Sulfidic solid electrolyte and its precursor

Abstract

To provide a precursor for producing a homogeneous solid electrolyte having excellent electrical properties such as high ionic conductivity and electrochemical stability, a method for producing the precursor, a method for producing a solid electrolyte, a solid electrolyte, and an electrochemical cell.SOLUTION: A solid / gas phase method comprising reacting a solid electrolyte precursor represented by the formula Li(2a+b)SaXb [wherein X is independently selected from group 17 elements, 2≤a≤3, and 0<b≤2] with at least partially gaseous Y-containing components, is used to provide an improved solid electrolyte having high purity and homogeneity, represented by the formula Li(2c+d-n)Yn+ScXd [wherein X is independently selected from group 17 elements, Y is independently selected from P, As, Ge, Si, B, Sn, Ga, Al, and Sb, 4≤n≤5, 4≤c≤6, and 0<d≤2].SELECTED DRAWING: None

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, the formula Li (2a + b) S a X b [In the formula, X is independently selected from Group 17 elements; 2≦a≦3, and 0 <b≦2である] The solid / gas phase method comprises reacting a solid electrolyte precursor having the formula Li with a Y-containing component in at least a gaseous state. (2c + d - n) Y n+ S c X d [In the formula, Y is independently selected from P, As, Ge, Si, B, Sn, Ga, Al, and Sb; 4≦n≦5, 4≦c≦6, and 0 <d≦2である] It has been found that this allows for the provision of improved solid electrolytes having high purity and homogeneity, as represented by

[0013] In a first aspect, the present invention provides a compound of formula (I): Li (2a + b) S a X b (I) [In the formula, X is independently selected from Group 17 elements; 2≦a≦3, and 0 <b≦2である] The present invention relates to a solid electrolyte precursor represented by

[0014] 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 ) b is.

[0015] The stoichiometric ratio of X can be in the range of 0.8≦b≦1.2, more preferably b=1. The stoichiometric ratio of S can be in the range of 2.4≦a≦2.6, more preferably a=2.5. In particular, the solid electrolyte precursor is Li6S 2.5 Cl, Li6S 2.5 Br or Li6S 2.5I.

[0016] The solid electrolyte precursor has at least a partially ordered atomic arrangement, and is preferably in a semi-crystalline or crystalline state, particularly in a crystalline state. The atomic arrangement of the precursor can be determined by conventional means known in the art, such as X-ray diffraction (XRD). In a preferred embodiment, the solid electrolyte precursor 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.

[0017] The solid electrolyte precursor according to the present invention has improved product homogeneity and purity, e.g., is substantially free of unreacted starting materials and / or secondary phases of different composition, preferably free of unreacted starting materials and secondary phases of different composition.

[0018] 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 allowing mixed electronic and ionic conduction.

[0019] 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 first reactant gas and at least one second reactant gas with the lithium salt of step (i) at an elevated temperature; and (iii) optionally discharging the product obtained in step (ii); wherein one of the first reactant gas and the second reactant gas is a sulfur-containing gas, and the other reactant gas is an X-containing gas. The present invention relates to the method.

[0020] 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 less than 1% by weight, more preferably 0.01-0.1% by weight.

[0021] Optionally, step (i) is preceded by a step of pre-drying the lithium salt at elevated temperature, for example at least 80°C, preferably from 90 to 250°C, optionally under reduced pressure, i.e. below atmospheric pressure (<1013 mbar), for example below 500 mbar, for example from 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 less than 1% by weight, more preferably less than 0.1% by weight.

[0022] 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% by volume, preferably 0.01 to 5% by volume, more preferably less than 2% by volume.

[0023] In step (ii), the lithium salt of step (i) is contacted with at least one first reactant gas and at least one second reactant gas at an elevated temperature, for example above 80°C, preferably 90-250°C. Step (ii) can be carried out under a dry air or inert gas atmosphere, for example N2, He or Ar, where the inert gas or dry air is preferably substantially water-free, i.e., has less than 10% RH by volume, preferably 0.01-5% by volume, more preferably less than 2% by volume. When both steps (i) and (ii) are carried out under an inert gas or dry air atmosphere, the gases can be (essentially) the same.

[0024] In one embodiment, the at least one first reactant gas is a hydrogen halide, such as HCl, HBr, HI, or a mixture thereof, preferably HCl or HBr. The at least one second reactant gas may be a sulfur source selected from HS, S, CS, mercaptans, or a mixture thereof, preferably HS.

[0025] In another embodiment, the at least one first reactant gas may be a sulfur source selected from HS, S, CS, mercaptans, or mixtures thereof, preferably HS. The at least one second reactant gas may be a hydrogen halide, such as HCl, HBr, HI, or mixtures thereof, preferably HCl or HBr.

[0026] In particular, the at least one first reaction gas and / or the at least one second reaction gas are substantially water-free, i.e., they independently have less than 10% RH by volume, preferably 0.01-5% by volume, more preferably less than 2% by volume.

[0027] The first and second reactant gases can be supplied sequentially or simultaneously in step (ii). In a preferred embodiment, the first and second reactant gases are supplied simultaneously, where they are contacted, preferably mixed, by conventional techniques known in the art prior to step (ii).

[0028] The molar ratio of S in the S-containing reaction gas to X in the X-containing reaction gas is, for example, 10:1 to 1:1, preferably 3:1 to 1.5:1, and more preferably 2.6:1 to 2.4:1. The molar ratio of S in the S-containing component and X in the X-containing component in the reaction gas to Li in the lithium salt prepared in step (i) is, for example, 10:1 to 1:1, preferably 10:1 to 5:1, and more preferably 7:1 to 5:1.

[0029] The at least one first 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 essentially water-free, i.e., have an RH content of less than 10% by volume, preferably 0.01 to 5% by volume, more preferably less than 2% by volume. Preferably, the carrier gas corresponds to the inert gas, preferably dry air or water-free N2, used in step (i) and / or step (ii), as appropriate.

[0030] The at least one second reaction gas may also comprise a carrier gas. Suitable carrier gases are as described herein and are preferably dry air or anhydrous N2, and in particular are substantially anhydrous, i.e., have less than 10% by volume RH, preferably 0.01-5% by volume, more preferably less than 2% by volume. In a preferred embodiment, the carrier gas of the second reaction gas corresponds, as appropriate, to the carrier gas of the first reaction gas and / or the inert gas applied in step (i) and / or step (ii), preferably dry air or anhydrous N2.

[0031] 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 / h, where the total gas flow rate includes the S-containing reaction gas, the X-containing reaction gas, and the 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 said water, for example, by gas flow through the reaction vessel.

[0032] 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.

[0033] To provide a suitable reaction atmosphere, such as an inert gas or dry air, during step (i) and / or step (ii), 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, an inert gas, a 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.

[0034] In one embodiment, the product obtained in step (ii) is discharged from the reaction vessel. In another embodiment, the method according to the present invention further comprises the step of adding at least one doping agent, such as an anionic or cationic doping agent, to the product obtained in step (ii). Cationic doping agents can include Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, Se, O, Te, Mg, Na, Ca, Sb, B, Ga, or mixtures thereof in their respective oxidation states. Anionic doping agents can include 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. The step of adding at least one doping agent may further comprise mixing the product obtained in step (ii) with the at least one doping agent by comminution means, for example, by ball milling or stirring as known in the art.

[0035] 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.

[0036] Therefore, in a further aspect, the present invention relates to the use of a solid electrolyte precursor according to the invention for producing a solid electrolyte, in particular said solid electrolyte having the following formula (II): Li (2c + d - n) Y n+ S c X d (II) [Wherein, X is independently selected from Group 17 elements, preferably Cl, Br and I, Y is independently selected from P, As, Ge, Si, B, Sn, Ga, Al and Sb, and is preferably P, 4 ≦ n ≦ 5, 4 ≦ c ≦ 6, preferably 4.5 ≦ c ≦ 5.5, and 0 < d ≦ 2, preferably 0.8 ≦ d ≦ 1.2.] It is represented by

[0037] Y n+ is preferably P 5+ , As 5+ , Ge 4+ , Si 4+ , B[[ID=​​​​​​​​​​​​​​​​​​​​​​​​​

[0040] Step (a) may 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 0.01 to 5% by volume, more preferably less than 2% by volume.

[0041] In step (b), the solid electrolyte precursor of step (a) is contacted with a Y-containing component at elevated temperature. The Y-containing component can be selected from P2S5, As2S5, GeS2, SiS2, B2S3, SnS, Ga2S3, Al2S3, Sb2S5, or mixtures thereof, and is preferably P2S5. Preferably, the Y-containing component is substantially water-free, i.e., has an RH of less than 10 wt.%, preferably 0.01-5 wt.%, more preferably less than 2 wt.%.

[0042] The temperature maintained in step (b) is sufficient to at least partially bring the Y-containing component into a gas phase, for example at least 285° C., preferably 288-900° C. In a preferred embodiment, the Y-containing component is heated outside the reaction vessel, for example to a temperature of at least 285° C., preferably 288-900° C., such that step (b) comprises contacting the Y-containing gas with the solid electrolyte precursor of step (a) at an elevated temperature. The molar ratio of Y in the Y-containing component to the solid electrolyte precursor provided in step (a) may be 0.2:1 to 2:1, preferably 0.5:1 to 1:1.

[0043] Step (b) can be carried out under a dry air or inert gas atmosphere, such as N2, He or Ar, where the dry air or inert gas is preferably water-free, i.e., has less than 10% RH by volume, preferably 0.01-5% by volume, more preferably less than 2% by volume. When both steps (a) and (b) are carried out under an inert gas or dry air, the gases can be (essentially) the same.

[0044] 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 anhydrous, i.e., have an RH content of less than 10% by volume, preferably 0.01-5% by volume, more preferably less than 2% by volume. Preferably, the carrier gas corresponds to the inert gas applied in step (a) and / or step (b), as appropriate, and is preferably dry air or anhydrous N2.

[0045] Step (b) is performed with 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 / h, e.g. 20m 3 / h, where the total gas flow rate includes the Y-containing reaction gas and, where appropriate, a carrier gas. The total gas flow rate may depend, inter alia, on the amount of solid electrolyte precursor prepared in step (a), the type of solid electrolyte to be obtained, and the reaction temperature. The duration of step (b) may be up to 24 hours, for example, from 15 minutes to 15 hours, depending on the individual reaction conditions.

[0046] To provide a suitable reaction atmosphere, such as an inert gas or dry air, during step (a) and / or step (b), the reaction vessel can be sealed and isolated from the surroundings, while at least one gas inlet and at least one gas outlet can allow for controlled introduction and removal of gases, such as dry air, an inert gas, a Y-containing reaction gas, and / or a carrier gas, into and from the vessel, respectively. The reaction vessel can be, for example, a heatable fluidized bed reactor known in the art.

[0047] In one embodiment, the product obtained in step (b) is discharged from the reaction vessel. The present invention also encompasses the above-described method for producing 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 include Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, Se, O, Te, Mg, Na, Ca, Sb, B, Ga, or a mixture thereof, in each oxidation state. The anionic doping agent may include O. 2- , S 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.

[0048] 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.

[0049] 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 a grinding means, such as a ball mill, 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.

[0050] In a further aspect, the present invention relates to solid electrolytes obtained by the methods described herein. In contrast to solid electrolytes obtained by methods known in the art, such as solid-based or solvent-based methods, solid electrolytes obtained by the methods according to the present invention have improved product homogeneity and purity, and are free of unreacted starting materials and secondary phases of different composition. By this means, solid electrolytes with improved electrical properties, such as improved ionic conductivity and electrochemical stability, are obtained. Preferably, the solid electrolytes obtained by the methods described herein have an ionic conductivity of 0.01 to 500 mS / cm, preferably 1 to 100 mS / cm, at 20°C.

[0051] 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.

[0052] In a preferred embodiment, the solid electrolyte 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.

[0053] 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.

[0054] In a preferred embodiment, the solid electrolyte according to the present invention has a 2θ angle [°] of: 17.5, 18.0, 34.9, 44.8, 50.2, and / or 53.1, more particularly 17.5, 18.0, 34.9, 44.8, 50.2 and 53.1.α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0055] In another preferred embodiment, the solid electrolyte according to the present invention has a 2θ angle [°] of: 17.5, 18.0, 32.5, 44.8, 46.7, and / or 53.1, more particularly 17.5, 18.0, 32.5, 44.8, 46.7 and 53.1. α It has virtually no reflections in powder X-ray diffraction using a line filter.

[0056] 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 strongest product reflection recorded for the particular solid electrolyte.

[0057] In a still further aspect, the present invention provides a compound of formula (II): Li (2c + d - n) Y n+ S c X d (II) [In the formula, X is independently selected from Group 17 elements, preferably Cl, Br and I; Y is independently selected from P, As, Ge, Si, B, Sn, Ga, Al, and Sb; 4≦n≦5, 4≦c≦6, and 0 <d≦2である] CuK at 2θ angles [°]: 17.5, 18.0, 32.5, 34.9, 44.8, 46.7, 50.2 and / or 53.1 α The present invention relates to a solid electrolyte having substantially no reflections in powder X-ray diffraction using X-rays.

[0058] In a preferred embodiment, the solid electrolyte according to the present invention is CuK at 2θ angles [°]: 17.5, 18.0, 34.9, 44.8, 50.2, and 53.1. α It has substantially no reflections in powder X-ray diffraction using X-rays.

[0059] In another embodiment, the solid electrolyte according to the present invention has a structure of CuK at 2θ angles [°]: 17.5, 18.0, 32.5, 44.8, 46.7, and 53.1. α Using wire, CuK α It has virtually no reflections in filtered powder X-ray diffraction.

[0060] 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 strongest product reflection recorded for the particular solid electrolyte.

[0061] In a preferred embodiment, the solid electrolyte according to formula (II) has a CuK α In a preferred embodiment, the solid electrolyte has characteristic reflections in powder X-ray diffraction using CuK at 2θ angles [°]: 25.5, 30.0, and 31.4. α In another embodiment, the solid electrolyte contains characteristic reflections in powder X-ray diffraction using CuK at 2θ angles [°]: 25.2, 29.6, and 31.0. α These include characteristic reflections in powder X-ray diffraction using X-rays.

[0062] A "characteristic reflection" in the sense of the present invention is a reflection that has an intensity of at least 40%, preferably at least 50%, more preferably at least 60% of the most intense reflection recorded for a particular solid electrolyte.

[0063] X is independently selected from Group 17 elements, preferably F, 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, for example, X=(Cl 0.5 Br 0.5 ) d is.

[0064] Y n+ is preferably P 5+ , As 5+ , Ge 4+ , Si 4+ , B 3+ , Sn 4+ , Ga 3+ , Al 3+ and Sb 5+ In one embodiment, Y n+ HA P 5+ or As 5+ or Ge 4+ or Si 4+ or B 3+ or Sn 4+ or Ga 3+ or Al 3+ or Sb 5+ , preferably P 5+ In another embodiment, Y n+ HA P 5+ , As 5+ , Ge 4+ , Si 4+ , B 3+ , Sn 4+ , Ga 3+ , Al 3+ and Sb 5+ a mixture of at least two of the above, for example P 5+ and As 5+ Mixtures with, or P 5+ and Sb 5+and the ratio of element Y1 to element Y2 is 0.01:0.99 to 0.99:0.01, preferably 0.1:0.9 to 0.9:0.1, and more preferably 0.3:0.7 to 0.7:0.3.

[0065] In a preferred embodiment, the stoichiometry of X is 0.5≦d≦1.5, more preferably 0.8≦d≦1.2. In a preferred embodiment, the stoichiometry of S is 4.5≦c≦5.5, more preferably 4.8≦c≦5.2.

[0066] In a preferred embodiment, the stoichiometry of X is 0.5≦d≦1.5, preferably 0.8≦d≦1.2, and the stoichiometry of S is 4.5≦c≦5.5, preferably 4.8≦c≦5.2. In particular, the solid electrolyte is Li6PS5Cl, Li6PS5Br or Li6PS5I.

[0067] The solid electrolyte is preferably in a crystalline state, e.g., has an argyrodite-like crystal structure (orthorhombic pyramidal, space group F-43m). The atomic arrangement of the solid electrolyte can be determined by conventional means known in the art, e.g., X-ray diffraction (XRD).

[0068] The solid electrolyte may further comprise at least one dopant. A dopant in the sense of the present invention is an auxiliary element introduced into the solid electrolyte (crystalline) structure to change its electrical properties. The type of dopant as well as its concentration significantly influences the resulting material properties. Suitable cationic dopants are, for example, Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, Se, O, Te, Mg, Na, Ca, Sb, B, Ga, or mixtures thereof in their respective oxidation states. Anionic doping agents are O 2- , S 2- , Te 2-Dopants selected from B, As, Se, and Ni, in their respective oxidation states, are particularly useful for enhancing ionic conductivity or enabling mixed electronic and ionic conduction. The dopant may be present in an amount of less than 10 wt. %, preferably 0.01 to 9.0 wt. %, more preferably 0.10 to 5.0 wt. %, based on the total weight of the solid electrolyte.

[0069] In contrast to conventional solid electrolytes, the solid electrolytes of the present invention have improved product homogeneity and purity, e.g., are free of unreacted starting materials and compositionally distinct secondary phases. In preferred embodiments, the solid electrolyte is in the form of a pure phase. Suitable means for determining product homogeneity and purity, as well as the presence of a pure phase, are described herein.

[0070] By this means, a solid electrolyte having improved electrical properties, such as high ionic conductivity and electrochemical stability, can be obtained. Preferably, the solid electrolyte has an ionic conductivity of 0.01 to 500 mS / cm, preferably 1 to 100 mS / cm at 20°C.

[0071] In a further aspect, the present invention relates to the use of a solid electrolyte precursor according to the invention in an electrochemical cell. In a still further aspect, the present invention relates to the use of a solid electrolyte precursor according to the invention in a fuel cell. In a still further aspect, the present invention relates to the use of a solid electrolyte precursor according to the invention in a battery. In a still further aspect, the present invention relates to the use of a solid electrolyte precursor according to the invention in a sensor. In a still further aspect, the present invention relates to the use of a solid electrolyte precursor according to the invention in a supercapacitor. Furthermore, the present invention relates to an electrochemical cell comprising a solid electrolyte according to the present invention.

[0072] The present invention is further explained in more detail but is not limited to the following figures and examples. [Brief explanation of the drawings]

[0073] [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]

[0074] 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 HCl and HS in a molar ratio of 1:2.5, as well as nitrogen as a carrier gas at a content of 95% by volume relative to the total amount of gas, with a total gas flow rate of 18 m 3 / h for 1 hour at 150° C. to give a solid electrolyte precursor.

[0075] Next, the solid electrolyte precursor was mixed with gaseous P2S5 at 288°C with a total gas flow rate of 18 m 3 / h (containing nitrogen as a carrier gas at a content of 95% by volume relative to the total amount of gas) for 1 hour, where the molar ratio of P2S5 to the solid electrolyte precursor was 0.5:1.

[0076] 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 by 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 it into a 13 mm diameter pressure sample cell equipped with stainless steel electrodes. The pressure applied during the measurements was p = 3 t. Powder X-ray diffraction analysis was performed on a Bruker D2 PHASER diffractometer using CuK α The scan was performed over the 2θ range of 5 to 90° with a step width of 0.020°.

[0077] Each powder pattern showed 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 (see Figure 1).

[0078] The present invention encompasses the following: 1. The following formula (I): Li (2a + b) S a X b (I) [In the formula, X is independently selected from Group 17 elements; 2≦a≦3, and 0 <b≦2である] A solid electrolyte precursor represented by

[0079] 2. The precursor according to item 1, wherein X is independently selected from the group consisting of Cl, Br and I.

[0080] 3. The precursor according to item 1 or 2, wherein 0.8≦b≦1.2.

[0081] 4. A precursor according to any one of items 1 to 3, wherein 2.4≦a≦2.6.

[0082] 5. Li6S 2.5 Cl, Li6S 2.5 Br and Li6S 2.5 5. The precursor according to any one of items 1 to 4, selected from I.

[0083] 6. The precursor according to any one of items 1 to 5, further comprising at least one dopant.

[0084] 7. The precursor according to item 6, wherein the dopant is selected from Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, Se, O, Te, Mg, Na, Ca, Sb, B, Ga or mixtures thereof in their respective oxidation states.

[0085] 8. The precursor according to item 6 or 7, 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.

[0086] 9. A precursor according to any one of items 1 to 8, which is in a crystalline state, preferably in the form of a pure phase.

[0087] 10. A method for producing a solid electrolyte precursor according to any one of items 1 to 9, comprising: (i) providing a lithium salt in a reaction vessel; (ii) contacting at least one first reactant gas and at least one second reactant gas with the lithium salt of step (i) at an elevated temperature; and (iii) optionally discharging the product obtained in step (ii); wherein one of the first reactant gas and the second reactant gas is a sulfur-containing gas, and the other reactant gas is an X-containing gas.

[0088] 11. The method according to item 10, wherein the lithium salt has a water content of 0 to 50% by mass, preferably 0 to 10% by mass.

[0089] 12. The method according to item 10 or 11, 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.

[0090] 13. The method according to any one of items 10 to 12, wherein the lithium salt in step (i) is LiOH, Li2CO3, Li2SO4, Li2O, Li2O2, or a mixture thereof.

[0091] 14. The method according to any one of items 10 to 13, wherein step (i) and / or step (ii) is carried out under dry air or an inert gas atmosphere, such as N2, He or Ar.

[0092] 15. The method according to item 14, wherein the inert gas or dry air is substantially free of water.

[0093] 16. The method according to any one of items 10 to 15, wherein step (ii) is carried out at a temperature above 80°C, preferably from 90 to 250°C.

[0094] 17. The method according to any one of items 10 to 16, wherein the at least one first reactant gas is a hydrogen halide, such as HCl, HBr, HI or a mixture thereof, and preferably the at least one second reactant gas is a sulfur source selected from H2S, S8, CS2, a mercaptan or a mixture thereof.

[0095] 18. The method according to any one of items 10 to 17, wherein the at least one reactant gas is a sulfur source selected from H2S, S8, CS2, mercaptans or mixtures thereof, and preferably the at least one second reactant gas is a hydrogen halide, such as HCl, HBr, HI or mixtures thereof.

[0096] 19. The method according to any one of items 10 to 18, wherein in step (ii), the first reactant gas and the second reactant gas are supplied sequentially or simultaneously.

[0097] 20. The method according to any one of items 10 to 19, wherein the at least one first reactant gas and the at least one second reactant gas are contacted before step (ii).

[0098] 21. The method of any one of items 10 to 20, wherein the at least one first reactant gas and the at least one second reactant gas are substantially water-free.

[0099] 22. The method according to any one of items 10 to 21, wherein the molar ratio of S in the S-containing reaction gas to X in the X-containing reaction gas is, for example, 10:1 to 1:1, preferably 3:1 to 1.5:1, and more preferably 2.6:1 to 2.4:1.

[0100] 23. The method of any one of items 10 to 22, wherein the at least one first reactive gas further comprises a carrier gas.

[0101] 24. The method of any one of items 10 to 23, wherein the at least one second reactive gas further comprises a carrier gas.

[0102] 25. Step (ii) 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 / h, and even more preferably about 20 m 3 25. The method according to any one of items 10 to 24, wherein the method is carried out for 1 hour at 25°C / h.

[0103] 26. The method according to any one of items 10 to 25, further comprising a step of adding to the product obtained in step (ii) at least one doping agent, for example a doping agent comprising 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 as dopants.

[0104] 27. The method according to item 26, wherein the at least one doping agent is an anionic or cationic doping agent, in particular provided in the form of a salt.

[0105] 28. Use of a solid electrolyte precursor according to any one of items 1 to 9 for producing a solid electrolyte.

[0106] 29. The solid electrolyte has the following formula (II): Li (2c + d - n) Y n+ S c X d (II) [In the formula, X is independently selected from Group 17 elements, preferably Cl, Br and I; Y is independently selected from P, As, Ge, Si, B, Sn, Ga, Al, and Sb; 4≦n≦5, 4≦c≦6, and 0 <d≦2である] Item 29. The use according to item 28, represented by

[0107] 30. A method for producing a solid electrolyte, comprising: (a) providing a solid electrolyte precursor according to any one of items 1 to 9 in a reaction vessel; (b) contacting a Y-containing component with the solid electrolyte precursor of step (a); and (c) optionally discharging the product obtained in step (b); wherein step (b) is carried out at an elevated temperature, wherein Y is independently selected from P, As, Ge, Si, B, Sn, Ga, Al, and Sb, and wherein the Y-containing component is at least partially present in the vapor phase in step (b).

[0108] 31. The method according to item 30, 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.

[0109] 32. The method according to item 31, wherein the inert gas or dry air is substantially free of water.

[0110] 33. The method according to any one of items 30 to 32, wherein step (b) is carried out at a temperature higher than 285°C, preferably 288 to 900°C.

[0111] 34. The method of any one of items 30 to 33, wherein the Y-containing component is selected from P2S5, As2S5, GeS2, SiS2, B2S3, SnS, Ga2S3, Al2S3, Sb2S5, or mixtures thereof.

[0112] 35. The method according to any one of items 30 to 34, wherein in step (b), the molar ratio of Y in the Y-containing component to the solid electrolyte precursor prepared in step (a) is 0.2:1 to 2:1, preferably 0.5:1 to 1:1.

[0113] 36. The method of any one of items 30 to 35, wherein the Y-containing component is substantially water-free.

[0114] 37. The method of any one of items 30 to 36, wherein the Y-containing component further comprises a carrier gas.

[0115] 38. Step (b) 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 / h, and even more preferably about 20 m 3 38. The method according to any one of items 30 to 37, wherein the method is carried out at 1000 kJ / h.

[0116] 39. The method according to any one of items 30 to 38, further comprising the step of adding at least one doping agent, such as a cationic or anionic doping agent, to the product obtained in step (b).

[0117] 40. The at least one cationic dopant comprises 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, and / or the anionic dopant comprises O 2- , S 2- , Se 2- or Te 2- Item 39. The method according to Item 39, comprising:

[0118] 41. A solid electrolyte obtained by the method according to any one of items 30 to 40.

[0119] 42. The compound of formula (II): Li (2c + d - n) Y n+ S c X d (II) [In the formula, X is independently selected from Group 17 elements; Y is independently selected from P, As, Ge, Si, B, Sn, Ga, Al, and Sb; 4≦n≦5, 4≦c≦6, and 0 <d≦2である] CuK at 2θ angles [°]: 17.5, 18.0, 32.5, 34.9, 44.8, 46.7, 50.2 and / or 53.1 α A solid electrolyte having substantially no reflections in powder X-ray diffraction using X-rays.

[0120] 43. 2θ angles [°]: 17.5, 18.0, 32.5, 34.9, 44.8, 46.7, 50.2, and 53.1 for CuK α Item 43. The solid electrolyte according to item 42, having substantially no reflections in powder X-ray diffraction using X-rays.

[0121] 44. CuK at 2θ angles [°]: 25.2, 25.5, 29.6, 30.0, 31.0 and / or 31.4 α 44. The solid electrolyte according to item 42 or 43, having characteristic reflections in powder X-ray diffraction using X-rays.

[0122] 45. The solid electrolyte according to any one of items 42 to 44, further comprising at least one dopant.

[0123] 46. ​​The solid electrolyte according to item 45, wherein the dopant is selected from Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, Se, O, Te, Mg, Na, Ca, Sb, B, Ga, or mixtures thereof, in their respective oxidation states.

[0124] 47. The solid electrolyte according to item 45 or 46, 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, based on the total weight of the solid electrolyte.

[0125] 48. A solid electrolyte according to any one of items 42 to 47, having an ionic conductivity at 20°C of 0.01 to 500 mS / cm, preferably 1 to 100 mS / cm.

[0126] 49. The solid electrolyte according to any one of items 42 to 48, wherein X is independently selected from Cl, Br, and I.

[0127] 50. A solid electrolyte according to any one of items 42 to 49, wherein 0.8≦d≦1.2.

[0128] 51. A solid electrolyte according to any one of items 42 to 50, wherein 4.5≦c≦5.5.

[0129] 52. Y n+ P 5+ , As 5+ , Ge 4+ , Si 4+ , B 3+ , Sn 4+ , Ga 3+ , Al 3+ and Sb 5+ 52. The solid electrolyte according to any one of items 42 to 51, independently selected from:

[0130] 53. Y n+ P 5+ 53. The solid electrolyte according to any one of items 42 to 52, wherein

[0131] 54. A solid electrolyte according to any one of items 42 to 53, selected from Li6PS5Cl, Li6PS5Br and Li6PS5I.

[0132] 55. An electrochemical cell comprising a solid electrolyte according to any one of items 42 to 53.

[0133] 56. Use of a solid electrolyte according to any one of items 42 to 53 in an electrochemical cell or capacitor, a fuel cell, a battery or a sensor.

Claims

1. Formula (I): Li (2a + b) S a X b (I) [In the formula, X is independently selected from Group 17 elements, preferably Cl, Br and I; 2≦a≦3, preferably 2.4≦a≦2.6, and 0<b≦2, preferably 0.8≦b≦1.2] A solid electrolyte precursor represented by

2. Li 6 S 2.5 Cl, Li 6 S 2.5 Br and Li 6 S 2.5 2. The precursor of claim 1, wherein the precursor is selected from:

3. 3. The precursor according to claim 1 or 2, further comprising at least one dopant, for example at least one dopant selected from Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, Se, O, Te, Mg, Na, Ca, Sb, B, Ga or mixtures thereof.

4. A method for producing a solid electrolyte precursor according to any one of claims 1 to 3, comprising: (i) providing a lithium salt in a reaction vessel; (ii) contacting at least one first reactant gas and at least one second reactant gas with the lithium salt of step (i) at an elevated temperature, for example above 80°C, preferably 90-250°C; and (iii) optionally discharging the product obtained in step (ii). wherein one of the first reactant gas and the second reactant gas is a sulfur-containing gas, and the other reactant gas is an X-containing gas.

5. The lithium salt in step (i) is LiOH, Li 2 CO 3 , Li 2 SO 4 , Li 2 O, Li 2 O 2 5. The method of claim 4, wherein the hydroxybenzoate is a hydroxybenzoate, ...

6. The at least one first reactant gas is a hydrogen halide, such as HCl, HBr, HI, or a mixture thereof, and preferably the at least one second reactant gas is H 2 S, S 8 , C.S. 2 a sulfur source selected from the group consisting of mercaptans, mercaptans, and mixtures thereof; The at least one first reactant gas is H 2 S, S 8 , C.S. 2 , mercaptans, or mixtures thereof, and preferably, the at least one second reactant gas is a hydrogen halide, such as HCl, HBr, HI, or mixtures thereof; The method according to claim 4 or 5.

7. 7. The method according to claim 4, wherein the molar ratio of S in the S-containing reaction gas to X in the X-containing reaction gas is from 10:1 to 1:1, preferably from 3:1 to 1.5:1, more preferably from 2.6:1 to 2.4:

1.

8. 4. Use of a solid electrolyte precursor according to any one of claims 1 to 3 for producing a solid electrolyte.

9. A method for producing a solid electrolyte, comprising: (a) providing a solid electrolyte precursor according to any one of claims 1 to 3 in a reaction vessel; (b) contacting a Y-containing component with the solid electrolyte precursor of step (a); and (c) optionally discharging the product obtained in step (b). Including, Step (b) is carried out at elevated temperatures, for example above 285°C, preferably 288-900°C; Y is independently selected from P, As, Ge, Si, B, Sn, Ga, Al, and Sb; and In step (b), the Y-containing component is at least partially in the gas phase. The method.

10. The Y-containing component is P 2 S 5 , As 2 S 5 , GeS 2 , SiS 2 , B 2 S 3 , SnS, Ga 2 S 3 , Al 2 S 3 , Sb 2 S 5 10. The method of claim 9, wherein the hydroxybenzoate is selected from the group consisting of:

11. 11. The method according to claim 9 or 10, wherein in step (b), the molar ratio of Y in the Y-containing component to the solid electrolyte precursor provided in step (a) is from 0.2:1 to 2:1, preferably from 0.5:1 to 1:

1.

12. A solid electrolyte obtainable by the method according to any one of claims 9 to 11.

13. Formula (II): Li (2c + d - n) Y n+ S c X d (II) [In the formula, X is independently selected from Group 17 elements, preferably Cl, Br and I; Y is independently selected from P, As, Ge, Si, B, Sn, Ga, Al, and Sb; 4≦n≦5, 4≦c≦6, and 0<d≦2] and CuK at 2θ angles [°]: 17.5, 18.0, 32.5, 34.9, 44.8, 46.7, 50.2 and / or 53.1 α A solid electrolyte having substantially no reflections in powder X-ray diffraction using X-rays.

14. 14. The solid electrolyte of claim 13, further comprising at least one dopant, such as Mn, Ge, Sn, V, Ni, Cr, Si, Al, As, Se, O, Te, Mg, Na, Ca, Sb, B, Ga or mixtures thereof.

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

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