Method for producing sulfide-based lithium-ion conducting solid electrolytes

Abstract

The present invention relates to a method for producing a solid material obtained by melt quenching a mixture comprising lithium sulfide and boron sulfide, thereby forming a glassy solid suitable for use as a lithium ion conducting electrolyte. The inventors have demonstrated that the method results in the production of sulfide-based lithium ion conducting solid electrolytes of improved quality, in particular sulfide-based lithium ion conducting solid electrolytes with reduced inclusion of foreign bodies such as air bubbles.

Description

[Technical field]

[0001] The present invention relates to a method for producing a solid material obtained by melt quenching a mixture comprising lithium sulfide and boron oxide, thereby forming a glassy solid that is suitable for use as a lithium ion conducting electrolyte. [Background technology]

[0002] The three main functional components of a lithium-ion battery are the anode, the cathode, and the electrolyte. Although many variations exist, the anode of a conventional lithium-ion cell is typically made of carbon, the cathode is typically made of transition metal oxides (particularly oxides of cobalt, nickel, and / or manganese), and the electrolyte is typically a non-aqueous solvent containing a lithium salt. For example, a mixture of an organic carbonate and lithium hexafluorophosphate is a well-known liquid electrolyte for lithium-ion batteries.

[0003] A significant drawback of liquid electrolytes is that their compositions, especially the solvents, are flammable, posing a significant safety risk during normal operation and especially in the event of an accident. Another drawback is inherent to the liquid nature of the electrolyte and is associated with the increased risk of leakage and environmental contamination in the event of a spill or leak.

[0004] In recent years, efforts have been made to develop solid electrolytes that can provide solid-state lithium-ion batteries. Such solid-state batteries have significantly reduced EHS (environmental, health, and safety) hazards. New classes of lithium-ion conducting solid electrolytes include Li2S-SiS2, Li2S-P2S5 or Li2 S-Sulfide-based amorphous solids (interchangeably called glassy solids) such as B2S3. In glassy solid electrolyte materials, the absence of crystalline pathways results in isotropic conduction without virtually any grain boundary resistance. The absence of grain boundaries in glassy electrolyte materials also prevents the formation of dendrites, since glassy amorphous electrolyte materials can be obtained as dense, defect-free films by melt-quenching techniques.

[0005] Early studies on Li2S-B2S3 compositions with molar ratios of 70:30 and 60:40 reported ΔT values ​​of about 70 °C and about 110 °C, respectively. x values ​​were reported (Zhang et al, Solid State Ionics 1990, 38, 217-224).

[0006] US Pat. No. 5,500,291 contemplates sulfide-based lithium ion conducting solid electrolytes of the Li2S-SiS2-Li4SiO4 type.

[0007] WO 2020 / 254314(A1) contemplates sulfide-based lithium ion conducting solid electrolytes of the Li2S-B2S3 type obtained from mixtures further comprising P, Si, Ge, As or Sb oxides in combination with lithium halides.

[0008] WO 2016 / 089899(A1) contemplates a large number of glass systems, many of which are speculative or unsubstantiated.

[0009] A major challenge in the production of glassy solid electrolytes is the avoidance of impurities or inclusions in the glass. Ideally, the glass is a continuous, homogeneous, amorphous bulk. In practice, however, glasses are typically characterized by irregular inclusions of deviant material. This deviant material can be anything, such as unwanted zones of crystallizing material, unreacted precursors, impurities originating from precursors, bubbles, etc. The presence of inclusions is problematic for post-processing of the glass. This type of defect can act as a nucleating agent, favoring the crystallization of the material. The presence of defects induces a material that is no longer isotropic, making the protective behavior against dendrites problematic.

[0010] Therefore, there is currently a great need to provide a method for producing improved quality sulfide-based lithium-ion conducting solid electrolytes with less contamination of stray materials such as unwanted zones of crystallized material, unreacted precursors, impurities from precursors, and air bubbles.

[0011] An object of the present invention is to provide a method for producing a sulfide-based lithium ion conductive solid electrolyte having improved quality, in particular, a method for producing a sulfide-based lithium ion conductive solid electrolyte having little inclusion of foreign matter such as air bubbles.

[0012] Another object of the present invention is to provide a method for producing a sulfide-based lithium-ion conducting solid electrolyte having improved reproducibility compared to prior art methods. Summary of the Invention

[0013] The inventors have found that one or more of the objects of the present invention may be achieved by a method for producing a sulfide-based lithium-ion conducting solid electrolyte, comprising melt-quenching a combination of Li2S; boron; sulfur; B2O3 and optionally LiX, where X represents F, Cl, Br, I, N3, SCN, CN, OCN, BF4, BH4 or a combination thereof, preferably X represents Cl, Br, I or a combination thereof. As shown in the accompanying examples, it is indeed observed that the resulting glassy solid shows less inclusion of deviant materials, in particular less inclusion of gas bubbles, compared to a material prepared using B2S3 instead of both boron and sulfur.

[0014] EMBODIMENT 1 Thus, in a first aspect of the present invention there is provided a method for preparing a solid material comprising the steps of: (i) a precursor of: Li2S; Both boron and sulfur; B2O3; and Optionally providing LiX, where X represents F, Cl, Br, I, N3, SCN, CN, OCN, BF4, BH4 or a combination thereof, preferably X represents Cl, Br, I or a combination thereof; (ii) preparing a mixture comprising the precursor provided in step (i); (iii) heat treating the mixture prepared in step (ii) to obtain a melt; (iv) quenching the melt obtained in step (iii) to obtain a solid material.

[0015] EMBODIMENT 2 In another aspect of the present invention, there is provided a solid material obtainable by the method described herein (i.e., the method of embodiment 1).

[0016] EMBODIMENT 3 In another aspect of the present invention, there is provided a solid composition comprising a first solid material, which is a solid material as described herein (i.e., the solid material of embodiment 2), and further comprising at least a second solid material having a different composition than the first solid material.

[0017] EMBODIMENT 4 In another aspect of the invention, there is provided an electrochemical cell comprising the solid-state material described herein (i.e., the solid-state material of embodiment 2).

[0018] EMBODIMENT 5 In another aspect of the present invention, there is provided the use of a solid material as described herein (i.e. the solid material of embodiment 2) or a solid composition as described herein (i.e. the solid composition of embodiment 3) as a solid electrolyte for an electrochemical cell.

[0019] EMBODIMENT 6 Another aspect of the invention relates to a battery, more particularly a lithium ion battery or a lithium metal battery, comprising at least one electrochemical cell comprising the solid-state material described herein (i.e., the solid-state material of embodiment 2), such as two or more electrochemical cells as described in embodiment 4.

[0020] EMBODIMENT 7 A further aspect of the present invention is a method of making or operating stationary applications such as automobiles, computers, personal digital assistants, mobile phones, watches, camcorders, digital cameras, thermometers, calculators, laptop BIOS, communication devices, remote car locks, and energy storage devices for power generation plants, by using at least one battery or at least one electrochemical cell comprising the solid-state material described herein (i.e., the electrochemical cell described in embodiment 4).

[0021] EMBODIMENT 8 A further aspect of the present disclosure is the use of an electrochemical cell comprising the solid-state material of the present invention (i.e., the electrochemical cell described in embodiment 4) in a motor vehicle, a bicycle operated by an electric motor, a robot, an aircraft (e.g., an unmanned aerial vehicle including a drone), a ship or a stationary energy store. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] In the following detailed description, preferred embodiments are described in detail to realize the practice of the present invention. Although the present invention is described with reference to these specific preferred embodiments, it will be understood that the present invention is not limited to these preferred embodiments. However, to the contrary, the present invention includes numerous alternatives, modifications, and equivalents, as will become apparent from a consideration of the following detailed description of the invention.

[0023] Thermal stability of glass ΔT x can be characterized as the stability against crystallization, which is the onset temperature of crystallization (T x ) and the onset temperature of glass transition (T g ), i.e., ΔT x =T x -T g The larger ΔT x is generally associated with improved glass forming ability and increased glass stability during post-processing.

[0024] The glass transition temperature (T g ) refers to the onset temperature of the glass transition as determined by differential scanning calorimetry (DSC). It is preferably measured by constructing tangents to the baseline of the DSC curve before and after the glass transition and determining the extrapolated onset temperature by the intersection of these tangents, which essentially corresponds to the temperature at which the highest slope in the decline of the DSC baseline occurs before the exothermic crystallization peak. The DSC is preferably recorded using the following temperature profile: from 100°C to 350°C at a rate of 10°C / min, preferably it is recorded on a 5-10 mg sample in a sealed aluminum pan. A suitable DSC instrument is the DSC 3500 Sirius.

[0025] The thermal stability (ΔT x ) is the crystallization onset temperature (T x) and the glass transition temperature (T g ) In other words, ΔT x =T x -T g It is.

[0026] Ionic conductivity referred to herein refers to ionic conductivity measured by electrochemical impedance spectroscopy (EIS) at 25°C. Preferably, it is determined using ion-blocking electrodes on hot-pressed samples densified at 350 MPa and 125°C for 5 minutes, after which the ionic conductivity is measured at 25°C under a working pressure of 125 MPa. Preferably, an excitation voltage of 10 mV was applied in the frequency range of 7 MHz to 1 Hz, and the data was interpreted by equivalent circuit analysis. A suitable conductivity analyzer is a potentiostat with a frequency analyzer, such as those available from Biologic.

[0027] Electronic conductivity referred to herein refers to electronic conductivity determined at 25° C. Preferably, it is determined using ion-blocking electrodes on hot-pressed samples densified at 350 MPa and 125° C. for 5 minutes, after which electronic conductivity is measured at 25° C. under a working pressure of 125 MPa. Preferably, electronic conductivity was measured by step potentiostatic polarization at 0.2 V, 0.4 V and 0.6 V for 20 minutes. A suitable conductivity analyzer is a potentiostat with a frequency analyzer, such as that available from Biologic.

[0028] EMBODIMENT 1 According to a first aspect of the present invention there is provided a method for preparing a solid material comprising the steps of: (i) a precursor of: Li2S; Both boron and sulfur; B2O3; and optionally providing LiX, where X represents F, Cl, Br, I, N3, SCN, CN, OCN, BF4, BH4 or combinations thereof; (ii) preparing a mixture comprising the precursor provided in step (i); (iii) heat treating the mixture prepared in step (ii) to obtain a melt; (iv) quenching the melt obtained in step (iii) to obtain a solid material.

[0029] In a preferred embodiment of the present invention, no other precursors are used in the process. Thus, the solid material obtained in step (iv) is preferably a melt-quenched product of only Li2S; boron; sulfur; B2O3 and optionally LiX, where X represents F, Cl, Br, I, N3, SCN, CN, OCN, BF4, BH4 or a combination thereof.

[0030] In a preferred embodiment of the present invention, the method for preparing a solid material comprises the steps of: (i) a precursor of: Li2S; Both boron and sulfur; B2O3; and Optionally providing LiX, where X represents Cl, Br, I or a combination thereof; (ii) preparing a mixture comprising the precursor provided in step (i); (iii) heat treating the mixture prepared in step (ii) to obtain a melt; (iv) quenching the melt obtained in step (iii) to obtain a solid material.

[0031] In a preferred embodiment of the present invention, no other precursors are used in the process. Thus, the solid material obtained in step (iv) is preferably a melt-quenched product of only Li2S; boron; sulfur; B2O3 and optionally LiX, where X represents Cl, Br, I or a combination thereof.

[0032] The molar ratio of the precursors in the mixture before quenching is preferably such that in step (ii) a composition according to general formula (I) is obtained ((Li2S) x (B2S3) y (B2O3) z) A (LiX) B (I) (In the formula, x is within the range of 55 to 85, preferably 55 to 75, and more preferably 60 to 70; y is within the range of 15 to 45, preferably 20 to 40, and more preferably 25 to 35; z is within the range of 0 to 15, preferably 0 to 10, and more preferably 0 to 6; x+y+z=100; The ratio A:B is in the range of 60:40 to 100:0).

[0033] As will be understood by those skilled in the art in view of the definitions of A and B in formula (I), the ratio A:B relates to the molar ratio of friction products obtained by mixing the precursors Li2S; boron; sulfur; B2O3 with the precursor LiX in molar ratios x, y and z. In practice, it is most convenient when all precursors are simply mixed according to the ratios defined by general formula (I) and then subjected to melt-quenching.

[0034] The provision of both boron and sulfur in step (i) should be interpreted as meaning the provision of elemental boron and elemental sulfur. Elemental boron and elemental sulfur may be provided in amorphous or crystalline form, and the particular allotrope used is not particularly limiting to the present invention. Preferably, the method of the present invention is provided in which the mixture comprising the precursor provided in step (i) does not comprise boron sulfide (B2S3).

[0035] In a preferred embodiment of the present invention, x is within the range of 55 to 85, preferably 55 to 75, and more preferably 60 to 70; y is within the range of 15 to 45, preferably 20 to 40, and more preferably 25 to 35; z is within the range of 1 to 15, preferably 1 to 10, more preferably 1 to 6; A method is provided, where x+y+z=100.

[0036] In a preferred embodiment of the present invention, x is in the range of 62 to 68, preferably in the range of 63 to 67, and more preferably in the range of 64 to 66; y is within the range of 27 to 33, preferably within the range of 28 to 32, and more preferably within the range of 29 to 31; z is in the range of 1 to 8, preferably in the range of 3 to 7, and more preferably in the range of 4 to 6; A method is provided, where x+y+z=100.

[0037] According to a highly preferred embodiment of the present invention, x is about 65; y is about 30; wherein z is about 5.

[0038] Generally, the ratio A:B in the mixture before quenching is preferably within the range of 75:25 to 98:2, preferably 80:20 to 96:4, more preferably 85:15 to 96:4. In some embodiments, the ratio A:B in the mixture before quenching is within the range of 60:40 to 96:4, preferably 70:30 to 96:4, more preferably 75:25 to 96:4. In some embodiments, the ratio A:B in the mixture before quenching is within the range of 60:40 to 94:6, preferably 70:30 to 93:7, more preferably 75:25 to 92:8.

[0039] Thus, in some embodiments of the present invention, x is in the range of 62 to 68, preferably in the range of 63 to 67, and more preferably in the range of 64 to 66; y is within the range of 27 to 33, preferably within the range of 28 to 32, and more preferably within the range of 29 to 31; z is in the range of 1 to 8, preferably in the range of 3 to 7, and more preferably in the range of 4 to 6; x+y+z=100; A process is provided wherein the ratio A:B in the mixture before quenching is in the range of 85:25 to 98:2, preferably in the range of 80:20 to 96:4, more preferably in the range of 85:15 to 96:4.

[0040] In some embodiments of the present invention, x is about 65; y is about 30; z is about 5; x+y+z=100; A process is provided wherein the ratio A:B in the mixture before quenching is in the range of 85:25 to 98:2, preferably in the range of 80:20 to 96:4, more preferably in the range of 85:15 to 96:4.

[0041] According to a preferred embodiment of the present invention, there is provided a method, wherein X represents Br, I or a combination thereof. As shown in the accompanying examples, these materials have a thermal stability ΔT x With respect to X, it outperforms the materials in which X represents Cl.

[0042] According to a preferred embodiment of the present invention, there is provided a method, wherein at least 50 mol % of X represents Br, preferably at least 80 mol % of X represents Br, and most preferably X represents Br. As shown in the accompanying examples, materials in which X represents Br have a thermal stability ΔT x With respect to X, it outperforms the materials in which X represents Cl.

[0043] According to a preferred embodiment of the present invention, there is provided a process, wherein X represents Br, I or a combination thereof, and at least 50 mol % of X represents Br, preferably at least 80 mol % of X represents Br.

[0044] The solid material obtained in step (iv) of the method of the present invention is typically a glassy solid. In some embodiments, the solid material obtained in step (iv) is in the form of a monolithic glass, such as a melt-case monolithic glass. The glassy solid is preferably essentially free of crystalline phases. This may mean, in some embodiments, that the amount of crystalline phase determined by X-ray diffraction is less than 5% by volume, preferably less than 2% by volume, more preferably less than 1% by volume of the solid material. A phase is considered to be crystalline if its reflection intensity is more than 10% higher than the background.

[0045] It has been found that the solid material obtained in step (iv) of the method of the invention has a surprisingly high ionic conductivity. According to a preferred embodiment of the invention, a method is provided, wherein the material obtained in step (iv) has an ionic conductivity of at least 0.1 mS / cm, preferably at least 0.3 mS / cm at 25° C. As shown in the accompanying examples, the inventors have surprisingly found that when at least 50 mol % of X represents Br, preferably at least 80 mol % of X represents Br, and most preferably X represents Br, the ionic conductivity at 25° C. can be as high as 2 mS / cm. Thus, in some embodiments of the invention, a method is provided, wherein the material obtained in step (iv) has an ionic conductivity of at least 1 mS / cm, preferably at least 1.1 mS / cm, more preferably at least 1.2 mS / cm at 25° C. In a particular embodiment of the invention, at least 50 mol % of X represents Br, preferably at least 80 mol % of X represents Br, most preferably X represents Br; The solid material obtained in step (iv) has an ionic conductivity at 25° C. of at least 1 mS / cm, preferably at least 1.1 mS / cm, more preferably at least 1.2 mS / cm.

[0046] For example, in some embodiments of the process of the invention, at least 80 mol % of X represents Br and the ionic conductivity of the solid material obtained in step (iv) is at least 1.1 mS / cm at 25° C., or X represents Br and the ionic conductivity of the solid material obtained in step (iv) is at least 1.2 mS / cm at 25° C., such as at least 1.21 mS / cm or at least 1.25 mS / cm.

[0047] The solid-state materials obtained in step (iv) are found to combine this high ionic conductivity with a surprisingly low electronic conductivity, making them very attractive solid-state battery electrolyte materials. According to a preferred embodiment of the present invention, the materials obtained in step (iv) have a solubility of 1×10 at 25° C. -4 Less than mS / cm, preferably 6×10 -5 As shown in the accompanying examples, the inventors have surprisingly found that when X represents Br, I or a combination thereof, the electronic conductivity at 25° C. is very low, e.g., less than 1×10 -9 Less than mS / cm or 1×10 -10 It has been found that the material obtained in step (iv) may have a viscosity of less than 1×10 mS / cm at 25° C. -5 Less than mS / cm, preferably 1×10 -6 In certain embodiments of the present invention, a method is provided, comprising: X represents Br, I, or a combination thereof; The solid material obtained in step (iv) has a molecular weight of 1×10 -9 Less than mS / cm or 1×10 -10 It has an electronic conductivity of less than mS / cm.

[0048] In some particularly preferred embodiments of the present invention, a process is provided, wherein the material obtained in step (iv) combines high ionic conductivity with low electronic conductivity. As shown in the accompanying examples, this is possible when X represents Br. For example, in some embodiments of the process of the present invention, At least 50 mol% of X represents Br, preferably at least 80 mol% of X represents Br, most preferably X represents Br; the solid material obtained in step (iv) has an ionic conductivity at 25° C. of at least 1 mS / cm, preferably at least 1.1 mS / cm, more preferably at least 1.2 mS / cm; The solid material obtained in step (iv) has a molecular weight of 1×10 -9 Less than mS / cm or 1×10 -10 It has an electronic conductivity of less than mS / cm.

[0049] For example, in some embodiments, at least 50 mol% of X represents Br, preferably at least 80 mol% of X represents Br, and most preferably, X represents Br; the solid material obtained in step (iv) has an ionic conductivity of at least 2 mS / cm at 25° C., and the solid material obtained in step (iv) has an ionic conductivity of at least 1×10 -9 Less than mS / cm or 1×10 -10 It has an electronic conductivity of less than mS / cm.

[0050] As shown in the accompanying examples, the method of the present invention provides high thermal stability ΔT for Li-S based glasses. x It has been found that, according to a preferred embodiment of the present invention, the material obtained in step (iv) has a thermal stability ΔT of more than 100° C., preferably more than 110° C., more preferably more than 115° C. x In some embodiments, particularly when X represents Br, I, or a combination thereof, the thermal stability ΔT x is greater than 120°C, preferably greater than 125°C, more preferably greater than 130°C.

[0051] In one particular highly preferred embodiment, the solid material obtained in step (iv) has an ionic conductivity of at least 0.1 mS / cm, preferably at least 0.3 mS / cm at 25° C.; The solid material obtained in step (iv) has a thermal stability ΔT of more than 100° C., preferably more than 110° C., more preferably more than 115° C. x having; Preferably, the solid material obtained in step (iv) has a molecular weight of 1×10 -5 Less than mS / cm, preferably 1×10 -6 A method is provided in which the electrochemical conductivity is less than mS / cm.

[0052] In one particular highly preferred embodiment, at least 50 mol % of X represents Br, preferably at least 80 mol % of X represents Br, most preferably X represents Br; the solid material obtained in step (iv) has an ionic conductivity at 25° C. of at least 1 mS / cm, preferably at least 1.1 mS / cm, more preferably at least 1.2 mS / cm; The solid material obtained in step (iv) has a thermal stability ΔT of more than 120° C., preferably more than 125° C., more preferably more than 130° C. x having; Preferably, the solid material obtained in step (iv) has a molecular weight of 1×10 -9 Less than mS / cm or 1×10 -10 A method is provided in which the electrochemical conductivity is less than mS / cm.

[0053] For example, in some embodiments, X represents I or Br, preferably Br; the solid material obtained in step (iv) has an ionic conductivity at 25° C. of at least 1.5 mS / cm, more preferably at least 2 mS / cm, and the solid material obtained in step (iv) has a thermal stability ΔT x has.

[0054] In some applications, it may be preferred that the material obtained in step (iv) is provided in the form of a particulate solid, such as a powder. This may facilitate blending, for example, with the cathode material. The solid obtained in step (iv) may be obtained directly in the form of a particulate solid (such as a powder) or may be comminuted (by milling, grinding, etc.) into a particulate solid (such as a powder). In other applications, it may be preferred that the solid material obtained in step (iv) is provided in the form of a thin sheet or film, preferably having a thickness of less than 500 microns, preferably less than 100 microns.

[0055] The preparation of the mixture in step (ii) may be carried out by any suitable means, preferably by mechanical milling (eg ball milling).

[0056] Step (iii) involves heating the mixture prepared in step (ii) to obtain a melt, i.e. a heat treatment at a temperature higher than the melting temperature of the mixture prepared in step (ii). Step (iii) preferably involves heat treating the mixture prepared in step (ii) at a temperature of at least 400° C., preferably at least 600° C., more preferably at least 800° C. The mixture is preferably held at this temperature for at least 15 minutes, preferably at least 30 minutes, more preferably at least 2 hours.

[0057] The heat treatment may be carried out in a sealed vessel. The sealed vessel may be a sealed quartz tube or any other type of vessel that can withstand the temperature of the heat treatment and does not react with the components of the glass, such a sealed vessel being made of a material selected from magnesium oxide, boron nitride, copper, tungsten, silicon nitride, aluminum nitride, carbon, and combinations thereof. The heat treatment of step (iii) may be a single-step heat treatment or a multi-step heat treatment.

[0058] Step (iii) is preferably carried out under an inert gas atmosphere, preferably an inert atmosphere comprising one or more noble gases (such as argon), and / or at a pressure of less than 1 atmosphere, preferably less than 0.1 atmosphere, more preferably less than 0.01 atmosphere. Typically, and thus preferably, step (iii) is carried out at a pressure of less than 10 -4 Less than atmospheric pressure, preferably 10 -5 It is carried out at subatmospheric pressure, preferably under an inert gas atmosphere, preferably an inert atmosphere containing one or more noble gases (such as argon). The use of nitrogen as an inert atmosphere should generally be avoided in view of its potential reaction with the glass precursors.

[0059] In some embodiments of the method of the present invention, step (iv) comprises: (iv) a) quenching the melt obtained in step (iii) to obtain a solid material; (iv)b. grinding the solid material of step (iv)a to obtain a particulate solid, such as a powder; (iv)c Optionally, by dissolving or suspending the particulate solid of step (iv)b in a liquid phase to obtain a solution or suspension followed by deposition from the solution or suspension to obtain a thin film or sheet; or reheating the particulate solid of step (iv)b to a temperature sufficient to permit orientation of the film or sheet, and stretching the film or sheet; forming a thin film or sheet, preferably having a thickness of less than 500 microns, preferably less than 100 microns.

[0060] In another embodiment, step (iv) comprises quenching the melt of step (iii) whilst maintaining a temperature high enough to enable stretching of a thin film or sheet, and stretching said film or sheet, preferably stretching a film or sheet having a thickness of less than 500 microns, preferably less than 100 microns.

[0061] The method is preferably operated as a continuous process to produce a continuous glass film or sheet that is cut to the desired size.

[0062] The quenching step in step (iv) is preferably carried out by direct contact of the melt obtained in step (iii) or by contacting it in a closed or open (preferably closed) container with water, ice, an optionally cooled gas (such as air), an optionally cooled metal plate (such as by roller quenching), and / or a chemically inert mould.

[0063] The solid material obtained in step (iv) is preferably substantially free of gas contaminants, in particular substantially free of gas contaminants at the edges of the material.

[0064] The inventors contemplate adding small amounts of other materials during the synthesis such that the general formula (I) of the resulting solid material is no longer respected, but this change does not substantially affect the basic and novel properties of the solid material of the present invention. Such modifications are considered to be within the scope of the general formula (I) for the purposes of the present invention.

[0065] EMBODIMENT 2 In another aspect of the present invention, there is provided a solid material obtainable by the method described herein (i.e., the method of embodiment 1). Such solid materials are characterized in that they are substantially free of gas inclusions, in particular substantially free of gas inclusions at the edge of the material. As shown in the accompanying examples, the method of the present invention makes it possible to obtain a material without edge bubbles.

[0066] EMBODIMENT 3 In another aspect of the present invention, a solid composition is provided comprising a first solid material, which is a solid material as described herein (i.e., the solid material of embodiment 2), and further comprising at least a second solid material having a composition different from the first solid material. The first solid material may be present in the form of discrete particles embedded in a matrix of the second solid material. Alternatively, the first solid material and the second solid material may be present in the form of discrete particles blended, optionally in combination with a binder material and one or more additional materials, and the blend is preferably compressed. Alternatively, the first solid material and the second solid material may be present in the form of different layers of a multi-layer thin sheet or film, preferably having a total thickness of less than 500 microns, preferably less than 200 microns. Such a solid composition comprising a first solid material, which is a solid material as described herein, and further comprising at least a second solid material having a composition different from the first solid material, is particularly useful as a cathode, anode or separator of an electrochemical cell, particularly as a separator or cathode. In some embodiments, the second solid material is a cathode material, such as a nickel-cobalt or nickel-manganese-cobalt cathode material.

[0067] EMBODIMENT 4 In another aspect of the invention, an electrochemical cell is provided that comprises a solid material as described herein (i.e., the solid material of embodiment 2). In particular, an electrochemical cell is provided in which the cathode, anode and / or separator comprises a solid material as defined herein. In some embodiments, an electrochemical cell is provided in which the cathode, anode and / or separator comprises a solid material as defined herein in the form of a solid composition that comprises a first solid material that is a solid material as described herein and further comprises at least a second solid material having a different composition than the first solid material. Such solid compositions are described in connection with another aspect of the invention. In a particularly preferred embodiment of the invention, an electrochemical cell is provided in which the separator comprises a solid material as defined herein, optionally in the form of a solid composition as described herein. In some embodiments, the separator consists of a solid material as described herein.

[0068] EMBODIMENT 5 In another aspect of the present invention, there is provided the use of the solid material as described herein (i.e. the solid material of embodiment 2) or the solid composition as described herein (i.e. the solid composition of embodiment 3) as a solid electrolyte for an electrochemical cell. Preferably, there is provided the use of the solid material as described herein as a solid electrolyte for an electrochemical cell.

[0069] In the context of the various aspects of the invention described herein, suitable electrochemically active cathode materials and suitable electrochemically active anode materials are known in the art. For example, the anode may include graphitic carbon, metallic lithium, or a metal alloy containing lithium as the anode active material. For example, the cathode may include nickel-cobalt or nickel-manganese-cobalt cathode materials. The electrochemical cells described herein preferably include a Li + The electrochemical cell is a lithium-ion containing cell that is driven by ions. The electrochemical cell may have a disk-like or prismatic shape. The electrochemical cell may include a housing that may be made of steel or aluminum. Multiple electrochemical cells can be combined into an all-solid-state battery that has both solid electrodes and a solid electrolyte.

[0070] EMBODIMENT 6 Another aspect of the present invention relates to a battery, more specifically a lithium ion battery or a lithium metal battery, comprising at least one electrochemical cell comprising the solid-state material described herein (i.e., the solid-state material of embodiment 2), for example, two or more electrochemical cells described in embodiment 4. A particular embodiment relates to a solid-state battery, preferably a lithium solid-state battery, comprising at least one electrochemical cell comprising the solid-state material described herein (i.e., the solid-state material of embodiment 2), for example, two or more electrochemical cells described in embodiment 4. The electrochemical cells described in embodiment 4 can be combined with each other, for example, in a series or parallel connection. A series connection is preferred. Each of the electrochemical cells or batteries described herein can be used to make or operate stationary applications such as automobiles, computers, personal digital assistants, mobile phones, watches, camcorders, digital cameras, thermometers, calculators, laptop BIOS, communication devices, or remote car locks, and energy storage devices for power plants.

[0071] EMBODIMENT 7 A further aspect of the present invention is a method of making or operating stationary applications such as automobiles, computers, personal digital assistants, mobile phones, watches, camcorders, digital cameras, thermometers, calculators, laptop BIOS, communication devices, remote car locks, and energy storage devices for power generation plants, by using at least one battery or at least one electrochemical cell comprising the solid-state material described herein (i.e., the electrochemical cell described in embodiment 4).

[0072] EMBODIMENT 8 A further aspect of the present disclosure is the use of an electrochemical cell comprising the solid material of the present invention (i.e., the electrochemical cell described in embodiment 4) in a motor vehicle, a bicycle operated by an electric motor, a robot, an aircraft (e.g., an unmanned aerial vehicle including a drone), a ship or a stationary energy storage. The present invention further provides a device comprising at least one electrochemical cell described in embodiment 5. Preferred are mobile devices such as vehicles, e.g., automobiles, bicycles, aircraft, or water vehicles, e.g., boats or ships. Other examples of mobile devices are portable ones, e.g., computers, especially laptops, phones, or power tools, e.g., from the construction sector, especially drills, battery-powered screwdrivers or battery-powered tackers.

[0073] The present invention is further illustrated by the following non-limiting examples. EXAMPLES

[0074] 1. Material Preparation In a comparative example, 15 g of final material was produced using the following starting products: amorphous B2S3 (99 wt%), Li2S (99.9 wt%), B2O3 (99.95 wt%) and LiX (LiI (99.9 wt%), LiBr (99 wt%), LiCl (99.9 wt%)). In an argon-filled glove box, appropriate amounts of starting materials were weighed, mixed and introduced into a carbon-coated silica ampoule. The tube was sealed and introduced into a vertical rocking furnace. The melt was homogenized at an internal temperature of 950 °C for 30 min and then quenched in water at room temperature. The ampoule was then opened in an argon-filled glove box. An orange or brown glassy material with good transparency was obtained.

[0075] In the examples, an alternative synthesis was successfully carried out, in which the amount of boron and sulfur provided by B2S3 is provided in the form of amorphous elemental B (99%) and elemental S (99.999%). It was observed that the glass obtained starting from elemental boron and elemental sulfur instead of B2S3 is practically free of edge bubbles and free of visible inclusions, whereas the glass obtained starting from B2S3 has a large amount of visible edge bubbles from the ampoule and carbon inclusions. The presence of inclusions is problematic for the post-processing of the glass. This type of defect can act as a nucleating agent, favoring the crystallization of the material. The presence of defects leads to a material that is no longer isotropic, and therefore the protective behavior against dendrites is problematic.

[0076] 2.Thermal stability ΔT x Decision Thermal analysis was performed using a differential scanning calorimetry DSC 3500 Sirius. 5-10 mg samples of glassy material were placed in sealed aluminum pans and analyzed using the following temperature profile: 100 °C to 350 °C at a rate of 10 °C / min. For all samples, the glass transition temperature (T g ) and the onset of crystallization (T x ) was determined. Thermal stability was then estimated from the simple difference between these values ​​(ΔT x =T x -T g ).

[0077] The glass transition temperature (T) was calculated by constructing tangents to the DSC curve baseline before and after the glass transition and determining the extrapolated onset temperature by the intersection of these tangents. g ) is determined, which essentially corresponds to the temperature at which the highest slope in the drop in the DSC baseline occurs before the exothermic crystallization peak. g The starting temperature is T g It was used as.

[0078] 3. Conductivity Determination Ionic conductivity was measured by electrochemical impedance spectroscopy (EIS) at room temperature (25 °C) for hot-pressed samples in a pellet cell equipped with an ion-blocking electrode. Samples were densified at 350 MPa and 125 °C for 5 min, and ionic conductivity was measured under an operating pressure of 125 MPa. For EIS, an excitation voltage of 10 mV was applied in the frequency range of 7 MHz to 1 Hz. Data were interpreted by equivalent circuit analysis.

[0079] Electronic conductivity was measured at room temperature (25°C) on hot pressed samples in a pellet cell equipped with an ion blocking electrode. Samples were densified at 350 MPa and 125°C for 5 min and electronic conductivity was measured under an operating pressure of 125 MPa. Electronic conductivity was measured by step potentiostatic polarization at 0.2 V, 0.4 V and 0.6 V for 20 min.

[0080] Both measurements were performed using a potentiostat equipped with a frequency analyzer (Biologic).

[0081] 4. Determination of the identity of the obtained glass Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) was applied to the example glassy materials prepared as described above.

[0082] A sample of the glassy material is weighed in a glove box under Ar atmosphere to avoid reactions with water or O2 and added to the microwave vessel. A combination of acids is added, the vessel is closed and digested in the microwave until transparent. The matrix elements (Li&B) are analyzed using high precision ICP-OES techniques.

[0083] S is determined via elemental analysis after sample preparation in an Ar-filled glove box. Sample preparation consists of inserting approximately 100 mg of sample into a sealable capsule, followed by adding the sealed capsule and additives to a ceramic crucible. The filled crucible is then heated in an induction furnace under O2 atmosphere. Any S present is released from the sample and converted to SO2 gas, which is detected by a SO2-specific IR detector. The detected SO2 signal is finally converted to S concentration by using a calibration line and taking into account the exact sample mass.

[0084] The composition of the glasses was found to correspond, within expected limits of experimental error and variation, to the overall formula predicted based on the molar ratios of the precursors subjected to melt-quenching.

[0085] 5.Results [Table 1] [Table 2]

Claims

1. 1. A method for preparing a solid material comprising the steps of: (i) A precursor of: Li ２ S; Both boron and sulfur; B ２ O ３ ;and Optionally, LiX (wherein X is F, Cl, Br, I, N ３ , SCN, CN, OCN, BF ４ , B.H. ４ or a combination thereof; (ii) preparing a mixture comprising the precursor provided in step (i); (iii) heat treating the mixture prepared in step (ii) to obtain a melt; (iv) quenching the melt obtained in step (iii) to obtain the solid material.

2. 2. The method of claim 1 , wherein X represents Cl, Br, I, or a combination thereof.

3. The molar ratio of said precursors in said mixture before quenching is such that in step (ii) a composition according to general formula (I) is obtained ((Li ２ S) ｘ (B ２ S ３ ) ｙ (B ２ O ３ ) ｚ ) Ａ (LiX) Ｂ (I) (In the formula, x is in the range of 55 to 85, preferably 55 to 75, more preferably 60 to 70; y is in the range of 15 to 45, preferably 20 to 40, more preferably 25 to 35; z is in the range of 0 to 15, preferably 0 to 10, more preferably 0 to 6; x+y+z=100; The method of claim 1, wherein the ratio A:B is in the range of 60:40 to 100:

0.

4. The method according to claim 3, wherein z is in the range of 1 to 15, preferably 1 to 10, more preferably 1 to 6.

5. x is in the range of 62 to 68, preferably 63 to 67, more preferably 64 to 66; y is in the range of 27 to 33, preferably 28 to 32, more preferably 29 to 31; z is in the range of 1 to 8, preferably 3 to 7, more preferably 4 to 6; 4. The method of claim 3, wherein x+y+z=100.

6. x is about 65; y is about 30; The method of claim 5 , wherein z is about 5.

7. The method of claim 1 , wherein the solid material is a glassy solid.

8. 2. The method of claim 1, wherein the solid material has an ionic conductivity of at least 0.1 mS / cm, preferably at least 1 mS / cm, at 25°C.

9. The solid material has a thermal stability ΔT of greater than 100° C., preferably greater than 110° C., more preferably greater than 115° C. ｘ and ΔT ｘ = T ｘ -T ｇ (In the formula, T ｘ is the crystallization onset temperature determined by DSC, T ｇ is the glass transition temperature determined by DSC).

10. 2. The method of claim 1, wherein step (iii) comprises heat treating the mixture prepared in step (ii) to a temperature of at least 400°C, preferably at least 600°C, more preferably at least 800°C.

11. The method of claim 1 , wherein step (ii) comprises mechanical milling.

12. 2. The method of claim 1, wherein step (iii) is carried out in a sealed vessel, preferably made from a material selected from magnesium oxide, pyrolytic boron nitride, copper, tungsten, silicon nitride, aluminum nitride, and combinations thereof.

13. Step (iv) is (iv) a) quenching the melt obtained in step (iii) to obtain a solid material; (iv)b. grinding the solid material of step (iv)a to obtain a particulate solid, such as a powder; (iv) c optionally, by dissolving or suspending said particulate solid of step (iv)b in a liquid phase to obtain a solution or suspension and subsequently depositing from said solution or suspension to obtain a thin film or sheet; or reheating the particulate solid of step (iv)b to a temperature sufficient to permit orientation of the film or sheet, and stretching the film or sheet; The method of claim 1 further comprising forming a thin film or sheet, preferably having a thickness of less than 500 microns, preferably less than 100 microns.

14. 13. A solid material obtainable by the method of claim 1, said solid material being substantially free of gas entrainment.

15. 15. An electrochemical cell comprising the solid-state material of claim 14.

16. 16. The electrochemical cell of claim 15 comprising a cathode, an anode, and a separator, the separator comprising the solid-state material of claim 14.

17. 15. Use of the solid material according to claim 14 as a solid electrolyte for an electrochemical cell.

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