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

Abstract

The present invention relates to an all-solid-state battery and a manufacturing method thereof. More specifically, in the all-solid-state battery according to the present invention, a positive electrode active material layer is surrounded by a positive electrode current collector and a solid electrolyte layer, thereby preventing the positive electrode active material layer from elongating during a pressurizing step and ensuring the structural stability of the battery.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0166203, filed November 27, 2023, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an all-solid-state battery and a method for manufacturing the same. [Background technology]

[0003] Currently, various batteries that can overcome the limitations of lithium secondary batteries are being researched from the viewpoints of battery capacity, safety, output, size increase, and miniaturization.

[0004] Academia and industry are currently conducting ongoing research into metal-air batteries, which have a much larger theoretical capacity than lithium secondary batteries, all-solid-state batteries, which are safe and do not pose a risk of explosion, supercapacitors, NaS batteries or RFBs (redox flow batteries), which are large-scale batteries, and thin film batteries, which are ultra-small.

[0005] All-solid-state batteries are batteries in which the liquid electrolyte used in conventional lithium secondary batteries is replaced with a solid, and because they do not use flammable solvents, they are completely free of fires and explosions caused by the decomposition reactions of conventional electrolytes, thereby significantly improving stability. Furthermore, because lithium metal or lithium alloys can be used as the anode material, they have the advantage of dramatically improving the energy density relative to the mass and volume of the battery.

[0006] Generally, to manufacture an all-solid-state battery, a cell is manufactured through a stacking process in which a cathode, a solid electrolyte layer, and an anode are stacked in order, followed by a process of compressing an exterior body after the stack is arranged. The electrodes and solid electrolyte layers used in all-solid-state batteries are not all the same size. Therefore, the size difference between the electrodes or the solid electrolyte layer during the compression process can cause cracks at the edges. Furthermore, the cathode is characterized by its softness and high diffusivity due to the binders contained within it. Therefore, when pressing in one direction during the compression process, a portion of the cathode may be pushed to the unforced part, resulting in uneven stretching and reduced cell performance.

[0007] FIG. 1 is a schematic diagram showing a vertical cross section of an all-solid-state battery according to the prior art.

[0008] A unit cell (100) of a conventional 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 stacked. A stack cell (200) is formed by stacking a plurality of unit cells (100), and may be formed by stacking, for example, two or more unit cells (100). During the manufacture of the unit cells (100), the area of ​​the positive electrode layer (110) including the positive electrode current collector (111) and the positive electrode active material layer (112) is smaller than that of the adjacent solid electrolyte layer (120). Therefore, it is difficult to align the solid electrolyte layer (120) on the positive electrode layer (110), and misalignment may occur. Furthermore, after stacking the above-mentioned components, when pressure is applied, cracks (C) occur in the solid electrolyte layer (120) due to the difference in area between the adjacent positive electrode active material layer (112) and solid electrolyte layer (120), and if the stacked structure itself collapses (D), contact between the positive electrode layer and the negative electrode layer may occur.

[0009] Therefore, there is a need to develop technology that can ensure the structural stability of all-solid-state batteries so that cracks and expansion of the positive electrode can be prevented during the pressure process during cell assembly. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2022-186164 Summary of the Invention [Problem to be solved by the invention]

[0011] The present inventors have conducted extensive research to solve the above problems, and as a result have confirmed that in an all-solid-state battery including a unit cell or a stack cell in which a plurality of unit cells are stacked, the relatively small-sized positive electrode active material layer of a unit cell including a positive electrode current collector, a positive electrode current collector, a solid electrolyte layer, and a negative electrode layer is surrounded by the positive electrode current collector and the solid electrolyte layer, thereby eliminating variation in size of each component included in the unit cell and providing structural stability, thereby preventing problems such as cracking during the pressurizing process and elongation of the positive electrode.

[0012] Therefore, an object of the present invention is to provide an all-solid-state battery that ensures structural stability and a method for manufacturing the same. [Means for solving the problem]

[0013] In order to achieve the above object, the present invention provides an all-solid-state battery including a unit cell, the unit cell includes a positive electrode layer, a solid electrolyte layer formed on the positive electrode layer, and a negative electrode layer formed on the solid electrolyte layer, the positive electrode layer includes a positive electrode current collector having a receiving portion formed therein for receiving a portion of the positive electrode active material layer, and the positive electrode active material layer received in the receiving portion, The present invention provides an all-solid-state battery, wherein the solid electrolyte layer is formed in contact with the positive electrode current collector and the positive electrode active material layer.

[0014] In one embodiment of the present invention, there is provided an all-solid-state battery, wherein the height of the housing portion is smaller than the height of the positive electrode active material layer.

[0015] In one embodiment of the present invention, there is provided an all-solid-state battery in which a part of a side surface of the positive electrode active material layer is in contact with a positive electrode current collector and a part of the side surface is in contact with a solid electrolyte layer, and the part of the side surface of the positive electrode active material layer in contact with the positive electrode current collector is smaller than the part in contact with the solid electrolyte layer.

[0016] In one embodiment of the present invention, there is provided an all-solid-state battery, wherein the anode layer includes an anode current collector and an anode active material layer formed on the anode current collector, and the anode active material layer is laminated so as to be in contact with the solid electrolyte layer.

[0017] In one embodiment of the present invention, there is provided an all-solid-state battery, wherein the anode layer includes an anode current collector and a non-anode coating layer formed on the anode current collector, and the non-anode coating layer is laminated so as to be in contact with the solid electrolyte layer.

[0018] In one embodiment of the present invention, there is provided an all-solid-state battery, wherein two or more of the unit cells are stacked.

[0019] The present invention also provides (S1) forming a positive electrode active material layer on a positive electrode current collector having an accommodation portion formed thereon for accommodating a part of the positive electrode active material layer; (S2) forming a solid electrolyte layer on the positive electrode current collector and the positive electrode active material layer excluding the housing portion; (S3) forming a negative electrode layer on the solid electrolyte layer; (S4) applying pressure in the stacking direction of the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer to bond them together; The present invention provides a method for manufacturing an all-solid-state battery, including a manufacturing process for a unit cell including the steps of:

[0020] In one embodiment of the present invention, there is provided a method for producing an all-solid-state battery, wherein the pressure is 400 MPa to 700 MPa. [Effects of the Invention]

[0021] 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 relatively small positive electrode active material layer is surrounded by the positive electrode current collector and the solid electrolyte layer, so that the cross-sectional area of ​​the unit cell is constant and the structure is stable, and there is an effect of preventing the occurrence of cracks even in the pressurizing process.

[0022] In addition, a portion of the positive electrode active material layer is accommodated in and in contact with the positive electrode current collector, and another portion of the positive electrode active material layer is surrounded by the solid electrolyte layer, which has the effect of preventing the problem of the positive electrode active material layer being stretched during the pressurizing process. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram showing a vertical cross section of an all-solid-state battery according to the prior art. [Figure 2] FIG. 1 is a schematic diagram showing a vertical cross section of an all-solid-state battery according to an embodiment of the present invention. [Figure 3a] FIG. 1 is a schematic diagram showing the cross-sectional structure of all-solid-state batteries manufactured in Examples and Comparative Examples. [Figure 3b] FIG. 1 is a schematic diagram showing the cross-sectional structure of all-solid-state batteries manufactured in Examples and Comparative Examples. [Figure 3c] FIG. 1 is a schematic diagram showing the cross-sectional structure of all-solid-state batteries manufactured in Examples and Comparative Examples. [Figure 3d] FIG. 1 is a schematic diagram showing the cross-sectional structure of all-solid-state batteries manufactured in Examples and Comparative Examples. [Figure 4] 1 is a graph showing experimental results of life characteristics of all-solid-state batteries manufactured in Examples and Comparative Examples. [Figure 5a] 1 shows scanning electron microscope (SEM) photographs of cross sections of all-solid-state batteries manufactured in Examples and Comparative Examples. [Figure 5b] 1 shows scanning electron microscope (SEM) photographs of cross sections of all-solid-state batteries manufactured in Examples and Comparative Examples. [Figure 5c]1 shows scanning electron microscope (SEM) photographs of cross sections of all-solid-state batteries manufactured in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention will now be described in further detail to aid in its understanding.

[0025] The terms and phrases used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to best explain his / her invention.

[0026] [All-solid battery] The present invention relates to an all-solid-state battery.

[0027] The all-solid-state battery according to the present invention includes a unit cell, the unit cell including a cathode layer, a solid electrolyte layer formed on the cathode layer, and an anode layer formed on the solid electrolyte layer, the cathode layer including a cathode current collector having a receiving portion formed therein for receiving a portion of the cathode active material layer, and the cathode active material layer received in the receiving portion, and the solid electrolyte layer being formed in contact with the cathode current collector and the cathode active material layer.

[0028] The unit cell has a rectangular parallelepiped shape, and the cross-sectional areas of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are the same. Here, the cross-section of the positive electrode layer may be the cross-section of a positive electrode current collector, the cross-section of a portion including the positive electrode active material layer and the positive electrode current collector in contact with the positive electrode active material layer, or the cross-section of the positive electrode active material layer and the solid electrolyte layer in contact with the positive electrode active material layer.

[0029] Furthermore, since the unit cell does not include any foreign materials or voids other than the positive electrode layer, the solid electrolyte layer, and the negative electrode layer, problems such as structural instability and deterioration of battery performance due to foreign materials or voids can be prevented. Therefore, the unit cell of the all-solid-state battery may be composed of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer.

[0030] In one embodiment of the present invention, two or more unit cells may be stacked.

[0031] In the case of a stack cell in which two or more unit cells are stacked, no different materials or voids are contained. The stack cell may also have a rectangular parallelepiped shape.

[0032] FIG. 2 is a schematic diagram showing a vertical cross section of an all-solid-state battery according to an embodiment of the present invention.

[0033] Referring to Figure 2, the all-solid-state battery (10) may be in the form of a stack cell (200) in which two unit cells (100) are stacked. The positive electrode active material layer (112) is relatively smaller in size than the solid electrolyte layer (120) and the negative electrode layer (130). By designing the periphery of the positive electrode active material layer (112) to be surrounded by the positive electrode current collector (111) and the solid electrolyte layer (120), it is possible to compensate for the difference in size between the positive electrode active material layer (112), the solid electrolyte layer (120), and the negative electrode layer (130).

[0034] The positive electrode current collector (111) includes a body portion (111a) and a housing portion (111b) that houses the positive electrode active material layer (112). The housing portion (111b) is formed in a recessed shape in the body portion (111a). A portion of the positive electrode active material layer (112) is housed in the housing portion (111b). The positive electrode active material layer (112) housed in the housing portion (111b) is surrounded by the positive electrode current collector (111).

[0035] Of the side lengths (H1+H2) of the positive electrode active material layer (112), the length (H1) of the side in contact with the positive electrode current collector (111) may be smaller than the length (H2) of the side in contact with the solid electrolyte layer (120). If the length (H1) of the side in contact with the positive electrode current collector (111) is large, the possibility of contact with the negative electrode layer (130) increases, which may cause a short circuit.

[0036] Since a portion of the positive electrode active material layer (112) is accommodated in the accommodation portion (111b), the remaining portion of the positive electrode active material layer (112) not accommodated in the accommodation portion (111b) is surrounded by the solid electrolyte layer (120). The solid electrolyte layer (120) is formed on the positive electrode active material layer (112). The solid electrolyte layer (120) is formed in a shape that surrounds the remaining portion of the positive electrode active material layer (112) not accommodated in the accommodation portion (111b). Therefore, the solid electrolyte layer (120) is also formed on the body portion (111a) of the positive electrode current collector (111) excluding the accommodation portion (111b).

[0037] The positive electrode active material layer (112), which is relatively smaller in size than the solid electrolyte layer (120) and the negative electrode layer (130), is surrounded by the positive electrode current collector (111) and the solid electrolyte layer (120), and the step due to the difference in size is compensated for, so that the unit cell (100) has a rectangular parallelepiped shape. As a result, the stack cell (200) formed by stacking the unit cells (100) also has a rectangular parallelepiped shape.

[0038] When a pressure process is performed by applying pressure in a certain direction to a rectangular parallelepiped unit cell 100 or stack cell 110, problems such as cracks and elongation of the positive electrode can be prevented, thereby ensuring structural stability. Furthermore, since the positive electrode does not elongate in a uniform shape but rather expands while exhibiting irregularity, it is difficult to ensure the desired shape and area. However, in the present invention, elongation of the positive electrode can be prevented, so the positive electrode can be controlled to the desired shape and area.

[0039] In one embodiment of the present invention, the height of the storage section may be smaller than the height of the positive electrode active material layer.

[0040] Since only a portion of the positive electrode active material layer is accommodated in the accommodation portion, it may be preferable that the height of the accommodation portion is smaller than the height of the positive electrode active material layer. By accommodating the positive electrode active material layer in the accommodation portion, the positive electrode active material layer is fixed in shape by the positive electrode active material layer, which has the effect of preventing the positive electrode from elongating even during the pressing step.

[0041] In one embodiment of the present invention, a part of a side surface of the positive electrode active material layer is in contact with a positive electrode current collector and a part of the side surface is in contact with a solid electrolyte layer, and the length of the side surface of the positive electrode active material layer that is in contact with the positive electrode current collector may be shorter than the length of the side surface that is in contact with the solid electrolyte layer.

[0042] When the side surface of the positive electrode active material layer is used as a reference, a portion of the side surface of the positive electrode active material layer is accommodated in a housing portion of the positive electrode current collector and contacts the positive electrode current collector, and the remaining portion is in contact with the solid electrolyte layer. If the length of the side surface of the positive electrode active material layer that is in contact with the positive electrode current collector is longer than the length that is in contact with the solid electrolyte layer, the probability that the positive electrode current collector will come into contact with the negative electrode increases, which may cause a short circuit.

[0043] 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.

[0044] The positive electrode current collector supports the positive electrode active material layer and serves to transfer electrons between an external conductor and the positive electrode active material layer.

[0045] The positive electrode current collector is not particularly limited as long as it does not cause a chemical change in the all-solid-state battery and has high electronic conductivity. For example, the positive electrode current collector may be made of aluminum, nickel, titanium, palladium, baked carbon, copper, stainless steel, copper or stainless steel whose surface is treated with carbon, nickel, silver, or the like, or an aluminum-cadmium alloy.

[0046] In addition, the positive electrode current collector may have a fine uneven structure on its surface or a three-dimensional porous structure in order to strengthen the bonding strength with the positive electrode active material layer, and thus may have various shapes such as a film, sheet, foil, mesh, net, porous body, foam, or nonwoven fabric.

[0047] The positive electrode active material layer may be formed to have an area smaller than that of the positive electrode current collector and may be positioned on the positive electrode current collector.

[0048] The positive electrode active material layer includes a positive electrode active material, a conductive material, and a binder, and may further include a solid electrolyte.

[0049] The positive electrode active material is not particularly limited as long as it is a material capable of reversibly absorbing and releasing lithium ions. For example, lithium cobalt oxide (LiCoO), lithium nickel oxide (LiNiO), Li[Ni x Co y Mn z M v ]O2 (wherein M is any one or more elements selected from the group consisting of Al, Ga, and In, and 0.3≦x<1.0, 0≦y, z≦0.5, 0≦v≦0.1, and x+y+z+v=1), Li (Li a M b-a-b’ M' b’ )O 2-c A c (wherein 0≦a≦0.2, 0.6≦b≦1, 0≦b'≦0.2, 0≦c≦0.2, M includes Mn and one or more selected from the group consisting of Ni, Co, Fe, Cr, V, Cu, Zn, and Ti, M' is one or more selected from the group consisting of Al, Mg, and B, and A is one or more selected from the group consisting of P, F, S, and N), or compounds substituted with one or more transition metals, such as compounds of the formula Li 1+y Mn 2-yO4 (where y is 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, and LiMnO2, lithium copper oxide (Li2CuO2), vanadium oxides such as LiV3O8, LiFe3O4, V2O5, and Cu2V2O7, and vanadium oxides with the chemical formula LiNi 1-y M y O2 (where M=Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and y is 0.01 to 0.3), 2-y M y Examples of suitable lithium manganese composite oxides include, but are not limited to, lithium manganese composite oxides represented by Li2Mn3MO8 (where M is Co, Ni, Fe, Cr, Zn, or Ta, and y is 0.01 to 0.1) or Li2Mn3MO8 (where M is Fe, Co, Ni, Cu, or Zn), LiMn2O4 in which part of the Li in the chemical formula is substituted with an alkaline earth metal ion, disulfide compounds, and Fe2(MoO4)3.

[0050] The positive electrode active material may be included in an amount of 60 wt% 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% or more, 65 wt% or more, or 68 wt% or more, or 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 be reduced, and if it exceeds 80 wt%, mass transfer resistance may be increased.

[0051] 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.

[0052] The sulfide-based solid electrolyte may include a compound represented by the following Chemical Formula 1 or a mixture thereof: <Chemical formula 1> Li a M b S c X d In the formula 1, M is selected from P, Sn, Sb, As, and Ge; wherein X is selected from Cl, Br, and I; 5≦a≦7.5, and 0.5 <b≦1.5であり、4<c≦6であり、0.5<d≦2である。

[0053] The halide-based solid electrolyte may be represented by the following chemical formula 2: <Chemical formula 2> Li 6-3a M a Br b Cl c In the above formula 2, M is a metal other than Li, and a is 0. <a<2であり、bは0≦b≦6であり、cは0≦c≦6であり、b+c=6である。

[0054] For example, the halide solid electrolyte may include one or more selected from the group consisting of Li3YBr6, Li3YCl6, and Li3YBr2Cl4.

[0055] The oxide-based solid electrolyte is Li 3x La 2 / 3-x LLT series with perovskite structure such as TiO3, Li 14 LISICON such as Zn(GeO4)4, Li 1.3 Al 0.3 Ti 1.7 LATP systems such as (PO4)3, (Li 1+x Ge 2-x Al x The LAGP type such as (PO4)3) or the phosphate type such as LiPON may be appropriately selected and used, but is not particularly limited to these.

[0056] 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 include graphite or conductive carbon, such as graphite (e.g., natural graphite, artificial graphite, etc.); carbon black (e.g., carbon black, acetylene black, ketjen black, denka black, thermal black, channel black, furnace black, lamp black, summer black, etc.); carbon-based materials with a graphene or graphite crystalline structure; conductive fibers (e.g., carbon fiber, metal fiber, etc.); carbon fluoride; metal powders (e.g., aluminum powder, nickel powder, etc.); conductive whiskers (e.g., zinc oxide, potassium titanate, etc.); conductive oxides (e.g., titanium oxide, etc.); and conductive polymers (e.g., polyphenylene derivatives). These may be used alone or in combination. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0057] 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. 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 conductive material content is too low, such as less than 1 wt %, the effect of improving electrical conductivity may not be expected, or the electrochemical properties of the battery may be degraded. If the conductive material content is too high, such as more than 5 wt %, the amount of positive electrode active material may be relatively small, and the capacity and energy density may be reduced. The method of incorporating the conductive material into the positive electrode is not particularly limited, and may be a conventional method known in the art, such as mixing with the positive electrode active material or coating.

[0058] The binder may be a component that assists in binding the positive electrode active material to the conductive material and the like and in binding to the current collector, and may be selected from the group consisting of styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, The binder may include one or more selected from the group consisting of nitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl sucrose, 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).

[0059] 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. Specifically, the binder content 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 binder content is less than 0.5 wt %, the adhesive strength between the positive electrode active material and the positive electrode current collector may be reduced. If the binder content exceeds 4 wt %, the adhesive strength is improved, but the content of the positive electrode active material may be reduced accordingly, which may reduce the battery capacity.

[0060] In one embodiment of the present invention, the solid electrolyte layer may be larger in area than the positive electrode active material layer, where the areas of the solid electrolyte layer and the positive electrode active material layer mean the areas when the solid electrolyte layer and the positive electrode active material layer are viewed from above.

[0061] The solid electrolyte layer has a shape that envelops the positive electrode active material layer, which increases the lithium ion transfer area and may be advantageous in terms of ion conductivity.

[0062] The solid electrolyte layer may include a sulfide-based solid electrolyte, a halide-based solid electrolyte, or an oxide-based solid electrolyte. From the viewpoint of lithium ion conductivity, the solid electrolyte layer may include a sulfide-based solid electrolyte having an argyrodite-type crystal structure.

[0063] The sulfide-based solid electrolyte may include a compound represented by the following Chemical Formula 1 or a mixture thereof: <Chemical formula 1> Li a M b S c X d In the formula 1, M is selected from P, Sn, Sb, As, and Ge; A is selected from S, Se, and Te; wherein X is selected from Cl, Br, and I; 5≦a≦7.5, and 0.5 <b≦1.5であり、4<c≦6であり、0.5<d≦2である。

[0064] The halide-based solid electrolyte may be represented by the following chemical formula 2: <Chemical formula 2> Li 6-3a M a Br b Cl c In the above formula 2, M is a metal other than Li, and a is 0. <a<2であり、bは0≦b≦6であり、cは0≦c≦6であり、b+c=6である。

[0065] For example, the halide solid electrolyte may include one or more selected from the group consisting of Li3YBr6, Li3YCl6, and Li3YBr2Cl4.

[0066] The oxide-based solid electrolyte is Li 3x La 2 / 3-x LLT series with perovskite structure such as TiO3, Li 14 LISICON such as Zn(GeO4)4, Li 1.3 Al 0.3 Ti 1.7 LATP systems such as (PO4)3, (Li 1+x Ge 2-x Al x The LAGP type such as (PO4)3) or the phosphate type such as LiPON may be appropriately selected and used, but is not particularly limited to these.

[0067] 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.

[0068] Alternatively, the negative electrode layer may include a negative electrode current collector and a non-negative electrode coating layer formed on the negative electrode current collector, and the non-negative electrode coating layer may be stacked so as to be in contact with the solid electrolyte layer.

[0069] The negative electrode active material layer includes a negative electrode active material, a binder, and a conductive material.

[0070] The negative electrode active material is lithium (Li + The lithium ion-containing compound may include a material capable of reversible intercalation or deintercalation of lithium ions, a material capable of reversibly reacting with lithium ions to form a lithium-containing compound, lithium metal, or a lithium alloy.

[0071] The lithium ion (Li +The material capable of reversibly inserting or de-inserting lithium ions (Li) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. + The material capable of reacting with lithium (Li) to reversibly form a lithium-containing compound may be, for example, tin oxide, titanium nitrate, or silicon. The lithium alloy may 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).

[0072] Preferably, the negative electrode active material may be lithium metal or a lithium-indium alloy (Li-In), specifically, lithium metal or lithium thin film, lithium-indium alloy thin film, or powder.

[0073] The negative electrode active material may be included in an amount of 40 wt % 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, or 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 mass transfer resistance may be increased.

[0074] The binder may be a component that assists in binding the negative electrode active material to the conductive material and the like and in binding the negative electrode current collector, and may be any of the following: styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylic The binder may include one or more selected from the group consisting of fluorocarbon nitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl sucrose, 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).

[0075] 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. Specifically, the binder content 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 binder content is less than 0.5 wt %, the adhesive strength between the positive electrode active material and the negative electrode current collector may be reduced. If the binder content exceeds 4 wt %, the adhesive strength is improved, but the content of the negative electrode active material may be reduced accordingly, which may reduce the battery capacity.

[0076] 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 include graphite or conductive carbon, such as graphite (e.g., natural graphite, artificial graphite, etc.); carbon black (e.g., carbon black, acetylene black, ketjen black, denka black, thermal black, channel black, furnace black, lamp black, summer black, etc.); carbon-based materials with a graphene or graphite crystalline structure; conductive fibers (e.g., carbon fiber, metal fiber, etc.); carbon fluoride; metal powder (e.g., aluminum powder, nickel powder, etc.); conductive whiskers (e.g., zinc oxide, potassium titanate, etc.); conductive oxides (e.g., titanium oxide, etc.); and conductive polymers (e.g., polyphenylene derivatives). These may be used alone or in combination. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0077] 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. 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 conductive material content is too low, such as less than 1 wt %, the effect of improving electronic conductivity may not be expected, or the electrochemical properties of the battery may be degraded. If the conductive material content is too high, such as more than 5 wt %, the amount of negative electrode active material may be relatively small, resulting in reduced capacity and energy density. The method for incorporating the conductive material into the negative electrode is not particularly limited, and may be a conventional method known in the art, such as mixing or coating with the negative electrode active material.

[0078] The negative electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and is conductive, and may be, for example, copper, stainless steel, aluminum, nickel, titanium, baked carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, aluminum-cadmium alloy, etc. Similarly to the positive electrode current collector, the negative electrode current collector may be in various forms such as a film, sheet, foil, net, porous material, foam, nonwoven fabric, or the like having fine irregularities formed on the surface.

[0079] The method for manufacturing the negative electrode is not particularly limited, and the negative electrode may be manufactured by forming a negative electrode active material layer on a negative electrode current collector using a layer or film formation method commonly used in the art. For example, methods such as compression bonding, coating, and vapor deposition may be used. In addition, the negative electrode of the present invention also includes a case where a lithium thin film is formed on the metal plate by initial charging after assembling a battery without a lithium thin film on the negative electrode current collector.

[0080] Furthermore, the non-anode coating layer does not contain an anode active material, and an anode active material may be formed in the non-anode coating layer upon charging. For example, lithium ions may migrate from the positive electrode during charging of the battery, causing lithium metal to be deposited on the negative electrode. In other words, the non-anode coating layer may be a film that induces lithium deposition.

[0081] The non-anode coating layer may include metal particles and carbon particles, specifically, a carbon-metal composite.

[0082] The carbon particles may be, for example, amorphous carbon particles. However, the carbon particles are not limited to amorphous particles. Specific examples of the amorphous carbon material include carbon black such as acetylene black, furnace black, and ketjen black, graphene, or a combination thereof.

[0083] The metal particles may be particles that form an alloy with lithium, and may be particles of one or more types selected from silver (Ag), gold, platinum, palladium, silicon, aluminum, bismuth, tin, indium, and zinc. The non-negative electrode coating layer may be formed as a very thin film with a micron thickness, for example, with a thickness of 10 μm or less.

[0084] Preferably, the non-negative electrode coating layer may include an Ag-C composite as the carbon material-metal composite, and lithium may be deposited between the negative electrode current collector and the coating layer containing the Ag-C composite during the first charge.

[0085] In one embodiment of the present invention, the all-solid-state battery may be a pouch-type all-solid-state battery.

[0086] [Manufacturing method for all-solid-state batteries] The present invention also relates to a method for manufacturing an all-solid-state battery.

[0087] 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): (S1) forming a positive electrode active material layer on a positive electrode current collector having an accommodation portion formed thereon for accommodating a part of the positive electrode active material layer; (S2) forming a solid electrolyte layer on the positive electrode current collector and the positive electrode active material layer excluding the housing portion; (S3) forming a negative electrode layer on the solid electrolyte layer; and (S4) A step of applying pressure in the stacking direction of the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer to bond them together.

[0088] The constituent materials and shapes of the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer are the same as those described above.

[0089] Hereinafter, each step of the method for manufacturing an all-solid-state battery according to the present invention will be described in more detail.

[0090] In one embodiment of the present invention, in the step (S1), the positive electrode active material layer may be formed on a positive electrode current collector having a receiving portion formed thereon for receiving a part of the positive electrode active material layer.

[0091] The positive electrode active material layer may be manufactured by a wet process or a dry process, and the positive electrodes manufactured by the manufacturing process of the positive electrode active material layer may be called a wet positive electrode or a dry positive electrode, respectively.

[0092] When the wet process is performed, the positive electrode active material layer can be formed by coating a positive electrode active material layer-forming slurry on a positive electrode current collector. Specifically, the positive electrode active material layer can be formed by mixing a positive electrode active material, a conductive material, and a binder in an organic solvent to prepare a positive electrode active material layer-forming slurry, which can be coated on a housing portion of the positive electrode current collector and dried. In this case, it is preferable to use an organic solvent that can uniformly disperse the positive electrode active material, the binder, and the conductive material and that easily evaporates. Specific examples of the organic solvent include acetonitrile, methanol, ethanol, tetrahydrofuran, water, and isopropyl alcohol.

[0093] In addition, when the dry process is performed, the cathode active material layer may be formed by separately preparing a sheet, punching out the sheet to a size that fits into the receiving portion of the cathode current collector, and joining the sheet to the receiving portion of the cathode current collector. In this case, the sheet may be prepared by a conventional method using the above-described slurry for forming the cathode active material layer.

[0094] In one embodiment of the present invention, in the step (S2), a solid electrolyte layer can be formed on the positive electrode current collector and the positive electrode active material layer excluding the housing portion.

[0095] The positive electrode current collector includes a body portion and a receiving portion formed by engraving in the body portion. A positive electrode active material layer is formed in the receiving portion. Therefore, when the solid electrolyte layer is formed on the positive electrode active material layer, the solid electrolyte layer can also be formed on the body portion of the positive electrode current collector excluding the receiving portion.

[0096] The solid electrolyte layer may be prepared by coating a slurry obtained by mixing a solid electrolyte and a binder in a solvent onto the positive electrode active material layer and then drying the coating.

[0097] As described above, the solid electrolyte may include one or more selected from the group consisting of a sulfide-based solid electrolyte, a halide-based solid electrolyte, and an oxide-based solid electrolyte. Preferably, the solid electrolyte may include a sulfide-based solid electrolyte having an argyrodite-type crystal structure.

[0098] The binder resin may contain at least one selected from the group consisting of acrylic copolymers, acrylic block copolymers, and random copolymers of acrylic monomers or oligomers.

[0099] The binder may be included in an amount of 5 to 15 parts by weight per 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, ion conductivity may decrease.

[0100] The solvent is not particularly limited as long as it dissolves and / or disperses 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, N-methylpyrrolidone (NMP), acetone, xylene, N,N-dimethylformamide (DMF), benzene, tetrahydrofuran (THF), and water. The amount of the solvent used may be adjusted taking into account the thickness of the coating layer and the physical properties of the solid electrolyte to be produced.

[0101] The 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 to these as long as it is a method that can form a layer by coating.

[0102] The drying method is not particularly limited as long as it can evaporate the solvent after coating to form a layer. For example, the drying may be performed at 300°C or less. Specifically, the drying temperature may be 300°C or less, 200°C or less, 150°C or less, or 100°C or less.

[0103] In one embodiment of the present invention, in the step (S3), a negative electrode layer may be formed on the solid electrolyte layer.

[0104] The method for forming the negative electrode layer on the solid electrolyte layer is not particularly limited as long as it is a method commonly used in the industry, and a method such as lamination may be used.

[0105] 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 may be bonded by applying pressure in the direction in which they are stacked.

[0106] The step (S4) indicates a process of pressurizing the unit cells after manufacturing them, but the pressurization may be performed after manufacturing the stack cells, or after putting them into an exterior material.

[0107] The pressure may be 400 MPa to 700 MPa, specifically, 400 MPa or more, 450 MPa or more, or 500 MPa or more, and may be 600 MPa or less, 650 MPa or less, or 700 MPa or less. If the pressure is less than 400 MPa, the pressure may be insufficient to produce an all-solid-state battery, or pores may remain inside the positive electrode, increasing the resistance. If the pressure is more than 700 MPa, excessive pressure may act, causing cracks in parts of the battery.

[0108] Preferred examples will be described below to aid in understanding the present invention. However, the following examples are merely illustrative of the present invention, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope of the scope and technical idea of ​​the present invention. Naturally, such changes and modifications also fall within the scope of the appended claims.

[0109] [Example 1] An all-solid-state battery (10) having a cross-sectional structure as shown in FIG. 3a was manufactured.

[0110] An aluminum foil was prepared as the positive electrode current collector 111. The aluminum foil had a body portion and a receiving portion formed by intaglio engraving on the body portion.

[0111] A dry sheet containing NMC(Ni, Co, Mn)O2 was attached to the receiving portion, and then a positive electrode active material layer (112) was formed thereon to prepare a positive electrode layer (110).

[0112] Then, a solid electrolyte forming slurry was dip-coated onto the body portion (excluding the housing portion) of the positive electrode current collector (111) and the positive electrode active material layer (112), and then dried to form a solid electrolyte layer (120). The solid electrolyte forming slurry was prepared by mixing a sulfide-based solid electrolyte having an argyrodite-based crystal structure and a rubber-based binder in a 1:1 weight ratio, and then adding the mixture to an N-methylpyrrolidone (NMP) solvent.

[0113] The positive electrode active material layer (112) was configured to be surrounded by the positive electrode current collector (111) and the solid electrolyte layer (120). The length of the side surface of the positive electrode active material layer (112) in contact with the positive electrode current collector (111) was made shorter than the length of the side surface of the positive electrode active material layer (112) in contact with the solid electrolyte layer (120).

[0114] Then, an anode layer (130) was laminated on the solid electrolyte layer (120) and pressurized at a pressure of 500 MPa to manufacture a unit cell type all-solid-state battery (10). The anode layer (130) was anodeless, and used was an Ag-C composite formed on one side of a Cu current collector.

[0115] [Example 2] An all-solid-state battery (10) having a cross-sectional structure as shown in Figure 3b was manufactured.

[0116] An aluminum foil was prepared as the positive electrode current collector 111. The aluminum foil had a body portion and a receiving portion formed by intaglio engraving on the body portion.

[0117] The receiving portion was coated with a slurry containing NMC (Ni, Co, Mn) O2 to form a positive electrode active material layer (112), thereby manufacturing a positive electrode (110).

[0118] Then, a solid electrolyte forming slurry was dip-coated onto the body portion (excluding the housing portion) of the positive electrode current collector (111) and the positive electrode active material layer (112), and then dried to form a solid electrolyte layer (120). The solid electrolyte forming slurry was prepared by mixing a sulfide-based solid electrolyte having an argyrodite-based crystal structure and a rubber-based binder in a 1:1 weight ratio, and then adding the mixture to an N-methylpyrrolidone (NMP) solvent.

[0119] The positive electrode active material layer (112) was configured to be surrounded by the positive electrode current collector (111) and the solid electrolyte layer (120). The length of the side surface of the positive electrode active material layer (112) in contact with the positive electrode current collector (111) was made shorter than the length of the side surface of the positive electrode active material layer (112) in contact with the solid electrolyte layer (120).

[0120] Then, an anode layer 130 was laminated on the solid electrolyte layer 120 and pressurized at a pressure of 500 MPa to manufacture a unit cell type all-solid-state battery 10. The anode layer was anodeless, and an Ag-C composite was formed on one side of a Cu current collector.

[0121] [Comparative Example 1] An all-solid-state battery with a cross-sectional structure as shown in Figure 3c was fabricated.

[0122] The positive electrode layer (110), the solid electrolyte layer (120), and the negative electrode layer (130) were stacked and then pressed at a pressure of 500 MPa to produce an all-solid-state battery (10). Here, the positive electrode layer (110), the solid electrolyte layer (120), and the negative electrode layer (130) were all sheet-shaped, and their sizes were arranged in the order of positive electrode layer (110) < negative electrode layer (130) < solid electrolyte layer (120). The constituent materials of the positive electrode layer (110), the solid electrolyte layer (120), and the negative electrode layer (130) were the same as in Example 2.

[0123] Comparative Example 2 An all-solid-state battery with a cross-sectional structure as shown in Figure 3d was fabricated.

[0124] An all-solid-state battery was manufactured in the same manner as in Comparative Example 1, except that the sizes of the positive electrode layer (110), the solid electrolyte layer (120), and the negative electrode layer (130) were all the same.

[0125] [Experimental Example 1: Performance evaluation experiment of all-solid-state batteries] We conducted experiments to evaluate the performance of all-solid-state batteries.

[0126] To evaluate the performance of the all-solid-state battery, the discharge capacity was measured by cycles under the condition of 0.33 C / 0.33 C, and the life characteristics were evaluated.

[0127] As a result, as shown in Fig. 4, it can be seen that Examples 1 and 2 have significantly better life characteristics than Comparative Examples 1 and 2. It can be seen that such results are due to the structural stability of the all-solid-state battery.

[0128] [Experimental Example 2: Checking for cracks] It was confirmed whether cracks occurred in the all-solid-state battery due to the pressurizing process.

[0129] The cross sections of the unit cells of Examples 1 and 2 and Comparative Examples 1 and 2 were observed with a scanning electron microscope (SEM).

[0130] 5a to 5c show scanning electron microscope (SEM) photographs of cross sections of the all-solid-state batteries manufactured in the examples and comparative examples.

[0131] FIG. 5a shows that the cross section of the battery is generally free of damage, including cracks.

[0132] 5b and 5c, it can be seen that the positive electrode layer (110) is stretched and cracks are generated, and the cracks are generated in the positive electrode layer (110) and extend to the solid electrolyte layer (130).

[0133] Although the present invention has been described above using limited examples and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims set forth below. [Explanation of symbols]

[0134] 10: All-solid-state battery 100: unit cell 110: Positive electrode layer 111: Positive electrode current collector 111a: Body part, 111b: Containment unit 112: Positive electrode active material layer 120: Solid electrolyte layer 130: Negative electrode layer 131:Negative electrode current collector 132:Negative electrode active material layer 200: Stack Cell C: Crack D: Collapse

Claims

1. An all-solid-state battery including a unit cell, the unit cell includes a positive electrode layer, a solid electrolyte layer formed on the positive electrode layer, and a negative electrode layer formed on the solid electrolyte layer; the positive electrode layer includes a positive electrode current collector having a receiving portion formed therein for receiving a portion of the positive electrode active material layer, and the positive electrode active material layer received in the receiving portion, The solid electrolyte layer is formed in contact with the positive electrode current collector and the positive electrode active material layer.

2. The all-solid-state battery according to claim 1 , wherein the height of the housing portion is smaller than the height of the positive electrode active material layer.

3. a portion of a side surface of the positive electrode active material layer is in contact with the positive electrode current collector, The remaining portion is in contact with the solid electrolyte layer, 2. The all-solid-state battery according to claim 1, wherein a portion of the side surface of the positive electrode active material layer that is in contact with the positive electrode current collector is smaller than a portion that is in contact with the solid electrolyte layer.

4. the negative electrode layer includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector, 2. The all-solid-state battery according to claim 1, wherein the negative electrode active material layer is laminated so as to be in contact with the solid electrolyte layer.

5. the negative electrode layer includes a negative electrode current collector and a non-negative electrode coating layer formed on the negative electrode current collector; 2. The all-solid-state battery according to claim 1, wherein the non-anode coating layer is laminated so as to be in contact with the solid electrolyte layer.

6. The all-solid-state battery according to any one of claims 1 to 5, wherein the unit cells are formed by stacking two or more unit cells.

7. (S1) forming a positive electrode active material layer on a positive electrode current collector having an accommodation portion formed thereon for accommodating a part of the positive electrode active material layer; (S2) forming a solid electrolyte layer on the positive electrode current collector and the positive electrode active material layer excluding the housing portion; (S3) forming a negative electrode layer on the solid electrolyte layer; (S4) applying pressure to the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer in a stacking direction to bond them together; A method for manufacturing an all-solid-state battery, comprising a unit cell manufacturing process comprising:

8. The method for producing an all-solid-state battery according to claim 7 , wherein the pressure is 400 MPa or more and 700 MPa or less.

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