KR20190074587A - Method for Preparing Solid Electrolyte, Solid Electrolyte Prepared by Using the Same, and All Solid Battery Comprising the Solid Electrolyte - Google Patents

Abstract

The present invention relates to a solid electrolyte producing method which includes the following steps of: mixing and stirring first lithium sulfide and the sulfide of metal M in a first organic solvent to prepare a first suspension; mixing and stirring second lithium sulfide and LiX in a second organic solvent to prepare a second suspension; and producing a sulfide-based compound represented by chemical formula 1, Li_aM_bS_cX_d, by mixing the first suspension and the second suspension and then drying the mixture in a vacuum state. In chemical formula 1, M is one or more selected from a group consisting of Al, Si, P, Ga, Ge, As, In, Sn, and Sb, X is one selected from a group consisting of F, Cl, Br, and I, and following conditions, 1 <= a <= 7, 0 <= b <= 3, 4 <= c <= 7, and 0 <= d <= 1 are satisfied. According to the present invention, both superior battery characteristics and excellent manufacturing processes are possible.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a solid electrolyte, a solid electrolyte produced using the solid electrolyte,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte production method, a solid electrolyte produced using the solid electrolyte, and a whole solid battery including the solid electrolyte.

Lithium secondary batteries are widely used as power sources for mobile electronic devices including mobile phones, and their applications are expanding as demand for large-sized devices such as electric vehicles increases.

On the other hand, since the lithium secondary battery uses a liquid electrolyte in which a lithium salt is dissolved in an organic solvent, there is a potential risk of ignition and explosion due to electrolyte decomposition reaction as well as electrolyte leakage. In fact, there is an urgent need to overcome these problems, as the explosion of products using them is continuously occurring.

All solid electrolytes are replaced with solid electrolytes, which are advantageous from the standpoint of safety because the components of all cells, such as electrodes and electrolytes, are solid. In addition, since lithium metal or Li alloy can be used as a negative electrode material, it is known that it is advantageous from the viewpoint of battery performance such as high energy density, high output and long life.

It is important to develop a solid electrolyte having a high lithium ion conductivity in order to exhibit the performance of the all-solid battery, and sulfide compounds such as Li ₁₀ GeP ₂ S ₁₂ , Li ₆ PS ₅ Cl, and Li ₂ SP ₂ S ₅ are widely used have.

Such a sulfide-based solid electrolyte has been produced by a conventional melting method or a solid phase method.

As one example, the melting method uses a method of quenching a melt obtained by melting starting materials such as L ₂ S and P ₂ S ₅ . However, the composition of the composite is not stable due to the pyrolysis gas generated in the melting process, and it is difficult to control the size of the particles. Therefore, when the solid electrolyte is used as a solid electrolyte, a separate pulverizing step is required.

The solid phase method mainly uses mechanical milling. For example, the starting material and the ball mill are placed in the reactor, and the starting material is dispersed and mixed with strong vibration, and then heat treatment is performed. However, it is difficult to enlarge the high-energy milling machine, and thus it is difficult to uniformly disperse and amorphize the starting materials and mass synthesis is not easy.

In order to solve this problem, a wet process for synthesizing a sulfide-based solid electrolyte by stirring the starting materials in an organic solvent such as THF has been proposed. However, since the purity of the compound is low and the ionic conductivity is low, There is an inadequate problem.

Accordingly, there is a high need for a method for producing a solid electrolyte having a high synthesis yield and purity while exhibiting a high lithium ion conductivity.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

Specifically, it is an object of the present invention to provide a method for producing a solid electrolyte having high lithium ion conductivity and excellent synthesis yield and purity, and a solid electrolyte prepared therefrom.

Another object of the present invention is to provide a pre-solid battery using the solid electrolyte and having excellent cell characteristics and excellent processability.

According to the present invention,

(A) mixing and stirring the first lithium sulfide and the sulfide of the metal M in a first organic solvent to prepare a first suspension;

(B) mixing and stirring the second lithium sulfide and LiX in a second organic solvent to prepare a second suspension; And

(C) mixing the first suspension and the second suspension, followed by vacuum drying, to prepare a sulfide compound represented by the following formula (1);

And a solid electrolyte.

Li_aM_bS_cX_d (One)

  In this formula,

M is one or more selected from the group consisting of Al, Si, P, Ga, Ge, As, In, Sn and Sb;

X is one selected from the group consisting of F, Cl, Br, and I; And

1? A? 7, 0 <b? 3, 4? C? 7, and 0 <d?

The first lithium sulfide may be one selected from the group consisting of Li ₂ S, Li ₂ S ₂ , Li ₂ S ₄ , and Li ₂ S ₆ .

The sulfide of the first lithium sulfide and the metal M may be 20:80 to 60:40 by weight.

The first organic solvent may be an aprotic polarity solvent for daily use.

The aprotic polar solvent is preferably selected from the group consisting of tetrahydrofuran (THF), ethyl acetate, acetone, dimethylsulfoxide (DMSO), dimethylformamide (DMF), acetonitrile, dibutyl ether (DBE) and propylene carbonate May be one or more selected from the group.

The first organic solvent may be 60 to 99 wt% based on the total weight of the first suspension.

The mixing agitation of step (a) may be carried out at a rotation speed of 100 to 500 rpm at 10 to 14 hours at 50 to 90 degrees ().

The second lithium sulfide may be one selected from the group consisting of Li ₂ S, Li ₂ S ₂ , Li ₂ S ₄ , and Li ₂ S ₆ .

The second lithium sulfide and LiX, wherein X is one selected from the group consisting of F, Cl, Br, and I, may be from 20:80 to 60:40 by weight.

The second organic solvent may be used for positive polarity polarity.

The protonic polar solvent may be at least one selected from the group consisting of ethanol, isopropanol, n-butanol, acetic acid, and nitromethane.

The second organic solvent may be 60 to 99 wt% based on the total weight of the second suspension.

The mixing agitation in the step (b) may be carried out at a rotation speed of 100 to 500 rpm at 10 to 14 hours at 50 to 90 degrees ().

In the step (c), the first suspension and the second suspension may be mixed in a weight ratio of 30:70 to 70:30.

Vacuum drying in step (c) can be performed at 100 to 250 degrees Celsius.

According to the present invention,

(D) subjecting the compound prepared in step (c) to a heat treatment at 400 to 700 degrees Celsius;

. &Lt; / RTI &gt;

Further, the present invention provides a solid electrolyte produced using the above-mentioned production method.

The ionic conductivity of the solid electrolyte may be 1 * 10 ^-5 to 5 * 10 ^-3 S / cm at 25 degrees ().

The present invention also provides a pre-solid battery comprising the solid electrolyte.

The present invention provides a method of producing a solid electrolyte comprising stirring the starting materials in two kinds of predetermined organic solvents, respectively, and drying the mixture in a vacuum, so that it is possible to control the physical properties of the particles easily and to obtain sulfides A solid electrolyte containing a base compound can be provided. Since the production method scales up the volume of the reactor to easily increase the amount of the starting material and the organic solvent, it can provide a large amount of solid electrolyte exhibiting excellent lithium ion conductivity. Therefore, all solid-state batteries using the same have high lifetime characteristics and energy density, and can be mass-produced in large quantities.

1 is a graph showing the results of an X-ray diffraction pattern of a solid electrolyte prepared according to Example 2. Fig.

Method of manufacturing solid electrolyte

Solid electrolytes using sulfide-based compounds in general have been produced through a melting process, a solid phase process, a wet process, or the like, as described above.

Particularly, in the case of the solid-phase method, scale-up is difficult because a special device such as a high-energy milling machine is used, and energy and time are consumed in operation of the apparatus, leading to cost increase. There was a problem.

Further, in the case of the wet process in which the starting materials are heated in an organic solvent, stirred, and then dried, it is difficult to control the physical properties of the resultant composition, resulting in low synthesis yield and ionic conductivity, which is problematic in application as a solid electrolyte.

Therefore, the production method according to the present invention includes a step of mixing and starting the respective starting materials in two kinds of specific organic solvents, followed by mixing and vacuum drying to synthesize a sulfide-based compound. Therefore, A solid electrolyte showing conductivity can be provided. This is because the difference in solubility of the starting material occurs depending on the organic solvent, and the difference in the reaction rate affects the purity of the synthesized material.

Specifically,

(A) mixing and stirring the first lithium sulfide and the sulfide of the metal M in a first organic solvent to prepare a first suspension;

(B) mixing and stirring the second lithium sulfide and LiX in a second organic solvent to prepare a second suspension; And

(C) mixing the first suspension and the second suspension, followed by vacuum drying, to prepare a sulfide compound represented by the following formula (1);

The present invention also provides a method for producing a solid electrolyte.

Li_aM_bS_cX_d (One)

  In this formula,

M is one or more selected from the group consisting of Al, Si, P, Ga, Ge, As, In, Sn and Sb;

X is one selected from the group consisting of F, Cl, Br, and I; And

1? A? 7, 0 <b? 3, 4? C? 7, and 0 <d?

The first lithium sulfide of step (a) is a lithium precursor of the compound of formula (1), for example, one selected from the group consisting of Li ₂ S, Li ₂ S ₂ , Li ₂ S ₄ and Li ₂ S ₆ And may be Li ₂ S in detail.

The sulfides of the metal M can be represented by M _{a '} S _b' , and a 'and b' can have appropriate values depending on the oxidation number of M, for example, when the metal M is P, P ₂ S ₅ .

The weight ratio of the first lithium sulfide and the metal sulfide may be appropriately adjusted according to the composition ratio of the compound of formula (1), for example, 20: 80 to 60:40 by weight.

If the content of the first lithium sulfide is excessively large or the content of the sulfide of the metal M is excessively small outside the above range, it is difficult for the composite to maintain a proper crystal structure and to secure a sufficient ion conductivity, and if the content of the first lithium sulfide is excessively low Or the content of the sulfide of the metal M is excessively large, the metal M acts as an impurity rather than the metal M, so that the ion conductivity may drop sharply. Specifically, it may be 30:70 to 50:50.

The first organic solvent is not particularly limited as long as the starting material can be dissolved and dispersed well. For example, in the case of an aprotic polar solvent, it is confirmed that the sulfide of the metal M is uniformly dispersed.

Specific examples of the aprotic polar solvent include tetrahydrofuran (THF), ethyl acetate, acetone, dimethylsulfoxide (DMSO), dimethylformamide (DMF), acetonitrile, dibutyl ether (DBE) and propylene carbonate (PC), and more particularly, may be tetrahydrofuran (THF).

The first organic solvent may be 60 to 99 wt% based on the total weight of the first suspension. If the amount of the first organic solvent is excessively large, it is difficult to sufficiently remove the first organic solvent in the subsequent drying step, which may act as an impurity in the composition. If the amount is too small, the second lithium sulfide and the sulfide of the metal M are uniformly dispersed It is difficult and not desirable. And more specifically from 70 to 99% by weight, based on the total weight of the first suspension.

In some cases, the nonpolar organic solvent may be further mixed in an amount of 10 to 20% by weight based on the total weight of the first suspension. The apolar organic solvent may be, for example, but not limited to, heptane, toluene, or a mixture thereof.

The first lithium sulfide and the sulfide of the metal M may be mixed and stirred in a first organic solvent to prepare a first suspension containing an amorphous sulfide.

The mixing and stirring may be performed using, for example, a magnetic stirrer, a spray drier, an ultrasonic disperser or the like, and more specifically, a magnetic stirrer to uniformly mix the samples.

The higher the rotation speed, the faster the compound production rate. The longer the rotation time, the higher the conversion rate of the compound to the starting material. For example, the rotation speed is from 100 to 500 rpm at 50 to 90 degrees &Lt; / RTI &gt;

If the rotation speed or the rotation time is excessively slower than the above range, the particles may not be uniformly dispersed in the suspension. If the rotation speed or the rotation time is excessively high, energy transferred to the particles is excessively high, I do not. More specifically, it can be carried out at 60 to 80 degrees Celsius (rpm) at 200 to 400 rpm for 11 to 13 hours.

In the present invention, the second lithium sulfide of step (b) is another lithium precursor of the compound of formula (1), for example Li ₂ S, Li ₂ S ₂ , Li ₂ S ₄ and Li ₂ S ₆ And may be Li ₂ S in detail.

The above LiX (wherein X is one selected from the group consisting of F, Cl, Br, and I; hereinafter referred to as LiX) may be specifically LiCl or LiBr.

The weight ratio of the second lithium sulfide and LiX can be appropriately controlled according to the composition ratio of the compound of the formula (1) to be synthesized, and can be, for example, 20:80 to 60:40 by weight.

If the content of the second lithium sulfide is excessively small or the content of LiX is excessively small outside the above range, the composition maintains a proper crystal structure and thus it is difficult to secure a sufficient ion conductivity. When the content of the second lithium sulfide is excessively small, If the content is excessively large, the ionic conductivity acts as an impurity rather than a sharp drop, which is undesirable. Specifically, it may be 30:70 to 50:50.

The second organic solvent is not particularly limited as long as the starting material can be dissolved and dispersed well. For example, LiX is uniformly dispersed in the case of a protic polar solvent.

The protonic polar solvent may be at least one selected from the group consisting of ethanol, isopropanol, and n-butanol, acetic acid, and nitromethane, and in particular, ethanol. In some cases, an anionic polar protic solvent may be used to prevent side reactions.

The second organic solvent may be 60 to 99 wt% based on the total weight of the second suspension. If the amount of the second organic solvent is excessively large, it may be difficult to sufficiently remove the second organic solvent in the subsequent drying process, which may act as an impurity in the composition. If the second lithium sulfide and LiX are too small, not. In particular from 70 to 99% by weight, based on the total weight of the second suspension.

In some cases, the nonpolar organic solvent may be further mixed in an amount of 10 to 20% by weight based on the total weight of the second suspension. The apolar organic solvent may be, for example, but not limited to, heptane, toluene, or a mixture thereof.

The second lithium sulfide and LiX may be mixed and stirred in a second organic solvent to prepare a second suspension containing an amorphous sulfide.

The mixing and stirring may be performed using, for example, a magnetic stirrer, a spray drier, an ultrasonic disperser or the like, and more specifically, a magnetic stirrer to uniformly mix the samples.

The higher the rotation speed, the faster the compound production rate. The longer the rotation time, the higher the conversion rate of the compound to the starting material. For example, the rotation speed is from 100 to 500 rpm at 50 to 90 degrees &Lt; / RTI &gt;

If the rotation speed or the rotation time is excessively slower than the above range, the particles may not be uniformly dispersed in the suspension. If the rotation speed or the rotation time is excessively high, energy transferred to the particles is excessively high, I do not. More specifically, it can be carried out at 60 to 80 degrees Celsius (rpm) at 200 to 400 rpm for 11 to 13 hours.

In the present invention, the first suspension and the second suspension are mixed in a weight ratio of 30:70 to 70:30, followed by vacuum drying to remove the organic solvent to obtain an amorphous compound.

The weight ratio of the first suspension and the second suspension may be appropriately adjusted according to the composition ratio of the compound of the formula (1) to be synthesized, specifically, from 40:60 to 60:40.

The vacuum drying can be carried out at a temperature of 100 ° C to 250 ° C (in a special container with a bath of silicone oil). If the drying temperature is too high, the transition to the phase having low ionic conductivity may occur. If the drying temperature is too low, the organic solvent can not be sufficiently removed, and the ionic conductivity of the solid electrolyte Which is undesirable. Thus, in detail, vacuum drying can be performed at 120 to 180 degrees.

In this drying process, harmful substances such as hydrogen sulfide are likely to be generated due to moisture in the air, so that the drying can be performed in a vacuum condition, for example, a glove box or a dry room having a degree of vacuum of less than 0.1 mmHg, so as not to come into contact with the atmosphere.

On the other hand,

(D) heat-treating the compound prepared in the step (c) at a temperature of 400 ° C to 700 ° C to improve the crystallinity of the sulfide compound.

When the temperature is less than 400 ° C, the crystallization may not proceed sufficiently due to an excessively low temperature. When the temperature exceeds 700 ° C, particles of the sulfide-based compound become too large to produce particles having a uniform size, It is not preferable. Specifically, it may be 500 to 600 degrees.

During the heat treatment, harmful substances such as hydrogen sulfide are likely to be generated due to moisture in the air, so that it may be performed in a vacuum condition such as a glove box or a dry room having a degree of vacuum of less than 0.1 mmHg so as not to contact with the atmosphere.

Solid electrolyte

The present invention provides a solid electrolyte comprising a sulfide-based compound represented by the formula (1), which is produced using the above-mentioned production method.

The sulfide-based compound may specifically include a crystalline phase of an argyrodite type crystal structure. The aziridate type crystal structure is well known in the art, and a detailed description thereof will be omitted.

The ionic conductivity of the solid electrolyte containing the sulfide compound may be 1 * 10 ^-5 to 5 * 10 ^-3 S / cm at room temperature (25). It can be confirmed that the solid electrolyte prepared according to the present invention exhibits excellent lithium ion conductivity with sufficient ion conductivity for practical use of solid electrolytes for all solid electrolytes.

Such a sulfide-based compound can be manufactured to have an average particle size of several nanometers to several thousands of micrometers, and its form is not particularly limited. When the nano-sized particle size is used, the contact area with the electrode active material is increased so that the lithium ion transfer path is enlarged, which is advantageous for charging and discharging. Specifically, the average particle size can be within the range of 0.001 micrometer to 50 micrometer.

All solid-state cells

The present invention provides a pre-solid battery comprising the solid electrolyte.

As described above, the present invention produces solid electrolytes exhibiting excellent lithium ion conductivity by using two kinds of predetermined organic solvents, and all solid batteries using the same can ensure high lifetime characteristics and energy densities , It is easy to scale up, mass production is possible, and thus the manufacturing process is excellent.

Specifically, the pre-solid battery includes a positive electrode, a negative electrode, and a solid electrolyte disposed between the positive electrode and the negative electrode.

Hereinafter, the entire solid-state battery of the present invention will be described for each structure.

The positive electrode may be formed by applying a positive electrode mixture containing a positive electrode active material to a current collector, and the positive electrode mixture may further include a binder and a conductive material, if necessary.

The cathode active material may include, for example, LiNi _0.8-x Co _0.2 Al _x O ₂ , LiCo _x Mn _y O ₂ , LiNi _x Co _y O ₂ , LiNi _x Mn _y O ₂ , LiNi _x Co _y Mn _z O ₂ , LiCoO ₂ , Lithium metal oxides (0 <x <1, 0 <y <1) such as LiNiO ₂ , LiMnO ₂ , LiFePO ₄ , LiCoPO ₄ , LiMnPO ₄ and Li ₄ Ti ₅ O ₁₂ ; Cu ₂ Mo ₆ S ₈ , chalcogenides such as FeS, CoS and MiS, oxides, sulfides or halides of scandium, ruthenium, titanium, vanadium, molybdenum, chromium, manganese, iron, cobalt, nickel, And more specifically, LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , TiS ₂ , ZrS ₂ , RuO ₂ , Co ₃ O ₄ , Mo ₆ S ₈ , and V ₂ O ₅ may be used, but the present invention is not limited thereto.

The shape of the cathode active material is not particularly limited and may be a particle shape, for example, a spherical shape, an elliptical shape, a rectangular parallelepiped shape, or the like. The average particle diameter of the cathode active material may be within the range of 1 to 50 占 퐉, but is not limited thereto. The average particle diameter of the cathode active material can be obtained, for example, by measuring the particle size of the active material observed by a scanning electron microscope and calculating the average value thereof.

The binder is not particularly limited, and fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) may be used, but the present invention is not limited thereto.

The content of the binder is not particularly limited as long as it can fix the cathode active material, and may be in the range of 0 to 10 wt% with respect to the total amount of the cathode mixture.

The conductive material is not particularly limited as long as it can improve the conductivity of the anode, and examples thereof include nickel powder, cobalt oxide, titanium oxide, and carbon. Specifically, the carbon may be any one selected from the group consisting of Ketjen black, acetylene black, furnace black, graphite, carbon fiber, and fullerene, or one or more thereof.

The content of the conductive material may be selected in consideration of other battery conditions, such as the type of conductive material, and may be, for example, in the range of 1 to 10% by weight based on the entire anode.

The thickness of the positive electrode material mixture layer may be, for example, 0.1 micrometer to 1000 micrometer.

The positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, Nickel, titanium, silver, or the like may be used. In addition, various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric having fine irregularities on the surface may be used.

The negative electrode of the pre-solid battery may be a lithium metal or a lithium alloy alone or may be coated with a negative electrode mixture containing a negative electrode active material on the negative electrode collector. The negative electrode material mixture may further include a binder and a conductive material, if necessary.

The negative electrode active material may be at least one selected from the group consisting of lithium metal, a lithium alloy, a lithium metal composite oxide, a lithium-containing titanium composite oxide (LTO), and combinations thereof. The lithium alloy may be an alloy of lithium and at least one metal selected from Na, K, Rb, Cs, In, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al and Sn. In addition, lithium metal composite oxide is lithium and Si, Sn, Zn, Mg, Cd, Ce, Ni, and is one of a metal (Me) oxide (MeO _x) selected from the group consisting of Fe, for example in Li _x Fe ₂ O ₃ (0 < x? 1) or Li _x WO ₂ (0 <x? 1). In addition, Sn _x Me _1-x Me _y O _z (Me: Mn, Fe, Pb, Ge; Me ': Al, B, P, Si, Group 1, Group 2, Group 3 elements of halogen, <x? 1; 1? y? 3; 1? z? 8); _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO2 2, Bi 2 O 3, Bi 2 O 4 , and Bi ₂ O ₅ and the like, and carbonaceous materials such as crystalline carbon, amorphous carbon or carbon composite may be used alone or in combination of two or more.

In this case, the anode current collector is not particularly limited as long as it has electrical conductivity without causing any chemical change in the entire solid battery. For example, the cathode current collector may be formed on the surface of copper, stainless steel, aluminum, nickel, titanium, Carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. The negative electrode current collector may be formed in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven fabric, and the like having fine irregularities on its surface.

The production of all the solid batteries having the above-mentioned constitution is not particularly limited in the present invention, and can be produced by a known method.

Specifically, a solid electrolyte according to the present invention is disposed between an anode and a cathode, and the cell is assembled by compression molding.

Specifically, the solid electrolyte may be in the form of a solid electrolyte sheet, and may be formed by mixing a solid electrolyte with a binder or by press molding, or by dispersing the solid electrolyte in a solvent to form a slurry by a doctor blade or a spin coat Can be manufactured.

The assembled cell is installed in the casing and then sealed by heat compression or the like. Laminate packs made of aluminum, stainless steel or the like, and cylindrical or square metal containers are very suitable for the exterior material.

The following examples are provided for illustrative purposes only and are not intended to limit the scope of the present invention.

&Lt; Example 1 >

All experiments were performed in a glove box or dryer room that was not exposed to moisture and oxygen.

The first suspension was prepared by adding Li ₂ S and P ₂ S ₅ as starting materials in THF at 38: 62 on a weight basis and stirring at 70 rpm (300 rpm) for 12 hours. Wherein the THF is 95% by weight based on the total weight of the first suspension. In a separate reactor, Li ₂ S and LiBr as starting materials were added to anhydrous ethanol at 35:65 on a weight basis and stirred at 70 rpm (300 rpm) for 12 hours to prepare a second suspension. Wherein the anhydrous ethanol is 95 wt% based on the total weight of the second suspension.

The first suspension and the second suspension obtained in the above process were mixed at a ratio of 42: 58 on a weight basis and placed in a special container with a silicone oil bath, followed by vacuum drying at 150 ° C to obtain a white powder.

&Lt; Example 2 >

The white powder obtained in Example 1 was heat-treated at 550 ° C in a vacuum atmosphere to improve crystallinity.

&Lt; Comparative Example 1 &

The starting materials Li ₂ S, P ₂ S _5, and LiBr was added in anhydrous ethanol (37: 35: 28) on a weight basis and agitated at 70 rpm (300 rpm) for 12 hours. Vacuum drying was carried out at 150 ° C Powder was obtained.

&Lt; Comparative Example 2 &

A yellow powder was obtained in the same manner as in Comparative Example 1, except that THF was used as the solvent.

<Experimental Example 1>

The lithium ion conductivity of the compounds obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was checked by AC impedance measurement in order to confirm the change in lithium ion conductivity. The results are shown in Table 1 below.

Lithium ion conductivity (S / cm) Example 1 1.1 * 10 ^-5 Example 2 3.9 * 10 ^-4 Comparative Example 1 Measurement not possible (exceeding limit) Comparative Example 2 Measurement not possible (exceeding limit)

According to the above Table 1, it can be confirmed that the solid electrolytes of Examples 1 and 2 produced by the production method of the present invention exhibit high lithium ion conductivity. Particularly, after vacuum drying and further heat treatment, It can be confirmed that the lithium ion conductivity of the electrolyte is further increased. This is because the difference in solubility of the starting material occurs depending on the organic solvent, and the difference in the reaction rate thus affects the purity of the synthesized material.

<Experimental Example 2>

The results of X-ray diffraction analysis of the compound obtained in Example 2 are shown in FIG.

Referring to FIG. 1, the compound of Example 2 has a main peak of Li ₆ PS ₅ Br and a content of about 80.4%, which indicates that the solid electrolyte prepared according to the present invention has a high yield and purity.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (19)

(A) mixing and stirring the first lithium sulfide and the sulfide of the metal M in a first organic solvent to prepare a first suspension;
(B) mixing and stirring the second lithium sulfide and LiX in a second organic solvent to prepare a second suspension;
(C) mixing the first suspension and the second suspension, followed by vacuum drying, to prepare a sulfide compound represented by the following formula (1);
The method for producing a solid electrolyte according to claim 1,
Li_aM_bS_cX_d (One)
  In this formula,
M is one or more selected from the group consisting of Al, Si, P, Ga, Ge, As, In, Sn, and Sb;
X is one selected from the group consisting of F, Cl, Br, and I; And
1? A? 7, 0? B? 3, 4? C? 7 and 0? D? The method of claim 1, wherein the first lithium sulfide is one selected from the group consisting of Li ₂ S, Li ₂ S ₂ , Li ₂ S _4, and Li ₂ S ₆ . The method of claim 1, wherein the sulfide of the first lithium sulfide and the metal M is 20:80 to 60:40 by weight. The method for producing a solid electrolyte according to claim 1, wherein the first organic solvent is an aprotic polar solvent. The process of claim 4, wherein the aprotic polar solvent is selected from the group consisting of tetrahydrofuran (THF), ethyl acetate, acetone, dimethylsulfoxide (DMSO), dimethylformamide (DMF), acetonitrile, dibutyl ether And carbonate (PC). The method of claim 1, wherein the first organic solvent is 60 to 99 wt% based on the total weight of the first suspension. The method for producing a solid electrolyte according to claim 1, wherein the mixed agitation in step (A) is carried out at a revolution rate of 100 to 500 rpm at 10 to 14 hours at 50 to 90 degrees. The method of claim 1, wherein the second lithium sulfide is one selected from the group consisting of Li ₂ S, Li ₂ S ₂ , Li ₂ S _4, and Li ₂ S ₆ . The lithium secondary battery according to claim 1, wherein the second lithium sulfide and LiX (wherein X is one selected from the group consisting of F, Cl, Br, and I) is 20:80 to 60:40 by weight A method for producing a solid electrolyte. The method for producing a solid electrolyte according to claim 1, wherein the second organic solvent is a protonic polar solvent. The method for producing a solid electrolyte according to claim 10, wherein the protonic polar solvent is at least one selected from the group consisting of ethanol, isopropanol, n-butanol, acetic acid, and nitromethane. The method of claim 1, wherein the second organic solvent is 60 to 99 wt% based on the total weight of the second suspension. The method for producing a solid electrolyte according to claim 1, wherein the mixed agitation in step (b) is carried out at a revolution rate of 100 to 500 rpm at a rate of 50 to 90 degrees per minute for 10 to 14 hours. The method of claim 1, wherein the first suspension and the second suspension are mixed in a ratio of 30:70 to 70:30 based on the weight ratio. The method according to claim 1, wherein the vacuum drying of step (c) is performed at 100 to 250 degrees. The method according to claim 1,
(D) subjecting the compound prepared in step (c) to a heat treatment at 400 to 700 degrees Celsius;
Further comprising the steps of: A solid electrolyte produced by the manufacturing method according to claim 1. 18. The solid electrolyte according to claim 17, wherein the solid electrolyte has an ion conductivity of 1 * 10 ^-5 to 5 * 10 ^-3 S / cm at 25 degrees. A pre-solid battery comprising the solid electrolyte according to claim 17.

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