All-solid-state battery and method for manufacturing same

Abstract

The present invention relates to an all-solid-state battery and a method for manufacturing same. More specifically, the all-solid-state battery according to the present invention ensures that the cross-sectional shapes and areas of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are the same in a unit cell in which the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are stacked, and thus the all-solid-state battery can have improved structural stability.

Description

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

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0157932, dated November 15, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to an all-solid-state battery and a method for manufacturing the same.

[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 cross-sections of an all-solid-state battery according to the prior art (1a: cross-section of a unit cell, 1b: cross-section of a stack cell, 1c: 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 in an all-solid-state battery including a unit cell or a stack cell in which multiple unit cells are stacked, a unit cell including a positive electrode layer, a solid electrolyte layer, and a negative electrode layer is formed, and the shape and area of ​​the cross-section of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are designed to be identical, thereby ensuring the structural stability of the all-solid-state battery.

[0020] Accordingly, the purpose of the present invention is to provide an all-solid-state battery with secured structural stability and a method for manufacturing the same.

[0021] To achieve the above purpose, the present invention provides an all-solid-state battery including a unit cell,

[0022] The above unit cell is,

[0023] positive current collector;

[0024] A positive electrode active material layer in contact with a certain area of ​​one surface of the positive electrode current collector;

[0025] 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

[0026] An all-solid-state battery is provided, which includes a cathode layer positioned on the solid electrolyte layer and having an area equal to that of the solid electrolyte layer.

[0027] In one embodiment of the present invention, an all-solid-state battery is provided, wherein the area of ​​the solid electrolyte layer is 1.3 to 1.8 times wider than the area of ​​the positive electrode active material layer.

[0028] In one embodiment of the present invention, an all-solid-state battery is provided, wherein the negative electrode layer includes 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 is laminated so as to be in contact with the solid electrolyte layer.

[0029] In one embodiment of the present invention, an all-solid-state battery is provided, wherein the negative electrode layer includes a negative electrode current collector; and a non-cathode coating layer formed on the negative electrode current collector, and the non-cathode coating layer is laminated so as to be in contact with the solid electrolyte layer.

[0030] In one embodiment of the present invention, an all-solid-state battery is provided, wherein two or more unit cells are stacked.

[0031] In one embodiment of the present invention, an all-solid-state battery is provided, wherein the all-solid-state battery is in a pouch shape.

[0032]

[0033] The present invention also comprises the steps of (S1) forming a positive electrode active material layer of a certain area on a positive electrode current collector;

[0034] (S2) 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;

[0035] (S3) 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

[0036] (S4) A method for manufacturing an all-solid-state battery is provided, including a unit cell manufacturing process including a step of bonding the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer by applying pressure in the direction in which they are laminated.

[0037] In one embodiment of the present invention, a method for manufacturing an all-solid-state battery is provided, wherein the pressure is 300 to 700 MPa.

[0038] 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.

[0039] In addition, in order to improve energy density, even when two or more of the above unit cells are stacked to form a stack cell, structural stability can be exhibited, thereby exhibiting excellent life characteristics.

[0040] Figures 1a to 1c are schematic diagrams showing cross-sections of an all-solid-state battery according to the prior art (1a: cross-section of a unit cell, 1b: cross-section of a stack cell, 1c: cross-section of a stack including a cathode layer and a solid electrolyte layer).

[0041] Figure 2 is the structure of an all-solid-state battery disclosed in Korean Patent Publication No. 2022-0080930.

[0042] Figures 3a to 3c are schematic diagrams showing cross-sections of an all-solid-state battery according to the present invention (3a: cross-section of a unit cell, 3b: cross-section of a stack cell, 3c: cross-section of a stack including a cathode layer and a solid electrolyte layer).

[0043] FIGS. 4a to 4d are schematic diagrams of a unit cell manufacturing process according to a preferred embodiment of the present invention (4a: anode arrangement, 4b: solid electrolyte layer manufacturing, 4c: top surface and longitudinal cross-sectional schematic diagram of the manufactured solid electrolyte layer, 4d: cutting of a laminate including anode layer and solid electrolyte layer).

[0044] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0045] 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.

[0046]

[0047] All-solid-state batteries

[0048] The present invention relates to an all-solid-state battery.

[0049] The all-solid-state battery according to the present invention includes a unit cell,

[0050] The above unit cell is

[0051] positive current collector,

[0052] A positive electrode active material layer in contact with a certain area of ​​one surface of the positive electrode current collector;

[0053] 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

[0054] A unit cell including a cathode layer positioned on the solid electrolyte layer and having an area equal to that of the solid electrolyte layer.

[0055] Since the all-solid-state battery according to the present invention does not contain any heterogeneous materials other than the positive electrode layer, the solid electrolyte layer, and the negative electrode layer, problems such as structural instability or deterioration of battery performance due to the addition of heterogeneous materials can be prevented.

[0056] Accordingly, the unit cell of the above all-solid-state battery may be composed of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer.

[0057]

[0058] FIGS. 3a to 3c are schematic diagrams showing cross-sections of unit cells included in an all-solid-state battery according to one embodiment of the present invention (3a: cross-section of unit cell, 3b: cross-section of stack cell, 3c: cross-section of stack including a cathode layer and a solid electrolyte layer).

[0059] Referring to FIGS. 3a to 3c, a unit cell (100) included in an all-solid-state battery has a structure in which a positive electrode current collector (111), a positive electrode active material layer (112), a solid electrolyte layer (120), and a negative electrode layer (130) are sequentially laminated.

[0060] 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), in addition to the one side in contact with the positive electrode current collector (111), the other side and four side surfaces adjacent to the other side are surrounded by a solid electrolyte layer (120). At this time, in the positive electrode active material layer (112), the one side in contact with the positive electrode current collector (111) 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 side and the second side may be referred to as the first side, the second side, the third side, and the fourth side surfaces.

[0061] The unit cell (100) or the stack cell (200) in which they are stacked 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) plus the cross-section of the solid electrolyte layer (120) may be the same as the area and shape of the positive electrode current collector (111) (FIGS. 3A and 3B).

[0062] 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).

[0063]

[0064] 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.

[0065] 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.

[0066] 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.

[0067] In addition, the positive electrode current collector may have a finely irregular 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.

[0068]

[0069] 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.

[0070] The above positive electrode active material layer includes a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0071] 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 y Lithium 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.

[0072] In addition, the positive electrode active material may be included in an amount of 60 to 80 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 68 wt% or more, and may be 72 wt% or less, 75 wt% or less, or 80 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 80 wt%, mass transfer resistance may increase.

[0073] 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.

[0074] The above sulfide-based solid electrolyte may include a compound represented by the following chemical formula 1 or a mixture thereof:

[0075] <Chemical Formula 1>

[0076] Li a M b S c X d

[0077] In the above chemical formula 1, M is selected from P, Sn, Sb, As, and Ge;

[0078] wherein X is selected from Cl, Br and I,

[0079] 5 ≤ a ≤ 7.5, 0.5 < b ≤ 1.5, 4 < c ≤ 6, and 0.5 < d ≤ 2.

[0080] The above halide-based solid electrolyte may be represented by the following chemical formula 2:

[0081] <Chemical Formula 2>

[0082] Li 6-3a M a Br b Cl c

[0083] 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.

[0084] For example, the halide solid electrolyte may include at least one selected from the group consisting of Li3YBr6, Li3YCl6, and Li3YBr2Cl4.

[0085] 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.

[0086]

[0087] 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).

[0088] 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.

[0089]

[0090] 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).

[0091] 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.

[0092]

[0093] In one embodiment of the present invention, the solid electrolyte layer may be 1.3 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.

[0094] 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 1.3 times the area of ​​the positive electrode active material, a step may occur between the solid electrolyte layer and the positive electrode current collector or negative electrode layer, and if it exceeds 1.8 times, the lithium ion movement path may become longer or the production cost may increase.

[0095] 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.

[0096] The above sulfide-based solid electrolyte may include a compound represented by the following chemical formula 1 or a mixture thereof:

[0097] <Chemical Formula 1>

[0098] Li a M b S c X d

[0099] In the above chemical formula 1, M is selected from P, Sn, Sb, As, and Ge;

[0100] The above X is selected from Cl, Br and I,

[0101] 5 ≤ a ≤ 7.5, 0.5 < b ≤ 1.5, 4 < c ≤ 6, and 0.5 < d ≤ 2.

[0102] The above halide-based solid electrolyte may be represented by the following chemical formula 2:

[0103] <Chemical Formula 2>

[0104] Li 6-3a M a Br b Cl c

[0105] 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.

[0106] For example, the halide solid electrolyte may include at least one selected from the group consisting of Li3YBr6, Li3YCl6, and Li3YBr2Cl4.

[0107] 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.

[0108]

[0109] 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, and the negative electrode active material layer may be laminated so as to be in contact with the solid electrolyte layer.

[0110] Alternatively, the cathode layer may include a cathode current collector; and a non-cathode coating layer formed on the cathode current collector, and the non-cathode coating layer may be laminated so as to be in contact with the solid electrolyte layer.

[0111]

[0112] The above negative electrode active material layer includes a negative electrode active material, a binder, and a conductive material.

[0113] 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.

[0114] The above lithium ion (Li + ) can be reversibly inserted or de-inserted, for example, crystalline carbon, amorphous carbon, or a mixture thereof. 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).

[0115] 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.

[0116] 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.

[0117] 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).

[0118] 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.

[0119]

[0120] 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).

[0121] 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.

[0122] 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.

[0123] 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.

[0124]

[0125] 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.

[0126] The above-mentioned cathode-free coating layer may include metal particles and carbon material particles, and specifically, may include a carbon material-metal composite.

[0127] 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.

[0128] 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.

[0129] 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.

[0130]

[0131] In one embodiment of the present invention, two or more of the unit cells may be stacked to form a stack cell.

[0132] Since the above unit cell has a rectangular parallelepiped shape, even if two or more of the above unit cells are stacked, they have a rectangular parallelepiped shape, and thus the stack cell can also have structural stability.

[0133]

[0134] In one embodiment of the present invention, the all-solid-state battery may be a pouch-type all-solid-state battery.

[0135]

[0136] Method for manufacturing an all-solid-state battery

[0137] The present invention also relates to a method for manufacturing an all-solid-state battery.

[0138] The method for manufacturing an all-solid-state battery according to the present invention includes a unit cell manufacturing process including the following steps (S1) to (S4):

[0139] (S1) A step of forming a positive electrode active material layer of a certain area on a positive electrode current collector;

[0140] (S2) 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;

[0141] (S3) 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

[0142] (S4) A step of bonding the positive electrode current collector, positive electrode active material layer, solid electrolyte layer, and negative electrode layer by applying pressure in the stacked direction.

[0143]

[0144] Below, the method for manufacturing an all-solid-state battery according to the present invention is described in more detail step by step.

[0145] In one embodiment of the invention, in the step (S1), a positive electrode active material layer of a certain area can be formed on the positive electrode current collector.

[0146] The area of ​​the positive electrode current collector may be larger than the area of ​​the positive electrode active material layer. The area of ​​the positive electrode current collector may be 1.3 to 1.8 times larger than the area of ​​the positive electrode active material layer. The area of ​​the positive electrode current collector may be equal to the area of ​​the solid electrolyte layer, which may be advantageous for manufacturing a rectangular parallelepiped unit cell.

[0147] 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 positive electrode current collector, and optionally, compression molding the composition onto the positive electrode current collector 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.

[0148]

[0149] In one embodiment of the present invention, in the step (S2), a solid electrolyte layer may be formed on the positive electrode active material layer 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 side and the second side may be referred to as the first side, the second side, the third side, and the fourth side.

[0150] The above 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 positive electrode current collector even on the positive electrode current collector to which the positive electrode active material layer is not in contact.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158]

[0159] In one embodiment of the present invention, in the step (S3), a cathode layer having the same area as the solid electrolyte layer can be formed by laminating it on the solid electrolyte layer.

[0160]

[0161] In one embodiment of the present invention, in the step (S4), the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer can be bonded by applying pressure in the direction in which they are laminated.

[0162] The above pressure may be 300 to 700 MPa, specifically 300 MPa or more, 350 MPa or more, or 400 MPa or more, 500 MPa or less, 550 MPa or less, 600 MPa or less, 650 MPa or less, or 700 MPa. If the above pressure is less than 300 MPa, the internal adhesive strength of the all-solid-state battery may not be good, and if it exceeds 700 MPa, cracks may occur in the positive electrode and electrolyte in the case of misalignment.

[0163]

[0164] According to a preferred embodiment of the present invention, FIGS. 4a to 4d are schematic diagrams for a unit cell manufacturing process (4a: anode arrangement, 4b: solid electrolyte layer manufacturing, 4c: top surface and longitudinal cross-sectional schematic diagram of the manufactured solid electrolyte layer, 4d: cutting of a laminate including the anode layer and the solid electrolyte layer). According to the above manufacturing process, a unit cell can be manufactured as follows.

[0165] A plurality of positive electrodes (110) are placed on a PET release film (RF) (Fig. 4a). Thereafter, a slurry (S) for forming a solid electrolyte is coated with a doctor blade (DB) (Fig. 4b) and dried to form a solid electrolyte layer (120) (Fig. 4c). The laminate of the positive electrode layer and the solid electrolyte layer is cut into units of one positive electrode layer (Fig. 4d). The area of ​​the solid electrolyte layer is formed to be larger than the area of ​​the positive electrode active material layer included in the positive electrode 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).

[0166] Thereafter, a cathode layer is laminated on the solid electrolyte layer, and a unit cell is manufactured by pressurizing at a pressure of 400 MPa. In the unit cell, the area of ​​the cathode current collector included in the cathode, 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.

[0167] A stack cell can be manufactured by stacking two of the above unit cells.

[0168]

[0169] 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.

[0170]

[0171] [Brief explanation of symbols]

[0172] 10: All-solid-state batteries

[0173] 100: Unit cell

[0174] 110: Bipolar layer

[0175] 111: positive electrode current collector, 112: positive electrode active material layer

[0176] 120: Solid electrolyte layer

[0177] 130: Cathode layer

[0178] 131: Negative current collector, 132: Negative active material layer

[0179] 200: Stack Cell

[0180] C: Crack, D: Collapse

[0181] RF: Release film, S: Slurry, DB: Doctor Blade

Claims

1. An all-solid-state battery comprising a unit cell, The above unit cell is, Bipolar collector; A layer of positive electrode active material in contact with a certain area of ​​one surface of the 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 An all-solid-state battery, comprising a cathode layer positioned on the solid electrolyte layer and having an area identical to that of the solid electrolyte layer.

2. In paragraph 1, An all-solid-state battery, wherein the area of ​​the solid electrolyte layer is 1.3 to 1.8 times larger than the area of ​​the positive electrode active material layer.

3. In paragraph 1, The above 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.

4. In paragraph 1, The above 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.

5. In paragraph 1, An all-solid-state battery in which two or more of the above unit cells are stacked.

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

7. (S1) A step of forming a positive electrode active material layer of a certain area on a positive electrode current collector; (S2) 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; (S3) 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 (S4) A method for manufacturing an all-solid-state battery, including a unit cell manufacturing process, comprising the step of bonding the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer by applying pressure in the direction in which they are laminated.

8. In paragraph 7, A method for manufacturing an all-solid-state battery, wherein the pressure is 300 to 700 MPa.

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