CN115775657A - Method and apparatus for producing ion conductor - Google Patents

Abstract

The invention provides a preparation method and a preparation device of an ion conductor with high ionic conductivity. The production method is characterized in that a 1 st compound having a 1 st cation and a 1 st anion as a counter ion thereof is dissolved in a solvent to form a 1 st solution; exchanging at least a portion of the 1 st cation or the 1 st anion in the 1 st compound with a2 nd cation or a2 nd anion using an ion exchange method to obtain a2 nd compound, and dissolving the 2 nd compound in the above solvent to obtain a2 nd solution containing an ionic conductor. The solvent may be a deoxygenated solvent or a solvent containing a deoxygenated solvent. The preparation process is carried out in a closed preparation device under the condition of not contacting with air.

Description

Preparation method and preparation device of ion conductor

technical field

The invention relates to a preparation method and a preparation device of a sulfide solid ion conductor, and the sulfide solid ion conductor produced by the method, especially the technology of the sulfide solid ion conductor in an all-solid secondary battery using lithium.

Background technique

In recent years, development of lithium-ion batteries, sodium-ion batteries, and polyvalent ion batteries typified by magnesium secondary batteries has been actively promoted as batteries that achieve high energy density. Among them, lithium-ion batteries have the characteristics of high energy density and long life. Therefore, lithium-ion batteries are generally widely used as power sources for personal computers, home appliances (such as cameras), portable electronic devices and communication devices (such as mobile phones), and power tools. In recent years, lithium-ion batteries have also been widely used in large-scale batteries such as electric vehicles and hybrid electric vehicles, and stationary storage batteries. In these kinds of Li-ion batteries, when a solid electrolyte is used instead of an electrolyte containing a flammable organic solvent, not only the safety device can be simplified, but also the preparation cost and production efficiency are excellent. Preparation methods of various solid electrolytes have been actively studied.

Patent Document 1 discloses a method of producing a solid ion conductor by obtaining an aqueous Li ₄ SnS ₄ solution by cation exchange from an aqueous Na ₄ SnS ₄ solution prepared in an air environment using non-deoxygenated water.

[Prior Art Literature]

【Patent Literature】

[Patent Document 1] Japanese Patent Laid-Open No. 2019-102355

Contents of the invention

The technical problem to be solved by the present invention

However, when the present inventors prepared Li ₄ SnS ₄ by the method described in Patent Document 1, since the ionic conductivity of the obtained Li ₄ SnS ₄ did not meet expectations, its preparation took a long time, and we found that it has not yet reached a practical level .

Therefore, the present invention aims to provide a method and device for preparing an ion conductor, which can obtain an ion conductor with high ion conductivity.

Technical Solutions to Solve Technical Issues

The present invention provides a method for preparing an ion conductor. A first compound having at least a first cation and a first anion as its counter ion is dissolved in a solvent to form a first solution, and the first solution is formed by using an ion exchange method. At least a part of the first cation or the first anion in the compound is exchanged for a second cation or a second anion to obtain a second compound, and the second compound is dissolved in the above solvent to obtain a second solution containing an ion conductor, The solvent includes a deoxygenated solvent, and the preparation of the ion conductor is carried out without contact with air.

In the production method of the ion conductor of the present invention, it is preferable that the solvent contains water.

In the preparation method of the ion conductor of the present invention, preferably, the dissolved oxygen concentration of the solvent is lower than 8 mg-O/L.

The method for producing an ion conductor according to the present invention preferably further includes a drying step of removing the solvent from the second solution to obtain an ion conductor.

In the preparation method of the ion conductor of the present invention, an inert atmosphere with an oxygen content of less than 1000 ppm and a CO ₂ content of less than 100 ppm is preferably used.

The present invention also provides an ion conductor prepared according to any one of the above preparation methods, wherein the ion conductor has a median diameter D50 of 0.05-500 μm.

The present invention also provides a preparation device for preparing the ion conductor, comprising:

Ultrapure water equipment, the ultrapure water equipment is used to prepare ultrapure water as a deoxygenated solvent;

A first airtight reaction vessel, the first airtight reaction vessel is in fluid communication with the ultrapure water equipment, and is used to dissolve SnCl ₄ 5H ₂ O through the deoxygenation solvent, and prepare a SnCl ₄ solution;

The second airtight reaction vessel, the second airtight reaction vessel is in fluid communication with the first airtight reaction vessel and the ultrapure water equipment, for dissolving Na ₂ S through the deoxygenated solvent to obtain Na ₂ S solution, and dissolving the SnCl ₄ solution is mixed with the Na ₂ S solution to prepare a suspension of SnS ₂ +NaCl;

A third airtight reaction vessel, the third airtight reaction vessel is in fluid communication with the ultrapure water equipment, and is used to dissolve _Na2S through the deoxygenated solvent to obtain a _Na2S solution;

A separation membrane unit, the separation membrane unit is in fluid communication with the ultrapure water device, the second closed reaction vessel and the third closed reaction vessel, and is used to filter and separate the suspension of SnS ₂ +NaCl and prepare SnS ₂ dispersion liquid, which is also used to pass through the Na ₂ S solution in the third closed reaction vessel and react with SnS ₂ to prepare Na ₄ SnS ₄ solution as the first solution;

A fourth airtight reaction container, the fourth airtight reaction container is in fluid communication with the ultrapure water equipment and the separation membrane unit, and is used to store the first solution and prevent the first solution from deteriorating;

An airtight ion exchange tower, which is in fluid communication with the ultrapure water device and the fourth airtight reaction vessel, is used to exchange Na ions in the Na ₄ SnS ₄ solution for Li ions, and the Li-type ion exchange resin Prepare Li ₄ SnS ₄ solution under action as the second solution;

A closed recovery container, the closed recovery container is in fluid communication with the closed ion exchange tower, and is used for storing Li ₄ SnS ₄ solid powder or particles obtained after drying the Li ₄ SnS ₄ solution.

With this technical scheme, in the process of preparing Li ₄ SnS ₄ , SnCl ₄ 5H ₂ O and Na ₂ S are put into the first closed reaction vessel and the second closed reaction vessel respectively, because the first closed reaction vessel and the second closed reaction The containers are all in fluid communication with the ultrapure water equipment. In the first closed reaction vessel, the SnCl ₄ solution can be obtained by using the deoxygenated solvent prepared by the ultrapure water equipment and SnCl ₄ 5H ₂ O; in the second closed reaction vessel, the ultrapure Deoxygenated solvent and Na ₂ S prepared by pure water equipment to obtain Na ₂ S solution, then in the second closed reaction vessel, the SnCl ₄ solution and the Na ₂ S solution are stirred and reacted to be a suspension of SnS ₂ +NaCl; in the third In a closed reaction vessel, use the deoxygenated solvent and Na ₂ S prepared by ultrapure water equipment to obtain Na ₂ S solution; filter and separate the NaCl aqueous solution in the SnS ₂ +NaCl suspension in the separation membrane unit to obtain the SnS ₂ dispersion , dissolving the SnS ₂ dispersion in the Na ₂ S solution to prepare the Na ₄ SnS ₄ solution; storing the Na ₄ SnS ₄ solution in the fourth closed reaction vessel; in the closed ion exchange tower, dissolving the Na ions in the Na ₄ SnS ₄ solution Li ₄ SnS ₄ solution can be obtained by replacing with Li ions, and finally Li ₄ SnS ₄ solution can be dried to obtain Li ₄ SnS ₄ solid powder or granules. In the above-mentioned process, it is not only more convenient to use the preparation device, but also Li elements, Sn elements, and S elements are exposed to O in a _shorter time, and reduce the oxygen and carbon dioxide (preparation atmosphere, The amount of solvent, oxygen and carbon dioxide contained in the ion exchange resin) is used. Furthermore, the combination of Li element, Sn element, S element and O element can be suppressed, the purity of Li ₄ SnS ₄ can be improved, and the ion conductivity can be improved.

Therefore, the use of the ion conductor preparation device provided in this embodiment can reduce the interference of external factors, make it more convenient to use, and help improve the preparation efficiency of Li ₄ SnS ₄ .

Preferably, the ultrapure water equipment includes an ultrapure water storage unit and a deoxygenation filter; wherein, the outlet end of the ultrapure water storage unit is connected with a connecting pipeline, and the ultrapure water storage unit is connected to the first closed reaction vessel and the second closed reaction vessel respectively. The reaction vessel, the third closed reaction vessel, the separation membrane unit, the fourth closed reaction vessel and the closed ion exchange tower are in fluid communication through a connecting pipeline; the deoxygenation filter is connected to the connecting pipeline at the outlet of the ultrapure water storage unit.

Preferably, the preparation device of the ion conductor also includes an inert gas tank, and the first closed reaction vessel, the second closed reaction vessel, the third closed reaction vessel, the separation membrane unit, and the fourth closed reaction vessel are connected to the inert gas tank pipelines respectively .

Preferably, the ion conductor preparation device further includes a vacuum pump, and the first closed reaction vessel, the second closed reaction vessel, the third closed reaction vessel, the separation membrane unit, and the fourth closed reaction vessel are respectively connected to the vacuum pump pipeline.

Beneficial technical effect

According to the present invention, a solid ion conductor having high ion conductivity can be obtained in a short time.

Description of drawings

Figure 1 is a schematic diagram of an apparatus used in an ion exchange process according to an embodiment of the present invention.

[Symbol Description]

W-1 ultrapure water equipment

V-1 vacuum pump

V-2 vacuum pump

OF deoxidation filter

G-1 inert gas tank

1-a Airtight reaction vessel

1-b Closed reaction vessel

2-a Separation membrane unit

3-a Closed reaction vessel

3-b Closed reaction vessel

4-a Closed ion exchange tower

4-b Airtight recovery container

P1-4 inert gas supply pipe

R1-5 degassing water supply pipe

C1-2 circulation infusion tube

TP-1 High Pressure Liquid Feed Pump

TP-2 liquid delivery pump

TP-3 liquid feed pump

TP-4 liquid feed pump

E-1 closed drain

ST non-through stirring device

Detailed ways

<Preparation method of ion conductor>

The method of producing an ion conductor according to the present invention has the following processes. A process of preparing a first compound having at least a first cation and a first anion as its counter ion, and dissolving it in a solvent to obtain a first solution. A process of exchanging at least a part of the first cation or the first anion in the first compound for a second compound having a second cation or a second anion by using an ion exchange method. A process in which the second compound is dissolved in the solvent to obtain a second solution. A drying process for preparing a solid ion conductor by removing the solvent from the second solution. Each process is described in detail below.

[Process for producing the first solution]

In the process of producing the first solution, a first compound having a first cation and a first anion as its counterion is dissolved in a solvent to obtain a first solution. In this process, one compound having a first cation and another compound having a first anion as its counter ion are respectively dissolved in a solvent and mixed to obtain a first solution. In addition, in the process of preparing the first solution, if a compound containing non-exchanged anions is produced by subsequent ion exchange, a step of separating the non-exchanged anions during the preparation of the first solution may be included.

[Ion exchange process]

In the ion exchange process, an ion exchange method is used to exchange at least a part of the first cation or the first anion of the first compound in the first solution with the second cation or the second anion. Therefore, at least a part of the first cations or first anions in the first solution is exchanged for the second cations or second anions in the second solution. In the ion exchange process, at least a part of the cations (first cations) contained in the first compound may be ion-exchanged with second cations by using a cation exchange method. In addition, at least a part of the anions (first anions) contained in the first compound may be ion-exchanged with second anions by using an anion exchange method.

(ion exchange method)

The ion exchange method may be a cation exchange method or an anion exchange method.

[Cation exchange method]

When performing the ion exchange process using the cation exchange method, the cation exchange resin provided with the second cation is brought into contact with the first solution. Therefore, at least a part of the first cations in the first compound contained in the first solution are exchanged with the second cations in the cation exchange resin to obtain a second solution of the second compound containing the second cations and the first anions. The first compound and the second compound when the ion exchange process is performed using the cation exchange method will be described below.

(1st compound)

The first compound has at least a first cation and a first anion as its counterion. The first cation is not particularly limited, and may be a positively charged monatomic ion or molecular ion which loses electrons. Specifically, monatomic ions include hydrogen ions, lithium ions, sodium ions, potassium ions, rubidium ions, cesium ions, magnesium ions, calcium ions, strontium ions, barium ions, aluminum ions, silver ions, and zinc ions. Molecular ions include ammonium ions, PH ⁴⁺ ions, H ₃ O ⁺ ions, H ₂ F ⁺ ions, mercury ions and cycloheptatrienyl cations, etc.

Among them, the first cation is preferably a sodium ion from the viewpoint of versatility.

The above-mentioned first compound having a first cation is a compound containing an electrolyte that is ionized into a cation (first cation) and anion (first anion) when dissolved in a solvent, and is preferably a compound containing an S element. The compound containing S element is preferably a compound whose first anion contains S element, and is more preferably a sulfide. From the viewpoint of the ionic conductivity of the ion conductor containing the second compound obtained after the ion exchange process, it is particularly preferred that the first anion contains both S elements and elements that can form trivalent or tetravalent cations (can be trivalent or tetravalent cations) valence or quaternary price). The elements that can form trivalent or tetravalent cations are not particularly limited, and may be Sn, As, Bi, Ge, Sb and the like. The preferred first anions are SnS ₄ ions, SnS ₃ ions, AsS ₄ ions, GeS ₄ ions, SbS ₄ ions, Sn ₂ S ₆ ions, BiS ₂ ions, AsS ₃ ions, SbS ₃ ions and SbS ₂ ions.

(2nd compound)

The second compound in the second solution is obtained by an ion exchange process using a cation exchange device, wherein at least a part of the first cation in the first compound is ion-exchanged with the second cation provided by the cation exchange device. That is, the second compound is a compound containing the second cation and the first anion. The second cation is a cation different from the first cation. The second cation is not limited to any cation other than the above-mentioned first cation, and may be a monatomic ion or molecular ion that has lost electrons and has a positive charge. Specifically, monatomic ions include hydrogen ions, lithium ions, sodium ions, potassium ions, rubidium ions, cesium ions, magnesium ions, calcium ions, strontium ions, barium ions, aluminum ions, silver ions, and zinc ions. Molecular ions include ammonium ions, PH ⁴⁺ ions, H ₃ O ⁺ ions, H ₂ F ⁺ ions, mercury ions and cycloheptatrienyl cations, etc. From the above ions, an ion different from the first cation is selected according to the first cation of the first compound. If the cation exchange method is a cation exchange resin, the second cation may be selected in consideration of the affinity of the ions for the cation exchange resin. For example, if the first cation has a greater affinity for the cation exchange resin than the second cation, the ion exchange reaction between the first and second cations can proceed efficiently. In the present invention, for example, when the first cation is a sodium ion, the second cation is preferably a lithium ion.

Cation exchange methods include cation exchange resins. Both strongly acidic and weakly acidic cation exchange resins can be used as cation exchange resins. Strongly acidic cation exchange resins are preferred because H-type strongly acidic cation exchange resins have little residual amount or volume change and are easy to handle. Therefore, the cation exchange resin is more preferably an exchange combination containing a sulfonic acid group (—SO ₃ —) and a second cation. In some cases, chelating resins may also be used. The cation exchange resins can be used alone or in combination of two or more cation exchange resins.

Styrenic and acrylic resins are organic polymers that can be used as cation exchange resin matrices.

In this specification, "styrene resin" refers to a resin formed by homopolymerization or copolymerization of styrene or styrene derivatives, and its structural units include 50 wt% or more of styrene or styrene derivatives. Styrene derivatives include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, bromostyrene, and the like. Styrene resin can be copolymerized with other vinyl monomers that can be copolymerized, as long as the main component is homopolymerization or copolymerization of styrene or styrene derivatives. Such vinyl monomers, preferably such as divinylbenzene (o-divinylbenzene, m-divinylbenzene, p-divinylbenzene); ethylene glycol di(meth)acrylate, polyethylene glycol di( One or more of polyfunctional monomers such as alkylene glycol di(meth)acrylate such as meth)acrylate; (meth)acrylonitrile; and methyl (meth)acrylate. It is preferably divinylbenzene, ethylene glycol di(meth)acrylate or polyethylene glycol di(meth)acrylate, and the degree of ethylene polymerization is 4-16. More preferred is divinylbenzene or ethylene glycol di(meth)acrylate, particularly preferred is divinylbenzene.

In this specification, "acrylic resin" means that the polymer monomer contains one or more of acrylic acid, methacrylic acid, acrylate and methacrylate, and the acrylic structural unit, methacrylic structural unit, acrylate The resin whose total content of the structural unit and the methacrylate structural unit is more than 50wt%. The acrylic resin can be acrylic acid homopolymer, methacrylic acid homopolymer, acrylate homopolymer, methacrylate homopolymer, acrylic acid and other monomers (such as acrylate, methacrylic acid, methacrylic acid Copolymers of esters, α-olefins (such as ethylene, divinylbenzene, etc.), methacrylic acid and other monomers (such as acrylic acid, acrylate, methacrylate, α-olefins (such as ethylene, divinylbenzene, etc.) Benzene, etc.), copolymers of acrylate and other monomers (such as acrylic acid, methacrylic acid, methacrylate, α-olefins (such as ethylene, divinylbenzene, etc.), etc.), and methyl One or more of copolymers of acrylate and other monomers (such as acrylic acid, acrylate, methacrylic acid, α-olefins (such as ethylene, divinylbenzene, etc.), etc.). Of these, methacrylic acid-divinylbenzene copolymers or acrylic acid-divinylbenzene copolymers are preferred.

The acrylate is preferably an alkyl acrylate, more preferably a straight-chain or branched-chain alkyl acrylate, and even more preferably a straight-chain alkyl acrylate. The carbon number of the alkyl ester group is preferably 1-4. It is particularly preferred that the acrylate is methyl acrylate or ethyl acrylate.

The methacrylate is preferably an alkyl methacrylate, more preferably a linear or branched alkyl methacrylate, even more preferably a linear alkyl methacrylate. The carbon number of the alkyl ester group is preferably 1-4. It is particularly preferred that the alkyl methacrylate is methyl methacrylate or ethyl methacrylate.

The matrix of the cation exchange resin can be any one of a transparent gel-type resin with a small pore diameter or a macroporous (also called porous or high-porosity) resin with a large pore diameter. Besides, the average pore diameter and specific surface area of the cation exchange resin are not limited.

[Anion exchange method]

When the anion exchange process is performed using the anion exchange method, the anion exchange resin providing the second anion is brought into contact with the first solution. This allows at least a portion of the first anion in the first compound contained in the first solution to exchange with the second anion in the anion exchange resin to obtain a second solution of the second compound containing the first cation and the second anion. In the case of performing an ion exchange process using an anion exchange method, the first compound and the second compound will be described below.

(1st compound)

The first compound has at least a first cation and a first anion as its counter ion. The first anion is not limited to monatomic ions or molecular ions that gain electrons and are negatively charged. Specifically, monatomic ions include fluoride, chloride, bromide, iodide, sulfur, nitrogen, and phosphorus ions. Molecular ions include polystyrene sulfonate ion, acetate ion, bicarbonate ion _, carbonate ion, cyanide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, SnS4 ion, _SnS3 ions, AsS ₄ ions, SnS ₄ ions, Sn ₂ S ₆ ions, BiS _{2 ions, AsS 3 ions} , SbS ₄ ions, AsS ₃ ions, SbS ₃ ions, SbS ₂ ions, SbS ₂ ions, etc.

Among them, the first anion is preferably a polystyrenesulfonate ion from the viewpoint of versatility.

The above-mentioned first compound having a first anion is a compound containing an electrolyte, and when dissolved in a solvent, it is ionized into a cation (first cation) and an anion (first anion). The first cation is not limited to monatomic or molecular ions that have lost electrons and are positively charged. Specifically, monatomic ions include hydrogen ions, lithium ions, sodium ions, potassium ions, rubidium ions, cesium ions, magnesium ions, calcium ions, strontium ions, barium ions, aluminum ions, silver ions, and zinc ions. Molecular ions include ammonium ions, PH ⁴⁺ ions, H ₃ O ⁺ ions, H ₂ F ⁺ ions, mercury ions and cycloheptatrienyl cations, etc. Among them, the first cation is preferably a lithium ion from the viewpoint of versatility.

(2nd compound)

The second compound in the second solution obtained by using the ion exchange process in the anion exchange method is to ionize at least a part of the first anion in the first compound with the second anion included in the anion exchange method. Compounds obtained by exchange. In other words, the first compound is a compound containing a first cation and a second anion. The second anion is an anion different from the first anion. The second anion is not limited to anions other than the above-mentioned first anion, and may be a monatomic or molecular ion that receives electrons and is negatively charged. Specifically, monatomic ions include fluoride, chloride, bromide, iodide, sulfur, nitrogen, and phosphorus ions. Molecular ions include polystyrene sulfonate ion, acetate ion, bicarbonate ion _, carbonate ion, cyanide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, SnS4 ion, _SnS3 ions, AsS ₄ ions, SnS ₄ ions, Sn ₂ S ₆ ions, BiS _{2 ions, AsS 3 ions} , SbS ₄ ions, AsS ₃ ions, SbS ₃ ions, SbS ₂ ions, SbS ₂ ions, etc. Among the ions, an ion different from the first anion is selected according to the first anion contained in the first compound. If the anion exchange method is an anion exchange resin, it can be selected in consideration of the affinity of the second anion with the anion exchange resin. For example, if the first anion has a greater affinity for the anion exchange resin than the second anion, the ion exchange reaction between the first and second anions can proceed efficiently. In the present invention, for example, when the first anion is polystyrenesulfonate ion, the second anion is preferably SnS ₄ ion.

Anion exchange resins are an anion exchange method. Strongly basic anion exchange resins with quaternary ammonium bases and weakly basic anion exchange resins with primary to tertiary amino groups can be used as anion exchange resins. However, from the viewpoint of ion exchange reaction efficiency, it is preferable to use a strongly basic anion exchange resin. Therefore, the anion exchange resin is preferably an exchange combination containing trimethylammonium groups (—N(CH ₃ ) ₃ ) and a second anion. In some cases, chelating resins may also be used. Anion exchange resins can be used alone or in combination of two or more anion exchange resins.

Similar to cation exchange resins, styrene and acrylic acid can be used as organic polymer monomers for anion exchange resin matrix. The matrix of the anion exchange resin can be any one of a transparent gel-type resin with a small pore diameter or a macroporous (also called porous or high-porosity) resin with a large pore diameter. Besides, the average pore diameter and specific surface area of the anion exchange resin are not limited.

The ion exchange process can be repeated. A combination of cation and anion exchange methods can be used as the ion exchange method. For example, if a strongly acidic cation exchange resin is used for the ion exchange process, polystyrene sulfonate derived from the resin matrix eluted from the strongly acidic cation exchange resin may enter the second solution as an impurity. Therefore, in the ion exchange process, the obtained second solution is used again as the first solution, and impurities are removed by passing through an anion exchange resin charged with an anion of interest (second anion). The anion (first anion) in polystyrene sulfonate is exchanged with the second anion to obtain an ion conductor with higher purity.

(solvent)

In the process of preparing the first compound, the process of preparing the first solution, and the ion exchange process, the solvents used in the first solution and the second solution can be water, alcohols such as methanol and ethanol, water-soluble organic solvents such as acetone, and the above A combination of one or more solvents. Among them, the solvent preferably contains water, and the first solution and the second solution are preferably aqueous solutions. Water is preferably pure water or ultrapure water.

In the present invention, the solvent is preferably a deoxygenated solvent or a deoxygenated solvent. In other words, the dissolved oxygen concentration of the solvent is less than the saturated dissolved oxygen concentration of the solvent. Here, for example, when the water temperature is 15° C., the saturated dissolved oxygen concentration is 9.76 mg/liter. And when the water temperature is 25°C, the saturated dissolved oxygen concentration is 8.11 mg/L (see JIS K0102:2013). Therefore, if the solvent contains water, the dissolved oxygen concentration of the solvent (preferably water) should preferably be lower than 8 mg/L, more preferably lower than 5 mg/L, more preferably lower than 3 mg/L. Most preferred is less than 1 mg/L.

The method of deoxygenating the solvent is not limited, and known methods can be used. Specifically, methods such as membrane degassing, replacing oxygen with He, Ne, Ar, Kr, Xe, and Rn gases, using oxygen absorbers, and combinations of these methods.

The method of adjusting the atmosphere is not limited, and known methods can be used. Specifically, replace oxygen with He, Ne, Ar, Kr, Xe, Rn gases, use oxygen adsorbents, carbon dioxide adsorbents, vacuum environments, etc., and combinations of these methods.

The concentration of the first compound in the first solution is not particularly limited, as long as the ion exchange process can be effectively performed. For example, the concentration of the first compound in the first solution may be 1 to 30 wt%, preferably 15 to 20 wt%. However, as described above, when the ion exchange process is repeated, if the ion exchange process is performed again to remove impurities generated in the ion exchange process, the concentration of the impurity (first compound) is not limited to the above range.

The specific operation of the ion exchange process is not limited, and conventional and known methods can be used. Figure 1 shows a schematic diagram of the apparatus used in the ion exchange process in one embodiment of the present invention. For example, the first solution in the storage tank 1 is supplied to the ion exchange resin column 2 filled with the above-mentioned ion exchange resin. Using the pump P, the first solution is passed through the ion exchange resin. The first solution is then passed through an ion exchange resin. This allows at least a part of the first cation or the first anion in the first compound in the first solution to be exchanged for the second cation or the second anion. The second solution flows out from the outlet of the ion exchange resin column 2, wherein at least part of the first cations or first anions in the first compound in the first solution are exchanged for second cations or second anions. The second solution that flows out is collected in storage tank 3. The ion exchange process can also be performed in a batch system. The first solution used in the ion exchange process is preferably an aqueous solution, in which case the resulting second solution is also an aqueous solution.

The temperature for performing the ion exchange process is not limited, for example, it may be between 10°C and 50°C. From the standpoint of exchange efficiency, SV (Space velocity: the volume of liquid flowing per hour divided by the volume of ion exchange resin) is preferably 5h ^-1 or less, more preferably 2h ^-1 or less. In addition, BV (Bed volume: a value obtained by dividing the total volume of the liquid flow by the volume of the ion exchange resin), for example, may be 0.5 L/LR to 20 L/LR. However, the above-mentioned range is an example of liquid passing conditions and can be appropriately adjusted. After passing the first solution, it is preferable to pass an appropriate amount of water through the ion exchange resin to discharge the remaining first solution in the ion exchange resin.

When the ion exchange process is performed using a cation exchange device, as described above, the cation exchange device is preferably a strongly acidic cation exchange resin having a second cation (hereinafter simply referred to as element "M ² "). For example, when a first solution of a sulfur-containing compound (consisting of metal element M1, S element and an element forming a trivalent or tetravalent cation (hereinafter abbreviated as M ³ )) is placed in the ion exchange process, the following reaction proceeds. Therefore, M ² _x M ³ _y S _z is formed as the second compound (compound containing M ² ). x, y, and z represent the molar ratio of each element required to form the compound. R is the matrix of the ion exchange resin.

M ¹ _x M ³ _y S _z +R-SO ₃ M ² →M ² _x M ³ _y S _z +R-SO ₃ M ¹

In the present invention, the above-mentioned cation exchange method is particularly preferably a strongly acidic cation exchange resin equipped with Li ions as M ^ions . For example, the first compound includes a sulfur-containing compound composed of metal element M ¹ , S element and metal element M ³ . When the first solution uses a strongly acidic cation exchange resin loaded with lithium ions for ion exchange process, M ² in the above reaction equation is lithium, and the lithium-containing compound Li _x M ³ _y S _z is obtained after ion exchange. As mentioned above, the second solution containing ^M2 compounds such as lithium-containing compounds can be obtained by the ion exchange process, and if necessary, the second solution can be subjected to the above ion exchange process again. In this case, the ion exchange process can use either the cation exchange method or the anion exchange method.

More specifically, for example, Na ₄ SnS ₄ composed of Na element (M ¹ ), S element, and Sn element (M ³ ) is used as the first compound to prepare the first solution, and an ion having Li (M ² ) is used When the strongly acidic cation exchange resin is used in the ion exchange process, the second solution containing Li ₄ SnS ₄ is obtained as the second compound. In addition, the first compound can be produced by a known method. For example, if the first compound is Na ₄ SnS ₄ , Na ₄ SnS ₄ can be produced through the following two process reactions.

2Na ₂ S+SnCl ₄ →SnS ₂ +4NaCl

SnS ₂ +2Na ₂ S→Na ₄ SnS ₄

Each raw material used for the preparation of the first compound may contain no water, crystal water, or may be a hydrate. Moreover, when each raw material is a solid, it can be used as it is, and can also be used dissolved in water, or it can be used dissolved in the aqueous solution of the above-mentioned water-soluble organic solvent. The solvent constituting the first solution containing the first compound may be a solvent containing an aqueous solution for producing the raw material of the first compound. Therefore, the solvent containing the aqueous solution used to produce the starting material of the first compound preferably includes a deoxygenated solvent. In addition, the dissolved oxygen concentration of the solvent (preferably water) containing the aqueous solution used to produce the raw material of the first compound is preferably lower than 8 mg/L, more preferably lower than 5 mg/L, even more preferably lower than 3 mg/L, particularly preferably lower than 1 mg /L.

[Drying process]

The method for preparing an ion conductor according to the present invention may include a drying process, that is, a process of removing a solvent from a second solution obtained in an ion exchange process to obtain an ion conductor. By removing the solvent in the drying process, the ion conductor mainly containing the second compound can be isolated.

The specific operation of the drying process is not particularly limited, and generally known methods can be applied. That is, freeze-drying (firstly freeze the second solution, then, in a vacuum, lower the boiling point of the freeze-dried product to sublimate the water content of the dried product), heating and reduced-pressure drying (reduce the boiling point in a vacuum heating device, The method of promoting the removal of the solvent from the second solution), spray drying (the method of spraying the second solution into the gas with a spray dryer and drying it quickly to obtain a dry powder), etc., by the above methods, it is possible to recover the dried Ion conductor (second compound). These methods can be used in combination. In addition, only reduced-pressure drying may be performed without heating, or only heat-drying may be performed without reducing pressure. In addition, in the case of obtaining a dry powder by spray drying, in addition to freeze-drying, the recovered second compound may be heat-dried if necessary. When heating, the heating conditions are not particularly limited, and the heating temperature can be set at, for example, 50°C to 300°C. In both cases, it is preferable to set appropriate conditions according to the type of solvent contained in the second solution (first solution).

(craft atmosphere)

In the present invention, the process of preparing the first compound, the process of preparing the first solution, the ion exchange process of ion-exchanging the first solution to obtain the second solution, removing the solvent from the second solution to solidify the ion conductor The atmosphere of the drying process is preferably an atmosphere in which the compound does not side-react with elements or molecules present in the atmosphere in the above-mentioned process. The oxygen content in the air is about 210,000ppm and the _CO2 content is about 400ppm. Therefore, the atmosphere of the process of preparing the first compound, the process of preparing the first solution, the ion exchange process of ion-exchanging the first solution to obtain the second solution, and the drying process of removing the solvent from the second solution to solidify the ion conductor , preferably an atmosphere with an oxygen content of less than 1000ppm and a _CO2 content of less than 100ppm, particularly preferably an atmosphere with an oxygen content of less than 10ppm and a _CO2 content of less than 1ppm.

(ionic conductor)

The ion conductor obtained according to the present invention mainly contains the second compound. However, depending on the treatment conditions in the ion exchange process, components derived from the first compound contained in the first solution may be mixed. Specifically, when using the cation exchange method, components (first cations) derived from the first compound may be mixed in the second solution. In the ion conductor produced by the method of the present invention, the mass fraction of the first compound component contained in the first solution is usually 10 ppm or less, preferably 1 ppm or less.

Ionic conductors prepared according to the present invention can be identified, for example, by measuring and analyzing X-ray diffraction patterns.

The ion conductor (the second compound) prepared according to the present invention is a sulfide, preferably a lithium-containing sulfide, more preferably containing Li, S and M ³ (M ³ can be Sn, As, Bi, Ge, Sb One or more of the sulfides. Specifically, Li ₄ SnS ₄ , Li ₂ SnS ₃ , Li ₃ AsS ₄ , Li ₃ GeS ₄ , Li ₃ SbS ₄ , Li ₄ Sn ₂ S ₆ , LiBiS ₂ , Li ₃ AsS ₃ and Li ₃ SbS ₃ etc. Ion conductors containing such sulfides are suitable as solid electrolytes. The ionic conductor exhibits an ionic conductivity of 1.0×10 ^-4 S/cm or higher at 25°C, and is suitable for use as lithium ion battery materials, such as electrode materials such as positive electrodes and electrolyte layer materials.

[Example 1]

(Preparation of the first solution)

After putting Na ₂ S 9H ₂ O into airtight container 1-a, depressurize to -0.1MPa or lower by vacuum pump V-2, and fill Ar gas from inert gas tank G-1 through gas pipeline P-1 (purity 99.99%). Water is sent to 1-a from the pipe R-1 connected to the ultrapure water device W-1 by the decompression of the vacuum pump V-2 (dissolved oxygen concentration: less than 1mg-O/L, electrical conductivity: less than 1μS/cm ), dissolve Na ₂ S·9H ₂ O. Through this operation, a 12 wt % Na ₂ S aqueous solution (A) was prepared by stirring with deoxygenated water in a deoxygenated atmosphere. Then to the airtight container 1-b, drop SnCl ₄ 5H ₂ O, utilize the vacuum pump V-2 to depressurize to -0.1MPa or lower, and fill Ar gas (purity 99.99% from the inert gas tank G-1 through the gas pipeline P-2 ). Here, water is sent from the pipe R-2 connected to the ultrapure water device W-1 by the decompression of the vacuum pump V-2 (dissolved oxygen concentration: less than 1 mg-O/L, electrical conductivity: less than 1 μS/cm) , dissolve Na ₂ S·9H ₂ O. Through this operation, a 28 wt % Na ₂ S aqueous solution (B) was prepared by stirring with deoxygenated water in a deoxygenated atmosphere. Subsequently, in the airtight container 1-b, under the action of the Ar gas pressure delivered from the inert gas tank G-1 through the gas pipeline P-1, solution A is transported into 1-b, and mixed with solution B by stirring until Na ₂ S:SnCl ₄ =2:1 (molar ratio), so as to obtain 8wt% SnS ₂ dispersion liquid (C) containing NaCl impurity. The inside of the separation membrane 2-a was depressurized to -0.1 MPa or lower by the vacuum pump V-2, and Ar gas (purity 99.99%) was filled from the inert gas tank G-1 through the gas line P-3. The dispersion liquid C is sent to the separation membrane 2-a by the Ar gas pressure of P-2, and the SnS ₂ dispersion liquid containing NaCl is deposited on the separation membrane, and the SnS ₂ precipitation containing NaCl is generated by pressure through the separation filter. Here, water is sent at a pressure of 0.1 to 1.0 MPa from the pipe R-3 connected to the ultrapure water equipment W-1 through the high-pressure liquid feed pump TP-1 (dissolved oxygen concentration: less than 1mg-O/L, conductivity : less than 1 μS/cm), repeat the liquid-passing operation, and obtain the refined SnS ₂ aggregate (E) with low NaCl content in the separation membrane 2-a. Here, water is sent from the pipe R-4 connected to the ultrapure water device W-1 by the decompression of the vacuum pump V-2 (dissolved oxygen concentration: less than 1 mg-O/L, electrical conductivity: less than 1 μS/cm) , dissolve Na ₂ S·9H ₂ O. Through this operation, a 12 wt % Na ₂ S aqueous solution (F) was prepared by stirring with deoxygenated water in a deoxygenated atmosphere. For E in the separation membrane, send liquid F until SnS ₂ : Na ₂ S = 1:2 (molar ratio), repeat liquid sending-recovery through the circulation line between 2-a and 3-a, and continue this operation until separation E in the membrane 2-a was completely dissolved, and a 15 to 20 wt% Na ₄ SnS ₄ aqueous solution (G) was prepared as a first solution. The G liquid is sent to the airtight container 3-b which is in a vacuum state (-0.1MPa or less) in advance, and is connected with the ion exchange resin tower 4-a.

(Preparation of Li-type cation exchange resin)

In the closed type ion exchange resin column 4-a filled with H-type cation exchange resin, the prepared 1mol/L LiOH aqueous solution (dissolved oxygen concentration of used solvent water: lower than 1mg-O/L, electrical conductivity: low At 1 μS/cm), pass the solution under the conditions of SV=4h ^-1 , BV=6L/LR and carry out ion exchange. Then, under the conditions of SV=4h ^-1 and BV=1L/LR, water (dissolved oxygen concentration: lower than 1mg-O/L, electrical conductivity: lower than 1μS/cm) was passed through to squeeze out the residual solution. Finally, under the conditions of SV=10h ^-1 , BV=10L/LR, wash with water (dissolved oxygen concentration: less than 1mg-O/L, conductivity: less than 1μS/cm) to prepare Li-type cation exchange resin. At this time, water (dissolved oxygen concentration: less than 1 mg-O/L, conductivity: less than 1 μS/cm) is delivered from R-5 to the ion exchange tower 4-a through the liquid feed pump TP-3 to make it Always keep it full of water to prevent air from being mixed in.

(ion exchange process)

Water (dissolved oxygen concentration: lower than 1 mg-O/L, electrical conductivity: lower than 1 μS/cm) is passed through the liquid feed pump TP-3, and is passed through the pipeline R-5 to the ion exchange resin of the Li-type cation exchange resin. Exchange resin column 4-a. Afterwards, the Na ₄ SnS ₄ aqueous solution (G) is passed through the liquid feed pump TP-4 under the conditions of SV=1h ⁻¹ and BV=0.6L/LR for ion exchange. Then, under the conditions of SV=1h ^-1 , BV=2L/LR, water (dissolved oxygen concentration: lower than 1mg-O/L, electrical conductivity lower than 1μS/cm) was squeezed out of the residual solution, and the The Li ₄ SnS ₄ aqueous solution (H) as the second solution is recovered in the vacuum container 4-b (-0.1 MPa or less) connected to the ion exchange resin tower 4-a.

(drying process)

Dry and granulate the Li ₄ SnS ₄ aqueous solution (H) using a closed spray dryer (trade name: GAS-410/GB210, manufactured by YAMATO Science) replaced by N ₂ gas. It was preliminarily dried in an atmosphere, and then dried under reduced pressure while stirring at 240° C. to obtain Li ₄ SnS ₄ powder (I).

A disc-shaped test piece with a radius of 12 mm and a height of 0.6 mm was made by pressing I, and the ionic conductivity was measured at a set temperature (25°C, 50°C, 90°C) by the AC impedance method. The results are shown in Table 1.

[Example 2]

As the water used in the preparation of the first solution and the ion exchange process, except for using non-deoxygenated water (dissolved oxygen concentration: 8mg-O/L) and not using 1-a, 1-b, 2-a, 3- a, 3-b, 4-a, and 4-b were subjected to vacuum or gas replacement, and Li ₄ SnS ₄ powder (I) was prepared in the same manner as in Example 1. For the prepared I, the ion conductivity was measured using the same method as in Example 1. The results are shown in Table 1.

[Example 3]

As the water used in the preparation of the first solution and the ion exchange process, except for using non-deoxygenated water (dissolved oxygen concentration: 8 mg-O/L), 1-a, 1-b, 2-a, 3- a, 3-b, 4-a, 4-b carry out vacuum or gas replacement, and after preparing the Li-type cation exchange resin, take it out from the ion exchange resin tower 4-a and put it back into the ion exchange resin after contacting with air for 24 hours Li ₄ SnS 4 powder (I) was prepared by the same method as in Example 1 except that the ion exchange step was performed in column ₄ -a. For the prepared I, the ion conductivity was measured using the same method as in Example 1. The results are shown in Table 1.

[Comparative example 1]

Comparative example is carried out according to the method of JP 2019-102355 embodiment.

(Preparation of the first solution)

Na ₂ S·9H ₂ O was dissolved in water (dissolved oxygen concentration: 8 mg-O/L) to prepare a 12 wt% Na ₂ S aqueous solution (A). Next, SnCl ₄ ·5H ₂ O was dissolved in water (dissolved oxygen concentration: 8 mg-O/L) to prepare a 28 wt% SnCl ₄ aqueous solution (B). Stir A while cooling, add a small amount of B and mix until Na ₂ S:SnCl ₄ =2:1 (molar ratio) in the mixed liquid, so as to obtain 8wt% SnS ₂ dispersion (C) containing NaCl impurity. C was put into the centrifuge tube, and the centrifuge (trade name: Suprema21, manufactured by TOMY Seiko) was rotated at a speed of 3000-10000rpm for 5 minutes, and the _SnS2 polymer settled to the bottom of the centrifuge tube. Subsequently, by removing the supernatant (including NaCl), _the SnS aggregate (E) was obtained. After adding water (dissolved oxygen concentration: 8 mg-O/L) to E, it was pulverized using an ultrasonic homogenizer to prepare an 8 wt % SnS ₂ dispersion. The obtained SnS ₂ dispersion was purified repeatedly (five times in total) using the above-mentioned centrifuge to reduce the amount of NaCl to obtain a refined SnS ₂ aggregate (F). Add A to F until SnS ₂ : Na ₂ S = 1:2 (molar ratio) in the mixed liquid, and prepare a 15-20 wt% Na ₄ SnS ₄ aqueous solution (G) as the first solution.

(Preparation of Li-type cation exchange resin)

In the ion exchange resin column filled with H-type cation exchange resin, dissolve LiOH·H ₂ O in water (dissolved oxygen concentration: 8 mg-O/L) to prepare 1 mol/L LiOH aqueous solution at SV=4h ^{- 1.} Under the condition of BV=6L/LR, ion exchange is carried out through liquid. Then, water (dissolved oxygen concentration: 8mg-O/L) was squeezed out of the residual solution under the conditions of SV=1h ^-1 , BV=1L/LR, and then the residual solution was squeezed out at SV=10h ^-1 , BV=10L/LR Under the conditions of liquid washing, the Li-type cation exchange resin was obtained.

(ion exchange process)

In the ion exchange resin column filled with the Li-type cation exchange resin replaced with water (dissolved oxygen concentration: 8 mg-O/L), under the conditions of SV=1h ^-1 and BV=0.6L/LR, the The aqueous Na ₄ SnS ₄ solution (G) was subjected to ion exchange. Then, under the conditions of SV=1h ^-1 and BV=2L/LR, water (dissolved oxygen concentration: 8mg-O/L) was passed through and the residual solution was squeezed out, and recovered from the outlet of the ion exchange resin tower as the second Solution Li ₄ SnS ₄ in water (H).

(drying process)

After the Li ₄ SnS ₄ aqueous solution (H) was concentrated in an evaporator, it was frozen and lyophilized at -40°C for 60 hours, and then dried under reduced pressure at 150°C for 1 hour to prepare Li ₄ SnS ₄ powder (I).

Table 1

As shown in Table 1, the ion conductor (Li ₄ SnS ₄ ) prepared by the method of the example, compared with the ion conductor in the comparative example prepared in the air using non-deoxygenated water described in Patent Document 1, the ion conductivity The rate was increased, the mechanism is not clear. It can be seen from the comparative example of using a solvent with a high dissolved oxygen concentration in the air that oxygen in the reaction atmosphere, carbon dioxide, and oxygen in the solvent are important reasons for hindering the ion conduction of the ion conductor. Will remain or combine with any of the elements that make up the ionic conductor, thereby reducing the ionic conductivity. In addition, comparing Examples 1, 2, and 3, compared with the cation exchange resins used in Examples 1 and 2, the contact time of the cation exchange resin used in Example 3 with oxygen in the air is longer, and the ions of the ion conductor conductivity becomes lower. From the above results, it can be known that in the preparation of ion conductors, the amount of oxygen and carbon dioxide (oxygen and carbon dioxide contained in the preparation atmosphere, solvents used, ion exchange resins) contacted in the preparation process has a great influence on the ion conductivity of the ion conductors obtained. have a great impact.

[Example 4]

An embodiment of the present invention provides a preparation device for an ion conductor, as shown in FIG. Three closed reaction vessels 3-a, a separation membrane unit 2-a, a fourth closed reaction vessel 3-b, a closed ion exchange tower 4-a and a closed recovery vessel 4-b.

Specifically, in this embodiment, the ultrapure water equipment W-1 is used to prepare ultrapure water as a deoxygenated solvent; the first closed reaction vessel 1-a is in fluid communication with the ultrapure water equipment W-1, using The chloride of the element ^M that can form trivalent or tetravalent cations is dissolved by the deoxygenated solvent, and prepared as a solution of the chloride of M; the second closed reaction vessel ¹ -b reacts with the first closed reaction vessel respectively The container 1-a is in fluid communication with the ultrapure water device W-1, and is used to dissolve the sulfide of the element M ¹ through the deoxygenated solvent to obtain a sulfide solution of M ¹ , and combine the solution of the chloride of the M ³ with the The sulfide solution of M ¹ is mixed to prepare the suspension of the sulfide of M ³ and the chloride of M ¹ ; the third closed reaction vessel 3-a is in fluid communication with the ultrapure water equipment W-1, for M ¹ The sulfide is dissolved by the deoxygenated solvent to obtain the solution of the sulfide of ^M1 ; the separation membrane unit 2-a is respectively with the ultrapure water equipment W-1, the second closed reaction vessel 1-b and the third closed reaction The container 3-a is in fluid communication, and is used for solid-liquid separation of the suspension of the sulfide of ^M3 and the chloride of ^M1 , and for preparing the dispersion of the sulfide of ^M3 , and for dispersing the sulfide of ^M3 Liquid is dissolved in the solution of the sulfide of M ¹ , and prepares the 1st solution of the 1st compound containing element M ¹ , element M ³ ; The fourth airtight reaction vessel 3-b is connected with the ultrapure water equipment W-1 respectively It is in fluid communication with the separation membrane unit 2-a, and is used to store the first solution to prevent the deterioration of the first solution; the closed ion exchange tower 4-a is connected with the ultrapure water equipment W-1 and the fourth closed reaction vessel 3 respectively -b is in fluid communication, and is used to exchange the first cation ^M1 in the first solution for the second cation under the action of the cation exchange resin to prepare the second solution; the closed recovery container 4-b is connected to the closed ion exchange tower 4 -a is in fluid communication for drying the second solution to obtain the ionic conductor.

It should be noted that the resin used in this embodiment is a cation exchange resin, and an anion exchange resin can also be used.

Element ^M1 may be an atom or molecule capable of losing electrons to a positively charged monatomic ion or molecular ion. Specifically, monatomic ions include hydrogen ions, lithium ions, sodium ions, potassium ions, rubidium ions, cesium ions, magnesium ions, calcium ions, strontium ions, barium ions, aluminum ions, silver ions, and zinc ions. Molecular ions include ammonium ions, PH ⁴⁺ ions, H ₃ O ⁺ ions, H ₂ F ⁺ ions, mercury ions and cycloheptatrienyl cations, etc. Among them, the element ^M in this embodiment is preferably Na.

The element M ³ that can form trivalent or tetravalent cations can be one or more of Sn, As, Bi, Ge, and Sb, and the element M ³ in this embodiment is preferably Sn.

The ion conductor in this embodiment is preferably Li ₄ SnS ₄ .

The following is an example of using cation exchange resin to prepare Li ₄ SnS ₄ ion conductor:

In the preparation system using this ion conductor, in the process of preparing Li ₄ SnS ₄ ion conductor, SnCl ₄ ·5H ₂ O and Na ₂ S are put into the first closed reaction vessel 1-a and the second closed reaction vessel 1-b respectively, because The first airtight reaction vessel 1-a and the second airtight reaction vessel 1-b are all in fluid communication with ultrapure water equipment W-1, and in the first airtight reaction vessel 1-a, utilize ultrapure water equipment W-1 to prepare Deoxygenated solvent and SnCl ₄ 5H ₂ O can obtain SnCl ₄ solution, in the second closed reaction vessel 1-b, use the deoxygenated solvent and Na ₂ S prepared by ultrapure water equipment W-1 to obtain Na ₂ S solution, and then in In the second closed reaction vessel 1-b, the SnCl solution is stirred and reacted with the Na ₂ S solution to obtain a suspension _of SnS ₂ +NaCl; in the third closed reaction vessel, the deoxygenated solvent prepared by ultrapure water equipment and Na ₂ S to obtain Na ₂ S solution, filter and separate the NaCl aqueous solution in the SnS ₂ +NaCl suspension in the separation membrane unit 2-a to obtain a SnS ₂ dispersion, and then dissolve the SnS ₂ dispersion in Na ₂ S Prepare Na ₄ SnS ₄ solution in the solution, store Na ₄ SnS ₄ solution in the fourth airtight reaction vessel to prevent deterioration, and in the airtight ion exchange tower 4-a, Na ions in the Na ₄ SnS ₄ solution are replaced by Li ions, namely A Li ₄ SnS ₄ solution can be obtained, and finally the Li ₄ SnS ₄ solution can be dried to obtain Li ₄ SnS ₄ solid powder or granules. In the above-mentioned process, it is not only more convenient to use the preparation device, but also Li elements, Sn elements, and S elements are exposed to O in a _shorter time, and reduce the oxygen and carbon dioxide (preparation atmosphere, The amount of solvent, oxygen and carbon dioxide contained in the ion exchange resin) is used. Furthermore, the combination of Li element, Sn element, S element and O element can be suppressed, the purity of Li ₄ SnS ₄ can be improved, and the ion conductivity can be improved.

Specifically, during the preparation process, the first closed reaction vessel 1-a and the second closed reaction vessel 1-b are respectively put into SnCl ₄ .5H ₂ O and Na ₂ S with a molar ratio of 1:2, and the first After the airtight reaction vessel 1-a and the second airtight reaction vessel 1-b are evacuated and replaced with Ar gas (purity 99.99%), 80 ml of deoxygenated solvent ultrapure water prepared by ultrapure water equipment W-1 is injected. Slowly transport the SnCl ₄ solution in the first closed reaction vessel 1-a to the second closed reaction vessel 1-b under pressure by Ar gas, and stir in the second closed reaction vessel 1-b to generate a suspension of SnS ₂ +NaCl ;

The resulting suspension liquid is transported to the closed container separation membrane unit 2-a by Ar gas pressurization and decompression of the separation membrane unit 2-a, and the NaCl separation unit is transported from the ultrapure water device W-1 Wash with deoxygenated ultrapure water to obtain a _SnS2 dispersion. At this point, the separated aqueous NaCl solution was drained off.

Put Na ₂ S with a molar ratio of 2 into the third airtight reaction container 3-a airtight container, and replace it with Ar gas after the inside of the container becomes vacuum, and send 80ml of deoxidized Ultrapure water was stirred to dissolve. Transfer this solution to the 2-a container to dissolve the SnS ₂ dispersion to obtain a Na ₄ SnS ₄ solution.

The Na ₄ SnS ₄ solution was transferred to the fourth closed reaction vessel 3-b previously subjected to Ar gas replacement.

Send the Na ₄ SnS ₄ aqueous solution in the fourth closed reaction vessel 3-b into the closed ion exchange tower 4-a, and react with the Li-type ion exchange resin through the closed ion exchange tower 4-a to obtain the Li ₄ SnS ₄ aqueous solution. The Li ₄ SnS ₄ aqueous solution obtained by ion exchange was recycled into the vacuum bag.

The airtight recovery container 4-b was connected to a N ₂ gas displacement type spray dryer (Yamato Scientific GB210+GAS410) and subjected to dry granulation to obtain light yellow Li ₄ SnS ₄ powder. The median diameter D50 at this time is about 1 μm.

The obtained powder was heated to 80°C to 150°C under an Ar gas flow and dried in stages, and then placed under reduced pressure, then heated and stirred at 240°C for about 10 hours to obtain a Li ₄ SnS ₄ ion conductor.

Therefore, the use of the preparation device for the ion conductor provided in this embodiment can reduce the interference of external factors, make it more convenient to use, and help improve the preparation efficiency and purity of the Li ₄ SnS ₄ ion conductor.

Preferably, in this embodiment, the ultrapure water device W-1 includes an ultrapure water storage component and a deoxygenation filter OF. Specifically, the outlet end of the ultrapure water storage component is connected with a connecting pipeline, and the ultrapure water storage component is respectively connected to the first closed reaction vessel 1-a, the second closed reaction vessel 1-b, and the third closed reaction vessel. The reaction vessel 3-a, the separation membrane unit 2-a, the fourth closed reaction vessel 3-b and the closed ion exchange column 4-a are in fluid communication through the connecting pipeline.

More specifically, the deoxygenation filter OF is sequentially connected to the connecting pipeline at the outlet of the ultrapure water storage part in the flow direction of the deoxygenation solvent.

More specifically, the deoxygenation of the ultrapure water can be realized by disposing the deoxygenation filter OF at the outlet of the ultrapure water storage part, which is beneficial to improve the preparation efficiency of the deoxygenation solvent. In addition, the deoxygenation filter OF is equipped with a vacuum pump V-1.

Preferably, in this embodiment, the connecting pipeline includes a main pipeline and a plurality of connecting branch pipes.

Specifically, in this embodiment, the main pipeline communicates with the ultrapure water storage component, the first closed reaction vessel 1-a, the second closed reaction vessel 1-b, the third closed reaction vessel 3-a , the separation membrane unit 2-a, the fourth closed reaction vessel 3-b and the closed ion exchange tower 4-a are respectively connected to the main pipeline through the corresponding connecting branch pipes.

More specifically, five connecting branch pipes can be set, as shown in Fig. 1 , including branch pipe R-1, branch pipe R-2, branch pipe R-3, branch pipe R-4, and branch pipe R-5.

More specifically, the first closed reaction vessel 1-a, the second closed reaction vessel 1-b, the third closed reaction vessel 3-a, the separation membrane unit 2-a, the fourth closed reaction vessel 3- b and the closed ion exchange tower 4-a are respectively connected to the main pipeline through the corresponding connecting branch pipes, so that the first closed reaction vessel 1-a, the second closed reaction vessel 1-b, and the third closed reaction vessel can be avoided. The reflux of reactants in the container 3-a, the separation membrane unit 2-a, the fourth closed reaction vessel 3-b and the closed ion exchange tower 4-a interferes with the preparation process of Li ₄ SnS ₄ .

Preferably, in this embodiment, the deoxygenation filter OF is equipped with a first filter connected to the main pipeline.

With the above technical solution, since the deoxygenation filter OF is equipped with the first filter connected to the main pipeline, the deoxygenation work can be realized by using the filter, which is more convenient to use.

Preferably, in this embodiment, at least the separation membrane unit 2-a and the connecting branch pipe of the closed ion exchange column 4-a are provided with a pressure pump TP-3.

Adopting the above-mentioned technical scheme, a pressure pump TP-3 is set in the connection branch pipe through the separation membrane unit 2-a and the closed ion exchange tower 4-a, which is beneficial to the fluid flow between each reaction unit and further accelerates the Li ₄ SnS ₄ preparation process.

Preferably, in this embodiment, the first closed reaction vessel 1-a, the second closed reaction vessel 1-b, the third closed reaction vessel 3-a, the separation membrane unit 2-a, the fourth The closed reaction vessels 3-b are each equipped with a stirrer ST.

Using the above-mentioned technical scheme, through the first airtight reaction vessel 1-a, the second airtight reaction vessel 1-b, the third airtight reaction vessel 3-a, the separation membrane unit 2-a, the fourth airtight reaction vessel 3-b is equipped with a stirrer ST, so that the first closed reaction vessel 1-a, the second closed reaction vessel 1-b, the third closed reaction vessel 3-a, the separation membrane unit 2-a, the The reactants in the fourth airtight reaction vessel 3-b are evenly mixed to improve the preparation efficiency.

Preferably, in this embodiment, the airtight recovery container 4-b includes a dryer for drying the Li ₄ SnS ₄ solution to obtain Li ₄ SnS ₄ powder.

Preferably, in this embodiment, the airtight recovery container 4-b also includes a heating component and a storage component; the heating component is used to heat the Li ₄ SnS ₄ powder to obtain the Li ₄ SnS ₄ ion conductor; the storage component is a vacuum structure for storage of this Li ₄ SnS ₄ ionic conductor.

Specifically, the Li ₄ SnS ₄ ion conductor can be prevented from being oxidized by setting the storage component as a vacuum structure to store the Li ₄ SnS ₄ ion conductor.

More specifically, in this embodiment, the storage component is set as a vacuum bag.

In this embodiment, the first closed reaction vessel 1-a, the second closed reaction vessel 1-b, the third closed reaction vessel 3-a, the separation membrane unit 2-a, and the fourth closed reaction vessel 3-b can all be Make it a container.

More specifically, in this embodiment, the first closed reaction vessel 1-a, the second closed reaction vessel 1-b, the third closed reaction vessel 3-a, the separation membrane unit 2-a, the fourth closed reaction vessel 3-b all carry out the vacuuming process, and then inject the ultrapure water prepared by the ultrapure water equipment W-1.

More specifically, in this embodiment, the first closed reaction vessel 1-a, the second closed reaction vessel 1-b, the third closed reaction vessel 3-a, and the separation membrane unit 2-a are all reaction vessels. Four airtight reaction vessels 3-b are storage vessels.

The steps of preparing Li ₄ SnS ₄ ion conductor in the preparation system using the ion conductor are as follows:

Step 1: Preparation of SnS ₂

The user puts 0.01mol of SnCl ₄ ·5H ₂ O into the first closed reaction vessel 1-a, puts 0.02mol of Na ₂ S into the second closed reaction vessel 1-b, and puts the container into the first closed reaction vessel 1-a Vacuum the inside of the second airtight reaction vessel 1-b and replace it with Ar gas (purity: 99.99%). The ultrapure water is deoxygenated by ultrapure water equipment W-1 to obtain deoxygenated ultrapure water. 80 ml each of the unit deoxygenation solvents were sent to the first closed reaction vessel 1-a and the second closed reaction vessel 1-b, and stirred to dissolve SnCl ₄ and Na ₂ S. Slowly transport the _SnCl solution in the first closed reaction vessel 1-a of the vessel to the second closed reaction vessel 1-b by pressurizing Ar gas, and stir in the second closed reaction vessel 1-b to generate SnS ₂ +NaCl of turbid liquid. The suspension liquid of SnS ₂ +NaCl is transported to the closed vessel separation membrane unit 2-a by Ar gas pressurization and the decompression of the vessel separation membrane unit 2-a for liquid phase synthesis reaction. A second filter is arranged in the closed container separation membrane unit 2-a, and after the reaction is completed, the reaction product in the second filter is cleaned with a deoxygenated solvent to obtain a dispersion of SnS ₂ . The aqueous NaCl solution separated from the filter was removed.

Regarding the separation process of NaCl, the filter washing method of the present invention, through such adjustment, reduces the amount of proportion deviation and residual chloride, can suppress the change of chlorine content of Li and Sn, and after ion exchange into Li ₄ SnS ₄ Residual Cl ⁻ .

The second step: preparation of Na ₄ SnS ₄ solution

0.02 mol of Na ₂ S was put into the reaction vessel 3-a, and the reaction vessel 3-a was evacuated and replaced with Ar gas. 80 ml of the deoxygenated solvent was sent from the ultrapure water device W-1 to the reaction vessel 3-a, and stirred and dissolved. Transfer the solution to the separation membrane unit 2-a container, dissolve the SnS ₂ dispersion to obtain a Na ₄ SnS ₄ solution, and transfer the fully dissolved Na ₄ SnS ₄ solution to the storage container 3-b that has been replaced by Ar gas in advance middle.

The third step: preparation of Li ₄ SnS ₄ aqueous solution

The Na ₄ SnS ₄ aqueous solution in the container storage container 3-b is sent to the closed ion exchange tower 4-a, and the Li ₄ SnS ₄ aqueous solution is obtained by ion exchange reaction with Li-type ion exchange resin. The Li ₄ SnS ₄ aqueous solution obtained by ion exchange was recycled into the vacuum bag.

Step 4: Preparation of Li ₄ SnS ₄ Powder

The vacuum bag was connected to a N ₂ gas displacement type spray dryer (manufactured by Yamato Science, GB210+GAS410) for dry granulation to obtain light yellow Li ₄ SnS ₄ powder. The median diameter D50 at this time was 1 μm.

Step 5: Preparation of Li ₄ SnS ₄ Ionic Conductor

The obtained Li ₄ SnS ₄ powder is heated to 80°C to 150°C under an Ar gas flow and dried in stages, and then placed in a reduced pressure state, then heated at 240°C with stirring for about 10 hours to obtain Li ₄ SnS ₄ ionic conductors.

In the prior art JP 2019-102355, the ion-exchanged Li ₄ SnS ₄ solution is concentrated, freeze-dried and powdered, but this process usually takes about 60 hours. In the present invention, the solution after ion exchange is directly spray-dried and granulated under _N2 gas atmosphere, so that the time is shortened to about 2 hours.

When the preparation system using this ion conductor is used to prepare the Li ₄ SnS ₄ ion conductor, it is also possible to: only deoxidize the ultrapure water, do not replace the container with an inert gas, and operate in the same manner as the above examples to obtain Li _{4 SnS4} ionic conductor.

It is also possible that only the container is replaced with inert gas, and the ultrapure water is not deoxidized, and the rest is performed in the same manner as in the above-mentioned embodiment to prepare the Li ₄ SnS ₄ ion conductor.

Although the present invention has been illustrated and described with reference to some preferred embodiments of the present invention, those skilled in the art should understand that the above content is a further detailed description of the present invention in conjunction with specific embodiments, and cannot be deemed Embodiments of the present invention are limited only by these descriptions. Without departing from the spirit and scope of the present invention, those skilled in the art may make various changes in form and details, including making some simple deduction or replacement, which also belong to a part of the present invention.

Claims (10)

1. A method for producing an ion conductor, characterized in that a 1 st compound having a 1 st cation and a 1 st anion as a counter ion thereof is dissolved in a solvent to form a 1 st solution, at least a part of the 1 st cation or the 1 st anion in the 1 st compound is exchanged with a2 nd cation or a2 nd anion by an ion exchange method to obtain a2 nd compound, the 2 nd compound is dissolved in the solvent to obtain a2 nd solution containing an ion conductor, the solvent contains a deoxygenated solvent, and the production of the ion conductor is carried out without contacting air.

2. The method for producing an ion conductor according to claim 1, wherein the solvent contains water.

3. The method of claim 2, wherein the solvent has a dissolved oxygen concentration of less than 8mg-O/L.

4. The method for producing an ion conductor according to any one of claims 1 to 3, further comprising a drying step of removing the solvent from the 2 nd solution to obtain an ion conductor.

5. The method for producing an ion conductor according to any one of claims 1 to 4, which uses CO containing less than 1000ppm of oxygen ₂ An inert atmosphere in an amount of less than 100 ppm.

6. The ion conductor prepared by the preparation method according to any one of claims 1 to 5, having a median particle diameter D50 of 0.05 to 500 μm.

7. An apparatus for preparing an ionic conductor, comprising:

an ultrapure water apparatus for preparing ultrapure water as a deoxygenation solvent;

a first closed reaction vessel in fluid communication with the ultrapure water device for carrying out SnCl ₄ ·5H ₂ O is dissolved by the deoxidizing solvent, and SnCl is prepared ₄ A solution;

a second closed reaction vessel, which is respectively in fluid communication with the first closed reaction vessel and the ultrapure water device and is used for introducing Na ₂ S is dissolved by the deoxygenated solvent to obtain Na ₂ S solution, and adding the SnCl ₄ Solution with said Na ₂ S solution mixing preparation SnS ₂ Suspension of + NaCl;

a third closed reaction vessel in fluid communication with the ultrapure water device for reacting Na ₂ S is dissolved by the deoxidizing solvent to obtain Na ₂ S solution;

a separation membrane unit in fluid communication with the ultrapure water device, the second closed reaction vessel and the third closed reaction vessel, respectively, for pairing SnS ₂ Filtering and separating NaCl suspensionDissociating and preparing SnS ₂ A dispersion liquid for adding Na in the third closed reaction vessel ₂ Introducing S solution into the reactor and mixing with SnS ₂ Reaction to prepare Na ₄ SnS ₄ Taking the solution as a 1 st solution;

a fourth closed reaction vessel, which is respectively in fluid communication with the ultrapure water device and the separation membrane unit, and is used for storing the 1 st solution and preventing the 1 st solution from deteriorating;

a closed ion exchange column in fluid communication with the ultrapure water device and the fourth closed reaction vessel, respectively, for reacting Na ₄ SnS ₄ Na ions in the solution are exchanged for Li ions, and Li is prepared under the action of Li type ion exchange resin ₄ SnS ₄ The solution is used as a2 nd solution;

a closed recovery vessel in fluid communication with the closed ion exchange column for Li-rejection ₄ SnS ₄ Li obtained after drying of the solution ₄ SnS ₄ Solid powders or granules are stored.

8. The apparatus for preparing an ionic conductor according to claim 7, wherein the ultrapure water device comprises an ultrapure water storage section and a deoxidation filter; wherein,

the outlet end of the ultrapure water storage component is connected with a connecting pipeline, and the ultrapure water storage component is respectively in fluid communication with the first closed reaction vessel, the second closed reaction vessel, the third closed reaction vessel, the separation membrane unit, the fourth closed reaction vessel and the closed ion exchange tower through the connecting pipeline;

the deoxidation filter is connected to the connecting pipeline at the outlet of the ultrapure water storage component.

9. The apparatus for preparing an ionic conductor according to claim 8, further comprising an inert gas tank; wherein,

the first closed reaction container, the second closed reaction container, the third closed reaction container, the separation membrane unit and the fourth closed reaction container are respectively connected with the inert gas tank through pipelines.

10. The apparatus for preparing an ionic conductor according to claim 8, further comprising a vacuum pump,

the first closed reaction vessel, the second closed reaction vessel, the third closed reaction vessel, the separation membrane unit and the fourth closed reaction vessel are respectively connected with the vacuum pump pipeline.

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