Inorganic compounds having a structure of argyrodite type, processes for the preparation thereof, and uses thereof in electrochemical applications

Abstract

The invention relates to inorganic compounds having a structure of argyrodite type which are derived from a process comprising a step of grinding alkali metal sulfide, alkali metal sulfate, phosphorus pentasulfide and an alkali metal halide. Also described are electrode materials, electrodes, electrolytes comprising said compounds, and the uses thereof in electrochemical cells, in particular in batteries known as all-solid-state batteries. Prolonged grinding of the precursors, followed by little or no annealing, gives compounds of formula M6-xPS5-x-yOyZ1i+x or M6-x2yPS5-x-yOyZi+x in which M is chosen from Li, Na and K, Z is a halogen atom chosen from F, Cl, Br and I, where x denotes the number of Z in excess of 1 or is equal to zero, and y is a number other than zero.

Description

[0001] INORGANIC COMPOUNDS HAVING AN ARGYRODITE-TYPE STRUCTURE, METHODS OF PREPARATION THEREOF AND THEIR USES IN ELECTROCHEMICAL APPLICATIONS

[0002] RELATED REQUESTS

[0003] This application claims priority under applicable law from Canadian Provisional Patent Application No. 3,136,069 filed on October 27, 2021 and from the Canadian Provisional Patent Application entitled “INORGANIC COMPOUNDS HAVING AN ARGYRODITE-LIKE STRUCTURE, PROCESSES FOR THEIR PREPARATION AND THEIR USES IN ELECTROCHEMICAL APPLICATIONS” filed on October 12, 2022, the contents of which are incorporated herein by reference in their entirety and for all purposes.

[0004] TECHNICAL FIELD

[0005] The present application relates to the field of inorganic oxysulfide compounds having an argyrodite-type structure and to their uses in electrochemical applications. More particularly, the present application relates to the field of inorganic oxysulfide compounds having an argyrodite-type structure, to electrode materials and solid electrolytes comprising them, to their production processes and to their uses in electrochemical cells, in particular in so-called all-solid-state batteries.

[0006] STATE OF THE ART

[0007] Inorganic compounds such as sulfide-based ceramics, glasses, and glass-ceramics are promising materials for many technological applications since they enable the development of all-solid-state electrochemical systems that are substantially safer.

[0008] In addition, inorganic sulfide compounds exhibit a wide window of electrochemical stability and substantially higher ionic conductivity at room temperature. Indeed, inorganic solid electrolytes comprising them exhibit ionic conductivities at room temperature comparable to those of liquid organic electrolytes, and therefore, substantially higher than those of their counterparts based on the use of solid polymer electrolytes. For example, argyrodite of formula LiePSsX (in which, X is Cl, Br or I) exhibits an ionic conductivity at room temperature in the order of mS.cnr 1 .

[0009] However, the use of argyrodite-type inorganic compounds is limited by their high production cost, particularly due to the use of lithium sulfide (U2S) as a precursor and sulfur source and a high-temperature annealing step allowing the production of interesting ionic conductivities. One of the key elements of the industrial requirements related to the production of this type of inorganic compounds is therefore to minimize costs by lowering the U2S utilization rate and the annealing temperature while maintaining a considerably high ionic conductivity.

[0010] In addition, argyrodite-type inorganic compounds are associated with problems related to their interfacial stability as well as their stability to ambient air and humidity. Specifically, these inorganic solid electrolytes generate hydrogen sulfide (H2S) gas upon contact with humid air and must therefore be prepared, assembled, and operated under an inert atmosphere. One strategy employed to address this problem involves the use of oxysulfide-based inorganic argyrodite compounds. Indeed, partial atomic substitution of sulfur and / or lithium in these inorganic compounds by oxygen would result in a significant decrease in H2S generation in the presence of humidity.

[0011] Therefore, there remains a need for the development of inorganic compounds for use in all-solid-state electrochemical systems excluding one or more of the above-mentioned disadvantages.

[0012] SUMMARY

[0013] In some aspects, embodiments of the technology as described herein include the following:

[0014] 1. A method for preparing an inorganic compound having an argyrodite-type structure based on an alkali metal, the method comprising a step of grinding alkali metal sulfide, alkali metal sulfate, phosphorus pentasulfide and an alkali metal halide, wherein the alkali metal is selected from lithium, sodium and potassium, for example, the alkali metal is lithium. 2. The method of item 1, wherein the alkali metal halide is selected from alkali metal fluoride, alkali metal chloride, alkali metal bromide, alkali metal iodide and a mixture of at least two thereof.

[0015] 3. Process according to item 2, in which the alkali metal halide is the alkali metal chloride.

[0016] Process according to item 2, in which the alkali metal halide is the alkali metal bromide.

[0017] 5. Process according to item 2, in which the alkali metal halide is the alkali metal iodide.

[0018] 6. Process according to item 2, in which the alkali metal halide is a mixture of alkali metal chloride and alkali metal bromide.

[0019] 7. A method according to item 2, wherein the alkali metal halide is a mixture of alkali metal chloride, alkali metal bromide and alkali metal iodide.

[0020] 8. A method according to any one of items 1 to 7, wherein the argyrodite-type structure is of formula in which M is the chosen alkali metal from Li, Na and K, for example M is Li, Z is a halogen atom selected from F, Cl, Br and I, x denotes the number of Z in excess of 1 or is equal to zero, and y is a number other than zero (for example, 0 ≤ x ≤ 1 and 0 < y ≤ 1).

[0021] 9. Method according to item 8, in which x is a number other than zero (for example, 0 < x ≤ 1).

[0022] 10. Method according to item 8 or 9, in which x and y are selected to achieve electroneutrality.

[0023] 11. Method according to any one of items 8 to 10, in which the argyrodite-type structure is chosen from inorganic compounds having an argyrodite-type structure of formulas in which M is as defined in item 8.

[0024] 12. Method according to any one of items 8 to 10, in which the argyrodite-type structure is chosen from inorganic compounds having an argyrodite-type structure of formulas

[0025] 13. A method according to any one of items 1 to 7, wherein the argyrodite-type structure is of formula , in which M is the alkali metal selected from Li, Na and K, for example M is Li, Z is a halogen atom selected from F, Cl, Br and I, x denotes the number of Z in excess of 1 or is equal to zero, and y is a number other than zero (for example, 0 ≤ x ≤ 1 and 0 < y ≤ 1).

[0026] 14. Method according to item 13, in which x is a number other than zero (for example, 0 < x ≤ 1).

[0027] 15. Method according to item 13 or 14, in which the argyrodite-type structure is chosen from inorganic compounds having an argyrodite-type structure of formulas in which M is as defined in item 13.

[0028] 16. Method according to item 15, in which the argyrodite-type structure is chosen from inorganic compounds having an argyrodite-type structure of formulas

[0029] 17. A method according to any one of items 1 to 16, wherein the grinding step is carried out using a grinder.

[0030] 18. Method according to item 17, in which the mill is a planetary mill.

[0031] 19. A method according to any one of items 1 to 18, wherein the grinding step is carried out at a rotational speed in the range from about 300 rpm to about 800 rpm. 20. A method according to any one of items 1 to 18, wherein the grinding step is carried out at a rotational speed in the range from about 400 rpm to about 700 rpm.

[0032] 21. A method according to any one of items 1 to 18, wherein the grinding step is carried out at a rotational speed in the range from about 500 rpm to about 700 rpm.

[0033] 22. A method according to any one of items 1 to 18, wherein the grinding step is carried out at a rotational speed of approximately 600 rpm.

[0034] 23. A method according to any one of items 1 to 22, wherein the grinding step is carried out for a period of time in the range from about 5 hours to about 20 hours.

[0035] 24. A method according to any one of items 1 to 22, wherein the grinding step is carried out for approximately 10 hours.

[0036] 25. A method according to any one of items 1 to 24, wherein the grinding step is carried out in a grinding ball:precursor ratio in the range of about 10 to about 30.

[0037] 26. A method according to any one of items 1 to 24, wherein the grinding step is carried out in a grinding balls:precursors ratio of approximately 30.

[0038] 27. Method according to any one of items 1 to 26, which further comprises an annealing step carried out at a maximum temperature of approximately 400°C.

[0039] 28. A method according to any one of items 1 to 26, which further comprises an annealing step carried out at a maximum temperature of approximately 300°C.

[0040] 29. A method according to any one of items 1 to 26, which is free from an annealing step.

[0041] 30. An inorganic compound having an argyrodite-type structure obtained according to the process as defined in any one of items 1 to 29. 31. An electrode material comprising an electrochemically active material and an inorganic compound having an argyrodite-type structure as defined in item 30 or obtained according to the process as defined in any one of items 1 to 29.

[0042] 32. Electrode material according to item 31, in which the inorganic compound having an argyrodite-type structure is present as an additive.

[0043] 33. Electrode material according to item 31 or 32, wherein the inorganic compound having an argyrodite-type structure is present as a coating material.

[0044] 34. Electrode material according to item 33, wherein the coating material forms a coating layer on the surface of the electrochemically active material.

[0045] 35. An electrode material according to any one of items 31 to 34, wherein the electrochemically active material is selected from a metal oxide, a metal sulfide, a metal oxysulfide, a metal phosphate, a metal fluorophosphate, a metal oxyfluorophosphate, a metal sulfate, a metal halide, a metal fluoride, sulfur, selenium, and a combination of at least two thereof.

[0046] 36. Electrode material according to item 35, wherein the metal of the electrochemically active material is selected from titanium (Tl), iron (Fe), manganese (Mn), vanadium (V), nickel (Ni), cobalt (Co), aluminum (Al), chromium (Cr), copper (Cu), zirconium (Zr), niobium (Nb), molybdenum (Mo), tungsten (W) and a combination of at least two of these.

[0047] 37. Electrode material according to item 35 or 36, wherein the metal of the electrochemically active material further comprises an alkali or alkaline earth metal selected from lithium (Li), sodium (Na), potassium (K) and magnesium (Mg).

[0048] 38. An electrode material according to any one of items 31 to 37, wherein the electrochemically active material is a lithium metal oxide.

[0049] 39. Electrode material according to item 38, wherein the lithium metal oxide is a mixed oxide of lithium, nickel, manganese and cobalt (NCM). 40. Electrode material according to any one of items 31 to 34, wherein the electrochemically active material is selected from a non-alkali or non-alkaline earth metal, an intermetallic compound, a metal oxide, a metal nitride, a metal phosphide, a metal phosphate, a metal halide, a metal fluoride, a metal sulfide, a metal oxysulfide, a carbon, silicon (Si), a silicon-carbon (Si-C) composite, a silicon oxide (SIO X ), a silicon oxide-carbon composite (SIOx-C), tin (Sn), a tin-carbon composite (Sn-C), a tin oxide (SnO x ), a tin oxide-carbon composite (SnOx-C), and a combination of at least two of these.

[0050] 41. An electrode material according to any one of items 31 to 40, wherein the electrochemically active material further comprises a doping element.

[0051] 42. An electrode material according to any one of items 31 to 41, wherein the electrochemically active material further comprises a coating material.

[0052] 43. Electrode material according to item 42, wherein the coating material is an electronically conductive material.

[0053] 44. Electrode material according to item 43, wherein the electronically conductive material is carbon.

[0054] 45. Electrode material according to item 42, wherein the coating material is chosen from , other similar coating materials and a combination of at least two of these.

[0055] 46. ​​Electrode material according to item 45, wherein the coating material is LiNbO3.

[0056] 47. Electrode material according to any one of items 31 to 46, which further comprises at least one electronically conductive material.

[0057] 48. The electrode material of item 47, wherein the electronically conductive material is selected from the group consisting of carbon black, acetylene black, graphite, graphene, carbon fibers, carbon nanofibers, carbon nanotubes, and a mixture of at least two thereof. 49. The electrode material of item 48, wherein the electronically conductive material is a mixture of carbon black and gas-formed carbon fibers (VGCFs).

[0058] 50. Electrode material according to any one of items 31 to 49, which further comprises at least one additive.

[0059] 51. Electrode material according to item 50, wherein the additive is selected from inorganic ionic conductive materials, inorganic materials, glasses, glass-ceramics, ceramics, nano-ceramics, salts and a combination of at least two of these.

[0060] 52. Electrode material according to any one of items 31 to 51, which further comprises a binder.

[0061] 53. Electrode material according to item 52, wherein the binder is selected from the group consisting of a polyether, polycarbonate or polyester type polymer binder, a fluoropolymer and a water-soluble binder.

[0062] 54. An electrode comprising the electrode material as defined in any one of items 31 to 53 on a current collector.

[0063] 55. A self-supporting electrode comprising the electrode material as defined in any of items 31 to 53.

[0064] 56. An electrolyte comprising an inorganic compound having an argyrodite-type structure as defined in item 30 or obtained according to the process as defined in any one of items 1 to 29.

[0065] 57. Electrolyte according to item 56, said electrolyte being a liquid electrolyte comprising a salt in a solvent.

[0066] 58. Electrolyte according to item 56, said electrolyte being a gel electrolyte comprising a salt in a solvent and optionally a solvating polymer.

[0067] 59. Electrolyte according to item 56, said electrolyte being a solid polymer electrolyte comprising a salt in a solvating polymer. 60. Electrolyte according to any one of items 56 to 59, in which the inorganic compound having an argyrodite-type structure is present as an additive.

[0068] 61. Electrolyte according to item 56, said electrolyte being an inorganic solid electrolyte.

[0069] 62. Electrolyte according to item 56, said electrolyte being a polymer-ceramic hybrid solid electrolyte.

[0070] 63. Electrolyte according to item 61 or 62, wherein the inorganic compound having an argyrodite-type structure is present as the inorganic solid electrolyte material.

[0071] 64. Electrolyte according to any one of items 56 to 63, which further comprises at least one additional component.

[0072] 65. Electrolyte according to item 64, wherein the additional component is selected from ionic conductive materials, inorganic particles, glass or ceramic particles and a combination of at least two of these.

[0073] 66. An electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein at least one of the positive electrode or the negative electrode is as defined in item 54 or 55 or comprises an electrode material as defined in any of items 31 to 53.

[0074] 67. An electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein the electrolyte is as defined in any one of items 56 to 65.

[0075] 68. An electrochemical cell according to item 66 or 67, wherein the negative electrode comprises an electrochemically active material comprising an alkali metal, an alkaline earth metal, an alloy comprising at least one alkali or alkaline earth metal, a non-alkaline and non-alkaline earth metal, or an alloy or an intermetallic compound. 69. An electrochemical cell according to item 68, wherein the electrochemically active material of the negative electrode comprises metallic lithium or an alloy including or based on metallic lithium.

[0076] 70. An electrochemical cell according to any one of items 66 to 68, wherein the positive electrode is pre-lithiated and the negative electrode is substantially free of lithium.

[0077] 71. Electrochemical cell according to item 70, in which the negative electrode is lithiated in situ during the cycling of said electrochemical cell.

[0078] 72. An electrochemical accumulator comprising at least one electrochemical cell as defined in any one of items 66 to 71.

[0079] 73. Electrochemical accumulator according to item 72, wherein said electrochemical accumulator is a battery selected from a lithium battery, a lithium-ion battery, a sodium battery, a sodium-ion battery, a magnesium battery, and a magnesium-ion battery.

[0080] 74. Electrochemical accumulator according to item 73, wherein said battery is a lithium battery or a lithium-ion battery.

[0081] 75. Electrochemical accumulator according to any one of items 72 to 74, in which said electrochemical accumulator is a so-called all-solid-state battery.

[0082] BRIEF DESCRIPTION OF THE FIGURES

[0083] Figure 1 shows X-ray diffraction patterns obtained for the powders of Argyrodites 1 to 4 and 8, as described in Example 2.

[0084] Figure 2 shows X-ray diffraction patterns obtained for the powders of Argyrodites 2 and 5 to 7, as described in Example 2.

[0085] Figure 3 shows X-ray diffraction patterns obtained for the powders of Argyrodites 2, 3, 9 and 10, as described in Example 2.

[0086] Figure 4 shows X-ray diffraction patterns obtained for the powders of Argyrodites 2 and 12 to 15, as described in Example 2. Figure 5 shows X-ray diffraction patterns obtained for the powders of Argyrodites 16 to 19, as described in Example 2.

[0087] Figure 6 shows X-ray diffraction patterns obtained for the powders of Argyrodites 2, 13, 20 and 21, as described in Example 2.

[0088] Figure 7 shows nuclear magnetic resonance spectra of lithium ( 6 Li NMR) obtained for Argyrodites 2 and 9, as described in Example 3.

[0089] Figure 8 shows nuclear magnetic resonance spectra of phosphorus ( 31 P NMR) obtained for Argyrodites 2 and 9, as described in (Example 3.

[0090] Figure 9 shows a nuclear magnetic resonance spectrum of lithium ( 6 Li NMR) obtained for Argyrodite 7, as described in Example 3.

[0091] Figure 10 shows a nuclear magnetic resonance spectrum of phosphorus ( 31 P NMR) obtained for Argyrodite 7, as described in Example 3.

[0092] Figure 11 shows nuclear magnetic resonance spectra of lithium ( 6 Li NMR) obtained for Argyrodites 13 and 16, as described in Example 3.

[0093] Figure 12 shows nuclear magnetic resonance spectra of phosphorus ( 31 P NMR) obtained for Argyrodites 13 and 16, as described in Example 3.

[0094] Figure 13 shows a plot of H2S gas volume normalized by argyrodite mass generated as a function of time for Argyrodites 2, 7, 8, 11, 13, and 16, as described in Example 4.

[0095] Figure 14 is a graph showing the ionic conductivity results versus temperature for the Cells, as described in Example 5(b).

[0096] Figure 15 is a graph showing the ionic conductivity results versus temperature for the Cells, as described in Example 5(b). Figure 16 is a graph showing the ionic conductivity results versus temperature for the Cells, as described in Example 5(b).

[0097] Figure 17 is a graph showing the ionic conductivity results versus temperature for the Cells, as described in Example 5(b).

[0098] Figure 18 is a graph showing the ionic conductivity results versus temperature for the Cells, as described in Example 5(b).

[0099] Figure 19 is a graph showing the ionic conductivity results versus temperature for the Cells, as described in Example 5(b).

[0100] Figure 20 shows cyclic voltammograms obtained for Cells 22 and 23 recorded at a scan rate of 0.05 mV / s between 2.5 V and 4.2 V vs Li / Li* at a temperature of about 30 °C, as described in Example 6(b).

[0101] Figure 21 shows a graph of charge (•) and discharge capacity and the coulombic efficiency (A) as a function of the number of cycles per 100 cycles obtained for Cell 24, as described in Example 7(c).

[0102] Figure 22 shows the discharge profiles obtained for Cell 24 as a function of capacity obtained at charge and discharge currents of C / 10, C / 4 and C / 2 and recorded vs Li / Li* at a temperature of 30°C, as described in Example 7(c).

[0103] Figure 23 shows the discharge profiles obtained for Cell 24 as a function of time obtained at charge and discharge currents of C / 10, C / 4 and C / 2 and recorded vs Li / Li* at a temperature of 30°C, as described in Example 7(c).

[0104] DETAILED DESCRIPTION

[0105] The following detailed description and examples are presented for illustrative purposes only and should not be construed as further limiting the scope of the invention. Rather, they are intended to cover all alternatives, modifications, and equivalents that may be included as defined by this description. The objects, advantages, and other features of the present inorganic compounds having an argyrodite-type structure, their preparation processes, and electrode materials, electrodes, electrolytes, electrochemical cells, and electrochemical accumulators comprising them will be more apparent and better understood upon reading the following non-restrictive description and references to the accompanying figures.

[0106] All technical and scientific terms and expressions used herein have the same definitions as those generally understood by those skilled in the art of the present technology. Definitions of certain terms and expressions used are nevertheless provided below.

[0107] When the term "about" is used here, it means approximately, in the region of, or around. For example, when the term "about" is used in connection with a numerical value, it modifies it above and below by a variation of 10% from its nominal value. This term may also take into account, for example, the experimental error of a measuring device or rounding.

[0108] Where a range of values ​​is referred to in this application, the lower and upper bounds of the range are, unless otherwise indicated, always included in the definition. Where a range of values ​​is referred to in this application, then all intermediate ranges and sub-ranges, as well as individual values ​​included in ranges of values, are included in the definition.

[0109] When the article "a" is used to introduce an element in the present application, it does not have the meaning of "a single one", but rather of "one or more". Of course, where the description states that a particular step, component, element or feature "may" or "could" be included, that particular step, component, element or feature is not required to be included in every embodiment.

[0110] The term "self-supporting electrode" as used herein refers to an electrode without a metallic current collector.

[0111] The present technology relates to a method for preparing an inorganic compound having an argyrodite-type structure based on M2S-P2S5-M2SO4-MZ (wherein, M is an alkali metal selected from lithium (Li), sodium (Na), potassium (K), and a combination of at least two thereof, and Z is a halogen atom selected from fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), or a combination of at least two thereof), the method comprising a step of directly grinding precursors. In some examples, M is lithium. The precursors consist of alkali metal sulfide (M2S), alkali metal sulfate (M2SO4), phosphorus pentasulfide (P2S5) and an alkali metal halide, selected from alkali metal fluoride, alkali metal chloride, alkali metal bromide, alkali metal iodide and a mixture of at least two of these.

[0112] According to one example, inorganic compounds having an argyrodite-type structure may be respectively of formulas in in which Z and M are as defined, x denotes the number of Z in excess of 1 or is equal to zero, and y is a number other than zero, for example 0 ≤ x ≤ 1 and 0 < y ≤ 1. According to one example, x is a number other than zero (for example, 0 < x ≤ 1). Inorganic compounds having an argyrodite-type structure can therefore be obtained by grinding from the precursors as defined respectively according to the following reaction equations: in which, x, y, M and Z are such quid defined.

[0113] In one example, when the inorganic compound has an argyrodite-like structure, x is the number of Zs in excess of 1 or is zero, y is a nonzero number, and x and y are selected to achieve a desired stoichiometry or to achieve electroneutrality. Non-limiting examples of inorganic compounds having an argyrodite-like structure according to Equation 1 include inorganic compounds having an argyrodite-like structure of formulas in which M and Z are as defined. When the inorganic compound has an argyrodite-like structure including less than the alkali metal (i.e., an inorganic compound having an argyrodite-like structure according to Equation 2), x is the number of Zs in excess of 1 or is zero, y is a nonzero number, and x and y are selected to achieve a desired stoichiometry. Non-limiting examples of inorganic compounds having an argyrodite-like structure according to Equation 2 include inorganic compounds having an argyrodite-like structure of formulae in which M and Z are as defined herein.

[0114] In an example of interest, Z is a chlorine atom and the alkali metal halide is the alkali metal chloride. For example, the inorganic compound having an argyrodite-type structure may be selected from inorganic compounds having an argyrodite-type structure of formulae in which M is as defined here.

[0115] In another example of interest, Z is a bromine atom and the alkali metal halide is the alkali metal bromide. For example, the inorganic compound having an argyrodite-type structure may be selected from inorganic compounds having an argyrodite-type structure of formulae in which M is as defined herein. For example, the compound inorganic having an argyrodite-type structure may be an inorganic compound having an argyrodite-type structure of formula in which M is as defined here.

[0116] In another example of interest, Z is an iodine atom and the alkali metal halide is the alkali metal iodide. For example, the inorganic compound having an argyrodite-type structure may be selected from inorganic compounds having an argyrodite-type structure of formulae , in which M is as defined herein.

[0117] In an example of interest, Z is a combination including chlorine and bromine and the alkali metal halides are a mixture of alkali metal chloride and alkali metal bromide. For example, the inorganic compound having an argyrodite-type structure may be selected from inorganic compounds having an argyrodite-type structure of formulae in which M is as defined here. In an example of interest, Z is a combination including chlorine, bromine and iodine and the alkali metal halides are a mixture of alkali metal chloride, alkali metal bromide and alkali metal iodide. For example, the inorganic compound having an argyrodite-type structure may be selected from inorganic compounds having an argyrodite-type structure of formulae in which M is as defined here.

[0118] In an example of interest, the alkali metal is lithium and the inorganic compound having an argyrodite-type structure is based on (in which, Z is a halogen atom selected from F, Cl, Br and I, or a combination of at least two of these), the method comprising a step of direct grinding of the precursors. The precursors being constituted by lithium sulfide (Li2S), lithium sulfate (Li2SO4), phosphorus pentasulfide (P2S5) and a lithium halide, selected from lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI) and a mixture of at least two of these.

[0119] Non-limiting examples of inorganic compounds having an argyrodite-like structure according to Equation 1 include inorganic compounds having an argyrodite-like structure of formulas in which Z is as defined herein. Examples non-limiting examples of inorganic compounds having an argyrodite-type structure according to Equation 2 include inorganic compounds having an argyrodite-type structure of formulae , in which Z is as defined herein.

[0120] In an example of interest, Z is a chlorine atom and the lithium halide is LiCl. For example, the inorganic compound having an argyrodite-type structure may be selected from inorganic compounds having an argyrodite-type structure of formulae

[0121] In another example of interest, Z is a bromine atom and the lithium halide is LiBr. For example, the inorganic compound having an argyrodite-type structure may be selected from inorganic compounds having an argyrodite-type structure of formulae For example, the inorganic compound having an argyrodite-like structure may be an inorganic compound having an argyrodite-like structure of formula

[0122] According to another example of interest, Z is an iodine atom and the lithium halide is Lil. For example, the inorganic compound having an argyrodite-type structure can be chosen from inorganic compounds having an argyrodite-type structure of formulas

[0123] According to an example of interest, Z is a combination including chlorine and bromine and the lithium halides are a mixture of LICI and LiBr. For example, the inorganic compound having an argyrodite-type structure may be selected from inorganic compounds having an argyrodite-type structure of formulas

[0124] According to an example of interest, Z is a combination including chlorine, bromine and iodine and the lithium halides are a mixture of LiCl, LiBr and LiI. For example, the inorganic compound having an argyrodite-type structure may be selected from inorganic compounds having an argyrodite-type structure of formulas

[0125] According to another example of interest, the method as defined herein is carried out in one step. That is to say, preferably, the method does not include an annealing step. Alternatively, the method may include an optional low-temperature annealing step. For example, if the method includes an annealing step, this may be carried out at a maximum temperature of about 400°C or at a maximum temperature of about 300°C.

[0126] In another example, the grinding step may be performed using a mill, for example, a planetary mill. Any known compatible mill type is contemplated. For example, the grinding step may be performed at a rotational speed, for a determined time, and in a ratio of grinding balls to precursors that provides an inorganic compound having the desired argyrodite-type structure. In another example, the grinding step may be performed at a rotational speed in the range of about 300 rpm to about 800 rpm, or from about 400 rpm to about 700 rpm, or from about 500 rpm to about 700 rpm. For example, the grinding step may be performed at a rotational speed of about 600 rpm.

[0127] In another example, the grinding step may be carried out for a period of time ranging from about 5 hours to about 20 hours. For example, the grinding step may be carried out for about 10 hours.

[0128] In another example, the grinding step may be performed in a grinding ball:precursor ratio in the range of about 10 to about 30. For example, the grinding step may be performed in a grinding ball:precursor ratio of about 30.

[0129] In some examples, the ratio of grinding balls to precursors is about 30 and the grinding step is carried out at a rotational speed in the range of about 500 rpm to about 700 rpm for about 10 hours to obtain an inorganic compound having the desired argyrodite-like structure. For example, the grinding step is carried out at a rotational speed of about 600 rpm.

[0130] It is understood that the parameters of the grinding step allowing to obtain an inorganic compound having the desired argyrodite type structure (such as, rotation speed, grinding duration, grinding balls: precursors ratio, etc.) can be selected and / or optimized according to the type of grinder used.

[0131] The use of an alkali metal sulfate (e.g., Li2SO4) as a precursor in the process as defined herein could make it possible to obtain an argyrodite-like structure, without an annealing step or with a low-temperature annealing step. In addition, the process as defined herein could make it possible to obtain inorganic compounds having ionic conductivities substantially similar to the ionic conductivities reported for inorganic compounds obtained by conventional processes from different precursors and comprising an annealing step.

[0132] Certain properties of the present inorganic compounds as obtained according to certain embodiments of the present method may also differ from those demonstrated by compounds prepared by conventional methods, for example, by methods using an alkali metal oxide (e.g., Li2O) as a replacement for the alkali metal sulfate (e.g., Li2SO4) as a precursor. For example, according to certain embodiments, the resulting compounds may exhibit greater electrochemical stability, reduced H2S emission, greater critical current density, or reduced polarization compared to conventionally obtained compounds. The inorganic compounds described herein according to certain embodiments may demonstrate greater purity of argyrodite structure by NMR of 6 Li or 31P and / or a reduction in the relative intensity of peaks associated with the PO2S2, PO3S and / or PO4 groups in NMR of 31 P. For example, the relative intensity of the PO2S2, PO3S and PO4 peaks may be below 1.5, below 0.8 and below 0.3, respectively.

[0133] The present technology also relates to an inorganic compound having an argyrodite-type structure as defined herein obtained according to the method as defined herein.

[0134] The present technology also relates to an electrode material comprising an electrochemically active material and an inorganic compound having an argyrodite-type structure as defined herein or obtained according to the method as defined herein.

[0135] According to one example, the inorganic compound having an argyrodite-like structure as defined herein may be present as an additive and / or as a coating material in the electrode material. For example, the inorganic compound having an argyrodite-like structure may form a coating layer on the surface of the electrochemically active material.

[0136] According to another example, said electrode material is a positive electrode material and the electrochemically active material is selected from a metal oxide, a metal sulfide, a metal oxysulfide, a metal phosphate, a metal fluorophosphate, a metal oxyfluorophosphate, a metal sulfate, a metal halide (e.g., a metal fluoride), sulfur, selenium, and a combination of at least two thereof. According to another example, the metal of the electrochemically active material is selected from titanium (Tl), iron (Fe), manganese (Mn), vanadium (V), nickel (Ni), cobalt (Co), aluminum (Al), chromium (Cr), copper (Cu), zirconium (Zr), niobium (Nb), molybdenum (Mo), tungsten (W) and combinations thereof, when compatible. The electrochemically active material may optionally further comprise an alkali or alkaline earth metal, for example, lithium (Li), sodium (Na), potassium (K) or magnesium (Mg).

[0137] Non-limiting examples of electrochemically active materials include lithium and metal phosphates, complex oxides, such as or a combination thereof), is Mn, Co, Ni, or a combination thereof), L or a combination thereof) and their combinations, where compatible.

[0138] According to an example of interest, the electrochemically active material is an oxide as described above. For example, the electrochemically active material may be a lithium manganese oxide, wherein the manganese may be partially substituted by a second transition metal, such as a lithium nickel manganese cobalt (NMC) oxide. According to an alternative embodiment of interest, the electrochemically active material is the

[0139] According to another example, said electrode material is a negative electrode material and the electrochemically active material is selected from a non-alkali and non-alkaline earth metal (e.g., indium (In), germanium (Ge) and bismuth (Bi)), an intermetallic compound (e.g., ), a metal oxide, a metal nitride, a metal phosphide, a metal phosphate (e.g., , a metal halide (e.g., a fluoride of metal), a metal sulfide, a metal oxysulfide, a carbon (e.g., graphite, graphene, reduced graphene oxide, hard carbon, soft carbon, exfoliated graphite, and amorphous carbon), silicon (Si), a silicon-carbon composite (Si-C), a silicon oxide (SIO X ), a silicon oxide-carbon composite (SIOx-C), tin (Sn), a tin-carbon composite (Sn-C), a tin oxide (SnO x), a tin oxide-carbon composite (SnOx-C), and combinations thereof, when compatible. For example, the metal oxide may be selected from compounds of formulas or a combination thereof; and b and c are numbers such that the ratio c:b is in the range 2 to 3) (e.g., MoO3, MoO2, M0S2, ), spinel oxides (e.g., a combination of these) (e.g., a lithium titanate (such as Li4Ti5O12) or a lithium molybdenum oxide According to another example, the electrochemically active material may optionally be doped with other elements included in smaller amounts, for example to modulate or optimize its electrochemical properties. The electrochemically active material may be doped by partial substitution of the metal with other ions. For example, the electrochemically active material may be doped with a transition metal (e.g., Tl, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, W, or Y) and / or a metal other than a transition metal (e.g., Mg, Al, or Sb).

[0140] According to another example, the electrochemically active material may be in the form of particles (e.g., microparticles and / or nanoparticles) which may be freshly formed or commercially sourced. For example, the electrochemically active material may be in the form of particles coated with a layer of coating material. The coating material may be an electronically conductive material, for example, a conductive carbon coating. Alternatively, the coating material may substantially reduce interfacial reactions at the interface between the electrochemically active material and an electrolyte, for example, a solid electrolyte, and in particular, an inorganic solid electrolyte of the sulfide or oxysulfide ceramic type (e.g., based on the inorganic compound having an argyrodite-type structure as defined herein). For example, the coating material may be selected from their combinations, when compatible, and other similar materials. According to an interesting variant, the coating material comprises LiNbO3.

[0141] According to another example, the electrode material as defined herein further includes an electronically conductive material. Non-limiting examples of electronically conductive material include a carbon source such as carbon black (e.g., carbon and Super Carbon ), acetylene black (for example, Shawinigan carbon and Denka carbon black ), graphite, graphene, carbon fibers (e.g., gas-formed carbon fibers (VGCFs)), carbon nanofibers, carbon nanotubes (CNTs), and a combination of two or more of these. In one embodiment, the electronically conductive material is a mixture of carbon black and VGCFs (preferably at a mass ratio in the range of 65:35 to 85:15). According to another example, the electrode material as defined herein further includes an additive. For example, the additive is selected from inorganic ionic conductive materials, inorganic materials, glasses, glass-ceramics, ceramics, including nanoceramics (such as and other similar compounds), salts (e.g., lithium salts) and a combination of at least two of these. For example, the additive may be an inorganic ionic conductor selected from compounds of the LISICON, thio-LISICON, argyrodites, garnets ("ga et" in English), NASICON, perovskites, oxides, sulfides, phosphides, fluorides, sulfur halides, phosphates, thio-phosphates, in crystalline and / or amorphous form, and a combination of at least two of these.

[0142] According to another example, the electrode material as defined herein further includes a binder. For example, the binder is chosen for its compatibility with the various elements of an electrochemical cell. Any known compatible binder is contemplated. For example, the binder may be selected from a polymer binder such as polyether, polyester, polycarbonate, a fluoropolymer, and a water-soluble (water-soluble) binder. According to one example, the binder is a fluoropolymer such as polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE).In another example, the binder is a water-soluble binder such as styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), hydrogenated NBR (HNBR), epichlorohydrin rubber (CHR), or acrylate rubber (ACM), and optionally comprising a thickening agent such as carboxymethylcellulose (CMC), or a polymer such as poly(acrylic acid) (PAA), poly(methyl methacrylate) (PMMA), or a combination thereof. In another example, the binder is a polyether polymer binder. For example, the polyether polymer binder is linear, branched, and / or crosslinked and is based on poly(ethylene oxide) (PEO), poly(propylene oxide) (POP), or a combination of both (such as an EO / PO copolymer), and optionally comprises crosslinkable units.For example, the crosslinkable segment of the polymer may be a polymer segment comprising at least one functional group that can be crosslinked multidimensionally by irradiation or heat treatment.

[0143] The present technology also relates to an electrode comprising an electrode material as defined herein. In one example, the electrode may be on a current collector (e.g., aluminum or copper foil). Alternatively, the electrode may be self-supporting. The present technology also relates to an electrolyte comprising an inorganic compound having an argyrodite-like structure as defined herein or obtained according to the method as defined herein.

[0144] In one example, the electrolyte may be chosen for its compatibility with the various elements of an electrochemical cell. Any type of compatible electrolyte is contemplated. In one example, the electrolyte is a liquid electrolyte comprising a salt in a solvent. In one alternative, the electrolyte is a gel electrolyte comprising a salt in a solvent and optionally a solvating polymer. In another alternative, the electrolyte is a solid polymer electrolyte comprising a salt in a solvating polymer. In another alternative, the electrolyte comprises an inorganic solid electrolyte material, for example, the electrolyte may be a ceramic-type inorganic solid electrolyte. In another alternative, the electrolyte is a polymer-ceramic hybrid solid electrolyte.

[0145] In another example, the solvent, if present in the electrolyte, may be a non-aqueous solvent. Non-limiting examples of solvents include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinylene carbonate (VC); acyclic carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dipropyl carbonate (DPC); lactones such as γ-butyrolactone (γ-BL) and γ-valerolactone (γ-VL); acyclic ethers such as 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), ethoxy methoxy ethane (EME), trimethoxymethane, and ethyl monoglyceride; cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane and dioxolane derivatives;and other solvents such as dimethyl sulfoxide, formamide, acetamide, dimethylformamide, acetonitrile, propylnitrile, nitromethane, phosphoric acid triesters, sulfolane, methylsulfolane, propylene carbonate derivatives and mixtures thereof.;

[0146] In another example, the electrolyte is a gel electrolyte or a gel polymer electrolyte. The gel polymer electrolyte may comprise, for example, a polymer precursor and a salt (e.g., a salt as defined above), a solvent (e.g., a solvent as defined above), and a polymerization and / or crosslinking initiator, if desired. Examples of gel electrolyte include, but are not limited to, gel electrolytes such as those described in PCT patent applications published under numbers WO2009 / 111860 (Zaghib et al.) and WO2004 / 068610 (Zaghib et al.).

[0147] In another example, a gel electrolyte or a liquid electrolyte as defined above may also impregnate a separator such as a polymer separator. Examples of separators include, but are not limited to, polyethylene (PE), polypropylene (PP), cellulose, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polypropylene-polyethylene-polypropylene (PP / PE / PP) separators. For example, the separator is a commercial polymer separator of the type .

[0148] In another example, the electrolyte is a solid polymer electrolyte. For example, the solid polymer electrolyte may be selected from any known solid polymer electrolyte and may be chosen for its compatibility with the various elements of an electrochemical cell. Solid polymer electrolytes generally comprise a salt as well as one or more solid polar polymer(s), optionally crosslinked. Polyether-type polymers, such as those based on polyethylene oxide (PEO), may be used, but several other compatible polymers are also known for the preparation of solid polymer electrolytes and are also contemplated. The polymer may be crosslinked. Examples of such polymers include branched polymers, e.g., star polymers or comb polymers such as those described in PCT patent application published under number WO2003 / 063287 (Zaghib et al.).

[0149] According to another example, the solid polymer electrolyte may include a block copolymer composed of at least one lithium ion solvation segment and optionally at least one crosslinkable segment. Preferably, the lithium ion solvation segment is selected from homo- or copolymers having repeating units of Formula

[0150] Formula I in which,

[0151] According to another example, the crosslinkable segment of the copolymer is a polymer segment comprising at least one functional group crosslinkable multidimensionally by irradiation or heat treatment.

[0152] When the electrolyte is a liquid electrolyte, a gel electrolyte or a solid polymer electrolyte, the inorganic compound having an argyrodite-type structure as defined herein may be present as an additive in the electrolyte.

[0153] When the electrolyte is a polymer-ceramic hybrid solid electrolyte or a ceramic-type inorganic solid electrolyte, the inorganic compound having an argyrodite-type structure as defined herein may be present as the inorganic (ceramic) solid electrolyte material.

[0154] In another example, the electrolyte may also optionally include additional components such as ionically conductive materials, inorganic particles, glass or ceramic particles, and other such additives. The additional component may be chosen for its compatibility with the various elements of an electrochemical cell. In one example, the additional component may be substantially dispersed in the electrolyte. Alternatively, the additional component may be in a separate layer.

[0155] The present technology also relates to an electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein at least one of the positive electrode or the negative electrode is as defined herein or comprises an electrode material as defined herein.

[0156] In one example, the negative electrode is as defined herein or comprises an electrode material as defined herein. For example, the electrochemically active material of the negative electrode may be chosen for its electrochemical compatibility with the various elements of the electrochemical cell as defined herein. For example, the electrochemically active material of the negative electrode material may have a substantially lower oxidation-reduction potential than that of the electrochemically active material of the positive electrode.

[0157] In another example, the positive electrode is as defined herein or comprises an electrode material as defined herein and the negative electrode includes an electrochemically active material selected from any known compatible electrochemically active material. For example, the electrochemically active material of the negative electrode may be selected for its electrochemical compatibility with the various elements of the electrochemical cell as defined herein. Non-limiting examples of electrochemically active materials of the negative electrode include alkali metals, alkaline earth metals, alloys comprising at least one alkali or alkaline earth metal, non-alkali and non-alkaline earth metals (e.g., indium (In), germanium (Ge), and bismuth (Bi)), and alloys or intermetallic compounds (e.g., ). For example, the material electrochemically active material of the negative electrode may be in the form of a film. According to an alternative embodiment, the electrochemically active material of the negative electrode may comprise a film of metallic lithium or an alloy including or based on metallic lithium. According to another example, the positive electrode may be prelithiated and the negative electrode may be initially (i.e., before cycling of the electrochemical cell) substantially or completely free of lithium. The negative electrode may be lithiated in situ during cycling of said electrochemical cell, in particular during the first charge. According to one example, metallic lithium may be deposited in situ on the current collector (for example, a copper current collector) during cycling of the electrochemical cell, in particular during the first charge.According to another example, an alloy including metallic lithium may be generated on the surface of a current collector (e.g., an aluminum current collector) during cycling of the electrochemical cell, in particular during the first charge. It is understood that the negative electrode may be generated in situ during cycling of the electrochemical cell, in particular during the first charge.

[0158] In another example, the positive electrode and the negative electrode are both as defined herein or both comprise an electrode material as defined herein.

[0159] The present technology also relates to an electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein the electrolyte is as defined herein.

[0160] The present technology also relates to an electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein the electrolyte is as defined herein and at least one of the positive electrode or the negative electrode is as defined herein or comprises an electrode material as defined herein.

[0161] In one example, the positive electrode is as defined herein or comprises an electrode material as defined herein.

[0162] The present technology also relates to a battery comprising at least one electrochemical cell as defined herein. For example, the battery may be a primary or secondary battery. According to one example, the battery is selected from the group consisting of a lithium battery, a lithium-ion battery, a sodium battery, a sodium-ion battery, a magnesium battery, a magnesium-ion battery, a potassium battery and a potassium-ion battery. According to a variant of interest, the battery is a so-called all-solid battery. According to one example, the use of an alkali metal sulfate (for example, Li2SO4) as a precursor in the process as defined herein may make it possible to reduce production costs by using a smaller quantity of Li2S and / or by the absence of an annealing step or by reducing the annealing temperature.

[0163] According to another example, the method as defined herein can allow the production of inorganic compounds having ionic conductivities substantially similar to the ionic conductivities reported for inorganic compounds obtained by conventional methods from different precursors and comprising an annealing step.

[0164] According to another example, the process as defined herein can allow the production of inorganic compounds having improved electrochemical stability.

[0165] In another example, the method as defined herein may provide an inorganic compound having improved safety, for example, by substantially reducing the volume of H2S generated by exposure of the inorganic compound to moisture or ambient air.

[0166] According to another example, the method as defined herein can allow obtaining a greater critical current density and therefore better stability in contact with the negative metal or metal alloy electrode.

[0167] EXAMPLES

[0168] The following examples are for illustrative purposes and should not be construed as further limiting the scope of the invention as contemplated. These examples will be better understood by reference to the accompanying Figures.

[0169] Unless otherwise indicated, all numbers expressing component amounts, preparation conditions, concentrations, properties, etc. used herein are to be understood as being modified in all cases by the term "about." At a minimum, each numerical parameter should be interpreted in light of the number of significant figures reported and by applying common rounding techniques. Therefore, unless otherwise indicated, the numerical parameters set forth herein are approximations that may vary depending on the desired properties. Notwithstanding that the ranges of numerical values ​​and the parameters defining the scope of the embodiments are approximations, the numerical values ​​presented in the following examples are reported as accurately as possible.However, any numerical value inherently contains some errors resulting from variations in experiments, test measurements, statistical analyses, etc.

[0170] Example 1 - Synthesis of argyrodites were entirely prepared in a glove box under an inert atmosphere by a solid-state reaction process without heat treatment. The inorganic compounds were obtained by a grinding process from the precursors and at least one halide of Li (LiCI, LiBr and / or LiI) in order to obtain powders having the desired stoichiometries according to the following reaction equations:

[0171] Equation (3)

[0172] Equation (4)

[0173] Equation (5)

[0174] The grinding of the powders was carried out by two different processes.

[0175] First process of brovaae of powders (Process 1):

[0176] The powders were ground using a PULVERISETTE 7 planetary mill. 1.7 g of powder and 15 grinding balls with a diameter of 10 mm made of yttria-containing zirconia (balls:powder mass ratio = 30) were placed in a 45 mL yttria-containing zirconia grinding jar. The powders were ground at a speed of approximately 600 rpm for approximately 10 hours to produce the inorganic compounds with an argyrodite-like structure.

[0177] Second powder grinding process (Process 2): The powder grinding was carried out using a PM 100 planetary mill. 14 g of powder and 16 grinding balls with a diameter of 20 mm made of yttria-containing zirconia (balls:powder mass ratio = 30) were placed in a 250 mL yttria-containing zirconia grinding jar. The powders were ground at a speed of about 650 rpm for about 10 hours to produce the inorganic compounds with an argyrodite-type structure.

[0178] Example 2 - X-ray diffraction (XRD) characterization of inorganic compounds with an argyrodite-type structure

[0179] The crystal structure of the argyrodites prepared in Example 1 was studied by XRD. The analysis was carried out entirely in an anhydrous chamber and the X-ray spectra were obtained using a Rigaku X-ray diffractometer equipped with a cobalt X-ray source.

[0180] Pellets were prepared by compressing 80 mg of argyrodite powder prepared in Example 1. The pellets were then placed in sealed sample holders which were closed in a glove box under an inert atmosphere.

[0181] In the X-ray diffraction patterns shown in Figures 1 to 6, the peaks corresponding to the impurities were identified by solid lines, dashed lines, and em-dot-dot lines, respectively. The “D” peak originates from the dome used in the XRD analysis. The other peaks correspond to the argyrodite-type structure.

[0182] Figure 1 presents the X-ray diffraction patterns obtained for the argyrodites (Argyrodites 1 to 4 and 8). The X-ray diffraction patterns presented in Figure 1 show that the argyrodite-like structure is indeed obtained for all compositions. It is possible to observe the presence of a substantially larger amount of impurities for the compositions richest in oxygen (y > 0.3) (Argyrodites 3 and 4).

[0183] Figure 2 shows the X-ray diffraction patterns obtained for Argyrodites 2 and 5 to 7. Figure 2 shows that the argyrodite structure was indeed obtained for t = 1.3 and y = 0.3 (Argyrodites 5 and 6), and this, for both syntheses (Equations 3 and 4). It is possible to observe in Figure 2, the presence of less residual Li2S for the structure of Argyrodite 6 than for the structure of Argyrodite 5. Figure 2 also shows a degradation of the structure for argyrodite of formula in which, t = 1.6 and y = 0.3 (Argyrodite 7). A substantially larger amount of residual LiCI can be observed, but no trace of Li2S. This indicates that an argyrodite-like structure including less lithium could induce a mixture of argyrodite-like phases and parasitic phases (e.g., LiCI).

[0184] Figure 3 presents the X-ray diffraction patterns for argyrodites obtained from the precursors Li2SO4 (Argyrodites 2 and 3) and Li2O (Argyrodites 9 and 10). Figure 3 shows that for an oxygen content of 0.3 (Argyrodites 2 and 9) there is no significant difference observable on the structure of argyrodite from the inorganic compounds obtained from the two different precursors. However, for an oxygen content of 0.5 the argyrodite prepared from Li2O (Argyrodite 10) contains substantially more impurities (notably LiCl) and has a substantially less well-defined structure compared to the argyrodite prepared from Li2SO4 (Argyrodite 3). Thus, it is possible to obtain substantially purer oxidized argyrodites over a wide composition range from the Li2SO4 precursor compared to the commonly used Li2O precursor.

[0185] Figure 4 presents the X-ray diffraction patterns for argyrodites obtained from the precursor Li2SO4 and a mixture of halide compounds including LiCl and LiBr (Argyrodites 12 to 14) compared to those of the same compositions obtained from LiCl (Argyrodite 2) or LiBr (Argyrodite 15). Figure 4 shows that the argyrodite structure is well preserved regardless of the Br and Cl content. The position of the peaks decreases with increasing Br content. This can be attributed to the increase in the lattice parameter, a phenomenon known in the literature.

[0186] Figure 5 shows the X-ray diffraction patterns for argyrodites obtained from the precursor Li2SO4 and a mixture of halides including LiCl, LiBr and LiI (Argyrodites 16 to 19). Figure 5 shows that the argyrodite structure is well preserved even with the mixture of the three halides.

[0187] It is thus possible to obtain a compound having an oxidized argyrodite structure regardless of the composition and the halide mixture with oxidation from the precursor Li2SO4.

[0188] Figure 6 shows the X-ray diffraction patterns for Argyrodites 2 and 13 obtained from the precursor Li2SO4 in small volume jars (according to Method 1 presented in ('Example 1) and Argyrodites 20 and 21 obtained from the precursor Li2SO4 in larger volume jars (according to Method 2 presented in ('Example 1). The composition of Argyrodites 2 and 20 are similar as well as those of argyrodites 13 and 21. Figure 5 shows that the argyrodite structure is well preserved whatever the composition of the argyrodite and whatever the synthesis volume demonstrating that the process thus described could be applied on an industrial scale.

[0189] Example 3 - Nuclear magnetic resonance (NMR) characterization of inorganic compounds with an argyrodite-type structure

[0190] The composition of the argyrodites prepared in Example 1 was studied by NMR. The nuclear magnetic resonance spectra of lithium ( 6 Li NMR) and phosphorus ( 31 P NMR) were obtained by the MAS (magic angle spinning) technique using a Bruker Avance NEO 500 MHz spectrometer equipped with a 4 mm triple resonance probe with a maximum magic angle spinning speed of 15 kHz.

[0191] Figures 7 and 8 respectively present spectra 6 Li NMR and 31 P NMR obtained for argyrodites of composition obtained from the precursors

[0192] For both argyrodites (Argyrodites 2 and 9), the main peak on the NMR spectra 6Li shown in Figure 7 corresponds to argyrodite, while the secondary peak corresponds to LiCl residues.

[0193] For Argyrodites 2 and 9, the main peak on the NMR spectra 31 P presented in Figure 8 corresponds to argyrodite, while the secondary peaks correspond to the phases . The relative intensity of the NMR peaks 31 P is shown in Table 1.

[0194] Table 1. Relative intensity of NMR peaks 31 P

[0195] The relative intensity of the peaks presented in Table 1 shows that the use of Li2SO4 as a precursor (Argyrodite 2) significantly reduces the formation of the secondary phases PO2S2, PO3S and PO4 compared to the use of Li2O (Argyrodite 9). It is therefore possible to observe that oxygen is better incorporated into the argyrodite structure thanks to the precursor Li2SO4 and therefore generates fewer additional phases. This makes it possible to differentiate an argyrodite synthesized from Li2SO4 from an argyrodite prepared from Li2O or any other source of oxygen as a precursor.

[0196] Figures 9 and 10 respectively present spectra 6 Li NMR and 31 P NMR obtained for argyrodite of formula obtained from Li2SO4 precursors (Argyrodite 7).

[0197] It is possible to observe on the spectrum 6Li NMR shown in Figure 9 a peak at 1.2 ppm corresponding to an argyrodite phase with six lithiums and one chlorine, a second peak at 0.2 ppm corresponding to an argyrodite phase with a structure having an excess of chlorine and a third peak at -1.1 ppm corresponding to LiCl.

[0198] It is possible to observe on the spectrum 31 P NMR shown in Figure 10 a main peak corresponding to argyrodite and three secondary peaks corresponding to phases of Figure 10 also shows an enlargement of the peak main showing that it decomposes into three peaks corresponding to one (P1), two (P2) and three (P3) chlorine in the secondary structure of phosphorus. The simultaneous excess of P1 and P3 confirms the presence of two types of argyrodites, with a low and a high chlorine fraction.

[0199] Thus, a substantial decrease in lithium levels can lead to the presence of at least two phases of argyrodites.

[0200] Figures 11 and 12 respectively present spectra 6 Li NMR and 31 P NMR obtained for argyrodites of formula (Argyrodite 13) and of formula (Argyrodite 16) obtained from the precursor Li2SO4. The main peak on the NMR spectra 6 Li presented in Figure 11 corresponds to argyrodite. It is possible to observe on the spectra 31 P NMR presented in Figure 12 a main peak corresponding to argyrodite and the presence of weak secondary peaks corresponding to phases of This confirms the results obtained by X-ray diffraction, namely the obtaining of a pure oxidized argyrodite phase from Li2SO4 regardless of the halide composition.

[0201] Example 4 - H2S Generation Upon Exposure of Inorganic Compounds with Argyrodite-Type Structure to Air Safety tests were conducted to assess the impact of argyrodite on H2S generation. Approximately 10 mg (± 3 mg) of argyrodite powder was placed in a sealed cell under an inert atmosphere.

[0202] An air flow was introduced into the sealed cell at a flow rate of approximately 0.3 L / min, at a controlled temperature of approximately 24.5 °C (± 0.5 °C) and at a controlled hygrometry with a humidity level of 50% (± 5%). The concentration of H2S gas generated was measured approximately every 15 seconds with a multigas detector (MSA ALTAIR MC 5X) previously calibrated and placed at the outlet of the cell. From these data, the volume of H2S gas generated normalized by the mass of argyrodite was calculated.

[0203] The results of these analyses are presented in Figure 13. Figure 13 shows a graph of the volume of H2S gas generated per gram of argyrodite powder (mL / g) versus time (hours) for Argyrodites 2 (dotted line), (em dash-dot line), (dashed line), 11 (solid line), 13 (line dash dot dot) and 16 (line small dash) prepared in Example 1.

[0204] It can be observed that a classical LiePSsCI type argyrodite (Argyrodite 11) generates a substantially higher volume of gaseous H2S than a chlorine-doped argyrodite of the (Argyrodite 8), demonstrating the safety benefits of chlorine doping. It can also be observed that argyrodites based on the precursor also allow the volume of gaseous H2S to be reduced as This is the case for argyrodite (Argyrodite 2). Adding bromine and / or iodine from the previous composition while maintaining the same oxygen and lithium content further reduces H2S generation. Finally, Figure 13 shows that an argyrodite-type structure generated from the Li2SO4 precursor with a significant decrease in lithium (Argyrodite 7) further reduces the volume of gaseous H2S generated, and thus improves safety while reducing production costs through a lower quantity of Li2S used and the absence or reduction of the annealing step.

[0205] Example 5 - Ionic Conductivity of Inorganic Compounds Having an Argyrodite-Type Structure a) Preparation of Symmetrical Cells for Ionic Conductivity Measurements Symmetrical cells were assembled according to the following procedure in order to measure the ionic conductivity of inorganic compounds having an argyrodite-type structure prepared in ('Example 1.

[0206] Pellets were prepared by compressing 160 mg of inorganic compound powder having an argyrodite-type structure prepared in Example 1 between two stainless steel electrodes under a pressure of 360 MPa. The pellets placed between two stainless steel electrodes were then assembled in sealed conductivity cells closed in a glove box under an inert atmosphere maintained at a pressure of 20 MPa.

[0207] The symmetrical cells were assembled according to the configurations shown in Table 2.

[0208] Table 2. Symmetrical cell configurations b) Measurement of the ionic conductivity of symmetrical cells

[0209] The ionic conductivity measurements of the symmetrical cells assembled in Example 5(a) were carried out with a VMP-300 multichannel potentiostat (BioLogic). The measurements were carried out in the frequency range from 7 MHz to 200 mHz under an amplitude of 50 mV in a temperature range from -10°C to 70°C (up and down, each 10°C).

[0210] Each ionic conductivity measurement was obtained after approximately one hour of stabilization of the oven temperature at the temperature. The ionic conductivity was extracted based on the equivalent circuit used to extract the resistance associated with the measured pellet. The straight lines were obtained for the symmetrical cells prepared in Example 5(a). The slope of these straight lines corresponds to the activation energy and has a value of approximately 0.3 eV.

[0211] Figure 14 shows the results of measured ionic conductivity as a function of temperature for the Cells It can be observed in Figure 14 that the ionic conductivity of the most oxygen-poor argyrodites (y ≤ 0.3) (Cells 1 and 2) is similar to that of the oxide-free argyrodite (Cell 8). A decrease in conductivity is observed for the most oxygen-rich argyrodites (y > 0.3) (Cells 3 and 4). It is noteworthy that the ionic conductivity of the argyrodite of formula (Cell 2) prepared from Li2SO4 is substantially identical to that of oxide-free argyrodite (Cell 8).

[0212] Figure 15 shows the results of measured ionic conductivity as a function of temperature for the Cells . Figure 15 shows substantially similar ionic conductivity values ​​for Cells 5 and 6 comprising Argyrodites 5 and 6, respectively (t = 1.3 and y = 0.3) obtained by two different syntheses (Equations (3) and (4), respectively). For t = 1.6 and y = 0.3, Figure 15 also shows substantially lower ionic conductivity values ​​for Cell 7 comprising Argyrodite 7 compared to those for Cell 2 comprising Argyrodite 2. As can be observed, thanks to the Li2SO4 precursor, it is possible to modulate the composition (e.g., the lithium, oxygen, and sulfur content) of an oxysulfurized lithium argyrodite while remaining substantially within the same ionic conductivity range. It is also possible to observe that a significant lithium deficiency induces a reduction in ionic conductivity.

[0213] Figure 16 shows the results of measured ionic conductivity as a function of temperature for the Cells. Figure 16 shows that for the same composition, the ionic conductivity of argyrodites obtained from the Li2SO4 precursor (Argyrodites 2 and 3) is significantly higher than that of argyrodites obtained from the Li2O precursor (Argyrodites 9 and 10). As demonstrated in Figure 8, the use of Li2SO4 type precursor allows a better incorporation of oxygen within the argyrodite structure and this results in an increase in conductivity as demonstrated by the results in Figure 16.

[0214] Figure 17 shows the results of measured ionic conductivity as a function of temperature for the Cells . Figure 17 shows that composition modulation from the two halogens (i.e., chlorine and bromine) does not substantially change the ionic conductivity, while maintaining high conductivities. It is noted that Argyrodite 14 exhibits the best conductivity.

[0215] Figure 18 shows the results of measured ionic conductivity as a function of temperature for the Cells . Figure 18 shows that the incorporation of the three halogens (i.e., chlorine, bromine, and iodine) in the presence of Li2SO4 does not substantially alter the ionic conductivity, while maintaining high conductivities. It can be observed that an iodine level of 0.1 allows better conductivity to be obtained than at a higher level.

[0216] Thus, by combining the different analyses, thanks to the Li2SO4 precursor, it is possible to obtain oxysulfurized argyrodites with the same ionic conductivities as those without oxide and improved compared to the use of the Li2O precursor. In addition, it is possible to modulate the composition of Li2SO4-based argyrodites with different rates and types of halide while maintaining high ionic conductivity. In addition, this modulation improves safety while maintaining good conduction properties.

[0217] Figure 19 shows the results of measured ionic conductivity as a function of temperature for the Cells. Figure 19 shows that regardless of the composition of the Li2SO4-based argyrodite, the increase in synthesis volume allows a slight increase in ionic conductivity. This demonstrates that the proposed solutions can be easily applied on an industrial scale, without loss of performance. Example 6 - Electrochemical stability of inorganic compounds with an argyrodite-type structure a) Preparation of pseudo-batteries for electrochemical stability measurements

[0218] Pseudo-batteries were assembled according to the following procedure to determine the electrochemical stability of Argyrodites 2 and 9 prepared in Example 1.

[0219] 5% by mass of VGCFs were mixed with 95% by mass of Argyrodites 2 and 9 in order to obtain composite pseudo-positive electrodes, and thus observe redox reactions substantially representative of the final compositions of composite positive electrodes that can be used in battery configuration.

[0220] Solid electrolytes composed of the same argyrodites were then placed on the surface of the composite pseudo-positive electrodes. Negative electrodes of metallic lithium were then deposited on the surface of the solid electrolytes.

[0221] The assemblies comprising a composite pseudo-positive electrode, a solid electrolyte and a metallic lithium negative electrode were then compressed and assembled in sealed cells closed in a glove box under an inert atmosphere.

[0222] The pseudo-batteries were assembled according to the configurations shown in Table 3.

[0223] Table 3. Pseudo-battery configurations b) Cyclic voltammetry The electrochemical stability in oxidation of the pseudo-batteries as described in Example 6(a) was measured using a VMP-300 multichannel potentiostat (BioLogic).

[0224] Figure 20 shows the cyclic voltammetry results obtained for Cell 22 and for Cell 23 (comparative battery) recorded at a scan rate of 0.05 mV / s in the potential range of lithium, nickel, manganese and cobalt (NMC) oxide, i.e. between 2.5 V and 4.3 V vs Li / Li* at a temperature of approximately 30 °C. Figure 20 shows the results obtained during the first four cycles for each of the two pseudo-batteries.

[0225] Figure 20 shows that no reaction with lithium metal could be observed, demonstrating the chemical and electrochemical stability of argyrodites with lithium metal. In the NMC potential range, it is possible to observe a weak redox reaction for both pseudo-batteries, with a lower current density generated for Cell 22 comprising argyrodite obtained using Li2SO4 as a precursor (0.3 pA / cm 2) and lower polarization hysteresis. It is also possible to observe that this reaction is reversible. Argyrodites would therefore be substantially electrochemically stable in the NMC potential range with substantially improved electrochemical stability for argyrodite obtained using Li2SO4 as a precursor. Thus, argyrodite obtained using Li2SO4 as a precursor is substantially stable over the entire potential range of a lithium metal battery.

[0226] Example 7 - Electrochemical properties of inorganic compounds having an argyrodite-type structure

[0227] The electrochemical properties of Argyrodite 2 prepared in Example 1 were studied. a) Preparation of composite positive electrode material

[0228] 35% by mass of Argyrodite 2 powder prepared in Example 1 was mixed with 65% by mass of particles of and 5% by mass of a mixture of Li400 carbon black and VGCFs (75:25 mass ratio). The powders dry materials were mixed using a vortex mixer and then mixed with mortar to homogenize the composite positive electrode material. b) Electrochemical cell configuration (Cell 24)

[0229] The electrochemical cell was assembled according to the following procedure.

[0230] A solid electrolyte was prepared by placing 80 mg of argyrodite 2 powder prepared in Example 1 into a 10 mm diameter mold under a pressure of 200 MPa. 13 mg of the composite positive electrode material prepared in Example 7(a) was then added into the mold on top of the solid electrolyte followed by an aluminum current collector. The contents of the mold including the solid electrolyte layer, the composite positive electrode layer and the aluminum current collector were then compressed under a pressure of 360 MPa for about 10 minutes. A 10 mm diameter lithium metal electrode on a stainless steel current collector was then added opposite the solid electrolyte layer and the assembly was compressed under a pressure of 120 MPa for about 5 minutes.

[0231] The electrochemical cell was then assembled in a sealed cycling cell closed in a glove box under an inert atmosphere maintained at a pressure of 20 MPa. c) Electrochemical behavior of the electrochemical cell

[0232] Cell 24 assembled in Example 7(b) was cycled between 2.5 V and 4.3 V vs Li / Li*. The first five cycles were performed at C / 10, followed by four cycles at C / 4, and then the aging experiments were performed at a constant charge and discharge current of C / 2 at a temperature of 30°C for a surface capacity of 1.8 mAh / cm 2 .

[0233] Figure 21 shows a graph of charge and discharge capacity and the coulombic efficiency (A) as a function of the number of cycles per 100 cycles.

[0234] Figures 22 and 23 show the discharge profiles at different charge and discharge currents. Specifically, Figures 22 and 23 show a plot of potential versus discharge capacity and time in hours, respectively.

[0235] It can be observed that at C / 10, C / 4 and C / 2 the electrochemical cell provides a capacity of approximately 170 mAh.g' respectively 1 , 160 mAh.g' 1 and 150 mAh.g' 1 .

[0236] It is possible to observe a substantial capacity retention after 100 cycles, thus allowing the stability of the performances in aging as demonstrated in Figure 22. It is possible to observe an adequate cyclability of the electrochemical cell at C / 2 in charge and discharge at a temperature of 30°C demonstrating the good electrochemical stability of Argyrodite 2 in potential and with respect to the electronic conductive material (i.e., the mixture of carbon black Li400 and VGCFs) and the electrochemically active material (i.e., NCM).

[0237] Several modifications could be made to any of the embodiments described above without departing from the scope of the present invention as contemplated. The references, patents or scientific literature documents referred to in this application are incorporated herein by reference in their entirety and for all purposes.

Claims

DEMANDS 1. A process for preparing an inorganic compound having an argyrodite-type structure based on an alkali metal, the process comprising a step of grinding alkali metal sulfide, alkali metal sulfate, phosphorus pentasulfide and an alkali metal halide, wherein the alkali metal is selected from lithium, sodium and potassium, for example, the alkali metal is lithium.

2. A method according to claim 1, wherein the alkali metal halide is selected from alkali metal fluoride, alkali metal chloride, alkali metal bromide, alkali metal iodide and a mixture of at least two of these.

3. A process according to claim 2, wherein the alkali metal halide is the alkali metal chloride. A process according to claim 2, wherein the alkali metal halide is the alkali metal bromide.

5. A process according to claim 2, wherein the alkali metal halide is the alkali metal iodide.

6. A process according to claim 2, wherein the alkali metal halide is a mixture of alkali metal chloride and alkali metal bromide.

7. A process according to claim 2, wherein the alkali metal halide is a mixture of alkali metal chloride, alkali metal bromide and alkali metal iodide.

8. A method according to any one of claims 1 to 7, wherein the argyrodite-type structure is of formula in which M is the alkali metal chosen from Li, Na and K, e.g. M is Li, Z is a halogen atom chosen from F, Cl, Br and I, x denotes the number of Z atoms in excess of 1 or is equal to zero, and y is a non-zero number (e.g. 0 ≤ x ≤ 1 and 0 < y ≤ 1).

9. Method according to claim 8, wherein x is a non-zero number (e.g., 0 < x ≤ 1).

10. Method according to claim 8 or 9, wherein x and y are selected to achieve electroneutrality.

11. A method according to any one of claims 8 to 10, wherein the argyrodite-type structure is selected from inorganic compounds having an argyrodite-type structure of formulas in which M is as defined in claim 8.

12. A method according to any one of claims 8 to 10, wherein the argyrodite-type structure is selected from inorganic compounds having an argyrodite-type structure of formulas 13. A method according to any one of claims 1 to 7, wherein the argyrodite-type structure has the formula in which M is the metal alkali chosen from Li, Na and K, for example M is Li, Z is a halogen atom chosen from F, Cl, Br and I, x denotes the number of Z atoms in excess of 1 or is equal to zero, and y is a non-zero number (for example, 0 ≤ x ≤ 1 and 0 < y ≤ 1).

14. Method according to claim 13, wherein x is a non-zero number (e.g., 0 < x ≤ 1).

15. A method according to claim 13 or 14, wherein the argyrodite-type structure is selected from inorganic compounds having an argyrodite-type structure of formulas in which M is as defined in claim 13.

16. A method according to claim 15, wherein the argyrodite-type structure is selected from inorganic compounds having an argyrodite-type structure of formulas 17. A method according to any one of claims 1 to 16, wherein the grinding step is carried out using a grinder.

18. Method according to claim 17, wherein the mill is a planetary mill.

19. A method according to any one of claims 1 to 18, wherein the grinding step is carried out at a rotational speed in the range of approximately 300 rpm to approximately 800 rpm.

20. A method according to any one of claims 1 to 18, wherein the grinding step is carried out at a rotational speed in the range of approximately 400 rpm to approximately 700 rpm.

21. A method according to any one of claims 1 to 18, wherein the grinding step is carried out at a rotational speed in the range of approximately 500 rpm to approximately 700 rpm.

22. A method according to any one of claims 1 to 18, wherein the grinding step is carried out at a rotational speed of about 600 rpm.

23. A method according to any one of claims 1 to 22, wherein the grinding step is carried out for a duration in the range of about 5 hours to about 20 hours.

24. A method according to any one of claims 1 to 22, wherein the grinding step is carried out for approximately 10 hours.

25. A method according to any one of claims 1 to 24, wherein the grinding step is carried out in a grinding ball:precursor ratio in the range of about 10 to about 30.

26. A method according to any one of claims 1 to 24, wherein the grinding step is carried out in a grinding ball: precursor ratio of about 30.

27. A method according to any one of claims 1 to 26, further comprising an annealing step carried out at a maximum temperature of about 400 °C.

28. A method according to any one of claims 1 to 26, further comprising an annealing step carried out at a maximum temperature of about 300 °C.

29. A method according to any one of claims 1 to 26, which is exempt from an annealing step.

30. An inorganic compound having an argyrodite-type structure obtained according to the process as defined in any one of claims 1 to 29.

31. An electrode material comprising an electrochemically active material and an inorganic compound having an argyrodite-type structure as defined in claim 30 or obtained according to the process as defined in any one of claims 1 to 29.

32. Electrode material according to claim 31, in which the inorganic compound having an argyrodite-type structure is present as an additive.

33. Electrode material according to claim 31 or 32, wherein the inorganic compound having an argyrodite-type structure is present as a coating material.

34. Electrode material according to claim 33, wherein the coating material forms a coating layer on the surface of the electrochemically active material.

35. Electrode material according to any one of claims 31 to 34, wherein the electrochemically active material is selected from a metal oxide, a metal sulfide, a metal oxysulfide, a metal phosphate, a metal fluorophosphate, a metal oxyfluorophosphate, a metal sulfate, a metal halide, a metal fluoride, sulfur, selenium and a combination of at least two of these.

36. Electrode material according to claim 35, wherein the metal of the electrochemically active material is selected from titanium (Ti), iron (Fe), manganese (Mn), vanadium (V), nickel (Ni), cobalt (Co), aluminium (Al), chromium (Cr), copper (Cu), zirconium (Zr), niobium (Nb), molybdenum (Mo), tungsten (W) and a combination of at least two of these.

37. Electrode material according to claim 35 or 36, wherein the metal of the electrochemically active material further comprises an alkali or alkaline earth metal selected from lithium (Li), sodium (Na), potassium (K) and magnesium (Mg).

38. Electrode material according to any one of claims 31 to 37, wherein the electrochemically active material is a metal and lithium oxide.

39. Electrode material according to claim 38, wherein the metal and lithium oxide is a mixed oxide of lithium, nickel, manganese and cobalt (NCM).

40. Electrode material according to any one of claims 31 to 34, wherein the electrochemically active material is selected from a non-alkali or non-alkaline earth metal, an intermetallic compound, a metal oxide, a metal nitride, a metal phosphide, a metal phosphate, a metal halide, a metal fluoride, a metal sulfide, a metal oxysulfide, carbon, silicon (Si), a silicon-carbon composite (Si-C), or silicon dioxide (SiO₂). X ), a silicon-carbon oxide composite (SiOx-C), tin (Sn), a tin-carbon composite (Sn-C), a tin oxide (SnO x ), a tin-carbon oxide composite (SnOx-C), and a combination of at least two of these.

41. Electrode material according to any one of claims 31 to 40, wherein the electrochemically active material further comprises a doping element.

42. Electrode material according to any one of claims 31 to 41, wherein the electrochemically active material further comprises a coating material.

43. Electrode material according to claim 42, wherein the coating material is an electronically conductive material.

44. Electrode material according to claim 43, wherein the electronically conductive material is carbon.

45. Electrode material according to claim 42, wherein the coating material is selected from other similar coating materials and a combination of at least two of these.

46. ​​Electrode material according to claim 45, wherein the coating material is LINbO3.

47. Electrode material according to any one of claims 31 to 46, further comprising at least one electronically conductive material.

48. Electrode material according to claim 47, wherein the electronically conductive material is selected from the group consisting of carbon black, acetylene black, graphite, graphene, carbon fibers, carbon nanofibers, carbon nanotubes, and a mixture of at least two of these.

49. Electrode material according to claim 48, wherein the electronically conductive material is a mixture of carbon black and gas-formed carbon fibers (VGCFs).

50. Electrode material according to any one of claims 31 to 49, further comprising at least one additive.

51. Electrode material according to claim 50, wherein the additive is selected from inorganic ionic conducting materials, inorganic materials, glasses, glass-ceramics, ceramics, nano-ceramics, salts and a combination of at least two of these.

52. Electrode material according to any one of claims 31 to 51, further comprising a binder.

53. Electrode material according to claim 52, wherein the binder is selected from the group consisting of a polymer binder of the polyether, polycarbonate or polyester type, a fluorinated polymer and a water-soluble binder.

54. An electrode comprising the electrode material as defined in any one of claims 31 to 53 on a current collector.

55. A self-supporting electrode comprising the electrode material as defined in any one of claims 31 to 53.

56. An electrolyte comprising an inorganic compound having an argyrodite-type structure as defined in claim 30 or obtained according to the process as defined in any one of claims 1 to 29.

57. Electrolyte according to claim 56, said electrolyte being a liquid electrolyte comprising a salt in a solvent.

58. Electrolyte according to claim 56, said electrolyte being a gel electrolyte comprising a salt in a solvent and optionally a solvating polymer.

59. Electrolyte according to claim 56, said electrolyte being a solid polymer electrolyte comprising a salt in a solvating polymer.

60. Electrolyte according to any one of claims 56 to 59, wherein the inorganic compound having an argyrodite-type structure is present as an additive.

61. Electrolyte according to claim 56, said electrolyte being an inorganic solid electrolyte.

62. Electrolyte according to claim 56, said electrolyte being a solid hybrid polymer-ceramic electrolyte.

63. Electrolyte according to claim 61 or 62, wherein the inorganic compound having an argyrodite-type structure is present as an inorganic solid electrolyte material.

64. Electrolyte according to any one of claims 56 to 63, further comprising at least one additional component.

65. Electrolyte according to claim 64, wherein the additional component is selected from ionic conducting materials, inorganic particles, glass or ceramic particles and a combination of at least two of these.

66. An electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein at least one of the positive or negative electrodes is as defined in claim 54 or 55 or comprises an electrode material as defined in any one of claims 31 to 53.

67. An electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein the electrolyte is as defined in any one of claims 56 to 65.

68. Electrochemical cell according to claim 66 or 67, wherein the negative electrode comprises an electrochemically active material comprising an alkali metal, an alkaline earth metal, an alloy comprising at least one alkali or alkaline earth metal, a non-alkaline and non-alkaline earth metal, or an intermetallic alloy or compound.

69. Electrochemical cell according to claim 68, wherein the electrochemically active material of the negative electrode comprises metallic lithium or an alloy including or based on metallic lithium.

70. Electrochemical cell according to any one of claims 66 to 68, wherein the positive electrode is pre-lithiumized and the negative electrode is substantially lithium-free.

71. Electrochemical cell according to claim 70, wherein the negative electrode is lithiased in situ during the cycling of said electrochemical cell.

72. An electrochemical accumulator comprising at least one electrochemical cell as defined in any one of claims 66 to 71.

73. Electrochemical accumulator according to claim 72, wherein said electrochemical accumulator is a battery selected from a lithium battery, a lithium-ion battery, a sodium battery, a sodium-ion battery, a magnesium battery, and a magnesium-ion battery.

74. Electrochemical accumulator according to claim 73, wherein said battery is a lithium battery or a lithium-ion battery.

75. Electrochemical accumulator according to any one of claims 72 to 74, wherein said electrochemical accumulator is a so-called all-solid battery.

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