Solid electrolyte membrane and all-solid-state battery containing the same

Abstract

The present invention relates to a solid electrolyte membrane and an all-solid-state battery including the same, and more particularly, the solid electrolyte membrane is manufactured by a dry process in which sulfide-based and / or halide-based solid electrolyte particles and a binder are physically mixed. The fibrous binder formed by fiberizing the binder in the dry process is contained in a state in which the fibrous binder is intertwined with each other, so that even a small amount of binder can show an effect of improving ion conductivity and strength.

Description

[Technical Field]

[0001] This application claims priority under Korean Patent Application No. 10-2022-0182670 dated December 23, 2022, and all content disclosed in the said Korean Patent Application is incorporated herein as part of this specification.

[0002] This invention relates to a solid electrolyte membrane and an all-solid-state battery containing the same. [Background technology]

[0003] From the perspectives of battery capacity, safety, output, scaling up, and miniaturization, various types of batteries are currently being researched that can overcome the limitations of lithium-ion secondary batteries.

[0004] Typically, metal-air batteries, which have a much larger theoretical capacity than lithium-ion batteries; all-solid-state batteries, which pose no risk of explosion in terms of safety; supercapacitors, which offer high output; NaS batteries or RFB (redox flow batteries), which are designed for larger sizes; and thin-film batteries, which are designed for ultra-miniaturization, are among the technologies that are being continuously researched in academia and industry.

[0005] All-solid-state batteries are batteries that replace the liquid electrolyte used in conventional lithium-ion secondary batteries with a solid electrolyte. Because they do not use flammable solvents within the battery, there is no risk of ignition or explosion due to the decomposition reaction of conventional electrolytes, thus significantly improving safety. Furthermore, because lithium metal or lithium alloy can be used as the negative electrode material, there is an advantage in that the energy density relative to the mass and volume of the battery can be dramatically improved.

[0006] However, although all-solid-state batteries can ensure safety by using the solid electrolyte, the ionic conductivity may decrease. In addition, when a liquid electrolyte is used together as a means to ensure the ionic conductivity of the solid electrolyte, there is a problem that the strength decreases.

[0007] Generally, in order to ensure the safety of all-solid-state batteries and at the same time prevent the performance and processability of the batteries from degrading, both the ionic conductivity and strength of the solid electrolyte must be maintained above a certain level.

[0008] However, among the solid electrolytes developed to date, the technical development results for solid electrolytes that ensure all physical properties with respect to ionic conductivity and strength are negligible.

[0009] As the demand for all-solid-state batteries increases, the demand for solid electrolytes contained in all-solid-state batteries also proportionally increases. Therefore, it is necessary to develop solid electrolytes with excellent ionic conductivity and strength.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] As a result of conducting extensive research to solve the above problems, the inventors have confirmed that a solid electrolyte membrane with improved ionic conductivity and strength can be produced by a structure in which fibrous binders formed by a dry process of physically mixing a sulfide-based solid electrolyte and / or a halide-based solid electrolyte and a binder are dispersed and intertwined.

[0012] Therefore, an object of the present invention is to provide a solid electrolyte membrane with improved ionic conductivity and strength.

[0013] Another object of the present invention is to provide an all-solid-state battery including a solid electrolyte membrane with improved ionic conductivity and strength.

Means for Solving the Problems

[0014] To achieve the above object, the present invention provides a solid electrolyte membrane including a solid electrolyte and a fiberized binder, wherein the solid electrolyte includes one or more selected from the group consisting of a sulfide-based solid electrolyte and a halide-based solid electrolyte.

[0015] The present invention also provides a solid electrolyte membrane, wherein the sulfide-based solid electrolyte is represented by the following Chemical Formula 1: [Chemical Formula 1] L

[0016] , b , , 6-3a ,

[0017] , d1 , , , c , , a , e1 , c1 ,<00001​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ The present invention also provides a solid electrolyte membrane in which the solid electrolyte is present in an amount of 98% by weight or more, based on the total weight of the solid electrolyte membrane.

[0018] The present invention also provides a solid electrolyte membrane in which the fibrous binder comprises one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and copolymers containing the same.

[0019] The present invention also provides a solid electrolyte membrane in which the fibrous binder is contained in an amount of 2% by weight or less, based on the total weight of the solid electrolyte membrane.

[0020] The present invention also provides a solid electrolyte membrane in which the fibrous binder is contained in a dispersed state within the solid electrolyte membrane.

[0021] The present invention also provides a solid electrolyte membrane in which the interface between the solid electrolyte and the fibrous binder is bonded.

[0022] The present invention also provides a solid electrolyte membrane having an ionic conductivity of 0.5 to 10 mS / cm.

[0023] The present invention also provides a solid electrolyte membrane having a tensile strength of 45 to 1000 kPa.

[0024] The present invention also provides a solid electrolyte membrane that is solvent-free.

[0025] The present invention also provides an all-solid-state battery comprising a positive electrode, a negative electrode, and the solid electrolyte membrane interposed between them. [Effects of the Invention]

[0026] The solid electrolyte membrane according to the present invention consists of sulfide-based and / or halide-based solid electrolyte particles and a fibrous binder. Because it contains a small amount of fibrous binder, the content of solid electrolyte particles is relatively high, which can improve ionic conductivity.

[0027] Furthermore, since the solid electrolyte membrane contains a fibrous binder in which the binder is fibroused during a dry process in which physical mixing takes place without the use of a solvent, it can exhibit excellent tensile strength even when only a small amount of the fibrous binder is used. [Brief explanation of the drawing]

[0028] [Figure 1] This is a schematic diagram showing the internal structure of a solid electrolyte membrane according to one embodiment of the present invention. [Figure 2] This is a scanning electron microscope (SEM) image of a solid electrolyte membrane according to one embodiment of the present invention. [Figure 3] This graph shows the correlation between the content of fibrous binder in a solid electrolyte membrane according to one embodiment of the present invention, ionic conductivity, and tensile strength. [Modes for carrying out the invention]

[0029] The present invention will be described in more detail below to aid in understanding the invention.

[0030] The terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner and concept consistent with the technical idea of ​​the present invention, based on the principle that inventors may appropriately define the concepts of terms in order to best describe their inventions.

[0031] As used herein, the term "crosslinked structure" refers to a structure formed by the entanglement of fibrous binders dispersed in a solid electrolyte membrane, and may be a three-dimensional structure including a frame made of fibrous binders and an internal space formed by the frame.

[0032] solid electrolyte membrane This invention relates to a solid electrolyte membrane.

[0033] The solid electrolyte membrane according to the present invention comprises a solid electrolyte and a fibrous binder, wherein the solid electrolyte comprises one or more selected from the group consisting of sulfide-based solid electrolytes and halide-based solid electrolytes.

[0034] Figure 1 is a schematic diagram showing the internal structure of a solid electrolyte membrane according to one embodiment of the present invention.

[0035] Referring to Figure 1, within the solid electrolyte membrane (1), the solid electrolyte (10) may exist in a particulate state, and the fibrous binder (20) may be included in an intertwined state. Specifically, the fibrous binder (20) can form a dispersed, intertwined crosslinked structure. This crosslinked structure includes a frame made of the fibrous binder (20) and voids, which are spaces between the frames, in which solid electrolyte (10) particles can be located. The solid electrolyte (10) may be a sulfide-based and / or halide-based solid electrolyte.

[0036] In one embodiment of the present invention, the interface between the solid electrolyte and the fibrous binder may be bonded.

[0037] Since the interface between the solid electrolyte and the fibrous binder is firmly bonded by the pressure applied during the manufacturing process, it is possible to prevent a decrease in the strength of the solid electrolyte membrane even if a small amount of the fibrous binder is used. Furthermore, since adhesion also occurs between the solid electrolytes, this may be even more advantageous in improving the strength of the solid electrolyte membrane.

[0038] In one embodiment of the present invention, the ionic conductivity of the solid electrolyte membrane may be 0.5 to 10 mS / cm. Specifically, the ionic conductivity may be 0.5 mS / cm or more, 0.6 mS / cm or more, 0.8 mS / cm or more, 1 mS / cm or more, 1.5 mS / cm or more, or 2 mS / cm or more, and may be 3 mS / cm or less, 5 mS / cm or less, 8 mS / cm or less, or 10 mS / cm or less. The ionic conductivity may be measured at room temperature (25°C).

[0039] In one embodiment of the present invention, the tensile strength of the solid electrolyte membrane may be 45 to 1000 kPa. It may be 45 kPa or more, 50 kPa or more, 80 kPa or more, 100 kPa or more, 120 kPa or more, or 150 kPa or more, and may be 200 kPa or less, 300 kPa or less, 500 kPa or less, 700 kPa or less, 900 kPa or less, or 1000 kPa or less.

[0040] In one embodiment of the present invention, the solid electrolyte membrane may be solvent-free.

[0041] Since the solid electrolyte membrane is manufactured by a dry process in which the sulfide-based and / or halide-based solid electrolyte and binder are physically mixed, it contains no solvent whatsoever. Furthermore, the binder is fibrousized by the pressurization during the dry process, and the fibrous binder disperses and intertwines with each other, forming a cross-linked bonding structure. As a result, even when only a small amount of the binder is used, a solid electrolyte membrane with improved strength can be manufactured due to the structure formed by the fibrous binder.

[0042] Furthermore, since no separate solvent is used, it is possible to prevent the phenomenon in which the crystalline structure of sulfide-based and / or halide-based solid electrolytes is destroyed by the solvent, resulting in a decrease in ionic conductivity.

[0043] Generally, the wet process carried out for the manufacture of solid electrolyte membranes uses a solvent capable of dissolving a binder, which then lies between the solid electrolyte particles and provides adhesion.

[0044] On the other hand, the dry process according to the present invention does not use a solvent and physically stretches the binder in its initial particle form to form fibers. Therefore, the structure of the binder in the manufactured solid electrolyte membrane differs from the structure formed by the wet process, and the physical properties of the solid electrolyte membrane can be improved compared to solid electrolyte membranes manufactured by the wet process. As mentioned above, the binder in its initial particle form undergoes physical deformation due to shear force when mixed with electrolyte particles. To induce such physical deformation, a mortar and pestle, ball mill, or roll press can be introduced during mixing. Furthermore, as a binder that can effectively induce physical deformation, a binder that is physically very weak and relatively prone to fiber formation, such as PTFE, can be used.

[0045] In one embodiment of the present invention, the solid electrolyte may include a sulfide-based solid electrolyte and / or a halide-based solid electrolyte.

[0046] Furthermore, the solid electrolyte may be present in an amount of 98% by weight or more, based on the total weight of the solid electrolyte membrane. Specifically, the content of the solid electrolyte may be 98% by weight or more, 98.5% by weight or more, or 99% by weight or more. If the content of the solid electrolyte is less than 98% by weight, the ionic conductivity of the solid electrolyte membrane may decrease. Also, there is no particular upper limit to the content of the solid electrolyte, but for example, it may be 99.8% by weight or less. If it exceeds 99.8% by weight, the binder content will relatively decrease, and the tensile strength may decrease somewhat.

[0047] Furthermore, the solid electrolyte may be particulate, and its particle size (D50) may be between 10 nm and 10 μm. Specifically, it may be 10 nm or more, 100 nm or more, 300 nm or more, 500 nm or more, 800 nm or more, 1 μm or more, 2 μm or more, or 3 μm or more, and may be 5 μm or less, 7 μm or less, 9 μm or less, or 10 μm or less. If the particle size (D50) of the solid electrolyte is less than 10 nm, the tensile strength may decrease, and if it exceeds 10 μm, the surface of the solid electrolyte film may not be uniform, which may increase the resistance with the electrode.

[0048] In one embodiment of the present invention, the sulfide-based solid electrolyte may be represented by the following chemical formula 1: [Chemical formula 1]

[0049] L a1 M b1 P c1 S d1 A e1 In the above chemical formula 1, L is an element selected from Li, Na, and K, M is an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge, A represents I, Br, Cl, or F, a1, b1, c1, d1, and e1 represent the composition ratio of each element, and a1:b1:c1:d1:e1 is 1~12:0~1:1:2~12:0~5.

[0050] For example, the sulfide-based solid electrolyte may include one or more selected from the group consisting of LiPSX (X=Cl, Br, or I)-based solid electrolytes, LiGePS-based solid electrolytes, and LiPS-based solid electrolytes. However, the sulfide-based solid electrolyte is not limited to these, and a wide range of sulfide-based solid electrolytes commonly used in the industry can be used. For example, the LiPSX (X=Cl, Br, or I) may be Li6PS5Cl.

[0051] In one embodiment of the present invention, the halide-based solid electrolyte may be represented by the following chemical formula 2: [Chemical formula 2] Li 6-3a Ma Br b Cl c In the chemical formula 2, M is a metal other than Li, 0 < a < 2, 0 ≤ b ≤ 6, 0 ≤ c ≤ 6, and b + c = 6. Further, the M may be Y, In, or Zr.

[0052] For example, the halide-based solid electrolyte may contain one or more selected from the group consisting of Li3YBr6, Li3YCl6, and Li3YBr2Cl4.

[0053] In one embodiment of the present invention, the binder is fibrillated during a dry process in which it is physically mixed and pressed with the sulfide-based and / or halide-based solid electrolyte, and the fibrous binder can form a cross-linked structure in a dispersed and intertwined state with each other.

[0054] The binder may be one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and copolymers containing the same, but is not limited thereto, and a binder having a low ductility strength and being easily stretched during the dry process and capable of being fibrillated into a fibrous binder can be widely used.

[0055] Further, the binder may be contained at 2% by weight or less based on the total weight of the solid electrolyte membrane. Specifically, the content of the binder may be 2% by weight or less, 1.5% by weight or less, or 1% by weight or less. When the content of the binder exceeds 2% by weight, the ionic conductivity of the solid electrolyte membrane may decrease. The lower limit of the binder is not particularly limited, but for example, it may be 0.2% by weight or more, and when it is less than 0.2% by weight, the tensile strength may decrease somewhat.

[0056] [[ID=​​​​​​The method for producing a solid electrolyte membrane according to the present invention includes the step of mixing a solid electrolyte and a binder. The solid electrolyte comprises one or more selected from the group consisting of sulfide-based solid electrolytes and halide-based solid electrolytes. The solid electrolyte may be in particulate form.

[0058] At this time, the type, content, and characteristics of the solid electrolyte and binder are as described above.

[0059] Furthermore, since the solid electrolyte and the binder are physically mixed without any separate chemical reaction, the mixing can be described as physical mixing. The mixing can be carried out by mortar and pestle, ball mixing, or roll pressing. Conditions such as mixing time, number of repetitions, or the addition of a heating step can be appropriately set to facilitate the fiberization of the binder.

[0060] all solid state battery The present invention also relates to an all-solid-state battery comprising the solid electrolyte membrane.

[0061] The all-solid-state battery according to the present invention includes a solid electrolyte membrane; a positive electrode formed on one surface of the solid electrolyte membrane; and a negative electrode formed on the other surface of the solid electrolyte.

[0062] In one embodiment of the present invention, the positive electrode may include a positive electrode active material, a conductive material, and a binder.

[0063] In the present invention, the positive electrode included in the all-solid-state battery includes a positive electrode active material layer, and the positive electrode active material layer may be formed on one surface of the positive electrode current collector.

[0064] The positive electrode active material layer comprises a positive electrode active material, a conductive material, and a binder.

[0065] Furthermore, the positive electrode active material is not particularly limited as long as it is a material capable of reversibly intercalating and releasing lithium ions, for example, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), Li[Ni x Co y Mn z M v ]O2(In the above formula, M is one 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 Layered compounds such as (wherein the above formula, 0≦a≦0.2, 0.6≦b≦1, 0≦b'≦0.2, 0≦c≦0.2; M comprises 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; 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 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and y is 0.01-0.3); chemical formula LiMn 2-y M y Lithium manganese composite oxides represented by O2 (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 alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, etc. are examples, but are not limited to these.

[0066] Furthermore, the positive electrode active material may be present in an amount of 60 to 80% by weight, based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 60% by weight, 65% or more by weight, or 68% or more by weight, or 72% or less by weight, 75% or less by weight, or 80% or less by weight. If the content of the positive electrode active material is less than 60% by weight, the battery performance may decrease, and if it exceeds 80% by weight, the mass transfer resistance may be high.

[0067] Furthermore, 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 induce chemical changes in the battery, and has excellent electrical conductivity. Typically, graphite or conductive carbon may be used, for example, graphite such as natural graphite or 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 whose crystalline structure is graphene or graphite; conductive fibers such as carbon fibers and metal fibers; carbon fluoride; metal powders such as aluminum powder and nickel powder; conductive whiskers 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 mixtures of two or more, but are not necessarily limited to these. Preferably, the conductive material may also contain vapor-grown carbon fiber (VGCF).

[0068] The conductive material may typically be present in an amount of 1% to 5% by weight relative to the total weight of the positive electrode active material layer. Specifically, the content of the conductive material may be 1% or more by weight, 1.5% or more by weight, or 2% or more by weight, or 4% or less by weight, 4.5% or less by weight, or 5% or less by weight. If the content of the conductive material is too low (less than 1% by weight), it may be difficult to expect an improvement in electrical conductivity, or the electrochemical properties of the battery may deteriorate. If it is too high (more than 5% by weight), the amount of positive electrode active material will be relatively small, and the capacity and energy density may decrease. The method of incorporating the conductive material into the positive electrode is not significantly limited, and conventional methods known in the art, such as mixing with the positive electrode active material or coating, can be used.

[0069] Furthermore, the binder contains components that assist in the bonding of the positive electrode active material to conductive materials and to the current collector, such as styrene-butadiene rubber, acrylic 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, and polyacrylic. The binder may contain one or more selected from the group consisting of polynitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethylcellulose, hydroxypropylcellulose, cellulose acetate, cellulose 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 contain polytetrafluoroethylene (PTFE).

[0070] Furthermore, the binder may be present in an amount of 0.5% to 4% by weight based on the total weight of the positive electrode active material layer. Specifically, the binder content may be 0.5% or more by weight, 1% or more by weight, or 1.5% or more by weight, or 3% or less by weight, 3.5% or less by weight, or 4% or less by weight. If the binder content is less than 0.5% by weight, the adhesive strength between the positive electrode active material and the positive electrode current collector may decrease. If it exceeds 4% by weight, the adhesive strength will improve, but the content of the positive electrode active material will decrease accordingly, potentially reducing the battery capacity.

[0071] Furthermore, the positive electrode current collector supports the positive electrode active material layer and plays a role in transferring electrons between the external conductor and the positive electrode active material layer.

[0072] The positive electrode current collector is not particularly limited as long as it does not induce chemical changes in the all-solid-state battery and has high electronic conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., or aluminum-cadmium alloy may be used as the positive electrode current collector.

[0073] The positive electrode current collector may have a fine uneven surface or a three-dimensional porous structure to enhance the bonding force with the positive electrode active material layer. As a result, the positive electrode current collector may take various forms, such as film, sheet, foil, mesh, net, porous material, foam, nonwoven fabric, etc.

[0074] The positive electrode described above can be manufactured by conventional methods. Specifically, it can be manufactured by mixing a positive electrode active material, a conductive material, and a binder in an organic solvent to produce a composition for forming a positive electrode active material layer, which is then coated onto a positive electrode current collector and dried, and then compression-molded onto the current collector to selectively improve electrode density. In this case, it is preferable to use an organic solvent that can uniformly disperse the positive electrode active material, binder, and conductive material and evaporates easily. Specifically, examples include acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropyl alcohol, etc.

[0075] In the present invention, the negative electrode included in the all-solid-state battery includes a negative electrode active material layer, and the negative electrode active material layer may be formed on one surface of the negative electrode current collector.

[0076] The negative electrode active material is lithium (Li +This may include materials that can be reversibly intercalated or deintercalated, materials that can react with lithium ions to reversibly form lithium-containing compounds, lithium metals, or lithium alloys.

[0077] The aforementioned lithium ion (Li + The material that can reversibly insert or remove lithium ions (Li) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. + A substance that can reversibly form a lithium-containing compound by reacting with ) 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).

[0078] Preferably, the negative electrode active material may be lithium metal or lithium-indium alloy (Li-In), and specifically, it may be in the form of lithium metal or lithium in a thin film or lithium-indium alloy thin film or powder.

[0079] The negative electrode active material may be present in an amount of 40 to 80% by weight, based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40% or more by weight, 50% or more by weight, or 70% or less by weight, or 80% or less by weight. If the content of the negative electrode active material is less than 40% by weight, 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% by weight, the mass transfer resistance may increase.

[0080] Furthermore, the binder is as described above for the positive electrode active material layer.

[0081] Furthermore, the conductive material is as described above for the positive electrode active material layer.

[0082] Furthermore, the negative electrode current collector is not particularly limited as long as it does not induce chemical changes in the battery and is conductive. For example, the negative electrode current collector can be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy. Also, similar to the positive electrode current collector, the negative electrode current collector may be made of various forms such as films, sheets, foils, nets, porous materials, foams, nonwoven fabrics, etc., with fine irregularities formed on the surface.

[0083] The method for manufacturing the negative electrode is not particularly limited, and it can 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 industry. For example, methods such as crimping, coating, and vapor deposition can be used. Furthermore, the negative electrode of the present invention is also included in the case where a metallic lithium thin film is formed on a metal plate by initial charging after the battery has been assembled without a lithium thin film on the negative electrode current collector.

[0084] Manufacturing method for all-solid-state batteries The present invention also relates to a method for manufacturing all-solid-state batteries.

[0085] The method for manufacturing an all-solid-state battery according to the present invention includes the steps of (P1) positioning a mixture for forming a positive electrode active material layer on one surface of a solid electrolyte membrane and applying pressure to form a positive electrode on the one surface of the solid electrolyte membrane; and (P2) positioning a negative electrode on the other surface of the solid electrolyte membrane and applying pressure.

[0086] In step (P1), a mixture for forming a positive electrode active material layer is positioned on one surface of the solid electrolyte membrane, and a positive electrode can be formed on that surface of the solid electrolyte membrane by applying high temperature and pressure.

[0087] The mixture for forming the positive electrode active material layer may include a positive electrode active material, a conductive material, and a binder. The specific types and weights of these are as described above. Furthermore, a positive electrode can be manufactured by attaching a current collector after the positive electrode active material layer has been formed.

[0088] Furthermore, the pressurization step is used to bond the solid electrolyte membrane and the positive electrode, reducing interfacial resistance to achieve bonding, and may be performed at a pressure of 300 MPa to 500 MPa. The pressure of the high-temperature pressurization step may be 300 MPa or higher, 350 MPa or higher, or 400 MPa or higher, and may be 450 MPa or lower, 470 MPa or lower, or 500 MPa or lower. If the temperature and / or pressure of the high-temperature pressurization step is below the above range, the solid electrolyte membrane and the positive electrode may not be integrated, and if it exceeds the above range, the solid electrolyte membrane or the positive electrode may be deformed or damaged.

[0089] In step (P2), a negative electrode can be positioned on the other side of the solid electrolyte membrane and pressurized to manufacture an all-solid-state battery. The negative electrode is described above.

[0090] The pressure during pressurization may be between 40 MPa and 80 MPa. Specifically, the pressure during pressurization may be 40 MPa or more, 45 MPa or more, or 50 MPa or more, and may be 70 MPa or less, 75 MPa or less, or 80 MPa or less. If the pressure during pressurization is less than 40 MPa, the interfacial resistance between the negative electrode and the solid electrolyte membrane may increase, and if it exceeds 80 MPa, the solid electrolyte or negative electrode may deform or break.

[0091] Because all-solid-state batteries manufactured in this way contain a thin solid electrolyte membrane, the manufacturing cost can be reduced, and ion conductance and energy density can be improved.

[0092] Furthermore, since the solid electrolyte and the positive electrode are integrated through a high-temperature and high-pressure process, interfacial stability can be improved.

[0093] Battery module The present invention also relates to a battery module including the all-solid-state battery as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source.

[0094] Specific examples of the aforementioned devices include, but are not limited to, power tools powered by electric motors; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and power storage systems.

[0095] In one preferred embodiment of the present invention, the solid electrolyte membrane comprises a solid electrolyte and a fibrous binder. The solid electrolyte comprises one or more sulfide-based solid electrolytes and halogen-based solid electrolytes. The aforementioned sulfide-based solid electrolyte is represented by the following chemical formula 1, The aforementioned halogen-based solid electrolyte may be represented by the following chemical formula 2: [Chemical formula 1] L a1 M b1 P c1 S d1 A e1 In the above chemical formula 1, L is an element selected from Li, Na, and K, M is an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge, A represents I, Br, Cl, or F, a1 to e1 represent the composition ratio of each element, and a1:b1:c1:d1:e1 is 1 to 12:0 to 1:1:2 to 12:0 to 5. [Chemical formula 2] Li 6-3a M a Br bCl c In the above chemical 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。

[0096] In a preferred embodiment of the present invention, the sulfide-based solid electrolyte may include one or more selected from the group consisting of LiPSX (X=Cl, Br, or I)-based solid electrolytes, LiGePS-based solid electrolytes, and LiPS-based solid electrolytes.

[0097] In a preferred embodiment of the present invention, the LiPSX (X=Cl, Br, or I)-based solid electrolyte may be Li6PS5Cl.

[0098] In a preferred embodiment of the present invention, the halide-based solid electrolyte may include one or more selected from the group consisting of Li3YBr6, Li3YCl6, and Li3YBr2Cl4.

[0099] In one preferred embodiment of the present invention, the solid electrolyte may be present in an amount of 98% by weight or more, based on the total weight of the solid electrolyte membrane.

[0100] In a preferred embodiment of the present invention, the solid electrolyte may be particulate, and its particle size (D50) may be 10 nm to 10 μm.

[0101] In a preferred embodiment of the present invention, the fibrous binder may contain one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and copolymers containing the same.

[0102] In a preferred embodiment of the present invention, the fibrous binder may be present in an amount of 2% by weight or less, based on the total weight of the solid electrolyte membrane.

[0103] In a preferred embodiment of the present invention, the fibrous binder may be included in the solid electrolyte membrane in a dispersed state.

[0104] In a preferred embodiment of the present invention, the fibrous binder may form a cross-linked bonding structure in which the fibrous binders are intertwined with each other.

[0105] In one preferred embodiment of the present invention, the interface between the solid electrolyte and the fibrous binder may be bonded.

[0106] In a preferred embodiment of the present invention, the ionic conductivity of the solid electrolyte membrane may be 0.5 to 10 mS / cm.

[0107] In a preferred embodiment of the present invention, the tensile strength of the solid electrolyte membrane may be 45 to 1000 kPa.

[0108] In one preferred embodiment of the present invention, the solid electrolyte membrane may be solvent-free.

[0109] In one preferred embodiment of the present invention, the solid electrolyte may include a sulfide-based solid electrolyte represented by chemical formula 1.

[0110] In one preferred embodiment of the present invention, the solid electrolyte may include a halogenated solid electrolyte represented by chemical formula 2.

[0111] In a preferred embodiment of the present invention, the method for producing the solid electrolyte membrane includes the steps of mixing and pressurizing a solid electrolyte and a binder, and fibrousizing the binder in a solvent-free state, The solid electrolyte comprises one or more sulfide-based solid electrolytes and halogen-based solid electrolytes. The aforementioned sulfide-based solid electrolyte is represented by the following chemical formula 1, The aforementioned halogen-based solid electrolyte may be represented by the following chemical formula 2: [Chemical formula 1] L a1 M b1 P c1 S d1 A e1 In the above chemical formula 1, L is an element selected from Li, Na, and K, M is an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge, A represents I, Br, Cl, or F, a1 to e1 represent the composition ratio of each element, and a1:b1:c1:d1:e1 is 1 to 12:0 to 1:1:2 to 12:0 to 5. [Chemical formula 2] Li 6-3a M a Br b Cl c In the above chemical 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。

[0112] In a preferred embodiment of the present invention, the fibrous binder may form a cross-linked bonding structure in which the fibrous binders are intertwined with each other.

[0113] In a preferred embodiment of the present invention, the ionic conductivity of the solid electrolyte membrane may be 0.5 to 10 mS / cm.

[0114] In one preferred embodiment of the present invention, the all-solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte membrane interposed between the positive electrode and the negative electrode, The solid electrolyte membrane comprises a solid electrolyte and a fibrous binder. The solid electrolyte comprises one or more sulfide-based solid electrolytes and halogen-based solid electrolytes. The aforementioned sulfide-based solid electrolyte is represented by the following chemical formula 1, The aforementioned halogen-based solid electrolyte may be represented by the following chemical formula 2: [Chemical formula 1] L a1 M b1 P c1 S d1 A e1 In the above chemical formula 1, L is an element selected from Li, Na, and K, M is an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge, A represents I, Br, Cl, or F, a1 to e1 represent the composition ratio of each element, and a1:b1:c1:d1:e1 is 1 to 12:0 to 1:1:2 to 12:0 to 5. [Chemical formula 2] Li 6-3a M a Br b Cl c In the above chemical 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。

[0115] The following are preferred embodiments to aid in understanding the present invention. However, these embodiments are merely illustrative of the present invention, and it will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the present invention and the technical concept, and that such changes and modifications naturally fall within the scope of the attached claims.

[0116] In the following examples and comparative examples, solid electrolyte membranes were manufactured according to the compositions and processes described in Table 1 below.

[0117] [Table 1]

[0118] Example 1 A 300 μm thick solid electrolyte film was produced by mixing Li6PS5Cl powder, a sulfide-based solid electrolyte, with PTFE particles (polytetrafluoroethylene, Chemours) as a binder in a mortar and pestle, and then calendering the resulting mixture five times using a roll press.

[0119] Example 2 The procedure was carried out in the same manner as in Example 1, except that the content of the binder was set to 0.5% by weight of the total weight of the solid electrolyte membrane.

[0120] Example 3 The procedure was carried out in the same manner as in Example 1, except that the binder content was set to 2% by weight of the total weight of the solid electrolyte membrane.

[0121] Example 4 The procedure was carried out in the same manner as in Example 1, except that the content of the binder was set to 5% by weight of the total weight of the solid electrolyte membrane.

[0122] Comparative Example 1 The procedure was carried out in the same manner as in Example 1, except that a solid electrolyte membrane was manufactured in a wet process using a solvent.

[0123] For the aforementioned wet process, a xylene solvent, which is stable in sulfide-based solid electrolytes, was used as the solvent.

[0124] A solution was prepared by dissolving PTFE particles, which act as a binder, in xylene solvent at a concentration of 5% by weight. This solution was mixed with Li6PS5Cl powder, a sulfide-based solid electrolyte, and the resulting mixture was coated onto a PET (polyethylene terephthalate) release film using a doctor blade. The film was then vacuum-dried at 100°C for 12 hours. The binder was adjusted to account for 0.2% by weight of the total weight of the solid electrolyte film.

[0125] Comparative Example 2 A solid electrolyte membrane was manufactured using the same method as the wet process in Comparative Example 1, except that NBR (nitrile-butadiene rubber) was used instead of PTFE as the binder. NBR is a binder commonly used in wet processes and is easily soluble in solvents.

[0126] Comparative Example 3 A solid electrolyte membrane was manufactured in the same manner as in Comparative Example 2, except that the NBR content as a binder was set to 5% by weight.

[0127] Experimental Example 1: Internal Structure of a Solid Electrolyte Membrane An experiment was conducted to confirm the internal structure of the solid electrolyte membrane produced in Example 1.

[0128] Figure 2 is a scanning electron microscope (SEM, FEI Apreo SEM) image of the solid electrolyte membrane fabricated in Example 1.

[0129] Referring to Figure 2, we can see the intertwined cross-linking structure inside the solid electrolyte membrane of Example 1. It can be seen that this structure was formed when the binder was fibrousized during the dry process, and the fibrous binder then intertwined with each other.

[0130] Experimental Example 2: Measurement of Ionic Conductivity and Tensile Strength of Solid Electrolyte Membranes To confirm the correlation between binder content and the ionic conductivity characteristics of the solid electrolyte, the ionic conductivity of the solid electrolyte membrane was measured.

[0131] (1) Measurement of ionic conductivity To measure the ionic conductivity of a solid electrolyte membrane, the membrane was placed in a 10 mm diameter polyether ether ketone (PEEK) holder, and a titanium rod was used as a blocking electrode to measure the ionic conductivity.

[0132] Using an electrochemical impedance spectrometer (EIS, VM3, Bio Logic Science Instrument), the resistance was measured at 25°C with an amplitude of 10mV and a scan range from 1Hz to 0.1MHz. The ionic conductivity of the solid electrolyte membrane was then calculated using Equation 1 below.

[0133] [Formula 1]

number

[0134] In the above formula 1, σ i R is the ionic conductivity (mS / cm) of the solid electrolyte membrane, R is the resistance (Ω) of the solid electrolyte membrane measured by the electrochemical impedance spectrometer, L is the thickness (μm) of the solid electrolyte membrane, and A is the area (cm²) of the solid electrolyte membrane. 2 ) means.

[0135] (2) Measurement of tensile strength The solid electrolyte membrane was cut into 10mm x 50mm pieces. To minimize damage to the solid electrolyte membrane from the gripping tool during measurement, tape was attached to both ends of the sample, and then the tensile strength was measured using a UTM (Universal Testing Machine, MARK-10, M5-05) equipped with this tool.

[0136] (3) Correlation between binder content, ionic conductivity, and tensile strength X, which represents the correlation between binder content, ionic conductivity, and tensile strength, is calculated using the following formula 2. When X is between 170 and 1000, it is determined to be a solid electrolyte membrane with excellent ionic conductivity and tensile strength. [Formula 2] X = (b*c) / a In the above formula 2, a is the binder content contained in the solid electrolyte membrane, b is the ionic conductivity of the solid electrolyte membrane, and c is the tensile strength of the solid electrolyte membrane.

[0137] [Table 2]

[0138] Figure 3 is a graph showing the correlation between the binder content, ionic conductivity, and tensile strength in a solid electrolyte membrane according to one embodiment of the present invention.

[0139] Referring to Figure 3, we confirmed that binder content and ionic conductivity are inversely proportional, and binder content and tensile strength are proportional.

[0140] Example 1 and Comparative Example 1 describe the manufacturing process of solid electrolyte membranes produced using a dry process and a wet process, respectively. In the wet process of Comparative Example 1, the PTFE was not fiberized, and therefore a cross-linked bonding structure could not be formed. As a result, the strength was weak, and it was not possible to manufacture it as a membrane.

[0141] Furthermore, in Comparative Example 2, the solid electrolyte membrane was manufactured using a wet process, such as a conventional slurry coating process. Because the content of NBR, a binder commonly used in wet processes, was low, it lacked the strength to function as a solid electrolyte membrane and could not be manufactured in membrane form. In Comparative Example 3, despite having a high content of NBR, the binder, it was manufactured using a wet process, and it was confirmed that its strength and ionic conductivity were lower compared to solid electrolyte membranes manufactured using a dry process.

[0142] As stated above, the present invention is not limited by the limited embodiments and drawings, and it goes without saying that various modifications and variations are possible by persons with ordinary skill in the art to which the present invention pertains, within the equivalent scope of the technical concept of the present invention and the claims described below. [Explanation of Symbols]

[0143] 1: Solid electrolyte membrane 10: Solid electrolytes (sulfide-based and / or halide-based) 20: Fibrous binder

Claims

1. A solid electrolyte membrane comprising a solid electrolyte and a fibrous binder. The solid electrolyte comprises one or more selected from the group consisting of sulfide-based solid electrolytes and halide-based solid electrolytes. The solid electrolyte is 95% by weight or more and 98% by weight or less, based on the total weight of the solid electrolyte membrane. The fibrous binder comprises one or more selected from the group consisting of polytetrafluoroethylene (PTFE) and copolymers containing the same. The fibrous binder is present in an amount of 2% by weight or more and 5% by weight or less of the total weight of the solid electrolyte membrane.

2. The sulfide-based solid electrolyte is represented by the following chemical formula 1, the solid electrolyte membrane according to claim 1: [Chemical formula 1] L ａ１ M ｂ１ P ｃ１ S ｄ１ A ｅ１ In the above chemical formula 1, L is an element selected from Li, Na, and K, M is an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge, A represents I, Br, Cl, or F, a1, b1, c1, d1, and e1 represent the composition ratio of each element, and a1:b1:c1:d1:e1 is 1 to 12:0 to 1:1:2 to 12:0 to 5.

3. The solid electrolyte membrane according to claim 1, wherein the halide-based solid electrolyte is represented by the following chemical formula 2: [Chemical formula 2] Li ６－３ａ M ａ Br ｂ Cl ｃ In the above chemical formula 2, M is a metal other than Li, a is 0 < a < 2, b is 0 ≤ b ≤ 6, c is 0 ≤ c ≤ 6, and b + c = 6.

4. The solid electrolyte membrane according to claim 1, wherein the fibrous binder is contained in the solid electrolyte membrane in a dispersed state.

5. The solid electrolyte membrane according to claim 1, wherein the interface between the solid electrolyte and the fibrous binder is bonded.

6. The solid electrolyte membrane according to claim 1, wherein the ionic conductivity of the solid electrolyte membrane is 0.5 to 10 mS / cm.

7. The solid electrolyte membrane according to claim 1, wherein the tensile strength of the solid electrolyte membrane is 45 to 1000 kPa.

8. A method for producing a solid electrolyte membrane according to Claim 1, The solid electrolyte membrane is manufactured in a solvent-free manner, and the method for manufacturing a solid electrolyte membrane.

9. A solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte membrane interposed between them according to any one of claims 1 to 7.

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