and A method for manufacturing an all-solid-state battery, comprising stacking a plurality of all-solid-state batteries so as to have a vertically symmetrical structure centered on the positive electrode layer.

Images