Sulfide-based solid electrolyte and all-solid-state battery comprising same

Abstract

The present invention relates to a sulfide-based solid electrolyte and an all-solid-state battery comprising same. More specifically, by adding various heterogeneous elements into the sulfide-based solid electrolyte to give rise to structural disorder while maintaining the crystal structure of the sulfide-based solid electrolyte, ionic conductivity can be improved by enhancing lithium ion mobility.

Description

Sulfide-based solid electrolyte and all-solid-state battery containing the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0057402, dated April 30, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a sulfide-based solid electrolyte and an all-solid-state battery including the same.

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

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

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

[0008] However, in all-solid-state batteries, the solid electrolyte is applied in a state of small particle size, which increases the interface and increases the resistance, which ultimately reduces the performance, lifespan, and stability of the all-solid-state battery, and may deteriorate the cell performance.

[0009] The deterioration of cell performance due to such increase in interfacial resistance can be offset by increasing the ionic conductivity of the solid electrolyte.

[0010] Therefore, development of a solid electrolyte with high ionic conductivity as a solid electrolyte for all-solid-state batteries is necessary.

[0011] [Prior Art Literature]

[0012] (Patent Document 1) Korean Patent Publication No. 2021-0101061

[0013] The inventors of the present invention have conducted various studies to solve the above problems and have confirmed that when various heterogeneous elements such as metallic elements germanium (Ge), silicon (Si) and antimony (Sb) and halide element iodine (I) are introduced into a sulfide-based solid electrolyte, the crystal structure of the sulfide-based solid electrolyte is maintained while the disorder of the internal structure increases, thereby improving the mobility of lithium ions and enhancing ionic conductivity.

[0014] Accordingly, the purpose of the present invention is to provide a sulfide-based solid electrolyte with improved ionic conductivity.

[0015] In addition, another object of the present invention is to provide an all-solid-state battery including a sulfide-based solid electrolyte having improved ionic conductivity.

[0016] In order to achieve the above purpose, the present invention provides a sulfide-based solid electrolyte comprising a metal element and a halide element,

[0017] The above metal elements include germanium (Ge), silicon (Si) and antimony (Sb),

[0018] The above halide element provides a sulfide-based solid electrolyte including iodine (I):

[0019] In one embodiment of the present invention, the sulfide-based solid electrolyte may be represented by the following chemical formula 1:

[0020] <Chemical Formula 1>

[0021] Li 8-α-z Ge x Si y Sb z S 6-α I α

[0022] In the above chemical formula 1, 0.1 < x < 0.4, 0.2 < y < 0.5, 0.2 < z < 0.5, 0.8 < α < 1.3.

[0023] In one embodiment of the present invention, the halide element may further include at least one selected from the group consisting of bromine (Br) and chloride (Cl).

[0024] In one embodiment of the present invention, the sulfide-based solid electrolyte may be represented by the following chemical formula 2:

[0025] <Chemical Formula 2>

[0026] Li 8-α-z Ge x Si y Sb z S 6-α I α Br β Cl γ

[0027] In the above chemical formula 2, 0.1 < x < 0.4, 0.2 < y < 0.5, 0.2 < z < 0.5, 0.8 < α + β + γ < 1.3, and the cases where α = 0 and β = γ = 0 are excluded.

[0028] In one embodiment of the present invention, the sulfide-based solid electrolyte may be phosphorus-free.

[0029] In one embodiment of the present invention, the ionic conductivity of the sulfide-based solid electrolyte may be 4 to 8 mS / cm.

[0030] In one embodiment of the present invention, the sulfide-based solid electrolyte may be in the form of a sulfide-based solid electrolyte membrane.

[0031]

[0032] The present invention also relates to an all-solid-state battery comprising a positive electrode, a negative electrode, and the sulfide-based solid electrolyte interposed therebetween.

[0033] In one embodiment of the present invention, the negative electrode may be a lithium negative electrode including lithium metal.

[0034] According to the present invention, by introducing various heterogeneous elements into a sulfide-based solid electrolyte, the crystal structure of the sulfide-based solid electrolyte is maintained while the disorder of the internal structure increases, thereby improving the mobility of lithium ions and enhancing the ion conductivity.

[0035] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0036] The terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0037]

[0038] Sulfide-based solid electrolyte

[0039] The present invention relates to a sulfide-based solid electrolyte.

[0040]

[0041] The sulfide-based solid electrolyte according to the present invention is a sulfide-based solid electrolyte including a metal element and a halide-based element, wherein the metal element includes germanium (Ge), silicon (Si), and antimony (Sb), and the halide-based element includes iodine (I). Due to the metal element and the halide-based element, disorder in the sulfide-based solid electrolyte increases, allowing lithium ions to move smoothly, and thus improving the ionic conductivity of the sulfide-based solid electrolyte.

[0042] In addition, by including the above halide element, the disorder of the structure within the sulfide-based solid electrolyte can be further improved.

[0043]

[0044] In general, the crystal structure of a sulfide-based solid electrolyte is a face-centered cubic lattice (FCC) structure, so that lithium ions are trapped within sulfur atom octahedra during movement. However, if some of the materials are replaced with a different material, the strength of electrostatic attraction changes, changing the arrangement of atoms within the structure, thereby lowering the activation energy and securing a new path for lithium ion movement, thereby improving ionic conductivity. Therefore, in the present invention, by introducing the metal element and the halide element as a different material to the crystal structure of a conventional sulfide-based solid electrolyte, ionic conductivity can be further improved.

[0045] For example, when introducing three types of metals as heterogeneous substances into the crystal structure of a conventional sulfide-based solid electrolyte, disorder increases and the movement of Li can be facilitated, thereby improving ionic conductivity. Some of the Sb with an oxidation number of +5 is replaced with Ge and Si, which are metals with a oxidation number of +4, and Li is added to compensate for the oxidation number to maintain the electrical neutrality of the molecule. + is added. At this time, Li +For example, it can be added in the form of Li2S. In this case, the ionic conductivity is improved due to the sufficient Li content, and the movement of lithium ions is improved due to the vacancy in the structure created by partial substitution of elements with different oxidation numbers, thereby improving the ionic conductivity.

[0046] If even one of the three metals mentioned above is not included, the degree of increase in disorder within the structure may be minimal, resulting in minimal improvement in ionic conductivity. Furthermore, Sb is a toxic substance. By including a small amount of Sb along with two other metals, ionic conductivity can be improved while minimizing the toxicity associated with using small amounts of Sb.

[0047]

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

[0049] <Chemical Formula 1>

[0050] Li 8-α-z Ge x Si y Sb z S 6-α I α

[0051] In the above chemical formula 1, 0.1 < x < 0.4, 0.2 < y < 0.5, 0.2 < z < 0.5, 0.8 < α < 1.3.

[0052] The above α may be greater than 0.8, 0.85 or more, 0.9 or more, 0.95 or more, 1 or more, 1.1 or more, or 1.15 or more, and may be less than 1.3 or 1.25 or less. If the above α is 0.8 or less, the crystal structure may not be properly formed, the material of the targeted composition may not be synthesized, and impurities may remain, and if the above α is 1.3 or more, the element to be substituted may not be substituted and may remain as a raw material.

[0053]

[0054] In one embodiment of the present invention, the halide element may further include at least one selected from the group consisting of bromine (Br) and chloride (Cl).

[0055] When at least one selected from the group consisting of bromine (Br) and chloride (Cl) is further included together with iodine (I) as the above halide element, disorder in the sulfide-based solid electrolyte can be further increased.

[0056]

[0057] In one embodiment of the present invention, the sulfide-based solid electrolyte may be represented by the following chemical formula 2:

[0058] <Chemical Formula 2>

[0059] Li 8-α-z Ge x Si y Sb z S 6-α I α Br β Cl γ

[0060] In the above chemical formula 2, 0.1 < x < 0.4, 0.2 < y < 0.5, 0.2 < z < 0.5, 0.8 < α + β + γ < 1.3, and the cases where α = 0 and β = γ = 0 are excluded.

[0061] The above α + β + γ may be greater than 0.8, 0.85 or more, 0.9 or more, 0.95 or more, 1 or more, 1.1 or more, or 1.15 or more, and may be less than 1.3 or 1.25 or less. If the above α + β + γ is 0.8 or less, the crystal structure may not be properly formed, the material of the target composition may not be synthesized, and impurities may remain, and if it is 1.3 or more, the element to be substituted may not be substituted and may remain as a raw material.

[0062]

[0063] In one embodiment of the present invention, the sulfide-based solid electrolyte may be phosphorus-free.

[0064] The combination of phosphorus and sulfur is identical to the components of early matches. Early matches are easy to ignite, but pose a high risk of ignition during storage and transportation. Following this same principle, phosphorus-free sulfide-based solid electrolytes, which do not contain phosphorus, can suppress the risk of ignition and explosion that may occur during the synthesis process. The synthesis process, in this case, may refer to a precursor milling process, such as that performed during the manufacture of sulfide-based solid electrolytes.

[0065]

[0066] In one embodiment of the present invention, the ionic conductivity of the sulfide-based solid electrolyte may be 4 to 8 mS / cm.

[0067] The above sulfide-based solid electrolyte may contain the metal element and halide element, which may cause disorder within the structure. This may facilitate the movement of lithium ions and increase the element solid solution ratio, thereby improving ionic conductivity.

[0068] Specifically, the ionic conductivity of the sulfide-based solid electrolyte may be 4 mS / cm or more, 4.5 mS / cm or more, 5 mS / cm or more, 5.5 mS / cm or more, or 6 mS / cm or more, and may be 8 mS / cm or less, 7.5 mS / cm or less, 7 mS / cm or less, or 6.5 mS / cm or less.

[0069]

[0070] In one embodiment of the present invention, the sulfide-based solid electrolyte may be in the form of a solid electrolyte membrane.

[0071] Additionally, the sulfide-based solid electrolyte may be in the form of particles. In this case, the sulfide-based solid electrolyte can also be applied to the positive or negative electrode. For example, the sulfide-based solid electrolyte in the form of particles can be applied to an electrode layer, such as the positive or negative electrode layer.

[0072]

[0073] Method for manufacturing sulfide-based solid electrolyte

[0074] The present invention also relates to a method for producing a sulfide-based solid electrolyte.

[0075] The method for manufacturing a sulfide-based solid electrolyte according to the present invention comprises the steps of (S1) mixing raw materials; and (S2) heat-treating the mixture obtained in step (S1) to synthesize a sulfide-based solid electrolyte. This may also be referred to as a solid-state synthesis method.

[0076]

[0077] Hereinafter, the method for manufacturing a sulfide-based solid electrolyte according to the present invention will be described in more detail step by step.

[0078]

[0079] In one embodiment of the present invention, in the step (S1), raw materials can be mixed.

[0080] The above raw material may refer to a precursor of each element included in the sulfide-based solid electrolyte. The raw material is not particularly limited as long as it is a material commonly used in the art as a precursor of each element. For example, the raw material forming the sulfide-based solid electrolyte may include lithium sulfide (Li2S), germanium sulfide (GeS2), silicon (Si), antimony (Sb), and lithium iodide (LiI). For example, 2.5 to 5 mol of Li2S, more than 0 mol of GeS2 but less than 1 mol, more than 0 mol of Si but less than 1 mol, more than 0 mol of Sb but less than 1 mol, more than 0 mol of S but less than 2 mol, and more than 0 mol of LiI but less than 2 mol may be used. In addition, LiBr and LiCl may be used as raw materials for Br and Cl. The above LiBr may be used in an amount of more than 0 mol and less than or equal to 0.6 mol, and the above LiCl may be used in an amount of more than 0 mol and less than or equal to 0.3 mol. Specifically, the amount of LiBr used may be more than 0 mol, more than or equal to 0.05 mol, or more than or equal to 0.1 mol, and may be less than or equal to 0.3 mol, less than or equal to 0.25 mol, or less than or equal to 0.2 mol. The amount of LiCl used may be more than 0 mol, more than or equal to 0.02 mol, more than or equal to 0.04 mol, or more than or equal to 0.05 mol, and may be less than or equal to 0.3 mol, less than or equal to 0.2 mol, or less than or equal to 0.1 mol.

[0081]

[0082] In addition, the method for the above mixing is not particularly limited as long as it is a method that can be performed in the art to mix raw materials. For example, the mixing method may be milling, such as hand milling or ball milling. The ball milling may be vibratory ball milling and may be performed at 20 to 50 Hz for 1 to 30 minutes.

[0083]

[0084] In one embodiment of the present invention, in the step (S2), the mixture obtained in the step (S1) can be heat-treated to perform solid-state synthesis.

[0085] The above heat treatment can be performed under conditions of a temperature of 300°C to 600°C and a time of 4 to 48 hours under an inert atmosphere. Specifically, the heat treatment temperature can be 300°C or higher, 350°C or higher, or 400°C or higher, and 600°C or lower, 550°C or lower, or 500°C or lower. In addition, the heat treatment time can be 4 hours or higher, 6 hours or higher, 8 hours or higher, 10 hours or higher, or 12 hours or higher, and 48 hours or lower, 45 hours or lower, 40 hours or lower, 35 hours or lower, 30 hours or lower, 25 hours or lower, 20 hours or lower, or 15 hours or lower. The inert atmosphere can mean a nitrogen, helium, argon, or carbon dioxide atmosphere. In addition, the heat treatment can be performed by increasing the temperature, and the temperature increasing rate can be 1 to 10°C / min. Specifically, the heating rate may be 1 ℃ / min or more, 2 ℃ / min or more, 3 ℃ / min or more, or 4 ℃ / min or more, and may be 10 ℃ / min or less, 9 ℃ / min or less, 8 ℃ / min or less, 7 ℃ / min or less, or 6 ℃ / min or less.

[0086] In addition, a sulfide-based solid electrolyte according to the present invention can be obtained through the steps (S1) and (S2), and the manufacturing process including the steps (S1) and (S2) can be performed in a glove box that is not exposed to moisture and oxygen.

[0087]

[0088] All-solid-state batteries

[0089] The present invention also relates to an all-solid-state battery comprising the above sulfide-based solid electrolyte.

[0090] An all-solid-state battery according to the present invention comprises: a sulfide-based solid electrolyte membrane including the sulfide-based solid electrolyte; an anode formed on one surface of the sulfide-based solid electrolyte membrane; and an anode formed on the other surface of the sulfide-based solid electrolyte membrane.

[0091]

[0092] In one embodiment of the present invention, the positive electrode may include a positive electrode active material, a conductive material, and a binder.

[0093]

[0094] 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.

[0095] The above positive electrode active material layer includes a positive electrode active material, a conductive material, and a binder.

[0096] In addition, the positive electrode active material is not particularly limited as long as it is a material capable of reversibly absorbing and releasing lithium ions, and examples thereof include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and Li[Ni x Co y Mn z M v ]O2 (wherein M is one or two or more elements selected from the group consisting of Al, Ga, and In; 0.3≤x<1.0, 0≤y, z≤0.5, 0≤v≤0.1, x+y+z+v=1), Li(Li a M b-a-b' M' b' )O 2-c A c(In the above formula, 0≤a≤0.2, 0.6≤b≤1, 0≤b'≤0.2, 0≤c≤0.2; M includes at least one selected from the group consisting of Mn and Ni, Co, Fe, Cr, V, Cu, Zn and Ti; M' is at least one selected from the group consisting of Al, Mg and B, and A is at least one selected from the group consisting of P, F, S and N.) layered compounds or compounds substituted with one or more transition metals; chemical formula Li 1+y Mn 2-y Lithium manganese oxides such as O4 (where y is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-y Ni-site type lithium nickel oxide represented by MyO2 (wherein, M=Co, Mn, Al, Cu, Fe, Mg, B or Ga, and y is 0.01 to 0.3); chemical formula LiMn 2-y M y Lithium manganese composite oxides represented by O2 (wherein M is Co, Ni, Fe, Cr, Zn or Ta, and y is 0.01 to 0.1) or Li2Mn3MO8 (wherein M is Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of Li in the chemical formula is replaced by an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, etc., but are not limited thereto.

[0097] In addition, the positive electrode active material may be included in an amount of 60 to 80 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 60 wt%, 65 wt% or more, or 68 wt% or more, and may be 72 wt% or less, 75 wt% or less, or 80 wt% or less. If the content of the positive electrode active material is less than 60 wt%, battery performance may deteriorate, and if it is more than 80 wt%, mass transfer resistance may increase.

[0098]

[0099] In addition, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery, does not cause chemical changes in the battery, and has excellent electrical conductivity. Representative examples thereof include graphite or conductive carbon, and examples thereof include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black, and summer black; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers such as carbon fiber and metal fiber; fluorinated carbon; metal powder such as aluminum powder and nickel powder; conductive whiskey such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives; which may be used alone or in combination of two or more thereof, but are not necessarily limited thereto. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0100] The conductive material may typically be included in an amount of 1 wt% to 5 wt% based on the total weight of the positive electrode active material layer, and specifically, the content of the conductive material may be 1 wt% or more, 1.5 wt% or more, or 2 wt% or more, and 4 wt% or less, 4.5 wt% or less, or 5 wt% or less. If the content of the conductive material is too low, such as less than 1 wt%, it may be difficult to expect an effect of improving electrical conductivity or the electrochemical characteristics of the battery may deteriorate, and if it exceeds 5 wt%, the amount of positive electrode active material may be relatively small, which may lower the capacity and energy density. The method of including the conductive material in the positive electrode is not particularly limited, and conventional methods known in the art, such as mixing or coating with the positive electrode active material, may be used.

[0101]

[0102] In addition, the binder is a component that assists in the bonding of the positive electrode active material and the conductive material and the bonding to the current collector, and includes styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenol resin, epoxy resin, carboxymethylcellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate It may include at least one selected from the group consisting of butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0103] In addition, the binder may be included in an amount of 0.5 wt% to 4 wt% based on the total weight of the positive electrode active material layer, and specifically, the content of the binder may be 0.5 wt% or more, 1 wt% or more, or 1.5 wt% or more, and 3 wt% or less, 3.5 wt% or less, or 4 wt% or less. If the content of the binder is less than 0.5 wt%, the adhesive strength between the positive electrode active material and the positive electrode current collector may be reduced, and if it exceeds 4 wt%, the adhesive strength may be improved, but the content of the positive electrode active material may be reduced, which may lower the battery capacity.

[0104]

[0105] In addition, the positive electrode current collector supports the positive electrode active material layer and serves to transfer electrons between the external conductor and the positive electrode active material layer.

[0106] The positive electrode current collector is not particularly limited as long as it has high electronic conductivity without causing chemical changes in the all-solid-state battery. For example, the positive electrode current collector may be copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., or an aluminum-cadmium alloy.

[0107] The positive electrode current collector may have a finely irregular structure on its surface or may employ a three-dimensional porous structure to strengthen the bonding strength with the positive electrode active material layer. Accordingly, the positive electrode current collector may include various forms such as a film, sheet, foil, mesh, net, porous body, foam, or non-woven fabric.

[0108] The positive electrode as described above can be manufactured according to a conventional method, and specifically, a composition for forming a positive electrode active material layer prepared by mixing a positive electrode active material, a conductive agent, and a binder in an organic solvent phase is applied and dried on a positive electrode current collector, and optionally, to improve electrode density, it can be manufactured by compression molding the positive electrode current collector. At this time, it is preferable to use an organic solvent that can uniformly disperse the positive electrode active material, binder, and conductive agent and is easily evaporated. Specifically, examples thereof include acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropyl alcohol, and the like.

[0109]

[0110] 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.

[0111] The above negative active material is lithium (Li + ) can be reversibly intercalated or deintercalated, a material that can react with lithium ions to form a reversibly lithium-containing compound, or a lithium metal or a lithium alloy.

[0112] The above lithium ion (Li + ) can be reversibly inserted or de-inserted, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The lithium ion (Li +) can be, for example, tin oxide, titanium nitrate or silicon. The lithium alloy can be, for example, an alloy of lithium (Li) and a metal selected from the group consisting of indium (In), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al) and tin (Sn).

[0113] Preferably, the negative electrode active material may be lithium metal or a lithium-indium alloy (Li-In), and specifically, may be in the form of lithium metal or lithium and a thin film or a lithium-indium alloy thin film or powder.

[0114] The negative electrode active material may be included in an amount of 40 to 80 wt% based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40 wt% or more or 50 wt% or more, and 70 wt% or less or 80 wt% or less. If the content of the negative electrode active material is less than 40 wt%, the connectivity between the wet negative electrode active material layer and the dry negative electrode active material layer may be insufficient, and if it exceeds 80 wt%, the material transfer resistance may increase.

[0115] In addition, the binder is as described above in the positive electrode active material layer.

[0116] In addition, the above-described conductive material is as described above in the positive electrode active material layer.

[0117] In addition, the negative electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery. For example, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. In addition, the negative electrode current collector, like the positive electrode current collector, may be made of various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc. having fine irregularities formed on the surface.

[0118] The method for manufacturing the above negative electrode is not particularly limited, and can be manufactured by forming a negative electrode active material layer on the negative electrode current collector using a method for forming a layer or film commonly used in the art. For example, methods such as compression, coating, and deposition can be used. In addition, a case in which a battery is assembled on the negative electrode current collector without a lithium thin film and then a metallic lithium thin film is formed on the metal plate through initial charging is also included in the negative electrode of the present invention.

[0119]

[0120] battery module

[0121] 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.

[0122] At this time, specific examples of the device include, but are not limited to, a power tool that is powered by an electric motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), etc.; an electric two-wheeled vehicle including an electric bicycle (E-bike) and an electric scooter (E-scooter); an electric golf cart; and a power storage system.

[0123] Hereinafter, preferred examples are presented to help understand the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it is also natural that such changes and modifications fall within the scope of the appended patent claims.

[0124]

[0125] In the following examples and comparative examples, a sulfide-based solid electrolyte was manufactured according to the composition shown in Table 1 below.

[0126]

[0127] The following examples and comparative examples are sulfide-based solid electrolytes containing metal elements and halide elements. Examples 1 to 6 are sulfide-based solid electrolytes containing three metal elements and I as a halide element, and having changed I contents. Example 7 is a sulfide-based solid electrolyte containing three metal elements and I and Br as halide elements. Examples 8 and 9 are sulfide-based solid electrolytes containing three metal elements and I, Br, and Cl as halide elements. Comparative Examples 1 to 3 are sulfide-based solid electrolytes containing two metal elements.

[0128]

[0129] Li2SGeS2SiSbSLiILiBrLiClExample 12.91250.250.3750.3751.68750.900Example 22.81250.250.3750.3751.6875100Example 32.71250.250.3750.3751.68751.100Example 42.66250.250.3750.3751.68751.1500Example 52.61250.250.3750.3751.68751.200Example 62.56250.250.3750.3751.68751.2500Example 72.66250.250.3750.3751.68751.030.120Example 82.680.240.380.381.711.040.050.04Example 92.66260.250.3750.3751.68751.030.10.02Comparative Example 12.80.330.6701.341.200Comparative Example 22.4650.3300.671.6751.200Comparative Example 32.5500.50.52.251.200

[0130]

[0131] Example 1

[0132] After mixing the raw materials in a glove box by vibration ball milling (40 Hz, 5 min), solid-state synthesis was performed by heat treatment at 450°C for 12 hours at a heating rate of 5°C / min in an Ar atmosphere, and a sulfide-based solid electrolyte (Li) containing Ge, Si, and Sb was prepared. 6.625 Ge 0.25 Si 0.375 Sb 0.375 S5I) was manufactured. The raw materials used were 2.9125 mol of Li2S (Sigma Aldrich), 0.25 mol of GeS2 (Kojundo), 0.375 mol of Si (Sigma Aldrich), 0.375 mol of Sb (Sigma Aldrich), 1.6875 mol of S (Sigma Aldrich), and 0.9 mol of LiI (Alfa aesar).

[0133]

[0134] Example 2

[0135] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that 2.8125 mol of Li2S (Sigma Aldrich) and 1 mol of LiI (Alfa aesar) were used.

[0136]

[0137] Example 3

[0138] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that 2.7125 mol of Li2S (Sigma Aldrich) and 1.1 mol of LiI (Alfa aesar) were used.

[0139]

[0140] Example 4

[0141] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that 2.6625 mol of Li2S (Sigma Aldrich) and 1.15 mol of LiI (Alfa aesar) were used.

[0142]

[0143] Example 5

[0144] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that 2.6125 mol of Li2S (Sigma Aldrich) and 1.2 mol of LiI (Alfa aesar) were used.

[0145]

[0146] Example 6

[0147] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that 2.5625 mol of Li2S (Sigma Aldrich) and 1.25 mol of LiI (Alfa aesar) were used.

[0148]

[0149] Example 7

[0150] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that 2.6625 mol of Li2S (Sigma Aldrich), 1.03 mol of LiI (Alfa aesar), and 0.12 mol of LiBr (Sigma Aldrich) were used.

[0151]

[0152] Example 8

[0153] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that 2.6625 mol of Li2S (Sigma Aldrich), 1.03 mol of LiI (Alfa aesar), 0.05 mol of LiBr (Sigma Aldrich), and 0.04 mol of LiCl (Sigma Aldrich) were used.

[0154]

[0155] Example 9

[0156] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that 2.6625 mol of Li2S (Sigma Aldrich), 1.03 mol of LiI (Alfa aesar), 0.1 mol of LiBr (Sigma Aldrich), and 0.02 mol of LiCl (Sigma Aldrich) were used.

[0157]

[0158] Comparative Example 1

[0159] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that Sb was not included among the metals.

[0160] At this time, 2.8 mol of Li2S (Sigma Aldrich), 0.33 mol of GeS2 (Kojundo), 0.67 mol of Si (Sigma Aldrich), 1.34 mol of S (Sigma Aldrich), and 1.2 mol of LiI (Alfa aesar) were used as raw materials.

[0161]

[0162] Comparative Example 2

[0163] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that Si was not included among the metals.

[0164] At this time, 2.465 mol of Li2S (Sigma Aldrich), 0.33 mol of GeS2 (Kojundo), 0.67 mol of Sb (Sigma Aldrich), 1.675 mol of S (Sigma Aldrich), and 1.2 mol of LiI (Alfa aesar) were used as raw materials.

[0165]

[0166] Comparative Example 3

[0167] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1, except that Ge was not included among the metals.

[0168] At this time, 2.55 mol of Li2S (Sigma Aldrich), 0.5 mol of Si (Sigma Aldrich), 0.5 mol of Sb (Sigma Aldrich), 2.25 mol of S (Sigma Aldrich), and 1.2 mol of LiI (Alfa aesar) were used as raw materials.

[0169]

[0170] Experimental Example 1: Ionic Conductivity Measurement

[0171] In order to measure the ionic conductivity of the sulfide-based solid electrolyte manufactured in the examples and comparative examples, electrochemical impedance spectroscopy (EIS) analysis was performed.

[0172] For EIS analysis, an electrode cell was manufactured. The electrode cell was manufactured by placing 200 mg of the above sulfide-based solid electrolyte into an electrode with a diameter of 13 mm and pressurizing it at a pressure of 360 MPa.

[0173] The resistance was measured using an electrochemical impedance spectrometer (EIS, VMP300Bio Logic) at 25°C under AC 0.1 V and a frequency from 1 Hz to 0.1 MHz, and the ionic conductivity of the sulfide-based solid electrolyte was calculated using Equation 1 below.

[0174]

[0175] [Formula 1]

[0176]

[0177]

[0178] In the above equation 1, σ i is the ionic conductivity (mS / cm) of the sulfide-based solid electrolyte, R is the resistance (Ω) of the sulfide-based solid electrolyte measured by the electrochemical impedance spectrometer, L is the thickness (㎛) of the sulfide-based solid electrolyte, and A is the area (cm) of the sulfide-based solid electrolyte. 2 ) means.

[0179]

[0180] Table 2 below shows the composition and measured ionic conductivity of the sulfide-based solid electrolytes manufactured in the examples and comparative examples.

[0181]

[0182] LiGeSiSbSIBrCl Ionic Conductivity (mS / cm) Example 16.7 250.25 0.375 0.375 5.10.9--4.63 Example 26.6 250.25 0.375 0.375 5.10.9--4.48 Example 36.5 250.25 0.375 0.375 4.9 1.1--6.04 Example 46.4 750.25 0.375 0.375 4.8 5 1.15--6.24 Example 56.4 250.25 0.375 0.375 4.8 1.2--6.56 Example 66.375 0.25 0.375 0.375 4.75 1.25--5.84 Example 76.4750.250.3750.3754.851.030.12-6.34Example 86.490.240.380.384.871.040.050.046.3Example 96.4750.250.3750.3754.851.030.10.026.24Comparative Example 16.80.40.604.81.2--0.001Comparative Example 26.20.400.64.81.2--0.46Comparative Example 36.300.50.54.81.2--2.19

[0183]

[0184] Referring to Table 2 above, it was confirmed that the ionic conductivity of the example including three types of metals including Ge, Si, and Sb and halide elements was excellent.

[0185] When only I is included as a halide element, as shown in Examples 1 to 5, it can be seen that the ionic conductivity of the sulfide-based solid electrolyte tends to increase as the I content increases, but as shown in Example 6, it can be seen that it does not increase any further when the I content exceeds a certain level.

[0186] In addition, when Br and Cl are included in addition to I as halide elements, it can be seen that the ionic conductivity of the sulfide-based solid electrolyte is excellent, as shown in Examples 7 to 9.

[0187] On the other hand, when only two types of metals are included, it was found that the ionic conductivity of the sulfide-based solid electrolyte was significantly reduced, as shown in Comparative Examples 1 to 3.

[0188]

[0189] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. A sulfide-based solid electrolyte containing a metal element and a halide element, The above metal elements include germanium (Ge), silicon (Si) and antimony (Sb), A sulfide-based solid electrolyte, wherein the above halide element includes iodine (I).

2. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte represented by the following chemical formula 1: <Chemical Formula 1> Li 8-α-z Ge x Yes y Sb z S 6-α I α In the above chemical formula 1, 0.1 < x < 0.4, 0.2 < y < 0.5, 0.2 < z < 0.5, 0.8 < α < 1.

3.

3. In paragraph 1, A sulfide-based solid electrolyte, wherein the above halide-based element further includes at least one selected from the group consisting of bromine (Br) and chloride (Cl).

4. In paragraph 3, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte represented by the following chemical formula 2: <Chemical Formula 2> Li 8-α-z Ge x Si y Sb z S 6-α I α Br β Cl γ In the above chemical formula 2, 0.1 < x < 0.4, 0.2 < y < 0.5, 0.2 < z < 0.5, 0.8 < α + β + γ < 1.3, and the cases where α = 0 and β = γ = 0 are excluded.

5. In paragraph 1, The above sulfide-based solid electrolyte is a phosphorus-free sulfide-based solid electrolyte.

6. In paragraph 1, A sulfide-based solid electrolyte having an ionic conductivity of 4 to 8 mS / cm.

7. In paragraph 1, The above sulfide-based solid electrolyte is a sulfide-based solid electrolyte in the form of a sulfide-based solid electrolyte membrane.

8. An all-solid-state battery comprising a positive electrode, a negative electrode, and a sulfide-based solid electrolyte of claim 1 interposed therebetween.

9. In paragraph 8, An all-solid-state battery, wherein the above negative electrode is a lithium negative electrode containing lithium metal.

Images