Isovalently substituted argyrodite-type solid electrolyte

Abstract

The present invention relates to an isovalently substituted argyrodite-type solid electrolyte. These solid electrolytes exhibit increased ionic conductivity.

Description

[0001] TECHNICAL FIELD AND BACKGROUND The present invention relates to a heterovalently substituted argyrodite-type solid electrolyte, a method for manufacturing the same, and a battery comprising the same.

[0002] With the rapid development of small and light electronic products, electronic devices, communication devices, etc., and the demand for electric vehicles in terms of environmental problems has emerged widely, it is necessary to improve the performance of secondary batteries used as power sources for these products. Among them, lithium secondary batteries have become the focus as high-performance batteries due to high energy density and high reference electrode potential.

[0003] However, the electrolyte conventionally used in lithium secondary batteries is a liquid electrolyte such as an organic solvent. Therefore, safety problems such as electrolyte leakage and fire risk can occur continuously. Recently, solid-state batteries including solid electrolytes rather than liquid electrolytes are being developed to improve the safety features of lithium secondary batteries, and have attracted widespread attention. For example, solid electrolytes are generally safer than liquid electrolytes due to non-flammable or flame-retardant properties.

[0004] Solid electrolytes can include oxide-based solid electrolytes, polymer-based electrolytes, and sulfide-based electrolytes. Compared to oxide-based solid electrolytes and polymer-based solid electrolytes, sulfide-based electrolytes are commonly used due to their higher range of lithium ion conductivity, such as sulfide-based solid electrolytes having an argyrodite-type crystal structure.

[0005] Minafra KIM ET AL. (J. Mater. Chem. A 2018, 6, 645 651) describes the synthesis of solid electrolytes having the general formula wherein 0 ≤ x ≤ 0.5, such as and .

[0006] Strauss KIM ET AL. (Inorg. Chem. 2020, 59, 12954-12959) describes the synthesis of having an argyrodite structure.

[0007] It is an object of the present invention to provide a heterovalently substituted argyrodite-type solid electrolyte.

[0008] It is another object of the present invention to provide a method for manufacturing the same.

[0009] It is another object of the present invention to provide a battery comprising the same. SUMMARY

[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). (I) Where -1.0 ≤ a ≤ 1.0, Y is selected from the group consisting of Si, Ge, and Ti, and 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 X ≠ Br when Y = Ge and a = 0.

[0012] In some preferred embodiments, the solid electrolyte according to the invention has a composition according to formula (II). (II) , of which 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 selects a group consisting of F, Cl, Br, and I, and Z and Q are not the same halogen.

[0013] The inventors have surprisingly discovered that, as shown in the appended examples, the isovalently substituted argentite-germanium sulfide-type solid electrolyte compositions exhibit a high efficiency of up to 2 mS / cm. -1 The increased ionic conductivity.

[0014] Unwilling to be bound by any theory, the inventors believe that heterovalent 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 results in X- / S... 2- Increased site disorder. Therefore, by altering the structure, the lithium content increases, and ion interactions also increase, leading to an increase in ionic conductivity, as illustrated in the appended examples. Furthermore, these observations are supported by computational modeling that focuses on two metrics: E hull (Energy above the convex hull) and E mig (Migration energy barrier) is used to predict the rate of lithium diffusion into the argyrogermanium sulfide structure. Ehull identifies the stability of certain argyrogermanium sulfide compounds, while Emig is a predictor of ionic conductivity.

[0015] In another aspect, the present invention provides a method for manufacturing the solid electrolyte.

[0016] ​In another aspect, the present invention provides a battery comprising a solid electrolyte according to the present invention. Attached Figure Description

[0017] FIG. 1 : , and The X-ray diffraction pattern was recorded at 298 K in a dome-shaped hermetically sealed sample holder from Bruker.

[0018] FIG. 2 X-ray diffraction patterns of and were recorded at 298 K in a dome-shaped hermetically sealed sample holder from Bruker.

[0019] FIG. 3 : and The X-ray diffraction pattern was recorded at 298 K in a dome-shaped hermetically sealed sample holder from Bruker. Detailed Implementation

[0020] Preferred embodiments for carrying out the invention are described in detail in the accompanying drawings and the following detailed description. Although the invention has been described with reference to these specific preferred embodiments, it should be understood that the invention is not limited to these preferred embodiments. Rather, the invention includes numerous alternatives, modifications, and equivalents, as will become apparent from consideration of the following detailed description and drawings.

[0021] As used herein and in the claims, the term “comprising” should not be construed as limited to the manner listed thereafter; it does not exclude other elements or steps. It should be interpreted as specifying the presence of the stated features, integers, steps, or components as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Therefore, the scope of the expression “composition comprising components A and B” should not be limited to compositions consisting solely of components A and B. This means that, for the purposes of this invention, the only relevant components of the composition are A and B. Therefore, the terms “comprising” and “including” encompass the more restrictive terms “consistently composed of” and “composed of”.

[0022] As used herein, the term "solid-state battery" refers to a cell or battery that consists only of solid-state components or basic solid-state components such as solid electrodes (e.g., anodes and cathodes) and a solid electrolyte.

[0023] As used in this article, the term "sulfur-silver-germanium type crystal structure" refers to a crystal structure that resembles naturally occurring crystals. and the crystal structure of a crystal structure of argyrodite or a system. Argyrodite-type crystal structures can be orthorhombic and described in the F-43m space group. In some embodiments, argyrodite-type crystal structures can also be empirically determined, e.g., by X-ray diffraction, by observing diffraction peaks near 2theta = 15.5 ± 1°, 18 ± 1°, 26 ± 1°, 30.5 ± 1°, and 32 ± 1° using Cu Kalpha radiation wavelengths. X-ray diffraction (XRD) as referred to herein refers to XRD experiments performed using a Bruker D8 diffractometer equipped with Cu (Kalpha1 - Kalpha2) radiation in theta-theta configuration. Preferably, a gastight sample holder dome window (transparent to X-rays) from Bruker is used. Preferably, the pattern is collected between 2theta = 10° - 50° in steps of 0.02°.

[0024] Unless otherwise described, ion conductivity as referred to herein refers to ion conductivity determined at 23 °C. Determination is preferably performed on cold-pressed samples in 13 mm dies at 375 MPa using a BioLogic CES H-cell, and spectra are recorded by applying a 50 mV AC perturbation over a frequency range from 7 MHz to 1 Hz using a MTZ 35 frequency response analyzer. Preferably, the relative density of the pellet is 90% to 92%, and the thickness is about 2.5 mm. Preferably, a nickel foil is pressed onto the surface of the pellet as an ion-blocking electrode. More preferably, spectra are collected between temperatures in the range of 23 °C at 10 °C intervals.

[0025] The term "solid electrolyte" as used herein refers to an electrolyte which is essentially free of any liquid. The term "essentially free of liquid" means that the solid electrolyte comprises less than 10 wt.%, relative to the total weight of the solid electrolyte, preferably less than 7.5 wt.%, more preferably less than 5 wt.%, even more preferably less than 2.5 wt.%, most preferably less than 1 wt.% of a liquid. In a more preferred embodiment, the solid electrolyte comprises less than 1000 ppm, preferably less than 500 ppm, more preferably less than 100 ppm, even more preferably less than 50 ppm, most preferably less than 10 ppm of a liquid, based on the total weight of the solid electrolyte.

[0026] Solid electrolyte In a first aspect, the object of the present application is achieved by providing a solid electrolyte having a composition according to formula (I) (I) wherein -1.0 < a < 1.0, Y is selected from the group consisting of Si, Ge, and Ti, and X is selected from the group consisting of F, CI, Br, I, and any combination thereof.

[0027] One highly preferred embodiment is a solid electrolyte according to the present application, with the proviso that when Y = Ge and a = 0, X ≠ Br.

[0028] In certain highly preferred embodiments, the solid electrolyte of the present application is with the proviso that the solid electrolyte does not according to formula (I) (I) wherein X is selected from the group consisting of F, CI, Br, I, and any combination thereof.

[0029] In preferred embodiments, the solid electrolyte is according to the present application, wherein -0.99 < a < 0.99, preferably -0.95 < a < 0.95, more preferably -0.75 < a < 0.75, most preferably -0.5 < a < 0.5.

[0030] In preferred embodiments, the solid electrolyte is according to the present application, wherein a = -0.5, 0 or 0.5, more preferably a = 0.5.

[0031] In certain preferred embodiments, the solid electrolyte is according to the present application, wherein Y is Si, Ge or Ti; preferably Y is Si or Ge, or preferably Y is Si or Ti; more preferably Y is Si.

[0032] In certain preferred embodiments, the solid electrolyte is according to the present application, wherein X is CI, Br, I or a combination thereof; preferably X is Br, I or a combination thereof; more preferably X is Br or I.

[0033] In certain preferred embodiments, the solid electrolyte is according to the present application, wherein X is F, CI, Br or I; preferably X is CI, Br or I; more preferably X is Br or I; most preferably X is I.

[0034] According to a preferred embodiment of the present application, there is provided a solid electrolyte wherein at least 50 mole % of X represents F, preferably at least 80 mole % of X represents F, most preferably X represents F.

[0035] According to a preferred embodiment of the present application, there is provided a solid electrolyte wherein X represents F, CI, Br, I or a combination thereof, and wherein at least 50 mole % of X represents F, preferably at least 80 mole % of X represents F.

[0036] According to a preferred embodiment of the present application, there is provided a solid electrolyte wherein at least 50 mole % of X represents CI, preferably at least 80 mole % of X represents CI, most preferably X represents CI.

[0037] According to a preferred embodiment of the present application, a solid electrolyte is provided, wherein X represents F, CI, Br, I or a combination thereof, and wherein at least 50 mol% of X represents CI, preferably at least 80 mol% of X represents CI.

[0038] According to a preferred embodiment of the present application, a solid electrolyte is provided, wherein at least 50 mol% of X represents Br, preferably at least 80 mol% of X represents Br, most preferably X represents Br.

[0039] According to a preferred embodiment of the present application, a solid electrolyte is provided, wherein X represents F, CI, Br, I or a combination thereof, and wherein 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 application, a solid electrolyte is provided, wherein at least 50 mol% of X represents I, preferably at least 80 mol% of X represents I, most preferably X represents I.

[0041] According to a preferred embodiment of the present application, a solid electrolyte is provided, wherein X represents F, CI, Br, I or a combination thereof, and wherein at least 50 mol% of X represents I, preferably at least 80 mol% of X represents I.

[0042] In certain preferred embodiments, the solid electrolyte is according to the present application, wherein • Y is Si, • X is CI, and • -0.5 < a < 0.5, preferably a = -0.5, 0 or 0.5, more preferably a = -0.5 or 0.5.

[0043] In certain preferred embodiments, the solid electrolyte is according to the present application, wherein • Y is Si, • X is Br, and • -0.5 < a < 0.5, preferably a = -0.5, 0 or 0.5, more preferably a = -0.5 or 0.5.

[0044] In certain preferred embodiments, the solid electrolyte is according to the present application, wherein • Y is Si, • X is I, and • -0.5 < a < 0.5, preferably a = -0.5, 0 or 0.5, more preferably a = 0.5.

[0045] In more preferred embodiments, the solid electrolyte is according to the present application, wherein the solid electrolyte is according to formula (I) a-i:

[0046] In preferred embodiments, the solid electrolyte is a powder.

[0047] In preferred embodiments, the solid electrolyte has a argyrodite crystal structure according to the present application.

[0048] In preferred embodiments, the solid electrolyte according to the present application, wherein the molar ratio of Li:Y:S:X is between (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), 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).

[0049] In preferred embodiments, the solid electrolyte according to the present application has a purity of at least 90%, preferably at least 95%, more preferably at least 99%, as determined by XRD.

[0050] In preferred embodiments, the solid electrolyte according to the present application has an electrical conductivity between 0.1 mS / cm and 5 mS / cm, preferably between 0.5 mS / cm and 3.5 mS / cm, more preferably between 1 mS / cm and 2.5 mS / cm.

[0051] In certain preferred embodiments, the solid electrolyte of the present application according to formula (I) a, preferably has an electrical conductivity between 0.5 mS / cm and 1.5 mS / cm, more preferably between 0.75 mS / cm and 1.25 mS / cm, most preferably about 1.1 mS / cm.

[0052] In certain preferred embodiments, the solid electrolyte of the present application according to formula (I) b, preferably has an electrical conductivity between 0.5 mS / cm and 1.5 mS / cm, more preferably between 0.75 mS / cm and 1.25 mS / cm, most preferably about 1.0 mS / cm.

[0053] In certain preferred embodiments, the solid electrolyte of the present application according to formula (I) d, preferably has an electrical conductivity between 1.0 mS / cm and 2.0 mS / cm, more preferably between 1.25 mS / cm and 1.75 mS / cm, most preferably about 1.5 mS / cm.

[0054] In certain preferred embodiments, the solid electrolyte of the present application according to formula (I)e, preferably has an electrical conductivity of between 1.0 mS / cm and 2.0 mS / cm, more preferably between 1.25 mS / cm and 1.75 mS / cm, most preferably about 1.3 mS / cm.

[0055] In certain preferred embodiments, the solid electrolyte of the present application according to formula (I)f, preferably has an electrical conductivity of between 1.0 mS / cm and 2.0 mS / cm, more preferably between 1.25 mS / cm and 1.75 mS / cm, most preferably about 1.5 mS / cm.

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

[0057] In certain preferred embodiments, the solid electrolyte of the present application according to formula (I)h, preferably has an electrical conductivity of between 1.0 mS / cm and 2.5 mS / cm, more preferably between 1.50 mS / cm and 2.0 mS / cm, most preferably about 1.7 mS / cm.

[0058] In certain preferred embodiments, the solid electrolyte of the present application according to formula (I)i, preferably has an electrical conductivity of between 1.0 mS / cm and 2.5 mS / cm, more preferably between 1.50 mS / cm and 2.0 mS / cm, most preferably about 1.8 mS / cm.

[0059] In certain preferred embodiments, the solid electrolyte according to the present application has a composition according to formula (II) (II) wherein 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, CI, Br and I, Q is selected from the group consisting of F, CI, Br and I, and Z and Q are not the same halogen.

[0060] In preferred embodiments, the solid electrolyte according to formula (II), wherein 0.01 < b < 0.99, preferably 0.25 < b < 0.75, more preferably 0.4 < b < 0.6, most preferably b is about 0.5.

[0061] In preferred embodiments, the solid electrolyte is according to formula (II), wherein Y is Si, Ge or Ti, preferably Y is Si or Ge, or preferably Y is Si or Ti, more preferably Y is Si.

[0062] In preferred embodiments, the solid electrolyte is according to formula (II), wherein Z is Cl, Br or I, preferably Br or I.

[0063] In preferred embodiments, the solid electrolyte is according to formula (II), wherein Q is Cl, Br or I, preferably Br or I.

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

[0065] In certain preferred embodiments, the solid electrolyte is according to formula (II), wherein • Y is Si; • Z is I; • Q is Br; and • 0.25 < b < 0.75, more preferably 0.4 < b < 0.6, most preferably b is about 0.5.

[0066] In more preferred embodiments, the solid electrolyte is according to the present application, wherein the solid electrolyte is according to formula (II) a-b:

[0067] In preferred embodiments, the solid electrolyte is according to formula (II), having a argyrodite-type crystal structure.

[0068] In preferred embodiments, the solid electrolyte is according to formula (II), wherein 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).

[0069] In preferred embodiments, the solid electrolyte has a purity of at least 90%, preferably at least 95%, more preferably at least 99%, according to formula (II), as determined by XRD.

[0070] In preferred embodiments, the solid electrolyte has a conductivity between 0.1 mS / cm and 5 mS / cm, preferably between 0.5 mS / cm and 3.5 mS / cm, more preferably between 1 mS / cm and 2.5 mS / cm, according to formula (II).

[0071] In certain preferred embodiments, the solid electrolyte of the present application according to formula (II) a preferably has a conductivity between 1.5 mS / cm and 2.5 mS / cm, more preferably between 2.0 mS / cm and 2.5 mS / cm, most preferably about 2.4 mS / cm.

[0072] In certain preferred embodiments, the solid electrolyte of the present application according to formula (II) b preferably has a conductivity between 1.5 mS / cm and 2.5 mS / cm, more preferably between 2.0 mS / cm and 2.5 mS / cm, most preferably about 2.1 mS / cm.

[0073] Manufacturing method In a second aspect, the present application provides a method for manufacturing a solid electrolyte, the method comprising the steps of: a) providing a set of precursors comprising Li, S, Y and X; and b) mixing the set of precursors to obtain a solid electrolyte mixture; and c) heat treating the solid electrolyte mixture to obtain a solid electrolyte; wherein Y is selected from the group consisting of Si, Ge and Ti; wherein X is selected from the group consisting of F, Cl, Br and I, preferably Cl, Br or I, more preferably Br or I, most preferably I.

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

[0075] In a highly preferred embodiment, the method is according to the present application, wherein the set of precursors comprises Li2S, one or more of the group consisting of Si2S, Ge2S and Ti2S, preferably Si2S, and one or more of the group consisting of LiI, LiBr and LiCl.

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

[0077] As the skilled person understands, all embodiments relating to the solid electrolyte according to the first aspect of the present application apply mutatis mutandis to the method of manufacturing a solid electrolyte according to the present application. For example, the various embodiments relating to formula (I), formula (II), purity levels and conductivity levels as explained herein in the context of the solid electrolyte equally apply to the method of manufacturing a solid electrolyte according to the present application.

[0078] In a preferred embodiment, the method is according to the present application, wherein the mixing of the solid electrolyte precursors of step b) can comprise mixing, milling, stirring, ball milling or a combination thereof.

[0079] In a preferred embodiment, the method is according to the present application, wherein the mixing of the set of precursors of step b) has a mixing speed of at least 100 rpm, preferably a mixing speed of at least 300 rpm, most preferably a mixing speed of at least 400 rpm. In a preferred embodiment, the method is according to the present application, wherein the mixing of the set of precursors of step b) has a mixing speed of at most 1000 rpm, preferably a mixing speed of at most 900 rpm, most preferably a mixing speed of at most 800 rpm. In a preferred embodiment, the method is according to the present application, wherein the mixing of the set of precursors of step b) has a mixing speed of 100 rpm - 1000 rpm, preferably a mixing speed of 300 rpm - 900 rpm, most preferably a mixing speed of 400 rpm - 800 rpm.

[0080] A certain preferred embodiment is a process according to the present application, wherein the mixing of the set of precursors of step b) is performed by using a mixing device such as a ball mill such as an electric ball mill, a vibratory ball mill, a planetary ball mill, a vibratory mixing mill or a SPEX mill; a bead mill; a homogenizer; a screw mixer; a horizontal mixer; a plowshare mixer; a jar mill; a drum mill or a roller bench. In a more preferred embodiment, the mixing of the set of precursors of step b) is performed by adding one or more ceramic or zirconia balls to the set of precursors. As the skilled person understands, the amount and size of the ceramic or zirconia balls varies depending on the total amount of solids of the set of precursors. As the skilled person understands, these ceramic or zirconia balls are removed prior to the heat treatment step c).

[0081] In a preferred embodiment, the process is according to the present application, wherein the mixing of the set of precursors of step b) is at least 1 hour, preferably at least 5 hours, most preferably at least 10 hours. In a preferred embodiment, the process is according to the present application, wherein the mixing of the set of precursors of step b) is at most 70 hours, preferably at most 50 hours, most preferably at most 30 hours. In a preferred embodiment, the process is according to the present application, wherein the mixing of the set of precursors of step b) is between 1 hour and 70 hours, preferably between 5 hours and 50 hours, most preferably between 10 hours and 30 hours.

[0082] In a preferred embodiment, the process is according to the present application, wherein the mixing of the solid electrolyte precursor mixture of step b) occurs at a temperature of at least 5 °C, preferably at least 10 °C, more preferably at least 15 °C. A preferred embodiment is a process according to the present application, wherein the mixing of the solid electrolyte precursor mixture of step b) occurs at a temperature of less than 50 °C, preferably less than 40 °C, more preferably less than 30 °C. A preferred embodiment is a process according to the present application, wherein the mixing of the solid electrolyte precursor mixture of step b) occurs at a temperature between 5 °C and 50 °C, preferably at a temperature between 10 °C and 40 °C, more preferably at a temperature between 15 °C and 30 °C.

[0083] In certain preferred embodiments, the process is according to the present application, wherein the mixing of the solid electrolyte precursor of step b) • has a mixing time between 1 hour and 70 hours, preferably between 5 hours and 50 hours, most preferably between 10 hours and 30 hours; and • has a mixing speed of 100 rpm - 1000 rpm, preferably a mixing speed of 300 rpm - 900 rpm, most preferably a mixing speed of 400 rpm - 800 rpm.

[0084] In preferred embodiments, the method is according to the present application, wherein the heat treatment of the solid electrolyte mixture of step c) is performed 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, most preferably at least 300 °C. In preferred embodiments, the method is according to the present application, wherein the heat treatment of the solid electrolyte mixture of step c) is performed 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, most preferably less than 500 °C. In preferred embodiments, the method is according to the present application, wherein the heat treatment of the solid electrolyte mixture of step c) is performed at a temperature between 100 °C and 1000 °C, preferably between 200 °C and 750 °C, most preferably between 250 °C and 450 °C.

[0085] In preferred embodiments, the method is according to the present application, wherein the heat treatment of the solid electrolyte mixture of 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, most preferably at least 2 hours. In preferred embodiments, the method is according to the present application, wherein the heat treatment of the solid electrolyte mixture of 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, even more preferably less than 6 hours. In preferred embodiments, the method is according to the present application, wherein the heat treatment of the solid electrolyte mixture of step c) is between 0.5 hours and 24 hours, preferably between 1 hour and 12 hours, more preferably between 2 hours and 6 hours.

[0086] In certain preferred embodiments, the method is according to the present application, wherein the heat treatment of the solid electrolyte mixture of step c) is • at a temperature between 100 °C and 1000 °C, preferably between 200 °C and 750 °C, most preferably between 250 °C and 450 °C; and • between 0.5 hours and 24 hours, preferably between 1 hour and 12 hours, most preferably between 2 hours and 6 hours.

[0087] Method of characterizing a product In a third aspect, the present application relates to a solid electrolyte obtainable by the method according to the second aspect of the present application.

[0088] As the skilled person will appreciate, all embodiments relating to the solid electrolyte according to the first aspect of the application and / or the method according to the second aspect of the application apply mutatis mutandis to the solid electrolyte obtainable by the method according to the application. For example, the various embodiments relating to formula (I), formula (II), purity levels and electrical conductivity levels as explained herein in the context of the solid electrolyte apply equally to the solid electrolyte obtainable by the method for manufacturing the solid electrolyte.

[0089] Battery A fourth aspect of the application relates to 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 comprises a solid electrolyte according to the application. The solid electrolyte of the application 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 for a positive electrode or a negative electrode.

[0090] In a preferred embodiment, the battery is a solid state battery, preferably a lithium solid state battery.

[0091] Use A fifth aspect of the application relates to the use of a solid electrolyte according to the application in a battery, preferably a solid state battery, most preferably a lithium solid state battery.

[0092] A sixth aspect of the application relates to the use of a battery according to the application in any one of a portable computer, a tablet, a mobile phone, an energy storage system, an electric or hybrid electric vehicle.

[0093] The application is further illustrated in the following examples.

[0094] Example Description of test methods Computational scheme The computational model focuses on predicting the thermodynamic stability and the rate of lithium diffusion into the argyrodite structure based on E hull (Energy above convex hull) and E mig migration energy barrier), respectively.

[0095] E hull is a key indicator for identifying the relative stability of a phase compared to other phases present in a multi-component phase diagram of a combination of elements. For example, to identify the phase stability of argyrodite compounds, one would need to calculate The energies of all known phases in chemical space are used to construct a phase diagram. Constructing the convex hull of a multi-component phase diagram at 0 K is a standard computational method. Then, the energy of each phase is calculated relative to the convex hull energy taken as 0 and is termed "E". hull Therefore, E hull The higher the value of , the higher it is above the convex hull of the most stable phase, and therefore the lower its thermodynamic stability. This parameter is used to rank the most stable compounds and indicate the compounds most likely to be synthesized.

[0096] During charging and discharging, lithium ions traverse the potential energy landscape by overcoming energy barriers and transitioning from one stable site to another. The height of these energy barriers is estimated using the bond valence method, which calculates bond lengths (R0) from geometry. A-X ) and its intensity (s A-X The relationship is related to A and X, where A and X are the lithium ion and its neighboring atoms, respectively. The relationship is given by the following equation:

[0097] Where R0 and b These are empirical bond valence (BO) parameters. This relationship allows the location of accessible sites for mobile lithium ions within the local structure of the electrolyte to be defined as the sum of these bond valences, V(A) = ∑x s A-X The closest oxidation state to the ideal valence of lithium ions V ideal The location. The lowest energy path is valence and deviation | V (A)- V ideal(A) | The minimum path, and the corresponding energy barrier is the minimum migration energy barrier for lithium ions to diffuse in the electrolyte. Migration energy barrier (E mig The lower the value of E, the higher the lithium-ion diffusion rate, and therefore the higher the ionic conductivity of the electrolyte. Therefore, E mig This is an ionic conductivity metric used to rank promising candidates. The migration energy has been evaluated using the code BOND_STR, which is distributed within the FullProf package of the CrysFML library.

[0098] Synthetic scheme All synthesis work and sample handling were performed in an Ar-filled glovebox with O2 and H2O levels < 0.1 ppm. Stoichiometric amounts of 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 out to obtain a 15 g batch of precursor. The precursor was transferred to a Restch PM 100 using 250 mL zirconia milling jars with 16 zirconia balls of 20 mm in diameter (ball: powder ratio of 30:1). The precursor was initially milled at 100 rpm for 60 minutes to homogenize the mixture, followed by a total duration of 25 hours of milling at 510 rpm. Each cycle consisted of 5 minutes of milling and 5 minutes of rest, and the milling direction was reversed for each cycle. At the end of the milling step, approximately 96 wt% of material was recovered. The milled powder was placed in a dry quartz tube, which was then sealed under Ar and placed in a furnace (Nabertherm) for heat treatment. The temperature of the furnace was slowly ramped to 300 °C at a rate of 2 °C / min, held for 2 hours, and allowed to cool naturally to room temperature. The post-reaction powder was then crushed using a pestle and mortar and stored in the glovebox for further analysis.

[0099] X-ray diffraction A Bruker D8 diffractometer equipped with a Radiation was used to collect the powder X-ray diffraction patterns in a theta-theta configuration. The measurements were performed using a dome-shaped air-tight sample holder. The patterns were collected between 2theta = 10° - 50° at a step size of 0.02o.

[0100] Ion conductivity measurements Approximately 500 mg of sample were uniaxially cold-pressed in 13 mm dies at 375 MPa. The relative density of the pellets was 90-92% and the thickness was approximately 2.5 mm. These pellets were subjected to AC impedance spectroscopy analysis by mounting them into soft-pack cells and recording the spectra using a Biologic analyzer by applying a 50 mV AC perturbation over a frequency range of 7 MHz to 1 Hz. The spectra were collected at 23 °C. The AC impedance data were analyzed using Zview or RelaxIS software.

[0101] Examples Table 1 shows the E hull and E mig .

[0102]

[0103] Table 1 : E of CEX1-3 and EX1-8 and EX11-20 hull and E mig .

[0104] Table 2 shows the general formula of the examples synthesized via the general synthesis scheme and their respective measured ion conductivities, E hull and E mig .

[0105]

[0106] Table 2: Stoichiometric formula and ion conductivity values of CEX1, CEX4, EX1’-10’ and EX21’. Examples EX1’-8’ and EX11’ are not in accordance with the invention as claimed. Examples EX9’ and EX10’ are in accordance with the invention as claimed.

[0107] n.a. = not applicable.

[0108] The profile matching of the powder X-ray diffraction data indicates that samples EX2, 4, 7 ( FIG. 1 ), EX6 and 7 ( FIG. 2 ) and EX9 and 10 ( FIG. 3 ) retain the argyrodite structure and no peaks corresponding to the precursor or other impurity phases are observed.

Claims

1. A solid electrolyte having a composition according to formula (I) （I） wherein -1.0 < a < 1.0, wherein Y is selected from the group consisting of Si, Ge and Ti, and wherein X is selected from the group consisting of F, Cl, Br, I and any combination thereof, with the proviso that when Y = Ge and a = 0, X ≠ Br and wherein the solid electrolyte has a composition according to formula (II) (I) wherein 0 < b < 1.0, wherein Y is selected from the group consisting of Si, Ge and Ti, wherein Z is selected from the group consisting of F, Cl, Br and I, wherein Q is selected from the group consisting of F, Cl, Br and I, and wherein 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, 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. The solid electrolyte according to any one of claims 1 to 3, wherein 0.01 < b < 0.99, preferably 0.25 < b < 0.75, more preferably 0.4 < b < 0.6, 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. The solid electrolyte according to any one of claims 1 to 7, having a composition according to formula (II) a-b: 。 9. The solid electrolyte according to any one of claims 1 to 8, having an ionic conductivity between 0.1 mS / cm and 5 mS / cm, preferably between 0.5 mS / cm and 2.5 mS / cm, more preferably between 1 mS / cm and 2 mS / cm.

10. A method for manufacturing a solid electrolyte, preferably according to any one of claims 1 to 9, comprising the steps of: a) providing a set of precursors comprising Li, S, Y and X; b) mixing the set of precursors to obtain a solid electrolyte mixture; and c) heat treating the solid electrolyte mixture to obtain a solid electrolyte; wherein Y is selected from the group consisting of Si, Ge and Ti, wherein X is selected from the group consisting of F, Cl, Br and 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, most preferably X is I.

11. The method according to claim 10, wherein X consists of Z and Q, wherein Z is selected from the group consisting of Cl, Br and I, preferably Br or I, more preferably I, 12. The method according to claim 11, wherein Q is selected from the group consisting of Cl, Br and I, preferably Br or I, more preferably I. wherein Q is selected from the group consisting of Cl, Br and I, preferably Br or I, more preferably Br, and 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 comprises the solid electrolyte according to any one of claims 1-9.

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