All-solid-state battery

Abstract

The present invention relates to an all-solid-state battery. More specifically, in an all-solid-state battery according to the present invention, the cross-sectional shapes and areas of a cathode layer, a solid electrolyte layer and an anode layer are made to be identical in a unit cell in which the cathode layer, the solid electrolyte layer and the anode layer are stacked, so that structural stability can be improved, and a plurality of unit cells are stacked using a continuous cathode current collector so that battery performance such as energy density can enhanced.

Description

All-solid-state batteries

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0078669, filed June 18, 2024, and Korean Patent Application No. 10-2025-0080006, filed June 18, 2025, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to an all-solid-state battery.

[0005] Various batteries are being studied to overcome the limitations of current lithium secondary batteries in terms of battery capacity, stability, output, large-scale development, and miniaturization.

[0006] Representative examples include metal-air batteries with much larger theoretical capacity than lithium secondary batteries, all-solid-state batteries with no risk of explosion in terms of safety, supercapacitors for output, NaS batteries or RFBs (redox flow batteries) for large-scale applications, and thin film batteries for miniaturization, all of which are being continuously researched in academia and industry.

[0007] All-solid-state batteries replace the liquid electrolytes used in conventional lithium secondary batteries with solid electrolytes. Because they do not use flammable solvents, they eliminate the risk of ignition or explosion caused by decomposition reactions of conventional electrolytes, significantly improving safety. Furthermore, because lithium metal or lithium alloys can be used as a cathode material, they offer the advantage of dramatically improving the battery's energy density relative to its mass and volume.

[0008] However, in the cell assembly process for all-solid-state batteries, each electrode is individually stacked on top of a pouch, making precise alignment difficult to achieve. When stacking cells to improve energy density, using cells with such poor alignment can lead to unstable stack structures, potentially leading to cracks and short circuits.

[0009]

[0010] Figures 1a to 1c are schematic diagrams showing longitudinal cross-sections of an all-solid-state battery according to the prior art (1a: longitudinal cross-section of a unit cell, 1b: longitudinal cross-section of a stack cell, 1c: longitudinal cross-section of a stack including a cathode layer and a solid electrolyte layer).

[0011] A unit cell (100) of an all-solid-state battery according to the prior art has a structure in which a positive electrode collector (111), a positive electrode active material layer (112), a solid electrolyte layer (120), and a negative electrode layer (130) are sequentially stacked (Fig. 1a). A stack cell (200) is formed by stacking a plurality of unit cells (100), and for example, two or more unit cells (100) may be stacked (Fig. 1b). When manufacturing a unit cell (100), the area of ​​the positive electrode layer (110) including the positive electrode collector (111) and the positive electrode active material layer (112) is smaller than that of the adjacent solid electrolyte layer (120), so that it is not easy to align the solid electrolyte layer (120) on the positive electrode layer (110), and thus a misalignment may occur (Fig. 1c). In general, if the positive electrode layer is stretched and comes into contact with the negative electrode layer, or if a misalignment is formed during the assembly process and the two electrode layers meet, a short circuit occurs, so the positive electrode layer is designed to be smaller than the solid electrolyte layer that acts as a separator. In addition, after stacking the components as described above, if a crack (C) occurs in the solid electrolyte layer (120) due to a difference in the area of ​​the adjacent positive electrode active material layer (112) and the solid electrolyte layer (120) when pressurized, and the stacked structure itself collapses (D), contact between the positive electrode layer and the negative electrode layer may occur.

[0012]

[0013] Figure 2 is the structure of an all-solid-state battery disclosed in Korean Patent Publication No. 2022-0080930.

[0014] Referring to FIG. 2, it can be seen that the structural stability of the all-solid-state battery is secured by providing a spacer (50) made of a polymer in the space created because the area of ​​the negative electrode layer (40) is smaller than that of the solid electrolyte layer (30). The spacer (50) is made of a polymer including at least one selected from the group consisting of polyethylene, polyethylene naphthalate, polyethylene terephthalate, and combinations thereof. Since the spacer (50) is a different material from the negative electrode layer, when pressure is applied during the pressurizing process during the manufacture of the all-solid-state battery, cracks, etc. may occur in the spacer (50) and the solid electrolyte layer (30) that receives the load, even if the negative electrode layer (40) is not damaged even under the same pressure. This phenomenon may be particularly significant in a stack cell.

[0015] Therefore, in order to achieve high stability of all-solid-state batteries, technology development is required that can easily achieve consistent alignment during cell assembly and thereby secure structural stability.

[0016] [Prior Art Literature]

[0017] [Patent Document]

[0018] (Patent Document 1) Korean Patent Publication No. 2022-0080930

[0019] The inventors of the present invention have conducted various studies to solve the above problems and have confirmed that the structural stability of an all-solid-state battery can be secured by forming a unit cell including a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, and designing the shape and area of ​​the cross-section of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer to be identical, and that the performance of the battery can be improved by stacking multiple unit cells using a continuous positive electrode current collector.

[0020] Accordingly, an object of the present invention is to provide an all-solid-state battery with improved structural stability and performance.

[0021] In order to achieve the above purpose, the present invention is an all-solid-state battery formed by stacking a plurality of unit cells,

[0022] The unit cell includes a positive electrode layer including a positive electrode active material layer in contact with a certain area of ​​one side of a positive electrode current collector; a solid electrolyte layer having a shape surrounding one side of the positive electrode active material layer and side surfaces adjacent to the one side and formed to be in contact with the positive electrode current collector; and a negative electrode layer positioned on the solid electrolyte layer and having an area equal to that of the solid electrolyte layer.

[0023] The above multiple unit cells are stacked so that the interfaces adjacent to each other in the positive electrode current collectors and the interfaces adjacent to each other in the negative electrode layers appear alternately,

[0024] A first folding part is formed on a first side perpendicular to the direction in which the unit cells are stacked, and the first folding part includes a positive electrode current collector and an insulating layer formed on one side of the positive electrode current collector.

[0025] An all-solid-state battery is provided, wherein the first folding portion is continuously formed on the first side.

[0026] In one embodiment of the present invention, a buffer layer formed between the plurality of unit cells may be additionally included.

[0027] In one embodiment of the present invention, the space between the plurality of unit cells may be between negative current collectors or positive current collectors included in the plurality of unit cells.

[0028] In one embodiment of the present invention, the buffer layer may include at least one selected from the group consisting of silicone, gel polymer, polytetrafluoroethylene (PTFE), and polyurethane foam.

[0029] In one embodiment of the present invention, the first folding portion formed on the first side perpendicular to the direction in which the unit cells are stacked may be formed discontinuously based on the buffer layer formed between the positive electrode current collectors included in the plurality of unit cells.

[0030] In one embodiment of the present invention, the negative electrode layer includes a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector,

[0031] It may be an all-solid-state battery in which the negative active material layer is laminated so as to be in contact with the solid electrolyte layer.

[0032] In one embodiment of the present invention, the all-solid-state battery may be pouch-shaped.

[0033] The unit cell included in the all-solid-state battery of the present invention has a structure in which a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are sequentially laminated, and the shapes and cross sections of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are identical, thereby providing structural stability, and thus preventing damage such as cracks or stretching during the process of pressing and bonding during manufacturing.

[0034] In addition, by stacking multiple unit cells using a continuous type of positive electrode collector, energy density can be improved along with structural stability.

[0035] Figures 1a to 1c are schematic diagrams showing longitudinal cross-sections of an all-solid-state battery according to the prior art (1a: longitudinal cross-section of a unit cell, 1b: longitudinal cross-section of a stack cell, 1c: longitudinal cross-section of a stack including a cathode layer and a solid electrolyte layer).

[0036] Figure 2 is the structure of an all-solid-state battery disclosed in Korean Patent Publication No. 2022-0080930.

[0037] FIGS. 3a to 3c are schematic diagrams showing longitudinal cross-sections of an all-solid-state battery according to the present invention (3a: longitudinal cross-section of a unit cell, 3b: longitudinal cross-section of an all-solid-state battery, 3c: longitudinal cross-section of a laminate including a cathode layer and a solid electrolyte layer).

[0038] Figure 4 is a schematic diagram showing a manufacturing process of an all-solid-state battery according to the present invention.

[0039] FIGS. 5a to 5d are schematic diagrams of a unit cell manufacturing process according to a preferred embodiment of the present invention (5a: anode arrangement, 5b: solid electrolyte layer manufacturing, 5c: top surface and longitudinal cross-sectional schematic diagram of the manufactured solid electrolyte layer, 5d: cutting of a laminate including anode layer and solid electrolyte layer).

[0040] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0041] The terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0042]

[0043] All-solid-state batteries

[0044] The present invention relates to an all-solid-state battery.

[0045] The all-solid-state battery according to the present invention is an all-solid-state battery formed by stacking a plurality of unit cells,

[0046] The unit cell includes a positive electrode layer including a positive electrode active material layer in contact with a certain area of ​​one side of a positive electrode current collector; a solid electrolyte layer having a shape surrounding one side of the positive electrode active material layer and side surfaces adjacent to the one side and formed to be in contact with the positive electrode current collector; and a negative electrode layer positioned on the solid electrolyte layer and having an area equal to that of the solid electrolyte layer.

[0047] The above multiple unit cells are stacked so that the interfaces adjacent to each other in the positive electrode current collectors and the interfaces adjacent to each other in the negative electrode layers appear alternately,

[0048] A first folding part is formed on a first side perpendicular to the direction in which the unit cells are stacked, and the first folding part includes a positive electrode current collector and an insulating layer formed on one side of the positive electrode current collector.

[0049] The above first folding portion is formed continuously on the first side.

[0050]

[0051] FIGS. 3a to 3c are schematic diagrams showing cross-sections of an all-solid-state battery according to one embodiment of the present invention (3a: cross-section of a unit cell, 3b: cross-section of an all-solid-state battery, 3c: cross-section of a laminate including a cathode layer and a solid electrolyte layer).

[0052] Referring to FIGS. 3a to 3c, a unit cell (100) included in an all-solid-state battery (1) has a structure in which a positive electrode collector (111), a positive electrode active material layer (112), a solid electrolyte layer (120), and a negative electrode layer (130) are sequentially laminated.

[0053] The positive electrode active material layer (112) is in contact with one side of the positive electrode current collector (111), and is in a form in which it is in contact with a certain area of ​​the one side. In the positive electrode active material layer (112), the other side opposite to the one side in contact with the positive electrode current collector (111) and four side surfaces adjacent to the other side are surrounded by a solid electrolyte layer (120). At this time, the one side of the positive electrode active material layer (112) in contact with the positive electrode current collector (111) may be referred to as the first side, and the other side may be referred to as the second side.

[0054]

[0055] The unit cell (100) may have a rectangular parallelepiped shape, and the cross-sections of the positive electrode current collector (111), the solid electrolyte layer (120), and the negative electrode layer (130) have the same area and shape. In addition, the area and shape of the cross-section of the positive electrode active material layer (112) surrounded by the solid electrolyte layer (120) may be the same as the area and shape of the positive electrode current collector (111) in addition to the cross-section of the positive electrode active material layer (112) and the cross-section of the solid electrolyte layer (120) (Fig. 3a).

[0056] Since the unit cell (100) has a rectangular parallelepiped shape and is structurally stable, it is easy to align the unit cell (100) when manufacturing it, and as described above, phenomena such as cracks, elongation, or cell shorts can be prevented even when pressurizing the components after laminating them (Fig. 3c).

[0057]

[0058] In addition, the all-solid-state battery (1) may be formed by stacking a plurality of unit cells (100). At this time, the plurality of unit cells (100) may be stacked so that the negative electrode layers (130) are adjacent to each other, and among the negative electrode layers (130), the negative electrode current collectors (131) may be stacked so that they are adjacent to each other. In addition, the plurality of unit cells (100) may be stacked so that the positive electrode current collectors (111) are adjacent to each other. The stacking may be such that the interfaces where the negative electrode current collectors (131) are adjacent to each other and the interfaces where the positive electrode current collectors (131) are adjacent to each other appear alternately.

[0059]

[0060] In addition, a first folding portion (F1) may be formed on a first side perpendicular to the direction in which the unit cells (100) are stacked. The first folding portion (F1) includes a positive electrode collector (111) and is formed continuously on the positive electrode collector (111) included in the unit cell (100). In addition, an insulating layer (400) may be formed on one side of the positive electrode collector (111) in the first folding portion (F1). Specifically, the insulating layer (400) may be formed adjacent to the unit cell (100) in the first folding portion (F1). In addition, a portion where positive electrode collectors (111) are stacked on a second side opposite to the first side may be referred to as a second folding portion (F2). When stacking the unit cells (100), Z-folding and stacking may be performed using a positive electrode collector (111) of a continuous form. In addition, the first folding part (F1) and the second folding part (F2) formed in the lamination process using the continuous type positive electrode collector (111) are laminated so as not to protrude outward, so that the outer surface of the unit cell (100) in the lamination direction can form a straight line. In other words, the size and shape of the cross-section at any point of the laminated unit cell (100) are the same, so that structural stability can be ensured, and damage such as cracks or stretching can be prevented even in the process of pressing and bonding during the manufacturing process of the all-solid-state battery. If the first folding part (F1) or the second folding part (F2) formed during the lamination process is in a form that protrudes outward, the protrusions may be damaged due to the difference in size when pressure is applied during the manufacturing process of the all-solid-state battery. The insulating layer (400) is intended to prevent a short circuit from occurring on the side of the unit cell (100) and may include a material having insulating properties. For example, the insulating layer (400) may include at least one selected from the group consisting of thermoplastic polymers, acrylic resins, and silicone resins.The thermoplastic polymer may include at least one selected from the group consisting of polyolefins such as polyimide (PI), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). In addition, the polypropylene may be in the form of a cast polypropylene (CPP) film.

[0061] In addition, the first folding portion (F1) may be formed continuously over the entire first side, and the second folding portion (F2) may be formed on the side of the interface where the positive electrode collectors (111) of the unit cells (100) are adjacent to each other on the second side. That is, the first folding portion (F1) may be formed adjacent to two unit cells, and the second folding portion (F2) may be formed adjacent to two positive electrode collectors (111) included in two unit cells.

[0062] Or, as described later, when the buffer layer (300) is formed, the first folding portion (F1) may be formed discontinuously based on the buffer layer (300) formed between the positive electrode collectors (111).

[0063]

[0064] In addition, the all-solid-state battery (1) may additionally include a buffer layer (300) formed between unit cells (100). As described above, the unit cells (100) may be laminated with negative current collectors (131) adjacent to each other or with positive current collectors (111) adjacent to each other, so the buffer layer (300) may be formed between negative current collectors (131) and / or between positive current collectors (111).

[0065]

[0066] A buffer layer (300) can be added during the unit cell (100) lamination process, and can improve the uniformity of pressurization. In this case, uniformity of pressurization means that when the buffer layer is present after laminating the unit cells, the pressurization can be uniformly performed.

[0067]

[0068] In addition, the buffer layer may include at least one selected from the group consisting of silicone, gel polymer, polytetrafluoroethylene (PTFE), and polyurethane foam. In addition, the silicone may be silicone foam and / or silicone rubber. However, the material of the buffer layer is not limited thereto, and a wide range of materials that can be used as a buffer layer material of a pack and / or module may be used.

[0069] In addition, the thickness of the buffer layer may be 50 ㎛ to 15 mm. The thickness of the buffer layer may be optimized in consideration of the range in which it can function as a buffer layer. Specifically, the thickness of the buffer layer may be 50 ㎛ or more, 100 ㎛ or more, 200 ㎛ or more, 300 ㎛ or more, 400 ㎛ or more, 500 ㎛ or more, 600 ㎛ or more, 700 ㎛ or more, 800 ㎛ or more, 900 ㎛ or more, or 1 mm or more, and may be 15 mm or less, 14 mm or less, 13 mm or less, 12 mm or less, 11 mm or less, 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, or 5 mm or less.

[0070]

[0071] Additionally, the shape and size of the cross-section of the buffer layer may be the same as the shape and size of the cross-section of the unit cell.

[0072] In addition, when the buffer layer is formed, the first folding portion may be formed discontinuously based on the buffer layer. That is, the first folding portion may not be formed on the first side corresponding to the portion where the buffer layer is formed.

[0073]

[0074] In one embodiment of the present invention, the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer formed on one surface of the positive electrode current collector.

[0075] The above positive electrode current collector supports the positive electrode active material layer and serves to transfer electrons between the external conductor and the positive electrode active material layer.

[0076] In addition, the positive electrode current collector is not particularly limited as long as it has high electronic conductivity without causing chemical changes in the all-solid-state battery. For example, the positive electrode current collector may be made of aluminum, nickel, titanium, palladium, calcined carbon, copper, stainless steel, copper or stainless steel surface-treated with carbon, nickel, silver, etc., or an aluminum-cadmium alloy.

[0077] In addition, the positive electrode current collector may have a fine rough structure on its surface or may employ a three-dimensional porous structure to strengthen the bonding strength with the positive electrode active material layer. Accordingly, the positive electrode current collector may include various forms such as a film, sheet, foil, mesh, net, porous body, foam, or non-woven fabric.

[0078]

[0079] The above positive electrode active material layer may be formed with an area smaller than the positive electrode current collector and positioned on the positive electrode current collector.

[0080] The above positive electrode active material layer includes a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0081] In addition, the positive electrode active material is not particularly limited as long as it is a material capable of reversibly absorbing and releasing lithium ions, and examples thereof include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and Li[Ni x Co y Mn z M v ]O2 (wherein M is one or two or more elements selected from the group consisting of Al, Ga, and In; 0.3≤x<1.0, 0≤y, z≤0.5, 0≤v≤0.1, x+y+z+v=1), Li(Li a M b-a-b' M' b' )O 2-c A c (In the above formula, 0≤a≤0.2, 0.6≤b≤1, 0≤b'≤0.2, 0≤c≤0.2; M includes at least one selected from the group consisting of Mn and Ni, Co, Fe, Cr, V, Cu, Zn and Ti; M' is at least one selected from the group consisting of Al, Mg and B, and A is at least one selected from the group consisting of P, F, S and N.) layered compounds or compounds substituted with one or more transition metals; chemical formula Li 1+y Mn 2-y Lithium manganese oxides such as O4 (where y is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-y Ni-site type lithium nickel oxide represented by MyO2 (wherein, M=Co, Mn, Al, Cu, Fe, Mg, B or Ga, and y is 0.01 to 0.3); chemical formula LiMn 2-y M yLithium manganese composite oxides represented by O2 (wherein M is Co, Ni, Fe, Cr, Zn or Ta, and y is 0.01 to 0.1) or Li2Mn3MO8 (wherein M is Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of Li in the chemical formula is replaced by an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, etc., but are not limited thereto.

[0082] In addition, the positive electrode active material may be included in an amount of 60 to 90 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 60 wt%, 65 wt% or more, or 70 wt% or more, and may be 90 wt% or less, 85 wt% or less, 80 wt% or less, or 75 wt% or less. If the content of the positive electrode active material is less than 60 wt%, battery performance may deteriorate, and if it is more than 90 wt%, mass transfer resistance may increase.

[0083] In addition, the solid electrolyte may have an argyrodite structure, and specifically, may include a sulfide-based solid electrolyte, a halide-based solid electrolyte, or an oxide-based solid electrolyte.

[0084] The above sulfide-based solid electrolyte may include a compound represented by the following chemical formula 1 or a mixture thereof:

[0085] <Chemical Formula 1>

[0086] Li a M b S c X d

[0087] In the above chemical formula 1, M is selected from P, Sn, Sb, As, and Ge;

[0088] wherein X is selected from Cl, Br and I,

[0089] 5 ≤ a ≤ 7.5, 0.5 < b ≤ 1.5, 4 < c ≤ 6, and 0.5 < d ≤ 2.

[0090] The above halide-based solid electrolyte may be represented by the following chemical formula 2:

[0091] <Chemical Formula 2>

[0092] Li 6-3a M a Br b Cl c

[0093] In the above chemical formula 2, M is a metal other than Li, and a is 0 <a<2 이고, b는 0≤b≤6 이고, c는 0≤c≤6 이며, b+c=6 이다.

[0094] For example, the halide solid electrolyte may include at least one selected from the group consisting of Li3YBr6, Li3YCl6, and Li3YBr2Cl4.

[0095] The above oxide-based solid electrolyte is Li 3x La 2 / 3-x LLT system with perovskite structure such as TiO3, Li 14 LISICON, Li such as Zn(GeO4)4 1.3 Al 0.3 Ti 1.7 LATP series such as (PO4)3, (Li 1+x Ge 2-x Al x LAGP systems such as (PO4)3) and phosphate systems such as LiPON can be appropriately selected and used, but are not particularly limited thereto.

[0096]

[0097] In addition, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery, does not cause chemical changes in the battery, and has excellent electrical conductivity. Representative examples thereof include graphite or conductive carbon, and examples thereof include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black, and summer black; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers such as carbon fiber and metal fiber; fluorinated carbon; metal powder such as aluminum powder and nickel powder; conductive whiskey such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives; which may be used alone or in combination of two or more thereof, but are not necessarily limited thereto. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0098] The conductive material may typically be included in an amount of 1 wt% to 5 wt% based on the total weight of the positive electrode active material layer, and specifically, the content of the conductive material may be 1 wt% or more, 1.5 wt% or more, or 2 wt% or more, and 4 wt% or less, 4.5 wt% or less, or 5 wt% or less. If the content of the conductive material is too low, such as less than 1 wt%, it may be difficult to expect an effect of improving electrical conductivity or the electrochemical characteristics of the battery may deteriorate, and if it exceeds 5 wt%, the amount of positive electrode active material may be relatively small, which may lower the capacity and energy density. The method of including the conductive material in the positive electrode is not particularly limited, and conventional methods known in the art, such as mixing or coating with the positive electrode active material, may be used.

[0099]

[0100] In addition, the binder is a component that assists in the bonding of the positive electrode active material and the conductive material and the bonding to the current collector, and includes styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenol resin, epoxy resin, carboxymethylcellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate It may include at least one selected from the group consisting of butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0101] In addition, the binder may be included in an amount of 0.5 wt% to 4 wt% based on the total weight of the positive electrode active material layer, and specifically, the content of the binder may be 0.5 wt% or more, 1 wt% or more, or 1.5 wt% or more, and 3 wt% or less, 3.5 wt% or less, or 4 wt% or less. If the content of the binder is less than 0.5 wt%, the adhesive strength between the positive electrode active material and the positive electrode current collector may be reduced, and if it exceeds 4 wt%, the adhesive strength may be improved, but the content of the positive electrode active material may be reduced, which may lower the battery capacity.

[0102]

[0103] In one embodiment of the present invention, the solid electrolyte layer may be 1.0 to 1.8 times wider than the area of ​​the positive electrode active material layer. Here, the area of ​​the solid electrolyte layer and the area of ​​the positive electrode active material layer refer to the areas when the solid electrolyte layer and the positive electrode active material layer are viewed from above.

[0104]

[0105] Since the solid electrolyte layer is formed to surround one side of the positive electrode active material layer and a side adjacent to the one side, the area of ​​the solid electrolyte layer is larger than the area of ​​the positive electrode active material layer. If the area of ​​the solid electrolyte layer is less than 1.0 times the area of ​​the positive electrode active material layer, a step may occur between the solid electrolyte layer and the positive electrode current collector or the negative electrode layer, and if it exceeds 1.8 times, the lithium ion movement path may become longer or the production cost may increase. Specifically, the area of ​​the solid electrolyte layer may be 1.0 times or more, 1.1 times or more, 1.2 times or more, 1.3 times or more, or 1.4 times or less, and 1.8 times or less, 1.7 times or less, 1.6 times or less, or 1.5 times or less, compared to the area of ​​the positive electrode active material layer.

[0106] Additionally, the solid electrolyte layer may include a sulfide-based solid electrolyte, a halide-based solid electrolyte, or an oxide-based solid electrolyte. In terms of lithium ion conductivity, the solid electrolyte layer may include a sulfide-based solid electrolyte.

[0107] The above sulfide-based solid electrolyte may include a compound represented by the following chemical formula 1 or a mixture thereof:

[0108] <Chemical Formula 1>

[0109] Li a M b S c X d

[0110] In the above chemical formula 1, M is selected from P, Sn, Sb, As, and Ge;

[0111] The above X is selected from Cl, Br and I,

[0112] 5 ≤ a ≤ 7.5, 0.5 < b ≤ 1.5, 4 < c ≤ 6, and 0.5 < d ≤ 2.

[0113] The above halide-based solid electrolyte may be represented by the following chemical formula 2:

[0114] <Chemical Formula 2>

[0115] Li 6-3a M a Br b Cl c

[0116] In the above chemical formula 2, M is a metal other than Li, and a is 0 <a<2 이고, b는 0≤b≤6 이고, c는 0≤c≤6 이며, b+c=6 이다.

[0117] For example, the halide solid electrolyte may include at least one selected from the group consisting of Li3YBr6, Li3YCl6, and Li3YBr2Cl4.

[0118] The above oxide-based solid electrolyte is Li 3x La 2 / 3-xLLT system with perovskite structure such as TiO3, Li 14 LISICON, Li such as Zn(GeO4)4 1.3 Al 0.3 Ti 1.7 LATP series such as (PO4)3, (Li 1+x Ge 2-x Al x LAGP systems such as (PO4)3) and phosphate systems such as LiPON can be appropriately selected and used, but are not particularly limited thereto.

[0119]

[0120] In one embodiment of the present invention, the negative electrode layer may include a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector, and the negative electrode active material layer may be laminated so as to be in contact with the solid electrolyte layer. Alternatively, the negative electrode layer may include a negative electrode current collector; and a non-cathode coating layer formed on the negative electrode current collector, and the non-cathode coating layer may be laminated so as to be in contact with the solid electrolyte layer.

[0121]

[0122] The above negative electrode active material layer includes a negative electrode active material, a binder, and a conductive material.

[0123] The above negative active material is lithium (Li + ) can be reversibly intercalated or deintercalated, a material that can react with lithium ions to form a reversibly lithium-containing compound, or a lithium metal or a lithium alloy.

[0124] The above lithium ion (Li + ) can be reversibly inserted or de-inserted, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may include graphite. The lithium ion (Li +) can be, for example, tin oxide, titanium nitrate or silicon. The lithium alloy can be, for example, an alloy of lithium (Li) and a metal selected from the group consisting of indium (In), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al) and tin (Sn).

[0125] Preferably, the negative electrode active material may be lithium metal or a lithium-indium alloy (Li-In), and specifically, may be in the form of a lithium metal or lithium and a thin film or a lithium-indium alloy thin film or powder.

[0126] The negative electrode active material may be included in an amount of 40 to 80 wt% based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40 wt% or more or 50 wt% or more, and 70 wt% or less or 80 wt% or less. If the content of the negative electrode active material is less than 40 wt%, the connectivity between the wet negative electrode active material layer and the dry negative electrode active material layer may be insufficient, and if it exceeds 80 wt%, the material transfer resistance may increase.

[0127] In addition, the binder is a component that assists in the bonding of the negative electrode active material and the conductive material and the bonding to the negative electrode current collector, and includes styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenol resin, epoxy resin, carboxymethylcellulose, hydroxypropyl cellulose, cellulose acetate, cellulose It may include at least one selected from the group consisting of acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0128] In addition, the binder may be included in an amount of 0.5 wt% to 4 wt% based on the total weight of the negative electrode active material layer, and specifically, the content of the binder may be 0.5 wt% or more, 1 wt% or more, or 1.5 wt% or more, and 3 wt% or less, 3.5 wt% or less, or 4 wt% or less. If the content of the binder is less than 0.5 wt%, the adhesive strength between the positive electrode active material and the negative electrode current collector may be reduced, and if it exceeds 4 wt%, the adhesive strength may be improved, but the content of the negative electrode active material may be reduced, which may lower the battery capacity.

[0129]

[0130] In addition, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery, does not cause chemical changes in the battery, and has excellent electronic conductivity. Representative examples thereof include graphite or conductive carbon, and examples thereof include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black, and summer black; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers such as carbon fiber and metal fiber; fluorinated carbon; metal powder such as aluminum powder and nickel powder; conductive whiskey such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives; which may be used alone or in combination of two or more thereof, but are not necessarily limited thereto. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0131] The conductive material may typically be included in an amount of 1 wt% to 5 wt% based on the total weight of the negative electrode active material layer, and specifically, the content of the conductive material may be 1 wt% or more, 1.5 wt% or more, or 2 wt% or more, and 4 wt% or less, 4.5 wt% or less, or 5 wt% or less. If the content of the conductive material is too low, less than 1 wt%, it may be difficult to expect the effect of improving electronic conductivity or the electrochemical characteristics of the battery may deteriorate, and if it exceeds 5 wt%, the amount of the negative electrode active material may be relatively small, which may lower the capacity and energy density. The method of including the conductive material in the negative electrode is not particularly limited, and conventional methods known in the art, such as mixing with the negative electrode active material or coating, may be used.

[0132] In addition, the negative electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery. For example, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. In addition, the negative electrode current collector, like the positive electrode current collector, may be made of various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc. having fine irregularities formed on the surface.

[0133] The method for manufacturing the above negative electrode is not particularly limited, and can be manufactured by forming a negative electrode active material layer on the negative electrode current collector using a method for forming a layer or film commonly used in the art. For example, methods such as compression, coating, and deposition can be used. In addition, a case in which a battery is assembled on the negative electrode current collector without a lithium thin film and then a metallic lithium thin film is formed on the metal plate through initial charging is also included in the negative electrode of the present invention.

[0134]

[0135] In addition, the non-cathode coating layer does not contain a negative electrode active material, and a negative electrode active material may be formed in the non-cathode coating layer by charging. For example, when the battery is charged, lithium ions may move from the positive electrode and lithium metal may be precipitated from the negative electrode. In other words, the non-cathode coating layer may be a film that induces lithium precipitation.

[0136] The above-mentioned cathode-free coating layer may include metal particles and carbon material particles, and specifically, may include a carbon material-metal composite.

[0137] The above carbon material particles may be, for example, amorphous carbon material particles. However, the carbon material particles are not limited to amorphous particles. Specific examples of the above amorphous carbon material include carbon black such as acetylene black, furnace black, and Ketjen black, graphene, or combinations thereof.

[0138] In addition, the metal particles may be particles that form an alloy with lithium, and the metal particles may be at least one type of particle selected from silver (Ag), gold, platinum, palladium, silicon, aluminum, bismuth, tin, indium, and zinc. The non-cathode coating layer may be formed as a very thin film with a micro-thickness, and may be formed with a thickness of, for example, 10 μm or less.

[0139] Preferably, the non-cathode coating layer may include an Ag-C composite as a carbon material-metal composite, and upon first charging, lithium may be precipitated between the negative electrode current collector and the coating layer including the Ag-C composite.

[0140]

[0141] In one embodiment of the present invention, the all-solid-state battery may be a pouch-type all-solid-state battery.

[0142]

[0143] Manufacturing method of all-solid-state battery

[0144] The present invention also relates to a method for manufacturing an all-solid-state battery.

[0145] The method for manufacturing an all-solid-state battery according to the present invention comprises the following steps (S1) to (S3):

[0146] (S1) A step of arranging a plurality of unit cell forming structures at regular intervals on one side of a positive electrode current collector sheet;

[0147] (S2) A step of pressing a positive electrode current collector sheet on which a structure for forming the above unit cell is arranged;

[0148] (S3) a step of forming an insulating layer alternately between the plurality of unit cell forming structures; and

[0149] (S4) Including a step of folding from the end of the above positive electrode current collector sheet,

[0150] The above unit cell forming structure includes a positive electrode active material layer, a solid electrolyte layer, and a negative electrode layer,

[0151] During the above folding, (i) a first folding step in which the negative electrode layers of adjacent unit cells are stacked, and (ii) a second folding step in which the positive electrode current collectors of adjacent unit cells are stacked are alternately performed.

[0152]

[0153] The method for manufacturing an all-solid-state battery according to the present invention will be described in more detail step by step with reference to the drawings below.

[0154] Figure 4 is a process diagram showing a method for manufacturing an all-solid-state battery according to one embodiment of the present invention.

[0155]

[0156] In one embodiment of the present invention, in the step (S1), a plurality of unit cell forming structures (100a) may be arranged at regular intervals on one surface of the positive electrode current collector sheet (111a). The positive electrode current collector sheet (111a) refers to a positive electrode current collector having a size sufficient to allow a plurality of unit cell forming structures (100a) to be laminated at regular intervals, and may refer to a positive electrode current collector used before the folding process.

[0157]

[0158] The above unit cell forming structure (100a) means the unit cell (100) described above, excluding the positive electrode current collector (111). That is, the unit cell forming structure (100a) includes a positive electrode active material layer (112), a solid electrolyte layer (120), and a negative electrode layer (130), and the solid electrolyte layer (120) may be in a form that surrounds one side of the positive electrode active material layer (112) and four side surfaces adjacent to the one side.

[0159]

[0160] When the unit cell forming structure (100a) is arranged on one side of the positive electrode collector sheet (111a), the gap can be adjusted by considering the folding process described below. In the folding process, (i) a first folding step for stacking the negative electrode layers (130) of adjacent unit cells (100) and (ii) a second folding step for stacking the positive electrode collectors (111) of adjacent unit cells (100) can be alternately performed. When (i) the first folding step is performed, a first folding portion (F1) is formed, and since the first folding portion (F1) is formed on the side surface of the adjacent unit cell (100), a gap between the unit cell forming structures (100a) corresponding to the length of the side surface of the adjacent unit cell (100) may be required. When the above (ii) second folding step is performed, a second folding portion (F2) is formed, and since adjacent positive electrode collectors (111) are laminated in the second folding portion (F2), a gap may not be necessary when arranging the unit cell forming structure (100a) on the positive electrode collector sheet (111a). However, if a buffer layer (300) is formed as described below, the unit cell forming structure (100a) may be further spaced apart from each other by the thickness of the buffer layer (300) on the positive electrode collector sheet (111a) in order to perform the first folding step and the second folding step. Specifically, when the buffer layer (300) is formed, the gap between the unit cell forming structures (100a) in the (i) first folding step may be the sum of the thickness of two adjacent unit cell forming structures (100a) and the thickness of the buffer layer (300), and the gap between the unit cell forming structures (100a) in the (ii) second folding step may be the thickness of the buffer layer (300), which is 50 ㎛ to 15 mm. In addition, the folding directions of the first folding step and the second folding step may be opposite to each other.

[0161]

[0162] In one embodiment of the present invention, in the step (S2), the positive electrode current collector sheet (111a) on which the unit cell forming structure (100a) is arranged can be pressed.

[0163] When pressurizing, a pressurizing roll (RL) can be used. When the unit cell forming structure (100a) is passed through the pressurizing roll (RL) and pressurized, the adhesive strength between the positive electrode current collector sheet (111a) and the unit cell forming structure (100a), and the adhesive strength between the positive electrode active material layer (112), the solid electrolyte layer (120), and the negative electrode layer (130) included in the unit cell forming structure (100a) can be improved.

[0164] The pressure during the pressurization is not particularly limited as long as it improves the adhesive strength between the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer without deforming their shapes. Before and after the pressurization, if the thickness change amount of the unit cell forming structure (100a) is 11 to 17%, the adhesive strength as described above can be improved. If the thickness change amount is less than 11%, the adhesive strength is insufficient, and if it exceeds 17%, the adhesive strength is excessive, which may cause structural deformation. Specifically, the thickness change may be 11% or more, 11.1% or more, 11.2% or more, 11.3% or more, 11.4% or more, 11.5% or more, 11.6% or more, 11.7% or more, 11.8% or more, 11.9% or more, 12% or more, 12.5% ​​or more, 13% or more, 13.5% or more, 14% or more, 14.5% or more, or 15% or more, and may be 17% or less, 16.9% or less, 16.8% or less, 16.7% or less, 16.6% or less, 16.5% or less, 16.4% or less, 16.3% or less, 16.2% or less, 16.1% or less, or 16% or less. In this case, the thickness change may mean a thickness reduction amount due to pressurization.

[0165]

[0166] In one embodiment of the present invention, in the step (S3), insulating layers may be formed alternately between the plurality of unit cell forming structures. That is, rather than forming insulating layers between all of the plurality of unit cell forming structures, insulating layers are formed alternately between the plurality of unit cell forming structures.

[0167] The above insulating layer can be formed by coating an insulating layer-forming slurry between the unit cell-forming structures. The insulating layer-forming slurry can be prepared by mixing a thermoplastic polymer with a solvent. The solvent may be at least one selected from the group consisting of tetrahydrofuran (THF), dimethylacetamide (DMAC), dimethylformamide (DMF), dimethylsulfoxide (DMSO), toluene, N-methyl-2-pyrrolidone (NMP), tetramethyl urea, triethyl phosphate, and acetone, but is not limited thereto as long as it is a solvent for forming a coating slurry. In addition, the concentration of the slurry can be appropriately adjusted so that the coating process can be smoothly performed. For example, the concentration of the slurry may be 20% to 40%, specifically 20% or more, 21% or more, 22% or more, 23% or more, 24% or more, or 25% or more, and 40% or less, 39% or less, 38% or less, 37% or less, 36% or less, or 35%.

[0168] In addition, the coating method for forming the insulating layer is not particularly limited as long as it is a method capable of forming a coating layer. For example, the coating method may be spray coating, spin coating, die coating, roll coating, slot-die coating, bar coating, gravure coating, comma coating, curtain coating, or micro-gravure coating.

[0169]

[0170] In one embodiment of the present invention, in the step (S4), after the pressurization, the positive electrode current collector sheet (111a) can be folded from the end.

[0171] In the above folding, (i) a first folding step for stacking the negative electrode layers (130) of adjacent unit cells (100), and (ii) a second folding step for stacking the positive electrode current collectors (111) of adjacent unit cells (100) may be alternately performed. As long as the first folding step and the second folding step are alternately performed, there is no particular limitation on which step is performed first. For example, the first folding step may be performed first, or the second folding step may be performed first.

[0172]

[0173] In one embodiment of the present invention, a buffer layer (300) can be additionally formed between unit cells (100) in the folding step.

[0174] After positioning and inserting the buffer layer (300) on the negative electrode layer (130) or positive electrode current collector (111) adjacent to the unit cells (100) and stacking them, the first folding step and / or the second folding step can be performed. The material and morphological characteristics of the buffer layer (300) are as described above. The buffer layer (300) may be in the form of a layer.

[0175]

[0176] In one embodiment of the present invention, the structure for forming the unit cell can be manufactured by the following steps (A1) to (A4):

[0177] (A1) A step of forming a positive electrode active material layer of a certain area on a substrate;

[0178] (A2) A step of forming a solid electrolyte layer on the positive electrode active material layer so as to surround one side of the positive electrode active material layer and side surfaces adjacent to the one side;

[0179] (A3) a step of forming a cathode layer on the solid electrolyte layer, the area of ​​which is the same as that of the solid electrolyte layer; and

[0180] (A4) Step of transforming the above description.

[0181]

[0182] Hereinafter, the method for manufacturing a structure for forming a unit cell according to the present invention will be described in more detail step by step.

[0183]

[0184] In one embodiment of the present invention, in the step (A1), a positive electrode active material layer of a certain area can be formed on the substrate.

[0185] The area of ​​the substrate may be larger than the area of ​​the positive electrode active material layer. The area of ​​the substrate may be 1.0 to 1.8 times larger than the area of ​​the positive electrode active material layer. The area of ​​the substrate may be equal to or larger than the area of ​​the solid electrolyte layer.

[0186] In addition, the substrate is not particularly limited as long as it is a releasable film. For example, the substrate may be selected from the group consisting of polyethylene terephthalate (PET), polyimide (PI), poly(methylmethacrylate) (PMMA), polypropylene, polyethylene, and polycarbonate.

[0187]

[0188] The above positive electrode active material layer can be manufactured by applying and drying a composition for forming a positive electrode active material layer prepared by mixing a positive electrode active material, a solid electrolyte, a conductive agent, and a binder in an organic solvent phase onto a substrate, and optionally, compression molding the composition onto the substrate to improve electrode density. At this time, it is preferable to use an organic solvent that can uniformly disperse the positive electrode active material, the solid electrolyte, the binder, and the conductive agent, and that easily evaporates. Specific examples thereof include acetonitrile, methanol, ethanol, xylene, toluene, hexane, tetrahydrofuran, water, and isopropyl alcohol.

[0189]

[0190] In one embodiment of the present invention, in the step (A2), a solid electrolyte layer may be formed on the positive electrode active material layer so as to surround one side of the positive electrode active material layer and side surfaces adjacent to the one side. In the positive electrode active material layer, one side in contact with the positive electrode current collector may be referred to as the first side, the other side may be referred to as the second side, and the four side surfaces adjacent to the first and second sides may be referred to as the first side, the second side, the third side, and the fourth side.

[0191] The solid electrolyte layer is formed on the positive electrode active material layer, and is formed so as to surround the second side and the first to fourth side surfaces of the positive electrode active material. In addition, since the area of ​​the positive electrode current collector is larger than the area of ​​the positive electrode active material layer, the solid electrolyte layer is formed in contact with the substrate even on which the positive electrode active material layer is not in contact.

[0192] The above solid electrolyte layer can be manufactured by applying a slurry obtained by mixing a solid electrolyte and a binder in a solvent onto the positive electrode active material layer and then drying it.

[0193] The above solid electrolyte may include at least one selected from the group consisting of a sulfide-based solid electrolyte, a halide-based solid electrolyte, and an oxide-based solid electrolyte, as described above.

[0194] In addition, the binder may include at least one selected from the group consisting of acrylic copolymers, acrylic block copolymers, acrylic monomers, random copolymers of oligomers, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymers, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymers, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, and ethylene / propylene copolymers.

[0195] In addition, the binder may be included in an amount of 5 to 15 parts by weight based on 100 parts by weight of the solid electrolyte. Specifically, the content of the binder may be 5 parts by weight or more, 7 parts by weight or more, or 9 parts by weight or more, or 11 parts by weight or less, 13 parts by weight or less, or 15 parts by weight or less. If the content of the binder is less than 5 parts by weight, it may be difficult to form a solid electrolyte layer, and if it exceeds 15 parts by weight, ionic conductivity may decrease.

[0196] In addition, the solvent is not particularly limited as long as it is a solvent that can dissolve and / or disperse the solid electrolyte and / or binder to form a slurry. For example, the solvent may be at least one selected from the group consisting of dimethylsulfoxide (DMSO), isopropyl alcohol, ethyl butyrate, heptyl butyrate, hexyl butyrate, butyl butyrate, isopropyl butyrate, isobutyl isobutyrate, N-methylpyrrolidone (NMP), acetone, xylene, dimethylformamide (N,N-Dimethylmethanamide (DMF), benzene, tetrahydrofuran (THF), and water. The amount of the above solvent can be adjusted by considering the thickness of the coating layer applied, the properties of the solid electrolyte to be manufactured, etc.

[0197] The above coating method may be bar coating, roll coating, spin coating, slit coating, die coating, blade coating, comma coating, slot die coating, lip coating, or solution casting, but is not limited thereto as long as it is a method capable of forming a layer by coating.

[0198] The drying method described above is not particularly limited as long as it can form a film (layer) by evaporating the solvent after application. For example, the drying may be performed at a temperature of 300°C or lower. Specifically, the drying temperature may be 300°C or lower, 200°C or lower, 150°C or lower, or 100°C or lower.

[0199]

[0200] In one embodiment of the present invention, in the step (A3), a cathode layer having the same area as the solid electrolyte layer can be formed by laminating it on the solid electrolyte layer.

[0201]

[0202] In one embodiment of the present invention, in the step (A4), after the substrate is removed by molding, a structure for forming a unit cell including the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer can be obtained.

[0203]

[0204] According to a preferred embodiment of the present invention, FIGS. 5a to 5d are schematic diagrams for a manufacturing process of a structure for forming a unit cell (5a: arrangement of an anode, 5b: manufacturing a solid electrolyte layer, 5c: schematic diagram of the top surface and longitudinal cross-section of the manufactured solid electrolyte layer, 5d: cutting of a laminate including an anode layer and a solid electrolyte layer). According to the manufacturing process, a structure for forming a unit cell can be manufactured as follows.

[0205] A plurality of positive electrode active material layers (112) are formed by pressing on a PET release film (RF) (Fig. 5a). Then, a slurry (S) for forming a solid electrolyte is coated with a doctor blade (DB) (Fig. 5b) and dried to form a solid electrolyte layer (120) (Fig. 5c). The laminate of the positive electrode active material layer and the solid electrolyte layer is cut into units of one positive electrode active material layer (Fig. 5d). The area of ​​the solid electrolyte layer is formed to be larger than the area of ​​the positive electrode active material layer. The slurry for forming the solid electrolyte is prepared by mixing Li6PS5Cl, which is a sulfide-based solid electrolyte particle having an argyrodite structure, a rubber-based binder, and a butyrate-based solvent. At this time, the area of ​​the positive electrode is A 2 ㎟, the area of ​​the solid electrolyte layer is B 2 ㎟, the spacing between the anodes was set to C ㎜ when arranging the anodes, and the process was carried out so that C < A < B and C = (BA).

[0206] Thereafter, a cathode layer is laminated on the solid electrolyte layer, and a structure for forming a unit cell is manufactured by pressurizing at a pressure of 400 MPa. In the structure for forming a unit cell, the combined area of ​​the cathode active material layer and the solid electrolyte layer surrounding it, the area of ​​the solid electrolyte layer, and the area of ​​the cathode layer are the same.

[0207]

[0208] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0209]

[0210] [Explanation of symbols]

[0211] 1: All-solid-state battery

[0212] 100: Unit cell

[0213] 100a: Structure for forming unit cells

[0214] 110: Bipolar layer

[0215] 111: positive electrode current collector, 112: positive electrode active material layer

[0216] 111a: Positive current collector sheet

[0217] 120: Solid electrolyte layer

[0218] 130: Cathode layer

[0219] 131: Negative current collector, 132: Negative active material layer

[0220] 300: Buffer layer

[0221] 400: Insulating layer

[0222] F1: First folding section

[0223] F2: Second folding section

[0224] C: Crack, D: Collapse

[0225] RF: Release film, S: Slurry, DB: Doctor Blade

[0226] RL: Pressurized Roll

Claims

1. An all-solid-state battery formed by stacking multiple unit cells, The unit cell includes a positive electrode layer including a positive electrode active material layer in contact with a certain area of ​​one side of a positive electrode current collector; a solid electrolyte layer having a shape surrounding one side of the positive electrode active material layer and side surfaces adjacent to the one side and formed to be in contact with the positive electrode current collector; and a negative electrode layer positioned on the solid electrolyte layer and having an area equal to that of the solid electrolyte layer. The above multiple unit cells are stacked so that the interfaces adjacent to each other in the positive electrode current collectors and the interfaces adjacent to each other in the negative electrode layers appear alternately, A first folding part is formed on a first side perpendicular to the direction in which the unit cells are stacked, and the first folding part includes a positive electrode current collector and an insulating layer formed on one side of the positive electrode current collector. An all-solid-state battery, wherein the first folding portion is continuously formed on the first side.

2. In paragraph 1, An all-solid-state battery further comprising a buffer layer formed between the plurality of unit cells.

3. In paragraph 1, An all-solid-state battery, wherein the space between the plurality of unit cells is between the negative current collectors or the positive current collectors included in the plurality of unit cells.

4. In paragraph 2, An all-solid-state battery, wherein the buffer layer comprises at least one selected from the group consisting of silicone, gel polymer, polytetrafluoroethylene (PTFE), and polyurethane foam.

5. In paragraph 2, An all-solid-state battery, wherein the first folding portion formed on the first side perpendicular to the direction in which the unit cells are stacked is formed discontinuously based on the buffer layer formed between the positive electrode current collectors included in the plurality of unit cells.

6. In paragraph 1, The negative electrode layer includes a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector, An all-solid-state battery, wherein the negative active material layer is laminated so as to be in contact with the solid electrolyte layer.

7. In paragraph 1, The cathode layer includes a cathode current collector; and a non-cathode coating layer formed on the cathode current collector, An all-solid-state battery, wherein the non-cathode coating layer is laminated so as to be in contact with the solid electrolyte layer.

8. In paragraph 1, The above all-solid-state battery is a pouch-type all-solid-state battery.

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