JP7283657B2 - Sulfur positive electrode mixture and manufacturing method thereof, sulfur positive electrode, lithium sulfur solid state battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sulfur positive electrode mixture, a manufacturing method thereof, a sulfur positive electrode, and a lithium sulfur solid state battery.

2. Description of the Related Art In recent years, electronic devices, communication devices, and the like are rapidly becoming portable and cordless. As a power source for these electronic devices and communication devices, there is a demand for secondary batteries with high energy density and excellent load characteristics. expanding.
On the other hand, the popularization of electric vehicles and the promotion of the use of natural energy require batteries with even higher energy densities. Therefore, it is desired to develop a new lithium ion secondary battery to replace the lithium ion secondary battery in which a lithium composite oxide such as LiCoO ₂ is used as a constituent material of the positive electrode.

Sulfur has an extremely high theoretical capacity density of 1672 mAhg ^-1 , and a lithium-sulfur battery that uses sulfur as a positive electrode constituent material has the potential to achieve the highest theoretical energy density among batteries. ing. Therefore, research and development of lithium-sulfur batteries have been actively carried out.

Up to now, various researches have been made on positive electrode materials for lithium ion secondary batteries. Among positive electrode materials, sulfur has been attracting attention as a positive electrode material for many years due to its advantage of high capacity. Sulfur as a positive electrode active material functions as an electrode by repeating a reaction in which a disulfide bond is cleaved during discharge and a disulfide bond is regenerated during charge. From research on organic disulfide compounds, application to positive electrodes has been investigated. In recent years, elemental sulfur, which has a large number of disulfide bonds and thus has a large number of reactive electrons and is expected to have a high capacity, has attracted attention. Since sulfur has an eight-membered ring structure under normal temperature and pressure, if sulfur is represented as S8, the entire reaction formula in charging and discharging can be represented by the following formula (1).

Assuming that sulfur reacts to the final product Li ₂ S upon discharge, the capacity value of the positive electrode containing sulfur (sulfur positive electrode) is calculated to be 1675 mAhg ⁻¹ . The capacity value of the sulfur positive electrode is about 6 times the theoretical capacity value of LiCoO ₂ and corresponds to 10 times the actually observed capacity value of LiCoO ₂ . The capacity value of the sulfur positive electrode is the largest value as a positive electrode. The operating voltage of the sulfur positive electrode is about 50% to 60% of that of the conventional positive electrode made of LiCoO ₂ or the like, and the fact that the operating voltage is low is not preferable from the viewpoint of increasing the voltage. However, the sulfur positive electrode has an energy density of 2500 Whkg ^-1 and 2800 Whkg ^-1 , which is expressed as the product of battery voltage and capacity. This greatly increases its utility value.

Another advantage of sulfur is that it is an abundant resource.
On the other hand, the first problem with sulfur is that the utilization rate of sulfur as an active material is low. In a liquid-type lithium-sulfur battery that uses an electrolyte with lithium ion conductivity, sulfur is often in full contact with the electrolyte, so it is not difficult to secure a conduction path for lithium ions. . The electron conductivity of sulfur at room temperature (20° C.) is extremely low at 1×10 ⁻³⁰ Scm ⁻¹ . In addition, Li ₂ S generated by sulfur discharge also has an electronic conductivity of 1×10 ⁻¹³ Scm ⁻¹ or less. A technique of mixing a substance with sulfur with sulfur has been used.

However, even if it is combined with a substance having electron conductivity, it is difficult to ensure sufficient electron conduction paths for all sulfur. Furthermore, considering that it is necessary to add a conductive agent to sulfur, it is inevitable that the sulfur ratio in the electrode will decrease, and the capacity per unit mass and unit volume of the positive electrode will be even lower. Therefore, in order to increase the capacity of the positive electrode of a liquid-type lithium-sulfur battery, it is important to increase the utilization rate of sulfur while suppressing the amount of conductive additives other than sulfur.

A second problem with sulfur is the progress of the dissolution reaction. In a liquid-type lithium-sulfur battery, lithium polysulfide (LiS _n , n=2 to 8), which is a reaction intermediate during charging and discharging, is soluble in the electrolyte. In particular, lithium polysulfide (LiS _n ) has a high solubility when n=4-8. Therefore, since lithium polysulfide dissolves and flows out into the electrolyte, the amount of sulfur in the positive electrode decreases, resulting in a significant decrease in capacity during cycling.

A third problem related to sulfur is volume change during charging and discharging. Sulfur expands by 1.8 times in volume by becoming Li ₂ S through the discharge reaction represented by the above formula (1), and spreads the conductive aid around sulfur. Then, when the sulfur shrinks again due to the charging reaction, the contact between the sulfur and the conductive aid is lost, and the sulfur is isolated. Isolated sulfur can no longer accept electrons, so it no longer functions as an active material. As charge and discharge are repeated, the ratio of isolated sulfur increases and the capacity of the positive electrode decreases.

In order to construct a lithium-ion secondary battery with a sulfur positive electrode that does not contain lithium, it is necessary to use a lithium-containing material for the negative electrode. The reaction potential of sulfur is not so high as a positive electrode material. Therefore, in order to increase the voltage that can be obtained from a lithium ion secondary battery equipped with a sulfur positive electrode and to take advantage of the high capacity of the sulfur positive electrode, the negative electrode has the lowest oxidation-reduction potential and a theoretical capacity of 3861 mAhg ^-1 . And lithium in the very large metallic state is often used.

In order for the electrode of a lithium ion secondary battery to electrochemically function as an active material, both the ionic conductivity and the electronic conductivity in the electrode composite must be sufficient values. Therefore, in order to improve the electronic conductivity in the electrode composite, a method of mixing a substance having electronic conductivity such as carbon with sulfur has been used. In order to use sulfur, which has significantly lower electronic conductivity than conventional positive electrode materials such as _LiCoO2 , as an active material for electrodes, it is particularly important to select a conductive aid that is compatible with sulfur and a method for combining it. . As a method of compositing with a conductive aid, for example, a method of compositing with a carbon nanotube that is excellent in mechanical properties and electronic conductivity, and has characteristics such as thin thickness, high specific surface area, high flexibility, and high mechanical strength. Examples include a method of forming a composite with graphene, a method of forming a composite with porous carbon having pores, and the like. By selecting porous carbon as a conductive aid that combines with sulfur, the electron conduction path to sulfur is secured, and sulfur is isolated from the conductive aid due to volume changes due to elution of lithium polysulfide and charge-discharge reactions. can be suppressed. There are various methods for producing a sulfur-porous carbon composite.

Sugano et al., the present inventor, used a carbon replica having a three-dimensional honeycomb structure as a conductive aid, introduced sulfur into the pores by a vapor deposition method, and produced a solid electrolyte that is a lithium ion conductor. By mixing, we have attempted to produce an all-solid-state lithium-sulfur battery with high characteristics (see, for example, Non-Patent Document 1).

As described above, the liquid-type lithium-sulfur battery has the problem that the capacity decreases due to the elution of lithium polysulfide, which is a reaction intermediate during charging and discharging. On the other hand, an all-solid lithium-sulfur battery in which the electrolytic solution is replaced with a solid electrolyte not only does not cause any elution of lithium polysulfide, but also prevents adverse effects such as the shuttle effect accompanying the elution of lithium polysulfide. . On the other hand, however, all-solid-state lithium-sulfur batteries have new drawbacks due to the application of solid electrolytes. In a liquid-based lithium-sulfur battery, the electrolyte is a fluid, so contact between the sulfur and the electrolyte is always maintained. Therefore, the decrease in capacity due to isolation of sulfur due to expansion and contraction could be improved by reducing poor contact between sulfur and the conductive aid. However, in an all-solid-state lithium-sulfur battery, it is difficult to construct a good lithium-ion conduction path because the sulfur contacts the solid electrolyte at the solid-solid interface. Also, the electrolyte can always keep contact with sulfur due to its fluidity, but the solid electrolyte tends to lose contact due to expansion and contraction of sulfur. Therefore, when using a solid electrolyte, it is necessary to consider the method of synthesizing and compositing the positive electrode mixture more than when using an electrolytic solution.

All-solid-state lithium-sulfur batteries with three-dimensional mesoporous electro structures. Journal of Power Sources 330, 120-126, (2016).

As described above, in the all-solid-state lithium-sulfur battery, as the cycles are repeated, the contact area between the sulfur, the electronically conductive carbon and the lithium ion conductive solid electrolyte is reduced, and the capacity retention rate is reduced. There was a problem. .

The present invention has been made in view of the above circumstances. It is an object of the present invention to provide a material and a manufacturing method thereof, a sulfur positive electrode containing the sulfur positive electrode mixture, and a lithium-sulfur solid state battery including the sulfur positive electrode.

In order to solve the above problems, the present invention employs the following configuration.
[1] A carbon replica having a three-dimensional honeycomb structure and having pores with a pore diameter of 5 nm or more and 20 nm or less, and at least sulfur contained in the pores and a solid electrolyte, wherein the sulfur and the volume of the pores is 0.5 cm ³ /g or more and 2.5 cm ³ /g or less in a state where the solid electrolyte is included ,
A sulfur positive electrode mixture, wherein the solid electrolyte is Li ₆ PS ₅ Cl.

[2] The sulfur positive electrode mixture according to [1], which has a specific surface area of 100 m ² /g or more and 300 m ² /g or less .
[3] A current collector and a positive electrode mixture layer formed on the current collector, wherein the positive electrode mixture layer contains the sulfur positive electrode mixture according to [1] or [ 2 ] , sulfur positive electrode.
[ 4 ] A lithium-sulfur solid state battery comprising a sulfur positive electrode according to [ 3 ], a lithium negative electrode, and a solid electrolyte layer, wherein the solid electrolyte layer is disposed between the sulfur positive electrode and the lithium negative electrode .
[ 5 ] Sulfur is vapor-deposited on the surface and in the pores of a carbon replica having a three-dimensional honeycomb structure and pores with a pore diameter of 5 nm or more and 20 nm or less by a vapor deposition method. a step of preparing a carbon replica composite; a step of stirring and mixing an alcohol solution containing the sulfur-carbon replica composite and a solid electrolyte Li ₆ PS ₅ Cl to prepare a mixed solution; and depositing the solid electrolyte at least in the pores.

ADVANTAGE OF THE INVENTION According to the present invention, a sulfur positive electrode mixture, a method for producing the same, and a sulfur positive electrode mixture that can suppress a decrease in the contact area between sulfur and a solid electrolyte and a decrease in capacity retention rate as cycles are repeated. and a lithium-sulfur solid-state battery comprising the sulfur positive electrode.

1 is a cross-sectional view schematically showing an example of a main part of a sulfur positive electrode mixture according to one embodiment of the present invention; FIG. 1 is a cross-sectional view schematically showing an example of a main part of a sulfur positive electrode according to one embodiment of the present invention; FIG. 1 is a cross-sectional view schematically showing an example of a main part of a lithium-sulfur solid-state battery according to one embodiment of the present invention; FIG. FIG. 3 is a diagram showing capacity retention rates of battery cells of Examples and Comparative Examples. FIG. 4 shows the results of X-ray diffraction measurement of sulfur positive electrode mixtures of Examples and Comparative Examples. FIG. 4 is a diagram showing results of measurement of pore volumes of sulfur positive electrode mixtures of Examples and Comparative Examples.

<< Sulfur positive electrode mixture >>
A sulfur positive electrode mixture according to one embodiment of the present invention includes a carbon replica having a three-dimensional honeycomb structure and pores having a pore diameter of 5 nm or more and 20 nm or less, and at least Sulfur and a solid electrolyte are included, and the volume of the pores is 0.5 cm ³ /g or more and 2.5 cm ³ /g or less in a state in which the sulfur and the solid electrolyte are included.
The sulfur positive electrode mixture of the present embodiment has a three-dimensional honeycomb structure, a carbon replica having pores with a pore diameter of 5 nm or more and 20 nm or less, and sulfur and a solid electrolyte contained at least in the pores. And, the volume of the pores is 0.5 cm ³ /g or more and 2.5 cm ³ /g or less in a state where the sulfur and the solid electrolyte are included, so that the carbon replica that is a conductive aid can be used to increase the contact area between sulfur and the solid electrolyte, and to build electron and ion conduction paths between the sulfur and the solid electrolyte. As a result, it is possible to suppress a decrease in the contact area between sulfur and the solid electrolyte as the number of cycles increases, thereby suppressing a decrease in the capacity retention rate.

Hereinafter, the sulfur positive electrode mixture of this embodiment will be described in detail with reference to the drawings.
In the drawings used in the following description, in order to make it easier to understand the features of the present invention, there are cases where the main parts are enlarged for convenience, and the dimensional ratio of each component is the same as the actual one. not necessarily.

FIG. 1 is a cross-sectional view schematically showing an example of the essential part of the sulfur positive electrode mixture of this embodiment.
The sulfur positive electrode mixture 1 shown here includes a carbon replica 11 , sulfur 12 and a solid electrolyte 13 .
The carbon replica 11 has a three-dimensional honeycomb structure (closed cell structure). In the sulfur positive electrode mixture 1 , sulfur 12 and a solid electrolyte 13 are included in at least a plurality of cells (pores) 11 a forming a honeycomb structure of the carbon replica 11 . Note that the sulfur 12 and the solid electrolyte 13 may exist on the surface 11b of the carbon replica 11, as shown in FIG.

In the sulfur positive electrode mixture 1, the volume of the pores 11a of the carbon replica 11 is 0.5 cm ³ /g or more and 2.5 cm ³ /g or less in a state in which sulfur and a solid electrolyte are included.

A method for measuring the volume of the pores 11a of the carbon replica 11 is a nitrogen adsorption/desorption measurement method.

The sulfur positive electrode mixture 1 preferably has a specific surface area of 100 m ² /g or more and 300 m ² /g or less.

The specific surface area of the sulfur positive electrode mixture 1 is measured by the BET method based on nitrogen (N ₂ ) adsorption using a specific surface area meter.

The average particle size of the sulfur positive electrode mixture 1 is preferably 50 nm or more and 1000 nm or less. Here, the particle diameter of the sulfur positive electrode mixture 1 means the length of the maximum side of the particles observed with a scanning electron microscope.
If the average particle size exceeds the above upper limit, the composite will be insufficiently mixed, resulting in deterioration of battery performance.

A method for measuring the average particle size of the sulfur positive electrode mixture 1 is a method of observing the sulfur positive electrode mixture 1 with a scanning electron microscope.

The pore diameter (opening diameter of the pore 11a) of the carbon replica 11 is 5 nm or more and 20 nm or less, preferably 8 nm or more and 15 nm or less.
If the pore diameter of the carbon replica 11 exceeds the above upper limit, the output characteristics and cycle characteristics will deteriorate.

A method for measuring the pore diameter of the carbon replica 11 is a nitrogen adsorption/desorption measurement method.

Examples of the solid electrolyte 13 include aldirodite (Li ₆ PS ₅ Cl), aldirodite (Li ₆ PS ₅ Br), Li ₄ SnS ₄ and the like. Among these, aldirodite (Li ₆ PS ₅ Cl) is preferable from the viewpoint of ionic conductivity.

The solid electrolyte 13 exists as crystals inside the pores 11 a of the carbon replica 11 and on the surface 11 b of the carbon replica 11 .

<<Method for producing sulfur positive electrode mixture>>
A method for producing a sulfur positive electrode mixture according to an embodiment of the present invention is a carbon replica having a three-dimensional honeycomb structure and having pores with a pore diameter of 5 nm or more and 20 nm or less. A step of depositing sulfur by a vapor deposition method to prepare a sulfur-carbon replica composite (hereinafter referred to as a "first step"), and an alcohol solution containing the sulfur-carbon replica composite and a solid electrolyte. are stirred and mixed to prepare a mixed solution (hereinafter referred to as a "second step"), and the alcohol contained in the mixed solution is evaporated to deposit the solid electrolyte at least in the pores. and a step (hereinafter referred to as “third step”).
By having the above first step, the above second step, and the above third step, the method for producing a sulfur positive electrode mixture of the present embodiment contains sulfur and a solid electrolyte at least in the pores of the carbon replica. can be included. As a result, the contact area between the sulfur and the solid electrolyte is increased through the carbon replica, which is a conductive aid, in the pores of the carbon replica, and a conduction path for electrons and ions is constructed between the sulfur and the solid electrolyte. can do. This makes it possible to obtain a sulfur positive electrode mixture that can suppress a decrease in the contact area between sulfur and the solid electrolyte and a decrease in the capacity retention rate as the number of cycles increases.

"First step"
In the first step, a carbon replica having a three-dimensional honeycomb structure and pores with diameters of 5 nm or more and 20 nm or less is prepared.
As the carbon replica, the above may be synthesized, or a commercially available product may be used.

In the first step, sulfur is deposited on the surface and pores of the carbon replica by vapor deposition. A vapor deposition method will be described.
First, a carbon replica and powdered sulfur are put into a glass tube.
Next, the inside of the glass tube is evacuated to a vacuum state.
Next, the openings at the ends of the glass tube are welded, and the carbon replica and sulfur are sealed inside the glass tube.
Then, the carbon replica and sulfur in the glass tube are fired.
By the above method, sulfur is deposited on the surface and inside the pores of the carbon replica to obtain a sulfur-carbon replica composite.

Also, the obtained sulfur-carbon replica composite is subjected to a ball mill treatment. As a result, the aggregated sulfur-carbon replica composite is pulverized to improve the dispersibility in the alcohol solution in the second step.

"Second process"
In the second step, the sulfur-carbon replica composite obtained in the first step and an alcohol solution containing a solid electrolyte are mixed to prepare a mixed solution.

To prepare an alcohol solution containing a solid electrolyte, for example, the above solid electrolyte and alcohol are placed in a container together with a stirrer, and the solid electrolyte and alcohol are stirred and mixed with the stirrer.

Alcohols include, for example, ethanol and methanol.

To prepare the mixed solution, for example, the alcohol solution containing the sulfur-carbon replica composite and the solid electrolyte is placed in a container, and the sulfur-carbon replica composite and the alcohol solution are stirred and mixed.

"Third process"
In the third step, the alcohol contained in the mixed solution obtained in the second step is evaporated to deposit a solid electrolyte at least in the pores of the carbon replica.
The temperature for evaporating the alcohol is not particularly limited, and is appropriately adjusted according to the boiling point of the alcohol.
Moreover, the time for heating the alcohol is not particularly limited, and is appropriately adjusted according to the amount of alcohol contained in the mixed solution.

In the third step, the solid electrolyte may be deposited not only inside the pores of the carbon replica but also on the surface of the carbon replica.

Through the steps described above, the sulfur positive electrode mixture of the present embodiment is obtained.

<<Sulfur positive electrode>>
A sulfur positive electrode according to one embodiment of the present invention includes a current collector and a positive electrode mixture layer formed on the current collector, and the positive electrode mixture layer is the positive electrode mixture layer according to one embodiment of the present invention. Contains a sulfur positive electrode mixture.
Since the sulfur positive electrode of the present embodiment contains the sulfur positive electrode mixture of the present embodiment, it is possible to suppress the decrease in the contact area between sulfur and the solid electrolyte as the number of cycles increases, and the capacity retention rate decreases. can be suppressed.

Hereinafter, the structure of the sulfur positive electrode of this embodiment will be described in detail with reference to the drawings.
In the drawings used in the following description, in order to make it easier to understand the features of the present invention, there are cases where the main parts are enlarged for convenience, and the dimensional ratio of each component is the same as the actual one. not necessarily.

FIG. 2 is a cross-sectional view schematically showing an example of the main part of the sulfur positive electrode of this embodiment.
The sulfur positive electrode 20 shown here includes a current collector 21 and a positive electrode mixture layer 22 .
In the sulfur positive electrode 20 , the positive electrode mixture layer 22 is arranged on one surface (upper surface in FIG. 2 ) 21 a of the current collector 21 .

[Current collector]
In the sulfur positive electrode 20, the current collector 21 can function as a positive electrode current collector.
A conductive sheet is used as the current collector 21 .
Examples of the form of the conductive sheet include foil and mesh.

The constituent material of the conductive sheet may be conductive, but preferably has no reactivity with sulfur.
More specifically, examples of the constituent material of the conductive sheet include carbon, metals (single metals, alloys), and the like.
Among them, preferred constituent materials of the conductive sheet include constituent materials of the positive electrode current collector, more specifically, carbon, copper, aluminum, titanium, nickel, stainless steel, and the like.

The constituent materials of the conductive sheet may be of one type or two or more types, and when two or more types are used, their combination and ratio can be arbitrarily selected according to the purpose.

The thickness of the conductive sheet is not particularly limited, and may be appropriately set according to the purpose of the battery to be applied. Generally, the thickness of the conductive sheet is preferably 50 μm to 30000 μm, more preferably 100 μm to 3000 μm.

In addition, when the thickness of the conductive sheet clearly varies depending on the part of the conductive sheet, such as when the surface of the conductive sheet has a high degree of unevenness, the maximum thickness is taken as the thickness of the conductive sheet. (The thickness of the thickest part of the conductive sheet is defined as the thickness of the conductive sheet). This applies not only to the thickness of the conductive sheet, but also to the thickness of all layers (a sulfur positive electrode, a lithium negative electrode, a solid electrolyte and a lithium ion conductive layer, which will be described later).

[Positive electrode composite layer]
The positive electrode mixture layer 22 contains the sulfur positive electrode mixture of the present embodiment.

<<Lithium sulfur solid state battery>>
A lithium-sulfur solid-state battery according to an embodiment of the present invention includes a sulfur positive electrode according to an embodiment of the present invention, a lithium negative electrode, and a solid electrolyte layer, wherein the solid electrolyte layer comprises the sulfur positive electrode and the lithium It is arranged between the negative electrode.
Since the lithium-sulfur solid-state battery of the present embodiment includes the sulfur positive electrode of the present embodiment, the contact area between sulfur and the solid electrolyte is prevented from decreasing as the number of cycles increases, and the capacity retention rate decreases. can be suppressed.

Hereinafter, the structure of the lithium-sulfur solid state battery of the present embodiment will be described in detail with reference to the drawings.
In the drawings used in the following description, in order to make it easier to understand the features of the present invention, there are cases where the main parts are enlarged for convenience, and the dimensional ratio of each component is the same as the actual one. not necessarily.

FIG. 1 is a cross-sectional view schematically showing an example of the essential part of the lithium-sulfur solid-state battery of this embodiment.
A lithium-sulfur solid-state battery 100 shown here includes a sulfur positive electrode 110 , a lithium negative electrode 120 , and a solid electrolyte layer 130 .
In lithium-sulfur solid-state battery 100 , solid electrolyte layer 130 is disposed between sulfur positive electrode 110 and lithium negative electrode 120 . That is, in lithium-sulfur solid-state battery 100, sulfur positive electrode 110, solid electrolyte layer 130, and lithium negative electrode 120 are stacked in this order in the thickness direction.

In the lithium-sulfur solid-state battery 100, for example, the sulfur positive electrode 110 and the lithium negative electrode 120 are further provided with terminals for connection to external circuits.
Further, in the lithium-sulfur solid-state battery 100, the entire laminated structure of the above-described sulfur positive electrode 110, solid electrolyte layer 130 and lithium negative electrode 120 is housed in a container, if necessary.
In addition, the lithium-sulfur solid-state battery 100 further includes a mechanism (leakage suppression mechanism) that suppresses the molten sulfur in the sulfur positive electrode 110 from leaking to the outside of the lithium-sulfur solid-state battery 100, if necessary. may For example, the container may also serve as such a leakage suppression mechanism.
Next, the configuration of each layer of the lithium-sulfur solid-state battery of this embodiment will be described in detail.

<Sulfur positive electrode>
The sulfur cathode 110 is composed of the sulfur cathode 20 described above.

<Lithium negative electrode>
The lithium negative electrode 120 in the lithium-sulfur solid-state battery 100 of this embodiment may be a known one.

The thickness of the lithium negative electrode 120 is not particularly limited, and may be appropriately set according to the purpose of the battery to which it is applied. Generally, the thickness of the lithium negative electrode 120 is preferably 10 μm to 2000 μm, more preferably 100 μm to 1000 μm.

<Solid electrolyte>
The constituent material of the solid electrolyte layer 130 in the lithium-sulfur solid-state battery 100 of the present embodiment is not particularly limited, and may be any of a crystalline material, an amorphous material, and a glass material.
More specifically, the constituent material of the solid electrolyte layer 130 includes, for example, a material containing no sulfide and containing an oxide (in this specification, may be referred to as an “oxide-based material”), at least sulfide known materials, such as materials containing substances (which may be referred to herein as "sulfide-based materials").

_Examples of _the oxide- _{based material} include _Li7La3Zr2O12 ( _{LLZ )} , _{Li2.9PO3.3N0.46} ( _LIPON ), _{La0.51Li0.34TiO2.94 , Li1.3Al0.3Ti1.7 ( PO4 ) 3 , 50Li4SiO4.50Li3BO3 , Li3.6Si0.6P0.4O4 , Li1.07Al0 _ _ _ .69} Ti _1.46 (PO ₄ ) ₃ , Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ and the like.
Examples of the oxide-based material include those obtained by adding (doping) elements such as aluminum, tantalum, niobium, and bismuth to composite oxides such as Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ). be done. Here, the elements to be added may be of one type or two or more types, and when two or more types are added, their combination and ratio can be arbitrarily selected according to the purpose.

Examples _{of the} sulfide _{- based material} include _Li10GeP2S12 (LGPS) _{, Li3.25Ge0.25P0.75S4} , _{30Li2S.26B2S3.44LiI} , _{and 63Li2S} . _{36SiS2.1Li3PO4 , 57Li2S.38SiS2.5Li4SiO4 , 70Li2S.30P2S5 ( LISPS ) , 50Li2S.50GeS2 , Li7P3S11 , Li3 . _ 25} P _0.95 S ₄ and the like.

The constituent materials of the solid electrolyte layer 130 may be of one type or two or more types, and when two or more types are used, the combination and ratio thereof can be arbitrarily selected according to the purpose.

The constituent material of the solid electrolyte layer 130 is preferably the above-described oxide-based material because it has high stability in the air and can produce a highly dense solid electrolyte.

The thickness of the solid electrolyte layer 130 is not particularly limited, and may be appropriately set according to the purpose of the battery to which it is applied. Generally, it is preferable that the thickness of the solid electrolyte layer 130 is 10 μm to 1200 μm. When the thickness of the solid electrolyte layer 130 is equal to or greater than the lower limit, the manufacturing and handling properties thereof are further improved. Since the thickness of the solid electrolyte layer 130 is equal to or less than the upper limit, the resistance value of the lithium-sulfur solid-state battery 100 is further reduced.

The solid electrolyte layer 130 can be manufactured, for example, by selecting raw materials such as metal oxides, metal hydroxides, and metal sulfides according to the intended type and firing the raw materials. The amount of raw material to be used may be appropriately set in consideration of the atomic number ratio of each metal in the solid electrolyte layer 130 .

The lithium-sulfur solid-state battery 100 of the present embodiment is not limited to the above-described ones, and part of the configuration has been changed, deleted, or added to the ones described so far without departing from the spirit of the present invention. can be anything.

<Other layers>
For example, the lithium-sulfur solid-state battery 100 of the present embodiment includes one or more other layers that do not correspond to any of the sulfur positive electrode 110, the solid electrolyte layer 130, and the lithium negative electrode 120, one layer for each type. Alternatively, it may have two or more layers.
The other layer is not particularly limited as long as it does not impair the effects of the present invention, and can be arbitrarily selected according to the purpose.
Examples of the other layer include a gold sputtered layer and a lithium ion conductive layer, which will be described later.

[Sputtered gold layer]
The lithium-sulfur solid-state battery 100 of this embodiment may comprise a gold sputtered layer interposed between the solid electrolyte layer 130 and the lithium anode 120 .
For example, in the lithium-sulfur solid-state battery 100 in which a gold sputtered layer is arranged between the lithium negative electrode 120 and the solid electrolyte layer 130, and these three layers are in direct contact with each other in this order, the gold sputtered layer is The interfacial resistance value at the lithium anode interface is reduced compared to when it is not arranged.

The thickness of the sputtered gold layer is preferably 50 nm or more, more preferably 100 nm to 200 nm.

[Lithium ion conductive layer]
The lithium-sulfur solid-state battery 100 of this embodiment may include a lithium-ion conductive layer disposed between the solid electrolyte layer 130 and the lithium negative electrode 120 .
The lithium ion conductive layer is a layer that contains an ionic liquid and conducts lithium ions between the lithium negative electrode 120 and the solid electrolyte layer 130 .

More specifically, the lithium ion conductive layer has one surface (in this specification, sometimes referred to as the “first surface”) to the other surface (in this specification, the “second surface”). (sometimes referred to as )). Therefore, liquid substances and fine substances can move between the lithium negative electrode 120 and the solid electrolyte layer 130 via the lithium ion conductive layer.
Furthermore, the lithium ion conductive layer retains the ionic liquid in the voids and the like. Lithium ions can be dissolved in this ionic liquid. Therefore, lithium ions can be easily conducted between the lithium negative electrode 120 and the solid electrolyte layer 130 (thickness direction in the lithium ion conductive layer) through the lithium ion conductive layer.

In the present specification, the portion of the lithium ion conductive layer that has the voids, holds the ionic liquid, and maintains the shape of the lithium ion conductive layer is referred to as a "main body portion". That is, the lithium ion conductive layer includes the body portion and the ionic liquid retained by the body portion.

In the lithium-sulfur solid-state battery 100 of the present embodiment, due to the presence of the lithium ion conductive layer, the ionic liquid in the lithium ion conductive layer causes the lithium ion conductive layer, in other words, between the lithium negative electrode and the solid electrolyte. , the deposition of metallic lithium is suppressed.
Here, "the deposition of metallic lithium is suppressed in the lithium ion conductive layer" means "no metallic lithium is deposited in the lithium ion conductive layer, or even if metallic lithium is deposited in the lithium ion conductive layer, also means that the amount of precipitation is very small." Therefore, the lithium ion conductive layer smoothly conducts lithium ions between the lithium negative electrode 120 and the solid electrolyte layer 130 . Furthermore, by suppressing the deposition of metallic lithium in this way, the deposition of metallic lithium is also suppressed in the solid electrolyte layer 130 . That is, in the lithium-sulfur solid-state battery 100, the continuous deposition of metallic lithium from the lithium-ion conductive layer through the solid electrolyte layer 130 to the sulfur positive electrode 110 is suppressed. As a result, in the lithium-sulfur solid-state battery 100, for example, short circuits and cracks in the solid electrolyte layer 130 can be suppressed during charging and discharging.

(main body)
The main body of the lithium ion conductive layer may be, for example, a porous body or a fibrous material in which a fibrous material is aggregated to form a layer (referred to as a "fiber aggregate" in this specification). sometimes), etc.

The main body preferably does not react with the lithium negative electrode 120 under the temperature conditions during operation of the lithium-sulfur solid-state battery 100, does not dissolve, and does not deteriorate. Here, "alteration of the main body" means that the composition of the components of the main body changes. The operating temperature of the lithium-sulfur solid-state battery 100 is, for example, 110° C. to 160° C., as described above. Therefore, the body of the lithium ion conductive layer is preferably stable under such temperature conditions.

Examples of the constituent material of the porous body or fiber assembly of the main body include synthetic resin, glass, and paper, and synthetic resin or glass is preferable.
Among others, it is more preferable that the constituent material of the main body is polyimide or glass. That is, the lithium ion conductive layer more preferably contains polyimide or glass as its constituent material.

The constituent material of the body portion of the lithium ion conductive layer may be of one type or two or more types, and when two or more types are used, the combination and ratio thereof can be arbitrarily selected according to the purpose.

(ionic liquid)
Examples of the ionic liquid contained in the lithium ion conductive layer include those similar to the ionic liquid contained in the above-described sulfur positive electrode 110 (for example, an ionic compound that is liquid at a temperature of less than 170° C., a solvated ionic liquid, etc.). .

The ionic liquid contained in the lithium ion conductive layer may be of one type or two or more types, and when two or more types are used, the combination and ratio thereof can be arbitrarily selected according to the purpose.

The ionic liquid contained in the lithium ion conductive layer may be the same as or different from the ionic liquid contained in the sulfur positive electrode described above.

The ionic liquid contained in the lithium ion conductive layer is preferably a solvated ionic liquid comprising a glyme-lithium salt complex. By containing such an ionic liquid in the lithium ion conductive layer, the effect of suppressing deposition of metallic lithium in the solid electrolyte layer 130 is enhanced.

The content of the ionic liquid in the lithium ion conductive layer is not particularly limited.
However, the ratio of the total volume of the ionic liquid retained in the lithium ion conductive layer to the total volume of the voids in the main body of the lithium ion conductive layer ([Total ionic liquid retained in the lithium ion conductive layer Volume]/[total volume of voids in main body of lithium ion conductive layer]×100) is preferably 80 to 120% by volume at room temperature.
When the ratio is equal to or higher than the lower limit, the effect of suppressing precipitation of metallic lithium in solid electrolyte layer 130 is further enhanced. Excessive use of the ionic liquid is suppressed because the ratio is equal to or less than the upper limit.
The reason why the ratio can be greater than 100% by volume is that the ionic liquid can exist in the lithium ion conductive layer in addition to the voids of the main body.
In this specification, the term "ordinary temperature" means a temperature at which no particular cooling or heating is applied, that is, a normal temperature.

The lithium ion conductive layer may consist of one layer (single layer), or may consist of multiple layers of two or more layers. When the lithium ion conductive layer consists of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited.
In this specification, not only in the case of the lithium ion conductive layer, the phrase "multiple layers may be the same or different" means "all layers may be the same or all layers may be the same. may be different, or only some of the layers may be the same", and further, "the plurality of layers are different from each other" means that "at least one of the constituent material and thickness of each layer is different from each other. means 'different'.

The thickness of the lithium ion conductive layer is not particularly limited.
The thickness of the lithium ion conductive layer consisting of multiple layers means the total thickness of all layers constituting the lithium ion conductive layer.

However, the thickness of the lithium ion conductive layer is preferably 10 μm or more in order to further enhance the effect of suppressing deposition of metallic lithium in the solid electrolyte layer 130 . When the thickness of the lithium ion conductive layer is equal to or greater than the lower limit value, metallic lithium is not deposited in the lithium ion conductive layer, or even if a trace amount of metallic lithium is deposited in the lithium ion conductive layer, The influence does not extend into the solid electrolyte layer 130 . As a result, in the lithium-sulfur solid-state battery 100, continuous deposition of metallic lithium from the lithium-ion conductive layer through the solid electrolyte layer 130 to the sulfur positive electrode 110 is suppressed.

On the other hand, the thickness of the lithium ion conductive layer is preferably 100 μm or less so that the thickness of the lithium ion conductive layer does not become excessive (more appropriate).
Generally, the thinner the lithium ion conductive layer, the lower the resistance value in the lithium ion conductive layer and the higher the energy density of the lithium-sulfur solid-state battery 100 .

The lithium-sulfur solid-state battery 100 of this embodiment has excellent battery characteristics as described above, and is highly safe. Taking advantage of these features, the lithium-sulfur solid-state battery 100 is suitable for use as, for example, household power sources; emergency power sources; power sources for airplanes, electric vehicles, and the like.

<<Method for producing lithium-sulfur solid-state battery>>
The lithium-sulfur solid-state battery of the present embodiment can be manufactured, for example, by a manufacturing method including a step of laminating the sulfur positive electrode, the solid electrolyte and the lithium negative electrode in this order in the thickness direction.
For example, the lithium-sulfur solid-state battery of the present embodiment can be manufactured in the same manner as known lithium-sulfur solid-state batteries, except that the specific steps described above are performed as the step of manufacturing the sulfur positive electrode.

<Step of Producing Another Layer>
In the case of producing a lithium-sulfur solid-state battery comprising the other layer of the present embodiment, in the above-described production method, the other layer may be produced with a timing and method suitable for the type. .

[Step of producing gold sputter layer]
The sputtered gold layer can be produced by sputtering gold onto a target portion (usually, the surface of the solid electrolyte layer 130 on the lithium negative electrode 120 side) by a known method.

[Step of Producing Lithium Ion Conductive Layer]
For the lithium ion conductive layer, for example, a first raw material composition containing a constituent material of the main body, an ionic liquid, and optionally a solvent is prepared, and the lithium ion conductive layer is formed on the surface to be formed with the above It can be formed by coating the first raw material composition and drying it if necessary. This method is a method of forming the main body and the lithium ion conductive layer at the same time. When no solvent is used, drying of the coated first raw material composition is unnecessary.

In the preparation of the first raw material composition, the temperature and time for adding and mixing each raw material are not particularly limited as long as each raw material does not deteriorate.
For example, the temperature during mixing may be 15° C. to 50° C., but this is an example.
The method of mixing each raw material is not particularly limited, and a method of mixing by rotating a stirring rod, a stirrer, or a stirring blade; a method of mixing using a mixer; a method of mixing by applying ultrasonic waves, etc. It may be appropriately selected from the methods.

The first raw material composition can be applied to the formation target surface of the lithium ion conductive layer by a known method.
The temperature of the first raw material composition to be applied is not particularly limited as long as the surface to be formed of the lithium ion conductive layer, the constituent material of the main body, the ionic liquid, the solvent, and the like are not deteriorated. For example, the temperature of the first raw material composition at this time may be 15° C. to 50° C., but this is an example.

When drying the first raw material composition, the drying can be performed under normal pressure or reduced pressure by a known method. The drying temperature of the first raw material composition is not particularly limited, and may be, for example, 20° C. to 100° C., but this is an example.

When the surface to be formed of the lithium ion conductive layer is the surface on which the lithium ion conductive layer is arranged in the lithium sulfur solid state battery (for example, the surface of the lithium negative electrode side of the solid electrolyte, the surface of the solid electrolyte side of the lithium negative electrode, etc.) , the formed lithium ion conductive layer does not need to be moved to another location, and can be left as it is.
On the other hand, when the target surface for forming the lithium ion conductive layer is not the surface on which the lithium ion conductive layer is arranged in the lithium sulfur solid state battery, the formed lithium ion conductive layer is peeled off from this surface, and the lithium sulfur solid state battery It can be moved by sticking it to the desired placement surface inside.

Further, the lithium ion conductive layer is formed, for example, by impregnating the main body with an ionic liquid, or by preparing a mixed liquid containing an ionic liquid and a solvent, and impregnating the main body with the mixed liquid. It can also be formed by drying the impregnated main body if necessary. This method is a method using a pre-formed main body. When no solvent is used, drying of the main body after impregnation is unnecessary.
In this case, the main body is not placed on the surface of the lithium-sulfur solid-state battery on which the lithium-ion conductive layer is arranged, but is handled independently, and after forming the lithium-ion conductive layer, the lithium ions obtained Preferably, the conductive layer is further laminated to the intended placement surface in the lithium-sulphur solid state battery.

The main body can be produced by a known method, for example, by preparing a second raw material composition containing constituent materials of the main body and molding the second raw material composition.
Also, the body portion may be a commercially available product.

Examples of the method for impregnating the main body with the ionic liquid or the mixed liquid include a method of coating the main body with the ionic liquid or the mixed liquid, and a method of immersing the main body in the ionic liquid or the mixed liquid. methods and the like.

The ionic liquid or mixed solution can be applied to the main body by a known method.
The temperature of the ionic liquid or mixed liquid with which the main body is impregnated is not particularly limited as long as the raw materials such as the main body, the ionic liquid and the solvent do not deteriorate. For example, the temperature of the ionic liquid or mixed liquid during impregnation may be 15° C. to 50° C., but this is an example.

Drying of the main body after being impregnated with the mixed liquid can be performed under normal pressure or reduced pressure by a known method. The drying temperature at this time is not particularly limited, and may be, for example, 20° C. to 100° C., but this is just an example.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples.

[Example]
"Manufacturing of Sulfur Cathode Mixture"
A carbon replica having a three-dimensional honeycomb structure and pores with a pore diameter of 10 nm was prepared.
A carbon replica and powdered sulfur (purity: 99.99%, crystallite size: 75 μm, manufactured by Kojundo Chemical Laboratory Co., Ltd.) were put into a glass tube with an inner diameter of 10 mm. The mixing ratio of carbon replica and sulfur was 70% by mass:30% by mass.
Next, the inside of the glass tube was evacuated to a vacuum state.
Next, the opening at the end of the glass tube was welded, and a carbon replica and sulfur were sealed inside the glass tube.
The carbon replica and sulfur in the glass tube were then fired. Firing conditions were as follows. After raising the temperature from room temperature to 200° C. over 1 hour, it was held at 200° C. for 2 hours, and then cooled from 200° C. to room temperature by natural cooling.
By the above method, sulfur was deposited on the surface and inside the pores of the carbon replica to obtain a sulfur-carbon replica composite.
The resulting sulfur-carbon replica composite was ball milled for 10 minutes.
Next, an alcohol solution containing a sulfur-carbon replica composite and an aldirodite (Li ₆ PS ₅ Cl) as a solid electrolyte was stirred and mixed to prepare a mixed solution. At this time, the mixing ratio of the carbon replica, sulfur and aldirodite was 21% by mass:9% by mass:70% by mass.
As the alcohol, ethanol (super-dehydrated, purity: 99.5%, manufactured by Wako Pure Chemical Industries, Ltd.) was used.
The content of aldirodite in the alcohol solution was set to 10% by mass.
The sulfur-carbon replica composite and the alcohol solution were mixed so that the total content of the sulfur-carbon replica composite and aldirodite in the mixed solution was 10% by mass.
Next, the mixed solution was heated at 150° C. for 1 hour to evaporate the ethanol contained in the mixed solution, deposit a solid electrolyte on the surface and in the pores of the carbon replica, and prepare the sulfur positive electrode mixture of the example. Obtained.

"Manufacturing of Sulfur Cathode"
A slurry containing a sulfur positive electrode mixture and a binder is applied to one surface of a carbon cloth (mass 7 mg, diameter 10 mm, thickness 1000 μm) to form a coating film, and the coating film is heated together with the carbon cloth. Then, a positive electrode mixture layer containing the sulfur positive electrode mixture was formed on one surface of the carbon cloth to obtain the sulfur positive electrode of the example.

"Manufacturing Lithium Sulfur Solid State Battery"
(Production of solid electrolyte)
Lanthanum hydroxide (purity 99.99%, Kojundo Chemical Laboratory Co., Ltd.) (40.38 g), lithium hydroxide (purity 98.0%, Kanto Chemical Co., Ltd.) (20.44 g) and zirconium oxide (Tosoh Corporation ) (17.47 g) were weighed and mixed while pulverizing in a ball mill for 2 hours. The obtained powder (73.10 g) was weighed, transferred to a ceramic container for firing, fired at 900 ° C. for 15 hours using an electric furnace, cooled at a temperature decrease rate of 5 ° C./min, and finally cooled to room temperature. to obtain a lithium-lanthanum-zirconium composite oxide.
The resulting composite oxide (54.67 g) and aluminum oxide (γ-alumina, purity 99.99%, manufactured by Kojundo Chemical Laboratory Co., Ltd.) (0.90 g) were weighed and ground in a ball mill for 2 hours. while mixing. A disk-shaped pellet having a diameter of 18 mm and a thickness of 1.5 mm was produced by molding the obtained mixture using a double-axis press.
Transfer the pellets (0.5 g) obtained above to a ceramic container for firing spread with mother powder (mixed powder of lanthanum hydroxide, lithium hydroxide, zirconium oxide and aluminum oxide), and cover the pellets with mother powder. , was fired using an electric furnace. Firing conditions were as follows. That is, the temperature was raised from room temperature to 1,200° C. at a temperature elevation rate of 5° C./min, maintained at 1,200° C. for 24 hours, cooled at a temperature drop rate of 5° C./min, and finally cooled to room temperature. Next, the mother powder adhering to the pellet was removed by polishing.
As described above, a pellet-shaped aluminum-doped lithium-lanthanum-zirconium composite oxide (Al-doped LLZ) compact (Li _6.25 Al _0.25 La ₃ Zr ₂ O ₁₂ , diameter 15 mm, thickness of 1.0 mm) was obtained.

(Formation of gold sputter layer)
A circular polyimide tape (thickness: 0.09 mm, diameter: 18 mm) was hollowed out concentrically with a diameter of 10 mm to form a ring-shaped masking tape.
Next, this masking tape was attached to the negative electrode side surface of the Al-doped LLZ compact obtained above.
Next, gold was sputtered onto the exposed surface to serve as the negative electrode (the region not masked with the masking tape of the surface to serve as the negative electrode), thereby forming a sputtered layer of gold. After forming the gold sputter layer, the masking tape was removed from the Al-doped LLZ compact.

(Manufacturing of Lithium Sulfur Solid State Battery)
Using a stainless steel battery cell container for electrochemical tests, the sulfur positive electrode obtained above is placed in this container, and the Al-doped LLZ molded body is placed on the sulfur positive electrode so that the positive electrode side surface is was placed facing the sulfur positive electrode side.
Next, a lithium foil (10 mm in diameter, 600 μm in thickness) as a negative electrode was placed on the sputtered gold layer provided on the Al-doped LLZ molded body and brought into close contact therewith.
Next, a stainless steel foil (diameter 15 mm, thickness 500 μm) was placed on the negative electrode as a negative electrode current collector.
Next, a stainless steel washer was placed on the negative electrode current collector, and finally the top lid was closed.
As a result, a battery cell (lithium-sulfur solid state battery) of Example having a structure in which the negative electrode, the sputtered gold layer, the solid electrolyte, and the sulfur positive electrode were laminated in this order was obtained.

[Comparative example]
"Manufacturing of Sulfur Cathode Mixture"
A sulfur-carbon replica composite was obtained in the same manner as in Examples.
The resulting sulfur-carbon replica composite was ball milled for 10 minutes.
Next, algyrodite (Li ₆ PS ₅ Cl) was added to the sulfur-carbon replica composite, and they were subjected to ball milling for 10 minutes to obtain a sulfur positive electrode mixture of a comparative example.
At this time, the mixing ratio of the carbon replica, sulfur and aldirodite was 21% by mass:9% by mass:70% by mass.

"Manufacturing of Sulfur Cathode"
A sulfur positive electrode of Comparative Example was obtained in the same manner as in Example except that the sulfur positive electrode mixture of Comparative Example was used.

"Manufacturing Lithium Sulfur Solid State Battery"
A battery cell (lithium sulfur solid state battery) of Comparative Example was obtained in the same manner as in Example except that the sulfur positive electrode of Comparative Example was used.

[evaluation]
<Evaluation of battery characteristics>
The capacity retention ratios of the battery cells obtained in Examples and Comparative Examples were evaluated.
At an environmental temperature of 25 ° C., constant current discharge is performed at a current value of 0.0376 mA until the voltage of the sulfur positive electrode reaches 0.4 V with respect to the Li-In equilibrium voltage, and after reaching 0.4 V, 60 minutes. Constant voltage charging was performed. After resting, the battery was charged at a constant current of 0.0376 mA at an environmental temperature of 25° C. until the voltage of the sulfur positive electrode reached 2.4 V with respect to the equilibrium voltage of Li—In. This test was repeated for 30 cycles, and the discharge capacity at each cycle relative to the discharge capacity at the second cycle was taken as the capacity retention rate. The results are shown in FIG.
From FIG. 4, it was confirmed that the battery cell of this example had better battery characteristics than the battery cell of the comparative example.

<Composition analysis of sulfur positive electrode mixture>
A composition analysis was performed on the sulfur positive electrode mixtures obtained in Examples and Comparative Examples.
A small amount of the sulfur positive electrode mixture obtained in Examples and Comparative Examples was sampled and vacuum-dried at 150 ° C. for 1 hour. Analysis was performed using an X-ray diffractometer (manufactured by Rigaku Corporation). The results are shown in FIG. As Reference Example 1, FIG. 5 also shows an X-ray diffraction pattern of aldirodite (Li ₆ PS ₅ Cl).
From FIG. 5, since the sulfur positive electrode mixture of this example exhibits an X-ray diffraction pattern similar to that of aldirodite (Li ₆ PS ₅ Cl), aldirodite (Li ₆ PS) is present in the pores of the carbon replica. ₅ Cl).

<Measurement of pore volume of sulfur positive electrode mixture>
Pore volumes of the sulfur positive electrode mixtures obtained in Examples and Comparative Examples were measured.
The pore volumes of the sulfur positive electrode mixtures obtained in Examples and Comparative Examples were measured by the BET method using a specific surface area meter (trade name: BELSORP-mini, manufactured by Microtrack Bell Co., Ltd.). The results are shown in FIG. FIG. 6 shows, as Reference Example 2, the pore volume distribution of only the carbon replica, and as Reference Example 3, the pore volume distribution of the sulfur-carbon replica composite.
From FIG. 6, the sulfur positive electrode mixture of this example has a reduced pore volume peak, so it is considered that aldirodite (Li ₆ PS ₅ Cl) is included in the pores of the carbon replica. .

INDUSTRIAL APPLICABILITY The present invention can be used in the general field of lithium-sulfur solid state batteries.

Reference Signs List 1 Sulfur positive electrode mixture, 11 Carbon replica, 12 Sulfur, 13 Solid electrolyte, 20 Sulfur positive electrode, 21 Current collector, 22 Positive electrode mixture Material layer 100 Lithium sulfur solid battery 110 Sulfur positive electrode 120 Lithium negative electrode 130 Solid electrolyte layer

Claims (5)

A carbon replica having a three-dimensional honeycomb structure and having pores with a pore diameter of 5 nm or more and 20 nm or less, and sulfur and a solid electrolyte contained in at least the pores,
The pore volume is 0.5 cm ³ /g or more and 2.5 cm ³ /g or less in a state in which the sulfur and the solid electrolyte are included ,
A sulfur positive electrode mixture, wherein the solid electrolyte is Li ₆ PS ₅ Cl. The sulfur positive electrode mixture according to claim 1, having a specific surface area of 100 m ² /g or more and 300 m ² /g or less. A current collector and a positive electrode mixture layer formed on the current collector,
A sulfur positive electrode, wherein the positive electrode mixture layer contains the sulfur positive electrode mixture according to claim 1 or 2 . A sulfur positive electrode according to claim 3 , a lithium negative electrode, and a solid electrolyte layer,
A lithium-sulfur solid-state battery, wherein the solid electrolyte layer is disposed between the sulfur positive electrode and the lithium negative electrode. Sulfur is deposited on the surface and in the pores of a carbon replica having a three-dimensional honeycomb structure and pores with a pore diameter of 5 nm or more and 20 nm or less by a vapor deposition method to form a sulfur-carbon replica composite. creating a body;
a step of stirring and mixing an alcohol solution containing the sulfur-carbon replica composite and a solid electrolyte Li ₆ PS ₅ Cl to prepare a mixed solution;
evaporating the alcohol contained in the mixed solution to deposit the solid electrolyte at least in the pores.

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