JP6278301B2 - Thin-film sulfur-coated activated carbon manufacturing method, thin-film sulfur-coated activated carbon, positive electrode mixture and all-solid-state lithium-sulfur battery - Google Patents

Description

The present invention relates to a method for producing a thin film sulfur-coated activated carbon, a thin film sulfur-coated activated carbon, a positive electrode mixture, and an all solid-state lithium sulfur battery.

Sulfur is known to have a very high theoretical capacity of about 1672 mAh / g, and lithium sulfur batteries using sulfur as a positive electrode active material have been actively studied.
Lithium-sulfur batteries are roughly classified into liquid lithium-sulfur batteries that use liquid electrolytes as electrolytes and all-solid-state lithium-sulfur batteries that use solid electrolytes.

In the liquid type lithium-sulfur battery, lithium polysulfide produced by the reaction between lithium ions and sulfur is dissolved in the electrolyte solution, which adversely affects the charge / discharge capacity and life of the battery. In order to improve this problem, a liquid lithium sulfur battery using a cathode electrode including a porous conductive material coated with sulfur has been disclosed (Patent Document 1).

On the other hand, the all-solid-state lithium-sulfur battery is suitable for maintaining the charge / discharge capacity of the battery and extending its life because there is no problem that lithium polysulfide dissolves into the electrolyte solution. In addition, because it does not contain a flammable organic solvent, there is no risk of liquid leakage or ignition, and safety can be ensured. In addition, an all-solid-state lithium-sulfur battery is better than a liquid-type lithium-sulfur battery because it does not require a separator. preferable.

However, in the conventional all-solid-state lithium-sulfur battery, since the positive electrode active material sulfur is electrically insulating, the inside of the sulfur particles or the sulfur film has poor lithium ion conductivity and electronic conductivity, and the battery is sufficiently charged. There was a problem that no reaction (redox reaction) occurred.

JP 2003-197196 A

The present invention provides a method for producing a thin-film sulfur-coated activated carbon that can be suitably used for a positive electrode mixture of an all-solid-state lithium-sulfur battery having excellent discharge capacity and rate characteristics by making the best use of the excellent physical properties of sulfur. The purpose is to provide. Another object of the present invention is to provide a thin-film sulfur-coated activated carbon produced by the production method, a positive electrode mixture containing the thin-film sulfur-coated activated carbon, and an all-solid-state lithium-sulfur battery including a positive electrode mixture layer containing the positive electrode mixture. And

As a result of intensive studies, the present inventors have found that a thin-film sulfur-coated activated carbon obtained by coating activated carbon having a BET specific surface area of 1800 m ² / g or more with sulfur having a film thickness of 0.2 to 1.4 nm has an excellent discharge capacity. The present invention was completed by finding a suitable method for producing such a thin-film sulfur-coated activated carbon by finding out that it is suitable for a positive electrode mixture of a solid-state lithium-sulfur battery.

The method for producing the thin film sulfur-coated activated carbon of the present invention is as follows.
A step of immersing activated carbon having a BET specific surface area of 1800 m ² / g or more in a sulfur solution and coating the activated carbon with sulfur (a); and
An all-solid-state lithium-sulfur battery coated with sulfur having a film thickness of 0.2 to 1.4 nm, comprising the step (b) of separating the activated carbon coated with sulfur obtained in step (a) from the sulfur solution. It is a manufacturing method of the thin film sulfur covering activated carbon for positive electrode compound materials.

It is preferable that the manufacturing method of a thin film sulfur covering activated carbon further includes the process (c) which heat-processes the activated carbon coat | covered with sulfur isolate | separated in the process (b).

In the method for producing a thin film sulfur-coated activated carbon, the temperature of the heat treatment in the step (c) is preferably 60 ° C. or higher, and more preferably 100 ° C. or higher.

In the method for producing a thin film sulfur-coated activated carbon, the film thickness is preferably 0.5 to 1.0 nm.

The thin film sulfur-coated activated carbon of the present invention is produced by the method for producing a thin film sulfur-coated activated carbon of the present invention.

The positive electrode mixture of the present invention is used for an all-solid-state lithium-sulfur battery, and includes the thin film sulfur-coated activated carbon of the present invention and a solid electrolyte.

The all-solid-state lithium-sulfur battery of the present invention includes a positive electrode mixture layer including the positive electrode mixture of the present invention, a solid electrolyte layer, a negative electrode, and a current collector.

In the method for producing a thin film sulfur-coated activated carbon of the present invention, an activated carbon having a BET specific surface area of 1800 m ² / g or more is coated with sulfur through a predetermined process. A thin-film sulfur-coated activated carbon that is uniformly coated can be easily produced.
Moreover, the thin film sulfur covering activated carbon of this invention manufactured with the manufacturing method of this invention has the characteristic that the spreading | diffusion of an electron and lithium ion occurs easily in the sulfur inside. Therefore, by using the thin film sulfur-coated activated carbon for the positive electrode mixture of the all-solid-state lithium-sulfur battery, it is possible to provide an all-solid-state lithium-sulfur battery having a large discharge capacity per positive electrode mixture layer and excellent rate characteristics.
Moreover, since the positive electrode mixture of the present invention uses thin-film sulfur-coated activated carbon, it is suitable for forming a positive electrode mixture layer having a large discharge capacity and excellent rate characteristics.
Furthermore, since the all-solid-state lithium-sulfur battery of the present invention includes the positive electrode mixture layer using the positive electrode mixture of the present invention, it is excellent in discharge capacity and rate characteristics.

It is sectional drawing which represented typically an example of embodiment of the all-solid-state lithium sulfur battery of this invention.

<< Production Method of Thin Film Sulfur-Coated Activated Carbon >>
First, the manufacturing method of the thin film sulfur covering activated carbon of this invention is demonstrated.
The method for producing the thin film sulfur-coated activated carbon of the present invention is as follows.
A step of immersing activated carbon having a BET specific surface area of 1800 m ² / g or more in a sulfur solution and coating the activated carbon with sulfur (a); and
Separating the activated carbon coated with sulfur obtained in step (a) from the sulfur solution;
It is a manufacturing method of the thin film sulfur covering activated carbon for positive electrode mixtures of the all-solid-state lithium-sulfur battery covered with sulfur with a film thickness of 0.2 to 1.4 nm.

<Process (a)>
In the production method of the present invention, first, the step (a) of immersing activated carbon having a BET specific surface area of 1800 m ² / g or more in a sulfur solution and coating the activated carbon with sulfur is performed. Therefore, a sulfur solution is first prepared. The sulfur solution is not particularly limited as long as sulfur is dissolved in a solvent, and examples of the solvent include cyclohexane, n-hexane, toluene, xylene, carbon disulfide, and the like. These solvents may be used alone or in combination of two or more.

Among these solvents, it is preferable to use a solvent having a sulfur solubility of 1 to 10% by weight at the operating temperature. In a solvent having a solubility of less than 1% by weight, the amount of sulfur covering the activated carbon may be reduced. On the other hand, in a solvent having a solubility of more than 10% by weight, sulfur is very easily dissolved in the solvent, and the activated carbon is relatively This is because the amount of sulfur covering the activated carbon may be reduced. Considering these matters, the solubility of sulfur at the operating temperature differs depending on the type of sulfur (single sulfur or sulfur-containing compound), but it cannot be generally stated, but it is preferable to use cyclohexane as the solvent. In addition, as the sulfur solution, a sulfur solution obtained by dissolving sulfur in a heated solvent in order to increase the solubility of sulfur may be used, or a sulfur solution obtained by dissolving sulfur in the solvent is heated. A thing may be used.

Moreover, as sulfur used for preparation of a sulfur solution, single-piece | unit sulfur may be used and a sulfur containing compound may be used.
Examples of the sulfur-containing compound is not particularly limited, for _example, lithium polysulphides such as _{Li 2 S 8, Li 2 S} 4, Li 2 S 2, may be used lithium sulfide _(Li 2 S) and the like. These compounds may be used alone or in combination of two or more, and may be used in combination with single sulfur.

In the step (a), activated carbon having a BET specific surface area of 1800 m ² / g or more is immersed in a sulfur solution, and the activated carbon is covered with sulfur. Activated carbon functions as an electron conductor in the positive electrode mixture of the all-solid-state lithium-sulfur battery.
The activated carbon has a BET specific surface area of 1800 m ² / g or more. When the BET specific surface area is less than 1800 m ² / g, the amount of sulfur covering the surface of the activated carbon is small, and as a result, when used for the positive electrode mixture, the filling rate of sulfur in the positive electrode mixture becomes low. It is. The BET specific surface area is preferably 2400 m ² / g or more, and more preferably 2900 or more. In addition, although the upper limit of a BET specific surface area is not specifically limited, For example, it is 3500 m < ² > / g.

In this specification, the BET specific surface area refers to a specific surface area determined by the Brenauer-Emmet-Telle (BET) method. Specifically, an activated carbon sample is adsorbed with nitrogen gas at a liquid nitrogen temperature. The specific surface area determined using the nitrogen adsorption isotherm obtained in this way. As a measuring device for obtaining the BET specific surface area, for example, an automatic specific surface area / pore distribution measuring device (BELSORP-miniII manufactured by Nippon Bell Co., Ltd.) can be used.

In the step (a), the weight ratio between the activated carbon and the sulfur solution when immersing the activated carbon was a solvent having a sulfur solubility of 1 to 10% by weight at the use temperature as described above as the solvent of the sulfur solution. In some cases, 1:10 to 1: 1000 is preferred. The reason is that if the amount of the sulfur solution is less than 1:10, the sulfur adsorption amount may be insufficient. On the other hand, even if the sulfur solution is increased from 1: 1000, the sulfur adsorption amount is hardly changed, and the sulfur solution is wasted.

In the step (a), the liquid temperature and the immersion time of the sulfur solution when immersing the activated carbon are not particularly limited, but the liquid temperature is higher than the melting point of the solvent used and in the range below the boiling point, and the immersion time is 10 minutes. It is preferably ~ 500 hours. If the liquid temperature is lower than the melting point of the solvent, it may freeze, while if the temperature is higher than the boiling point of the solvent, there is no advantage such as higher solubility of sulfur. If the immersion time is less than 10 minutes, the amount of sulfur covered may be insufficient. On the other hand, if the time exceeds 500 hours, the amount of sulfur covered will not increase any more.

Further, in the step (a), treatments such as ultrasonic treatment and stirring treatment may be performed as necessary while immersing the activated carbon. This is because the entire activated carbon can be more reliably and uniformly coated with sulfur. Although the conditions of ultrasonic treatment are not specifically limited, For example, it can carry out for 1 to 500 minutes on conditions with an oscillation frequency of 20-50 Hz. The stirring treatment is not particularly limited, but for example, using a magnetic stirrer, mechanical stirrer, shaker or the like, the stirring process is performed at a temperature range higher than the melting point of the solvent used and lower than the boiling point for 10 minutes to 500 hours. Can do.

In addition, in order to increase the amount of sulfur covered, in step (a), the temperature is initially increased to increase the concentration of the sulfur solution, and as the concentration of the sulfur solution decreases with the adsorption of sulfur to the activated carbon. The temperature may be gradually lowered while taking care not to exceed the saturation concentration of sulfur.

In the present invention, “cover” means that sulfur adheres to a portion where nitrogen gas is adsorbed when the specific surface area is measured by the BET method.

<Step (b)>
Next, in the production method of the present invention, the step (b) of separating the sulfur-coated activated carbon obtained in the step (a) from the sulfur solution is performed. In the step (b), a method for separating the activated carbon covered with sulfur from the sulfur solution is not particularly limited, and known methods such as filtration, centrifugation, and decantation can be used. Although it does not specifically limit as filtration, For example, natural filtration, suction filtration (vacuum filtration), pressure filtration, centrifugal filtration, etc. are employable. Through the step (b), activated carbon coated with sulfur (thin film sulfur-coated activated carbon) can be obtained.

<Step (c)>
In the manufacturing method of this invention, it is preferable to perform the process (c) which heat-processes the activated carbon coat | covered with sulfur isolate | separated in the process (b). This is because the solvent remaining on the activated carbon coated with sulfur can be more reliably removed by performing the step (c). Moreover, the sulfur covering the activated carbon can be firmly adhered to the activated carbon, and the resistance at the solid interface (resistance between sulfur and activated carbon) can be reduced. In the step (c), a plurality of heat treatments may be performed step by step while changing temperature conditions.

The heat treatment of the activated carbon covered with sulfur in the step (c) is not particularly limited, and can be performed, for example, in an atmosphere of argon, nitrogen, air, or the like for 1 second to 50 hours. Moreover, you may carry out under reduced pressure on the conditions which sulfur does not sublime. The temperature of the heat treatment (in the step (c), when the heat treatment is performed a plurality of times step by step while changing the temperature condition) is not particularly limited, but is preferably 60 ° C. or higher. More preferably, the temperature is 100 ° C. or higher. If the temperature is lower than 60 ° C., the above-mentioned interface resistance reduction effect may not be enjoyed. Although the upper limit of the temperature of heat processing is not specifically limited, It is preferable to set it as 250 degreeC. The reason is that, even if the temperature is higher than 250 ° C., the above-described interface resistance reduction effect is not further improved, so that the energy required for heating is wasted. In addition, what is necessary is just to perform heat processing using a conventionally well-known drying apparatus, specifically, for example, using a constant temperature dryer, a ventilation dryer, a vacuum dryer, an infrared dryer, etc.

In the thin film sulfur-coated activated carbon, the film thickness of sulfur is 0.2 to 1.4 nm. When the film thickness is thinner than 0.2 nm, the amount of sulfur in the thin film sulfur-coated activated carbon is reduced, and the filling rate of sulfur with respect to the positive electrode mixture is lowered. On the other hand, if the film thickness exceeds 1.4 nm, the diffusion resistance inside sulfur increases, and the discharge capacity may decrease or the rate characteristics may deteriorate. The film thickness is preferably 0.5 to 1.0 nm. In addition, what is necessary is just to calculate the film thickness of sulfur based on the weight of each of the activated carbon and sulfur which occupy in thin film sulfur covering activated carbon, and the BET specific surface area and sulfur specific gravity of activated carbon.

In the production method of the present invention, the film thickness of sulfur is controlled by adjusting the type and amount of activated carbon, the type and amount of solvent, the concentration and temperature of the sulfur solution, the immersion time of the activated carbon in the sulfur solution, the stirring conditions, and the like. can do.

In the thin film sulfur-coated activated carbon, the sulfur content in the thin film sulfur-coated activated carbon is preferably 50 to 93% by weight, and more preferably 70 to 90% by weight. When the content exceeds 93% by weight, the sulfur film becomes thick and the diffusion resistance inside the sulfur may become too high. On the other hand, when the content is less than 50% by weight, the amount of sulfur decreases and the positive electrode mixture. It is because the filling rate of sulfur inside may become low.

According to the production method of the present invention, it is possible to produce a thin film sulfur-coated activated carbon in which activated carbon having a BET specific surface area of 1800 m ² / g or more is uniformly coated with sulfur having a film thickness of 0.2 to 1.4 nm. Moreover, the thin film sulfur covering activated carbon manufactured by the manufacturing method of this invention is also one of this invention. Thin-film sulfur-coated activated carbon has the property that electrons and lithium ions in sulfur can easily diffuse. Therefore, by using thin-film sulfur-coated activated carbon for the positive electrode mixture of all-solid-state lithium-sulfur batteries, An all-solid-state lithium-sulfur battery having a large discharge capacity and excellent rate characteristics can be provided.

<< Positive electrode mixture >>
Next, the positive electrode mixture of the present invention will be described.
The positive electrode mixture of the present invention is a material for forming a positive electrode mixture layer, which is used for an all-solid-state lithium-sulfur battery including a thin film sulfur-coated activated carbon and a solid electrolyte produced by the production method of the present invention. is there.

In the positive electrode mixture, the content of the thin film sulfur-coated activated carbon is not particularly limited, but is preferably 40 to 80% by weight in the positive electrode mixture. When the content is less than 40% by weight, the filling rate of sulfur in the positive electrode mixture may be low, and the discharge capacity per positive electrode mixture layer may be reduced. On the other hand, when the content exceeds 80% by weight When the solid electrolyte filling rate is lowered, the ionic conductivity of the positive electrode mixture layer is lowered, and the discharge capacity per positive electrode mixture layer may be reduced.

<Solid electrolyte>
The solid electrolyte is not particularly limited, and for example, a polymer solid electrolyte such as a polyethylene oxide polymer compound, a polymer compound containing at least one of a polyorganosiloxane chain and a polyoxyalkylene chain, and the like can be used. Moreover, inorganic solid electrolytes, such as a sulfide type solid electrolyte and / or an oxide type solid electrolyte, can be used.
As the oxide solid electrolyte, for example, an inorganic solid electrolyte containing at least one of phosphorus and oxygen and lithium can be suitably used. More specifically, for example, Li ₂ O—P ₂ O ₅ , Li ₂ O—SiO ₂ , Li ₂ O—Nb ₂ O ₅ , Li ₂ O—P ₂ O ₅ —SiO ₂ , Li ₂ O—SiO _{2 -B 2 O 3, Li 2} O-Al 2 O 3 -GeO 2 -P 2 O 5, Li 2 O-Al 2 O 3 -TiO 2 -P 2 O 5 or the like can be used.
As the sulfide-based solid electrolyte, for example, an inorganic solid electrolyte containing at least one of phosphorus and sulfur and lithium can be preferably used. More specifically, for _{example, Li 2 S-P 2 S} 5, Li 2 S-P 2 S 5 -P 2 O 5, Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li ₂ S—SiS ₂ —LiSiO ₄ or the like can be used.
These solid electrolytes may be used alone or in combination of two or more.

The content of the solid electrolyte is not particularly limited, but is preferably 20 to 60% by weight in the positive electrode mixture. When the content is less than 20% by weight, the lithium ion conductivity in the positive electrode mixture layer is lowered, and the discharge capacity per positive electrode mixture layer may be reduced, or the rate characteristics may be deteriorated. When the content exceeds 60% by weight, the filling rate of sulfur in the positive electrode mixture is lowered, and the discharge capacity per positive electrode mixture layer may be reduced.

The positive electrode mixture may contain optional components such as a binder and a solvent as necessary.

<Binder>
Although it does not specifically limit as a binder, A thermoplastic resin, a thermosetting resin, etc. can be used, for example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber, tetra Fluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, Vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer (ETFE resin), polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoro Propylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethyl vinyl ether -Tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer, etc. are mentioned. These binders may be used alone or in combination of two or more. Although content of a binder is not specifically limited, It is preferable that it is 0.01 to 10 weight% in a positive electrode compound material.

<Solvent>
The solvent is not particularly limited, and examples thereof include amine solvents such as N, N-dimethylaminopropylamine and diethylenetriamine, ether solvents such as tetrahydrofuran, ketone solvents such as methyl ethyl ketone, ester solvents such as methyl acetate, dimethyl Examples thereof include amide solvents such as acetamide and 1-methyl-2-pyrrolidone, and hydrocarbon solvents such as toluene, xylene, n-hexane and cyclohexane. These solvents may be used alone or in combination of two or more. Although content of a solvent is not specifically limited, It is preferable that it is 10 to 99 weight% in a positive electrode compound material. By using a positive electrode mixture containing a solvent, the positive electrode mixture layer can be easily produced. The solvent is removed by drying after the production of the positive electrode mixture layer.

<Method for producing positive electrode mixture>
The positive electrode mixture can be obtained by mixing a thin film sulfur-coated activated carbon and a solid electrolyte, and further, if necessary, optional components such as a binder and a solvent. A method for mixing these is not particularly limited, and a conventionally known method can be used. For example, planetary ball mill (manufactured by Fritsch), hybridization system (manufactured by Nara Machinery Co., Ltd.), cosmos (manufactured by Kawasaki Heavy Industries, Ltd.) ), Mechano-fusion system (manufactured by Hosokawa Micron Corporation), mechano mill (manufactured by Okada Seiko Co., Ltd.), theta composer (manufactured by Tokusu Kosakusho Co., Ltd.), nanosonic mill (manufactured by Inoue Seisakusho Co., Ltd.), kneader (manufactured by Inoue Seisakusho Co., Ltd.), super mass collider (Masuyuki Industrial Co., Ltd.), Nanomec Reactor (Techno Eye Co., Ltd.), Cornell Despa (Asada Iron Works Co., Ltd.), Planetary Mixer (Asada Iron Works Co., Ltd.) and the like.

In the production of the positive electrode mixture, it is preferable to perform heat treatment after mixing the respective components. This is because the contact interface between sulfur, activated carbon and solid electrolyte contained in the positive electrode mixture can be strengthened, and the interface resistance can be reduced. What is necessary is just to perform heat processing on the conditions similar to the heat processing conditions of the process (c) in the manufacturing method of the thin film sulfur covering activated carbon of this invention.

Such heat treatment is performed when the thin film sulfur-coated activated carbon produced without performing the step (c) in the above-described method for producing the thin film sulfur-coated activated carbon is used as the thin film sulfur-coated activated carbon used for the production of the positive electrode mixture. Is particularly preferred. This is because the effect of heat treatment at the time of producing the positive electrode mixture, that is, the effect of reducing the interfacial resistance of sulfur, activated carbon, and solid electrolyte contained in the positive electrode mixture can be particularly remarkably enjoyed.

<< All solid-state lithium-sulfur battery >>
Next, the all solid-state lithium-sulfur battery of the present invention will be described with reference to the drawings.
The all-solid-state lithium-sulfur battery of the present invention is an all-solid-state lithium-sulfur battery including a positive electrode mixture layer including the positive electrode mixture of the present invention, a solid electrolyte layer, a negative electrode, and a current collector.

In the present specification, the “all solid type” means a polymer solid electrolyte and / or an inorganic solid electrolyte as an electrolyte, and contains substantially no solvent in the negative electrode, the solid electrolyte layer, and the positive electrode mixture layer. Say things. Further, in the present specification, “substantially does not contain a solvent” means that a trace amount of the solvent may remain.

FIG. 1 is a cross-sectional view schematically showing an example of an embodiment of an all solid-state lithium-sulfur battery.
As shown in FIG. 1, an all-solid-state lithium-sulfur battery 10 includes a negative electrode 2, a solid electrolyte layer 3, and a positive electrode mixture layer 4 that are stacked in order, and current collectors (negative electrode current collector 1 and positive electrode current collector) on both sides thereof. It has a structure in which the body 5) is arranged.
Hereinafter, each of the current collector (negative electrode current collector, positive electrode current collector), negative electrode, solid electrolyte layer, and positive electrode mixture layer will be described in order.

<Current collector>
Although it does not specifically limit as a collector, For example, Al, Cu, Ni, stainless steel, etc. can be used. As the negative electrode current collector, Cu is preferably used because it is difficult to make an alloy with lithium and it can be easily processed into a thin film. As the positive electrode current collector, Al is preferably used because it is easy to process into a thin film and is inexpensive.

<Negative electrode>
The negative electrode is not particularly limited as long as it contains a material that absorbs and releases lithium ions as a negative electrode active material. Here, examples of the material that occludes and releases lithium ions include metallic lithium, lithium alloy, metal oxide, metal sulfide, and a carbonaceous substance that occludes and releases lithium ions.
Examples of the lithium alloy include alloys of lithium with aluminum, silicon, tin, magnesium, indium, calcium, and the like. Examples of the metal oxide include tin oxide, silicon oxide, lithium titanium oxide, niobium oxide, and tungsten oxide. Examples of the metal sulfide include tin sulfide and titanium sulfide. Examples of the carbonaceous material that absorbs and releases lithium ions include graphite, coke, mesophase pitch-based carbon fiber, spherical carbon, and resin-fired carbon.

The method for obtaining the negative electrode is not particularly limited, but a method of pressing a material that absorbs and releases lithium ions, a negative electrode precursor dispersion containing a material that absorbs and releases lithium ions and a solvent is applied to a negative electrode current collector, and then dried. The method of post-pressing etc. is mentioned. As the solvent contained in the negative electrode precursor dispersion, the same solvents as those used for the positive electrode mixture described above can be used. The solvent is used to assist the application of the negative electrode precursor dispersion and is removed by drying after the application.

<Solid electrolyte layer>
The solid electrolyte layer can be obtained by a method in which the solid electrolyte is pressure-molded, a method in which the solid electrolyte is dispersed in a solvent, and then applied and dried. When a solid electrolyte layer is obtained by these methods, heat treatment may be performed at an arbitrary timing for the purpose of reducing the interface resistance of the solid electrolyte layer and improving the denseness. The method for pressure forming the solid electrolyte is not particularly limited. For example, a method of sandwiching and pressing the solid electrolyte between a negative electrode current collector and a positive electrode current collector, a method of pressing with a jig of a pressure molding machine, etc. Is mentioned. When a solid electrolyte layer is obtained by a method in which the solid electrolyte is dispersed in a solvent and then applied and dried, the dried solid electrolyte layer may be pressed by the same method as described above.

<Positive electrode mixture layer>
The positive electrode mixture layer can be obtained by, for example, a method of supporting the positive electrode mixture on the positive electrode current collector, a method of pressure forming the positive electrode mixture, or the like. The method for supporting the positive electrode mixture on the positive electrode current collector is not particularly limited. For example, after applying the positive electrode mixture formed into a paste using an organic solvent or the like to the positive electrode current collector and drying, Examples thereof include a method of fixing by pressing. The method for applying the positive electrode mixture to the positive electrode current collector is not particularly limited, and examples thereof include a slit die coating method, a screen coating method, a curtain coating method, a knife coating method, a gravure coating method, and an electrostatic spray method. It is done. The method for pressure forming the positive electrode mixture is not particularly limited. For example, the method of pressing the positive electrode mixture between the negative electrode current collector and the solid electrolyte layer and the positive electrode current collector, and pressure forming The method of pressing with the jig of a machine is mentioned. When the positive electrode mixture layer is obtained by these methods, heat treatment may be performed at an arbitrary timing for the purpose of reducing the interface resistance of the positive electrode mixture layer and improving the denseness.

The all solid-state lithium-sulfur battery may have a separator in addition to the above-described negative electrode current collector, negative electrode, solid electrolyte layer, positive electrode mixture layer, and positive electrode current collector.

<Method for producing all solid-state lithium-sulfur battery>
Although the manufacturing method of an all-solid-type lithium sulfur battery is not specifically limited, For example, the following methods etc. are mentioned.
First, a solid electrolyte is sandwiched between a negative electrode current collector and a positive electrode current collector and pressed to produce a solid electrolyte layer. Next, the positive electrode current collector is once removed, the positive electrode mixture is deposited on one side of the solid electrolyte layer, and both ends of the positive electrode current collector (the negative electrode current collector on the solid electrolyte layer side and the positive electrode current collector on the positive electrode mixture side) The positive electrode mixture layer and the positive electrode current collector are laminated on one surface of the solid electrolyte layer, and the negative electrode current collector is laminated on the other surface of the solid electrolyte layer. Finally, once remove the negative electrode current collector, put the negative electrode on the side opposite to the positive electrode mixture layer side of the solid electrolyte layer, and further press the negative electrode current collector on the negative electrode side and press the other side of the solid electrolyte layer A negative electrode and a negative electrode current collector are stacked on the surface. Moreover, it may be pressed one layer at a time as described above, or two or more layers may be deposited, and a plurality of layers may be pressed together and laminated. By such a method, an all solid-state lithium-sulfur battery can be produced.

The shape of the all solid-state lithium-sulfur battery is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, and a rectangular type.

<Applications of all-solid-state lithium-sulfur batteries>
Although it does not specifically limit as a use of an all-solid-state type lithium sulfur battery, For example, it can use suitably for the electric products by which high energy density is requested | required, such as a hybrid vehicle and an electric vehicle.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

1. Raw materials used In the following examples and comparative examples, the following materials were used.
1-1. Positive electrode active material sulfur (manufactured by Aldrich, specific gravity 2 g / cm ³ )
1-2. Activated carbon activated carbon A (manufactured by Kansai Thermochemical Co., Ltd., BET specific surface area: 3000 m ² / g)
Activated carbon B (manufactured by Kansai Thermochemical Co., Ltd., BET specific surface area: 2500 m ² / g)
Activated carbon C (YP-80F manufactured by Kuraray Chemical Co., BET specific surface area: 1900 m ² / g)
Activated carbon D (manufactured by Kansai Thermochemical Co., Ltd., BET specific surface area: 1500 m ² / g)
1-3. Anode material lithium sheet (Furuuchi Chemical Co., Ltd., thickness 0.25 mm)
Indium sheet (Furuuchi Chemical Co., Ltd., thickness 0.30mm)
1-4. Organic solvent cyclohexane (made by Wako Pure Chemical Industries, special reagent grade) for the production of thin-film sulfur-coated activated carbon
1-5. Raw material lithium sulfide for production of solid electrolyte (manufactured by Furuuchi Chemical Co., Li ₂ S)
Phosphorus pentasulfide (manufactured by Aldrich, P ₂ S ₅ )

2. Production of Solid Electrolyte (Synthesis Example 1) Production of Solid Electrolyte A In a glove box (MDB-1KP type, manufactured by Miwa Seisakusho) in an argon atmosphere with a dew point temperature of −70 ° C. or lower, Li ₂ S and P ₂ S ₅ Weighed so that the total molar ratio of 40:60 was 2.0 g, and mixed in a mortar and 180 g of 4 mmφ zirconia balls in a zirconia container with 80 ml capacity (manufactured by Fritsch, for Premium line P-7). The solid electrolyte A was produced by processing with a planetary ball mill (Premium line P-7, manufactured by Fritsch) at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation) for 10 hours.

(Synthesis Example 2) Production of solid electrolyte B In a glove box (MDB-1KP type, manufactured by Miwa Seisakusho Co., Ltd.) in an argon atmosphere with a dew point temperature of −70 ° C. or less, Li ₂ S and P ₂ S ₅ were 80:20 Weighing so that the total molar ratio is 2.0 g and mixing in a mortar and 180 g of 4 mmφ zirconia balls are put in a zirconia container (Fritch company, Premium line P-7) with a capacity of 80 ml, and a planetary ball mill The solid electrolyte B was produced by processing for 10 hours at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation) with Fritsch (Premium line P-7).

3. Production Method of All Solid Type Lithium Sulfur Battery The battery production described below was performed in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or lower.
A cylindrical jig made of SUS304 (10 mmφ, height 10 mm) is inserted as a negative electrode current collector from the lower side of a cylindrical tube jig made of polycarbonate (inner diameter 10 mmΦ, outer diameter 23 mmΦ, height 20 mm). 70.0 mg of solid electrolyte A or B is put from the upper side of the tool, and a cylindrical jig made of SUS304 (10 mmΦ, height 15 mm) is further inserted as a positive electrode current collector from the upper side of the cylindrical pipe jig made of polycarbonate. Alternatively, B was sandwiched and pressed at a pressure of 200 MPa for 1 minute to produce a solid electrolyte layer having a diameter of 10 mmΦ and a thickness of about 0.6 mm.
Next, the cylindrical jig (positive electrode current collector) made of SUS304 inserted from the upper side is once extracted, 7.5 mg of the positive electrode mixture is put on the solid electrolyte layer in the polycarbonate cylindrical tube, and again made of SUS304 from the upper side. A cylindrical jig (positive electrode current collector) was inserted and pressed at 200 MPa for 3 minutes to form a positive electrode mixture layer having a diameter of 10 mmΦ and a thickness of about 0.1 mm.
Next, a cylindrical jig (negative electrode current collector) made of SUS304 inserted from the lower side is extracted, and a lithium sheet as a negative electrode is punched into a diameter of 8 mmΦ, and an indium sheet is punched into a diameter of 9 mmΦ with a punch. Are inserted from the lower side of the cylindrical tube jig made of polycarbonate, and the cylindrical jig made of SUS304 (negative electrode current collector) is inserted again from the lower side, and pressed at a pressure of 80 MPa for 3 minutes to form a lithium-indium alloy. A negative electrode was formed.
As described above, an all-solid-state lithium-sulfur battery in which the negative electrode current collector, the lithium-indium alloy negative electrode, the solid electrolyte layer, the positive electrode mixture layer, and the positive electrode current collector were stacked in this order from the bottom was produced.

4). Evaluation Method In the following examples and comparative examples, the following evaluations were performed.
(A) It measured using the BET specific surface area automatic specific surface area / pore distribution measuring apparatus (Nippon Bell Co., Ltd. make, BELSORP-mini II), and measured by BET method.
(B) Using a discharge capacity charge / discharge test apparatus (ACD-M01A, manufactured by Asuka Electronics Co., Ltd.), with a current value of 0.20 mA (0.25 mA / cm ² ), the cut-off voltage is 0.5 to 2.5 V. Then, charge and discharge were repeated, and the discharge capacity at the second cycle was measured.
The measured discharge capacity is the weight (g) of sulfur contained in the thin-film sulfur-coated activated carbon (a mixture of sulfur and activated carbon in Comparative Examples 2 to 4, 6, 7, and 9 to 11) in the positive electrode mixture. The numerical value obtained by dividing the value was taken as the discharge capacity per sulfur, and the value obtained by dividing by the weight of the positive electrode mixture layer (0.015 g) was taken as the discharge capacity per positive electrode mixture layer.
In Table 1 below, there are several examples in which the discharge capacity per sulfur is higher than the theoretical capacity of about 1672 mAh / g. This is because the solid electrolyte A or B in the positive electrode mixture is present. It is considered that a part of lithium sulfide (Li ₂ S) remaining in the metal works as a positive electrode active material.

(Comparative Example 1)
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, 1000 mg of activated carbon A was immersed in this cyclohexane solution of sulfur and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon A. Subsequently, the activated carbon A was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon A.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and the activated carbon coated with sulfur was settled by centrifugation, and the solid content of the supernatant sulfur solution was measured and found to be 0.990 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 800 mg of sulfur coats 1000 mg of activated carbon A. Therefore, sulfur in the activated carbon coated with sulfur is 44.4 wt% (Table 1). Since the activated carbon A used has a BET specific surface area of 3000 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a film thickness of 0.13 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 1589 mg (yield 88.3%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 148 mg (yield 74.0%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

Example 1
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, 600 mg of activated carbon A was immersed in this cyclohexane solution of sulfur and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon A. Subsequently, the activated carbon A was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon A.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and the activated carbon coated with sulfur was sedimented by centrifugation, and the solid content of the supernatant sulfur solution was measured and found to be 0.892 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 820 mg of sulfur coats 600 mg of activated carbon A. Therefore, the sulfur in the activated carbon coated with sulfur is 57.7 wt% (Table 1). Since the activated carbon A used has a BET specific surface area of 3000 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a film thickness of 0.23 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 1257 mg (88.5% yield) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 143 mg (yield 71.5%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 2)
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, activated carbon A (400 mg) was immersed in this sulfur cyclohexane solution and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon A. Subsequently, the activated carbon A was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon A.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and the activated carbon coated with sulfur was sedimented by centrifugation, and the solid content of the supernatant sulfur solution was measured and found to be 1.220 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 753 mg of sulfur coats 400 mg of activated carbon A. Therefore, the sulfur in the activated carbon coated with sulfur is 65.3 wt% (Table 1). Since the activated carbon A used has a BET specific surface area of 3000 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a film thickness of 0.31 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 1005 mg (yield 87.2%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 146 mg (yield 73.0%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 3)
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, activated carbon A (300 mg) was immersed in this sulfur cyclohexane solution and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon A. Subsequently, the activated carbon A was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon A.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and activated carbon coated with sulfur was settled by centrifugal separation. The solid content of the supernatant sulfur solution was measured and found to be 0.951 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 781 mg of sulfur coats 300 mg of activated carbon A. Therefore, the sulfur in the activated carbon coated with sulfur is 72.2 wt% (Table 1). Since the activated carbon A used has a BET specific surface area of 3000 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a film thickness of 0.43 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 951 mg (yield 88.0%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 145 mg (yield 72.5%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

Example 4
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, 200 mg of activated carbon A was immersed in this sulfur cyclohexane solution and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon A. Subsequently, the activated carbon A was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon A.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and activated carbon coated with sulfur was precipitated by centrifugal separation. The solid content of the supernatant sulfur solution was measured and found to be 1.196 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 758 mg of sulfur coats 200 mg of activated carbon A. Therefore, the sulfur in the activated carbon coated with sulfur is 79.1 wt% (Table 1). Since the activated carbon A used has a BET specific surface area of 3000 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a film thickness of 0.63 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 839 mg (yield 87.6%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 147 mg (yield 73.5%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 5)
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, 150 mg of activated carbon A was immersed in this cyclohexane solution of sulfur and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon A. Subsequently, the activated carbon A was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon A.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and the activated carbon coated with sulfur was sedimented by centrifugation, and the solid content of the supernatant sulfur solution was measured and found to be 1.283 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 740 mg of sulfur coats 150 mg of activated carbon A. Therefore, the sulfur in the activated carbon coated with sulfur is 83.1 wt% (Table 1). Since the activated carbon A used has a BET specific surface area of 3000 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a film thickness of 0.82 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 777 mg (yield 87.3%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 144 mg (yield 72.0%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Comparative Example 2)
In a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, a zirconia ball 40 g of 5 mmΦ, 99.8 mg of sulfur, and 20.2 mg of activated carbon A are made of zirconia with a capacity of 45 ml (for French, Premium line P-7). In a planetary ball mill (Premium line P-7, manufactured by Fritsch) for 1 hour at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation), followed by heat treatment at 25 ° C. for 1 hour, followed by synthesis By adding 80.0 mg of the solid electrolyte A prepared in Example 1 and further treating with a planetary ball mill at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation) for 2 hours, 146 mg (yield 73.0%) A positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 6)
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, 120 mg of activated carbon A was immersed in this cyclohexane solution of sulfur and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon A. Subsequently, the activated carbon A was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon A.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and the activated carbon coated with sulfur was sedimented by centrifugation, and the solid content of the supernatant sulfur solution was measured and found to be 1.142 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 769 mg of sulfur coats 120 mg of activated carbon A. Therefore, the sulfur in the activated carbon coated with sulfur is 86.5 wt% (Table 1). Since the activated carbon A used has a BET specific surface area of 3000 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a film thickness of 1.07 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 783 mg (yield 88.1%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 148 mg (yield 74.0%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Comparative Example 3)
In a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or lower, a zirconia ball 40 g of 5 mmΦ, 103.8 mg of sulfur, and 16.2 mg of activated carbon A are made of zirconia with a capacity of 45 ml (manufactured by Fritsch, for Premium line P-7). In a planetary ball mill (Premium line P-7, manufactured by Fritsch) for 1 hour at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation), followed by heat treatment at 25 ° C. for 1 hour, followed by synthesis By adding 80.0 mg of the solid electrolyte A prepared in Example 1 and further treating with a planetary ball mill at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation) for 2 hours, 143 mg (yield 71.5%) A positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 7)
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, activated carbon A (100 mg) was immersed in this sulfur cyclohexane solution and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon A. Subsequently, the activated carbon A was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon A.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and activated carbon coated with sulfur was settled by centrifugation, and the solid content of the supernatant sulfur solution was measured and found to be 1.200 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 757 mg of sulfur coats 100 mg of activated carbon A. Therefore, sulfur in the activated carbon coated with sulfur is 88.3 wt% (Table 1). Since the activated carbon A used has a BET specific surface area of 3000 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a thickness of 1.26 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 759 mg (yield 88.6%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 146 mg (yield 73.0%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Comparative Example 4)
In a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, a zirconia container having a capacity of 45 ml containing 40 g of 5 mmφ zirconia balls, 106.0 mg of sulfur, and 14.0 mg of activated carbon A (for Fritsch, Premium line P-7) In a planetary ball mill (Premium line P-7, manufactured by Fritsch) for 1 hour at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation), followed by heat treatment at 25 ° C. for 1 hour, followed by synthesis By adding 80.0 mg of the solid electrolyte A prepared in Example 1 and further processing with a planetary ball mill at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation) for 2 hours, 145 mg (yield 72.5%) A positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Comparative Example 5)
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, 50 mg of activated carbon A was immersed in this sulfur cyclohexane solution and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon A. Subsequently, the activated carbon A was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon A.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and the activated carbon coated with sulfur was settled by centrifugation, and the solid content of the supernatant sulfur solution was measured and found to be 1.166 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 764 mg of sulfur coats 50 mg of activated carbon A. Therefore, the sulfur in the activated carbon coated with sulfur is 93.9 wt% (Table 1). Since the activated carbon A used has a BET specific surface area of 3000 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a film thickness of 2.55 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 716 mg (yield 87.9%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 143 mg (yield 71.5%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 8)
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, 150 mg of activated carbon B was immersed in this sulfur cyclohexane solution and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon B. Subsequently, the activated carbon B was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon B.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and activated carbon coated with sulfur was settled by centrifugation, and the solid content of the supernatant sulfur solution was measured and found to be 1.051 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 788 mg of sulfur coats 150 mg of activated carbon B. Therefore, the sulfur in the activated carbon coated with sulfur is 84.0 wt% (Table 1). Since the activated carbon B used has a BET specific surface area of 2500 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a thickness of 1.05 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 822 mg (yield 87.7%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 144 mg (yield 72.0%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Comparative Example 6)
In a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, a zirconia container having a capacity of 45 ml containing 40 g of zirconia balls of 5 mmΦ, 100.8 mg of sulfur, and 19.2 mg of activated carbon B (made by Fritsch, Premium line P-7) In a planetary ball mill (Premium line P-7, manufactured by Fritsch) for 1 hour at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation), followed by heat treatment at 25 ° C. for 1 hour, followed by synthesis By adding 80.0 mg of the solid electrolyte A prepared in Example 1 and further treating with a planetary ball mill at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation) for 2 hours, 143 mg (yield 71.5%) A positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

Example 9
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, 150 mg of activated carbon C was immersed in this cyclohexane solution of sulfur and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse activated carbon C. Subsequently, the activated carbon C was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon C.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and the activated carbon coated with sulfur was sedimented by centrifugation, and the solid content of the supernatant sulfur solution was measured and found to be 1.108 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 776 mg of sulfur coats 150 mg of activated carbon C. Therefore, the sulfur in the activated carbon coated with sulfur is 83.8 wt% (Table 1). Since the activated carbon C used has a BET specific surface area of 1900 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a film thickness of 1.36 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 811 mg (yield: 87.6%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.0 mg of thin-film sulfur-coated activated carbon, and 80.0 mg of the solid electrolyte A prepared in Synthesis Example 1 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 148 mg (yield 74.0%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Comparative Example 7)
In a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, a zirconia container having a capacity of 45 ml containing 40 g of 5 mmφ zirconia balls, 100.6 mg of sulfur, and 19.4 mg of activated carbon C (made by Fritsch, for Premium line P-7) In a planetary ball mill (Premium line P-7, manufactured by Fritsch) for 1 hour at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation), followed by heat treatment at 25 ° C. for 1 hour, followed by synthesis By adding 80.0 mg of the solid electrolyte A prepared in Example 1 and further treating with a planetary ball mill at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation) for 2 hours, 146 mg (yield 73.0%) A positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Comparative Example 8)
1000 mg of sulfur and 20 g of cyclohexane were put into a 50 ml screw tube and stirred with a magnetic stirrer while heating to 60 ° C. to dissolve the sulfur. Next, 150 mg of activated carbon D was immersed in this sulfur cyclohexane solution and subjected to ultrasonic treatment (output 100 W, oscillation frequency 28 Hz, 40 minutes) to disperse the activated carbon D. Subsequently, the activated carbon D was coated with sulfur by stirring with a magnetic stirrer at 25 ° C. for 7 days to adsorb the sulfur to the activated carbon D.
About 2 g of the dispersion liquid after the sulfur coating was extracted, and activated carbon coated with sulfur was settled by centrifugation, and the solid content of the supernatant sulfur solution was measured and found to be 1.022 wt%. Since the concentration of the original sulfur solution is 4.762 wt%, 793 mg of sulfur coats 150 mg of activated carbon D. Therefore, the sulfur in the activated carbon coated with sulfur is 84.1 wt% (Table 1). Since the activated carbon D used has a BET specific surface area of 1500 m ² / g, sulfur having a specific gravity of 2 g / cm ³ has a film thickness of 1.76 nm.
By separating the activated carbon covered with sulfur from the sulfur solution by suction filtration of the remaining amount other than about 2 g extracted for calculating the coating amount and film thickness of sulfur, heat treatment at 160 ° C. for 1 hour, 831 mg (yield 88.1%) of thin film sulfur-coated activated carbon was obtained.
Next, in a glove box having an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 119.9 mg of thin-film sulfur-coated activated carbon, and 80.1 mg of the solid electrolyte A prepared in Synthesis Example 1 were made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 143 mg (yield 71.5%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Comparative Example 9)
In a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, a zirconia container having a capacity of 45 ml containing 40 g of zirconia balls of 5 mmΦ, 100.8 mg of sulfur, and 19.1 mg of activated carbon D (made by Fritsch, for Premium line P-7) In a planetary ball mill (Premium line P-7, manufactured by Fritsch) for 1 hour at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation), followed by heat treatment at 25 ° C. for 1 hour, followed by synthesis By adding 80.1 mg of the solid electrolyte A produced in Example 1 and further treating with a planetary ball mill at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation) for 2 hours, 142 mg (yield 71.0%) A positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 10)
A thin film sulfur-coated activated carbon was obtained in the same manner as in Example 2.
Next, in a glove box having an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.4 mg of thin-film sulfur-coated activated carbon, and 79.6 mg of the solid electrolyte B prepared in Synthesis Example 2 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 147 mg (yield 73.5%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 11)
A thin film sulfur-coated activated carbon was obtained in the same manner as in Example 3.
Next, in a glove box having an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.4 mg of thin-film sulfur-coated activated carbon, and 79.6 mg of the solid electrolyte B prepared in Synthesis Example 2 are made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 145 mg (yield 72.5%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 12)
A thin film sulfur-coated activated carbon was obtained in the same manner as in Example 4.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.3 mg of thin-film sulfur-coated activated carbon, and 79.7 mg of the solid electrolyte B produced in Synthesis Example 2 were made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 146 mg (yield 73.0%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 13)
A thin film sulfur-coated activated carbon was obtained in the same manner as in Example 5.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.3 mg of thin-film sulfur-coated activated carbon, and 79.7 mg of the solid electrolyte B produced in Synthesis Example 2 were made of zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 143 mg (yield 71.5%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Example 14)
A thin film sulfur-coated activated carbon was obtained in the same manner as in Example 7.
Next, in a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or less, 40 g of 5 mmφ zirconia balls, 120.2 mg of thin-film sulfur-coated activated carbon, and 79.8 mg of the solid electrolyte B prepared in Synthesis Example 2 were manufactured by zirconia having a capacity of 45 ml. Put in a container (French, Premium line P-7) and process for 2 hours with planetary ball mill (Fritch, Premium line P-7) at a rotation speed of 185 rpm and a rotation speed of 370 rpm (rotation and reverse rotation). As a result, 145 mg (yield 72.5%) of the positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Examples 15 to 19)
The positive electrode mixture was treated in the same manner as in Example 6 except that the heat treatment temperature of the activated carbon coated with sulfur separated from the sulfur solution was 25 ° C., 40 ° C., 60 ° C., 100 ° C., and 250 ° C., respectively. Obtained.
Using these positive electrode composites, a battery was produced according to the battery production method described above, and the discharge capacity was measured.

(Comparative Example 10)
In a glove box in an argon atmosphere with a dew point temperature of −70 ° C. or lower, a zirconia ball 40 g of 5 mmΦ, 103.8 mg of sulfur, and 16.2 mg of activated carbon A are made of zirconia with a capacity of 45 ml (manufactured by Fritsch, for Premium line P-7) In a planetary ball mill (Premium line P-7, manufactured by Fritsch) for 1 hour at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation), followed by heat treatment at 25 ° C. for 1 hour, followed by synthesis By adding 80.0 mg of the solid electrolyte A prepared in Example 1 and further treating with a planetary ball mill at a rotation speed of 185 rpm and a revolution speed of 370 rpm (rotation and reverse rotation) for 2 hours, 148 mg (yield 74.0%) A positive electrode mixture was obtained.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

(Comparative Example 11)
A positive electrode mixture was obtained in the same manner as in Comparative Example 10, except that the heat treatment temperature was 160 ° C.
Using this positive electrode mixture, a battery was prepared according to the battery preparation method described above, and the discharge capacity was measured.

In Comparative Examples 1 to 11 and Examples 1 to 19, the type of activated carbon and the BET specific surface area, the presence or absence of sulfur coating, the film thickness, the weight ratio of sulfur and activated carbon in activated carbon coated with sulfur (Comparative Examples 2 to 4, Tables 1 to 6 show the heat treatment temperature, the type of solid electrolyte, the composition of the positive electrode mixture, the discharge capacity per gram of sulfur, and the discharge capacity per gram of the positive electrode mixture layer.

From the above results, a thin film sulfur-coated activated carbon uniformly coated with sulfur having a predetermined film thickness can be easily obtained by the production method of the present invention. It has been clarified that the use of the positive electrode mixture can provide an all-solid-state lithium-sulfur battery having a large discharge capacity per positive electrode mixture layer and excellent rate characteristics.

DESCRIPTION OF SYMBOLS 1 Negative electrode collector 2 Negative electrode 3 Solid electrolyte layer 4 Positive electrode compound material layer 5 Positive electrode collector 10 All solid-state lithium-sulfur battery

Claims (7)

A step of immersing activated carbon having a BET specific surface area of 1800 m ² / g or more in a sulfur solution and coating the activated carbon with sulfur (a); and
An all-solid-state lithium-sulfur battery coated with sulfur having a film thickness of 0.2 to 1.4 nm, comprising the step (b) of separating the activated carbon coated with sulfur obtained in step (a) from the sulfur solution. A method for producing a thin film sulfur-coated activated carbon for a positive electrode mixture. A step (c) of heat-treating the activated carbon coated with sulfur separated in step (b);
The manufacturing method of the thin film sulfur covering activated carbon of Claim 1. The manufacturing method of the thin film sulfur covering activated carbon of Claim 2 whose temperature of heat processing is 60 degreeC or more in a process (c). The manufacturing method of the thin film sulfur covering activated carbon of Claim 3 whose temperature of heat processing is 100 degreeC or more in a process (c). The manufacturing method of the thin film sulfur covering activated carbon of any one of Claims 1-4 whose film thickness is 0.5-1.0 nm. A step of immersing activated carbon having a BET specific surface area of 1800 m ² / g or more in a sulfur solution and coating the activated carbon with sulfur (a),
Separating the sulfur-coated activated carbon obtained in step (a) from the sulfur solution; and
An all-solid-state lithium-sulfur battery comprising a step of mixing a thin film sulfur-coated activated carbon coated with sulfur having a film thickness of 0.2 to 1.4 nm obtained in step (b) and a solid electrolyte to obtain a positive electrode mixture A method for producing a positive electrode mixture to be used. A step of immersing activated carbon having a BET specific surface area of 1800 m ² / g or more in a sulfur solution and coating the activated carbon with sulfur (a),
Separating the activated carbon coated with sulfur obtained in step (a) from the sulfur solution (b);
Mixing the thin film sulfur-coated activated carbon coated with sulfur having a film thickness of 0.2 to 1.4 nm obtained in step (b) and a solid electrolyte to obtain a positive electrode mixture; and
A method for producing an all-solid-state lithium-sulfur battery comprising a positive electrode mixture layer, a solid electrolyte layer, a negative electrode, and a current collector, comprising a step of depositing the obtained positive electrode mixture on one side of a solid electrolyte layer.

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