Method for producing solid sulfide electrolyte

Abstract

The present invention relates to a method for producing a solid sulfide electrolyte and a solid sulfide electrolyte obtainable by the method. The present inventors have surprisingly found that when a solid electrolyte precursor mixture is mixed with an organic liquid other than ethanol or methanol and then heat-treated to obtain a solid sulfur electrolyte, the conductivity of the obtained solid sulfur electrolyte is increased.

Description

Technical Field

[0001] The present invention relates to a method for producing a solid sulfide electrolyte and a solid sulfide electrolyte obtainable from the method.

Background Art

[0002] With the rapid development of small and lightweight electronic products, electronic devices, communication devices, etc., and the increasing need for electric vehicles due to environmental problems, there is a demand for improving the performance of secondary batteries used as power sources for these products. Among them, lithium secondary batteries have attracted attention as high-performance batteries due to their high energy density and high reference electrode potential.

[0003] However, the electrolytes conventionally used in lithium secondary batteries are liquid electrolytes, for example, organic solvents. Therefore, safety problems such as electrolyte leakage and the risk of fire can continuously occur.

[0004] Recently, in order to improve the safety characteristics of lithium secondary batteries, solid batteries containing solid electrolytes instead of liquid electrolytes have been used and have received much attention. For example, solid electrolytes are generally safer than liquid electrolytes due to their nonflammability or flame retardancy.

[0005] Examples of solid electrolytes include oxide-based solid electrolytes, polymer-based electrolytes, and sulfide-based electrolytes. Sulfide-based electrolytes, for example, sulfide-based solid electrolytes having an argyrodite-type crystal structure, are generally used because they have a higher range of lithium ion conductivity compared to oxide-based and polymer-based solid electrolytes.

[0006] Conventionally, in the method for producing a solid sulfide electrolyte, ethanol is used as a solvent or a liquid. Typically, precursors of LiCl, P2S5, and Li2S are dissolved in ethanol, the mixture is stirred, the solvent is removed, and the resulting mixture is fired to obtain a solid sulfide electrolyte such as Li6PS5Cl and Li6PS5Br. Examples of this liquid-based approach using ethanol are described in US Patent Application Publication No. 2020 / 0119394 (A1) and US Patent Application Publication No. 2019 / 0173127 (A1). US Patent Application Publication No. 2019 / 0074544 (A1) describes a similar synthetic route using Li3PS4, LiCl, and Li2S as precursors dissolved in ethanol. Ethanol has been considered a suitable solvent for the synthesis of Li6PS5Cl because the precursors are completely dissolved in ethanol, promoting the reaction towards the formation of the solid sulfide electrolyte. However, the inventors have observed that alcohols as solvents, such as ethanol or methanol, are detrimental to the conductivity obtained of the solid sulfide electrolyte.

[0007] Therefore, it is necessary to provide a method for producing a solid sulfide electrolyte that uses a liquid different from ethanol and does not produce a solid sulfide electrolyte with low conductivity.

[0008] An object of the present invention is to provide a method for producing a solid sulfide electrolyte.

[0009] A further object of the present invention is to provide a solid sulfide electrolyte obtainable from the method.

[0010] A further object of the present invention is to provide a solid sulfide electrolyte having a thiogermanate-type crystal structure.

[0011] A further object of the present invention is to provide a battery including the solid sulfide electrolyte.

Summary of the Invention

[0012] In a first aspect, the object of the present invention is achieved by providing a solid electrolyte precursor mixture and a liquid without hydroxyl moieties, thereby providing a method for producing a solid sulfide electrolyte.

[0013] The inventors have surprisingly found that by mixing a solid electrolyte precursor mixture with an organic liquid other than ethanol or methanol and subsequently heat-treating to obtain a solid sulfur electrolyte, the conductivity of the resulting solid sulfur electrolyte is higher compared to that of a solid sulfur silver germanium ore obtained after mixing the solid electrolyte precursor mixture with ethanol or methanol.

[0014] While not wishing to be bound by any theory, the inventors believe that the alcohol solvent nucleophilically attacks the PS4 3- units of the solid sulfur electrolyte, thereby decomposing the sulfur-based solid electrolyte to form PO4 3- , PSO3 3- and / or PS2O2 3- decomposition products, for example, Li3PO4. These decomposition products are detrimental to the conductivity of the resulting solid sulfide electrolyte. A possible solution is to recrystallize the solid sulfide electrolyte in ethanol to obtain a pure compound exhibiting high conductivity (ACS Appl. Energy Mater. 2018, 1, 8, 3622 - 3629). However, the decomposition of the solid sulfur electrolyte or the solid sulfur electrolyte precursor results in an overall loss of the yield of the solid sulfide electrolyte.

[0015] In a further aspect, the present invention provides a solid sulfide electrolyte obtainable by the method according to the present invention.

[0016] In a further aspect, the present invention provides a solid sulfide electrolyte having a thioargentite-type crystal structure.

[0017] In a further aspect, the present invention provides a battery comprising a solid sulfide electrolyte according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0019] To enable the implementation of the present invention, in the drawings and the following mode for carrying out the invention, preferred embodiments are described in detail. The present invention is described with reference to these specific preferred embodiments, but it should be understood that the present invention is not limited to these preferred embodiments. On the contrary, the present invention includes numerous alternatives, modifications, and equivalents as will become apparent in view of the following detailed description and the accompanying drawings.

[0020] As used in this specification and the claims, the term "comprising" should not be construed as being limited to the means recited thereafter, and does not exclude other elements or steps. It should be construed as specifying the presence of the described features, integers, steps, or components as recited, but does not exclude the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" should not be limited to a composition consisting only of components A and B. It means, with respect to the present invention, that the only relevant components of the composition are A and B. Thus, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of".

[0021] As used herein, the term "solid-state battery" refers to a cell or battery that includes only solid or substantially solid components such as solid electrodes (e.g., an anode and a cathode) and a solid electrolyte.

[0022] As used herein, the term "argyrodite-type crystal structure" refers to a crystal structure having a crystal structure or system similar to that of naturally occurring Ag8GeS6 and Li7S6 (argyrodite). The argyrodite-type crystal can be orthorhombic, having a Pna21 space group and a unit cell with a = 15.149, b = 7476, c = 10589 [Å], and Z = 4. In some embodiments, the argyrodite-type crystal structure can also be determined experimentally, for example, by X-ray diffraction by observing peaks near 2θ = 15.5 ± 1°, 18 ± 1°, 26 ± 1°, 30.5 ± 1°, and 32 ± 1° using CuKα-radiation.

[0023] As used herein, the ionic conductivity refers to the ionic conductivity measured at 25 °C by electrochemical impedance spectroscopy (EIS). The ionic conductivity is preferably measured with a stainless steel plunger on a compressed sample having a diameter of 10 mm and a total mass of 120 mg to which a pressure of 5 T is applied (applying a pressure of 80 kg / cm 2 ). A suitable conductivity analyzer is a potentiostat equipped with a frequency analyzer such as those available from Biologic.

[0024] As used herein, the electronic conductivity refers to the electronic conductivity measured at 25 °C. The electronic conductivity is preferably measured with a stainless steel plunger on a compressed sample having a diameter of 10 mm and a total mass of 120 mg to which a pressure of 5 T is applied (applying a pressure of 80 kg / cm 2 ). Preferably, the ionic conductivity is measured by stepwise potentiostatic polarization at 0.2, 0.4, 0.6 V and 0.8 V.

[0025] As used herein, X-ray diffraction (XRD) refers to an XRD experiment performed using a Bruker D8 Advanced diffractometer with Cu radiation (λ1 = 1.54056 Å, λ2 = 1.54439 Å).

[0026] Manufacturing method As described above, in a first aspect, the present invention provides the following continuous steps, namely, (i) providing an electrolyte precursor mixture comprising a solid electrolyte precursor mixture containing Li2S, Li3PS4 and LiX (wherein X is a halogen selected from F, Cl, Br, I or combinations thereof) and a liquid containing no hydroxyl moiety; (ii) mixing the electrolyte precursor mixture obtained in step (i); and (iii) heat-treating the mixed electrolyte precursor mixture obtained in step (ii) to obtain a solid sulfide electrolyte having a thiogermanate-type crystal structure, a method for producing a solid sulfide electrolyte.

[0027] As used herein, the term "solid electrolyte precursor mixture" refers to an electrolyte precursor mixture that is essentially free of any liquid. The term "essentially free of liquid" means that the solid electrolyte precursor mixture contains less than 10% by weight, preferably less than 7.5% by weight, more preferably less than 5% by weight, even more preferably less than 2.5% by weight, and most preferably less than 1% by weight of liquid, based on the total weight of the solid electrolyte precursor mixture. In a more preferred embodiment, the solid electrolyte precursor mixture contains less than 1000 ppm, preferably less than 500 ppm, more preferably less than 100 ppm, even more preferably less than 50 ppm, and most preferably less than 10 ppm of liquid, based on the total weight of the solid electrolyte precursor mixture.

[0028] In the context of the present invention, a liquid is considered to be an organic or aqueous compound that is liquid under standard conditions of temperature and pressure as defined by the IUPAC. Thus, the boiling and melting points are considered to be the boiling and melting points at standard atmospheric pressure, i.e., 101325 Pa. As will be understood by those skilled in the art, the presence of an organic liquid can be measured by thermogravimetric analysis (TGA) or nuclear magnetic resonance (NMR) spectroscopy, and the presence of an aqueous liquid, such as water, can be measured by Karl Fischer titration.

[0029] The term "solid sulfide electrolyte" as used herein refers to a solid sulfide electrolyte that is essentially free of any liquid. The term "essentially free of liquid" means that the solid sulfide electrolyte contains less than 10 wt.% liquid based on the total weight of the solid sulfide electrolyte, preferably less than 7.5 wt.%, more preferably less than 5 wt.%, even more preferably less than 2.5 wt.%, and most preferably less than 1 wt.% liquid based on the total weight of the solid sulfide electrolyte. In a more preferred embodiment, the solid sulfide electrolyte contains less than 1000 ppm liquid based on the total weight of the solid sulfide electrolyte, preferably less than 500 ppm liquid based on the total weight of the solid sulfide electrolyte, more preferably less than 100 ppm liquid based on the total weight of the solid sulfide electrolyte, even more preferably less than 50 ppm liquid based on the total weight of the solid sulfide electrolyte, and most preferably less than 10 ppm liquid.

[0030] As will be appreciated by one of skill in the art, any crystal structure of Li3PS4 can be used in the methods of the present invention, particularly the γ-, α- and β-polymorphs of Li3PS4.

[0031] In a preferred embodiment of the present invention, the solid sulfide electrolyte is represented by the formula (I): Li 7-y P.S. 6-y X y (I) is represented by In the method according to the present invention, y=0.8-1.7. As will be understood by those skilled in the art, when y is 0.8-1.7, it is possible to obtain a solid sulfide electrolyte having a arginine-type crystal structure. In a more preferred embodiment, y is 0.8-1.7, preferably y is 0.9 to 1.6, more preferably y is 1.0 to 1.4.

[0032] In a highly preferred embodiment, the solid sulfide electrolyte is of formula (II) Li6PS5X (II) The method according to the present invention is represented by:

[0033] A preferred embodiment is a method according to the present invention, wherein X = F, Cl, Br, I, or a combination thereof, preferably X = Cl, Br, or a combination thereof, more preferably X = Cl.

[0034] According to a preferred embodiment of the present invention, there is provided a solid sulfide electrolyte in which at least 50 mol% of X represents Cl, preferably at least 80 mol% of X represents Cl, and most preferably X represents Cl.

[0035] According to a preferred embodiment of the present invention, there is provided a solid sulfide electrolyte in which X represents F, Cl, Br, I, or a combination thereof, and at least 50 mol% of X represents Cl, preferably at least 80 mol% of X represents Cl.

[0036] According to a preferred embodiment of the present invention, there is provided a solid sulfide electrolyte in which at least 50 mol% of X represents F, preferably at least 80 mol% of X represents F, and most preferably X represents F.

[0037] According to a preferred embodiment of the present invention, there is provided a solid sulfide electrolyte in which X represents F, Cl, Br, I, or a combination thereof, and at least 50 mol% of X represents Br, preferably at least 80 mol% of X represents Br.

[0038] According to a preferred embodiment of the present invention, there is provided a solid sulfide electrolyte in which at least 50 mol% of X represents Br, preferably at least 80 mol% of X represents Br, and most preferably X represents Br.

[0039] According to a preferred embodiment of the present invention, there is provided a solid sulfide electrolyte in which X represents F, Cl, Br, I, or a combination thereof, and at least 50 mol% of X represents Br, preferably at least 80 mol% of X represents Br.

[0040] According to a preferred embodiment of the present invention, there is provided a solid sulfide electrolyte in which at least 50 mol% of X represents I, preferably at least 80 mol% of X represents I, and most preferably X represents I.

[0041] According to a preferred embodiment of the present invention, there is provided a solid sulfide electrolyte in which X represents F, Cl, Br, I or a combination thereof, and at least 50 mol% of X represents I, preferably at least 80 mol% of X represents I.

[0042] A highly preferred embodiment is a method according to the present invention wherein X is F, Cl, Br or I, preferably X = Cl or Br, more preferably X = Cl.

[0043] A preferred embodiment is a method according to the present invention wherein the molar ratio of Li2S:Li3PS4:LiX is (0.5 to 1.5):(0.5 to 1.5):(0.5 to 1.5), preferably (0.75 to 1.25):(0.75 to 1.25):(0.75 to 1.25), more preferably (0.9 to 1.1):(0.9 to 1.1):(0.9 to 1.1). In a more preferred embodiment, the molar ratio of Li2S:Li3PS4:LiX is (0.95 to 1.05):(0.95 to 1.05):(0.95 to 1.05), preferably (0.98 to 1.02):(0.98 to 1.02):(0.98 to 1.02), more preferably (0.99 to 1.01):(0.99 to 1.01):(0.99 to 1.01). In a highly preferred embodiment, the molar ratio of Li2S:Li3PS4:LiX is about 1:1:1.

[0044] A preferred embodiment is a method according to the present invention, wherein the molar ratio of Li:P:S:X is (5 to 7):(0.5 to 1.5):(4 to 6):(0.5 to 1.5), preferably (5.5 to 6.5):(0.75 to 1.25):(4.5 to 5.5):(0.75 to 1.25), more preferably (5.75 to 6.25):(0.9 to 1.1):(4.75 to 5.25):(0.9 to 1.1). In a more preferred embodiment of the present invention, the molar ratio of Li:P:S:X is (5.9 to 6.1):(0.95 to 1.05):(4.9 to 5.1):(0.95 to 1.05), preferably (5.95 to 6.05):(0.98 to 1.02):(4.95 to 5.05):(0.98 to 1.02), more preferably (5.98 to 6.02):(0.99 to 1.01):(4.98 to 5.02):(0.99 to 1.01). In a highly preferred embodiment, the molar ratio of Li:P:S:X is about 6:1:5:1.

[0045] As will be understood by those skilled in the art, a liquid that does not contain a hydroxyl moiety is any liquid that does not contain a hydroxyl functional group (also known as a hydroxy functional group or -OH group) as a functional part of the liquid. Examples of liquids that do not conform to this definition are alcohols such as ethanol and methanol, water or glycols.

[0046] A preferred embodiment is a method according to the present invention, wherein the liquid that does not contain a hydroxyl moiety is an organic liquid. In certain preferred embodiments, the liquid that does not contain a hydroxyl moiety is an aprotic liquid. As will be understood by those skilled in the art, an aprotic liquid is a liquid in which a hydrogen atom is not directly bonded to an electronegative atom such as O and N. In other words, an aprotic liquid does not contain an O-H or N-H functional moiety. In certain preferred embodiments, the aprotic liquid is a liquid lacking acidic protons.

[0047] A more preferred embodiment is a method according to the invention, wherein the liquid that does not contain a hydroxyl moiety is selected from the group consisting of hydrocarbons, esters, ketones, aldehydes, ethers, nitriles, amines, amides, carbonates, sulfones, sulfoxides, sulfonates, thiols, fluorinated compounds, and combinations thereof, preferably selected from the group consisting of amides, esters, ethers, nitriles, aromatic hydrocarbons, and combinations thereof, and most preferably selected from the group consisting of amides, ethers, nitriles, aromatic hydrocarbons, and combinations thereof. In certain preferred embodiments, the liquid that does not contain a hydroxyl moiety is selected from the group consisting of aromatic hydrocarbons, esters, ethers, nitriles, amides, sulfoxides, thiols, and combinations thereof, preferably the liquid that does not contain a hydroxyl moiety is selected from the group consisting of aromatic hydrocarbons, esters, ethers, nitriles, amides, sulfoxides, and thiols. Examples of hydrocarbons are straight-chain or branched-chain hydrocarbons, such as straight-chain or branched-chain pentane, straight-chain or branched-chain hexane, straight-chain or branched-chain octane, straight-chain or branched-chain nonane, straight-chain or branched-chain decane, straight-chain or branched-chain undecane, and straight-chain or branched-chain dodecane. Further examples of hydrocarbons are cyclic alkanes such as cyclopentane, cyclohexane, cycloheptane, or cyclooctane. Further examples of hydrocarbons are aromatic hydrocarbons such as benzene, toluene, o-, m-, or p-xylene. Further examples of hydrocarbons in the present invention are halogenated alkyls such as chloroform, methyl chloride, or dichloromethane. Examples of esters are methyl acetate or ethyl acetate (EtOAc). Examples of ketones are acetone or butanone. Examples of ethers are dimethyl ether, diethyl ether, methyl ethyl ether, tetrahydrofuran, or dimethoxyethane (DME). An example of a carbonate is dimethyl carbonate. Examples of amines are pyridine, aniline, hydrazine, triethylamine, diethylamine, monoethylamine, ethylenediamine, or ammonia. Examples of amides are dimethylformamide (DMF) or N-methyl-2-pyrrolidone. An example of a sulfoxide is dimethyl sulfoxide (DMSO). An example of a sulfone is sulfolane.Examples of thiols are butanethiol. Examples of nitriles are acetonitrile. Examples of fluorine-containing compounds are benzene fluoride, heptane fluoride, 2,3-dihydroperfluoropentane, and 1,1,2,2,3,3,4-heptafluorocyclopentane.

[0048] In a highly preferred embodiment, the liquid without a hydroxyl moiety is selected from the group consisting of DMF, EtOAc, DME, CH3CN, xylene, DMSO, butanethiol, ethylenediamine, and combinations thereof, preferably selected from the group consisting of DMF, EtOAc, DME, CH3CN, xylene, and combinations thereof, and most preferably selected from the group consisting of DMF, DME, CH3CN, xylene, and DMSO.

[0049] As demonstrated in the attached examples, the solid sulfur electrolyte is not formed prior to the heat treatment of the mixed electrolyte precursor mixture. Thus, the liquid without a hydroxyl moiety serves as a mixing medium for the electrolyte precursor mixture. The inventors have surprisingly found that one or more precursors and / or the solid sulfide electrolyte need not be completely soluble in the liquid without a hydroxyl moiety. In contrast, when ethanol is used as the liquid, all precursors and the solid sulfide electrolyte are completely dissolved, and the formation of the solid sulfide electrolyte is already observed prior to firing. However, as demonstrated in the attached examples, using ethanol as the liquid in the method for producing the solid sulfide electrolyte is detrimental to the ionic conductivity and / or electronic conductivity of the solid sulfide electrolyte.

[0050] In a preferred embodiment, the amount of the solid electrolyte precursor mixture is more than 0.5% by weight, preferably more than 1% by weight, more preferably more than 2.5% by weight based on the total weight of the solid electrolyte precursor mixture and the liquid without a hydroxyl moiety. In a preferred embodiment, the amount of the solid electrolyte precursor mixture is less than 15% by weight, preferably less than 10% by weight, more preferably less than 7.5% by weight based on the total weight of the solid electrolyte precursor mixture and the liquid without a hydroxyl moiety. In a preferred embodiment, the amount of the solid electrolyte precursor mixture is 0.5 to 15% by weight, preferably 1 to 10% by weight, more preferably 2.5 to 7.5% by weight based on the total weight of the solid electrolyte precursor mixture and the liquid without a hydroxyl moiety.

[0051] In a preferred embodiment, the electrolyte precursor mixture contains at least 90% by weight of a liquid without a hydroxyl moiety, more preferably at least 92% by weight of a liquid without a hydroxyl moiety, most preferably at least 94% by weight of a liquid without a hydroxyl moiety based on the total weight of the electrolyte precursor mixture.

[0052] In a preferred embodiment, the electrolyte precursor mixture contains 90 to 99% by weight of a liquid without a hydroxyl moiety, more preferably 92 to 98% by weight of a liquid without a hydroxyl moiety, most preferably 94 to 97% by weight of a liquid without a hydroxyl moiety based on the total weight of the electrolyte precursor mixture.

[0053] In a preferred embodiment, the electrolyte precursor mixture contains 0.5 to 15% by weight of the solid electrolyte precursor mixture, preferably 1 to 10% by weight of the solid electrolyte precursor mixture, more preferably 2.5 to 7.5% by weight of the solid electrolyte precursor mixture based on the total weight of the electrolyte precursor mixture.

[0054] In certain particularly preferred embodiments, the electrolyte precursor mixture consists of a solid electrolyte precursor mixture and a liquid that does not contain hydroxyl moieties.

[0055] Preferred embodiments are those in which step (ii) further comprises the following steps, namely, (ii)a mixing the electrolyte precursor mixture obtained in step (i), and (ii)b drying the mixed electrolyte precursor obtained in (ii)a thereby obtaining a solid electrolyte mixture, which is a method according to the invention.

[0056] As used herein, the term "solid electrolyte mixture" refers to an electrolyte mixture that essentially contains no liquid. The term "essentially liquid-free" means that the solid electrolyte mixture contains less than 10% by weight, preferably less than 7.5% by weight, more preferably less than 5% by weight, even more preferably less than 2.5% by weight, and most preferably less than 1% by weight of liquid based on the total weight of the solid electrolyte mixture. In a more preferred embodiment, the solid electrolyte mixture contains less than 1000 ppm, preferably less than 500 ppm, more preferably less than 100 ppm, even more preferably less than 50 ppm, and most preferably less than 10 ppm of liquid based on the total weight of the solid electrolyte mixture.

[0057] Preferred embodiments are methods according to the invention in which the electrolyte precursor mixture is mixed at a mixing rate of 100 - 1500 rpm, preferably 200 - 1000 rpm, and most preferably 400 - 800 rpm.

[0058] A preferred embodiment is a method according to the present invention, wherein the mixing of the electrolyte precursor mixture in step (ii) and / or step (ii)a is carried out for a mixing time of at least 1 minute, preferably at least 0.5 hour, more preferably at least 1 hour, even more preferably at least 2 hours, even more preferably at least 5 hours, and most preferably at least 10 hours. A preferred embodiment is a method according to the present invention, wherein the mixing is carried out for a mixing time of less than 72 hours, preferably less than 60 hours, more preferably less than 50 hours, even more preferably less than 40 hours, even more preferably less than 36 hours, and most preferably less than 30 hours. A preferred embodiment is a method according to the present invention, wherein the solid electrolyte precursor mixture is mixed for a mixing time of from 1 hour to 72 hours, preferably from 2 hours to 60 hours, more preferably from 10 hours to 30 hours.

[0059] According to a highly preferred embodiment of the present invention, the mixing of the solid electrolyte precursor mixture in step (ii) and / or step (ii)a is at a mixing speed of -100 to 1500 rpm, preferably 200 to 1000 rpm, and most preferably 400 to 800 rpm, and for a mixing time of -1 hour to 72 hours, preferably 2 hours to 60 hours, and more preferably 10 hours to 30 hours, and is carried out.

[0060] A preferred embodiment is a method according to the present invention, wherein the mixing of the electrolyte precursor mixture is carried out at a temperature of at least 5°C, preferably at least 10°C, and more preferably at least 15°C. A preferred embodiment is a method according to the present invention, wherein the mixing is carried out at a temperature of less than 50°C, preferably less than 40°C, and more preferably less than 30°C. A preferred embodiment is a method according to the present invention, wherein the mixing is carried out at a temperature of 5 to 50°C, preferably 10 to 40°C, and more preferably 15 to 30°C.

[0061] A preferred embodiment is the drying of the mixed electrolyte precursor in step (ii)b, in which a liquid containing no hydroxyl moiety is removed by heating the mixed electrolyte precursor obtained in step (ii)a. Preferably, the liquid containing no hydroxyl moiety is removed by heating under reduced pressure. As will be understood by those skilled in the art, if the liquid containing no hydroxyl moiety has a high (higher) boiling point, the temperature of heating the mixed electrolyte precursor obtained in step (ii)a should be increased and / or the pressure should be reduced as much as possible, whereby the liquid containing no hydroxyl moiety is more easily removed. Examples of drying the mixed electrolyte precursor include, but are not limited to, rotary evaporation, vacuum distillation and / or drying in an oven or a vacuum oven.

[0062] A preferred embodiment is a method according to the invention, in which the heat treatment in step (iii) is carried out at a temperature of at least 100 °C, preferably at least 200 °C, more preferably at least 300 °C, more preferably at least 400 °C, even more preferably at least 450 °C, most preferably at least 500 °C. A preferred embodiment is a method according to the invention, in which the heat treatment in step (iii) is carried out at a temperature of less than 1000 °C, preferably less than 900 °C, more preferably less than 800 °C, even more preferably less than 700 °C, even more preferably less than 600 °C, most preferably less than 550 °C. A preferred embodiment is a method according to the invention, in which the heat treatment in step (iii) is carried out at a temperature of 100 - 1000 °C, preferably 300 - 700 °C, more preferably 350 - 650 °C.

[0063] As will be understood by those skilled in the art, the heat treatment of the mixed electrolyte mixture in step (iii) for obtaining a solid sulfide electrolyte having an argyrodite-type crystal structure is also known as the firing of the solid electrolyte mixture towards the formation of a solid sulfide electrolyte having an argyrodite-type crystal structure.

[0064] A preferred embodiment is a method according to the present invention, wherein the heat treatment in step (iii) is carried out in an inert atmosphere, preferably in an argon atmosphere, or in an atmosphere containing hydrogen sulfide gas, preferably in an atmosphere consisting of hydrogen sulfide gas.

[0065] A preferred embodiment is a method according to the present invention, wherein the heat treatment of the solid electrolyte mixture in step (iii) is at least 1 minute, preferably at least 0.5 hours, more preferably at least 1 hour, even more preferably at least 1.5 hours, and most preferably at least 2 hours. A preferred embodiment is a method according to the present invention, wherein the heat treatment of the solid electrolyte mixture in step (iii) is less than 48 hours, preferably less than 24 hours, more preferably less than 18 hours, even more preferably less than 12 hours, and most preferably less than 10 hours. A preferred embodiment is a method according to the present invention, wherein the heat treatment of the solid electrolyte mixture in step (iii) is from 0.5 hours to 24 hours, preferably from 1 hour to 12 hours, more preferably from 1.5 hours to 10 hours.

[0066] Solid sulfide electrolyte A second aspect of the present invention is to provide a solid sulfide electrolyte obtainable by the method according to the present invention. As will be understood by those skilled in the art, all embodiments relating to the method for producing a solid sulfide electrolyte according to the present invention are equally applicable to the solid sulfide electrolyte obtainable by the method according to the present invention.

[0067] The preferred embodiment is a solid sulfide electrolyte according to the present invention that substantially does not contain a phase formed from Li2S, LiCl, Li4P2S6 and / or Li3PS4, and the peak intensity of Li2S, LiCl, Li4P2S6 and / or Li3PS4 is less than 30%, preferably less than 25%, more preferably less than 20%, even more preferably less than 10%, and most preferably less than 5% of the peak intensity of Li6PS5Cl, as measured by XRD. According to a preferred embodiment, the solid sulfide electrolyte according to the present invention has a purity of at least 70%, preferably at least 75%, more preferably at least 80%, even more preferably 90%, and most preferably at least 95%, as measured by XRD.

[0068] The preferred embodiment is a solid sulfide electrolyte according to the present invention that has an XRD pattern around 2θ = 15.5 ± 1°, 18 ± 1°, 26 ± 1°, 30.5 ± 1° and 32 ± 1° using CuKα - rays.

[0069] The preferred embodiment is by NMR, preferably 31 as measured by 31P NMR, substantially does not contain a phase formed from PO4 such as Li3PO4 3- and the peak area of PO4 3- is less than 30%, preferably less than 25%, more preferably less than 20%, even more preferably less than 10%, and most preferably less than 5% of the total area, and is a solid sulfide electrolyte according to the present invention. The preferred embodiment is by NMR, preferably 31 as measured by 31P NMR, substantially does not contain a phase formed from PSO3 such as Li3PSO3 3- and the peak area of PSO3 3- is less than 30%, preferably less than 25%, more preferably less than 20%, even more preferably less than 10%, and most preferably less than 5% of the total area, and is a solid sulfide electrolyte according to the present invention. The preferred embodiment is by NMR, preferably 31As measured by 31P NMR, it substantially does not contain a phase formed from PS2O2 such as Li3PS2O4, and the peak area of PS2O2 3- is less than 30% of the total area, preferably less than 25% of the total area, more preferably less than 20% of the total area, even more preferably less than 10% of the total area, and most preferably less than 5% of the total area, which is a solid sulfide electrolyte according to the present invention. A preferred embodiment is NMR, preferably 3- As measured by 31P NMR, it substantially does not contain a phase formed from P2S7, and the peak area of P2S7 31 is less than 30% of the total area, preferably less than 25% of the total area, more preferably less than 20% of the total area, even more preferably less than 10% of the total area, and most preferably less than 5% of the total area, which is a solid sulfide electrolyte according to the present invention. According to a preferred embodiment, the solid sulfide electrolyte according to the present invention has a purity of at least 70%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, and most preferably at least 95% as measured by NMR, preferably 4- As measured by 31P NMR. As is understood by those skilled in the art, PS4 4- has a signal of 80 to 90 ppm, preferably about 85 ppm as measured by 31P NMR, and PO4 31 has a signal of 5 to 15 ppm, preferably about 10 ppm as measured by 31P NMR, and PSO3 3- has a signal of 30 to 40 ppm, preferably about 35 ppm as measured by 31P NMR, and PS2O2 31 has a signal of 65 to 75 ppm, preferably about 70 ppm as measured by 31P NMR, and P2S7 3- has a signal of 90 to 100 ppm, preferably about 95 ppm as measured by 31P NMR. 31 has a signal of 5 to 15 ppm, preferably about 10 ppm as measured by 31P NMR, and PSO3 3- has a signal of 30 to 40 ppm, preferably about 35 ppm as measured by 31P NMR, and PS2O2 31 has a signal of 65 to 75 ppm, preferably about 70 ppm as measured by 31P NMR, and P2S7 3- has a signal of 65 to 75 ppm, preferably about 70 ppm as measured by 31P NMR, and P2S7 31 has a signal of 65 to 75 ppm, preferably about 70 ppm as measured by 31P NMR, and P2S7 4- has a signal of 90 to 100 ppm, preferably about 95 ppm as measured by 31P NMR. 31 has a signal of 90 to 100 ppm, preferably about 95 ppm as measured by 31P NMR.

[0070] A preferred embodiment is a solid sulfide electrolyte according to the present invention having an ionic conductivity of at least 1 mS / cm, preferably at least 1.5 mS / cm, and most preferably at least 2 mS / cm. A preferred embodiment is a solid sulfide electrolyte according to the present invention having an ionic conductivity of less than 5 mS / cm, more preferably less than 4 mS / cm, and most preferably less than 3 mS / cm. A preferred embodiment is a solid sulfide electrolyte according to the present invention having an ionic conductivity of 1 to 5 mS / cm, preferably 1.5 to 4 mS / cm, and most preferably 2 to 3 mS / cm.

[0071] A preferred embodiment is a solid sulfide electrolyte according to the present invention having an electronic conductivity of at least 1×10 -7 mS / cm, preferably at least 1×10 -6 mS / cm, and most preferably at least 1×10 -5 mS / cm. A preferred embodiment is a solid sulfide electrolyte according to the present invention having an electronic conductivity of less than 1×10 -2 mS / cm, preferably less than 1×10 -3 mS / cm, and most preferably less than 1×10 -4 mS / cm. A preferred embodiment is a solid sulfide electrolyte according to the present invention having an electronic conductivity of 1×10 -7 to 1×10 -2 mS / cm, preferably 1×10 -6 to 1×10 -3 mS / cm, and most preferably 1×10 -5 to 1×10 -4 mS / cm.

[0072] A third aspect of the present invention is to provide a solid sulfide electrolyte having a thiargyrite-type crystal structure. As will be understood by those skilled in the art, all embodiments relating to the method for manufacturing a solid sulfide electrolyte according to the present invention, and all embodiments relating to the solid sulfide electrolyte obtainable by the method for manufacturing a solid sulfide electrolyte, are equally applicable to the solid sulfide electrolyte having a thiargyrite-type crystal structure according to the present invention.

[0073] The preferred embodiment is substantially free of a phase formed from Li2S, LiCl, Li4P2S6 and / or Li3PS4, as measured by XRD, and the peak intensity of Li2S, LiCl, Li4P2S6 and / or Li3PS4 is less than 30%, preferably less than 25%, more preferably less than 20%, even more preferably less than 10%, and most preferably less than 5% of the peak intensity of Li6PS5Cl. It is a solid sulfide electrolyte according to the present invention. According to a preferred embodiment, the solid sulfide electrolyte according to the present invention has a purity of at least 70%, preferably at least 75%, more preferably at least 80%, even more preferably 90%, and most preferably at least 95%, as measured by XRD.

[0074] The preferred embodiment is a solid sulfide electrolyte according to the present invention having an XRD pattern near 2θ = 15.5 ± 1°, 18 ± 1°, 26 ± 1°, 30.5 ± 1° and 32 ± 1° using CuKα radiation.

[0075] The preferred embodiment is NMR, preferably 31 as measured by 31P NMR, substantially free of a phase formed from PO4 such as Li3PO4 3- and the peak area of PO4 3- is less than 30%, preferably less than 25%, more preferably less than 20%, even more preferably less than 10%, and most preferably less than 5% of the total area. It is a solid sulfide electrolyte according to the present invention. The preferred embodiment is NMR, preferably 31 as measured by 31P NMR, substantially free of a phase formed from PSO3 such as Li3PSO3 3- and the peak area of PSO3 3-The peak area of is less than 30% of the total area, preferably less than 25% of the total area, more preferably less than 20% of the total area, even more preferably less than 10% of the total area, and most preferably less than 5% of the total area, which is the solid sulfide electrolyte according to the present invention. A preferred embodiment is NMR, preferably 31 substantially free of a phase formed from PS2O2 such as Li3PS2O4, as measured by 31P NMR 3- The peak area of is less than 30% of the total area, preferably less than 25% of the total area, more preferably less than 20% of the total area, even more preferably less than 10% of the total area, and most preferably less than 5% of the total area, which is the solid sulfide electrolyte according to the present invention. A preferred embodiment is by NMR, preferably 3- substantially free of a phase formed from P2S7 as measured by 31P NMR 31 The peak area of is less than 30% of the total area, preferably less than 25% of the total area, more preferably less than 20% of the total area, even more preferably less than 10% of the total area, and most preferably less than 5% of the total area, which is the solid sulfide electrolyte according to the present invention. According to a preferred embodiment, the solid sulfide electrolyte according to the present invention has a purity of at least 70%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, and most preferably at least 95% as measured by NMR, preferably 4- substantially free of a phase formed from P2S7 4- The peak area of is less than 30% of the total area, preferably less than 25% of the total area, more preferably less than 20% of the total area, even more preferably less than 10% of the total area, and most preferably less than 5% of the total area, which is the solid sulfide electrolyte according to the present invention. According to a preferred embodiment, the solid sulfide electrolyte according to the present invention has a purity of at least 70%, preferably at least 75%, more preferably at least 80%, even more preferably at least 90%, and most preferably at least 95% as measured by NMR, preferably 31 31P NMR. As is understood by those skilled in the art, PS4 3- has a signal of 80 - 90 ppm, preferably about 85 ppm as measured by 31P NMR, and PO4 31 has a signal of 5 - 15 ppm, preferably about 10 ppm as measured by 31P NMR, and PSO3 3- has a signal of 30 - 40 ppm, preferably about 35 ppm as measured by 31P NMR, and PS2O2 31 has a signal of 30 - 40 ppm, preferably about 35 ppm as measured by 31P NMR, and PS2O2 3- has a signal of 30 - 40 ppm, preferably about 35 ppm as measured by 31P NMR, and PS2O2 31 has a signal of 30 - 40 ppm, preferably about 35 ppm as measured by 31P NMR, and PS2O23- has 31 a signal of 65 - 75 ppm, preferably about 70 ppm, as measured by ³¹P NMR, and is P₂S₇ 4- has 31 a signal of 90 - 100 ppm, preferably about 95 ppm, as measured by ³¹P NMR.

[0076] A preferred embodiment is a solid sulfide electrolyte according to the present invention having an ionic conductivity of at least 1 mS / cm, preferably at least 1.5 mS / cm, and most preferably at least 2 mS / cm. A preferred embodiment is a solid sulfide electrolyte according to the present invention having an ionic conductivity of less than 5 mS / cm, more preferably less than 4 mS / cm, and most preferably less than 3 mS / cm. A preferred embodiment is a solid sulfide electrolyte according to the present invention having an ionic conductivity of 1 - 5 mS / cm, preferably 1.5 - 4 mS / cm, and most preferably 2 - 3 mS / cm.

[0077] A preferred embodiment is a solid sulfide electrolyte according to the present invention having an electronic conductivity of at least 1×10 -7 mS / cm, preferably at least 1×10 -6 mS / cm, and most preferably at least 1×10 -5 mS / cm. A preferred embodiment is a solid sulfide electrolyte according to the present invention having an electronic conductivity of less than 1×10 -2 mS / cm, preferably less than 1×10 -3 mS / cm, and most preferably less than 1×10 -4 mS / cm. A preferred embodiment is a solid sulfide electrolyte according to the present invention having an electronic conductivity of 1×10 -7 - 1×10 -2 mS / cm, preferably 1×10 -6 - 1×10 -3 mS / cm, and most preferably 1×10 -5 - 1×10 -4 mS / cm.

[0078] Battery A fourth aspect of the present invention relates to a battery comprising a negative electrode, a positive electrode, and a solid electrolyte layer, wherein at least one of the cathode, anode, and solid electrolyte layer contains a solid sulfide electrolyte according to the present invention, for example, a solid sulfide electrolyte obtainable by the method according to the present invention, and / or a solid sulfide electrolyte having a thiargyrite-type crystal structure according to the present invention. The solid sulfide electrolyte of the present invention can be used as a solid electrolyte layer of a solid lithium-ion battery or a solid primary lithium battery, or as a solid electrolyte mixed with an electrode mixture of a positive electrode or a negative electrode.

[0079] As will be understood by those skilled in the art, the negative electrode is the anode and the positive electrode is the cathode. Thus, the present invention relates to a battery comprising a negative electrode, a positive electrode, and a solid electrolyte layer, wherein at least one of the positive electrode, negative electrode, and solid electrolyte layer contains a solid sulfide electrolyte according to the present invention.

[0080] In a preferred embodiment, the battery is a solid battery, preferably a lithium solid battery.

[0081] Use A fifth aspect of the present invention relates to the use of a solid sulfide electrolyte according to the present invention, for example, a solid sulfide electrolyte obtainable by the method according to the present invention and / or a solid sulfide electrolyte having a thiargyrite-type crystal structure according to the present invention, in a battery, preferably a solid battery, more preferably a lithium solid battery.

[0082] A sixth aspect of the present invention relates to the use of a battery according to the present invention in any one of a portable computer, a tablet, a mobile phone, an energy storage system, an electric vehicle, or a hybrid electric vehicle, preferably in an electric vehicle or a hybrid electric vehicle.

[0083] The present invention is further illustrated in the following examples.

Examples

[0084] Description of test method XRD analysis Crystallographic identification was carried out using a Bruker D8 Advanced diffractometer with Cu radiation (λ1 = 1.54056 Å, λ2 = 1.54439 Å). To prevent air exposure, a stainless-steel cell with a beryllium window was used.

[0085] Ionic conductivity Ionic conductivity was measured for pellet cells compressed with a pressure of 5 T on samples having a diameter of 10 mm and a total mass of 120 mg. The pellets were transferred to a plastic sleeve (diameter 10.2 mm) equipped with a stainless-steel plunger having carbon paper on both sides. 80 kg / cm 2 was applied to the plunger using a metal clamp and a torque wrench. Ionic conductivity was measured using an MTZ-35 impedance analyzer from Biologic at room temperature (25 °C) in the range of 1 Hz to 30 MHz using electrochemical impedance spectroscopy (EIS).

[0086] Electronic conductivity The electronic conductivity was measured by potentiostatic electrolysis at 25 °C for the same samples as the ionic conductivity by stepwise potentiostatic polarization at 0.2, 0.4, 0.6 V and 0.8 V.

[0087] NMR analysis NMR spectra were acquired in the temperature range of 100 - 300 K while rotating at a speed of 8 kHz using a Bruker 400 MHz (9.4 T) Ascend DNP-NMR spectrometer equipped with a 3.2 mm MAS DNP-NMR triple resonance broadband X / Y / H magic angle spinning (MAS) probe. At each temperature point, the sample temperature was calibrated using the T1 of 79Br in KBr. For (35)23Na measurements, the probe was tuned to 105.9 MHz and the zg experiment using a π / 2 pulse of 6 μs at 10 W was used to selectively excite the central transition. The recycle delay was set to 40 s. The 23Na spectra are reported relative to the chemical shift of a 1.0 M aqueous solution of NaCl set at 0 ppm. 31For the P spectrum, the probe was adjusted to 162.0 MHz, and a zg experiment with a π / 6 pulse of 1 μs at 160 W was used. The recycle delay was set to 200 seconds. 31 The P spectrum is reported relative to the chemical shift of solid triphenylphosphine set at -9 ppm. Quantification of the different phases was performed by fitting in Origin (pseudo Voigt), followed by calculating the phase percentage from the peak areas. Alternatively, 31 P measurements were carried out on a 500 MHz (11.7 T) WB (wide-bore) Bruker Avance NMR spectrometer for solids using a 2.5 mm dual resonance broadband probe rotating at 30 kHz. Experiments were conducted using a spin echo pulse program. Relaxation delays of 10 or 20 seconds were used depending on the sample.

[0088] Examples A precursor mixture containing lithium sulfide (Li2S, 0.1712 g), lithium chloride (LiCl, 0.1580 g), and lithium thiophosphate (Li3PS4, 0.6709 g) was prepared in a molar ratio of 1:1:1. This precursor mixture was placed in a glass container together with a liquid (20 mL). The total solid content was approximately 5% based on the total weight of the mixture. Table 1 shows all the tested liquids, their water contents measured by Karl Fischer titration, and the solubilities of LiCl, Li2S, Li3PS4, and Li6PS5Cl in these solvents, where "yes" means the corresponding compound is completely dissolved, "partially yes" means the corresponding compound is partially dissolved, and "no" means the corresponding compound is not dissolved. The resulting solution was stirred at 25 °C for 24 hours. Next, the solvent was removed by evaporation using a rotary evaporator. Then, the obtained mixture was further dried under vacuum by a stepwise temperature increase at 80 °C for 1 hour, 100 °C for 1 hour, and 150 °C for 18 hours. Figure 1 shows the XRD spectrum before firing. In CEX1, the formation of Li6PS5Cl was observed. In CEX2, only LiCl and Li2S were observed, and the formation of Li6PS5Cl was not observed. In EX1 - 5, the formation of Li6PS5Cl was not observed, and the beryllium peak (Be) was derived from the sample holder with a beryllium window. Then, the dried mixture was compressed into pellets and fired at 525 °C for 6 hours (heating time of 2 hours at 4.2 °C / min) in a stainless - steel autoclave equipped with an alumina crucible to obtain Li6PS5Cl. Table 2 shows the results of the ionic conductivity and electronic conductivity of each solvent. Figure 2 shows the XRD spectrum after firing, and Li6PS5Cl was observed for CEX1 - 2 and EX1 - 5. XRD analysis demonstrated that EX1 had 78.95% Li6PS5Cl, 4.78% Li2S, 1.75% LiCl, and the remaining decomposition products. EX3 had 71.46% Li6PS5Cl, 6.17% Li2S, 1.95% LiCl, and the remaining decomposition products.EX4 has 74.35% Li6PS5Cl, 5.82% Li2S, 1.80% LiCl and the remaining decomposition products, and EX5 has 77.83% Li6PS5Cl, 4.18% Li2S, 2.85% LiCl and the remaining decomposition products. Figure 3 shows the. 31 P NMR spectra. Quantification of the peak areas (see Table 3) shows that the reaction in EtOH before firing results in a larger amount of decomposition products, particularly decomposition products with PSO3 3- units, compared to DMF as a liquid. 31 P NMR analysis shows that fired EX1 has 98.7% PS4 3- units and 1.2% PO4 3- units.

[0089]

Table 1

[0090]

Table 2

[0091]

Table 3

Claims

1. The following successive steps are included: (i) Li ２ S, Li ３ PS ４ providing an electrolyte precursor mixture comprising a solid electrolyte precursor mixture containing Li, S, Li ２ , PS ３ and LiX (wherein X is a halogen selected from F, Cl, Br, I or a combination thereof), and a liquid containing no hydroxyl moiety (ii) mixing the electrolyte precursor mixture obtained in step (i); and (iii) heat-treating the mixed electrolyte precursor mixture obtained in step (ii) to obtain a solid sulfide electrolyte having a silverdorfer-germanite crystal structure.

2. The method of claim 1 , wherein the liquid that does not contain hydroxyl moieties is an organic liquid.

3. 3. The method of claim 1 or 2, wherein the liquid not containing hydroxyl moieties is selected from the group consisting of hydrocarbons, esters, ketones, aldehydes, ethers, nitriles, amines, amides, carbonates, sulfoxides, sulfones, sulfonates, thiols, fluoro-based compounds and combinations thereof, preferably selected from the group consisting of aromatic hydrocarbons, esters, ethers, nitriles, amides, sulfoxides, thiols and combinations thereof, more preferably selected from the group consisting of amides, esters, ethers, nitriles, aromatic hydrocarbons and combinations thereof.

4. Step (ii) further comprises the steps of: (ii) mixing the electrolyte precursor mixture obtained in step (i); and (ii)b) drying the mixed electrolyte precursor obtained in step (ii)a, thereby obtaining a solid electrolyte mixture.

5. The solid sulfide electrolyte is represented by the formula (I) Li ７－ｙ PS ６－ｙ X ｙ (I) is represented by In the formula, y is 0.8 to 1.7, preferably y is 0.9 or more and 1.6 or less, and more preferably y is 1.0 or more and 1.4 or less. The method for producing a solid sulfide electrolyte according to any one of claims 1 to 4.

6. The solid sulfide electrolyte is represented by the formula (II) Li ６ PS ５ X (II) The method for producing a solid sulfide electrolyte according to any one of claims 1 to 5, wherein

7. The method for producing a solid sulfide electrolyte according to any one of claims 1 to 6, wherein the mixing of the electrolyte precursor mixture is carried out for a mixing time of 1 hour to 72 hours, preferably 2 hours to 50 hours, more preferably 10 hours to 30 hours.

8. Li ２ S: Li ３ PS ４ : A method for producing a solid sulfide electrolyte according to any one of claims 1 to 7, wherein the molar ratio of LiX is 1:1:

1.

9. In the formula, X = Cl, Br, I or a combination thereof, more preferably X = Cl, Br or a combination thereof, and most preferably X = Cl. The method for producing a solid sulfide electrolyte according to any one of claims 1 to 8.

10. The method for producing a solid sulfide electrolyte according to any one of claims 1 to 9, wherein the heat treatment is carried out at a temperature of 100 to 1000°C, preferably 300 to 700°C, more preferably 350 to 650°C.

11. The method for producing a solid sulfide electrolyte according to any one of claims 1 to 10, wherein the heat treatment is carried out for 0.5 hours to 24 hours, preferably 1 hour to 12 hours, more preferably 1.5 hours to 10 hours.

12. A solid sulfide electrolyte obtainable by the method according to any one of claims 1 to 11.

13. A solid sulfide electrolyte having a thiargyrite-type crystal structure with a purity exceeding 70% as measured by XRD.

14. ３１ The solid sulfide electrolyte according to claim 13, having a purity of at least 95% as measured by P NMR.

15. Formula (I) Li ７－ｙ PS ６－ｙ X ｙ (I) represented by wherein y is 0.8 to 1.7, preferably y is 0.9 or more and 1.6 or less, more preferably y is 1.0 or more and 1.4 or less, the solid sulfide electrolyte according to claim 13 or 14.

16. A battery comprising a negative electrode, a positive electrode, and a solid electrolyte layer, wherein at least one of the positive electrode, the negative electrode, and the solid electrolyte layer contains the solid sulfide electrolyte according to any one of claims 12 to 15.

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