KR20190051519A - Solid electrolyte material, methods for manufacturing the same, and all solid state battery including the same - Google Patents

Abstract

The present invention relates to a solid electrolyte material, which has excellent safety, and secures sufficient ion conductivity, and to a manufacturing method thereof, and an all-solid-state battery including the same. The solid electrolyte material of the present invention comprises a sulfide-based compound represented by chemical formula 1, Na_aSn_bSb_cS_d, and having 1.0 x 10^-4 S/cm or more of the ion conductivity at the temperature of 30°C.

Description

TECHNICAL FIELD [0001] The present invention relates to a solid electrolyte material, a method for producing the solid electrolyte material, and a whole solid battery including the solid electrolyte material.

The present invention relates to a solid electrolyte material having good ion conductivity and excellent economy, a method for producing the solid electrolyte material, and an all solid battery including the same.

The secondary battery has mainly been applied to a small-sized field such as a mobile device or a notebook computer. However, recently, the research direction has been expanded to middle and large-sized fields such as an energy storage system (ESS) and an electric vehicle .

In the case of such a large-sized secondary battery, unlike a small-sized battery, operating environment (for example, temperature, shock) is not only severe but also requires more batteries. There is a need.

However, most of the currently commercialized secondary batteries use an organic liquid electrolyte in which a metal salt is dissolved in a flammable organic solvent, which poses a potential risk of leakage, ignition, explosion, and the like.

Accordingly, the use of a solid electrolyte in place of the organic liquid electrolyte has attracted attention as an alternative to overcome the safety problem.

Specifically, a battery using a solid electrolyte, that is, a whole solid battery, can be classified into a thin film type and a thick film type. Among these, a thick-film type all-solid-state cell is a so-called composite-type all-solid-state cell, and in the currently commercialized secondary battery, the organic liquid electrolyte is simply replaced with a solid electrolyte.

On the other hand, most of the currently commercialized secondary batteries use lithium as a solid electrolyte material, but the distribution range of lithium is limited not only in the world but also in the reserves, which are disadvantageous in terms of price and continuous supply of materials.

Accordingly, there is a movement to utilize sodium, which is widely distributed on the earth, as a solid electrolyte material.

However, when sodium is used as a solid electrolyte material, ion conductivity lower than lithium is a problem.

In order to solve the above-mentioned problems, the present invention aims to provide a sulfide-based solid electrolyte material, a method for producing the sulfide-based solid electrolyte material, and a whole solid battery including the sulfide-based solid electrolyte material.

In one embodiment of the present invention, there is provided a solid electrolyte material comprising a sulfide-based compound. Specifically, the sulfide compound is represented by the following formula (1).

???????? Na _a Sn _b Sb _c S _d

In the formula 1, 0 < a? 6, 0 < b? 6, 0 < c?

More specifically, the sulfide compound may be represented by the following formula (2).

???????? Na _4-x Sn _1-x Sb _x S ₄ ?????

In Formula 2, 0 < x < 1.

10^-5 S/cm 이상, 바람직하게는 1.0

10^-4 S/cm 이상, 더 바람직하게는 2.0

10^-4 S/cm 이상인 것일 수 있다.The sulfide compound preferably has an ionic conductivity of 1.0

10 ^-5 S / cm or more, preferably 1.0

10 ^-4 S / cm or more, more preferably 2.0

10 ^-4 S / cm or more.

The sulfide compound may be amorphous, crystalline, or a mixture thereof.

In another embodiment of the present invention, there is provided a process for producing a sulfide-based compound represented by the general formula (1) or (2), which comprises heat-treating a mixture of a sodium raw material, an antimony raw material, a tin raw material, , And a method for producing a sulfide-based solid electrolyte material.

In another embodiment of the present invention, cathode; And a solid electrolyte, wherein the solid electrolyte material comprising the sulfide-based compound represented by the general formula (1) or (2) is used as the solid electrolyte, or the solid electrolyte material comprising the sulfide-based compound represented by the general formula Is applied to the positive electrode and / or the negative electrode.

According to one embodiment of the present invention, it is possible to provide a sulfide-based solid electrolyte material which has a superior safety to an organic liquid electrolyte, secures sufficient ion conductivity, is stably dissolved in a solvent, and has excellent storage stability.

According to another embodiment of the present invention, there is provided a method of manufacturing a sulfide-based solid electrolyte material having excellent properties by a simple method according to a solid-phase method.

In addition, according to another embodiment of the present invention, by including the sulfide-based solid electrolyte material, it is possible to provide a pre-solid battery in which battery performance is stably exhibited while safety is secured as compared with a battery using the organic liquid electrolyte .

Fig. 1 shows the results of X-ray diffraction analysis of each solid electrolyte material according to Example 1 and Comparative Example 1 of the present invention.
Figs. 2A to 2C are graphs showing the relationship between Na &lt; _{3 &} gt _{; 75} Sn _{0 . 75} Sb _{0 . As a} result of the crystal structure analysis of ₂₅ S _4, the crystal structure analysis result of Na ₄ SnS _{4 and} the crystal structure analysis result of Na ₃ SbS ₄ are shown, respectively.
Fig. 3 shows the ionic conductivities of the respective solid electrolyte materials according to Examples 1 to 3 and Comparative Example 1 of the present invention.
4 is a schematic view of a cell for measurement of ion conductivity of a solid electrolyte material according to Evaluation Example 3 of the present invention.
5 shows changes in ionic conductivity of the solid electrolyte material according to Evaluation Example 4 of the present invention before and after air storage.
6 schematically shows a structure of a pre-solid battery according to Evaluation Example 5 of the present invention.
Fig. 7 shows a charge / discharge capacity profile according to a driving voltage of an all solid-state cell according to Evaluation Example 5 of the present invention.
8 shows the number of cycles according to the charging capacity of the all-solid-state cell according to the evaluation example 5 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

Sulfide-based solid electrolyte material

10^-5 S/cm 이상, 바람직하게는 1.0

10^-4 S/cm 이상, 더 바람직하게는 2.0

10^-4 S/cm 이상인 것일 수 있다.In one embodiment of the present invention, there is provided a solid electrolyte material comprising a sulfide-based compound. Specifically, the sulfide compound is represented by the following formula (1) and has an ionic conductivity of 1.0

10 ^-5 S / cm or more, preferably 1.0

10 ^-4 S / cm or more, more preferably 2.0

10 ^-4 S / cm or more.

???????? Na _a Sn _b Sb _c S _d

In the formula 1, 0 < a? 6, 0 < b? 6, 0 < c?

In the above formula (1), 0 <a <6, 0 <b <6, 0 <c <4.5, and 0 <d <5 are preferable.

More specifically, the sulfide compound may be represented by the following formula (2).

???????? Na _4-x Sn _1-x Sb _x S ₄ ?????

In Formula 2, 0 < x < 1.

In the above formula (2), 0 < x < 0.5 is more preferable, and 0.02 x 0.33 is more preferable.

In the above formula (1) or (2), the composition ratio of each element can be controlled by adjusting the compounding amount of the raw material when the compound is prepared.

The sulfide-based compound may be amorphous, crystalline, or a mixture thereof. Preferably, the sulfide-based solid electrolyte material of the present invention has a tetragonal crystal structure.

The sulfide compound may have a peak in the range of 2 to 17 in the range of 17 to 19 °, in the range of 21 to 23 °, and in the range of 36 to 38 ° in the X-ray diffraction analysis (XRD analysis) .

Process for producing sulfide-based solid electrolyte material

In another embodiment of the present invention, there is provided a process for producing a sulfide-based solid electrolyte material.

The sulfide-based solid electrolyte material of the present invention is preferably produced by the solid phase method. The solid phase method is a method of synthesizing a compound by mixing raw materials and heating at a predetermined temperature.

Specifically, the sulfide-based solid electrolyte material of the present invention is obtained by compounding the respective raw materials so as to satisfy the stoichiometric molar ratio of the above formula (1) or (2) and then subjecting the sulfide- And the like.

The heat treatment may be performed in a temperature range of more than 350 DEG C to 800 DEG C or less. When the heat treatment conditions by the solid phase method are below 350 ° C, the ionic conductivity of the synthesized material is low, which is not suitable as a solid electrolyte. On the other hand, when the heat treatment conditions by the solid phase method are controlled to be from 350 DEG C to 800 DEG C, a material exhibiting an appropriate ion conductivity can be synthesized.

As raw materials for preparing the compounds of the above formula (1) or (2), sodium raw material, antimony raw material, tin raw material and sulfur raw material can be used. The sodium raw material, the antimony raw material, the tin raw material and the sulfur raw material may be Na ₂ S, SnS ₂ , Sb ₂ S _{3 ,} and S, respectively _, and these raw materials may be all commercially available have.

Based powder of the solid electrolyte material, which comprises the step of heat-treating the mixture of the sodium raw material, the antimony raw material, the tin raw material, and the sulfur raw material, and then the material powder can be treated with an appropriate solvent. The solvent is not particularly limited as long as it is usually used in the production process of a battery such as water and an organic solvent.

The solid electrolyte material powder of the present invention dissolved in a solvent may be used after removing the solvent and recrystallizing it. The sulfide-based solid electrolyte material of the present invention can exhibit sufficient ion conductivity even after solution treatment and / or recrystallization.

All solid-state cells

In another embodiment of the present invention, cathode; And a solid electrolyte, wherein the sulfide-based solid electrolyte material is used as the solid electrolyte, or the sulfide-based solid electrolyte material is applied to the anode and / or the cathode .

By applying the above-described solid electrolyte material, the battery of the present invention can stably exhibit battery performance while securing the safety of the battery using the organic liquid electrolyte.

The components of the battery other than the above-described solid electrolyte material can be generally used those known in the art.

For example, the pre-solid battery of the present invention comprises a cathode active material layer containing a cathode active material;

A negative electrode active material layer containing a negative electrode active material; An electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer; A positive electrode current collector for collecting the positive electrode active material layer; An anode current collector for collecting the anode active material layer; And a battery case for housing these members. In the present invention, the above-described sulfide-based solid electrolyte material may be contained in at least one of the positive active material layer, the negative active material layer, and the electrolyte layer.

The electrolyte layer of the present invention is a layer formed between the positive electrode active material layer and the negative electrode active material layer. The electrolyte layer is not particularly limited as long as it is a layer capable of conducting ions, but it is preferably a solid electrolyte layer composed of a solid electrolyte material. This is because a battery having high safety can be obtained as compared with a battery using an electrolytic solution. In the present invention, the solid electrolyte layer preferably contains the above-described sulfide-based solid electrolyte material, and the ratio of the sulfide-based solid electrolyte material contained in the solid electrolyte layer may be within a range of 10% by volume to 100% by volume , And 50 vol.% To 100 vol.%. In the present invention, since the solid electrolyte layer contains the sulfide-based solid electrolyte material at a high ratio, a high output battery can be obtained. The thickness of the solid electrolyte layer may be within a range of 0.1 mu m to 1000 mu m, preferably within a range of 0.1 mu m to 300 mu m. As a method for forming the solid electrolyte layer, for example, a method of compression-molding a solid electrolyte material and the like can be given.

The cathode active material layer of the present invention is a layer containing at least a cathode active material and may contain at least one of a solid electrolyte material, a conductive fire and a binder if necessary. Particularly, in the present invention, it is preferable that the positive electrode active material layer contains the above-described sulfide-based solid electrolyte material, and the ratio of the sulfide-based solid electrolyte material contained in the positive electrode active material layer varies depending on the kind of battery, To 80% by volume, preferably within a range of 1% by volume to 60% by volume, particularly preferably within a range of 10% by volume to 50% by volume. The thickness of the positive electrode active material layer is preferably in the range of 0.1 mu m to 1000 mu m.

Examples of the positive electrode active material used in the battery include LiCoO ₂ , LiMnO ₂ , Li ₂ NiMn ₃ O ₈ , LiVO ₂ , LiCrO ₂ , LiFePO ₄ , LiCoPO ₄ , LiNiO ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , and the like.

The cathode active material layer of the present invention may also contain a conductive fire. The conductivity of the positive electrode active material layer can be improved by the addition of the conductive fire. Examples of the conductive fire include acetylene black, ketjen black, carbon fiber, and the like. The positive electrode active material layer of the present invention may contain a binder. Examples of the binder include fluorine-containing binder such as polytetrafluoroethylene (PTFE).

The negative electrode active material layer of the present invention is a layer containing at least the negative electrode active material and may contain at least one of a solid electrolyte material, a conductive fire and a binder if necessary. Particularly, in the present invention, it is preferable that the anode active material layer contains the above-described sulfide-based solid electrolyte material, and the ratio of the sulfide-based solid electrolyte material contained in the anode active material layer varies depending on the type of battery, To 80% by volume, preferably within a range of 1% by volume to 60% by volume, particularly preferably within a range of 10% by volume to 50% by volume. The thickness of the negative electrode active material layer is preferably in the range of 0.1 占 퐉 to 1000 占 퐉, for example.

Examples of the negative electrode active material include a metal active material and a carbon active material. Examples of the metal active material include In, Al, Si and Sn. Examples of the carbon active material include mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, soft carbon, and the like. The kinds of the conductive fire and the binder used for the negative electrode active material layer are the same as those for the positive electrode active material layer described above.

The battery of the present invention may have a positive electrode collector for collecting the positive electrode active material layer and a negative electrode collector for collecting the negative electrode active material layer having at least the above-described electrolyte layer, positive electrode active material layer and negative electrode active material layer.

As the material of the positive electrode current collector, for example, SUS, aluminum, nickel, iron, titanium, carbon and the like are exemplified, and SUS is preferable. On the other hand, examples of the material of the negative electrode current collector include SUS, copper, nickel and carbon, and SUS is preferable. The thickness and shape of the positive electrode current collector and the negative electrode current collector can be appropriately selected depending on the use of the battery and the like.

A battery case of a general battery can be used for the battery case used in the present invention. Examples of the battery case include a battery case made of SUS.

The battery of the present invention is preferably a secondary battery, and examples of the battery shape of the present invention include a coin type, a laminate type, a cylindrical type and a prism type.

Further, the method for manufacturing a battery of the present invention is not particularly limited, and a method similar to a general battery manufacturing method may be used. For example, when the battery of the present invention is a pre-solid battery, as one example of its manufacturing method, a material constituting the positive electrode active material layer, a material constituting the solid electrolyte layer and a material constituting the negative electrode active material layer are sequentially pressed, And a manufacturing method including the step of housing the battery case inside the casing and caulking the battery case.

Hereinafter, preferred embodiments of the present invention, comparative examples thereof, and evaluation examples thereof will be described. However, the following examples are only a preferred embodiment of the present invention, and the present invention is not limited to the following examples.

Example 1

_{Na 4 - x Sn 1 - x} Sb x S 4 x is 0.01, 0.02, 0.05, 0.15, 0.20, 0.25, 0.30, 0.40, 0.45, Na 2 S so as to satisfy 0.50, respectively (Sigma Aldrich Co.) according to, Sb ₂ S ₃ (manufactured by Sigma Aldrich, 99.5%), SnS ₂ (manufactured by Kojundo Chemical Laboratory, 99.9%) and S (manufactured by Alfa Aesar, 99.5%) were uniformly mixed and then heat treated at 450 ° C. for 12 hours in a vacuum state , Na _{4 - x} Sn _{1 - x} Sb _x S ₄ powder (x is 0.01, 0.02, 0.05, 0.15, 0.20, 0.25, 0.30, 0.40, 0.45, 0.50). The composition of Na _{4 - x} Sn _{1 - x} Sb _x S ₄ was measured by ICPOES using 720-ES (Varian Corp.).

Example 2

Na _{3 . 75} Sn _{0 . 75} Sb _{0 . 25} S ₄ stoichiometric to Na ₂ S (Sigma Aldrich Ltd.) so as to satisfy a molar ratio of, Sb ₂ S ₃ (Sigma Aldrich manufacture, 99.5%), SnS ₂ (Kojundo Chemical Laboratory Manufacture, 99.9%) and S (manufactured Alfa Aesar , 99.5%) were uniformly mixed and then heat-treated at 550 캜 for 12 hours under vacuum to obtain Na _3.75 Sn _0.75 Sb _0.25 S ₄ powder.

Example  3

Na ₂ S (manufactured by Sigma Aldrich), Sb ₂ S ₃ (manufactured by Sigma Aldrich, 99.5%) so that x satisfies 0.15, 0.20, 0.25, 0.30 and 0.35 in Na _{4 - x} Sn _{1 - x} Sb _x S ₄ , , SnS ₂ (manufactured by Kojundo Chemical Laboratory, 99.9%) and S (manufactured by Alfa Aesar, 99.5%) were uniformly mixed and then heat-treated at 450 ° C. for 12 hours in a vacuum state to obtain Na _{4 - x} Sn _{1 - x} Sb _x S ₄ powder (x = 0.15, 0.20, 0.25, 0.30, 0.35), respectively.

Each of the obtained solid electrolyte materials was dissolved in deionized water under dry Ar. The obtained solid electrolyte material was completely dissolved in deionized water without generating harmful H ₂ S gas.

Then, by drying the soluble material in a vacuum at room temperature to evaporate water and recrystallized each solid electrolyte material, to heat treatment at 450 ℃ in vacuo _{Na 4 - x Sn 1 -x Sb} x S 4 powder (x 0.15, 0.20, 0.25, 0.30, 0.35), respectively.

Comparative Example 1

Na ₂ S (manufactured by Sigma Aldrich) and SnS ₂ (manufactured by Sigma Aldrich) were mixed so as to satisfy the stoichiometric molar ratio of Na ₄ SnS ₄ (Manufactured by Kojundo Chemical Laboratory, 99.9%) were uniformly mixed and then heat-treated at 450 캜 for 12 hours under vacuum to obtain Na ₄ SnS ₄ powder.

Evaluation Example 1: Structure confirmation by XRD

The solid electrolyte materials each having x of 0.01, 0.02, 0.05, 0.15, 0.25, 0.30, 0.40 and 0.50 in Na _{4 - x} Sn _{1 - x} Sb _x S ₄ obtained in Example 1 and the solid electrolytes obtained in Comparative Example 1 The material was subjected to X-ray diffraction analysis (XRD analysis).

X-ray diffraction analysis was carried out at room temperature using a Bragg-Brentano X-ray diffractometer (manufactured by PANalytical Empyrean) and data were acquired with a 0.0130 ° stride in an angle range of 10 ° ≤ 2θ ≤ 150 °. The results of the X-ray diffraction analysis are shown in Fig.

In Fig. 1, x = 0 corresponds to Comparative Example 1, and in other cases corresponds to the solid electrolyte material of Example 1.

As a reference example, the results of XRD in the known known tetragonal structure of Na ₃ SbS ₄ (when x is 1 in Na _{4 - x} Sn _{1 - x} Sb _x S ₄ ) are also shown. By comparing the XRD pattern of Na ₃ SbS ₄ (x = 1) of Reference Example and Na ₄ SnS ₄ (x = 0) of Comparative Example 1 with the XRD pattern of the solid electrolyte material obtained in Example 1, .

According to FIG. 1, the solid electrolyte material of Reference Example 1 or Comparative Example 1 exhibits a peak only at a position similar to that of Na ₃ SbS ₄ or Na ₄ SnS ₄ known in the art, whereas the solid electrolyte material of Reference Example 1 Peaks are observed at unreported locations. Specifically, it can be seen that XRD peaks appear at high intensity in the range of 2? In the range of 17 to 19, in the range of 36 to 38, and in the range of 21 to 23, respectively.

As a result, it can be seen that the solid electrolyte material of Example 1 has a new crystal structure different from the solid electrolyte materials of Reference Example 1 and Comparative Example 1.

Further, it can be confirmed that the new crystal structure is obtained in a high yield in the range of 0.02? X? 0.03. It can be seen that when x = 0.4 or x = 0.5, which is a higher x value, a considerable amount of Na ₃ SbS ₄ is formed in the second phase.

Evaluation Example 2: Analysis of crystal structure

Example x obtained in the first 0.25 a solid electrolyte material for the _{(Na 3. 75 Sn 0.} 75 Sb 0. 25 S 4), powders profile analysis program (powder profile refinement program) GSAS and a single crystal structure analysis program (single crystal structure refinement program) CRYSTALS was used to determine the theoretical structure (Ab-initio structure).

Na _{3 . 75} Sn _{0 . 75} Sb _{0 .} The analysis result of the crystal structure of the solid electrolyte material of ₂₅ S ₄ is shown in FIG. As a reference example, the analysis results of Na ₄ SnS ₄ and Na ₃ SbS ₄ are shown in FIG. 2B and FIG. 2C.

Referring to Figure 2a, Na _{3. 75} Sn _{0 . 75} Sb _{0 .} The solid electrolyte material of ₂₅ S ₄ showed a tetragonal crystal structure. When compared to Fig. 2b and Fig. 2c, Na ₄ SnS ₄ or Na ₃ SbS ₄ as compared to having the one type of SnS ₄ tetrahedra or SbS _4, Na _{3. 75} Sn _{0 . 75} Sb _{0 . 25} S ₄ showed crystallographic and distinctive site morphology. Namely, the sites of only Sn and Sb-rich (Sb / Sn mixed) sites were shown. The SnS ₄ tetrahedron and the Sb rich (Sb / Sn mixed) tetrahedron were arranged such that the SnS ₄ tetrahedron forms a pseudo cubic lattice, and the center of the sub-cell is filled with the Sb rich tetrahedron. However, only about half of the center is filled with Sb-rich tetrahedra, and the other half is empty.

As a result of the above crystal structure analysis, it can be seen that the solid electrolyte material of Na _{4 - x} Sn _{1 - x} Sb _x S ₄ has a new crystal structure different from that of the conventional materials.

Evaluation Example 3: Evaluation of ionic conductivity and activation energy

For each of the solid electrolyte materials obtained in Example 1, x being 0.02, 0.05, 0.15, 0.20, 0.25, 0.40, 0.45 and 0.50, the solid electrolyte material obtained in Example 2 and the solid electrolyte material obtained in Comparative Example 1, Conductivity and activation energy were measured and the results are shown in FIG. 3 and Table 1.

The ion conductivity of each of the solid electrolyte materials obtained in Example 3 was 0.15, 0.20, 0.25, 0.30, and 0.35, and the results are shown in FIG.

The ionic conductivity was measured by electrochemical impedance spectroscopy after each solid electrolyte material was cold-pressed at 370 MPa into pellets (diameter: 6 mm). FIG. 4 is a schematic view of a cell for measuring ionic conductivity.

10^-4 S/cm의 이온 전도도를 나타냈다. 0.40=x≤0.50에서는 최대치보다 약간 이온 전도도가 감소 경향을 나타냈다.According to FIG. 3 and Table 1, Comparative Example 1 had no ionic conductivity, whereas Example 1 exhibited a high ionic conductivity. In the solid electrolyte material having x of 0.4, the maximum value was 3.2

Ion conductivity of 10 ^-4 S / cm was shown. At 0.40 = x &lt; = 0. 50, the ionic conductivity tended to be slightly lower than the maximum.

10^-4 S/cm로, 더욱 높은 이온 전도도를 나타냈다.The solid electrolyte material of Example 2 synthesized by heat treatment at 550 占 폚 was 5.0

10 ^-4 S / cm, indicating a higher ionic conductivity.

3, the solution-treated and recrystallized solid electrolyte material of Example 3 exhibited a slight decrease in ion conductivity as compared with the solid electrolyte material of Example 1. However, even after solution treatment and recrystallization, Conductivity was shown, and x exhibited the maximum ionic conductivity at 0.25.

From the above results, it can be confirmed that the solid electrolyte material of Na _4-x Sn _{1 -x} Sb _x S _{4 having} a new structure generated by the antimony substitution has high ion conductivity. In addition, the solid electrolyte material of Na _{4 - x} Sn _{1 - x} Sb _x S ₄ has excellent solubility in water and shows high ionic conductivity even after recrystallization after solution treatment, which is also excellent in solution processability .

The synthesis temperature ( ^o C) x
(Na _4-x Sn _1-x Sb _x S ₄ ) Ion conductivity
(30 ^o Cs / cm) Activation energy
(eV) Comparative Example 1 450 0 - - Example 1 450 0.02

10^-5 6.0

10 ^-5 0.33 Example 1 450 0.05 1.8

10 ^-4 0.32 Example 1 450 0.15 2.2

10 ^-4 0.35 Example 1 450 0.20 2.2

10 ^-4 0.37 Example 1 450 0.25 2.4

10 ^-4 0.39 Example 1 450 0.40 3.2

10 ^-4 0.39 Example 1 450 0.45 2.6

10 ^-4 0.38 Example 1 450 0.50 2.2

10 ^-4 0.37 Example 2 550 0.25 5.0

10 ^-4 0.35

Evaluation Example 4: Evaluation of stability

Example 1 0.25 x obtained in a solid electrolyte material _{(Na 3. 75 Sn 0.} 75 Sb 0. 25 S 4) 24 hours under the 200mg, dry air (a mixture of 21/79 by volume of O ₂ and N ₂₎ After exposure, the ion conductivity according to the temperature was measured in the same manner as in Evaluation Example 2. The results are shown in Fig.

According to Fig. 5, it can be seen that the solid electrolyte material of Example 1 has a very small change in ionic conductivity before and after air storage.

From the above results, it can be confirmed that the solid electrolyte material of Na _{4 - x} Sn _{1 - x} Sb _x S ₄ maintains high ion conductivity in a stable state in air.

Evaluation Example 5: Performance evaluation of all solid batteries

Using the solid electrolyte material of Example 1, a pre-solid battery having the structure shown in Fig. 6 was produced.

Specifically, the pre-solid battery shown in Fig. 6 has a structure in which an electrode layer, a solid electrolyte layer, and a Na-Sn based alloy layer are sequentially stacked. Here, the solid electrolyte of Example 1 was applied to the solid electrolyte layer and the electrode layer.

More specifically, in a cylindrical mold of f 13 mm, Na ₃ Sn alloy 50 mg, Example x 1 0.25 a solid electrolyte material _{(Na 3. 75 Sn 0.} 75 Sb 0. 25 S 4) 150 mg, And 10 mg of the electrode material were laminated in this order, and then a pressure of 370 MPa was applied to form a pellet.

The electrode materials include, x obtained in Example 1 was used as a 0.25 a mixture of a solid electrolyte material _{(Na 3. 75 Sn 0.} 75 Sb 0. 25 S 4) and TiS ₂ (active material). The mixture was hand-mixed so that the weight ratio of solid electrolyte: active material was 50:50.

For a battery of applying the mixture, from 1.0 to 2.5 V driving voltage (vs. Na / Na ⁺⁾ at 30 ℃, it was evaluated by applying a constant current of 50 to 500 μA / cm ^2.

FIG. 7 shows a charge / discharge capacity profile at a driving voltage of 1.0 to 2.5 V when a constant current of 100, 150, 350, and 500 μA / cm ² is applied, respectively. For each constant current, the profile according to the number of cycles is also shown.

Referring to Figure 7, Na _{3. 75} Sn _{0 . 75} Sb _{0 .} It can be seen that all solid-state cells using ₂₅ S ₄ exhibit a high reversible capacity. Also, the high reversible capacity was maintained even when the number of charge / discharge cycles increased.

8 shows the number of cycles according to the charging capacity when a constant current of 50, 100, 150, 250, 350, and 500 μA / cm ² is applied.

Referring to Figure 8, Na _{3. 75} Sn _{0 . 75} Sb _{0 .} It can be seen that all solid-state cells using ₂₅ S ₄ maintain the charge capacity even when the number of charge-discharge cycles is increased.

From the above results, it can be confirmed that the solid electrolyte material of Na _{4 - x} Sn _{1 - x} Sb _x S ₄ has excellent charge / discharge performance and exhibits excellent performance as a material of all solid batteries.

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 present invention as defined by the following claims. As will be understood by those skilled in the art. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (11)

Represented by the following general formula (1) and having an ionic conductivity of 1.0

^10-4, including S / cm or more sulfide-based compound,
Sulfide based solid electrolyte materials.
???????? Na _a Sn _b Sb _c S _d
(Wherein 0 < a < = 6, 0 < b < = 6, 0 &
The method according to claim 1,
Wherein the sulfide compound is represented by the following formula (2)
Sulfide based solid electrolyte materials.
???????? Na _{4 - x} Sn _{1 - x} Sb _x S ₄ ?????
(In the formula 2, 0 < x < 1)
3. The method of claim 2,
Wherein 0 < x < 0.5 in Formula 2,
Sulfide based solid electrolyte materials.
3. The method according to claim 1 or 2,
Wherein the sulfide-based compound is crystalline.
Sulfide based solid electrolyte materials.
3. The method according to claim 1 or 2,
Wherein the sulfide-based compound exhibits an XRD peak at 2? In the range of 17 to 19 °, in the range of 21 to 23 °, and in the range of 36 to 38 °,
Sulfide based solid electrolyte materials.
3. The method according to claim 1 or 2,
Wherein the crystal structure of the sulfide-based compound is tetragonal.
Sulfide based solid electrolyte materials.
Mixing a sodium raw material, an antimony raw material, a tin raw material, and a sulfur raw material; Heat treating the resulting mixture; And a step of obtaining a sulfide-based compound represented by the following formula (1) or (2)
A method for producing a sulfide-based solid electrolyte material.
???????? Na _a Sn _b Sb _c S _d
(0 <a? 6, 0 <b? 6, 0 <c? 6, and <0d?
???????? Na _{4 - x} Sn _{1 - x} Sb _x S ₄ ?????
(In the formula 2, 0 < x < 1)
8. The method of claim 7,
Wherein the step of heat-treating the mixture of the sodium raw material, the antimony raw material, the tin raw material, and the sulfur raw material is performed in a temperature range of from 350 ° C to 800 ° C.
A method for producing a sulfide-based solid electrolyte material.
8. The method of claim 7,
Wherein the sodium raw material, the antimony raw material, the tin raw material, and the sulfur raw material are Na ₂ S, SnS ₂ , Sb ₂ S _{3 ,} and S,
A method for producing a sulfide-based solid electrolyte material.
8. The method of claim 7,
Dissolving the obtained sulfide compound represented by the above formula (1) or (2) in a solvent; And evaporating the solvent from the solution and recrystallizing the sulfide-based compound.
A method for producing a sulfide-based solid electrolyte material.
anode;
cathode; And
Comprising a solid electrolyte,
The solid electrolyte material according to any one of claims 1 to 3, which is contained in at least one of the solid electrolyte, the positive electrode and the negative electrode.
All solid state batteries.

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