JP2012009255A - Sulfide based solid electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sulfide based solid electrolyte battery in which generation of hydrogen sulfide can be minimized.SOLUTION: In the solid electrolyte battery comprising a positive electrode, a negative electrode, and a sulfide based solid electrolyte layer interposed between the positive electrode and the negative electrode, outer periphery of the sulfide based solid electrolyte layer is coated, at least partially, with a water repellent coat containing a water repellent. When the sulfide based solid electrolyte layer touches moisture and deliquesces, the deliquesced sulfide based solid electrolyte can be brought to the surface of the water repellent coat on the side opposite from the sulfide based solid electrolyte layer.

Description

  The present invention relates to a sulfide-based solid electrolyte battery that can suppress generation of hydrogen sulfide.

  In recent years, with the rapid spread of information-related equipment such as personal computers, video cameras, and mobile phones, and communication equipment, development of batteries that are used as power sources has been regarded as important. Also in the automobile industry, development of high-power and high-capacity batteries for electric vehicles and hybrid vehicles is in progress. Among various secondary batteries, lithium ion batteries are attracting attention because of their high energy density and output.

Among lithium-ion batteries, lithium-ion batteries that use a solid electrolyte as the electrolyte and are fully solidified do not use a flammable organic solvent in the battery. It is considered excellent. A sulfide-based solid electrolyte is known as a solid electrolyte material used for such a solid electrolyte.
However, since sulfide-based solid electrolyte materials easily react with moisture, batteries using sulfide-based solid electrolyte materials are prone to deterioration due to generation of hydrogen sulfide, and there is a problem that the battery life is short. It was.

Patent Document 1 discloses a solid battery in which a power generation element is coated with a protective film having a thermal conductivity of 10 Wm ⁻¹ K ⁻¹ or more and containing a filler having water repellency, It is described that when the filler has water repellency, the moisture permeability of the protective film is improved.

JP 2006-351326 A

However, although the protective film described in Patent Document 1 has an effect of preventing passage of moisture, when the power generation element includes a sulfide-based solid electrolyte having deliquescence, moisture has penetrated into the power generation element. At the time, the electrolyte reacts with moisture that has penetrated to deliquesce, to generate hydrogen sulfide, and further, the electrolyte deliquess penetrates into the power generation element, and the reaction between the electrolyte and water proceeds continuously, Since hydrogen sulfide is generated, there is a problem that deterioration inside the power generation element proceeds.
The present invention has been accomplished in view of the above circumstances, and an object thereof is to provide a sulfide-based solid electrolyte battery capable of suppressing the generation of hydrogen sulfide.

  The sulfide-based solid electrolyte battery of the present invention is a solid electrolyte battery comprising at least a positive electrode, a negative electrode, and a sulfide-based solid electrolyte layer interposed between the positive electrode and the negative electrode. At least a part of the outer periphery of the solid electrolyte layer is covered with a water-repellent coat containing a water repellent, and when the sulfide-based solid electrolyte layer comes into contact with moisture and is liquefied, the liquefied sulfide-based solid electrolyte Is characterized in that it can be put out on the surface of the water-repellent coat opposite to the sulfide-based solid electrolyte layer.

  In the sulfide-based solid electrolyte battery of the present invention, the contact angle of water with respect to the water-repellent coat is preferably 70 ° or more.

  In the sulfide-based solid electrolyte battery of the present invention, the water repellent is a water repellent selected from the group consisting of a fluororesin-containing water repellent, a fluoroalkyl group-containing silane compound, and a dimethyl silicone-based water repellent. Is preferred.

In the sulfide-based solid electrolyte battery of the present invention, the sulfide-based solid electrolyte may be Li ₂ S—SiS ₂ , Li ₂ S—P ₂ S ₅ , Li ₂ S—GeS ₂ , and Li ₂ S—. A sulfide-based solid electrolyte selected from the group consisting of B ₂ S ₃ systems is preferred.

According to the present invention, at least part of the outer periphery of the sulfide-based solid electrolyte layer is covered with a water-repellent coat containing a water-repellent agent, thereby allowing moisture to pass from the external environment to the sulfide-based solid electrolyte layer. In addition, when the sulfide-based solid electrolyte layer comes into contact with moisture and is liquefied, the liquefied sulfide-based solid electrolyte is expelled to the surface of the water-repellent coating opposite to the solid electrolyte layer, and the sulfide-based solid electrolyte layer Reaction between the solid electrolyte layer and moisture and generation of hydrogen sulfide due to the reaction can be suppressed.
Therefore, the sulfide-based solid electrolyte battery of the present invention suppresses the deliquescence of the sulfide-based solid electrolyte layer only on the surface, prevents the liquefied sulfide-based solid electrolyte from entering the sulfide-based solid electrolyte layer, Generation of hydrogen sulfide due to continuous reaction between the sulfide-based solid electrolyte layer and water due to the intrusion of the deliquesce product is stopped, and deterioration of the inside of the sulfide-based solid electrolyte layer is prevented from proceeding.

(A) It is a figure explaining notionally a mode when the sulfide solid electrolyte layer which is not coat | covered with the water repellent coat touches moisture, (b) The sulfide solid electrolyte layer coat | covered with the water repellent coat It is a figure which illustrates notionally a state when water touches moisture. (A) It is a figure which shows typically the structure which provides a water-repellent coat in the outer periphery of the sulfide type solid electrolyte layer which concerns on this invention, (b) The structure which provides a water-repellent coat in the outer periphery of the electric power generation element which concerns on this invention It is a figure shown typically. It is a figure which shows an example of the laminated structure which the sulfide type solid electrolyte battery which concerns on this invention has, Comprising: It is the figure which showed typically the cross section cut | disconnected in the lamination direction. 3 is a bar graph showing the amount of hydrogen sulfide generated in 300 seconds after exposure of the sulfide-based solid electrolyte layer obtained in Example 1, Comparative Example 1 and Comparative Example 2 to the atmosphere. 7 is a bar graph showing the amount of hydrogen sulfide generated in 300 seconds after exposure of the sulfide-based solid electrolyte layer obtained in Comparative Example 3 and Comparative Example 4 to the atmosphere.

  The sulfide-based solid electrolyte battery of the present invention is a solid electrolyte battery comprising at least a positive electrode, a negative electrode, and a sulfide-based solid electrolyte layer interposed between the positive electrode and the negative electrode. At least a part of the outer periphery of the solid electrolyte layer is covered with a water repellent coat containing a water repellent. As shown in FIG. 1 (a), a sulfide-based solid electrolyte layer not covered with a water-repellent coat (hereinafter sometimes simply referred to as “electrolyte layer”) reacts with moisture in the atmosphere to deliquesce. And hydrogen sulfide is generated. Furthermore, since the deliquescent electrolyte penetrates into the electrolyte layer and causes the reaction between the electrolyte layer and water to proceed continuously to generate hydrogen sulfide, in the electrolyte layer not covered with the water-repellent coat, Deterioration progresses to the inside. On the other hand, in the sulfide-based solid electrolyte battery according to the present invention, as shown in FIG. 1B, at least a part of the outer periphery of the sulfide-based solid electrolyte layer is covered with a water-repellent coat. Prevents the passage of moisture to the electrolyte layer. Furthermore, when the electrolyte layer comes into contact with moisture and is liquefied, the deliquescent electrolyte is expelled to the outside of the water-repellent coat while being localized on the surface of the electrolyte layer. . Therefore, when the outer periphery of the electrolyte layer is covered with a water-repellent coat, the electrolyte deliquescence is prevented from entering the inside of the electrolyte layer, and the continuous reaction between the electrolyte layer and water due to the intrusion of the deliquescence. Stops the generation of hydrogen sulfide due to, and prevents the deterioration inside the electrolyte layer from proceeding.

A typical example of the sulfide-based solid electrolyte battery according to the present invention has a configuration in which a water-repellent coat is directly provided on the outer peripheral surface of the sulfide solid-electrolyte layer (FIG. 2A). Further, as another typical example of the sulfide-based solid electrolyte battery according to the present invention, a configuration in which a water-repellent coating is provided on the outer peripheral surface of the power generation element including the sulfide solid-electrolyte layer and the electrodes can be taken (FIG. 2 ( b)).
Among these, from the viewpoint that the effect of the water repellent coat can be obtained more remarkably, it is preferable to take a configuration in which the water repellent coat is directly provided on the outer peripheral surface of the sulfide solid electrolyte layer as shown in FIG.
In the present invention, it is only necessary to cover at least a part of the outer periphery of the sulfide-based solid electrolyte layer with a water-repellent coat, but the effect of preventing the passage of moisture and the effect of expelling the deliquescent electrolyte are more excellent. As shown in FIG. 2 (a) and FIG. 2 (b), it is preferable to cover the entire outer periphery of the sulfide-based solid electrolyte layer with a water-repellent coat.

The sulfide-based solid electrolyte used in the present invention contains a sulfur component, has ionic conductivity, and dehydrates by reacting with moisture in the air to generate hydrogen sulfide. preferable.
Such sulfide-based solid electrolytes include a group consisting of Li ₂ S—SiS ₂ system, Li ₂ S—P ₂ S ₅ system, Li ₂ S—GeS ₂ system, and Li ₂ S—B ₂ S ₃ system. A sulfide-based solid electrolyte selected from can be used. _{Specifically, Li 2 S-P 2 S} 5, Li 2 S-P 2 S 3, Li 2 S-P 2 S 3 -P 2 S 5, Li 2 S-SiS 2, LiI-Li 2 S- _{P 2 S 5, LiI-Li} 2 S-SiS 2 -P 2 S 5, Li 2 S-SiS 2 -Li 4 SiO 4, Li 2 S-SiS 2 -Li 3 PO 4, Li 2 S-GeS 2, _{Li 3 PS 4 -Li 4 GeS 4} , LiGe 0.25 P 0.75 S 4, Li 2 S-B 2 S 3, Li 3.4 P 0.6 Si 0.4 S 4, Li 3.25 P Examples include _0.25 Ge _0.76 S ₄ , Li _4-x Ge _1-x P _x S ₄ , Li ₇ P ₃ S _{11, and the} like. Among these sulfide-based solid electrolytes, Li ₂ S—P ₂ S ₅ is preferable. This is because a solid electrolyte membrane having high ionic conductivity can be obtained.

Examples of the sulfide-based solid electrolyte include sulfur compounds such as diphosphorus pentasulfide (P ₂ S ₅ ), silicon sulfide (SiS ₂ ), germanium sulfide (GeS ₂ ), and boron sulfide (B ₂ S ₃ ), and sulfide. A glass raw material mixture obtained by mixing lithium (Li ₂ S) at a predetermined charging ratio is vitrified by performing a mechanical milling process or a melt quenching process to obtain a sulfide-based solid electrolyte powder. From the viewpoint of simplification of the manufacturing process, mechanical milling is preferred as the vitrification method. The melt quenching method is a general glass synthesis method, and can also be applied to a general method when employed as a synthesis method of sulfide-based solid electrolyte powder.

  The sulfide-based solid electrolyte may be contained not only in the sulfide-based solid electrolyte layer but also in the positive electrode and / or the negative electrode.

The water repellent used in the present invention is preferably a water repellent selected from the group consisting of a fluororesin-containing water repellent, a fluoroalkyl group-containing silane compound, and a dimethyl silicone-based water repellent.
Examples of the fluororesin-containing water repellent include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and the like.
Examples of the fluoroalkyl group-containing silane compound include (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, and the like.
Examples of the dimethyl silicone water repellent include dimethyl silicone oil.
Among these, a fluororesin-containing water repellent is preferable because of excellent water repellency and low reactivity.
In addition, as the water repellent, one of these can be used alone, or two or more different types can be mixed and used.

  The method for forming the water repellent coat is not particularly limited, but the solvent is prepared by dissolving the water repellent in a solvent and applying the solution to the outer periphery of the sulfide-based solid electrolyte layer to a uniform thickness using, for example, a spin coater. The method of drying is mentioned.

  The solvent for dissolving the water repellent is not particularly limited, but is preferably a solvent that exhibits good solubility in the water repellent and is volatile at room temperature, and examples thereof include a fluorine-based solvent. A fluorine-based solvent is also preferable as a solvent for dissolving the water repellent agent in view of low reactivity with the electrolyte.

  Moreover, EGC-1700, EGC-1720, etc. by Sumitomo 3M Co., Ltd. previously dissolved in a solvent can be used as the water repellent.

  The thickness of the water repellent coat is not particularly limited, but is preferably 0.1 nm to 10 μm, and particularly preferably 1 nm to 1 μm. When the thickness is within the above range, the water repellency is excellent and the deliquescent electrolyte can be removed.

The contact angle of water with respect to the water repellent coat containing a water repellent is preferably 70 ° or more. When the contact angle of water with respect to the water repellent coat is less than 70 ° C., the water repellency of the water repellent coat surface is insufficient, and the deliquescent electrolyte cannot be sufficiently ejected to the outside of the water repellent coat.
In addition, the contact angle of water with respect to the water-repellent coat can be measured based on, for example, JIS R 3257 (1999).

FIG. 3 is a view showing an example of a laminated structure of a sulfide-based solid electrolyte battery according to the present invention, and is a view schematically showing a cross section cut in the lamination direction. The sulfide-based solid electrolyte battery according to the present invention is not necessarily limited to this example.
A sulfide-based solid electrolyte battery 10 shown in FIG. 3 includes a positive electrode 6 including a positive electrode active material layer 2 and a positive electrode current collector 4, a negative electrode 7 including a negative electrode active material layer 3 and a negative electrode current collector 5, and the positive electrode 6. And an electrolyte layer 1 sandwiched between the negative electrodes 7 and a water-repellent coat 8 that covers the outer periphery of the electrolyte layer 1.
Hereinafter, the positive electrode and the negative electrode, the electrolyte layer, and other components (separator and the like), which are components of the sulfide-based solid electrolyte battery according to the present invention, will be described separately.

(Positive electrode)
The positive electrode used in the present invention includes a positive electrode active material layer containing a positive electrode active material, and preferably includes a positive electrode current collector and a positive electrode lead directly connected to the positive electrode current collector.
In addition to the positive electrode active material, the positive electrode active material layer may contain at least one of an electrolyte, a conductive material, and a binder as necessary. In particular, in the present invention, the electrolyte is preferably the sulfide solid electrolyte described above. This is because a solid electrolyte battery with an extremely small amount of hydrogen sulfide generation can be obtained.

Specific examples of the positive electrode active material used in the present invention include LiCoO ₂ , LiCoPO ₄ , LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , LiNiPO ₄ , LiMnPO ₄ , LiNiO ₂ , LiMn ₂ O _4. , LiMnO ₂ , LiCoMnO ₄ , Li ₂ NiMn ₃ O ₈ , Li ₃ Fe ₂ (PO ₄ ) ₃ LiFePO ₄ , LiVO ₂ , Li ₃ V ₂ (PO ₄ ) ₃ , LiCrO _{2 and the} like.

  The positive electrode active material is not particularly limited, but is preferably in the form of powder, and the average particle size is preferably in the range of 1 μm to 50 μm, for example. If the average particle size of the positive electrode active material is too small, the handleability may be deteriorated. If the average particle size of the positive electrode active material is too large, it may be difficult to obtain a flat positive electrode active material layer. Because. The average particle diameter of the positive electrode active material can be determined by measuring and averaging the particle diameter of the active material carrier observed with, for example, a scanning electron microscope (SEM).

The positive electrode active material layer may further contain an electrolyte. As the electrolyte, it is preferable to use the above-described sulfide-based solid electrolyte. In addition, an oxide-based solid electrolyte or the like can also be used.
Specifically, as the oxide-based solid electrolyte, LiPON (lithium phosphate oxynitride), Li _1.3 Al _0.3 Ti _0.7 (PO ₄ ) ₃ , La _0.51 Li _0.34 TiO _Examples include _0.74 , Li ₃ PO ₄ , Li ₂ SiO ₂ , Li ₂ SiO ₄ , Li _0.5 La _0.5 TiO ₃ , Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) _{3 and the} like. can do.
In addition, after the positive electrode active material layer is formed, the positive electrode active material layer may be pressed in order to improve the electrode density.
The content of the electrolyte in the positive electrode active material layer is usually in the range of 10% by mass to 70% by mass.

The positive electrode active material layer may further contain a conductive material. Thereby, the electroconductivity of a positive electrode active material layer can be improved.
The conductive material included in the positive electrode active material layer is not particularly limited as long as the conductivity of the positive electrode active material layer can be improved. For example, carbon black, graphite, acetylene black, ketjen black, carbon nanotube And carbon materials such as carbon fiber and mesoporous carbon. Moreover, although content of the electrically conductive material in a positive electrode active material layer changes with kinds of electrically conductive material, it is in the range of 1 mass%-10 mass% normally.

  The positive electrode active material layer may further contain a binder. Examples of the binder include polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). Further, the content of the binder in the positive electrode active material layer may be an amount that can fix the positive electrode active material or the like, and is preferably smaller. The content of the binder is preferably selected as appropriate according to the use of the sulfide-based solid electrolyte battery, but is usually in the range of 1% by mass to 10% by mass.

  The thickness of the positive electrode active material layer used in the present invention varies depending on the intended use of the sulfide-based solid electrolyte battery, but is preferably in the range of 5 μm to 250 μm, particularly 20 μm to 200 μm. It is preferable to be within the range.

The positive electrode current collector used in the present invention is not particularly limited as long as it has a function of collecting the positive electrode active material layer. Therefore, it is not always necessary to be directly electrically connected to the positive electrode active material layer, and even if it is indirectly connected to the positive electrode active material layer, it performs the function of collecting current from the positive electrode active material layer. Any conductor that constitutes the charge / discharge path is included in the “positive electrode current collector” in the present invention.
Examples of the material for the positive electrode current collector include aluminum, SUS, nickel, iron, and titanium. Of these, aluminum and SUS are preferable. Moreover, as a shape of a positive electrode electrical power collector, foil shape, plate shape, mesh shape etc. can be mentioned, for example, Foil shape is preferable.

(Negative electrode)
The negative electrode used in the present invention includes a negative electrode active material layer containing a negative electrode active material, and preferably includes a negative electrode current collector and a negative electrode lead directly connected to the negative electrode current collector.
In addition to the negative electrode active material, the negative electrode active material layer may contain at least one of an electrolyte, a conductive material, and a binder as necessary. In particular, in the present invention, the electrolyte is preferably the sulfide solid electrolyte described above. This is because a solid electrolyte battery with an extremely small amount of hydrogen sulfide generation can be obtained.

  The negative electrode active material used for the negative electrode active material layer is not particularly limited as long as it can absorb and release metal ions. When lithium ions are used as the metal ions, for example, metal materials such as lithium metal, lithium alloy, metal oxide, metal sulfide, metal nitride, and graphite can be used. The negative electrode active material may be in the form of a powder or a thin film.

The negative electrode active material layer may further contain an electrolyte, a conductive material, a binder, and the like. As the electrolyte, the conductive material, and the binder contained in the negative electrode active material layer, the same materials that can be used in the positive electrode active material described above can be used.
The film thickness of the negative electrode active material layer is not particularly limited, but is preferably in the range of 5 μm to 150 μm, and particularly preferably in the range of 10 μm to 80 μm.

  As the material and shape of the negative electrode current collector, the same materials and shapes as those of the positive electrode current collector described above can be employed.

(Electrolyte layer)
The electrolyte layer used in the present invention performs metal ion exchange between the positive electrode active material and the negative electrode active material described above. As the electrolyte that can be used in the electrolyte layer, the above-described sulfide-based solid electrolyte is used. The method for forming the electrolyte layer is not particularly limited, and examples thereof include a method for compression-molding the sulfide solid electrolyte powder.
The thickness of the electrolyte layer is not particularly limited, but is preferably in the range of 1 μm to 500 μm, for example, and particularly preferably in the range of 10 μm to 100 μm.
Moreover, it is preferable that the outer periphery of the electrolyte layer is covered with the water repellent coat described above.

(Other components)
As another component, a separator can be used for a sulfide-based solid electrolyte battery. The separator is disposed between the positive electrode current collector and the negative electrode current collector described above, and usually has a function of preventing the contact between the positive electrode active material layer and the negative electrode active material layer and holding the electrolyte layer. Have. Furthermore, as for the separator, examples of the material of the separator include resins such as polyethylene (PE), polypropylene (PP), polyester, cellulose, and polyamide. Among these, polyethylene and polypropylene are preferable. The separator may have a single layer structure or a multilayer structure. Examples of the separator having a multilayer structure include a separator having a two-layer structure of PE / PP and a separator having a three-layer structure of PP / PE / PP. Furthermore, in the present invention, the separator may be a nonwoven fabric such as a resin nonwoven fabric or a glass fiber nonwoven fabric. Moreover, the film thickness of the said separator is not specifically limited, It is the same as the film thickness of the separator used for a general sulfide type solid electrolyte battery.
Moreover, the battery case which accommodates a sulfide type solid electrolyte battery can also be used as another component. The shape of the battery case is not particularly limited as long as it can accommodate the above-described positive electrode, negative electrode, electrolyte layer, and the like. Specifically, a cylindrical shape, a square shape, a coin shape, a laminate shape, etc. Can be mentioned.

  The sulfide-based solid electrolyte battery of the present invention may be a primary battery or a secondary battery, but among them, a secondary battery is preferable. This is because it can be repeatedly charged and discharged and is useful, for example, as an in-vehicle battery.

  The method for producing the sulfide-based solid electrolyte battery of the present invention is not particularly limited as long as it is a method capable of obtaining the sulfide-based solid electrolyte battery described above. The sulfide-based solid electrolyte battery of the present invention can be obtained, for example, by performing a general method for producing a solid electrolyte battery using an electrolyte layer covered with a water-repellent coat. Specifically, the material constituting the positive electrode current collector, the material constituting the positive electrode active material layer, the electrolyte layer covered with the water repellent coating, the material constituting the negative electrode active material layer, and the negative electrode current collector are constituted. A method of producing a power generation element by sequentially pressing the materials, housing the power generation element inside the battery case, and caulking the battery case can be exemplified. Moreover, in this invention, the positive electrode, the negative electrode, and the electrolyte layer which each contain the said sulfide type solid electrolyte and have the said water-repellent coat on the surface can also be provided.

The sulfide-based solid electrolyte may be contained not only in the electrolyte layer but also in the positive electrode and / or the negative electrode, particularly in the case of the positive electrode in the positive electrode active material layer and in the case of the negative electrode in the negative electrode active material layer. It is preferable that the sulfide-based solid electrolyte is included.
In addition, when the positive electrode and / or the negative electrode contains a sulfide-based solid electrolyte, not only the outer periphery of the electrolyte layer but also the outer periphery of the positive electrode and / or the negative electrode containing the sulfide-based solid electrolyte is a water repellent coating. It is preferably coated.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, unless otherwise noted, all operations are carried out in an Ar gas filled glove box, and all solvents and dispersants used are subjected to static dehydration for 48 hours using molecular sieves. All were degreased several times with acetone before use and then vacuum dried at 120 ° C. for 24 hours.

[Example 1]
Lithium sulfide (Li ₂ S) and phosphorus pentasulfide (P ₂ S ₅ ) were used as starting materials for the sulfide-based solid electrolyte. These powders were weighed to a molar ratio of Li ₂ S: P ₂ S ₅ = 75: 25, mixed in an agate mortar, and then planetary ball mill (45 ml container made of zirconia, zirconia balls φ = 10 mm × 10). , at a rotational speed 370 rpm, for 40 hours mechanical milling, the inner 100mg the pellets molding machine of an area of 1 cm ^2, and pelletized at a pressure of 5.1ton / cm ^2. The surface of the pelleted sulfide-based solid electrolyte was coated with EGC-1700 (manufactured by Sumitomo 3M Limited) and dried in an Ar gas filled glove box with a dew point of -70 ° C. for 1 hour, whereby the sulfide of Example 1 A physical solid electrolyte layer was prepared.

[Comparative Example 1]
A sulfide-based solid electrolyte layer was produced in the same manner as in Example 1 except that the surface was not coated with EGC-1700.

[Comparative Example 2]
Instead of coating the surface with EGC-1700, a sulfide-based solid electrolyte layer was produced in the same manner as in Example 1 except that heptane (manufactured by Kanto Chemical Co., Ltd., dehydrated heptane) was applied to the surface.

[Comparative Example 3]
Lithium sulfide (Li ₂ S) and dialuminum trisulfide (Al ₂ S ₃ ) were used as starting materials for the sulfide-based solid electrolyte. These powders were weighed so as to have a molar ratio of Li ₂ S: Al ₂ S ₃ = 75: 25, mixed in an agate mortar, and then planetary ball mill (45 ml container made of zirconia, zirconia balls φ = 10 mm × 10). , at a rotational speed 370 rpm, for 40 hours mechanical milling, the inner 100mg the pellets molding machine of an area of 1 cm ^2, and pelletized at a pressure of 5.1ton / cm ^2. The surface of the pelleted sulfide-based solid electrolyte was coated with EGC-1700 (manufactured by Sumitomo 3M Co., Ltd.) and dried in an Ar gas-filled glove box with a dew point of -70 ° C. for 1 hour. A physical solid electrolyte layer was prepared.

[Comparative Example 4]
A sulfide-based solid electrolyte layer was prepared in the same manner as in Comparative Example 3 except that the surface was not coated with EGC-1700.

[Evaluation]
The sulfide-based solid electrolyte layer obtained in each Example and Comparative Example was placed in a 1755 cc desiccator, and the amount of hydrogen sulfide generated was measured by a hydrogen sulfide sensor (manufactured by Riken Keiki Co., Ltd., GX-2009). The measurement was performed in an air atmosphere at a temperature of 25 ° C. and a humidity of 50%.

FIG. 3 shows the amount of hydrogen sulfide generated in 300 seconds after the sulfide-based solid electrolyte layer obtained in Example 1, Comparative Example 1 and Comparative Example 2 was placed in an air atmosphere (after exposure to the atmosphere). The hydrogen sulfide generation amount in 300 seconds after exposure of the sulfide-based solid electrolyte layer obtained in Comparative Example 2 and Comparative Example 3 to the atmosphere is shown.
In Example 1, Comparative Example 1 and Comparative Example 2, 75Li ₂ S25P ₂ S ₅ having deliquescent properties was used as a starting material for the sulfide-based solid electrolyte, and the surface of Comparative Example 1 was not subjected to water-repellent coating. The sulfide-based solid electrolyte layer and the sulfide-based solid electrolyte layer of Comparative Example 2 wetted with a heptane solvent having no water-repellent component were the sulfide of Example 1 whose surface was water-repellent coated using EGC-1700. Compared with the system solid electrolyte layer, the amount of hydrogen sulfide generated in 300 seconds after exposure to the atmosphere was 1.4 times. This is because, in Example 1, the sulfide-based solid electrolyte deliquescent by reacting with moisture in the atmosphere was driven out of the sulfide-based solid electrolyte layer by the water-repellent coating, so that the liquefied material entered the electrolyte layer. This is probably because hydrogen sulfide generation due to the continuous reaction between the electrolyte layer and moisture was suppressed.
On the other hand, in Comparative Example 3 and Comparative Example 4, 75Li ₂ S25Al ₂ S ₃ having no deliquescence was used as a starting material for the sulfide-based solid electrolyte, and the surface was water-repellent coated using EGC-1700. 3 and the sulfide solid electrolyte of Comparative Example 4 that was not coated with water repellent coating, the difference in the amount of hydrogen sulfide generated in 300 seconds after exposure to the atmosphere was 0% of the total amount of hydrogen sulfide generated. The amount was 1% and there was no significant difference.
Therefore, the sulfide-based solid electrolyte battery of the present invention repels a sulfide-based solid electrolyte that has been deliquescent by reacting with moisture in the atmosphere because the outer periphery of the sulfide-based solid electrolyte layer is coated with a water-repellent coating. It is expelled out of the water coat, and the reaction between the sulfide solid electrolyte layer and moisture and the generation of hydrogen sulfide due to the reaction can be suppressed.

DESCRIPTION OF SYMBOLS 1 Electrolyte layer 2 Positive electrode active material layer 3 Negative electrode active material layer 4 Positive electrode collector 5 Negative electrode collector 6 Positive electrode 7 Negative electrode 8 Water repellent coating 10 Sulfide-based solid electrolyte battery

Claims (4)

A solid electrolyte battery comprising at least a positive electrode, a negative electrode, and a sulfide-based solid electrolyte layer interposed between the positive electrode and the negative electrode;
At least a part of the outer periphery of the sulfide-based solid electrolyte layer is covered with a water repellent coat containing a water repellent,
When the sulfide-based solid electrolyte layer comes into contact with moisture and is liquefied, the liquefied sulfide-based solid electrolyte can be put out on the surface of the water-repellent coat opposite to the sulfide-based solid electrolyte layer. A sulfide-based solid electrolyte battery.   The sulfide-based solid electrolyte battery according to claim 1, wherein a contact angle of water with respect to the water repellent coat is 70 ° or more.   The sulfide system according to claim 1 or 2, wherein the water repellent is a water repellent selected from the group consisting of a fluororesin-containing water repellent, a fluoroalkyl group-containing silane compound, and a dimethyl silicone water repellent. Solid electrolyte battery. The sulfide-based solid electrolyte is selected from the group consisting of Li ₂ S—SiS ₂ system, Li ₂ S—P ₂ S ₅ system, Li ₂ S—GeS ₂ system, and Li ₂ S—B ₂ S ₃ system. The sulfide-based solid electrolyte battery according to any one of claims 1 to 3, which is a sulfide-based solid electrolyte.

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