Sulfidic solid electrolyte and its precursor ii

Abstract

To provide a rapid, easy and cost-effective method for producing a homogeneous solid electrolyte having excellent electrical properties, for example, high ionic conductivity and electrochemical stability.SOLUTION: Provided is a solid electrolyte precursor represented by the following formula (I): Li(2a-n)Yn+Sa (I), wherein Y is independently selected from P, As, Ge, Sn, B, Si, Al, Ga and Sb, 4≤n≤5, and 4≤a≤6, preferably 4.8≤a≤5.2, in particular Li5PS5, Li5AsS5, Li4GeS4, Li4SiS4, Li3BS3, Li4SnS4, Li3GaS3, Li3AlS3, Li5SbS5, or mixtures thereof, for example physical mixtures, mixed crystals and / or solid solutions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to solid electrolytes, their precursors, methods for their preparation and their use in, for example, electrochemical cells and capacitors, fuel cells, batteries and sensors. [Background technology]

[0002] Solid electrolytes offer high ion mobility within an otherwise rigid crystalline structure. They are particularly suitable for applications in batteries, fuel cells, and sensors because their specific structure replaces the additional liquid or membrane that normally separates the electrodes. In this way, the health and safety risks associated with hazardous or flammable organic liquid electrolytes are avoided. Furthermore, the solid electrolytes have been shown to have excellent electronic properties, such as high ionic conductivity and electrochemical stability.

[0003] A particularly relevant group of solid electrolytes for electrochemical storage devices are cationic solid electrolytes that provide mobile lithium ions, such as lithium argyrodite-type solid electrolytes, in particular sulfide lithium argyrodite-type solid electrolytes, of the general formula Li 12-m-x + M m+ S 6-x 2- X x - [In the formula, M m+ =Si 4+ , Ge 4+ , Sn 4+ , P 5+ , As 5+ ; X - =Cl - , Br - , I - ; 0≦x≦2].

[0004] International Publication No. 2009 / 047254 (WO2009 / 047254 A1) describes a method for producing the sulfide lithium argyrodite having the formula Li6PS5Z, where Z is selected from Cl, Br and I, which method comprises the steps of mixing solid reactants including Li2S, P2S5 and a halogen source under an inert gas atmosphere, pressurizing the mixture, and subsequently heating the resulting compact.

[0005] US Patent Application Publication No. 2018 / 0358653 (US2018 / 0358653 A1) discloses a method for producing a solid electrolyte having an argyrodite-type crystal structure, which includes kneading raw materials containing lithium, sulfur, phosphorus, and halogen as constituent elements, followed by heat treatment.

[0006] A drawback of the above solid-phase synthesis is that the kneading or mixing step does not ensure homogeneous distribution of the reactants throughout the raw material to be heated. Thus, the resulting solid electrolyte contains impurities of accumulated unreacted starting materials and / or has a heterogeneous structure due to the formation of secondary phases of different composition, which impairs the electronic properties of the electrolyte.

[0007] International Publication No. 2018 / 054709 (WO2018 / 054709 A1) discloses a method for preparing a solid electrolyte based on lithium, phosphorus and sulfur, such as Li4PS4I, by mixing the reactants in an organic solvent and heating in an inert gas atmosphere.

[0008] Although solvent-based methods result in a more homogeneous distribution of reactants than solid-phase-based methods, they require costly and time-consuming separation, drying, and washing steps to remove the organic solvent from the reaction product. Furthermore, residual solvent molecules can interfere with the electronic properties of the solid electrolyte, for example, reducing its ionic conductivity.

[0009] In view of the above, there is an urgent need for new methods for producing solid electrolytes that overcome the drawbacks of known methods and allow for the provision of improved solid electrolyte materials. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] International Publication No. 2009 / 047254 [Patent Document 2] US Patent Application Publication No. 2018 / 0358653 [Patent Document 3] International Publication No. 2018 / 054709 Summary of the Invention [Problem to be solved by the invention]

[0011] It is therefore an object of the present invention to provide a fast, easy and cost-effective method for producing homogeneous solid electrolytes with excellent electrical properties, such as high ionic conductivity and electrochemical stability. [Means for solving the problem]

[0012] Surprisingly, Eq. Li (2a - n) Y n+ S a (I) [In the formula, Y is independently selected from P, As, Ge, Sn, B, Si, Al, Ga, and Sb; 3≦n≦5, preferably 4≦n≦5, and 3≦a≦6, preferably 4≦a≦6 with an X-containing lithium salt, Li (2b + c - m) Y m+ Sb X c (II) [In the formula, X is independently selected from Group 17 elements, e.g., Cl, Br, I; Y is independently selected from P, As, Ge, Sn, B, Si, Al, Ga, and Sb; 3≦m≦5, preferably 4≦m≦5, 3≦b≦6, more preferably 4≦b≦6, and 0≦c≦2], or Li (8-q*(1-t)-r*(t)) Y' q+ 1-t Y'' r+ t S4(III) [In the formula, Y' is independently selected from Si and Ge; Y'' is independently selected from P, Al, Sn, Ga, and Sb; 3≦q≦5, 2≦r≦6, 0≦t≦1] It has been found that this makes it possible to provide an improved solid electrolyte having high purity and homogeneity, as represented by

[0013] In the solid electrolyte precursor of formula (I), Y is preferably one or more of P, As, Ge, Sn, B, Si, Al, Ga and Sb in their respective oxidation states, such as P 5+ , As 5+ , Ge 4+ , Sn 4+ , B 3+ , Si 4+ , Al 3+ , Ga 3+ and Sb 5+ In a preferred embodiment, Y is independently selected from P 5+ , As 5+ and / or Ge 4+ is.

[0014] The stoichiometric ratio of S can be 4.8≦a≦5.2. In a more preferred embodiment, a is 4 or 5.

[0015] n is in the range of 3≦n≦5, preferably 4≦n≦5. In particular, n is 5.

[0016] The precursor according to the present invention is preferably selected from Li5PS5, Li5AsS5, Li4GeS4, Li4SiS4, Li3BS3, Li4SnS4, Li3GaS3, Li3AlS3, Li5SbS5, more preferably Li5PS5, Li5AsS5, Li4GeS4, Li4SiS4, Li4SnS4, Li5SbS5, or mixtures thereof, such as physical mixtures, mixed crystals, and / or solid solutions.

[0017] The solid electrolyte precursor has at least a partially ordered atomic arrangement and is preferably partially crystalline or in a crystalline state, especially in a crystalline state, and the atomic arrangement of the precursor can be determined by conventional means known in the art, such as X-ray diffraction (XRD).

[0018] In a preferred embodiment, the solid electrolyte precursor is in the form of a pure phase, the presence of which can be detected by X-ray diffraction (XRD), as known to those skilled in the art.

[0019] In particular, the solid electrolyte precursor according to the invention has the following 2θ angles [°] corresponding to the reflections of undesired impurities: CuK α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0020] The term "substantially free of reflections" in the sense of the present invention means that the reflections at each 2θ angle have an intensity of at most 5%, preferably at most 2%, more preferably at most 1% of the most intense product reflection recorded for each compound. A "characteristic reflection" in the sense of the present invention is a reflection having an intensity of at least 40%, preferably at least 50%, more preferably at least 60% of the most intense reflection recorded for each compound.

[0021] The solid electrolyte precursor according to the present invention has improved product homogeneity and purity, eg, free of unreacted starting materials and compositionally different secondary phases.

[0022] The precursor may further comprise at least one dopant. A dopant in the sense of the present invention is an auxiliary element introduced into the (crystalline) structure of the solid electrolyte precursor, e.g., to change its electrical properties, and is preferably present in an amount of less than 10% by weight, more preferably 0.01-9.0% by weight, and even more preferably 0.10-5.0% by weight, relative to the total weight of the precursor. The type of dopant as well as its concentration significantly influences the resulting material properties. Suitable dopants are, for example, Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, O, Se, Te, Mg, Na, Ca, Sb, B, Ga, or mixtures thereof, in their respective oxidation states. B, As, Se, and Ni, in their respective oxidation states, more preferably B, are preferred. 3+ , As 5+ , Se 2- and Ni 2+ Dopants selected from are particularly useful for enhancing ionic conductivity or for enabling mixed electronic and ionic conduction.

[0023] In a further aspect, the present invention provides a method for producing a solid electrolyte precursor according to the present invention, comprising the steps of: (i) providing a lithium salt in a reaction vessel; (ii) contacting at least one sulfur-containing reactant gas with the lithium salt of step (i) at an elevated temperature; (iii) contacting at least one Y-containing component with the product obtained in step (ii) at elevated temperature; and (iv) optionally discharging the product obtained in step (iii) wherein in step (iii) the Y-containing component is at least partially in a gas phase.

[0024] In step (i), a lithium salt is provided, preferably LiOH, Li2CO3, Li2SO4, Li2O, Li2O2, or a mixture thereof, more preferably LiOH. The lithium salt may further contain water of crystallization and / or water not incorporated into its crystalline structure, preferably Li2SO4·H2O or LiOH·H2O. The overall water content of the lithium salt provided in step (i) may be 0-50% by weight, for example 10-45% by weight. In a preferred embodiment, the lithium salt is substantially water-free, for example having a water content of less than 5% by weight, preferably 0.01-1% by weight, more preferably less than 0.1% by weight.

[0025] Optionally, step (i) is preceded by a step of pre-drying the lithium salt at elevated temperature, for example at least 80°C, preferably 90 to 250°C, optionally under reduced pressure, i.e. below atmospheric pressure (<1013 mbar), for example below 500 mbar, for example 0.001 to 100 mbar. Such pre-dried lithium salt may be substantially water-free, for example having a water content of less than 5% by weight, preferably 0.01 to less than 1% by weight, more preferably less than 0.1% by weight.

[0026] Step (i) and optionally the pre-drying step can be carried out under a dry air or inert gas atmosphere, such as N, He or Ar. Preferably, the inert gas or dry air is substantially water-free, i.e. has a relative humidity (RH) of less than 10%, preferably 5% by volume, more preferably 0.02 to 2%.

[0027] In step (ii), the lithium salt of step (i) is contacted with at least a sulfur-containing reaction gas at elevated temperature, for example above 80°C, preferably from 90 to 250°C.

[0028] Step (ii) may be carried out under a dry air or inert gas atmosphere, such as N, He or Ar, wherein said inert gas or dry air is preferably substantially water-free, i.e., has a RH of less than 10%, preferably less than 5%, more preferably less than 2%. When both steps (i) and (ii) are carried out under an inert gas or dry air atmosphere, said gases may be (essentially) the same.

[0029] The sulfur-containing reaction gas is preferably selected from H2S, S8, CS2, mercaptans or mixtures thereof, and is preferably H2S.

[0030] In a preferred embodiment, the sulfur-containing reaction gas is substantially water-free, i.e., has an RH of less than 10%, preferably less than 5%, more preferably 0.01-2%. The sulfur-containing reaction gas may further comprise a carrier gas. Suitable carrier gases are inert and can be selected from dry air and inert gases known in the art, such as N2, He, or Ar, preferably dry air or N2, and are particularly substantially water-free, i.e., have an RH of less than 10% by volume, preferably less than 5% by volume, more preferably 0.01-2% by volume. Preferably, the carrier gas corresponds to the gas applied in step (i).

[0031] The molar ratio in step (ii) of S in the sulfur-containing reaction gas, preferably H2S, to Li in the lithium salt provided in step (i) is preferably 1:1 to 1:10, more preferably 1:1 to 1:5, even more preferably 1:2.

[0032] The product obtained in step (ii) is contacted at elevated temperature with a Y-containing component, preferably a sulfide of Y, more preferably P2S5, As2S5, GeS2, SnS2, B2S3, SiS2, Al2S3, Ga2S3, Sb2S5 or mixtures thereof.

[0033] The Y-containing component is preferably substantially water-free, ie, has less than 10% RH by volume, preferably less than 5% RH by volume, more preferably 0.01 to 2% RH by volume.

[0034] In a preferred embodiment, step (ii) is carried out at a total gas flow rate of 0.1 to 1000 m 3 / h, preferably 5 to 500m 3 / h, preferably 15 to 50 m 3 / h, where the total gas flow rate includes at least one sulfur-containing reaction gas and a carrier gas, as appropriate. The total gas flow rate may depend, inter alia, on the amount of lithium salt provided in step (i), the type of precursor to be obtained, and the reaction temperature. Furthermore, the total gas flow rate may also depend on the amount of water formed as a by-product in step (ii), since in order to completely convert the lithium salt in step (ii), it is essential to remove the water, i.e., by the gas flow through the reaction vessel.

[0035] According to the present invention, the Y-containing component is at least partially present in gaseous form. Step (iii) is preferably carried out at a temperature above 285°C, preferably between 288 and 1200°C, more preferably between 288 and 900°C. The Y-containing component may further comprise a carrier gas. Suitable carrier gases are inert and can be selected from dry air and inert gases known in the art, such as N2, He, or Ar, preferably dry air or N2, and are particularly essentially water-free, i.e., have an RH content of less than 10% by volume, preferably less than 5% by volume, more preferably 0.01 to 2% by volume. Preferably, the carrier gas corresponds to the carrier gas applied in step (i) and / or step (ii), as appropriate.

[0036] In a preferred embodiment, the molar ratio of the Y-containing component, e.g., Y in P2S5, to lithium in the lithium salt provided in step (i) is 1:1 to 1:10, preferably 1:3 to 1:6, more preferably about 1:5.

[0037] In a preferred embodiment, step (iii) is carried out at a total gas flow rate of 0.1 to 1000 m 3 / h, preferably 5 to 500m 3 / h, preferably 15 to 50 m 3 / h, where the total gas flow rate includes at least one Y-containing component in gaseous state, if present, and a carrier gas, if applicable. The total gas flow rate may depend, inter alia, on the amount of lithium salt provided in step (i), the precursor to be obtained, and the reaction temperature. Furthermore, the total gas flow rate may also depend on the amount of water formed as a by-product in step (ii), since in order to completely convert the lithium salt in step (ii), it is essential to remove said water, for example, by gas flow through the reaction vessel.

[0038] Furthermore, the amount of by-product water can also serve as a reaction control to determine the time point of (essentially) complete conversion of the lithium salt in step (ii). By this means, the duration of step (ii) can be individually adapted to the reaction conditions. Preferably, the duration of step (ii) is up to 24 hours, for example 15 minutes to 15 hours, depending on the individual reaction conditions.

[0039] The method according to the invention may further comprise, prior to step (iii), a step (ii.1) of adding at least one doping agent to the product of step (ii). The doping agent may be an anionic or cationic doping agent. Cationic doping agents may include Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, O, Se, Te, Mg, Na, Ca, Sb, B and Ga in their respective oxidation states. Anionic doping agents may include O 2- , Se 2- or Te2- The doping agent may be present in liquid, solid or gaseous form. Preferably, the doping agent is present in solid form, for example in the form of a salt. Suitable cationic doping agents are, for example, hydroxides, carbonates or sulfide salts, such as As2S5, Ni(OH)2 or Mg(CO3), or mixtures thereof. Suitable anionic doping agents are, for example, lithium salts, such as Li2O, Li2Se or Li2Te, or mixtures thereof. Step (ii.1) may further comprise mixing the product obtained in step (ii) with at least one doping agent by comminution means, for example by ball milling or stirring as known in the art.

[0040] Optionally, the product obtained after such a doping step is transported out of the reaction vessel. In other embodiments, the product obtained in step (ii) or the product obtained after the doping step is left in the reaction vessel and further reacted to provide the solid electrolyte described herein.

[0041] The method of the present invention may further comprise a step (iii.1) of adding at least one doping agent to the product obtained in step (iii). The doping agent is preferably an anionic or cationic doping agent. Preferred cationic doping agents include Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, O, Se, Te, Mg, Na, Ca, Sb, B and Ga in their respective oxidation states. Anionic doping agents are O 2- , Se 2- , or Te 2-The doping agent can be present in liquid, solid or gaseous form. Preferably, the doping agent is present in solid form, for example in the form of a salt. Suitable cationic doping agents are, for example, hydroxides, carbonates or sulfide salts, such as As2S5, Ni(OH)2 or Mg(CO3), or mixtures thereof. Suitable anionic doping agents are, for example, lithium salts, such as Li2O, Li2Se or Li2Te, or mixtures thereof. Step (iii.1) may further comprise mixing the product obtained in step (iii) with at least one doping agent by comminution means, for example by ball milling or stirring as known in the art.

[0042] The amount of doping agent added to the product obtained in step (ii.1) or (iii.1) depends, for example, on the type of doping agent and the amount of product obtained in step (ii) or step (iii), and in particular the amount of dopant in the solid electrolyte is less than 10% by weight, preferably 0.01 to 9.0% by weight, more preferably 0.10 to 5.0% by weight, relative to the total weight of the solid electrolyte precursor.

[0043] Optionally, the product obtained after such a doping step is transported out of the reaction vessel. In other embodiments, the product obtained in step (iii) or the product obtained after the doping step is left in the reaction vessel and further reacted to provide the solid electrolyte described herein.

[0044] To provide a suitable reaction atmosphere, such as an inert gas or dry air, during step (i) and / or step (ii), and / or step (iii), the reaction vessel may be sealed and isolated from the environment, while at least one gas inlet and at least one gas outlet may allow for the controlled introduction and removal of gases, such as dry air, inert gas, reaction gas, carrier gas, and / or water vapor, into and from the vessel, respectively. Suitable reaction vessels are, for example, heatable fluidized bed reactors known in the art.

[0045] The solid electrolyte precursor according to the present invention can be used to produce a solid electrolyte, in particular a sulfide solid electrolyte.

[0046] In particular, the solid electrolyte has the formula (II): Li (2b + c - m) Y m+ S b X c (II) [In the formula, X is independently selected from Group 17 elements, e.g., Cl, Br, and I; Y is independently selected from P, As, Ge, Sn, B, Si, Al, Ga, and Sb; 3≦m≦5, preferably 4≦m≦5, 3≦b≦6, preferably 4≦b≦6, and 0≦c≦2] or represented by formula (III): Li (8-q*(1-t)-r*t) Y' q+ 1-t Y'' r+ t S4(III) [In the formula, Y' is independently selected from Si and Ge; Y'' is independently selected from P, Al, Sn, Ga, and Sb; 3≦q≦5 2≦r≦6 0≦t≦1] is expressed by

[0047] Preferably, the solid electrolyte is represented by formula (II):

[0048] X is independently selected from Group 17 elements (i.e., halogens), preferably F, Cl, Br, and I, more preferably Cl, Br, and I. In one embodiment, X is F or Cl or Br or I, preferably Cl or Br or I. In another embodiment, X is a mixture of at least two Group 17 elements, such as a mixture of Cl and Br, a mixture of Cl and I, or a mixture of Br and I, in which the ratio of element X1 to element X2 is 0.01:0.99 to 0.99:0.01, preferably 0.1:0.9 to 0.9:0.1, more preferably 0.3:0.7 to 0.7:0.3, such as X=(Cl 0.5 Br 0.5 ) c is.

[0049] Y m+ is preferably P 5+ , As 5+ , Ge 4+ , Sb 5+ , Sn 4+ , B 3+ , Si 4+ , Al 3+ and Ga 3+ are independently selected from

[0050] Y' q+ is preferably Ge 4+ and Si 4+ are independently selected from

[0051] Y'' r+ is preferably P 5+ , Al 3+ , Sn 4+ , Ga 3+ and Sb 5+ are independently selected from

[0052] Preferred solid electrolytes that can be produced by the precursor according to the present invention include Li6PS5X [wherein X is independently selected from Cl, Br, and I], Li3PS4, Li7P3S 11 , Li 10 YP2S 12[wherein Y is independently selected from Si, Sn and Ge], more preferably Li3PS4, Li7P3S 11 , Li 10 YP2S 12 wherein Y is independently selected from Si, Sn, and Ge.

[0053] The homogeneity and purity of the product can be determined by conventional means known in the art, such as powder X-ray diffraction (XRD). α A typical XRD pattern of a solid electrolyte according to the present invention recorded using a line will have predominant product reflections, with few, if any, reflections due to impurities, such as by-products and unreacted starting materials.

[0054] In a preferred embodiment, the solid electrolyte is in the form of a pure phase. The presence of a pure phase can be detected by X-ray diffraction (XRD), as known to those skilled in the art.

[0055] In particular, the solid electrolyte according to the invention has a 2θ angle [°] corresponding to the reflection of undesired impurities: CuK α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0056] In a preferred embodiment, the solid electrolyte according to the invention has a 2θ angle [°] corresponding to the reflection of undesired impurities: CuK α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0057] In a preferred embodiment, the solid electrolyte according to the invention has a 2θ angle [°] corresponding to the reflection of undesired impurities: CuK αIt has substantially no reflections in powder X-ray diffraction using X-rays.

[0058] In a preferred embodiment, the solid electrolyte according to the invention has a 2θ angle [°] corresponding to the reflection of undesired impurities: CuK α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0059] In a preferred embodiment, the solid electrolyte according to the invention has a 2θ angle [°] corresponding to the reflection of undesired impurities: CuK α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0060] In a preferred embodiment, the solid electrolyte according to the invention has a 2θ angle [°] corresponding to the reflection of undesired impurities: CuK α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0061] In a preferred embodiment, the solid electrolyte according to the invention has a 2θ angle [°] corresponding to the reflection of undesired impurities: CuK α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0062] In a preferred embodiment, the solid electrolyte according to the invention has a 2θ angle [°] corresponding to the reflection of undesired impurities: CuK α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0063] In a preferred embodiment, the solid electrolyte according to the invention has a 2θ angle [°] corresponding to the reflection of undesired impurities: CuK α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0064] In a preferred embodiment, the solid electrolyte according to the invention has a 2θ angle [°] corresponding to the reflection of undesired impurities: CuK α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0065] In a further aspect, the present invention provides a method for producing a pharmaceutical composition comprising: (a) providing a solid electrolyte precursor according to the present invention in a reaction vessel; (b) contacting at least one X-containing lithium salt and / or S-containing lithium salt and / or Y-containing sulfide with the solid electrolyte precursor of step (a) at elevated temperature; and (c) optionally discharging the product obtained in step (b); The present invention relates to a method for producing a solid electrolyte, including:

[0066] Preferably, step a) is preceded by the method for producing a solid electrolyte precursor according to the invention, in particular step a) is followed by step (iii).

[0067] Step a) can be carried out under a dry air or inert gas atmosphere, such as N, He, or Ar. Preferably, the inert gas or dry air is substantially water-free, i.e., has a relative humidity (RH) of less than 10% by volume, preferably 5% by volume, more preferably 0.02 to 2% by volume. In a preferred embodiment, the reaction vessel is sealed during step a) and / or step b).

[0068] In step b), the solid electrolyte precursor of step a) can be contacted with an X-containing lithium salt at elevated temperature. The X-containing lithium salt is preferably used to prepare the solid electrolyte of formula (II). The X-containing lithium salt contains a Group 17 element, such as fluorine, chlorine, bromine, and iodine, more preferably chlorine, bromine, and iodine, even more preferably chlorine and bromine, and even more preferably chlorine. In a preferred embodiment, the X-containing lithium salt is lithium chloride, lithium bromide, lithium iodide, or a mixture thereof. Preferably, the X-containing lithium salt is substantially water-free, i.e., has an RH of less than 10% by weight, preferably less than 5% by weight, and more preferably 0.01-2% by weight.

[0069] In step b), the solid electrolyte precursor of step a) can be contacted with an S-containing lithium salt at elevated temperature. S-containing lithium salts are preferably used to prepare the solid electrolyte of formula (II) when c<1. In a preferred embodiment, the S-containing lithium salt is lithium sulfide. Preferably, the S-containing lithium salt is substantially water-free, i.e., has an RH of less than 10 wt.%, preferably less than 5 wt.%, more preferably 0.01-2 wt.%.

[0070] In step b), the solid electrolyte precursor of step a) can be contacted with a Y-containing sulfide at elevated temperature. The Y-containing sulfide is preferably used to prepare the solid electrolyte of formula (III). The Y-containing sulfide is preferably P2S5. Preferably, the Y-containing sulfide is substantially water-free, i.e., has an RH of less than 10% by weight, preferably less than 5% by weight, more preferably 0.01 to 2% by weight.

[0071] At least one X-containing lithium salt and / or S-containing lithium salt and / or Y-containing sulfide may be contacted with said solid electrolyte precursor in a fluidized bed reactor or the like by conventional means, for example by stirring.

[0072] The temperature maintained in step b) is above 80°C, preferably between 90 and 700°C.

[0073] The molar ratio of X in the X-containing lithium salt or S in the S-containing lithium salt to the solid electrolyte precursor provided in step a) may be 0.01:1 to 3:1, preferably 0.1:1 to 2:1, more preferably 1:1.

[0074] The molar ratio of Y in the Y-containing sulfide to the solid electrolyte precursor prepared in step a) may be 0.01:1 to 6:1, preferably 0.1:1 to 6:1, more preferably 1:1 or 4:1.

[0075] The duration of step b) may be up to 48 hours, for example from 15 minutes to 30 hours, depending on the particular reaction conditions.

[0076] To provide a suitable reaction atmosphere, such as an inert gas or dry air atmosphere, during step (a) and / or step (b), the reaction vessel may be sealed and isolated from the environment, while at least one gas inlet and at least one gas outlet allow for controlled introduction and removal of gas, such as dry air, inert gas, into and from the vessel, respectively. The reaction vessel may be a fluidized bed reactor as known in the art.

[0077] In one embodiment, the product obtained in step (b) is discharged from the reaction vessel.

[0078] The present invention also encompasses the above-described method for preparing a solid electrolyte, further comprising the step of adding at least one doping agent, such as an anionic or cationic doping agent, to the product obtained in step (b). The cationic doping agent may comprise Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, O, Se, Te, Mg, Na, Ca, Sb, B, Ga, or a mixture thereof, in each oxidation state. The anionic doping agent may comprise O 2- , Se 2- , or Te 2-The doping agent may be present in liquid, solid or gas form. Preferably, the doping agent is present in solid form, for example, in the form of a salt. Suitable cationic doping agents are, for example, hydroxides, carbonates or sulfide salts, such as As2S5, Ni(OH)2 or Mg(CO3), or mixtures thereof. Suitable anionic doping agents are, for example, lithium salts, such as Li2O, Li2Se or Li2Te, or mixtures thereof.

[0079] The amount of doping agent added to the product obtained in step (b) depends, for example, on the type of doping agent and the amount of product obtained in step (b), and in particular the amount of dopant in the solid electrolyte is less than 10% by weight, preferably 0.01-9.0% by weight, more preferably 0.10-5.0% by weight, relative to the total weight of said solid electrolyte.

[0080] The step of adding at least one doping agent may further include mixing the product obtained in step (b) with the at least one doping agent by grinding, for example, by ball milling, or by stirring as known in the art. Preferably, the step of adding at least one doping agent is carried out when the solid electrolyte precursor prepared in step (a) does not contain a dopant.

[0081] In a further aspect, the present invention relates to a solid electrolyte obtained by the method according to the present invention. In contrast to solid electrolytes obtained by methods known in the art, such as solid-based or solvent-based methods, the solid electrolytes obtained by the method according to the present invention have improved product homogeneity and purity, and are free of unreacted starting materials and intermediate phases. This approach results in solid electrolytes with improved electrical properties, such as improved ionic conductivity and electrochemical stability. Preferably, the solid electrolytes obtained by the above method have an ionic conductivity of 0.01 to 500 mS / cm, preferably 1 to 100 mS / cm, at 20°C.

[0082] In another aspect, the present invention relates to an electrochemical cell comprising the above-described solid electrolyte.

[0083] The present invention is further illustrated, but not limited, by the following examples. [Brief explanation of the drawings]

[0084] [Figure 1] XRD pattern of Li6PS5Cl measured over the 2θ range 5–90° using CuKα radiation and shown as relative intensity Irel. Peaks marked with # are due to the sample holder. [Example]

[0085] Example 1 100.0 g of LiOH·HO with a total water content of 42% by mass was heated in a fluidized bed reactor at 150 °C for 1 h. The pre-dried lithium salt was then mixed with a reaction gas containing P2S5 and H2S in a molar ratio of 1:5, as well as nitrogen as a carrier gas at a content of 95% by volume relative to the total amount of gas, at a total gas flow rate of 18 m 3 / h for 1 hour at 150° C. to give a solid electrolyte precursor.

[0086] The solid electrolyte was then contacted with solid lithium chloride salt at 400° C., where the molar ratio of LiCl to solid electrolyte precursor was 1:1.

[0087] The resulting solid electrolyte has a stoichiometric composition of Li:P:S:Cl = 6:1:5:1 and an ionic conductivity of 4.5 mS / cm at room temperature, measured using electrochemical impedance spectroscopy in the frequency range of 1 MHz to 100 Hz at a Metrohm Autolab under an inert gas atmosphere. Sample pellets were prepared by crushing the solid electrolyte powder and filling a 13 mm diameter pressure sample cell equipped with stainless steel electrodes. The pressure applied during the measurements was p = 3 T.

[0088] Powder X-ray diffraction analysis was performed using a Bruker D2 PHASER diffractometer.α The scan was performed over the 2θ range of 5 to 90° with a step width of 0.020°.

[0089] The respective powder patterns are shown in Figure 1 and show characteristic reflections at 2θ angles [°]: 25.53, 30.04 and 31.41, and no reflections at 2θ angles [°]: 17.53, 18.05, 32.52, 34.88, 44.81, 46.66, 50.17 and 53.10.

[0090] The present invention includes the following aspects: 1. The following formula (I): Li (2a - n) Y n+ S a (I) [In the formula, Y is independently selected from P, As, Ge, Sn, B, Si, Al, Ga, and Sb; 3≦n≦5, preferably 4≦n≦5, and 3≦a≦6, preferably 4≦a≦6] A solid electrolyte precursor represented by

[0091] 2. The precursor according to item 1, wherein 4.8≦a≦5.2.

[0092] 3. Y n+ P 5+ , As 5+ , Ge 4+ , Si 4+ , B 3+ , Sn 4+ , Ga 3+ , Al 3+ and Sb 5+ 3. The precursor according to item 1 or 2, independently selected from:

[0093] 4. The precursor according to any one of items 1 to 3, selected from Li5PS5, Li5AsS5, Li4GeS4, Li4SiS4, Li3BS3, Li4SnS4, Li3GaS3, Li3AlS3, Li5SbS5, or mixtures thereof, such as physical mixtures, mixed crystals and / or solid solutions.

[0094] 5. A precursor according to any one of items 1 to 4, further comprising at least one dopant.

[0095] 6. The precursor according to item 5, wherein the dopant is selected from Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, O, Sb, B, Ga, Se, O, Te, Mg, Na, Ca, or mixtures thereof in their respective oxidation states.

[0096] 7. The precursor according to item 5 or 6, wherein the dopant is present in an amount of less than 10% by weight, preferably 0.01 to 9.0% by weight, more preferably 0.10 to 5.0% by weight, relative to the total weight of the precursor.

[0097] 8. A precursor according to any one of items 1 to 7, in a crystalline or partially crystalline state, more preferably in the form of a pure phase.

[0098] 9. A method for producing a solid electrolyte precursor according to any one of items 1 to 8, comprising: (i) providing a lithium salt in a reaction vessel; (ii) contacting the sulfur-containing reaction gas with the lithium salt of step (i) at elevated temperature; (iii) contacting a Y-containing component with the product obtained in step (ii) at elevated temperature; and (iv) optionally discharging the product obtained in step (iii) wherein the Y-containing component is at least partially in a gas phase.

[0099] 10. The method according to item 9, wherein the lithium salt has a water content of 0 to 50% by mass, preferably 0 to 10% by mass.

[0100] 11. The method according to item 9 or 10, wherein step (i) is preceded by a step of pre-drying the lithium salt at elevated temperature, for example at least 80°C, preferably 90 to 250°C, optionally under reduced pressure.

[0101] 12. The method according to any one of items 9 to 11, wherein the lithium salt in step (i) is LiOH, Li2CO3, Li2SO4, Li2O, Li2O2, or a mixture thereof.

[0102] 13. The method according to any one of items 9 to 12, wherein step (i) and / or step (ii) and / or step (iii) are carried out under dry air or an inert gas atmosphere, for example under an N2, He or Ar atmosphere.

[0103] 14. The method according to item 13, wherein the inert gas or dry air is substantially free of water.

[0104] 15. The method according to any one of items 9 to 14, wherein step (ii) is carried out at a temperature above 80°C, preferably from 90 to 250°C.

[0105] 16. The method according to any one of items 9 to 15, wherein the sulfur-containing reaction gas is selected from H2S, S8, CS2, mercaptans or mixtures thereof.

[0106] 17. The method according to any one of items 9 to 16, wherein step (iii) is carried out at a temperature above 285°C, preferably between 288 and 1200°C.

[0107] 18. The method of any one of items 9 to 17, wherein the Y-containing component is selected from P2S5, As2S5, GeS2, SiS2, B2S3, SnS2, Ga2S3, Al2S3, Sb2S5, or mixtures thereof.

[0108] 19. The method of any one of items 9 to 18, wherein the sulfur-containing reaction gas and the Y-containing component are substantially water-free.

[0109] 20. The method according to any one of items 9 to 19, wherein in step (ii), the molar ratio of S in the sulfur-containing reaction gas, particularly H2S, to Li in the lithium salt prepared in step (i) is 1:1 to 1:10, preferably 1:1 to 1:5, more preferably about 1:2.

[0110] 21. The method according to any one of items 9 to 20, wherein in step (iii), the molar ratio of the Y-containing component, particularly Y in P2S5, to Li in the lithium salt prepared in step (i) is 1:1 to 1:10, preferably 1:3 to 1:6, and more preferably about 1:5.

[0111] 22. The method of any one of items 9 to 21, wherein the sulfur-containing reaction gas further comprises a carrier gas.

[0112] 23. The method of any one of items 9 to 22, wherein the Y-containing component further comprises a carrier gas.

[0113] 24. Step (ii) is carried out at a total gas flow rate of 0.1 to 1000 m 3 / h, preferably 5 to 500m 3 / h, preferably 10 to 50 m 3 24. The method according to any one of items 9 to 23, wherein the method is carried out for 10 min at 2000 x g / h.

[0114] 25. Step (iii) is performed for a total gas flow rate of 0.1 to 1000 m 3 / h, preferably 5 to 500m 3 / h, preferably 10 to 50 m 3 25. The method according to any one of items 9 to 24, wherein the method is carried out for 10 min at 2000 x g / h.

[0115] 26. The method according to any one of items 9 to 25, further comprising a step (ii.1) prior to step (iii) of adding at least one doping agent, such as a cationic or anionic doping agent, to the product obtained in step (ii).

[0116] 27. The method according to any one of items 9 to 26, further comprising a step (iii.1) of adding at least one doping agent, such as an anionic or cationic doping agent, to the product obtained in step (iii).

[0117] 28. The method according to item 26 or 27, wherein the at least one doping agent is provided in the form of a salt.

[0118] 29. Use of a solid electrolyte precursor according to any one of items 1 to 8 for producing a solid electrolyte, in particular a sulfide solid electrolyte.

[0119] 30. The solid electrolyte has the following formula (II): Li (2b + c - m) Y m+ S b X c (II) [In the formula, X is independently selected from Group 17 elements, e.g., Cl, Br, and I; Y is independently selected from P, As, Ge, Sn, B, Si, Al, Ga, and Sb; 3≦m≦5, preferably 4≦m≦5, 3≦b≦6, preferably 4≦b≦6, and 0≦c≦2] Item 29. The use according to item 29, represented by

[0120] 31. The solid electrolyte has the following formula (III): Li (8-q*(1-t)-r*t) Y' q+ 1-t Y'' r+t S4(III) [In the formula, Y' is independently selected from Si and Ge; Y'' is independently selected from P, Al, Sn, Ga, and Sb; 3≦q≦5, 2≦r≦6, 0≦t≦1] Item 29. The use according to item 29, represented by

[0121] 32. The solid electrolyte is Li3PS4, Li7P3S 11 , or Li 10 YP2S 12 Item 30. The use according to item 29, wherein Y is independently selected from Si, Sn and Ge.

[0122] 33. (a) Providing a solid electrolyte precursor according to any one of items 1 to 8 in a reaction vessel; (b) contacting at least one X-containing lithium salt and / or S-containing lithium salt and / or Y-containing sulfide with the solid electrolyte precursor of step (a) at elevated temperature; and (c) optionally discharging the product obtained in step (b); A method for producing a solid electrolyte, comprising:

[0123] 34. The method according to item 33, wherein step (a) and / or step (b) are carried out under a dry air or inert gas atmosphere, such as an N2, He or Ar atmosphere.

[0124] 35. The method of claim 34, wherein the inert gas is substantially free of water.

[0125] 36. The method according to any one of items 33 to 35, wherein step (b) is carried out at a temperature above 80°C, preferably 90 to 700°C.

[0126] 37. The method according to any one of items 33 to 36, wherein the X-containing lithium salt is a halide, such as LiCl, LiBr, LiI or a mixture thereof, preferably LiCl or LiBr, and / or the S-containing lithium salt is preferably Li2S, and / or the Y-containing sulfide is preferably P2S5.

[0127] 38. The method according to any one of items 33 to 37, wherein in step (b), the molar ratio of X in the X-containing lithium salt or S in the S-containing lithium salt to the solid electrolyte precursor prepared in step (a) is 0.01:1 to 3:1.

[0128] 39. The method of any one of items 33 to 38, wherein the X-containing component is substantially water-free.

[0129] 40. The method according to any one of items 33 to 39, further comprising a step (b.1) of adding at least one doping agent, such as an anionic or cationic doping agent, to the product obtained in step (b).

[0130] 41. The method of claim 40, wherein the at least one doping agent is provided in the form of a salt.

[0131] 42. A solid electrolyte obtained by the method according to any one of items 33 to 41.

[0132] 43. An electrochemical cell comprising the solid electrolyte according to item 42.

Claims

1. Formula (I): Li (2a - n) Y n+ S a (I) [In the formula, Y is independently selected from P, As, Ge, Sn, B, Si, Al, Ga, and Sb; 4≦n≦5, and 4≦a≦6, preferably 4.8≦a≦5.2] In particular, Li 5 P.S. 5 , Li 5 AsS 5 , Li 4 GeS 4 , Li 4 SiS 4 , Li 3 B.S. 3 , Li 4 SnS 4 , Li 3 GaS 3 , Li 3 AIS 3 , Li 5 SbS 5 or mixtures thereof, such as physical mixtures, mixed crystals and / or solid solutions.

2. 10. The precursor of claim 1, further comprising at least one dopant, such as Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, O, Sb, B, Ga, Se, O, Te, Mg, Na, Ca, or mixtures thereof in their respective oxidation states.

3. A method for producing the solid electrolyte precursor according to claim 1 or 2, comprising: (i) a lithium salt, preferably LiOH, Li 2 CO 3 , Li 2 SO 4 , Li 2 O, Li 2 O 2 or providing a mixture thereof in a reaction vessel; (ii) a sulfur-containing reactive gas, such as H 2 S, S 8 , C.S. 2 contacting the mercaptan, mercaptan or mixture thereof with the lithium salt of step (i) at elevated temperature, e.g., 90-250°C; (iii) Y-containing components, such as P 2 S 5 , As 2 S 5 , GeS 2 , SiS 2 , B 2 S 3 , SnS 2 , Ga 2 S 3 , Al 2 S 3 , Sb 2 S 5 or a mixture thereof with the product obtained in step (ii) at elevated temperature, e.g., 288-1200°C; and (iv) optionally discharging the product obtained in step (iii). wherein the Y-containing component is at least partially in a gas phase.

4. In step (ii), a sulfur-containing reaction gas, in particular H 2 4. The method of claim 3, wherein the molar ratio of S in S to Li in the lithium salt provided in step (i) is 1:1 to 1:10, preferably 1:1 to 1:5, more preferably about 1:

2.

5. In step (iii), the Y-containing component, particularly P 2 S 5 5. The method of claim 3 or 4, wherein the molar ratio of Y to Li in the lithium salt provided in step (i) is from 1:1 to 1:10, preferably from 1:3 to 1:6, more preferably about 1:

5.

6. Step (ii) and / or step (iii) are carried out at a total gas flow rate of 0.1 to 1000 m 3 / h, preferably 5 to 500 m 3 / h, more preferably 10 to 50 m 3 6. The method according to claim 3, wherein the process is carried out for 10 min. / h.

7. Solid electrolytes, in particular sulfide solid electrolytes, in particular those of the following formula (II): Li (2b + c - m) Y m+ S b X c (II) [In the formula, X is independently selected from Group 17 elements, e.g., Cl, Br, and I; Y is independently selected from P, As, Ge, Sn, B, Si, Al, Ga, and Sb; 4≦m≦5, 4≦b≦6, and 0≦c≦2] or the following formula (III): fi) (8-q*(1-t)-r*t) `' q+ 1-t `'' r+ t 3 4 (_=) [In the formula, Y' is independently selected from Si and Ge; Y″ is independently selected from P, Al, Sn, Ga, and Sb; 3≦q≦5, 2≦r≦6, 0≦t≦1] 3. Use of the solid electrolyte precursor according to claim 1 or 2 for producing a solid electrolyte represented by:

8. The solid electrolyte is Li 3 P.S. 4 , Li 7 P 3 S 11 , or Li 10 YP 2 S 12 8. The use according to claim 7, wherein Y is independently selected from Si, Sn and Ge.

9. (a) providing a solid electrolyte precursor according to any one of claims 1 to 8 in a reaction vessel; (b) contacting at least one X-containing lithium salt and / or S-containing lithium salt and / or Y-containing sulfide with the solid electrolyte precursor of step (a) at an elevated temperature, for example, 90-700°C; and (c) optionally discharging the product obtained in step (b). A method for producing a solid electrolyte, comprising:

10. The X-containing lithium salt is a halide, such as LiCl, LiBr, LiI or a mixture thereof, preferably LiCl or LiBr, and / or the S-containing lithium salt is preferably Li 2 S, and / or the Y-containing sulfide is preferably P 2 S 5 The method of claim 9, wherein

11. 11. The method according to claim 9 or 10, wherein in step (b), the molar ratio of X in the X-containing lithium salt or S in the S-containing lithium salt to the solid electrolyte precursor provided in step (a) is 0.01:1 to 3:

1.

12. 12. The method according to any one of claims 9 to 11, further comprising a step (b.1) of adding at least one doping agent, such as an anionic or cationic doping agent, preferably in the form of a salt, to the product obtained in step (b).

13. A solid electrolyte obtainable by the method according to any one of claims 9 to 12.

14. 14. An electrochemical cell comprising the solid electrolyte of claim 13.

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