Heterovalent substituted argyrodite solid electrolytes

Abstract

This invention relates to heterovalent substituted argyrodite-type solid electrolytes. These solid electrolytes exhibit increased ionic conductivity.

Description

[Technical Field]

[0001] The present invention relates to a heterovalent substituted argyrodite-type solid electrolyte, a method for producing the solid electrolyte, and a battery containing the electrolyte. [Background technology]

[0002] The rapid advancements in the development of small, lightweight electronic products, electronic devices, communication devices, and similar items, coupled with the widespread emergence of the need for electric vehicles in relation to environmental concerns, have created a demand for improved performance in rechargeable batteries used as power sources for these products. Among these, lithium-ion batteries are attracting attention as high-performance batteries due to their high energy density and high reference electrode potential.

[0003] However, the electrolytes conventionally used in lithium-ion batteries are liquid electrolytes such as organic solvents. Therefore, safety problems such as electrolyte leakage and fire risks can occur continuously. Recently, solid-state batteries, which contain solid electrolytes instead of liquid electrolytes, have been developed to improve the safety aspects of lithium-ion batteries and have attracted much attention. For example, solid electrolytes are generally safer than liquid electrolytes due to their non-flammable or flame-retardant properties.

[0004] The solid electrolyte may include oxide-based solid electrolytes, polymer-based electrolytes, and sulfide-based electrolytes. For example, sulfide-based electrolytes, such as sulfide-based solid electrolytes having an argyrodite-type crystal structure, are commonly used because they have a wider lithium ion conductivity range compared to oxide-based and polymer-based solid electrolytes.

[0005] Minafra et al (J.Mater.Chem.A 2018,6,645-651) proposed the general formula Li 6+x P 1-x Si x The synthesis of solid electrolytes containing S5Br (0 ≤ x ≤ 0.5) is described, for example, Li 6.125 P 0.875 Si 0.125 S5Br and Li6.35 P 0.65 Si 0.35 Examples include S5Br.

[0006] Strauss et al (Inorg. Chem. 2020, 59, 12954 - 12959) describe the synthesis of Li7GeS5Br with an argyrodite structure.

[0007] An object of the present invention is to provide a hetero - valence - substituted argyrodite - type solid electrolyte.

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

[0009] A further object of the present invention is to provide a battery containing the solid electrolyte.

Summary of the Invention

[0010] In a first aspect, the object of the present invention is achieved by providing a solid electrolyte having a composition according to formula (I): Li 7-a YS 5-a X 1+a (I) (where - 1.0 ≤ a ≤ - 1.0, Y is selected from the group consisting of Si, Ge, and Ti, X is selected from the group consisting of F, Cl, Br, I, and any combination thereof).

[0011] A highly preferred embodiment is the solid electrolyte of the present invention, provided that when Y = Ge and a = 0, X ≠ Br.

[0012] In a specific preferred embodiment, the solid electrolyte has the formula (II) Li 7-b YS<00000l4>ZQ b (II) (where 0 < b ≤ 1.0, Y is selected from the group consisting of Si, Ge, and Ti, Z is selected from the group consisting of F, Cl, Br, and I. Q is selected from the group consisting of F, Cl, Br, and I. The present invention provides a solid electrolyte having a composition in which Z and Q are not the same halogen.

[0013] The inventors have surprisingly found that heterovalent substituted argyrodite-type solid electrolyte compositions exhibit a maximum emission of 2 mS.cm, as shown in the attached examples. -1 We found that this exhibits an increase in ionic conductivity.

[0014] While we do not wish to be bound by any theory, the inventors believe that heterovalence substitution of P with Si, Ge, or Ti leads to expansion of the unit cell and the inclusion of additional lithium cations within the structure. Furthermore, halide substitution is X - / S 2- This results in increased irregularity of the site. Therefore, by modifying the structure, the lithium content increases, ionic interactions increase, and this leads to an improvement in ionic conductivity, as shown in the attached examples. Furthermore, these observations support the two indicators E hull (Energy on the outer shell) and E mig This was supported by computational modeling focused on predicting the lithium diffusion rate into the argyrodite structure based on (transfer energy barrier). hull This identifies the stability of specific argyrodite compounds, while E mig This is a predictor of ionic conductivity.

[0015] In a further embodiment, the present invention provides a method for producing the solid electrolyte.

[0016] In a further embodiment, the present invention provides a battery comprising a solid electrolyte according to the present invention. [Brief explanation of the drawing]

[0017] [Figure 1]X-ray diffraction patterns of Li7SiS5I, Li7SiS5Br, and Li7SiS5Cl recorded at 298K in a dome-shaped airtight specimen holder made by Bruker. [Figure 2] X-ray diffraction patterns of Li7.5SiS4.5I0.5 and Li7SiS5I recorded at 298K in a dome-shaped airtight specimen holder made by Bruker. [Figure 3] X-ray diffraction patterns of Li6.5SiS4.5Br0.5I and Li6.5SiS4.5BrI0.5, recorded at 298K in a dome-shaped airtight specimen holder made by Bruker. [Modes for carrying out the invention]

[0018] Detailed explanation The drawings and the following detailed description illustrate in detail preferred embodiments for enabling the implementation of the present invention. While the present invention is described with reference to these particular preferred embodiments, it will be understood that the present invention is not limited to these preferred embodiments. Conversely, the present invention includes numerous alternatives, variations, and equivalents, which will become apparent by considering the following detailed description and the accompanying drawings.

[0019] As used herein and in the claims, the term “comprising” should not be construed as limiting to the means listed thereafter, nor as excluding other elements or processes. It should be construed as specifying the presence of the described features, integers, processes, or components mentioned, but not as precluding the presence or addition of one or more other features, integers, processes, or components, or groups thereof. Accordingly, the expression “composition comprising components A and B” should not be limited to a composition consisting solely of components A and B. This means that, with respect to the present invention, A and B are merely components that are relevant in the composition. Thus, the terms “comprising” and “including” encompass the more restrictive terms “consisting essentially of” and “consisting of.”

[0020] As used herein, the term “solid-state battery” refers to a cell or battery that comprises only solid or substantially solid components, such as solid electrodes (e.g., anode and cathode) and solid electrolyte.

[0021] As used in this disclosure, the term “argyrodite crystal structure” refers to a crystal structure having a crystal structure or system similar to the naturally occurring Ag8GeS6 and Li7PS6 (argyrodites). The argyrodite crystal structure may be orthorhombic and may be described in the F-43m space group. In some embodiments, the argyrodite crystal structure can also be empirically measured by X-ray diffraction, for example, by observing diffraction peaks at 2θ = 15.5±1°, 18±1°, 26±1°, 30.5±1°, and 32±1° using CuKα wavelengths. X-ray diffraction (XRD) as referred to in this disclosure refers to XRD experiments performed using a Bruker D8 diffractometer equipped with θ-θ arranged Cu(Kα1-Kα2) radiation. Preferably, an airtight sample holder dome window from Bruker (transparent to X-ray) is used. The pattern is preferably measured with a step size of 0.02° for 2θ = 10° to 50°.

[0022] Unless otherwise stated, the ionic conductivity referred to in this disclosure refers to the ionic conductivity measured at 23°C. This is preferably measured on a cold-pressed sample in a 13 mm die at 375 MPa using a Biologic CESH cell, and the spectrum was recorded using an MTZ 35 frequency response analyzer by applying a 50 mV AC perturbation in the frequency range of 7 MHz to 1 Hz. Preferably, the relative density of the pellet is 90 to 92%, and the thickness is approximately 2.5 mm. Preferably, nickel foil is pressed onto the surface of the pellet as an ion-blocking electrode. More preferably, the spectrum was collected in a temperature range of 23°C in 10°C increments.

[0023] As used in this disclosure, the term “solid electrolyte” means an electrolyte that is essentially free of any liquid. The term “essentially free of liquid” means that the solid electrolyte contains less than 10% by weight of liquid relative to the total weight of the solid electrolyte, 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, relative to the total weight of the solid electrolyte. In more preferred embodiments, the solid electrolyte contains less than 1000 ppm of liquid relative to the total weight of the solid electrolyte, 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, relative to the total weight of the solid electrolyte.

[0024] solid electrolyte

[0025] In the first aspect, the object of the present invention is formula (I) Li 7-a YS 5-a X 1+a (I) (In the formula, -1.0 ≤ a ≤ 1.0, Y is selected from the group consisting of Si, Ge, and Ti. This is achieved by providing a solid electrolyte having a composition of X, which is selected from the group consisting of F, Cl, Br, I, and any combination thereof.

[0026] A very preferred embodiment is the solid electrolyte according to the present invention, where Y=Ge and a=0, and X≠Br.

[0027] In certain more preferred embodiments, the solid electrolyte of the present invention is a solid electrolyte of formula (I)' Li7GeS5X (I)' Provided that (wherein X is selected from the group consisting of F, Cl, Br, I, and any combination thereof) it is not due to

[0028] In a preferred embodiment, the solid electrolyte has a range of -0.99 ≤ a ≤ 0.99, preferably -0.95 ≤ a ≤ 0.95, more preferably -0.75 ≤ a ≤ 0.75, and most preferably -0.5 ≤ a ≤ 0.5, according to the present invention.

[0029] In a preferred embodiment, the solid electrolyte is a = -0.5, 0, or 0.5, and more preferably a = 0.5, according to the present invention.

[0030] In certain preferred embodiments, the solid electrolyte Y is Si, Ge, or Ti, preferably Y is Si or Ge, or preferably Y is Si or Ti, and more preferably Y is Si, according to the present invention.

[0031] In certain preferred embodiments, the solid electrolyte is Cl, Br, I, or a combination thereof, preferably X is Br, I, or a combination thereof, and more preferably X is Br or I, according to the present invention.

[0032] In certain preferred embodiments, the solid electrolyte is F, Cl, Br, or I, preferably X is Cl, Br, or I, more preferably X is Br or I, and most preferably X is I, according to the present invention.

[0033] According to a preferred embodiment of the present invention, a solid electrolyte is provided 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.

[0034] A preferred embodiment of the present invention provides a solid electrolyte in which X represents F, Cl, Br, I, or a combination thereof, and at least 50 mol% of X represents F, preferably at least 80 mol% of X represents F.

[0035] According to a preferred embodiment of the present invention, a solid electrolyte is provided 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.

[0036] A preferred embodiment of the present invention provides a solid 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.

[0037] According to a preferred embodiment of the present invention, a solid electrolyte is provided 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.

[0038] A preferred embodiment of the present invention provides a solid 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.

[0039] According to a preferred embodiment of the present invention, a solid electrolyte is provided 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.

[0040] A preferred embodiment of the present invention provides a solid 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.

[0041] In certain preferred embodiments, the solid electrolyte is Y is Si, X is Cl, The present invention relates to a condition where -0.5 ≤ a ≤ 0.5, preferably -0.5 ≤ a ≤ 0, and more preferably a = 0 or 0.5.

[0042] In certain preferred embodiments, the solid electrolyte is Y is Si, X is Br, The present invention relates to a condition where -0.5 ≤ a ≤ 0.5, preferably a = -0.5, 0, or 0.5, and more preferably a = -0.5 or 0.5.

[0043] In certain preferred embodiments, the solid electrolyte is Y is Si, X is I, The present invention relates to a condition where -0.5 ≤ a ≤ 0.5, preferably a = -0.5, 0, or 0.5, and more preferably a = 0.5.

[0044] In a more preferred embodiment, the solid electrolyte is provided according to the present invention, and the solid electrolyte is provided by formula (I)a to i: [Table 1]

[0045] In a preferred embodiment, the solid electrolyte is a powder.

[0046] In a preferred embodiment, the solid electrolyte of the present invention has an argyrodite-type crystal structure.

[0047] In a preferred embodiment, the solid electrolyte has a molar ratio of Li:Y:S:X of (5-8):(0.9-1.1):(4-6):(0.1-1.9), preferably (6.5-7.5):(0.99-1.01):(4.5-5.5):(0.5-1.5), and more preferably (6.5):(1.0):(4.5):(1.5) or (7.0):(1.0):(5.0):(1.0) or (7.5):(1.0):(4.5):(0.5), according to the present invention.

[0048] In a preferred embodiment, the solid electrolyte according to the present invention has a purity of at least 90%, preferably at least 95%, and more preferably at least 99%, as measured by XRD.

[0049] In a preferred embodiment, the solid electrolyte according to the present invention has an electrical conductivity of 0.1 to 5 mS / cm, preferably 0.5 to 3.5 mS / cm, and more preferably 1 to 2.5 mS / cm.

[0050] In certain preferred embodiments, the solid electrolyte of the present invention is according to formula (I)a and has an conductivity of preferably 0.5 to 1.5 mS / cm, more preferably 0.75 to 1.25 mS / cm, and most preferably about 1.1 mS / cm.

[0051] In certain preferred embodiments, the solid electrolyte of the present invention is according to formula (I)b and has an conductivity of preferably 0.5 to 1.5 mS / cm, more preferably 0.75 to 1.25 mS / cm, and most preferably about 1.0 mS / cm.

[0052] In certain preferred embodiments, the solid electrolyte of the present invention is according to formula (I)d and has an conductivity of preferably 1.0 to 2.0 mS / cm, more preferably 1.25 to 1.75 mS / cm, and most preferably about 1.5 mS / cm.

[0053] In certain preferred embodiments, the solid electrolyte of the present invention is according to formula (I)e and preferably has a conductivity of 1.0 to 2.0 mS / cm, more preferably 1.25 to 1.75 mS / cm, and most preferably about 1.3 mS / cm.

[0054] In certain preferred embodiments, the solid electrolyte of the present invention is according to formula (I)f and preferably has a conductivity of 1.0 to 2.0 mS / cm, more preferably 1.25 to 1.75 mS / cm, and most preferably about 1.5 mS / cm.

[0055] In certain preferred embodiments, the solid electrolyte of the present invention is according to formula (I)g and has an conductivity of preferably 1.0 to 2.5 mS / cm, more preferably 1.50 to 2.0 mS / cm, and most preferably about 1.7 mS / cm.

[0056] In certain preferred embodiments, the solid electrolyte of the present invention is according to formula (I)h and has an conductivity of preferably 1.0 to 2.5 mS / cm, more preferably 1.50 to 2.0 mS / cm, and most preferably about 1.7 mS / cm.

[0057] In certain preferred embodiments, the solid electrolyte of the present invention is according to formula (I)i and preferably has a conductivity of 1.0 to 2.5 mS / cm, more preferably 1.50 to 2.0 mS / cm, and most preferably about 1.8 mS / cm.

[0058] In certain preferred embodiments, the solid electrolyte is of formula (II) Li 7-b YS 5-b ZQ b (II) (In the formula, 0 <b≦1.0であり、 Y is selected from the group consisting of Si, Ge, and Ti. Z is selected from the group consisting of F, Cl, Br, and I. Q is selected from the group consisting of F, Cl, Br, and I. The present invention relates to a composition having Z and Q (where Z and Q are not the same halogen).

[0059] In a preferred embodiment, the solid electrolyte is given by formula (II), where 0.01 ≤ b < 0.99, preferably 0.25 ≤ b ≤ 0.75, more preferably 0.4 ≤ b ≤ 0.6, and most preferably b is about 0.5.

[0060] In a preferred embodiment, the solid electrolyte is given by formula (II), where Y is Si, Ge, or Ti, preferably Y is Si or Ge, or preferably Y is Si or Ti, and more preferably Y is Si.

[0061] In a preferred embodiment, the solid electrolyte is given by formula (II), where Z is Cl, Br, or I, preferably Br or I.

[0062] In a preferred embodiment, the solid electrolyte is given by formula (II), where Q is Cl, Br, or I, preferably Br or I.

[0063] In certain preferred embodiments, the solid electrolyte conforms to formula (II), where, Y is Si, Z is Br, Q is I, • 0.25 ≤ b ≤ 0.75, more preferably 0.4 ≤ b ≤ 0.6, and most preferably b is about 0.5.

[0064] In certain preferred embodiments, the solid electrolyte conforms to formula (II), where, Y is Si, Z is I, Q is Br, • 0.25 ≤ b ≤ 0.75, more preferably 0.4 ≤ b ≤ 0.6, and most preferably b is about 0.5.

[0065] In a more preferred embodiment, the solid electrolyte conforms to the present invention, and the solid electrolyte conforms to formula (II)a-b: [Table 2]

[0066] In a preferred embodiment, the solid electrolyte is of formula (II) having an argyrodite-type crystal structure.

[0067] In a preferred embodiment, the solid electrolyte is given by formula (II), where the molar ratio of Li:Y:S:Z:Q is between (5-8):(0.9-1.1):(4-6):(0.1-1.5):(0.1-1.5), preferably (6.5-7.5):(0.99-1.01):(4.5-5.5):(0.5-1.0):(0.5-1.0), more preferably (6.5):(1.0):(4.5):(0.5):(1.0) or (6.5):(1.0):(4.5):(1.0):(0.5) or (7.0):(1.0):(5.0):(0.5):(0.5).

[0068] In a preferred embodiment, the solid electrolyte is of formula (II) having a purity of at least 90%, preferably at least 95%, and more preferably at least 99%, as measured by XRD.

[0069] In a preferred embodiment, the solid electrolyte is based on formula (II) and has an electrical conductivity of 0.1 to 5 mS / cm, preferably 0.5 to 3.5 mS / cm, and more preferably 1 to 2.5 mS / cm.

[0070] In certain preferred embodiments, the solid electrolyte of the present invention is according to formula (II)a and has an conductivity of preferably 1.5 to 2.5 mS / cm, more preferably 2.0 to 2.5 mS / cm, and most preferably about 2.4 mS / cm.

[0071] In certain preferred embodiments, the solid electrolyte of the present invention is according to formula (II)b and has an conductivity of preferably 1.5 to 2.5 mS / cm, more preferably 2.0 to 2.5 mS / cm, and most preferably about 2.1 mS / cm.

[0072] Manufacturing method

[0073] In a second aspect, the present invention provides a method for producing a solid electrolyte, and this production method is a) A step of providing a set of precursors including Li, S, Y, and X, b) A step of mixing a set of precursors to obtain a solid electrolyte mixture, c) The process includes a step of heat-treating a solid electrolyte mixture to obtain a solid electrolyte, Y is selected from the group consisting of Si, Ge, and Ti. X is selected from the group consisting of F, Cl, Br, and I, preferably Cl, Br, or I, more preferably Br or I, and most preferably I.

[0074] In a preferred embodiment of the method, X consists of Z and Q, Z is selected from the group consisting of F, Cl, Br, and I, preferably Cl, Br, or I, and more preferably Br or I. Q is selected from the group consisting of F, Cl, Br, and I, preferably Cl, Br, or I, and more preferably Br or I. Z and Q are not the same halogen.

[0075] In a very preferred embodiment, the method is as described by the present invention, wherein the set of precursors comprises Li2S, one or more from the group consisting of Si2S, Ge2S, and Ti2S, preferably Si2S, and one or more from the group consisting of LiI, LiBr, and LiCl.

[0076] In a very preferred embodiment, the method is according to the present invention, wherein the solid electrolyte is a solid electrolyte according to the first aspect of the present invention, preferably a solid electrolyte according to formula (I) and / or formula (II), and preferably formula (I)a to i and / or formula (II)a to b.

[0077] As will be understood by those skilled in the art, all embodiments relating to solid electrolytes according to the first aspect of the present invention are applicable mutatis mutandis to the present method for producing solid electrolytes according to the present invention. For example, the various embodiments relating to formulas (I), (II), purity levels, and conductivity levels described herein with respect to solid electrolytes are also applicable to the method for producing solid electrolytes according to the present invention.

[0078] In a preferred embodiment, the method is as described in the present invention, and the mixing of the solid electrolyte precursor in step b) may include mixing, grinding, stirring, ball mill grinding, or a combination thereof.

[0079] In a preferred embodiment, the method according to the present invention mixes the set of precursors from step b) at a mixing speed of at least 100 rpm, preferably at least 300 rpm, and most preferably at least 400 rpm. In a preferred embodiment, the method according to the present invention mixes the set of precursors from step b) at a mixing speed of up to 1000 rpm, preferably up to 900 rpm, and most preferably up to 800 rpm. In a preferred embodiment, the method according to the present invention mixes the set of precursors from step b) at a mixing speed of 100 to 1000 rpm, preferably 300 to 900 rpm, and most preferably 400 to 800 rpm.

[0080] In a particular preferred embodiment, the mixing of the set of precursors in step b) is carried out by using a ball mill such as an electric ball mill, vibratory ball mill, planetary ball mill, vibratory mixer mill or SPEX mill, a bead mill, a homogenizer, a screw mixer, a horizontal mixer, and a mixing means such as a pull shear mixer, a jar mill, a drum mill or a roller bench. In a more preferred embodiment, the mixing of the set of precursors in step b) is carried out by adding one or more ceramic or zirconia balls to the set of precursors. As will be understood by those skilled in the art, the amount and size of the ceramic or zirconia balls are varied in consideration of the total solid content of the set of precursors. As will be understood by those skilled in the art, these ceramic or zirconia balls are removed before the heat treatment step c).

[0081] In a preferred embodiment, the method is according to the present invention, and the mixing of the precursor set in step b) is at least 1 hour, preferably at least 5 hours, and most preferably at least 10 hours. In a preferred embodiment, the method is according to the present invention, and the mixing of the precursor set in step b) is up to 70 hours, preferably up to 50 hours, and most preferably up to 30 hours. In a preferred embodiment, the method is according to the present invention, and the mixing of the precursor set in step b) is 1 to 70 hours, preferably 5 to 50 hours, and most preferably 10 to 30 hours.

[0082] In a preferred embodiment, the method is in accordance with the present invention, and the mixing of the solid electrolyte precursor mixture in step b) is carried out at a temperature of at least 5°C, preferably at least 10°C, and more preferably at least 15°C. In a preferred embodiment, the method is in accordance with the present invention, and the mixing of the solid electrolyte precursor mixture in step b) is carried out at a temperature of less than 50°C, preferably less than 40°C, and more preferably less than 30°C. In a preferred embodiment, the method is in accordance with the present invention, and the mixing of the solid electrolyte precursor mixture in step b) is carried out at a temperature of 5 to 50°C, preferably 10 to 40°C, and more preferably 15 to 30°C.

[0083] In certain preferred embodiments, the method is as described in the present invention, and the mixing of the solid electrolyte precursor in step b) is • Mixing time of 1 to 70 hours, preferably 5 to 50 hours, most preferably 10 to 30 hours. The mixing is carried out at a mixing speed of 100 to 1000 rpm, preferably 300 to 900 rpm, and most preferably 400 to 800 rpm.

[0084] In a preferred embodiment, the method is according to the present invention, and the heat treatment of the solid electrolyte mixture in step c) is carried out at a temperature of at least 100°C, preferably at least 150°C, more preferably at least 200°C, even more preferably at least 250°C, and most preferably at least 300°C. In a preferred embodiment, the method is according to the present invention, and the heat treatment of the solid electrolyte mixture in step c) is carried out at a temperature of less than 1000°C, preferably less than 900°C, more preferably less than 750°C, even more preferably less than 600°C, and most preferably less than 500°C. In a preferred embodiment, the method is according to the present invention, and the heat treatment of the solid electrolyte mixture in step c) is carried out at a temperature of 100 to 1000°C, preferably 200 to 750°C, and most preferably 250 to 450°C.

[0085] In a preferred embodiment, the method is according to the present invention, and the heat treatment of the solid electrolyte mixture in step c) 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. In a preferred embodiment, the method is according to the present invention, and the heat treatment of the solid electrolyte mixture in step c) is less than 24 hours, preferably less than 12 hours, more preferably less than 10 hours, even more preferably less than 8 hours, and even more preferably less than 6 hours. In a preferred embodiment, the method is according to the present invention, and the heat treatment of the solid electrolyte mixture in step c) is 0.5 hours to 24 hours, preferably 1 hour to 12 hours, and more preferably 2 hours to 6 hours.

[0086] In certain preferred embodiments, the method is according to the present invention, and the heat treatment of the solid electrolyte mixture in step c) is • At a temperature of 100 to 1000°C, preferably 200 to 750°C, most preferably 250 to 450°C, This process is carried out for 0.5 to 24 hours, preferably 1 to 12 hours, and most preferably 2 to 6 hours.

[0087] Product-by-process

[0088] In a third aspect, the present invention relates to a solid electrolyte obtainable by a method according to a second aspect of the present invention.

[0089] As will be understood by those skilled in the art, all embodiments relating to solid electrolytes according to the first aspect of the present invention and / or methods according to the second aspect of the present invention are applicable mutatis mutandis to solid electrolytes obtainable by the methods according to the present invention. For example, the various embodiments relating to formula (I), formula (II), purity levels, and conductivity levels described herein in the context of solid electrolytes are equally applicable to solid electrolytes obtainable by methods for producing solid electrolytes.

[0090] battery

[0091] 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 positive electrode, negative electrode, and solid electrolyte layer contains the solid electrolyte according to the present invention. The solid electrolyte of the present invention can be used as a solid electrolyte layer of a solid lithium-ion battery or a solid lithium primary battery, or as a solid electrolyte mixed with an electrode mixture of a positive electrode or a negative electrode.

[0092] In a preferred embodiment, the battery is a solid-state battery, preferably a lithium solid-state battery.

[0093] use

[0094] A fifth aspect of the present invention relates to the use of a solid electrolyte according to the present invention in a battery, preferably a solid-state battery, most preferably a lithium solid-state battery.

[0095] A sixth aspect of the present invention relates to the use of a battery according to the present invention in one of the following: a portable computer, a tablet, a mobile phone, an energy storage system, an electric vehicle, or a hybrid electric vehicle, preferably in a vehicle or a hybrid electric vehicle.

[0096] The present invention is further illustrated in the following embodiments. [Examples]

[0097] Explanation of the test method

[0098] Computation protocol

[0099] The computational models are, respectively, E hull (Energy on the outer shell) and E mig Based on the (transfer energy barrier), we focus on predicting thermodynamic stability and the lithium diffusion rate into the argyrodite structure.

[0100] E hull This is an important indicator for identifying the relative stability of a phase compared to other phases present in the multi-component phase diagram of a combination element. For example, to determine the phase stability of an argyrodite compound, it is necessary to calculate the energies of all known phases in the Li-PS-Cl chemical space and construct a phase diagram. A standard calculation method is to construct the convex outer shell of the multi-component phase diagram at 0K. Then, the energy of each phase is calculated relative to the energy of the convex hull, which is considered to be 0, and "E hull It is called "E". Therefore, E hull A higher value indicates that the compound is located on the convex outer layer of the most stable phase and has lower thermodynamic stability. This parameter is used to rank the most stable compounds and indicate the most likely to be synthesizable.

[0101] During charging and discharging, lithium ions move from one stable site to another by overcoming energy barriers and traversing the potential energy environment. The height of these energy barriers is calculated from the length of the bond (R, calculated from the shape). A-X ) where A and X are lithium ions and their adjacent atoms, and their intensity (s A-X It is estimated by the valence method related to ). The relationship is given by the following equation. s A-X =exp[(R0-R A-X / b )] In the equation, R0 and b are empirical valence (BO) parameters. This relationship allows their valences V(A) = Σxs A-X The sum of these values ​​is the ideal valence (oxidation state) of the lithium ion, V. ideal As the closest position, we can find the accessible position of the mobile lithium ion within the local structure of the electrolyte. The lowest energy path is the sum deviation of valence |V (A) -V ideal(A) | is the minimum, and the corresponding energy barrier is the minimum transfer energy barrier for lithium ions to diffuse in the electrolyte. Transfer energy barrier (E mig The lower the (E) value, the higher the lithium ion diffusion rate and the higher the ionic conductivity of the electrolyte. Therefore, mig This is an index of ionic conductivity used to rank promising candidates. Transfer energy was evaluated using the code BOND_STR, distributed within the FullProf package of the CrysFML library.

[0102] Synthesis protocol

[0103] All synthesis and sample processing were performed in an Ar-filled glove box with O2 and H2O levels <0.1 ppm. The stoichiometric ratios of the reagents, Li2S(Albemarle, 99.9%), SiS2(LTS US, 99%), LiCl(Sigma Aldrich, 99.98%), and / or LiBr(Sigma Aldrich, 99%), and / or LiI(Sigma Aldrich, 99.9%) were weighed to obtain 15 g batches of precursor. The precursor was transferred to a Restch PM 100 using a 250 mL zirconia ball milling jar with 16 zirconia balls with a diameter of 20 mm (ball:powder ratio was 30:1). The precursor was first ground at 100 rpm for 60 minutes to homogenize the mixture, followed by ball milling at 510 rpm for a total of 25 hours. Each cycle consisted of 5 minutes of grinding followed by 5 minutes of rest, with the grinding direction reversed for each cycle. At the end of the ball milling process, approximately 96% by weight of the material was recovered. The ball-milled powder was placed in a dry quartz tube, sealed under an argon atmosphere, and then placed in a furnace (Nabertherm) for heat treatment. The furnace temperature was slowly increased to 300°C at a ramp rate of 2°C / min and held for 2 hours, then allowed to cool naturally to room temperature. The reacted powder was then ground using a mortar and pestle and stored in a glove box for further analysis.

[0104] X-ray diffraction

[0105] Powder X-ray diffraction patterns were collected and measured using a Bruker D8 diffractometer equipped with θ-θ arranged Cu(Kα1-Kα2) radiation. A dome-shaped, airtight sample holder was used for the measurements. The patterns were measured in the range of 2θ = 10° to 50° with a step size of 0.02°.

[0106] Ionic conductivity measurement

[0107] Approximately 500 mg of sample was uniaxially cold-rolled at 375 MPa using a 13 mm die. The relative density of the pellets was 90–92%, and the thickness was approximately 2.5 mm. AC impedance spectroscopy was performed on these pellets by attaching a spectroscopy probe to the pellets in a pouch cell, applying a 50 mV AC disturbance in the frequency range of 7 MHz to 1 Hz, and recording the spectrum using a Biologic analyzer. The spectra were collected at 23°C. The AC impedance data was analyzed using Zview or RelaxIS software.

[0108] Examples

[0109] Table 1 shows the E of a series of solid electrolyte compatibility formulas (I). hull and E mig This indicates. [Table 3]

[0110] Table 2 shows the complete formula for an example synthesized by a general synthesis protocol, the corresponding measured ionic conductivity, and E. hull and E mig This indicates. [Table 4]

[0111] Profile matching of powder X-ray diffraction data suggests that the argyrodite structure is retained for samples Examples 2, 4, and 7 (Figure 1), Examples 6 and 7 (Figure 2), and Examples 9 and 10 (Figure 3), and no peaks corresponding to precursor or other impurity phases are observed.

Claims

1. Equation (I) Li ７－ａ YS ５－ａ X １＋ａ (I) (In the formula, -1.0 ≤ a ≤ 1.0, Y is selected from the group consisting of Si, Ge, and Ti. X is selected from the group consisting of F, Cl, Br, I, and any combination thereof. However, a solid electrolyte having a composition in which Y=Ge and a=0, X≠Br, The aforementioned solid electrolyte is given by formula (II) Li ７－ｂ 93 ５－ｂ ZQ ｂ (99) (In the formula, 0 < b ≤ 1.0, Y is selected from the group consisting of Si, Ge, and Ti. Z is selected from the group consisting of F, Cl, Br, and I. Q is selected from the group consisting of F, Cl, Br, and I. A solid electrolyte having a composition in which Z and Q are not the same halogen.

2. The solid electrolyte according to claim 1, wherein -0.99 ≤ a ≤ 0.99, preferably -0.75 ≤ a ≤ 0.75, more preferably -0.5 ≤ a ≤ 0.5, and most preferably a = -0.5, 0, 0.

5.

3. The solid electrolyte according to claim 1 or 2, wherein Y is Si or Ge, preferably Si.

4. A solid electrolyte according to any one of claims 1 to 3, wherein b is 0.01 ≤ b ≤ 0.99, preferably 0.25 ≤ b ≤ 0.75, more preferably 0.4 ≤ b ≤ 0.6, and most preferably b is about 0.

5.

5. The solid electrolyte according to any one of claims 1 to 4, wherein Y is Si or Ge, preferably Y is Si.

6. The solid electrolyte according to any one of claims 1 to 5, wherein Z is Cl, Br, or I, preferably Br or I.

7. The solid electrolyte according to any one of claims 1 to 6, wherein Q is Cl, Br, or I, preferably Br or I.

8. A solid electrolyte according to any one of claims 1 to 7, comprising a composition according to formula (II) a to b. Table 1

9. A solid electrolyte according to any one of claims 1 to 8, having an ionic conductivity of 0.1 to 5 mS / cm, preferably 0.5 to 2.5 mS / cm, and more preferably 1 to 2 mS / cm.

10. A method for producing a solid electrolyte, preferably the method described in any one of claims 1 to 9, a) A step of providing a set of precursors including Li, S, Y, and X, b) A step of mixing the set of precursors to obtain a solid electrolyte mixture, c) A manufacturing method comprising the step of heat-treating the solid electrolyte mixture to obtain a solid electrolyte. (In the formula, Y is selected from the group consisting of Si, Ge, and Ti, X is selected from the group consisting of F, Cl, Br, I and combinations thereof, preferably X is F, Cl, Br, or I, more preferably X is Cl, Br, or I, even more preferably X is Br or I, and most preferably X is I.

11. X consists of Z and Q, Z is selected from the group consisting of Cl, Br, and I, preferably Br or I, and more preferably I. Q is selected from the group consisting of Cl, Br, and I, preferably Br or I, and more preferably Br. The manufacturing method according to claim 10, wherein Z and Q are not the same halogen.

12. 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 electrolyte described in any one of claims 1 to 9.

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