JP7113424B2 - Lithium-sulfur solid state battery, positive electrode sheet for battery, negative electrode sheet for battery, laminated battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lithium-sulfur solid-state battery, a positive electrode sheet for batteries, a negative electrode sheet for batteries , and a laminated 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, secondary batteries with high energy density and excellent load characteristics are in demand, and the use of lithium secondary batteries with high voltage, high energy density and excellent cycle characteristics is expanding. is doing.
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 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 mAh / g, 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.

When an organic electrolyte is used as the electrolyte for a lithium-sulfur battery, sulfur molecules and reaction intermediates (e.g., lithium polysulfide, etc.) dissolve and diffuse into the organic electrolyte during charging and discharging. Therefore, there is a problem that self-discharge and deterioration of the negative electrode are induced, and the battery performance is deteriorated.
Therefore, in order to solve such problems, a method of modifying the electrolyte by adding an acid such as hydrochloric acid or nitric acid to the electrolyte (see Patent Document 1), Ketjenblack as a constituent material of the positive electrode A method using a composite containing sulfur nanoparticles (see Patent Document 2) and the like have been proposed.

JP 2013-114920 A JP 2012-204332 A

However, in the methods disclosed in Patent Documents 1 and 2, since the electrolyte itself is liquid, the dissolution of sulfur molecules and reaction intermediates in the electrolyte cannot be completely suppressed, and sufficient effects cannot be obtained. There was a problem that there was no
A method of using a solid electrolyte is available as a method of solving the problem when using such an electrolytic solution. However, lithium-sulfur solid-state batteries with solid electrolytes have not yet been fully explored technically, and there is considerable room for improvement.

For example, the solid electrolyte is preferably a ceramic material. Various reports have also been made that thinning the solid electrolyte is effective for improving the energy density of the lithium-sulfur solid-state battery. However, since ceramic solid electrolytes are easily cracked, from a practical point of view, the general battery structure uses a plate-like one with a certain thickness to ensure strength.

The problem to be solved by the aspects of the present invention is that the solid electrolyte is less likely to crack even if the solid electrolyte is made thinner, and the lithium-sulfur solid battery, the positive electrode sheet for batteries, the negative electrode sheet for batteries , and the stack can ensure good handleability. It is to provide a layer battery.

In order to solve the above problems, the present invention provides the following aspects.
The lithium-sulfur solid-state battery of the first aspect includes a solid electrolyte formed in a sheet with a thickness of 10 to 500 μm, a flexible sulfur positive electrode formed in a sheet, and a flexible sheet formed in a sheet. a lithium negative electrode; a lithium ion conductive layer disposed between the solid electrolyte and the lithium negative electrode; and the sulfur positive electrode and the lithium disposed on the opposite side of the lithium ion conductive layer with the solid electrolyte interposed therebetween. and a holding member for holding the negative electrode and restricting an increase in the distance between the sulfur positive electrode and the lithium negative electrode, wherein the sulfur positive electrode is formed of a conductive material and has a large number of holes opening on the surface. A conductive sheet and sulfur, a conductive aid, a binder, and an ionic liquid containing only sulfur and an ionic liquid or all of sulfur, a conductive aid, a binder, and an ionic liquid, and are accommodated in the holes of the conductive sheet. The lithium ion conductive layer has a flexible sheet-like main body that is a porous body or a fiber assembly impregnated with an ionic liquid, and the lithium ion conductive layer is a mixture of the lithium negative electrode and the solid electrolyte. It conducts lithium ions between them.
A positive electrode sheet for a battery according to a second aspect includes a solid electrolyte formed in a sheet shape having a thickness of 10 to 500 μm, and the sulfur positive electrode formed in a sheet shape and having flexibility, and the sulfur positive electrode is electrically conductive. A conductive sheet formed of a material and having a large number of holes opening on the surface, and only sulfur and ionic liquid among sulfur, conductive aid, binder and ionic liquid, or all of sulfur, conductive aid, binder and ionic liquid and a positive electrode material accommodated in the hole of the conductive sheet.
The battery negative electrode sheet of the third aspect includes a solid electrolyte formed in a sheet shape with a thickness of 10 to 500 μm, a flexible lithium negative electrode formed in a sheet shape, and between the solid electrolyte and the lithium negative electrode a lithium ion conductive layer disposed in the lithium ion conductive layer, the lithium ion conductive layer is a flexible sheet-like main body portion that is a porous body or a fiber assembly is impregnated with an ionic liquid, and the lithium negative electrode and It has flexibility and conducts lithium ions with the solid electrolyte .
The laminated battery of the fourth aspect is configured by laminating two or more selected from the lithium sulfur solid state battery of the first aspect, the positive electrode sheet for batteries of the second aspect, and the negative electrode sheet for batteries of the third aspect. It is a thing.
The solid electrolyte may be made of an oxide-based material.

According to the lithium-sulfur solid-state battery according to the aspect of the present invention, the sheet-shaped solid electrolyte and the lithium ion conductive layer are sandwiched between the sulfur positive electrode and the lithium negative electrode, so that the solid electrolyte is a sheet-shaped with a thickness of 10 to 500 μm. Even if it is, cracking of the solid electrolyte is less likely to occur. Therefore, the lithium-sulfur solid-state battery according to the aspect of the present invention can ensure good handleability.

A sheet-like solid electrolyte with a thickness of 10 to 500 μm can easily ensure flexibility.
The lithium ion conductive layer can ensure flexibility by a configuration in which a flexible main body portion, which is a porous body or a fiber assembly, is impregnated with an ionic liquid.
For this reason, the lithium-sulfur solid-state battery according to the aspect of the present invention is flexible by a configuration in which a sheet-like solid electrolyte and a lithium ion conductive layer are sandwiched between a flexible sulfur positive electrode and a flexible lithium negative electrode. It is possible to secure the flexibility and to adopt various usage patterns such as curving.

The positive electrode sheet for a battery according to the aspect of the present invention can ensure flexibility due to the flexibility of the sheet-like solid electrolyte and the flexible sheet-like sulfur positive electrode having a thickness of 10 to 500 μm.
The battery negative electrode sheet according to the aspect of the present invention can ensure flexibility by the flexibility of each of the sheet-like solid electrolyte having a thickness of 10 to 500 μm, the lithium ion conductive layer, and the flexible sheet-like lithium negative electrode. .

Lithium-sulfur solid battery, positive electrode sheet for battery, laminated battery configured by stacking two or more selected from negative electrode sheet for battery is selected from lithium-sulfur solid battery, positive electrode sheet for battery, negative electrode sheet for battery, and laminated Size and output can be flexibly adjusted depending on the number of batteries or sheets.

1 is a cross-sectional view schematically showing an example of a main part of a lithium-sulfur solid state battery according to an embodiment of the invention; FIG. 1. It is a perspective view which shows an example of the cylindrical battery with a current collector comprised using the cylindrical battery which wound the lithium-sulfur solid-state battery of FIG. 1 cylindrically, and the cylindrical battery. FIG. 3 is a view showing the structure of the cylindrical battery of FIG. 2 viewed from one side in the axial direction; 4 is a partially enlarged view of the cylindrical battery of FIG. 3; FIG. It is a sectional view showing an example of a positive electrode sheet for batteries. 1 is a cross-sectional view showing an example of a negative electrode sheet for a battery; FIG.

<<Lithium sulfur solid state battery>>
Hereinafter, lithium-sulfur solid state batteries according to embodiments of the present invention will be described 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 front cross-sectional view showing the essential structure of a lithium-sulfur solid-state battery 10 according to one embodiment of the present invention.
A lithium-sulfur solid-state battery 10 shown in FIG.
Solid electrolyte 13 and lithium ion conductive layer 14 are sandwiched between sulfur positive electrode 11 and lithium negative electrode 12 .
Lithium ion conductive layer 14 is sandwiched between solid electrolyte 13 and lithium negative electrode 12 .

In the lithium-sulfur solid-state battery 10 shown in FIG. 1, the sulfur positive electrode 11, the lithium negative electrode 12, and the solid electrolyte 13 are each formed in a flexible sheet shape.
A lithium-sulfur solid-state battery 10 has a structure in which a sulfur positive electrode 11, a solid electrolyte 13, a lithium ion conductive layer 14, and a lithium negative electrode 12 are laminated in this order.

The lithium-ion conductive layer 14 may be a porous material or a fibrous material in which fibrous materials aggregate to form a layer (in this specification, may be referred to as a “fiber assembly”). A flexible sheet-like main body is impregnated with an ionic liquid.
In the present specification, the portion of the lithium ion conductive layer 14 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 14 includes the body portion and the ionic liquid retained by the body portion.

Examples of the flexible sheet-like main body include papers, synthetic resin porous bodies, and fiber aggregates made of synthetic resin or glass fibers. In addition, the main body has a configuration in which a large number of voids penetrating in the thickness direction exist before being impregnated with the ionic liquid.

The thickness direction of the main body coincides with the thickness direction of the lithium ion conductive layer 14 .
The ionic liquid of the lithium ion conductive layer 14 is held in the gaps of the main body.
The void holding the ionic liquid extends from one surface (in this specification, sometimes referred to as "first surface") 14a of lithium ion conductive layer 14 to the other surface (in this specification, " (sometimes referred to as the second surface) 14b.
Therefore, liquid substances and fine substances can be transferred between the lithium negative electrode 12 and the solid electrolyte 13 via the lithium ion conductive layer 14 .

Furthermore, lithium ions can be dissolved in the ionic liquid of the lithium ion conductive layer 14 . Therefore, lithium ions can be easily conducted between the lithium negative electrode 12 and the solid electrolyte 13 (in the direction of the thickness T14 in the lithium ion conductive layer ₁₄ ) through the lithium ion conductive layer 14. there is

In the lithium-sulfur solid-state battery 10, due to the presence of the lithium ion conductive layer 14, the ionic liquid in the lithium ion conductive layer 14 causes the lithium ion conductive layer 14, in other words, between the lithium negative electrode 12 and the solid electrolyte 13, , deposition of metallic lithium is suppressed. Here, "the deposition of metallic lithium is suppressed in the lithium ion conductive layer 14" means "no metallic lithium is deposited in the lithium ion conductive layer 14, or no metallic lithium is deposited in the lithium ion conductive layer 14. Even if it precipitates, the amount of precipitation is very small." Therefore, the lithium ion conductive layer 14 smoothly conducts lithium ions between the lithium negative electrode 12 and the solid electrolyte 13 . Furthermore, by suppressing the deposition of metallic lithium in this way, the deposition of metallic lithium is also suppressed in the solid electrolyte 13 . That is, in the lithium-sulfur solid-state battery 10 , continuous deposition of metallic lithium from the lithium-ion conductive layer 14 to the sulfur positive electrode 11 via the solid electrolyte 13 is suppressed. As a result, in the lithium-sulfur solid-state battery 10, for example, short circuits and cracks in the solid electrolyte can be suppressed during charging and discharging.

In the lithium-sulfur solid-state battery 10, for example, the sulfur positive electrode 11 and the lithium negative electrode 12 are further provided with terminals for connection to external circuits.
In addition, in the lithium-sulfur solid-state battery 10, the entire laminated structure of the sulfur positive electrode 11, the solid electrolyte 13, the lithium ion conductive layer 14 and the lithium negative electrode 12 is housed in a container, if necessary.
In addition, the lithium-sulfur solid-state battery 10 further optionally has a mechanism (leakage suppression mechanism) that suppresses leakage of the ionic liquid in the lithium-ion conductive layer 14 to the outside of the lithium-sulfur solid-state battery 10. good too. 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.

First, the sulfur positive electrode will be described in detail.
The sulfur positive electrode in the lithium-sulfur solid-state battery of the present embodiment is not particularly limited as long as it contains sulfur and functions as a positive electrode.

However, a preferable sulfur positive electrode 11 includes a conductive sheet having a large number of holes opening on the surface thereof, and a positive electrode material accommodated in the holes of the conductive sheet.
A flexible conductive sheet is used. The sulfur positive electrode 11 in which the positive electrode material is accommodated in the holes of the conductive sheet is formed in a flexible sheet shape.

The positive electrode material contains only sulfur among sulfur, a conductive aid, a binder and an ionic liquid, a material containing only sulfur and an ionic liquid, or a material containing all of sulfur, a conductive aid, a binder and an ionic liquid. is.
The positive electrode material may be present covering not only the holes of the conductive sheet but also a part or the whole of the outer peripheral surface of the conductive sheet.
These constituent materials of the sulfur positive electrode will be described in detail below.
First, a sulfur positive electrode having a positive electrode material containing all of sulfur, a conductive aid, a binder and an ionic liquid will be described.

[Conductive sheet]
The holes in the conductive sheet hold the constituent components of the sulfur positive electrode other than the conductive sheet, that is, the positive electrode material. And the conductive sheet can function as a positive electrode current collector.
In addition, the holes of the conductive sheet are open on the surface of the conductive sheet, and by adding each component such as sulfur to the conductive sheet later, it is possible to retain these components. there is

The shape of the holes in the conductive sheet is not particularly limited as long as the above conditions are satisfied.
For example, a hole may communicate with one or more other holes, or may be independent without communicating with other holes.
Moreover, the hole may penetrate the conductive sheet, or may not penetrate the conductive sheet.

Examples of the form of the conductive sheet include a fiber aggregate (a fibrous material in which conductive fibrous materials are aggregated to form a layer).
The fiber assembly that constitutes the conductive sheet may be, for example, a structure in which fibrous materials are entangled with each other, or a structure in which fibrous materials are regularly or irregularly stacked. may
The holes of the conductive sheet, which is a fiber assembly, refer to those regions, such as regions between fibrous materials that are spaced apart from each other, in which fibrous material does not exist in the fiber assembly and that are open to the surface of the conductive sheet.

The holes of the conductive sheet may be filled with the positive electrode material without gaps, or there may be some gaps that are not filled with the positive electrode material.
A sulfur positive electrode containing a conductive sheet that is a fiber assembly has a configuration in which a fibrous material that constitutes the fiber assembly is embedded in a positive electrode material filled in a region in the fiber assembly where the fibrous material does not exist. .

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, the combination and ratio thereof can be arbitrarily selected according to the purpose.

Preferred conductive sheets include, for example, carbon felt and carbon cloth.

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 50-30000 μm, more preferably 100-3000 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 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 (sulfur positive electrode, lithium negative electrode, solid electrolyte, which will be described later).

[Conductive agent]
The conductive aid may be a known one, and specific examples thereof include graphite; carbon black such as ketjen black and acetylene black; carbon nanotube; graphene; fullerene and the like.
The conductive aid contained in the sulfur positive electrode 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.

In the sulfur positive electrode, the ratio of the total content of sulfur and conductive aid to the total content of sulfur, conductive aid, binder and ionic liquid ([total content of sulfur and conductive aid in sulfur positive electrode (parts by mass)] /[Total content of sulfur, conductive aid, binder and ionic liquid in sulfur positive electrode (parts by mass)] × 100) is not particularly limited, but is preferably 60 to 95% by mass, preferably 70 to 85% by mass. is more preferable. When the ratio of the total content is equal to or higher than the lower limit, the charge/discharge characteristics of the battery are further improved. When the ratio of the total content is equal to or less than the upper limit, the effect of using components other than sulfur and the conductive aid can be obtained more remarkably.

In the sulfur positive electrode, the mass ratio of [sulfur content (parts by mass)]:[conductivity aid content (parts by mass)] is not particularly limited, but is preferably 30:70 to 70:30, It is more preferably 45:55 to 65:35. The higher the sulfur content ratio, the better the charge/discharge characteristics of the battery, and the higher the conductive aid content ratio, the better the conductivity of the sulfur positive electrode.

In the sulfur positive electrode, sulfur and the conductive aid may form a composite.
For example, a sulfur-carbon composite can be obtained by mixing sulfur and a carbon-containing material (eg, Ketjenblack, etc.) and firing the mixture. Such a composite is also suitable as a component contained in the sulfur positive electrode.

[binder]
The binder may be a known one, and specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-propylene hexafluoride copolymer (PVDF-HFP), polyacrylic acid (PAA), Polylithium acrylate (PAALi), styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), polyethylene oxide (PEO), polyethylene glycol (PEG), carboxymethylcellulose (CMC), polyacrylonitrile (PAN), polyimide (PI) etc.
The binder contained in the sulfur positive electrode may be of one type or two or more types, and when there are two or more types, the combination and ratio thereof can be arbitrarily selected according to the purpose.

In the sulfur positive electrode, the ratio of the content of the binder to the total content of sulfur, conductive aid, binder and ionic liquid ([binder content of sulfur positive electrode (parts by mass)] / [sulfur positive electrode, conductive aid , total content of binder and ionic liquid (parts by mass)]×100) is not particularly limited, but is preferably 3 to 15% by mass, more preferably 5 to 9% by mass. When the content ratio is equal to or higher than the lower limit, the structure of the sulfur positive electrode can be more stably maintained. When the content ratio is equal to or less than the upper limit, the charge/discharge characteristics of the battery are further improved.

[Ionic liquid]
The ionic liquid contained in the sulfur positive electrode is a component for easily moving lithium ions. The ionic liquid has excellent high-temperature stability and can easily move lithium ions. Since the sulfur positive electrode contains the ionic liquid, although the contact area between the sulfur positive electrode and the solid electrolyte is small, the ionic liquid moves lithium ions between the sulfur positive electrode and the solid electrolyte. Therefore, a solid battery using such a sulfur positive electrode has a smaller interfacial resistance value at the interface of the sulfur positive electrode, and has better battery characteristics, in spite of using a solid electrolyte.

The ionic liquid can be appropriately selected from known ones, for example.
However, the ionic liquid preferably has a lower solubility of sulfur in a temperature range of, for example, less than 170° C., and particularly preferably does not dissolve sulfur.

Examples of ionic liquids include ionic compounds that are liquid at a temperature of less than 170° C., solvated ionic liquids, and the like.

(Ionic compound liquid at a temperature of less than 170°C)
The cation moiety constituting the ionic compound may be either an organic cation or an inorganic cation, but is preferably an organic cation.
The anion part constituting the ionic compound may be either an organic anion or an inorganic anion.

Among the cation moieties, organic cations include, for example, imidazolium cation, pyridinium cation, pyrrolidinium cation, phosphonium cation, and ammonium cation. , sulfonium cation, and the like.
However, the organic cation is not limited to these.

Among the anion moieties, organic anions include alkylsulfate anions such as methylsulfate anion (CH ₃ SO ₄ ⁻ ) and ethylsulfate anion (C ₂ H ₅ SO ₄ ⁻ );
Tosylate anion (CH ₃ C ₆ H ₄ SO ₃ ⁻ );
alkanesulfonate anions such as methanesulfonate anion (CH ₃ SO ₃ ⁻ ), ethanesulfonate anion (C ₂ H ₅ SO ₃ ⁻ ), butanesulfonate anion (C ₄ H ₉ SO ₃ ⁻ );
trifluoromethanesulfonate anion (CF ₃ SO ₃ ⁻ ), pentafluoroethanesulfonate anion (C ₂ F ₅ SO ₃ ⁻ ), heptafluoropropanesulfonate anion (C ₃ H ₇ SO ₃ ⁻ ), nonafluorobutanesulfonate anion (C ₄ perfluoroalkanesulfonate anions such as H ₉ SO ₃ ⁻ );
Bis(trifluoromethanesulfonyl)imide anion ((CF ₃ SO ₂ )N ⁻ ), bis(nonafluorobutanesulfonyl)imide anion ((C ₄ F ₉ SO ₂ )N ⁻ ), nonafluoro-N-[(trifluoromethane) sulfonyl]butanesulfonylimide anion ((CF ₃ SO ₂ )(C ₄ F ₉ SO ₂ )N ⁻ ), N,N-hexafluoro-1,3-disulfonylimide anion (SO ₂ CF ₂ CF ₂ CF ₂ SO ₂ N ⁻ ) and other perfluoroalkanesulfonylimide anions;
Acetate anion (CH ₃ COO ⁻ );
hydrogen sulfate anion (HSO ₄ ⁻ ); and the like.
However, the organic anions are not limited to these.

Among the anion moieties, inorganic anions include, for example, bis(fluorosulfonyl)imide anion (N(SO ₂ F) ₂ ⁻ ); hexafluorophosphate anion (PF ₆ ⁻ ); tetrafluoroborate anion (BF ₄ ⁻ ). ; halide anions such as chloride ion (Cl ^- ), bromide ion (Br ^- ), iodide ion (I ^- ); tetrachloroaluminate anion (AlCl ₄ ^- ), thiocyanate anion (SCN ^- ), etc. is mentioned.
However, the inorganic anions are not limited to these.

Examples of the ionic compound include those composed of a combination of any of the above cation moieties and any of the above anion moieties.

Examples of the ionic liquid whose cation moiety is an imidazolium cation include 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1 -methyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium chloride, 1-butyl-3- Methylimidazolium chloride, 1-ethyl-3-methylimidazolium methanesulfonate, 1-butyl-3-methylimidazolium methanesulfonate, 1,2,3-trimethylimidazolium methylsulfate, methylimidazolium chloride, methylimidazolium hydrochloride Gensulfate, 1-ethyl-3-methylimidazolium hydrogensulfate, 1-butyl-3-methylimidazolium hydrogensulfate, 1-butyl-3-methylimidazolium hydrogensulfate, 1-ethyl-3-methylimidazolium Lithium tetrachloroaluminate, 1-butyl-3-methylimidazolium tetrachloroaluminate, 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium Lithium ethyl sulfate, 1-butyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium thiocyanate, 1-butyl-3-methylimidazolium thiocyanate, 1-ethyl-2,3-dimethylimidazolium ethyl sulfate and the like.

Examples of ionic liquids in which the cation moiety is a pyridinium cation include 1-butylpyridinium bis(trifluoromethanesulfonyl)imide and 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide.

Ionic liquids in which the cation moiety is a pyrrolidinium cation include, for example, 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide and the like.

Examples of ionic liquids in which the cation moiety is a phosphonium cation include tetrabutylphosphonium bis(trifluoromethanesulfonyl)imide and tributyldodecylphosphonium bis(trifluoromethanesulfonyl)imide.

Examples of ionic liquids in which the cation moiety is an ammonium cation include methyltributylammonium methylsulfate, butyltrimethylammonium bis(trifluoromethanesulfonyl)imide, and trimethylhexylammonium bis(trifluoromethanesulfonyl)imide.

(solvated ionic liquid)
Preferred solvated ionic liquids include, for example, those comprising a glyme-lithium salt complex.

Examples of the lithium salt in the glyme-lithium salt complex include lithium bis(fluorosulfonyl)imide (LiN(SO ₂ F) ₂ , herein sometimes abbreviated as “LiFSI”), lithium bis ( trifluoromethanesulfonyl)imide (LiN(SO ₂ CF ₃ ) ₂ , sometimes abbreviated as “LiTFSI” in this specification), and the like.

Examples of glyme in the glyme-lithium salt complex include triethylene glycol dimethyl ether (CH ₃ (OCH ₂ CH ₂ ) ₃ OCH ₃ , triglyme), tetraethylene glycol dimethyl ether (CH ₃ (OCH ₂ CH ₂ ) ₄ OCH ₃ , tetraglyme) and the like.

Examples of the glyme-lithium salt complex include a complex composed of one glyme molecule and one lithium salt molecule, but the glyme-lithium salt complex is not limited thereto.

The glyme-lithium salt complex is obtained, for example, by mixing a lithium salt and glyme such that the molar ratio of lithium salt (mol): glyme (mol) is preferably 10:90 to 90:10. can be made.

Preferred glyme-lithium salt complexes include, for example, triglyme-LiFSI complex, tetraglyme-LiFSI complex, triglyme-LiTFSI complex, tetraglyme-LiTFSI complex, and the like.

The ionic liquids contained in the sulfur positive electrode may be of one type or two or more types, and when there are two or more types, the combination and ratio thereof can be arbitrarily selected according to the purpose.

The ionic liquid contained in the sulfur positive electrode is preferably a solvated ionic liquid comprising a glyme-lithium salt complex among the above.

In the sulfur positive electrode, the ratio of the content of the ionic liquid to the total content of sulfur, conductive aid, binder and ionic liquid ([content of the ionic liquid of the sulfur positive electrode (parts by mass)] / [sulfur of the sulfur positive electrode, conductivity The total content of auxiliary agent, binder and ionic liquid (parts by mass)]×100) is not particularly limited, but is preferably 5 to 20% by mass, more preferably 9 to 15% by mass. When the content ratio is equal to or higher than the lower limit value, the conductivity of the sulfur positive electrode is further improved. When the content ratio is equal to or less than the upper limit, the charge/discharge characteristics of the battery are further improved.

[Other ingredients]
The sulfur positive electrode contains other components (excluding the solvent described later) in addition to sulfur, a conductive aid, a binder, and an ionic liquid as constituent components other than the conductive sheet within a range that does not impair the effects of the present invention. may contain.
The other components are not particularly limited and can be arbitrarily selected according to the purpose.
The other components contained in the sulfur positive electrode may be of one type or two or more types, and when there are two or more types, the combination and ratio thereof can be arbitrarily selected according to the purpose.

In the sulfur positive electrode, the ratio of the content of the other components to the total content of sulfur, conductive aid, binder and ionic liquid ([content of other components of the sulfur positive electrode (parts by mass)] / [of the sulfur positive electrode The total content of sulfur, conductive aid, binder and ionic liquid (parts by mass)] × 100) is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, It is more preferably 3% by mass or less, particularly preferably 1% by mass or less, and may be 0% by mass.

In the sulfur positive electrode, the ratio of the total mass of sulfur, conductive aid, binder and ionic liquid to the mass of the conductive sheet ([total mass of sulfur, conductive aid, binder and ionic liquid] / [mass of conductive sheet] ×100) is preferably 15 to 45% by mass, more preferably 25 to 40% by mass.

<Method for producing sulfur positive electrode>
A known sulfur positive electrode, such as the above-described sulfur positive electrode configured by providing a positive electrode active material layer on a current collector (positive electrode current collector), may be produced by a known method.
On the other hand, the sulfur positive electrode provided with the conductive sheet is manufactured by impregnating the conductive sheet with a positive electrode material (positive electrode material forming composition) containing, for example, sulfur, a conductive aid, a binder and an ionic liquid. method can be manufactured. The manufacturing method may further include other steps such as a step of drying the impregnated positive electrode material-forming composition.
However, in this method for producing a sulfur positive electrode, if the positive electrode material-forming composition impregnated into the conductive sheet contains an organic solvent that generates a combustible gas, the step of impregnating the conductive sheet with the positive electrode material-forming composition is performed. Afterwards, the organic solvent that generates combustible gas is removed from the positive electrode material-forming composition by a drying process, distillation, or the like.
A method for producing such a sulfur positive electrode will be described below.

[Cathode material]
Preferred positive electrode material-forming compositions include, for example, those containing sulfur, a conductive aid, a binder, an ionic liquid, a solvent, and, if necessary, the above other components.

The solvent is a component for dissolving or dispersing each component such as sulfur described above and imparting appropriate fluidity to the positive electrode material-forming composition.
In this specification, unless otherwise specified, any ionic liquid is not included in the solvent (all ionic liquids are not treated as solvents).

The solvent can be arbitrarily selected according to the type of each component such as sulfur described above, and organic solvents are preferred.
Examples of the organic solvent include alcohols such as methanol, ethanol, 1-propanol and 2-propanol; amides such as N-methylpyrrolidone (NMP) and N,N-dimethylformamide (DMF); ketones such as acetone. mentioned.
The solvent contained in the positive electrode material (positive electrode material-forming composition) may be of one type or two or more types, and when there are two or more types, the combination and ratio thereof can be arbitrarily selected according to the purpose. .
The content of the solvent in the positive electrode material-forming composition is not particularly limited, and can be adjusted as appropriate according to the types of components other than the solvent.

The ratio of the sulfur content to the total content of components other than the solvent in the positive electrode material ([content of sulfur in the positive electrode material (mass)] / [total content of components other than the solvent in the positive electrode material (parts by mass )] × 100) is the ratio of sulfur content to the total content of sulfur, conductive aid, binder, ionic liquid and other components in the sulfur positive electrode ([sulfur content of sulfur positive electrode (parts by mass )]/[total content of sulfur, conductive aid, binder, ionic liquid and other components in the sulfur positive electrode (parts by mass)]×100). This is the same for conductive aids, binders, ionic liquids and other components other than sulfur.

The positive electrode material-forming composition is obtained by blending each component such as sulfur described above.
There are no particular restrictions on the order of addition of each component when blending, and two or more components may be added at the same time.
When using a solvent, the solvent is mixed with any component other than the solvent (that is, any component of the above sulfur, conductive aid, binder, ionic liquid and other components), and this component is It may be used by diluting in advance, or may be used by mixing the solvent with any of the components other than the above-mentioned solvent without diluting them in advance.

The method of mixing each component at the time of blending is not particularly limited, and known methods include 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. method can be selected as appropriate.
The temperature and time during the addition and mixing of each component are not particularly limited as long as each component does not deteriorate. Generally, the temperature during mixing is preferably 15 to 30°C.

The positive electrode material-forming composition obtained by adding and mixing each component may be used as it is for impregnating the conductive sheet, or for example, by removing a part of the added solvent by distillation or the like. The result of additional operations may be used to impregnate the conductive sheet.

The impregnation of the conductive sheet with the positive electrode material-forming composition is performed by, for example, a method of coating the conductive sheet with the positive electrode material-forming composition in a liquid state, a method of immersing the conductive sheet in the positive electrode material in a liquid state, or the like. It can be carried out.
The positive electrode material-forming composition can be applied to the conductive sheet by a known method.
Although the temperature of the positive electrode material impregnated into the conductive sheet is not particularly limited, it can be, for example, 15 to 30.degree. However, this is an example of said temperature.

Drying of the positive electrode material-forming composition can be performed under normal pressure or reduced pressure by a known method. For example, it is preferably dried under conditions of 70 to 90° C. for 8 to 24 hours, but the drying conditions are not limited thereto.
The sulfur positive electrode is used in the assembly of the lithium-sulfur solid-state battery 10 after removing the organic solvent from the positive electrode material-forming composition impregnated in the conductive sheet by drying, distillation, or the like.

Next, a sulfur positive electrode having a positive electrode material containing only sulfur out of sulfur, a conductive aid, a binder, and an ionic liquid in the holes of the conductive sheet will be described.
In this method for producing a sulfur positive electrode, hot molten sulfur or a sulfur solution obtained by dissolving sulfur in a solvent is filled into the holes of the conductive sheet to impregnate the conductive sheet. When the conductive sheet is impregnated with sulfur in a hot molten state, the sulfur in the hot molten state impregnated in the conductive sheet is cooled and solidified to obtain a sulfur positive electrode in which sulfur is contained in the holes.
When the conductive sheet is impregnated with the sulfur solution, the conductive sheet is impregnated with the sulfur solution, and then the solvent is removed in a drying process to obtain a sulfur positive electrode having a structure in which sulfur is contained in the holes. .

Next, a sulfur positive electrode having a positive electrode material containing only sulfur and an ionic liquid out of sulfur, a conductive aid, a binder, and an ionic liquid in the holes of the conductive sheet will be described.
The ionic liquid of the positive electrode material can be the same as the ionic liquid that can be used in the positive electrode material containing all of sulfur, a conductive aid, a binder and an ionic liquid.

An example of a method for producing a sulfur positive electrode having this positive electrode material is to first produce a sulfur positive electrode having a positive electrode material containing only sulfur among sulfur, a conductive aid, a binder, and an ionic liquid in a hole of a conductive sheet. Next, by immersing the sulfur positive electrode in the ionic liquid, applying the ionic liquid to the sulfur positive electrode, etc., the ionic liquid is filled in the voids in the holes of the conductive sheet that are not filled with sulfur, and the holes are filled with the ionic liquid. A sulfur positive electrode having a structure containing sulfur and an ionic liquid is obtained.
However, in this method for producing a sulfur positive electrode, the gaps in the holes of the conductive sheet may be filled with a mixture of the ionic liquid and the solvent. When using a mixture of an ionic liquid and an organic solvent that generates a combustible gas, after impregnating the conductive sheet with the mixture, remove the organic solvent from the mixture by drying or distillation. do.

Regardless of the type of sulfur positive electrode, the thickness of the sulfur positive electrode is not particularly limited, and may be appropriately set according to the purpose of the battery to which it is applied. The thickness of the sulfur positive electrode is preferably 50-30000 μm, more preferably 100-3000 μm.

Next, the solid electrolyte 13 will be explained.
The constituent material of the solid electrolyte 13 may be any of a crystalline material, an amorphous material, and a glass material.
More specifically, the constituent material of the solid electrolyte 13 is, 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 a sulfide (which may be referred to herein as a “sulfide-based material”) and other known 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 Ti1.46 ( PO4} ) _{3 , Li1.5Al0.5Ge1.5 ( PO4 ) 3 , Li5La3Ta2O12 , Li0.33La0.55TiO3 (} LLT) 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, only one element or two or more elements may be added, and when two or more elements are added, the combination and ratio thereof can be arbitrarily selected according to the purpose.

Examples of the _{sulfide -} based material _{include Li10GeP2S12 ( LGPS} ), _{Li3.25Ge0.25P0.75S4 , 30Li2S.26B2S3.44LiI} , _{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 13 may be of one type or two or more types, and when there are two or more types, their combination and ratio can be arbitrarily selected according to the purpose.

The constituent material of the solid electrolyte 13 is preferably the above-described oxide-based material because it has high stability in the air and can produce a highly dense solid electrolyte 13 .

The thickness of the solid electrolyte 13 is not particularly limited, and may be appropriately set according to the purpose of the battery to be applied. The thickness of the solid electrolyte 13 is preferably 10-1200 μm. When the thickness of the solid electrolyte is equal to or greater than the lower limit, the manufacturing and handling properties thereof are further improved. When the thickness of the solid electrolyte is equal to or less than the upper limit, the resistance value of the lithium-sulfur solid-state battery is further reduced.

The solid electrolyte 13 can be manufactured by, for example, 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 13 and the like.

The solid electrolyte 13 is manufactured, for example, by sintering a molded body obtained by compacting a powdery material. As a method for producing the solid electrolyte 13, for example, a plurality of sheets produced by compacting a powdery material (hereinafter also referred to as compacted powder sheets) can be stacked, fired, and integrated.
In addition, the solid electrolyte 13 is formed by applying a composition obtained by dispersing the powder of the raw material after firing in a solvent to the sulfur positive electrode 11 or the main body portion of the lithium ion conductive layer 14 before impregnation with the ionic liquid and drying it. Separately, it is also possible to apply the composition to an object to be coated, such as a board, and dry the layered product, which is peeled off from the object to be coated. It is also possible to add a binder, an electrolytic solution, or the like to the composition according to the purpose.

The sheet-like solid electrolyte 13 with a thickness of 10 to 500 μm can ensure flexibility.
In addition, the solid electrolyte 13 is sandwiched between the flexible sheet-like sulfur positive electrode 11 and the flexible sheet-like lithium negative electrode 12 together with the flexible lithium ion conductive layer 14, so that the solid electrolyte 13 can be curved. It is hard to break and can be curved so as to follow the sulfur positive electrode 11 , the lithium negative electrode 12 and the lithium ion conductive layer 14 .

The lithium negative electrode 12 can be a well-known lithium negative electrode used in various batteries.
The thickness of the lithium negative electrode is preferably 10 to 2000 μm, more preferably 100 to 1000 μm, in consideration of bending flexibility.

Next, the lithium ion conductive layer 14 will be described.
As described above, the lithium ion conductive layer in the lithium-sulfur solid-state battery of the present embodiment is a layer that contains an ionic liquid and conducts lithium ions between the lithium negative electrode and the solid electrolyte.
As described above, the lithium ion conductive layer includes a main body and an ionic liquid.

[Body part]
As described above, the body portion of the lithium ion conductive layer includes a porous body, a fiber assembly, and the like.
The body portion of the lithium ion conductive layer preferably does not react with, dissolve, or degrade with the lithium negative electrode under the temperature conditions during operation of the lithium-sulfur solid-state battery. 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 can be appropriately set according to the type of sulfur positive electrode. When a known sulfur positive electrode or sulfur positive electrode (I) is used, the operating temperature of the lithium-sulfur solid state battery is, for example, preferably 110° C. or lower, more preferably 100° C. or lower. Therefore, the body of the lithium ion conductive layer in this case is preferably stable under temperature conditions of, for example, about 120.degree. On the other hand, when the sulfur positive electrode (II) is used, the operating temperature of the lithium sulfur solid state battery is preferably 110 to 160°C. Therefore, the body of the lithium ion conductive layer in this case is preferably stable under such temperature conditions.

Among such main bodies, the constituent material of the porous body or fiber assembly includes, for example, synthetic resin, glass, paper, etc., and is preferably synthetic resin or glass.
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 the same ionic liquids contained in the sulfur positive electrode described above (eg, ionic compounds that are liquid at a temperature of less than 170° C., solvated ionic liquids, 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 is further 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 deposition of metallic lithium in the solid electrolyte becomes higher. 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, "multiple 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 (for example, in the case of the lithium-sulfur solid state battery 10 shown in FIG. 1, the thickness T ₁₄ of the lithium ion conductive layer 14) 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 from the point of view that the effect of suppressing deposition of metallic lithium in the solid electrolyte becomes higher. When the thickness of the lithium ion conductive layer is equal to or greater than the lower limit, metallic lithium will not precipitate in the lithium ion conductive layer, or even if a trace amount of metallic lithium precipitates in the lithium ion conductive layer, The influence does not extend to the solid electrolyte. As a result, in the lithium-sulfur solid-state battery, continuous deposition of metallic lithium from the lithium-ion conductive layer through the solid electrolyte to the sulfur positive electrode 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 conducting layer, the lower the resistance across the lithium ion conducting layer and the higher the energy density of the lithium sulfur solid state battery.

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 15-50° C., but this is an example. The method of mixing each raw material may be the same as the method of mixing each component in the production of the positive electrode material described above, for example.

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 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 to 100° C., but this is just 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 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, if the surface to be formed of 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 by, for example, impregnating the main body with an ionic liquid, or 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 liquid 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 to 50° C., but this is an example.

Drying of the main body after being impregnated with the mixed solution 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 to 100° C., but this is just an example.

The lithium-sulfur solid-state battery 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 above-described ones without departing from the spirit of the present invention. may be

For example, the lithium-sulfur solid-state battery of the present embodiment includes one or more other layers that do not correspond to any of the sulfur positive electrode, the solid electrolyte, the lithium ion conductive layer, and the lithium negative electrode, 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.

For example, a separator may be provided between the sulfur positive electrode 11 and the solid electrolyte 13 to stabilize the amount of lithium ions moving from the solid electrolyte 13 to the sulfur positive electrode 11 side.

As a configuration for providing the other layer, a gold sputtered layer is arranged between the sulfur positive electrode and the solid electrolyte, and these three layers are in this order and in direct contact with each other. The interfacial resistance value at the sulfur positive electrode interface is reduced as compared with the case where the sputtered layer is not arranged. For example, when the sulfur positive electrode is a known one configured by providing a positive electrode active material layer on a current collector (positive electrode current collector), such an effect of reducing the interfacial resistance value is more remarkable. Become.
In this case, the thickness of the sputtered gold layer is preferably 50 nm or more, more preferably 100 to 200 nm.

However, when using a sulfur positive electrode configured to contain a component such as sulfur in the voids of a conductive sheet having a large number of voids, in the lithium-sulfur solid battery of the present embodiment, the sulfur positive electrode, It is preferred that the solid electrolyte, the lithium ion conducting layer and the lithium negative electrode, in this order, are in direct contact with each other (not provided with said other layers).

As shown in FIG. 1, the holding member 15 collectively holds the sulfur positive electrode 11, the solid electrolyte 13, the lithium ion conductive layer 14, and the lithium negative electrode 12, thereby increasing the separation distance between the sulfur positive electrode 11 and the lithium negative electrode 12. It is a member that regulates
In the holding member 15 shown in FIG. 1, a laminate 16 (a sheet-like laminate, hereinafter also referred to as a laminate sheet) of the sulfur positive electrode 11, the solid electrolyte 13, the lithium ion conductive layer 14, and the lithium negative electrode 12 is provided. is formed with a laminate fitting groove 15a into which is fitted. The holding member 15 holds the laminated body sheet 16 inserted and fitted into the laminated body fitting groove 15 a to restrict an increase in the separation distance between the sulfur positive electrode 11 and the lithium negative electrode 12 .

The holding member 15 can preferably be made of a material such as rubber, synthetic resin, etc., having electrical insulation and liquid-blocking properties.
Holding member 15 having a liquid-impervious property also serves as a sealing material that prevents the ionic liquid from leaking from the outer peripheral edge of laminate sheet 16 by being fitted to laminate sheet 16 .

<<Method for producing lithium-sulfur solid-state battery>>
In the lithium-sulfur solid-state battery of the present embodiment, the solid electrolyte is positioned between the sulfur positive electrode and the lithium negative electrode, and the lithium ion conductive layer is positioned between the solid electrolyte and the lithium negative electrode, It can be manufactured by a method including a step of arranging the sulfur positive electrode, the lithium negative electrode, the solid electrolyte and the lithium ion conductive layer.
In other words, the lithium-sulfur solid-state battery of the present embodiment can be manufactured by a method having a step of laminating the sulfur positive electrode, the solid electrolyte, the lithium ion conductive layer and the lithium negative electrode in this order in the thickness direction.
For example, the lithium-sulfur solid-state battery of the present embodiment uses a new lithium ion conductive layer, and the sulfur positive electrode, the solid electrolyte, the lithium ion conductive layer, and the lithium negative electrode are laminated in the above-described arrangement. It can be manufactured in the same way as for lithium-sulphur solid-state batteries. In the case of using the sulfur positive electrode provided with the above-described conductive sheet, the sulfur positive electrode is additionally used instead of the conventional sulfur positive electrode, except that such a sulfur positive electrode is used. can be produced in the same manner as

The handling temperature of the lithium-sulfur solid-state battery of the present embodiment is preferably 110° C. or lower, more preferably 100° C. or lower. By doing so, vaporization of the ionic liquid can be suppressed, leakage of sulfur can be suppressed, and the lithium-sulfur solid-state battery exhibits better battery characteristics.

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

Since the lithium-sulfur solid-state battery 10 (specifically, its laminate sheet 16) is flexible, it can be rolled into a cylindrical shape as shown in FIGS. 2 and 3, for example.
2 and 3 show a tubular battery 17 formed by a lithium-sulfur solid state battery 10 rolled into a cylinder.

The cylindrical battery 17 shown in FIGS. 2 and 3 is obtained by winding the lithium-sulfur solid-state battery 10 so that the sulfur positive electrode 11 is on the outer peripheral side and the lithium negative electrode 12 is on the inner peripheral side. Further, as shown in FIGS. 3 and 4, adjacent portions of the lithium-sulfur solid-state battery 10 constituting the cylindrical battery 17 in the radial direction of the cylindrical battery 17 are in contact with each other. Therefore, in cylindrical battery 17, sulfur positive electrode 11 and lithium negative electrode 12 of lithium-sulfur solid-state battery 10 are in contact with each other over a wide range. As a result, in the cylindrical battery 17, the energy density can be easily improved as compared with the case where the lithium-sulfur solid state battery 10 is used in the flat state.

The cylindrical battery 17 can also adopt a configuration in which the lithium-sulfur solid-state battery 10 is wound with the sulfur positive electrode 11 on the inner peripheral side and the lithium negative electrode 12 on the outer peripheral side.

FIG. 2 is also a diagram showing an example of a battery 18 with a current collector configured using the cylindrical battery 17. As shown in FIG.
The battery 18 with a current collector in FIG. 17 and a tubular outer current collector 18 b that contacts the side peripheral surface of the tubular battery 17 .
Examples of materials for the inner current collector 18a and the outer current collector 18b include carbon, copper, aluminum, titanium, nickel, and stainless steel. The inner current collector 18a is formed in a bar shape.
Of the inner current collector 18a and the outer current collector 18b, those in contact with the sulfur positive electrode 11 function as positive electrode current collectors, and those in contact with the lithium negative electrode 12 function as negative electrode current collectors.

The inner current collector 18a may have a hollow rod shape (cylindrical shape) as well as a solid rod shape.
The outer current collector 18b is not limited to a cylindrical shape that accommodates the cylindrical battery 17, and may have various configurations as long as it can contact and abut on the side peripheral surface of the cylindrical battery 17. It is possible.

FIG. 5 shows a sheet-shaped solid electrolyte 13 (hereinafter also referred to as an electrolyte sheet) having a thickness of 10 to 500 μm, a flexible sheet-shaped sulfur positive electrode 11 (hereinafter also referred to as a sulfur positive electrode sheet), a sulfur positive electrode sheet 11 and A battery positive electrode sheet 20 configured by a holding member (not shown) that holds the outer peripheral portion of the electrolyte sheet 13 and maintains the overlapping state of the sulfur positive electrode sheet 11 and the electrolyte sheet 13 is shown.
As the sulfur positive electrode sheet 11 and the electrolyte sheet 13, the same materials as those described in the lithium-sulfur solid state battery 10 can be used.
The battery positive electrode sheet 20 has flexibility.

In FIG. 6, the lithium ion conductive layer 14 is sandwiched between the electrolyte sheet 13 and the flexible sheet-shaped lithium negative electrode 12 (hereinafter also referred to as negative electrode sheet), and the outer peripheral portions of the electrolyte sheet 13 and the negative electrode sheet 12 are held. 3 shows a battery negative electrode sheet 30 having a configuration in which a holding member (not shown) for maintaining a state in which the lithium ion conductive layer 14 is sandwiched between the electrolyte sheet 13 and the flexible sheet-like negative electrode sheet 12 is provided.
As the negative electrode sheet 12, the electrolyte sheet 13, and the lithium ion conductive layer 14, the same materials as those described in the lithium-sulfur solid state battery 10 can be used.
The battery negative electrode sheet 30 has flexibility.

The lithium-sulfur solid-state battery 10, the positive electrode sheet for battery 20, and the negative electrode sheet for battery 30 can be used for assembling a laminated battery by laminating two or more selected from these.

DESCRIPTION OF SYMBOLS 10... Lithium sulfur solid state battery, 11... Sulfur positive electrode, 12... Lithium negative electrode, 13... Solid electrolyte, 14... Lithium ion conductive layer, 15... Holding member, 16... Laminate sheet, 17... Cylindrical battery, 18... Current collector Body-attached battery 18a...Inner current collector 18b...Outside current collector 20...Battery positive electrode sheet 30...Battery negative electrode sheet.

Claims (7)

A sheet-shaped solid electrolyte having a thickness of 10 to 500 μm, a sheet-shaped flexible sulfur positive electrode, a sheet-shaped flexible lithium negative electrode, the solid electrolyte and the lithium negative electrode. and the sulfur positive electrode and the lithium negative electrode arranged on the opposite side of the lithium ion conductive layer with the solid electrolyte interposed therebetween, holding the sulfur positive electrode and the lithium ion conductive layer a holding member that regulates an increase in the distance from the lithium negative electrode,
The sulfur positive electrode includes a conductive sheet formed of a conductive material and having a large number of holes opening on the surface, sulfur, a conductive aid, a binder and an ionic liquid, sulfur and the ionic liquid alone or sulfur, the conductive aid, A positive electrode material containing all of a binder and an ionic liquid and accommodated in the hole of the conductive sheet,
The lithium ion conductive layer has a flexible sheet-like main body that is a porous body or a fiber assembly impregnated with an ionic liquid, and conducts lithium ions between the lithium negative electrode and the solid electrolyte. Lithium-sulfur solid-state battery. A flexible battery positive electrode sheet having a sulfur positive electrode,
A solid electrolyte formed in a sheet with a thickness of 10 to 500 μm and the flexible sulfur positive electrode formed in a sheet,
The sulfur positive electrode includes a conductive sheet formed of a conductive material and having a large number of holes opening on the surface, sulfur, a conductive aid, a binder and an ionic liquid, sulfur and the ionic liquid alone or sulfur, the conductive aid, A flexible positive electrode sheet for a battery, containing all of a binder and an ionic liquid, and having a positive electrode material accommodated in the holes of the conductive sheet. A flexible battery negative electrode sheet having a lithium negative electrode, comprising:
A solid electrolyte formed in a sheet shape with a thickness of 10 to 500 μm, a flexible lithium negative electrode formed in a sheet shape, and a lithium ion conductive layer disposed between the solid electrolyte and the lithium negative electrode. prepared,
The lithium ion conductive layer has a flexible sheet-like main body that is a porous body or a fiber assembly impregnated with an ionic liquid, and conducts lithium ions between the lithium negative electrode and the solid electrolyte. A flexible negative electrode sheet for a battery. A laminated battery comprising two or more layers selected from the lithium-sulfur solid-state battery according to claim 1, the positive electrode sheet for a battery according to claim 2, and the negative electrode sheet for a battery according to claim 3. 2. A lithium-sulfur solid-state battery according to claim 1, wherein said solid electrolyte is formed of an oxide-based material. 3. The battery positive electrode sheet according to claim 2, wherein said solid electrolyte is made of an oxide material. 4. The battery negative electrode sheet according to claim 3, wherein said solid electrolyte is made of an oxide material.

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