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, the present invention relates to a sulfide-based solid electrolyte comprising lithium (Li), phosphorus (P), sulfur (S), and chlorine (Cl), wherein the phosphorus (P) site is substituted by a heterogeneous element, and when two or more selected from the group consisting of Ge, Sn, Sb, and Si are substituted at equivalent ratios, the ionic conductivity in the sulfide-based solid electrolyte can be improved.

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. 10-2024-0013764, dated January 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]

[0013] (Patent Document 1) Japanese Patent Publication No. 2015-22015

[0014] The inventors of the present invention have conducted various studies to solve the above problems and have confirmed that when two or more elements selected from the group consisting of Ge, Sn, Sb and Si are substituted for the P site in a sulfide-based solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S) and chlorine (C), the ionic conductivity of the sulfide-based solid electrolyte is improved.

[0015] Accordingly, the purpose of the present invention is to provide a sulfide-based solid electrolyte with improved ionic conductivity.

[0016] 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.

[0017] To achieve the above purpose, the present invention provides a sulfide-based solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S), chlorine (C), and M, wherein M is included in a form substituted for the phosphorus (P) site, and includes two or more selected from the group consisting of Ge, Sn, Sb, and Si.

[0018] In one embodiment of the present invention, a sulfide-based solid electrolyte is provided, which is represented by the following chemical formula 1:

[0019] <Chemical Formula 1>

[0020] Li (6-x) P y M (1-y) S (5-x) Cl (1+x)

[0021] The above x is 0 < x < 0.6, and the above y is 0 < y ≤ 0.9,

[0022] The above M is M1 a M2 b (0 < a+b ≤ 0.1, a+b = 1-y), M1 a M2 b M3 c (0 < a+b+c ≤ 0.1, a+b+c = 1-y) or M1 a M2 b M3 c M4 d (0 < a+b+c+d ≤ 0.1, a+b+c+d = 1-y),

[0023] The above M1, M2, M3 and M4 are different elements selected from the group consisting of Ge, Si, Sb and Sn, respectively.

[0024] In one embodiment of the present invention, two or more elements substituted for the phosphorus (P) position are substituted in an equal ratio, so that M is M1 a M2 b (0 < a+b ≤ 0.1, a+b = 1-y, a=b), M1 a M2 b M3 c (0 < a+b+c ≤ 0.1, a+b+c = 1-y, a=b=c) or M1 a M2 b M3 c M4 d A sulfide-based solid electrolyte is provided, wherein (0 < a+b+c+d ≤ 0.1, a+b+c+d = 1-y, a=b=c=d).

[0025] In one embodiment of the present invention, a sulfide-based solid electrolyte is provided, wherein the sulfide-based solid electrolyte has an argyrodite-type crystal structure.

[0026] In one embodiment of the present invention, a sulfide-based solid electrolyte is provided, wherein the ionic conductivity of the sulfide-based solid electrolyte is 4 to 6 mS / cm.

[0027] In one embodiment of the present invention, a sulfide-based solid electrolyte is provided, wherein the impurity content in the sulfide-based solid electrolyte is 0% to 5% based on the intensity of the XRD main peak.

[0028] In one embodiment of the present invention, a sulfide-based solid electrolyte is provided, wherein the impurity includes Li2S, LiCl or a compound thereof.

[0029]

[0030] The present invention also provides an all-solid-state battery comprising a positive electrode, a negative electrode, and the sulfide-based solid electrolyte interposed therebetween.

[0031] In one embodiment of the present invention, an all-solid-state battery is provided, wherein the negative electrode is a lithium negative electrode including lithium metal.

[0032] According to the solid electrolyte according to the present invention, by substituting two or more elements selected from the group consisting of Ge, Sn, Sb, and Si for some of the phosphorus (P) sites included in the sulfide-based solid electrolyte, the effect of increasing the solid solution of the substituting elements is improved, thereby improving the ionic conductivity of the sulfide-based solid electrolyte and reducing impurities.

[0033] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0034] 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.

[0035]

[0036] Sulfide-based solid electrolyte

[0037] The present invention relates to a sulfide-based solid electrolyte.

[0038] The sulfide-based solid electrolyte according to the present invention contains lithium (Li), phosphorus (P), sulfur (S), chlorine (C), and M, wherein M is included in a partially substituted form at the phosphorus (P) site, and includes two or more selected from the group consisting of Ge, Sn, Sb, and Si.

[0039] When two or more elements selected from the group consisting of Ge, Sn, Sb, and Si are substituted for the above P position, the disorder within the structure increases, allowing lithium ions to move smoothly, thereby improving the ionic conductivity of the sulfide-based solid electrolyte. Preferably, the two or more elements may be substituted in an equal ratio.

[0040] If one element is substituted in the P position, the one element may be precipitated as an impurity because the number that can be substituted in the structure of the sulfide-based solid electrolyte exceeds the number. At this time, if the substitution ratio of the one element is lowered and a different element is added together to increase the substitution ratio, the ionic conductivity of the sulfide-based solid electrolyte can be improved. For example, if only Sn is substituted as one element in the P position, P 0.94 Sn 0.06 In this case, two different elements, Sn and Si, are substituted in equal proportions to form P 0.94 Sn 0.03 Si0.03 In this case, the disorder within the structure increases, which can improve ionic conductivity.

[0041]

[0042] In one embodiment of the present invention, the sulfide-based solid electrolyte may be represented by the following chemical formula 1:

[0043] <Chemical Formula 1>

[0044] Li (6-x) P y M (1-y) S (5-x) Cl (1+x)

[0045] The above x is 0 < x < 0.6, and the above y is 0 < y ≤ 0.9,

[0046] The above M is M1 a M2 b (0 < a+b ≤ 0.1, a+b = 1-y), M1 a M2 b M3 c (0 < a+b+c ≤ 0.1, a+b+c = 1-y) or M1 a M2 b M3 c M4 d (0 < a+b+c+d ≤ 0.1, a+b+c+d = 1-y),

[0047] The above M1, M2, M3 and M4 are different elements selected from the group consisting of Ge, Si, Sb and Sn, respectively.

[0048] For example, the sulfide-based solid electrolyte represented by the chemical formula 1 is Li 5.5 P 0.94 Si 0.03 Sn 0.03 S 4.5 Cl 1.5 It could be.

[0049]

[0050] In addition, two or more elements substituted in the P position may be substituted in the same ratio. If the ratio of two or more elements substituted is not the same, impurities may be generated or ionic conductivity may decrease. For example, in the chemical formula 1, M is M1 a M2 b (0 < a+b ≤ 0.1, a+b = 1-y, a=b), M1 a M2 b M3 c (0 < a+b+c ≤ 0.1, a+b+c = 1-y, a=b=c) or M1 a M2 b M3 c M4 d (0 < a+b+c+d ≤ 0.1, a+b+c+d = 1-y, a=b=c=d) can be.

[0051]

[0052] In one embodiment of the present invention, the sulfide-based solid electrolyte may have an argyrodite-type crystal structure. The argyrodite-type crystal structure is a structure that can be obtained by replacing a portion of a material with chlorine.

[0053] The crystal structure of the above sulfide-based solid electrolyte is originally a face-centered cubic lattice (FCC) structure, so that lithium ions are trapped within sulfur atom octahedra during movement. However, when some of the substance is replaced with chlorine, 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. In the present invention, in addition to this argyrodite-type crystal structure, it has a structure in which two or more elements are substituted at the P site, so that the content of impurities is reduced and ionic conductivity can be further improved.

[0054]

[0055] In one embodiment of the present invention, the ionic conductivity of the sulfide-based solid electrolyte may be 4 to 6 mS / cm.

[0056] The above sulfide-based solid electrolyte may have two or more elements substituted at the P site, which may cause disorder in the crystal structure. This may facilitate the movement of lithium ions, increase the elemental solid solution ratio, improve ionic conductivity, and reduce impurities.

[0057]

[0058] In one embodiment of the present invention, the content of impurities in the sulfide-based solid electrolyte may be 0% to 5% based on the intensity of the XRD main peak, and the impurities may include Li2S, LiCl, or compounds thereof. The impurities may be impurities that are not dissolved in the structure of the raw material of the sulfide-based solid electrolyte and are precipitated, or may be impurities formed by these impurities forming a new type of impurity.

[0059]

[0060] Method for manufacturing sulfide-based solid electrolyte

[0061] The present invention also relates to a method for producing a sulfide-based solid electrolyte.

[0062] The method for manufacturing a sulfide-based solid electrolyte according to the present invention comprises the steps of (S1) pulverizing a raw material; and (S2) heat-treating the powder obtained in step (S1). This may also be referred to as a solid-state synthesis method.

[0063]

[0064] Hereinafter, the method for manufacturing a sulfide-based solid electrolyte according to the present invention will be described in more detail step by step.

[0065]

[0066] In one embodiment of the present invention, in the step (S1), the raw material can be pulverized.

[0067] The above raw material may refer to a raw material for each element included in a sulfide-based solid electrolyte. The raw material is not particularly limited as long as it is a raw material commonly used in the art as a raw material for each element. For example, the raw material may include a raw material for forming a sulfide-based solid electrolyte and a raw material for a substitutional element. The raw material for forming the sulfide-based solid electrolyte includes lithium sulfide (Li2S), diphosphorus pentasulfide (P2S5), and lithium chloride (LiCl), and the raw material for the substitutional element may include two or more selected from the group consisting of silicon (Si), silicon sulfide (SiS2), tin sulfide (SnS2), germanium sulfide (GeS2), and antimony sulfide (Sb2S5). In addition, for 1 mol of the lithium sulfide (Li2S), 0.1 to 0.5 mol of phosphorus pentasulfide (P2S5), 0.5 to 1.5 mol of lithium chloride (LiCl), and 0.01 to 0.1 mol of the raw material of the substitution element can be used. Specifically, the phosphorus pentasulfide (P2S5) can be 0.1 mol or more, 0.15 mol or more, or 0.2 mol or more, and 0.5 mol or less, 0.4 mol or less, or 0.3 mol or less can be used. In addition, lithium chloride (LiCl) can be 0.5 mol or more, 0.6 mol or more, or 0.7 mol or more, and 1.5 mol or less, 1.4 mol or less, 1.3 mol or less, 1.2 mol or less, 1.1 mol or less, 1.0 mol or less, 0.9 mol or less, or 0.8 mol or less can be used. Additionally, the raw material of the substitution element may be 0.01 mol or more, 0.02 mol or more, or 0.03 mol or more, and may be used in an amount of 0.1 mol or less, 0.09 mol or less, or 0.08 mol or less, 0.07 mol or less, 0.06 mol or less, or 0.05 mol or less.

[0068] In addition, the grinding is not particularly limited as long as it can be performed in a way that can obtain powder. For example, the grinding method may be milling, hand milling, ball milling, etc.

[0069]

[0070] In one embodiment of the present invention, in step (S2), the powder obtained in step (S1) may be heat-treated.

[0071] The above heat treatment can be performed under conditions of a temperature of 400°C to 600°C and a time of 10 to 14 hours in an inert atmosphere. The inert atmosphere may refer to a nitrogen, helium, argon, or carbon dioxide atmosphere. The temperature may be 400°C or higher, 450°C or higher, or 500°C or higher, and may be 600°C or lower, 580°C or lower, or 560°C or lower.

[0072] 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.

[0073]

[0074] All-solid-state batteries

[0075] The present invention also relates to an all-solid-state battery comprising the above sulfide-based solid electrolyte.

[0076] An all-solid-state battery according to the present invention includes: the sulfide-based solid electrolyte; a positive electrode formed on one surface of the sulfide-based solid electrolyte; and a negative electrode formed on the other surface of the sulfide-based solid electrolyte.

[0077]

[0078] In one embodiment of the present invention, the positive electrode may include a positive electrode active material, a conductive material, and a binder.

[0079]

[0080] 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.

[0081] The above positive electrode active material layer includes a positive electrode active material, a conductive material, and a binder.

[0082] 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-yNi-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.

[0083] 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.

[0084]

[0085] 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).

[0086] 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.

[0087]

[0088] 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).

[0089] 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.

[0090]

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095]

[0096] 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.

[0097] 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.

[0098] 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).

[0099] 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.

[0100] 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.

[0101] In addition, the binder is as described above in the positive electrode active material layer.

[0102] In addition, the above-described conductive material is as described above in the positive electrode active material layer.

[0103] 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.

[0104] 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.

[0105]

[0106] battery module

[0107] 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.

[0108] 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.

[0109] 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.

[0110]

[0111] Example 1

[0112] In a glove box, raw materials were pulverized by hand milling for 30 minutes, and then heat-treated at 520°C for 12 hours under an Ar atmosphere to manufacture a sulfide-based solid electrolyte using a solid-state synthesis method. At this time, the raw materials used were 2 mol of lithium sulfide (Li2S, Mitsuwa Chemical product), 0.47 mol of diphosphorus pentasulfide (P2S5, Aldrich product), 1.5 mol of lithium chloride (LiCl, Aldrich product), 0.03 mol of silicon (Si, Sigma-Aldrich product), and 0.03 mol of tin sulfide (SnS2, Kojundo product).

[0113]

[0114] Comparative Example 1

[0115] Li was prepared in the same manner as in Example 1, except that the substituent element was not substituted at the P position. 5.5 PS 4.5 Cl 1.5 was manufactured. At this time, the raw materials used were 2 mol of lithium sulfide (Li2S, Mitsuwa Chemical product), 0.5 mol of diphosphorus pentasulfide (P2S5, Aldrich product), and 1.5 mol of lithium chloride (LiCl, Aldrich product).

[0116]

[0117] Comparative Example 2

[0118] Li was prepared in the same manner as in Example 1, except that only one substituent element, i.e., Sn, was substituted in the P position. 5.5 P 0.94 Sn 0.06 S 4.5 Cl 1.5 was manufactured. At this time, the raw materials used were 2 mol of lithium sulfide (Li2S, Mitsuwa Chemical product), 0.47 mol of diphosphorus pentasulfide (P2S5, Aldrich product), 1.5 mol of lithium chloride (LiCl, Aldrich product), and 0.06 mol of tin sulfide (SnS2, Kojundo product).

[0119]

[0120] Experimental Example 1: Ionic Conductivity Measurement

[0121] 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.

[0122] 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.

[0123] 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.

[0124]

[0125] <Formula 1>

[0126]

[0127]

[0128] 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.

[0129]

[0130] Table 1 below shows the composition and measured ionic conductivity of the sulfide-based solid electrolytes manufactured in Examples and Comparative Examples. The composition of the sulfide-based solid electrolytes described in Table 1 below shows the composition of each element in Chemical Formula 1.

[0131]

[0132] LiPSnSbSiSClIonic Conductivity (mS / cm)Example 15.50.940.030.000.034.51.55.4Comparative Example 15.510004.51.53.89Comparative Example 25.50.940.06004.51.54.26

[0133]

[0134] Referring to Table 1 below, it can be seen that the ionic conductivity of Example 1, in which part of the P site is substituted with two types of substituent elements, is the best.

[0135]

[0136] 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. Contains lithium (Li), phosphorus (P), sulfur (S), chlorine (C) and M. A sulfide-based solid electrolyte, wherein the above M is included in a substituted form in the above P site, and includes two or more selected from the group consisting of Ge, Sn, Sb, and Si.

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 (6-x) P y M (1-y) S (5-x) Cl (1+x) The above x is 0 < x < 0.6, and the above y is 0 < y ≤ 0.9, The above M is M1 a M2 b (0 < a+b ≤ 0.1, a+b = 1-y), M1 a M2 b M3 c (0 < a+b+c ≤ 0.1, a+b+c = 1-y) or M1 a M2 b M3 c M4 d (0 < a+b+c+d ≤ 0.1, a+b+c+d = 1-y), The above M1, M2, M3 and M4 are different elements selected from the group consisting of Ge, Si, Sb and Sn, respectively.

3. In paragraph 1, Two or more elements substituted in the above P site are substituted in the same weight ratio, so that M is M1 a M2 b (0 < a+b ≤ 0.1, a+b = 1-y, a=b), M1 a M2 b M3 c (0 < a+b+c ≤ 0.1, a+b+c = 1-y, a=b=c) or M1 a M2 b M3 c M4 d A sulfide-based solid electrolyte, wherein (0 < a+b+c+d ≤ 0.1, a+b+c+d = 1-y, a=b=c=d).

4. In paragraph 1, The above sulfide-based solid electrolyte has an argyrodite-type crystal structure.

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

6. In paragraph 1, A sulfide-based solid electrolyte, wherein the impurity content in the sulfide-based solid electrolyte is 0% to 5% based on the intensity of the XRD main peak.

7. In paragraph 6, A sulfide-based solid electrolyte, wherein the impurity comprises Li2S, LiCl or a compound thereof.

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.

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