SULFIDE SOLID ELECTROLYTE MATERIAL, GAS-PHASE SYNTHESIS METHOD FOR MATERIALS THEREOF AND APPLICATION THEREOF

Abstract

A sulfide solid electrolyte material, a gas-phase synthesis method for materials thereof and an application thereof are disclosed. The gas-phase synthesis method comprises: weighing a Li source and an M source according to a defined ratio, the M source being an oxide or sulfide of at least one of group 4, 5, 6, 13, 14 and 15 elements from the third period to the sixth period in the periodic table of elements; mixing and placing the mixed raw materials into a furnace; adding an S source into a sulfur source gas generation device; using a carrier gas, and performing gas washing on the furnace for a certain duration at a set ventilation rate; heating the furnace to 200-800 C. at a set heating rate in an environment in which the gas containing the S source is introduced at the set ventilation rate, keeping warm for a set duration, and then cooling to room temperature; and removing a sulfide solid electrolyte from the furnace.

Claims

1. A method of gas phase synthesis for a sulfide solid-electrolyte material, comprising: weighing a Li source and an M source, as raw materials, according to a desired ratio, then mixing the Li source and the M source, and putting the mixed raw materials into a heating furnace, wherein the Li source comprises at least one of Li.sub.2CO.sub.3, Li.sub.2O, Li.sub.2S, LiOH, LiCl, lithium acetate, lithium sulfate, lithium nitrate, or lithium metal, and the M source comprises at least one of an elementary substance of an M element, an oxide of the M element, and a sulfide of the M element, with the M element being at least one element selected from elements of Groups 4, 5, 6, 13, 14, and 15 in the periodic table of the elements from Period 3 to Period 6; adding an S source to a sulfur-source gas generation device, wherein the S source comprises one or more of an S-containing gas, a sulfur-containing organic compound, a polysulfide, a sulfate, or a metal sulfide; connecting a carrier gas generation device, a gas flow meter, the sulfur-source gas generation device, the heating furnace, and a tail gas treatment device in sequence to form a gas phase synthesis device; carrying a gas containing the S source by a carrier gas, and performing gas washing on the heating furnace for a certain period of time at a set ventilation rate; after the gas washing is completed, heating the heating furnace to 200 C.-800 C. at a set heating rate in an environment in which the gas containing the S source is introduced at the set ventilation rate, holding the temperature for a set period of time, and then cooling to room temperature; and after the cooling, removing a sulfide solid electrolyte from the heating furnace.

2. The method of claim 1 wherein: the M element comprises at least one of Sn, Sb, As, P, Si, Ge, and Bi; the M source comprises at least one of an Sn source, an Sb source, an As source, and a P source; the Sn source comprises at least one of elemental Sn, SnO.sub.2, SnS.sub.2, SnCl.sub.4, and their hydrates; the Sb source comprises at least one of elemental Sb, Sb.sub.2O.sub.5, Sb.sub.2O.sub.3, Sb.sub.2S.sub.5, and Sb.sub.2S.sub.3; the As source comprises at least one of elemental As, As.sub.2O.sub.5, As.sub.2O.sub.3, As.sub.2S.sub.5, and As.sub.2S.sub.3; the P source comprises at least one of elemental P, P.sub.2S.sub.3, P.sub.2S.sub.5, and P.sub.2O.sub.5; an Si source comprises at least one of elemental Si, SiO, SiO.sub.2, SiS.sub.2, SiCl.sub.4, and hydrates thereof; a Ge source comprises at least one of elemental Ge, GeO.sub.2, GeS, GeS.sub.2, GeCl.sub.4, and hydrates thereof; a Bi source comprises at least one of elemental Bi, Bi.sub.2O.sub.3, Bi.sub.2S.sub.3, and Bi(OH).sub.3; the S-containing gas comprises at least one of hydrogen sulfide, sulfur dioxide, sulfur trioxide, sulfur-containing natural gas, sulfur vapor, and carbon disulfide vapor; the sulfur-containing organic compound comprises at least one of methyl mercaptan, methyl sulfide, dimethyl disulfide, thiophene, ethanethiol, ethyl sulfide, methyl ethyl sulfide, and thiourea; and the carrier gas comprises any one of N.sub.2, CO.sub.2, and an Ar gas.

3. The method of claim 1, wherein a method for the mixing comprises: mortar grinding or mechanical mixing; a time for the mortar grinding is in a range from 10 minutes to 120 minutes; and the mechanical mixing comprises performing mechanical mixing by using a roller mill, a ball mill, or a spray mill, for a mixing time in a range of 1 hour to 8 hours.

4. The method of claim 1, wherein: the certain period of time is in a range from 10 minutes to 120 minutes; the set period of time is in a range from 10 hours to 72 hours; the set heating rate is in a range from 1 C./min minute to 10 C./minute; the cooling is performed at a set cooling rate, or by natural cooling, with the set cooling rate being in a range from 1 C./minute to 10 C./minute; and the set ventilation rate is in a range from 1 ml/minute to 30 ml/minute.

5. A method for gas phase synthesis of a raw material for a sulfide solid-electrolyte material, the method comprising: weighing out an A source according to a desired amount, and then putting the A source into a heating furnace, the A source including at least one of an oxide of A, a hydroxide of A, a carbonate of A, and elemental A; adding an S source to a sulfur-source gas generation device, wherein the S source comprises one or more of an S-containing gas, a sulfur-containing organic compound, a polysulfide, a sulfate, or a metal sulfide; connecting a carrier gas generation device, a gas flow meter, the sulfur-source gas generation device, the heating furnace, and a tail gas treatment device in sequence to form a gas phase synthesis device; carrying a gas containing the S source by a carrier gas, and performing gas washing on the heating furnace for a certain period of time at a defined ventilation rate; after the gas washing is completed, heating the heating furnace to 200 C.-800 C. at a set heating rate in an environment in which the gas containing the S source is introduced at a set ventilation rate, holding the temperature for a set period of time, and then cooling to room temperature; and after the cooling, removing the raw material for the sulfide solid electrolyte, from the heating furnace, wherein the raw material has a chemical formula of A.sub.xS.sub.y, with A being any one of Li, Si, Ge, Sn, P, As, Sb, and Bi, 0<x2, and 0<y5.

6. The method of claim 5, wherein: the carrier gas comprises any one of N.sub.2, CO.sub.2, and an Ar gas; the S-containing gas comprises at least one of hydrogen sulfide, sulfur dioxide, sulfur trioxide, sulfur-containing natural gas, sulfur vapor, and carbon disulfide vapor; and the sulfur-containing organic compound comprises at least one of methyl mercaptan, methyl sulfide, dimethyl disulfide, thiophene, ethanethiol, ethyl sulfide, methyl ethyl sulfide, and thiourea.

7. The method of claim 5, wherein: the certain period of time is in a range from 10 minutes to 120 minutes; the set period of time is in a range from 10 hours to 72 hours; the set heating rate is in a range from 1 C./minute to 10 C./minute; the cooling is performed at a set cooling rate, or by natural cooling, with the defined cooling rate being in a range from 1 C./minute to 10 C./minute; and the set ventilation rate is in a range from 1 ml/minute to 30 ml/minute.

8. A sulfide solid-electrolyte material synthesized based on the of claim 1, wherein the sulfide solid-electrolyte material is used as an electrode material of a lithium battery.

9. A raw material for a sulfide solid-electrolyte material synthesized using the method of claim 5, wherein the raw material is used for synthesizing the sulfide solid-electrolyte material and the sulfide solid-electrolyte material is used as an electrode material of a lithium battery.

10. A lithium battery, comprising the sulfide solid-electrolyte material synthesized by the method for gas phase synthesis of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The technical solutions of the embodiments of the disclosure will be further described below in combination with the accompanying drawings and embodiments.

[0047] FIG. 1 shows a flowchart of a method for gas phase synthesis of a sulfide solid-electrolyte material according to an embodiment of the disclosure;

[0048] FIG. 2 shows a schematic structural diagram of a gas phase synthesis device according to an embodiment of the disclosure;

[0049] FIG. 3 shows a flowchart of a method for gas phase synthesis of a raw material for a sulfide solid-electrolyte material according to an embodiment of the disclosure;

[0050] FIG. 4 shows the comparison of X-ray diffraction (XRD) patterns of sulfide solid electrolytes Li.sub.4SnS.sub.4Li.sub.3.85Sn.sub.0.85Sb.sub.0.15S.sub.4, Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4, and Li.sub.4Sn.sub.0.9Si.sub.0.1S.sub.4, as LiSnS system crystals, prepared according to Examples 1, 2, 3 and 4 of the disclosure, with a PDF card 04-019-27403 of Li.sub.4SnS.sub.4 of an orthorhombic crystal system;

[0051] FIG. 5 shows the electrochemical impedance spectra (EIS) of sulfide solid electrolytes Li.sub.4SnS.sub.4Li.sub.3.85Sn.sub.0.85Sb.sub.0.15S.sub.4, Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4, and Li.sub.4Sn.sub.0.9Si.sub.0.1S.sub.4, as LiSnS system crystals, prepared according to Examples 1, 2, 3 and 4 of the disclosure;

[0052] FIG. 6 shows the Arrhenius curves and calculated activation energy of sulfide solid electrolytes Li.sub.4SnS.sub.4 and Li.sub.3.85Sn.sub.0.85Sb.sub.0.15S.sub.4, as LiSnS system crystals, prepared according to Examples 1 and 2 of the disclosure;

[0053] FIG. 7 shows an XRD pattern of a P-containing sulfide solid electrolyte Li.sub.10SnP.sub.2S.sub.12 prepared according to Example 5 of the disclosure;

[0054] FIG. 8 shows the Arrhenius curve and calculated activation energy of a P-containing sulfide solid electrolyte Li.sub.10SnP.sub.2S.sub.12 prepared according to Example 5 of the disclosure;

[0055] FIG. 9 shows the comparison of the XRD pattern of a raw material Li.sub.2S for a solid electrolyte material prepared according to Example 6 of the disclosure, with a PDF card 65-2981 of Li.sub.2S; and

[0056] FIG. 10 shows the initial cycle charging and discharging curves of an all-solid-state battery, assembled by using electrolyte Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4 prepared in Example 3 of the disclosure, according to Example 7 of the disclosure.

DETAILED DESCRIPTION

[0057] The present invention is further explained below by means of the accompanying drawings and specific embodiments. However, it should be understood that these embodiments are merely for the purpose of more detailed explanation, and should not be understood as limiting the present invention in any form, that is, these embodiments are not intended to limit the protection scope of the present invention.

[0058] The method of gas phase synthesis for a sulfide solid-electrolyte material of the disclosure includes the main method steps as shown in the flowchart of FIG. 1. The method will be introduced below in combination with the flowchart.

[0059] The method of gas phase synthesis for a sulfide solid-electrolyte material of the disclosure mainly includes the steps below.

[0060] In step 110, a lithium source (Li source) and an M source are weighed out as raw materials according to a desired ratio, then mixed, and put into a heating furnace.

[0061] The Li source includes at least one of Li.sub.2CO.sub.3, Li.sub.2O, Li.sub.2S, LiOH, LiCl, lithium acetate, lithium sulfate, lithium nitrate, or lithium metal.

[0062] The M source is at least one of an elementary substance of an M element, an oxide of the M element, and a sulfide of the M element, with the M element being at least one selected from elements of Groups 4, 5, 6, 13, 14, and 15 in the periodic table of the elements from Period 3 to Period 6. Preferably, the M element may be at least one of tin (Sn), antimony (Sb), arsenic (As), and phosphorus (P). That is, the M source is preferably at least one of the tin (Sn) source, the antimony (Sb) source, the arsenic (As) source, and the phosphorus (P) source. Further specifically, the tin (Sn) source includes: at least one of elemental Sn, SnO.sub.2, SnS.sub.2, SnCl.sub.4, and their hydrates; the antimony (Sb) source includes: at least one of elemental Sb, Sb.sub.2O.sub.5, Sb.sub.2O.sub.3, Sb.sub.2S.sub.5, and Sb.sub.2S.sub.3; the arsenic (As) source includes: at least one of elemental As, As.sub.2O.sub.5, As.sub.2O.sub.3, As.sub.2S.sub.5, and As.sub.2S.sub.3; the phosphorus (P) source includes: at least one of elemental P, P.sub.2S.sub.3, P.sub.2S.sub.5, and P.sub.2O.sub.5; a silicon (Si) source includes: at least one of elemental Si, SiO, SiO.sub.2, SiS.sub.2, SiCl.sub.4, and their hydrates; a germanium (Ge) source includes: at least one of elemental Ge, GeO.sub.2, GeS, GeS.sub.2, GeCl.sub.4, and their hydrates; and a bismuth (Bi) source includes: at least one of elemental Bi, Bi.sub.2O.sub.3, Bi.sub.2S.sub.3, and Bi(OH).sub.3.

[0063] A method for the mixing specifically includes mortar grinding or mechanical mixing. A time for the mortar grinding is within a range from 10 minutes to 120 minutes; and the mechanical mixing includes performing mechanical mixing by using a roller mill, a ball mill, or a spray mill, for a mixing time within a range of 1 hour to 8 hours.

[0064] In step 120, a sulfur (S) source is added to a sulfur-source gas generation device.

[0065] The S source includes one or more of an S-containing gas, a sulfur-containing organic compound, a polysulfide, a sulfate, or a metal sulfide. Further specifically, the S-containing gas includes: at least one of hydrogen sulfide, sulfur dioxide, sulfur trioxide, sulfur-containing natural gas, sulfur vapor, and carbon disulfide vapor.

[0066] The sulfur-containing organic compound includes: at least one of methyl mercaptan, methyl sulfide, dimethyl disulfide, thiophene, ethanethiol, ethyl sulfide, methyl ethyl sulfide, and thiourea.

[0067] In the S source, the polysulfide may be decomposed in an acidic solution to produce H.sub.2S and S; the sulfate may be thermochemically reduced with an organic matter to produce H.sub.2S; and the metal sulfide may react with hydrochloric acid or sulfuric acid to produce H.sub.2S. Consequently, the gas containing the S source that can be carried by the carrier gas is produced.

[0068] In step 130, a carrier gas generation device, a gas flow meter, the sulfur-source gas generation device, the heating furnace, and a tail gas treatment device are connected in sequence to form a gas phase synthesis device.

[0069] FIG. 2 shows a schematic structural diagram of a specific gas phase synthesis device.

[0070] In the figure, the carrier gas provided in the carrier gas generation device is high-purity nitrogen, and an output of the carrier gas generation device is connected to the flow meter to adjust the flow rate of the carrier gas, and then is led to the sulfur-source gas generation device. In this embodiment, the sulfur-source gas generation device is shown with carbon disulfide housed in a bottle.

[0071] A gas output of the sulfur-source gas generation device is connected to an input of the heating furnace. In step 110, the mixed raw materials of the lithium (Li) source and the M source are placed in the heating furnace in advance. Specifically, the heating furnace may be a tube heating furnace, in which case the mixed raw materials are first placed in a crucible and then delivered into a quartz tube of the tube heating furnace.

[0072] Finally, a tail gas from the heating furnace is lead to tail gas treatment.

[0073] In step 140, a gas containing the sulfur (S) source is carried by a carrier gas, and gas washing is performed on the heating furnace for a certain period of time at a set ventilation rate.

[0074] Specifically, in order to ensure a reaction environment is achieved within the heating furnace, it is necessary to introduce a gas of the S source or a carrier gas containing the S source in advance to perform gas washing on the heating furnace for a period of time. The time for gas washing is preferably within a range from 10 minutes to 120 minutes.

[0075] In a specific embodiment, any of nitrogen (N.sub.2), carbondioxide (CO.sub.2), argon (Ar) and other gases may be specifically used as the carrier gas. The set ventilation rate is specifically within a range from 1 ml/minute to 30 ml/minute.

[0076] In step 150, after the gas washing is completed, the heating furnace is heated to 200 C.-800 C. at a set heating rate in an environment in which the gas containing the S source is introduced at a set ventilation rate, the temperature is held for a range from 10 hours to 72 hours, and then the furnace is cooled to room temperature.

[0077] Specifically, ventilation conditions are the same as the steps of gas washing.

[0078] The set heating rate is within a range from 1 C./minute to 10 C./minute.

[0079] The cooling can be specifically performed at a set cooling rate within a range of 1 C./minute to 10 C./minute, or by natural cooling.

[0080] In this step, the gas containing the S source reacts with the mixed raw materials of the Li source and the M source. Taking an oxide of M as the M source and CS.sub.2 as the S source by way of example, the vulcanization reaction mechanism of CS.sub.2 is as follows: CS in CS.sub.2 is weaker than CO, such that CS is liable to be attacked by O in the oxide raw materials to further produce CO, in which case C leaves in the form of CO.sub.2 gas, while S in CS forms an elementary substance or binds to M in the oxide raw materials, and finally produces a sulfide electrolyte under a heating condition.

[0081] In step 160, after the cooling, a product, namely, a sulfide solid electrolyte, is removed from the heating furnace.

[0082] Preferably, the resulting product is placed in a glove box and then stored in an inert atmosphere, a vacuum environment, or a dry room with a dew point of 50 C.

[0083] The technical solution of the method for gas phase synthesis according to the disclosure facilitates the synthesis at the temperature of about 500 C. by optimizing the gas flow value (achieved by precisely adjusting the gas flow meter), the size of pipelines of the heating furnace, the heating and cooling rates and other parameters, whereby the measured yield is close to 100%, and 2 g of materials can be synthesized in a single batch in the laboratory.

[0084] The sulfide solid-electrolyte material synthesized with the above method for gas phase synthesis can be used in electrode materials, including positive and negative electrode materials, for lithium batteries.

[0085] In addition to the synthesis of the sulfide solid-electrolyte material, the above method for gas phase synthesis can be used to synthesize a raw material for the sulfide solid-electrolyte material. The synthesized raw material for the sulfide solid-electrolyte material has a chemical formula of A.sub.xS.sub.y, with A being any one of lithium (Li), silicon (Si), germanium (Ge), tin (Sn), phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi), wherein 0<x2, and 0<y5. For example, Li.sub.2S and other materials that are expensive at present can be synthesized with the present method.

[0086] The following is explained in combination with the flowchart of the method for gas phase synthesis of a raw material for a sulfide solid-electrolyte material as shown in FIG. 3.

[0087] In step 210, an A source is weighed out according to a desired amount, and then put into the heating furnace.

[0088] The A source includes an oxide of A, a hydroxide of A, a carbonate of A, or elemental A.

[0089] For example, the A source is the lithium (Li) source, including at least one of Li.sub.2CO.sub.3, Li.sub.2O, LiOH, or lithium metal. A.sub.xS.sub.y is Li.sub.2S.

[0090] For example, the A source is the silicon (Si) source, including elemental Si, SiO.sub.2, and SiO. A.sub.xS.sub.y is SiS.sub.2.

[0091] For example, the A source is the germanium (Ge) source, including elemental Ge and GeO.sub.2. A.sub.xS.sub.y is GeS.sub.2.

[0092] For example, the A source is the tin (Sn) source, including elemental Sn, SnO.sub.2, and Sn.sub.2O.sub.3; and A.sub.xS.sub.y is SnS.sub.2.

[0093] For example, the A source is the phosphorus (P) source, including elemental P, P.sub.2O.sub.3, and P.sub.2O.sub.5; and A.sub.xS.sub.y is P.sub.2S.sub.5.

[0094] For example, the A source is the arsenic (As) source, including elemental As, As.sub.2O.sub.5, and As.sub.2O.sub.3; and A.sub.xS.sub.y is As.sub.2S.sub.3 and/or As.sub.2S.sub.5.

[0095] For example, the A source is the antimony (Sb) source, including elemental Sb, Sb.sub.2O.sub.3, and Sb.sub.2O.sub.5; and A.sub.xS.sub.y is Sb.sub.2S.sub.3 and/or Sb.sub.2S.sub.5.

[0096] For example, the A source is the bismuth (Bi) source, including elemental Bi and Bi.sub.2O.sub.3; and A.sub.xS.sub.y is Bi.sub.2S.sub.3.

[0097] In step 220, a sulfur (S) source is added to a sulfur-source gas generation device.

[0098] The S source specifically includes one or more of an S-containing gas, a sulfur-containing organic compound, a polysulfide, a sulfate, or a metal sulfide. Further specifically, the S-containing gas includes: at least one of hydrogen sulfide, sulfur dioxide, sulfur trioxide, sulfur-containing natural gas, sulfur vapor, and carbon disulfide vapor.

[0099] The sulfur-containing organic compound includes: at least one of methyl mercaptan, methyl sulfide, dimethyl disulfide, thiophene, ethanethiol, ethyl sulfide, methyl ethyl sulfide, and thiourea.

[0100] In the S source, the polysulfide may be decomposed in an acidic solution to produce H.sub.2S and S; the sulfate may be thermochemically reduced with an organic matter to produce H.sub.2S; and the metal sulfide may react with hydrochloric acid or sulfuric acid to produce H.sub.2S. Consequently, the gas containing the S source that can be carried by the carrier gas is produced.

[0101] In step 230, a carrier gas generation device, a gas flow meter, the sulfur-source gas generation device, the heating furnace, and a tail gas treatment device are connected in sequence to form a gas phase synthesis device.

[0102] The gas phase synthesis device in this embodiment is the same as that in the previous embodiment, and will not be repeated.

[0103] In step 240, a gas containing the S source is carried by a carrier gas, and gas washing is performed on the heating furnace for a certain period of time at a set ventilation rate.

[0104] The specific process is the same as step 140, and will not be repeated.

[0105] In step 250, after the gas washing is completed, the heating furnace is heated to 200 C.-800 C. at a set heating rate in an environment in which the gas containing the S source is introduced at a set ventilation rate, the temperature was held for a set period of time, and then the furnace is cooled to room temperature.

[0106] Specifically, ventilation conditions are the same as the steps of gas washing.

[0107] The set heating rate is within a range from 1 C./minute to 10 C./minute.

[0108] The cooling can be specifically performed at a set cooling rate within a range of 1 C./minute to 10 C./minute, or by natural cooling.

[0109] In step 260, after the cooling, a substance, namely, the raw material for the sulfide solid electrolyte, is removed from the heating furnace.

[0110] By means of the above method, raw materials such as Li2S for the synthesis of the sulfide solid-electrolyte materials can be prepared, whereby the problem that these raw materials are expensive and difficult to obtain is solved.

[0111] In order to better understand the technical solutions provided by the disclosure, a plurality of specific examples are described below to illustrate the specific processes and material characteristics of the sulfide solid-electrolyte materials synthesized using the methods provided in the aforementioned embodiments of the disclosure.

Example 1

[0112] In this example, low-cost Li.sub.2CO.sub.3, CS.sub.2, and SnO.sub.2 that had been commercialized were selected as a lithium (Li) source, a sulfur (S) source, and a tin (Sn) source, respectively, to synthesize a sulfide electrolyte Li.sub.4SnS.sub.4. The specific steps were as follows: [0113] (1) Li.sub.2CO.sub.3 and SnO.sub.2 were weighed out as raw materials according to a desired ratio, and were ground for 30 minutes in a mortar to obtain powder with a total mass of 2 g, and the powder was put into two alumina crucibles (1 g per crucible); [0114] (2) 80 mL of a CS.sub.2 liquid was added to a gas-washing bottle with a capacity of 100 mL; [0115] (3) the two crucibles containing the raw materials in step (1) were put, side by side, into the center of a quartz tube of a tube furnace, directly opposing a thermocouple; [0116] (4) a nitrogen cylinder, a gas flow meter, the gas washing bottle, the tube furnace, and a tail gas bottle were connected in sequence by using silicone hoses, and both ends of the quartz tube of the tube furnace were each connected with a flange; [0117] (5) a knob of the gas flow meter was adjusted to regulate the ventilation rate to 10 mL/minute, and gas washing was performed for about 60 minutes in advance; [0118] (6) after the gas washing in step (5) was completed, the tube furnace was heated from the room temperature of 30 C. to 500 C. at a heating rate of 5 C./minute under the same ventilation condition, the temperature was held for 24 hours, and then cooling was performed at a cooling rate of 2 C./minute; and [0119] (7) after the cooling was completed, the flange at one end of the quartz tube was detached, and the crucibles were taken out to obtain the solid electrolyte Li.sub.4SnS.sub.4.

[0120] The solid electrolyte Li.sub.4SnS.sub.4 obtained in this example has good air stability. After being exposed to and absorbing water in moist air, the solid electrolyte Li.sub.4SnS.sub.4 can be heated to remove water/crystal water, thereby restoring an original crystal structure.

Example 2

[0121] In this example, low-cost Li.sub.2CO.sub.3, CS.sub.2, SnO.sub.2, and Sb.sub.2O.sub.5 that had been commercialized were selected as an Li source, an S source, an Sn source, and an Sb source, respectively, to synthesize a sulfide electrolyte Li.sub.3.85Sn.sub.0.85Sb.sub.0.15S.sub.4. The specific steps were as follows: [0122] (1) Li.sub.2CO.sub.3, SnO.sub.2, and Sb.sub.2O.sub.5 were weighed out as raw materials according to a desired ratio, and were ground for 30 minutes in a mortar to obtain powder with a total mass of 1 g, and the powder was put into an alumina crucible; [0123] (2) 80 mL of a CS.sub.2 liquid was added to a gas-washing bottle with a capacity of 100 mL; [0124] (3) the crucible containing the raw materials in step (1) was put into the center of a quartz tube of a tube furnace, directly opposing a thermocouple; [0125] (4) a nitrogen cylinder, a gas flow meter, the gas washing bottle, the tube furnace, and a tail gas bottle were connected in sequence by using silicone hoses, and both ends of the quartz tube of the tube furnace were each connected with a flange; [0126] (5) a knob of the gas flow meter was adjusted to regulate the ventilation rate to 10 mL/minute, and gas washing was performed for about 60 minutes in advance; [0127] (6) after the gas washing in step (5) was completed, the tube furnace was heated from the room temperature of 30 C. to 500 C. at a heating rate of 5 C./minute under the same ventilation condition, the temperature was held for 24 hours, and then cooling was performed at a cooling rate of 2 C./minute; and [0128] (7) after the cooling was completed, the flange at one end of the quartz tube was detached, and the crucible was taken out to obtain the solid electrolyte Li.sub.3.85Sn.sub.0.85Sb.sub.0.15S.sub.4.

[0129] The solid electrolyte Li.sub.3.85Sn.sub.0.85Sb.sub.0.15S.sub.4 obtained in this example has good air stability. After being exposed to and absorbing water in moist air, the solid electrolyte Li.sub.3.85Sn.sub.0.85Sb.sub.0.15S.sub.4 can be heated to remove water/crystal water, thereby restoring an original crystal structure.

Example 3

[0130] In this example, low-cost Li.sub.2CO.sub.3, CS.sub.2, SnO.sub.2, and As.sub.2S.sub.3 that had been commercialized were selected as a lithium (Li) source, sulfur (S) source, a tin (Sn) source, and an arsenic (As) source, respectively, to synthesize a sulfide electrolyte Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4. The specific steps were as follows: [0131] (1) Li.sub.2CO.sub.3, SnO.sub.2, and As.sub.2S.sub.3 were weighed out as raw materials according to a desired ratio, and were ground for 30 minutes in a mortar to obtain powder with a total mass of 1 g, and the powder was put into an alumina crucible; [0132] (2) 80 mL of a CS.sub.2 liquid was added to a gas-washing bottle with a capacity of 100 mL; [0133] (3) the crucible containing the raw materials in step (1) was put into the center of a quartz tube of a tube furnace, directly opposing a thermocouple; [0134] (4) a nitrogen cylinder, a gas flow meter, the gas washing bottle, the tube furnace, and a tail gas bottle were connected in sequence by using silicone hoses, and both ends of the quartz tube of the tube furnace were each connected with a flange; [0135] (5) a knob of the gas flow meter was adjusted to regulate the ventilation rate to 10 mL/minute, and gas washing was performed for about 60 minutes in advance; [0136] (6) after the gas washing in step (5) was completed, the tube furnace was heated from the room temperature of 30 C. to 500 C. at a heating rate of 5 C./minute under the same ventilation condition, the temperature was held for 24 hours, and then the furnace was cooled naturally; and [0137] (7) after the cooling was completed, the flange at one end of the quartz tube was detached, and the crucible was taken out to obtain the solid electrolyte Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4.

[0138] The solid electrolyte Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4 obtained in this example has good air stability. After being exposed to and absorbing water in moist air, the solid electrolyte Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4 can be heated to remove water/crystal water, thereby restoring an original crystal structure.

Example 4

[0139] In this example, low-cost Li.sub.2CO.sub.3, CS.sub.2, SnO.sub.2, and micron-sized elemental silicon powder that had been commercialized were selected as a lithium (Li) source, a sulfur (S) source, a tin (Sn) source, and a silicon (Si) source, respectively, to synthesize a sulfide electrolyte Li.sub.4Sn.sub.0.9Si.sub.0.1S.sub.4. The specific steps were as follows: [0140] (1) Li.sub.2CO.sub.3, SnO.sub.2, and Si were weighed out as raw materials according to a desired ratio, and were ground for 30 minutes in a mortar to obtain powder with a total mass of 1 g, and the powder was put into an alumina crucible; [0141] (2) 80 mL of a CS.sub.2 liquid was added to a gas-washing bottle with a capacity of 100 mL; [0142] (3) the crucible containing the raw materials in step (1) was put into the center of a quartz tube of a tube furnace, directly opposing a thermocouple; [0143] (4) a nitrogen cylinder, a gas flow meter, the gas washing bottle, the tube furnace, and a tail gas bottle were connected in sequence by using silicone hoses, and both ends of the quartz tube of the tube furnace were each connected with a flange; [0144] (5) a knob of the gas flow meter was adjusted to regulate the ventilation rate to 10 mL/minute, and gas washing was performed for about 60 minutes in advance; [0145] (6) after the gas washing in step (5) was completed, the tube furnace was heated from the room temperature of 30 C. to 500 C. at a heating rate of 5 C./minute under the same ventilation condition, the temperature was held for 24 hours, and then cooling was performed at a cooling rate of 2 C./minute; and [0146] (7) after the cooling was completed, the flange at one end of the quartz tube was detached, and the crucible was taken out to obtain the solid electrolyte Li.sub.3.8Sn.sub.0.8Si.sub.0.2S.sub.4.

[0147] The solid electrolyte Li.sub.3.8Sn.sub.0.8Si.sub.0.2S.sub.4 obtained in this example has good air stability. After being exposed to and absorbing water in moist air, the solid electrolyte Li.sub.3.8Sn.sub.0.8Si.sub.0.2S.sub.4 can be heated to remove water/crystal water, thereby restoring an original crystal structure.

[0148] The components and electrochemical properties of sulfide solid electrolytes Li.sub.4SnS.sub.4Li.sub.3.85Sn.sub.0.85Sb.sub.0.15S.sub.4, Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4, and Li.sub.4Sn.sub.0.9Si.sub.0.1S.sub.4, of the LiSnS system, prepared according to Examples 1, 2, 3 and 4 were characterized using many test methods, with the results as below. [0149] 1. The products obtained in Examples 1, 2, 3, and 4 were determined by X-ray diffraction using CuK.sub. rays with a wavelength of 1.5418 angstroms, with the results as shown in FIG. 4. From the figure, it can be seen that the XRD results of the products obtained in Examples 1, 2, 3 and 4 are consistent with the main peaks of the PDF card, and these products pertain to the Pnma(No. 62) space group of the orthorhombic crystal system, and are LiSnS system crystalline materials. Li.sub.4SnS.sub.4 prepared in Example 1 contains Li.sub.2SnS.sub.3 as an impurity phase, which disappears after doping, whereby the purity is increased. [0150] 2. 150 mg of the electrolyte material was pressed into a cake under a pressure of 800 MPa by using a pressure mold. A test battery with a C/SSE/C sandwich structure was assembled by using a simulated battery case. On a Zahniumpro electrochemical workstation, the test battery was tested, with perturbations of 5-20 mV, for an alternating-current impedance spectrum in a frequency range of 100 mHz-8 MHz. The results were displayed in the form of a Nyquist diagram as shown in FIG. 5. The thickness of the electrolyte sheet was measured by using a micrometer caliper, and the diameter of the electrolyte sheet was equal to the diameter of the mold, which was 10 mm. According to a conductivity formula, the ionic conductivities of Li.sub.4SnS.sub.4, Li.sub.3.85Sn.sub.0.85Sb.sub.0.15S.sub.4, Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4, and Li.sub.4Sn.sub.0.9Si.sub.0.1S.sub.4 were calculated as 4.7510.sup.5 S/cm.sup.1, 1.6210.sup.4 S/cm.sup.1, 1.6610.sup.3 S/cm.sup.1, and 1.6810.sup.5 S/cm.sup.1, respectively. [0151] 3. The test battery described in Result 2 was put into a high/low-temperature precise control cabinet to allow alternating-current impedance tests at different temperatures, thereby measuring impedance values at respective temperature points. Then, the ionic conductivity was calculated for plotting Arrhenius curves. From FIG. 6, it can be seen that the activation energies of the electrolytes prepared in Examples 1 and 2 are 0.453 eV and 0.425 eV, respectively.

Example 5

[0152] In this example, low-cost Li.sub.2CO.sub.3, CS.sub.2, SnO.sub.2, and P.sub.2O.sub.5 that had been commercialized were selected as a lithium (Li) source, a sulfur (S) source, a tin (Sn) source, and a phosphorus (P) source, respectively, to synthesize a sulfide electrolyte Li.sub.10SnP.sub.2S.sub.12. The specific steps were as follows: [0153] (1) Li.sub.2CO.sub.3, SnO.sub.2, and P.sub.2O.sub.5 were weighed out as raw materials according to a desired ratio, and were ground for 30 minutes in a mortar to obtain powder with a total mass of 1 g, and the powder was put into an alumina crucible; [0154] (2) 80 mL of a CS.sub.2 liquid was added to a gas-washing bottle with a capacity of 100 mL; [0155] (3) the crucible containing the raw materials in step (1) was put into the center of a quartz tube of a tube furnace, directly opposing a thermocouple; [0156] (4) a nitrogen cylinder, a gas flow meter, the gas washing bottle, the tube furnace, and a tail gas bottle were connected in sequence by using silicone hoses, and both ends of the quartz tube of the tube furnace were each connected with a flange; [0157] (5) a knob of the gas flow meter was adjusted to regulate the ventilation rate to 10 mL/minute, and gas washing was performed for about 60 minutes in advance; [0158] (6) after the gas washing in step (5) was completed, the tube furnace was heated from the room temperature of 30 C. to 500 C. at a heating rate of 5 C./minute under the same ventilation condition, the temperature was held for 24 hours, and then the furnace was cooled naturally; and [0159] (7) after the cooling was completed, the flange at one end of the quartz tube was detached, and the crucibles were taken out to obtain the solid electrolyte Li.sub.10SnP.sub.2S.sub.12.

[0160] The components of Li.sub.10SnP.sub.2S.sub.12 prepared in Example 5 were characterized with the results as below.

[0161] The obtained product Li.sub.10SnP.sub.2S.sub.12 was determined by X-ray diffraction using CuK.sub. rays with a wavelength of 1.5418 angstroms, with the results as shown in FIG. 7. A high/low-temperature EIS test was performed on the electrolyte to obtain EISs corresponding to different temperature points. The ionic conductivity corresponding to each temperature point was calculated from the ionic conductivity calculation formula and the measured thickness and area of the electrolyte, whereby the ionic conductivities were fitted to obtain an Arrhenius curve as shown in FIG. 8, and the activation energy was calculated finally.

Example 6

[0162] This example provides the process of preparing the raw material Li.sub.2S for the sulfide electrolyte by using a method for gas phase synthesis. Low-cost Li.sub.2CO.sub.3 and CS.sub.2 that had been commercialized were selected as a lithium (Li) source and a sulfur (S) source, respectively, to synthesize a currently expensive raw material Li.sub.2S for the sulfide electrolyte. The specific steps were as follows: [0163] (1) Li.sub.2CO.sub.3 powder with the total mass of 1 g was put in an alumina crucible; [0164] (2) 80 mL of a CS.sub.2 liquid was added to a gas-washing bottle with a capacity of 100 mL; [0165] (3) the crucible containing the raw materials in step (1) was put into the center of a quartz tube of a tube furnace, directly opposing a thermocouple; [0166] (4) a nitrogen cylinder, a gas flow meter, the gas washing bottle, the tube furnace, and a tail gas bottle were connected in sequence by using silicone hoses, and both ends of the quartz tube of the tube furnace were each connected with a flange; [0167] (5) a knob of the gas flow meter was adjusted to regulate the ventilation rate to 10 mL/minute, and gas washing was performed for about 60 minutes in advance; [0168] (6) after the gas washing in step (5) was completed, the tube furnace was heated from the room temperature of 30 C. to 500 C. at a heating rate of 5 C./minute under the same ventilation condition, the temperature was held for 24 hours, and then cooling was performed at a cooling rate of 2 C./minute; and [0169] (7) after the cooling was completed, the flange at one end of the quartz tube was detached, and the crucibles were taken out to obtain the raw material Li.sub.2S for the solid electrolyte.

[0170] The components of Li.sub.2S prepared in this example were characterized with the results as below.

[0171] The obtained product Li.sub.2S was determined by X-ray diffraction using CuK.sub. rays with a wavelength of 1.5418 angstroms, with the results as shown in FIG. 9. Compared with the PDF card 65-2981 of Li.sub.2S, except for the peak at 21.5 which was from a PE film protective material used in the XRD test, the remaining 8 diffraction peaks are in one-to-one correspondence.

Example 7

[0172] This example provides the specific application of the solid electrolyte Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4 prepared in Example 3 to an electrode material.

[0173] In this example, Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4 synthesized in Example 3 was taken as a solid electrolyte, LiCoO.sub.2 coated with LiNbO.sub.2 was taken as a positive-electrode active material, Li.sub.4Ti.sub.5O.sub.12 was taken as a negative-electrode active material, and a carbon nano-tube (VGCF) was taken as a conductive additive. A lithium battery was prepared according to the method including the steps below. [0174] (1) Li.sub.4Ti.sub.5O.sub.12 as the active material, Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4 as the solid electrolyte, and VGCF as the conductive additive were weighed out by mass according to a desired ratio, then ground in a mortar, and mixed into a negative electrode material. [0175] (2) LiCoO.sub.2 as the active material, Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4 as the solid electrolyte, and VGCF as the conductive additive were weighed out by mass according to a desired ratio, then ground in a mortar, and mixed into a positive electrode material. [0176] (3) 2.5 mg of the negative electrode material was weighed out and put into a battery mold, and the surface of a powder layer was smoothed using a stainless steel mold; then, 100 mg of the solid-electrolyte material Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4 was weighed out and put into the battery mold, and the surface of a powder layer was smoothed using the stainless steel mold; and 2 mg of the positive electrode material was weighed out and put into the battery mold, and the surface of a power layer was smoothed using the stainless steel mold. The pressure applied to the entire battery was increased to 30 MPa by using a pressing machine, screws were tightened, and the battery was sealed by applying vacuum silicone grease so as to isolate moist and oxygen in the air. [0177] (4) The battery was connected to a LAND test channel, and a charge/discharge cycle program was set to charge and discharge the battery at a rate of 0.1C. Initial-cycle charge/discharge curves are shown in FIG. 10, in which an all-solid-state powder battery assembled from the electrolyte Li.sub.3.8Sn.sub.0.8As.sub.0.2S.sub.4 shows an initial-cycle discharge capacity up to and an initial-cycle coulombic efficiency of 79.11%.

[0178] The method for gas phase synthesis of the sulfide solid-electrolyte material according to the disclosure uses air-stable and low-cost raw materials to synthesize the sulfide solid-electrolyte material and the raw material thereof in one step by a gas phase method, greatly simplifying the process steps and the operating complexity and showing low requirements for synthesis equipment. The method is suitable for large-scale process production. In the method for synthesis of the sulfide solid-electrolyte material, due to the use of air-stable raw materials and the good air stability of the synthesized sulfide solid-electrolyte material, the method for synthesis does not need to be performed under the condition of a vacuum environment or with the protection of an inert atmosphere, and can be performed directly in an air environment (moist air and dry air in a dry room), such that the air stability is achieved throughout the process of preparing the sulfide solid-electrolyte material from raw materials to a final reaction product, and the compatibility with the existing process lines and equipment for producing lithium batteries in a dry room environment is achieved. Further, the disclosure fundamentally solves the problem of strict requirements for the environmental atmosphere during production and preparation, storage, transportation, and usage of the sulfide solid-electrolyte materials, greatly promoting the application of the sulfide solid-electrolyte materials.

[0179] The objects, technical solutions and advantageous effects of the disclosure are further illustrated in detail with the specific embodiments described above. It should be understood that the description above only involves the specific embodiments of the disclosure and is not intended to limit the protection scope of the disclosure. Any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention shall be construed as being included within the protection scope of the disclosure.