JP6061139B2 - Method for producing positive electrode mixture for all-solid-state lithium-sulfur battery - Google Patents

Description

  The present invention relates to a positive electrode mixture and an all solid-state lithium-sulfur battery.

  Sulfur is known to have a very high theoretical capacity of about 1672 mAh / g, and lithium sulfur batteries using sulfur as a positive electrode active material have been actively studied.

  Lithium-sulfur batteries are broadly classified into liquid lithium-sulfur batteries using a liquid electrolyte as an electrolyte and all-solid-state lithium-sulfur batteries using a solid electrolyte. It has been a problem that lithium polysulfide produced by the above reaction dissolves in the electrolyte solution and adversely affects the charge / discharge capacity and life of the battery.

  On the other hand, the all-solid-state lithium-sulfur battery is suitable for maintaining the charge / discharge capacity of the battery and extending its life because there is no problem that lithium sulfide dissolves into the electrolyte solution. In addition, because it does not contain a flammable organic solvent, attention has been paid to the excellent characteristics of all-solid-state lithium-sulfur batteries, such as the possibility of ensuring safety without the risk of liquid leakage or ignition, and the need for a separator. Gathered.

In the positive electrode mixture layer of the all-solid-state lithium-sulfur battery, among the reversible reactions represented by the following formula (1), a rightward reaction during discharge and a leftward reaction during charging proceed preferentially.
S + 2Li ⁺ + 2e ⁻ ⇔ Li ₂ S (1)
However, in the all-solid-state lithium-sulfur battery, the negative electrode, the solid electrolyte layer, and the positive electrode mixture layer substantially contain no solvent, and the sulfur contained in the positive electrode mixture layer as the positive electrode active material is electrically insulating. Therefore, the electronic conductivity and lithium ion conductivity in the positive electrode mixture layer are very low. For this reason, the reactivity of the reaction shown in the above formula (1) is poor at the time of charge / discharge, and there is a problem that a sufficient charge / discharge capacity cannot be secured.

  As a method for solving this problem, it has been proposed to use a solid electrolyte having high conductivity as the solid electrolyte (ion conductive substance) contained in the positive electrode mixture (Patent Document 1). By using a solid electrolyte with high conductivity, it is believed that the resistance when lithium ions move from the negative electrode through the solid electrolyte layer to the reaction interface in the positive electrode mixture layer is reduced, and charge / discharge characteristics are improved. .

JP 2012-160415 A

  However, even when an all-solid-state lithium-sulfur battery is produced using a conventional positive electrode mixture, the charge / discharge capacity is still insufficient, and there is a problem that the excellent physical properties of sulfur cannot be fully utilized.

  The inventors of the present invention have made extensive studies on the positive electrode mixture to improve the charge / discharge capacity in the case of an all-solid-state lithium-sulfur battery. As a result, the positive electrode mixture has a high sulfur interfacial reaction improver having predetermined characteristics. As a result of using in combination with a solid electrolyte having conductivity, the resistance when sulfur, electrons and lithium ions react at the reaction interface is reduced, and the reactivity of the reaction represented by the above formula (1) is improved. The present invention was completed by obtaining new knowledge that the charge / discharge capacity of a solid-state lithium-sulfur battery can be improved.

That is, in the positive electrode mixture of the present invention, sulfur or its discharge product (A), P ₂ S ₅ , or P ₂ S ₅ is 30% or more in molar ratio with respect to the total amount of Li ₂ S and P ₂ S _5. Li ₂ S and P ₂ S _5, which are composites of sulfur interface reaction improver (B), conductive material (C), and composites of Li ₂ S and M _x S _y (where M Is at least one element selected from the group consisting of P, Si, Ge, B and Al, and x and y independently represent a stoichiometric ratio determined according to the type of M. A solid electrolyte having a composition ratio (molar ratio) of Li ₂ S: M _x S _y = 70: 30 to 85:15 and having a conductivity of 0.1 mS / cm or more. D) _(where 30% at a molar ratio of P 2 _{S 5} is the total amount of Li ₂ S and _P 2 _{S 5 Li} 2 S Includes a composite compound is excluded) with P ₂ S _5, characterized in that it is used in the positive-electrode mixture layer of the all-solid-state lithium-sulfur battery.

The positive electrode mixture of the present invention is obtained after the first mixing treatment in which the sulfur or its discharge product (A), the sulfur interface reaction improver (B), and the conductive material (C) are mixed. It is preferable that it is a thing obtained by adding the D) and performing the 2nd mixing process which mixes further.
In the positive electrode mixture of the present invention, the content of the solid electrolyte (D) is preferably 5 to 100 parts by weight with respect to 100 parts by weight of the sulfur or a discharge product (A) thereof.

Furthermore, in the positive electrode mixture of the present invention, the first mixing treatment is performed using a planetary ball mill under conditions of a revolution speed of 100 to 600 rpm and 0.1 to 15 hours, and the second mixing treatment is performed at a revolution speed of 50. It is preferably carried out using a planetary ball mill under conditions of ˜500 rpm and 0.1 to 15 hours.
Further, the solid electrolyte (D) _{is, Li 2 S: P 2 S} 5 = 75: 25~85: composite compound of Li ₂ S and _P 2 _{S 5} is 15 or _Li 2 _S,: P 2 _{S 5} : GeS ₂ = 70 to 80:20 to 10:10 is preferably a composite of Li ₂ S, P ₂ S _5, and GeS ₂ .
Furthermore, the solid electrolyte (D) may further contain a lithium salt.

Moreover, the manufacturing method of the positive electrode mixture of the present invention includes the following steps:
(1) Sulfur or discharge products _{(A), P 2 S 5} , or _P 2 _{S 5} is more than 30% by molar ratio relative to the total amount of Li ₂ S and _P 2 _{S 5} Li ₂ S and P A step of mixing a sulfur interfacial reaction improver (B) and a conductive material (C), which is a composite with ₂ S ₅ ; and (2) adding Li ₂ S and M to the mixture obtained in step (1) _x S _y complex (wherein M is at least one element selected from the group consisting of P, Si, Ge, B, and Al, and x and y are independently M Represents a stoichiometric ratio determined according to the type), and the composition ratio (molar ratio) is Li ₂ S: M _x S _y = 70: 30 to 85:15; a solid electrolyte having 1 mS / cm or more conductivity _(however, mode P 2 _{S 5} is the total amount of Li ₂ S and _P 2 _{S 5} Was added composite compound is excluded) between Li ₂ S and _P 2 _{S 5} is 30% in the ratio, further mixing step.

In the method for producing a positive electrode mixture of the present invention, the content of the solid electrolyte (D) is preferably 5 to 100 parts by weight with respect to 100 parts by weight of the sulfur or its discharge product (A).
In the method for producing a positive electrode mixture of the present invention, the mixing in the step (1) is performed using a planetary ball mill under the conditions of a revolution speed of 100 to 600 rpm and 0.1 to 15 hours. ) Is preferably performed using a planetary ball mill under conditions of a revolution speed of 50 to 500 rpm and 0.1 to 15 hours.
Furthermore, in the method for producing a positive electrode mixture of the present invention, a composite of Li ₂ S and P ₂ S _{5 in} which the solid electrolyte (D) is Li ₂ S: P ₂ S ₅ = 75: 25 to 85:15 Or Li ₂ S: P ₂ S ₅ : GeS ₂ = 70 to 80:20 to 10:10 is preferably a composite of Li ₂ S, P ₂ S ₅ and GeS ₂ .
In the method for producing a positive electrode mixture of the present invention, the solid electrolyte (D) may further contain a lithium salt.

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

In the positive electrode mixture of the present invention, P ₂ S ₅ or P ₂ S ₅ is a mixture of Li ₂ S and P ₂ S _{5 having} a molar ratio of 30% or more with respect to the total amount of Li ₂ S and P ₂ S ₅ . Since the sulfur interfacial reaction improver (B), which is a composite, is used in combination with the solid electrolyte (D) having high conductivity, when used as a positive electrode mixture layer of an all-solid-state lithium-sulfur battery, sulfur, It is possible to provide an all solid-state lithium-sulfur battery that has low resistance when electrons and lithium ions react at the reaction interface and has excellent charge / discharge characteristics.
Moreover, since the all-solid-state lithium-sulfur battery of this invention is equipped with the positive mix layer containing the positive mix of this invention, it has the characteristic which is excellent in charging / discharging characteristics.

1. Positive electrode will be described first positive-electrode mixture of the present invention.
In the positive electrode mixture of the present invention, sulfur or its discharge product (A), P ₂ S ₅ , or P ₂ S ₅ is 30% or more by molar ratio with respect to the total amount of Li ₂ S and P ₂ S _5. A composite of Li ₂ S and P ₂ S ₅ , a sulfur interface reaction improver (B), a conductive material (C), and a composite of Li ₂ S and M _x S _y (where M is Is at least one element selected from the group consisting of P, Si, Ge, B and Al, and x and y are integers that independently give a stoichiometric ratio determined according to the type of M The solid electrolyte (D) having a composition ratio (molar ratio) of Li ₂ S: M _x S _y = 70: 30 to 85:15 and having a conductivity of 0.1 mS / cm or more. _(However, Li P 2 _{S 5} is 30% in terms of the molar ratio to the total amount of Li ₂ S and _P 2 _{S 5 2} S and _{P 2} Composite compound with S ₅ is excluded) comprises, characterized in that it is used in the positive-electrode mixture layer of the all-solid-state lithium-sulfur battery.

1-1. Sulfur or its discharge product (A)
The positive electrode mixture of the present invention contains the above sulfur or its discharge product (A) as a positive electrode active material.
As the sulfur, single sulfur or the like can be used.
The sulfur discharge product is not particularly limited. For example, lithium polysulfide such as Li ₂ S ₈ , Li ₂ S ₄ , Li ₂ S ₂ , lithium sulfide (Li ₂ S), or the like is used. it can. These compounds may be used alone or in combination of two or more, or may be used in combination with single sulfur.

Although content of the said sulfur or its discharge product (A) is not specifically limited, It is preferable that it is 10 to 90 weight% with respect to a positive electrode compound material, and it is more preferable that it is 25 to 80 weight%.
When the content of the sulfur or the discharge product (A) is less than 10% by weight, a sufficient charge / discharge capacity may not be obtained. When the content exceeds 90% by weight, the sulfur interface reaction improver (B) The proportion of the conductive material (C) and the solid electrolyte (D) in the positive electrode mixture may be reduced, and the charge / discharge efficiency may be reduced.

1-2. Sulfur interfacial reaction improver (B)
The positive electrode mixture of the present invention contains a sulfur interface reaction improver (B).
In the present invention, the sulfur interface reaction improver (B) plays a role of reducing the resistance when sulfur, electrons and lithium ions react at the reaction interface in the positive electrode mixture. By blending the sulfur interface reaction improver (B) into the positive electrode mixture, the resistance when sulfur, electrons and lithium ions react at the reaction interface decreases, and the solid electrolyte (D ), The charge / discharge capacity in the case of an all-solid-state lithium-sulfur battery can be improved.

The sulfur interface reaction improver (B) is not particularly limited as long as it can reduce the resistance when sulfur, electrons and lithium ions react at the reaction interface, and specific examples thereof include P ₂ S. _5, or _P 2 _{S 5} can be mentioned composite compound such as a Li ₂ S and _P 2 _{S 5} is at least 30% by molar ratio relative to the total amount of Li ₂ S and _P 2 _{S 5.} These compounds may be used independently and may use 2 or more types together.

In the present invention, the “composite” is not simply a mixture of predetermined components, but mechanical, thermal, or chemical energy is added to a mixture of predetermined components, and the predetermined components are mixed. A chemical reaction has occurred in all or part of the above.
Further, in this specification, “composite” does not mean simply mixing predetermined components, but adding mechanical, thermal, or chemical energy to a mixture of predetermined components. A chemical reaction is caused in all or a part of a predetermined component.

The composite compound of the Li ₂ S and _P 2 _{S 5,} it is not particularly limited as long as more than 30% at a molar ratio of P 2 _{S 5} is the total amount of Li ₂ S and _P 2 _{S 5} .

As a method for obtaining a composite of Li ₂ S and P ₂ S ₅ , for example, using a planetary ball mill, a rotation speed of 150 to 500 rpm, a revolution speed of 200 to 1000 rpm (rotation and reverse rotation) is 0.5 to 10 For example, a time processing method may be used.
Here, whether Li ₂ S and P ₂ S ₅ are combined or whether Li ₂ S and P ₂ S ₅ are simply mixed can be confirmed by Raman spectroscopy. When Li ₂ S and P ₂ S ₅ are complexed, the peak near 300 cm ⁻¹ derived from P ₂ S ₅ disappears in the measurement by Raman spectroscopy, or 400 cm ⁻ Although it becomes relatively small with respect to the main peak in the vicinity of ¹ , it is possible to determine whether Li ₂ S and P ₂ S ₅ are combined using this as an index.

The content of the sulfur interface reaction improver (B) in the positive electrode mixture is not particularly limited, but is 10 to 200 parts by weight with respect to 100 parts by weight of sulfur in the positive electrode mixture or its discharge product (A). It is preferably 20 to 100 parts by weight.
When the content is less than 10 parts by weight, the resistance when sulfur, electrons and lithium ions react at the reaction interface cannot be sufficiently reduced, and the charge / discharge capacity may be insufficient, If it exceeds 200 parts by weight, the proportion of sulfur or its discharge product (A), conductive material (C) and solid electrolyte (D) in the positive electrode mixture decreases, and the charge / discharge capacity per positive electrode mixture decreases. Sometimes.

1-3. Conductive material (C)
The positive electrode mixture of the present invention contains a conductive material (C) as an electron conductor.
Although it does not specifically limit as said electrically conductive material (C), For example, acetylene black, activated carbon, carbon black (henceforth Ketjen black (trademark)) which has a hollow shell structure, furnace black, a carbon nanotube, graphene etc. are mentioned. It is done.
Among these, acetylene black, ketjen black, and activated carbon are preferable because they are excellent in conductivity and have a large BET specific surface area.

  The carbon black having a hollow shell structure is a kind of conductive carbon black and has a hollow shell structure with a porosity of about 60 to 80%. Here, the “hollow shell structure” refers to a structure in which graphite crystals are thinly gathered to form an outer shell in the form of particles and have voids inside the outer shell. Examples of the carbon black having the hollow shell structure include ketjen black (manufactured by Lion Corporation).

Although the BET specific surface area of the said electrically conductive material (C) is not specifically limited, It is preferable that it is 10 m < ² > / g or more, and it is more preferable that it is 100 m < ² > / g or more.
When the BET specific surface area is less than 10 m ² / g, the electron conductivity in the positive electrode mixture becomes insufficient, and the charge / discharge efficiency may be lowered.

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

Although content of the said electrically conductive material (C) is not specifically limited, It is preferable that it is 5-200 weight part with respect to 100 weight part of sulfur or its discharge product (A) in positive electrode compound material, 10-100 More preferred are parts by weight.
If the content of the conductive material (C) is less than 5 parts by weight, the amount of electrons that can move to the positive electrode may decrease, and a sufficient discharge capacity may not be obtained. The proportion of the active substance (A) and sulfur or its discharge product (B) in the positive electrode mixture is reduced, and the charge / discharge efficiency may be reduced.

1-4. Solid electrolyte (D)
The positive electrode composite of the present invention is a composite of Li ₂ S and M _x S _y (where M is at least one element selected from the group consisting of P, Si, Ge, B, and Al). X and y each independently represents an integer giving a stoichiometric ratio determined according to the type of M), and the composition ratio (molar ratio) is Li ₂ S: M _x S _y = 70:30 to 85:15, solid electrolyte (D) having a conductivity of 0.1 mS / cm or more (provided that P ₂ S ₅ is a molar ratio with respect to the total amount of Li ₂ S and P ₂ S ₅ (Except for a composite of Li ₂ S and P ₂ S ₅ , which is 30%) as a solid electrolyte. In the positive electrode mixture of the present invention, by using the solid electrolyte (D) in combination with the sulfur interface reaction improver, the charge / discharge capacity in the case of an all solid lithium-sulfur battery can be further improved.
Moreover, the said solid electrolyte (D) is used also for preparation of the solid electrolyte layer mentioned later.

The solid electrolyte (D) is not particularly limited as long as the electrical conductivity is 0.1 mS / cm or more, but a composite of Li ₂ S and M _x S _y (where M is P, It is at least one element selected from the group consisting of Si, Ge, B and Al, and x and y independently represent an integer giving a stoichiometric ratio determined according to the type of M And the composition ratio (molar ratio) is Li ₂ S: M _x S _y = 70: 30 to 85:15 (provided that P ₂ S ₅ is the total amount of Li ₂ S and P ₂ S ₅ ) (Excluding a composite of Li ₂ S and P ₂ S ₅ having a molar ratio of 30% to the other) can be preferably used. In the positive electrode composite of the present invention, Li ₂ S: P ₂ S ₅ = 75: 25 to 85 is used as the solid electrolyte (D) from the viewpoint of further improving the charge / discharge capacity in the case of an all solid lithium-sulfur battery. : composite compound of Li ₂ S and _P 2 _{S 5} is 15, or _{Li 2 S: P 2 S 5} : GeS 2 = 70~80: 20~10: 10~0 a is Li ₂ S and _P 2 S A composite of ₅ and GeS ₂ is more preferably used.
These solid electrolytes (D) may be used independently and may use 2 or more types together.

As a method of obtaining a composite of Li ₂ S and M _x S _y , for example, using a planetary ball mill, a rotation speed of 150 to 500 rpm, a revolution speed of 200 to 1000 rpm (rotation and reverse rotation) is 0.5 to 10 For example, a time processing method may be used.
Here, it can be confirmed by Raman spectroscopy whether Li ₂ S and M _x S _y are complexed or Li ₂ S and M _x S _y are simply mixed. For example, when Li ₂ S and P ₂ S ₅ are complexed, the peak near 300 cm ⁻¹ derived from P ₂ S ₅ disappears in the measurement by Raman spectroscopy, as compared with the case of simply mixing, or Although it becomes relatively small with respect to the main peak in the vicinity of 400 cm ^−1, it can be determined whether or not Li ₂ S and P ₂ S ₅ are combined using this as an index.

The solid electrolyte (D) may further contain a lithium salt or lithium nitride.
Examples of the lithium salt is not particularly limited, examples thereof _{include Li 3 PO 4, Li 4 SiO} 4, Li 2 O, LiI, Li 3 N, the LiBH ₄ or the like.
Although not particularly restricted but includes lithium nitride, for example, Li 3 _N and the like.
When the lithium electrolyte or lithium nitride is included in the solid electrolyte (D), the electrical conductivity of the solid electrolyte (D) can be further increased, and the charge / discharge capacity in the case of an all-solid-state lithium-sulfur battery can be further improved. Because there is.

  Although content of the said solid electrolyte (D) is not specifically limited, It is preferable that it is 5-100 weight part with respect to 100 weight part of sulfur in the positive electrode compound material or its discharge product (A), More preferably, it is 80 parts by weight.

1-5. Components that can be optionally added The positive electrode mixture of the present invention may contain optional components such as a binder and a solvent, if necessary.

1-5-1. Binder The binder that can be used in the present invention is not particularly limited, and examples thereof include thermoplastic resins and thermosetting resins. Examples thereof include polyethylene, polypropylene, polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF). ), Styrene butadiene rubber, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride- Hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer (ETFE resin), polychlorotrifluoroethylene (PCTFE), vinyl Vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride -Perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer and the like. These binders may be used alone or in combination of two or more.
Although content of the said binder is not specifically limited, It is preferable to contain 0.01 to 10weight% in the said positive electrode compound material.

1-5-2. Solvent The solvent that can be used in the present invention is not particularly limited, but examples thereof include amine solvents such as N, N-dimethylaminopropylamine and diethylenetriamine, ether solvents such as tetrahydrofuran, ketone solvents such as methyl ethyl ketone, and methyl acetate. And ester solvents such as dimethylacetamide and 1-methyl-2-pyrrolidone, and hydrocarbon solvents such as toluene, xylene, n-hexane and cyclohexane. These solvents may be used alone or in combination of two or more.
Although content of the said solvent is not specifically limited, It is preferable that 10 to 99 weight% is contained in the said positive electrode compound material.
By using the positive electrode mixture containing the solvent, the production of the positive electrode mixture layer can be facilitated. The solvent is removed by drying when the positive electrode mixture layer is produced.

The positive electrode mixture of the present invention comprises the above sulfur or its discharge product (A), the above sulfur interface reaction improver (B), the above conductive material (C) and the above solid electrolyte (D), and a binder and a solvent as necessary. The sulfur or its discharge product (A), the sulfur interfacial reaction improver (B), the conductive material (C) and the solid electrolyte ( For the four components of D), after the first mixing treatment in which the sulfur or its discharge product (A), the sulfur interface reaction improver (B), and the conductive material (C) are mixed, the solid electrolyte (D It is preferable that it is obtained by performing the 2nd mixing process which adds and mixes.
The reason for this is that by mixing in two stages, the sulfur interface reaction improver (B) is arranged in the vicinity of the sulfur or its discharge product (A) in the first mixing process, and further in the second mixing process. In addition, the solid electrolyte (D) having a high conductivity is disposed on the surface of the mixture obtained by the first mixing treatment and the periphery thereof, thereby further improving the charge / discharge capacity in the case of an all-solid-state lithium-sulfur battery. Because it can.
The optional component may be added during or after the first mixing process, or may be added during or after the second mixing process.

The means for mixing these is not particularly limited, but for example, planetary ball mill (Fritsch), hybridization system (Nara Machinery Co., Ltd.), cosmos (Kawasaki Heavy Industries), mechanofusion system (Hosokawa Micron) , Mechano Mill (Okada Seiko Co., Ltd.), Theta Composer (Tokusu Kosakusho Co., Ltd.), Nano Sonic Mill (Inoue Seisakusho Co., Ltd.), Kneader (Inoue Seisakusho Co., Ltd.), Super Mass Colloid (Masako Sangyo Co., Ltd.), Nanomec Reactor (Techno Eye Co., Ltd.), Cornell Despa (Asada Iron Works Co., Ltd.), Planetary Mixer (Asada Iron Works Co., Ltd.) and the like can be used.
When mixing using a planetary ball mill, the first mixing process is preferably performed under conditions of a revolution speed of 100 to 600 rpm and 0.1 to 15 hours, and the second mixing process is performed at a revolution speed of 50. It is preferable to carry out under the conditions of ~ 500 rpm and 0.1 to 15 hours.
The reason for this is that, in the first mixing process, when only weak energy is applied compared to the above-described conditions, the sulfur or its discharge product (A) and the sulfur interfacial reaction improver (B) are used. In this case, the reactivity between these components may be reduced when an all-solid-state lithium-sulfur battery is used. On the contrary, stronger energy is applied than in the above conditions. This is because the sulfur or its discharge product (A) and the sulfur interface reaction improver (B) may react unintentionally during the mixing process. Also, in the second mixing treatment, in the condition where only weak energy is applied compared to the case of the above condition, the sulfur or its discharge product (A) and the sulfur interface reaction improver (B), and the solid electrolyte As a result of insufficient contact of lithium ions with insufficient contact with (D), the charge / discharge capacity in the case of an all-solid-state lithium-sulfur battery may be reduced. In the case of a condition in which stronger energy is applied than in the case of the above condition, as a result of equalization of the respective compositions of the sulfur interface reaction improver (B) and the solid electrolyte (D) and a decrease in conductivity, an all-solid-state lithium-sulfur battery This is because it may adversely affect the characteristics.

2. Method for Producing Positive Electrode Mixture The positive electrode composite of the present invention comprises the sulfur or its discharge product (A), the sulfur interfacial reaction improver (B), the conductive material (C) and the solid electrolyte (D), necessary. Depending on the case, it can be obtained by mixing optional components such as a binder and a solvent.

The method for producing a positive electrode mixture of the present invention preferably includes the following steps:
(1) Sulfur or discharge products _{(A), P 2 S 5} , or _P 2 _{S 5} is more than 30% by molar ratio relative to the total amount of Li ₂ S and _P 2 _{S 5} Li ₂ S and P A step of mixing a sulfur interfacial reaction improver (B) and a conductive material (C), which is a composite with ₂ S ₅ ; and (2) adding Li ₂ S and M to the mixture obtained in step (1) _x S _y complex (wherein M is at least one element selected from the group consisting of P, Si, Ge, B, and Al, and x and y are independently M Represents a stoichiometric ratio determined according to the type), and the composition ratio (molar ratio) is Li ₂ S: M _x S _y = 70: 30 to 85:15; a solid electrolyte having 1 mS / cm or more conductivity _(however, mode P 2 _{S 5} is the total amount of Li ₂ S and _P 2 _{S 5} Was added composite compound is excluded) between Li ₂ S and _P 2 _{S 5} is 30% in the ratio, further mixing step.
The reason for this is that by mixing in two stages, the sulfur interface reaction improver (B) is arranged in the vicinity of the sulfur or its discharge product (A) in the first mixing process, and further in the second mixing process. In addition, the solid electrolyte (D) having a high conductivity is disposed on the surface of the mixture obtained by the first mixing treatment and the periphery thereof, thereby further improving the charge / discharge capacity in the case of an all-solid-state lithium-sulfur battery. Because it can.
The optional component may be added during or after the step (1), or may be added during or after the step (2).

  The means for mixing each component in the above step (1) and step (2) is not particularly limited. For example, planetary ball mill (manufactured by Fritsch), hybridization system (manufactured by Nara Machinery Co., Ltd.), cosmos (Kawasaki) Heavy Industries Co., Ltd.), Mechano-Fusion System (Hosokawa Micron Corp.), Mechano Mill (Okada Seiko Co., Ltd.), Theta Composer (Tokusu Kosakusho Co., Ltd.), Nano Sonic Mill (Inoue Seisakusho Co., Ltd.), Kneader (Inoue Seisakusho Co., Ltd.), Examples of the mixing method include a super mass collider (manufactured by Masuko Sangyo Co., Ltd.), a nanomec reactor (manufactured by Techno Eye Co., Ltd.), Cornell Despa (manufactured by Asada Iron Works Co., Ltd.), and a planetary mixer (manufactured by Asada Iron Works Co., Ltd.).

When mixing using a planetary ball mill, the first mixing process is preferably performed under conditions of a revolution speed of 50 to 600 rpm and 0.1 to 15 hours, and the second mixing process is performed at a revolution speed of 50. It is preferable to carry out under the conditions of ~ 600 rpm and 0.1 to 15 hours.
This is because, in the mixing of the step (1), in the case where only weak energy is added compared to the case of the above-mentioned condition, the sulfur or its discharge product (A) and the sulfur interfacial reaction improver (B). Insufficient contact can be ensured, and the reactivity between these components tends to decrease when an all-solid-state lithium-sulfur battery is used. In the case where the energy is applied, the sulfur or the discharge product (A) and the sulfur interface reaction improver (B) may react unintentionally during the mixing process. Also, in the mixing in the step (2), in the case where only weak energy is applied compared to the above-described conditions, the sulfur or its discharge product (A) and the sulfur interface reaction improver (B) As a result of insufficient contact between the solid electrolyte (D) and insufficient movement of lithium ions, the charge / discharge capacity of an all-solid-state lithium-sulfur battery may be reduced. In addition, in the case of a condition where stronger energy is applied than in the case of the above condition, the respective compositions of the sulfur interface reaction improver (B) and the solid electrolyte (D) are equalized and the conductivity is lowered. This is because there may be an adverse effect on the characteristics of the lithium-sulfur battery.

In the production of the positive electrode mixture, heat treatment may be performed after the first mixing process and / or the second mixing process.
The reason for this is that the resistance at the reaction interface can be further reduced as a result of the heat treatment strengthening the contact interface of each component contained in the positive electrode mixture.
Although the said heat processing is not specifically limited, For example, you may perform on 80-250 degreeC, preferably 100-200 degreeC conditions for 1 second-10 hours conditions, such as argon, nitrogen, air.
The heat treatment may be performed using a conventionally known heating means. Specifically, for example, a constant temperature dryer, an air dryer, a vacuum dryer, an infrared dryer, or the like may be used.

3. Next, the all solid-state lithium-sulfur battery of the present invention will be described.
The all-solid-state lithium-sulfur battery of the present invention is an all-solid-state lithium-sulfur battery including a positive electrode mixture layer including the positive electrode mixture of the present invention, a solid electrolyte layer, a negative electrode, and a current collector.

In the present specification, the “all solid type” means a polymer solid electrolyte and / or an inorganic solid electrolyte as an electrolyte, and contains substantially no solvent in the negative electrode, the solid electrolyte layer, and the positive electrode mixture layer. Say things.
In the present specification, “substantially no solvent” means that a trace amount of the solvent may remain.
Hereinafter, each of the current collector (negative electrode current collector, positive electrode current collector), negative electrode, solid electrolyte layer, and positive electrode mixture layer will be described in order.

3-1. Current collector The current collector is not particularly limited. For example, Al, Cu, Ni, stainless steel, or the like can be used.
As the negative electrode current collector, Cu is preferably used because it is difficult to make an alloy with lithium and it can be easily processed into a thin film. As the positive electrode current collector, Al is preferably used because it is easy to process into a thin film and is inexpensive.

3-2. Examples of the negative electrode The negative electrode, as long as it comprises a material capable of absorbing and releasing lithium ions as a negative electrode active material, is not particularly limited. Here, examples of the material that occludes and releases lithium ions include metallic lithium, lithium alloy, metal oxide, metal sulfide, and a carbonaceous substance that occludes and releases lithium ions.
Examples of the lithium alloy include alloys of lithium, aluminum, silicon, tin, magnesium, indium, calcium, and the like.
Examples of the metal oxide include tin oxide, silicon oxide, lithium titanium oxide, niobium oxide, and tungsten oxide.
Examples of the metal sulfide include tin sulfide and titanium sulfide.
Examples of the carbonaceous material that absorbs and releases lithium ions include graphite, coke, mesophase pitch-based carbon fiber, spherical carbon, and resin-fired carbon.

The method of obtaining the negative electrode is not particularly limited, but a method of pressing the material that absorbs and releases lithium ions, and a negative electrode precursor dispersion containing the material that absorbs and releases lithium ions and a solvent are used as a negative electrode current collector. Examples thereof include a method of pressing after coating and drying.
As the solvent contained in the negative electrode precursor dispersion, the same solvents as those used for the positive electrode mixture can be used.
The solvent is used to assist the application of the negative electrode precursor dispersion and is removed by drying after the application.

3-3. Solid electrolyte layer Examples of the solid electrolyte layer include those made of a polymer solid electrolyte and / or an inorganic solid electrolyte.
The solid electrolyte layer made of the inorganic solid electrolyte can be obtained by, for example, a method of pressure-molding the solid electrolyte (D), a method of dispersing and solidifying the solid electrolyte (D) in a solvent, and the like. .
The method for pressure forming the solid electrolyte (D) is not particularly limited. For example, a method of pressing the solid electrolyte (D) between a negative electrode current collector and a positive electrode current collector, The method etc. which press with a jig | tool are mentioned.
When the solid electrolyte layer is obtained by a method in which the solid electrolyte (D) is dispersed in a solvent and then applied and dried, the dried solid electrolyte layer may be pressed by the same method as described above.
As the solvent for dispersing the solid electrolyte (D), the same solvents as those used for the positive electrode mixture can be used.
When a solid electrolyte layer is obtained by these methods, heat treatment may be performed at an arbitrary timing for the purpose of reducing the interface resistance of the solid electrolyte layer and improving the denseness.
Examples of the solid electrolyte layer made of the polymer solid electrolyte include polyethylene oxide polymers containing lithium salts such as lithium perchlorate and lithium bistrifluoromethanesulfonylamide.

3-4. Positive electrode mixture layer The positive electrode mixture layer can be obtained by, for example, a method of supporting the positive electrode mixture on a positive electrode current collector, a method of pressure forming the positive electrode mixture, or the like.
The method of supporting the positive electrode mixture on the positive electrode current collector is not particularly limited. For example, a method of pressure-forming the positive electrode mixture, a positive electrode mixture paste using an organic solvent or the like is used as the positive electrode current collector. For example, there may be mentioned a method of fixing by applying, drying and pressing.
The method for pressure forming the positive electrode mixture is not particularly limited. For example, a method of pressing the positive electrode mixture between the solid electrolyte layer and the positive electrode current collector and pressing with a jig of the pressure molding machine And the like.
The method for applying the positive electrode mixture to the positive electrode current collector is not particularly limited, and examples thereof include a slit die coating method, a screen coating method, a curtain coating method, a knife coating method, a gravure coating method, and an electrostatic spray method. It is done.
When the positive electrode mixture layer is obtained by these methods, heat treatment may be performed at an arbitrary timing for the purpose of reducing the interface resistance of the positive electrode mixture layer and improving the denseness.

The all solid-state lithium-sulfur battery may have a separator, in addition to the above-described negative electrode current collector, negative electrode, solid electrolyte layer, positive electrode mixture layer, and positive electrode current collector.
The shape of the all-solid-state lithium-sulfur battery is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, and a rectangular type.

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

5. Application of all-solid-state lithium-sulfur battery The application of the all-solid-state lithium-sulfur battery is not particularly limited. For example, it can be suitably used for electric products that require high energy density, such as hybrid cars and electric cars. .

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

1. Measurement Method In Examples and Comparative Examples described later, the conductivity of the solid electrolyte was measured by the following method.
1-1. Measuring method of conductivity Cylindrical jig made of SUS304 (10 mmφ, height 10 mm) from the lower side of a cylindrical tube jig made of polycarbonate (inner diameter 10 mmΦ, outer diameter 23 mmΦ, height 20 mm) (hereinafter also referred to as current collector 2) ) And 100 mg of solid electrolyte from the upper side of the cylindrical tube jig made of polycarbonate. Further, a cylindrical jig made of SUS304 (10 mmΦ, height 15 mm) (hereinafter also referred to as current collector 1) is made of a polycarbonate cylinder. A sample for conductivity measurement was produced by forming a solid electrolyte layer having a diameter of 10 mmΦ and a thickness of about 0.8 mm by inserting from the upper side of the tube jig, sandwiching the solid electrolyte, and pressing at a pressure of 200 MPa for 3 minutes. .
The resistance value of this sample was measured by AC impedance measurement using a cell test system 1400 manufactured by Solartron, and the conductivity was calculated from the thickness and diameter of the solid electrolyte layer (applied voltage 50 mV, measurement frequency 1 to 1,000,000 Hz). ).

2. Production of positive electrode mixture (Example 1)
Li ₂ S (manufactured by Furuuchi Chemical Co., Ltd.) and P ₂ S ₅ (manufactured by Aldrich) were weighed to a molar ratio of 65:35 and mixed in a mortar with a planetary ball mill at a rotational speed of 250 rpm. It is compounded by treating at a speed of 500 rpm (autorotation and reverse rotation) for 10 hours to obtain a compound (sulfur interface reaction improver) having a composition ratio (molar ratio) of Li ₂ S: P ₂ S ₅ = 65: 35. It was.
Using this sulfur interfacial reaction improver, sulfur (positive electrode active material; manufactured by Aldrich), ketjen black (conductive material; specific surface area 1200 m ² / g, manufactured by Lion Corporation, EC600JD), the composition ratio (weight ratio) ) Was measured so that the sulfur interfacial reaction improver 120 mg, the positive electrode active material 120 mg, and the conductive material 30 mg, and planetary ball mill (Premium line P-7 manufactured by Filsch, revolution radius 0.07 m, rotation radius) The precursor of the positive electrode mixture was obtained by compounding at about 235 rpm in a 45 ml pot at a revolution speed of 370 rpm together with about 40 g of 5 mm zirconia balls at 0.0235 m, the ratio of rotation to revolution = -2).

Next, Li ₂ S (manufactured by Furuuchi Chemical Co., Ltd.) and P ₂ S ₅ (manufactured by Aldrich) were weighed so as to have a molar ratio of 80:20, and mixed in a mortar with a planetary ball mill. A composite having a composition ratio (molar ratio) of Li ₂ S: P ₂ S ₅ = 80: 20 was obtained by treating at 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation) for 10 hours (solid electrolyte; conductive (Rate 0.48 mS / cm).
Using the obtained positive electrode mixture precursor and a solid electrolyte, 180 mg of the precursor and 20 mg of the solid electrolyte were weighed so that the composition ratio (weight ratio) was 90:10, and a planetary ball mill (premium manufactured by Filsch) was measured. By mixing for 30 minutes at a revolution speed of 250 rpm in a 45 ml pot with a line P-7, a revolution radius of 0.07 m, a revolution radius of 0.0235 m, a ratio of revolution to revolution = -2) and about 40 g of 5 mm zirconia balls. A positive electrode mixture for an all-solid-state lithium-sulfur battery was obtained.

(Example 2)
Using the sulfur interface reaction improver obtained in Example 1, sulfur (positive electrode active material; manufactured by Aldrich), and acetylene black (conductive material; specific surface area 70 m ² / g, manufactured by Aldrich), the composition ratio ( 90 mg of sulfur interfacial reaction improver, positive electrode active material 75 mg, and conductive material 75 mg were weighed so that the weight ratio was 30:25:25, and planetary ball mill (Premium line P-7 manufactured by Filsch, revolution radius 0.07 m, A precursor of a positive electrode mixture was obtained by compounding at a revolution speed of 370 rpm in a 45 ml pot together with about 40 g of 5 mm zirconia balls at a revolution radius of 0.0235 m and a ratio of rotation to revolution = -2).

  Using the obtained precursor and the solid electrolyte obtained in Example 1, 160 mg of the precursor and 40 mg of the solid electrolyte were weighed so that the composition ratio (weight ratio) was 80:20, and a planetary ball mill ( Premium line P-7 manufactured by Frillsch, revolution radius 0.07m, revolution radius 0.0235m, rotation to revolution ratio = -2) and about 40g of 5mm zirconia balls in 45ml pot at revolution speed 250rpm for 30 minutes By mixing, a positive electrode mixture for an all-solid-state lithium-sulfur battery was obtained.

Example 3
The same operation as in Example 2 except that Li ₂ S and P ₂ S ₅ were combined at a composition ratio (molar ratio) of 75:25 (conductivity: 0.30 mS / cm) as the solid electrolyte. Thus, a positive electrode mixture was obtained.

(Comparative Example 1)
Using a solid electrolyte (prepared in Example 1), sulfur (positive electrode active material; manufactured by Aldrich), and ketjen black (conductive material; specific surface area 1200 m ² / g, manufactured by Lion Corporation, EC600JD), the composition ratio A solid electrolyte 100 mg, a positive electrode active material 80 mg, and a conductive material 20 mg were weighed so that (weight ratio) was 50:40:10, and a planetary ball mill (Premium line P-7 manufactured by Filsch, revolution radius 0.07 m, rotation radius) A mixture of positive electrodes for an all-solid-state lithium-sulfur battery is prepared by mixing for 2 hours at a revolution speed of 370 rpm in a 45 ml pot together with about 40 g of a 5 mm zirconia ball at 0.0235 m, the ratio of rotation to revolution = -2). Obtained.

(Comparative Example 2)
Using a solid electrolyte (produced in Example 1), sulfur (positive electrode active material; manufactured by Aldrich), and acetylene black (conductive material; specific surface area 70 m ² / g, manufactured by Aldrich), the composition ratio (weight ratio) A positive electrode mixture was obtained in the same manner as in Comparative Example 1 except that 100 mg of the solid electrolyte, 50 mg of the positive electrode active material, and 50 mg of the conductive material were weighed so as to be 50:25:25.

Example 4
Li ₂ S (manufactured by Furuuchi Chemical Co., Ltd.) and P ₂ S ₅ (manufactured by Aldrich) were weighed to a molar ratio of 50:50, and mixed in a mortar with a planetary ball mill at a rotational speed of 250 rpm. Compounding by treating for 10 hours at a speed of 500 rpm (autorotation and reverse rotation), a composite (sulfur interface reaction improver) having a composition ratio (molar ratio) of Li ₂ S: P ₂ S ₅ = 50: 50 is obtained. It was.
Using this sulfur interfacial reaction improver, sulfur (positive electrode active material; manufactured by Aldrich), ketjen black (conductive material; specific surface area 1200 m ² / g, manufactured by Lion Corporation, EC600JD), the composition ratio (weight ratio) ) 72 mg of sulfur interfacial reaction improver, 120 mg of positive electrode active material, and 24 mg of conductive material were weighed so that the ratio would be 30:50:10. Planetary ball mill (Premium line P-7 manufactured by Filsch, revolution radius 0.07 m, rotation radius) The precursor of the positive electrode mixture was obtained by compounding at about 235 rpm in a 45 ml pot at a revolution speed of 370 rpm together with about 40 g of 5 mm zirconia balls at 0.0235 m, the ratio of rotation to revolution = -2).

  Using the obtained positive electrode mixture precursor and a solid electrolyte (produced in Example 1), 180 mg of the precursor and 20 mg of the solid electrolyte were weighed so that the composition ratio (weight ratio) was 90:10. , Revolving speed in a 45 ml pot with a planetary ball mill (Premium line P-7 manufactured by Filsch, revolution radius 0.07 m, rotation radius 0.0235 m, rotation to revolution ratio = -2) and about 40 g of 5 mm zirconia balls By mixing at 300 rpm for 30 minutes, a positive electrode mixture for an all solid-state lithium-sulfur battery was obtained.

(Example 5)
The positive electrode was operated in the same manner as in Example 4 except that Li ₂ S (manufactured by Furuuchi Chemical Co., Ltd.) and P ₂ S ₅ (manufactured by Aldrich) were adjusted as a sulfur interface reaction improver to a molar ratio of 40:60. A mixture was obtained.

(Example 6)
The positive electrode was operated in the same manner as in Example 4 except that Li ₂ S (manufactured by Furuuchi Chemical Co., Ltd.) and P ₂ S ₅ (manufactured by Aldrich) were adjusted to a molar ratio of 30:70 as the sulfur interface reaction improver. A mixture was obtained.

(Example 7)
The positive electrode was operated in the same manner as in Example 4 except that Li ₂ S (manufactured by Furuuchi Chemical Co., Ltd.) and P ₂ S ₅ (manufactured by Aldrich) were adjusted to a molar ratio of 20:80 as a sulfur interface reaction improver. A mixture was obtained.

(Example 8)
The positive electrode was operated in the same manner as in Example 4 except that Li ₂ S (manufactured by Furuuchi Chemical Co., Ltd.) and P ₂ S ₅ (manufactured by Aldrich Co.) were adjusted as the sulfur interface reaction improver to a molar ratio of 10:90. A mixture was obtained.

Example 9
A positive electrode mixture was obtained in the same manner as in Example 4, except that P ₂ S ₅ (manufactured by Aldrich) was used as the sulfur interface reaction improver.

(Example 10)
A planetary ball mill prepared by weighing Li ₂ S (manufactured by Furuuchi Chemical Co., Ltd.), P ₂ S ₅ (manufactured by Aldrich) and GeS ₂ as a solid electrolyte so as to have a molar ratio of 5: 1: 1 and mixing them in a mortar. Then, Li ₂ S: P ₂ S ₅ : GeS ₂ = 5 by treating at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation) for 10 hours and further heating at 510 ° C. for 8 hours in an argon atmosphere. A composite having a composition ratio (molar ratio) of 1: 1 was obtained (solid electrolyte; conductivity 5.8 mS / cm). A positive electrode mixture was obtained in the same manner as in Example 9, except that this solid electrolyte was used.

(Comparative Example 3)
Using a solid electrolyte (produced in Example 1), sulfur (positive electrode active material; manufactured by Aldrich), and ketjen black (conductive material; specific surface area 1200 m ² / g, manufactured by Lion Corporation, EC600JD), the composition ratio A positive electrode mixture was obtained in the same manner as in Comparative Example 1 except that 80 mg of the solid electrolyte, 100 mg of the positive electrode active material, and 20 mg of the conductive material were weighed so that the (weight ratio) was 40:50:10.

3. Production of an all-solid-state lithium-sulfur battery A cylindrical jig made of SUS304 (10 mmΦ, height 10 mm) is used as a negative electrode current collector from the lower side of a polycarbonate cylindrical tube jig (inner diameter 10 mmΦ, outer diameter 23 mmΦ, height 20 mm). 70 mg of a solid electrolyte (composite of 80Li ₂ S-20P ₂ S ₅ baked at 240 ° C. for 1 hour) is put from the upper side of the cylindrical tube jig made of polycarbonate, and a cylindrical treatment made of SUS304 is used as a positive electrode current collector. A solid electrolyte layer having a diameter of 10 mmΦ and a thickness of about 0.6 mm is formed by inserting a tool (10 mmΦ, height 15 mm) from the upper side of a cylindrical tube jig made of polycarbonate, sandwiching the solid electrolyte, and pressing at a pressure of 200 MPa for 3 minutes. Formed.

  Next, the cylindrical jig (positive electrode current collector) made of SUS304 inserted from the upper side was once extracted, and the positive electrodes produced in Examples 1 to 10 and Comparative Examples 1 to 3 on the solid electrolyte layer in the polycarbonate cylindrical tube. Insert the compound material to a sulfur weight of 3.75 mg, insert a SUS304 cylindrical jig (positive electrode current collector) from the upper side again, and press it at a pressure of 200 MPa for 3 minutes. A 0.1 mm positive electrode mixture layer was formed.

Next, the cylindrical jig made of SUS304 (negative electrode current collector) inserted from the lower side was extracted, and a lithium sheet (manufactured by Furuuchi Chemical Co., Ltd.) having a thickness of 0.25 mm as a negative electrode was punched into a diameter of 8 mmΦ with a punch. A 0.3 mm thick indium sheet (manufactured by Furuuchi Chemical Co., Ltd.) is punched with a punch and punched to a diameter of 9 mm and is inserted from the lower side of the polycarbonate cylindrical tube jig, and again from the lower side, the cylindrical jig made of SUS304 (Negative electrode current collector) was inserted and pressed at 80 MPa for 3 minutes to form a lithium-indium alloy negative electrode.
As described above, an all-solid-state lithium-sulfur battery in which the negative electrode current collector, the lithium-indium alloy negative electrode, the solid electrolyte layer, the positive electrode mixture layer, and the positive electrode current collector were stacked in this order from the bottom was produced.

4). Evaluation of all solid-state lithium-sulfur batteries
(Charge / discharge test)
Using the produced all solid-state lithium-sulfur battery, charging / discharging was repeated at a current density of 0.64 mA / cm ² using a charging / discharging device (ACD-M01A, manufactured by Asuka Electronics Co., Ltd.). Table 1 shows the capacity per positive electrode composite at the 10th cycle.

5. Results and Discussion From the above experimental examples and comparative examples, charge / discharge is achieved by using a positive electrode mixture in which the sulfur interface reaction improver (B) and the solid electrolyte (D) are combined in the positive electrode mixture layer of an all-solid-state lithium-sulfur battery. It became clear that an all-solid-state lithium-sulfur battery excellent in capacity can be obtained.

Claims (5)

A method for producing a positive electrode mixture, which is used for a positive electrode mixture layer of an all-solid-state lithium-sulfur battery, including the following steps:
(1) Sulfur or discharge products _{(A), P 2 S 5} , or _P 2 _{S 5} is more than 30% by molar ratio relative to the total amount of Li ₂ S and _P 2 _{S 5} Li ₂ S and P ₂ is a composite compound with S _5, sulfur interfacial reaction improver (B), and a conductive material of step (C) conjugating; the composite material obtained in well (2) step (1), Li ₂ Compound of S and M _x S _y (where M is at least one element selected from the group consisting of P, Si, Ge, B and Al, and x and y are independently Represents a stoichiometric ratio determined according to the type of M, and the composition ratio (molar ratio) is Li ₂ S: M _x S _y = 70: 30 to 85:15 , Solid electrolyte (D) having a conductivity of 0.1 mS / cm or more (provided that P ₂ S ₅ is the total amount of Li ₂ S and P ₂ S ₅ And a mixture of Li ₂ S and P ₂ S ₅ having a molar ratio of 30% with respect to the mixture. The content of the solid electrolyte (D) is, relative to the sulfur or discharge products thereof (A) 100 parts by weight of a 5 to 100 parts by weight The process of claim 1. Composite is revolving speed 100~600rpm of the step (1) is performed using a planetary ball mill under the conditions of 0.1 to 15 hours, mixing of the step (2) is revolving speed 50 to 500 rpm, 0. The manufacturing method of Claim 1 or 2 performed using a planetary ball mill on the conditions for 1 to 15 hours. The solid electrolyte (D) is a composite of Li ₂ S and P ₂ S _{5 in} which Li ₂ S: P ₂ S ₅ = 75: 25 to 85:15, or Li ₂ S: P ₂ S ₅ : GeS ₂ = 70-80: 20 to 10: 10 to 0 is a complex compound of Li ₂ S and _P 2 _{S 5} and GeS ₂ is a method according to any one of claims 1 to 3. The solid electrolyte (D) is _{LiPO 4, LiSiO 4, Li 2} O, LiI, further comprising at least one lithium salt selected from the group consisting of LiBH ₄ and Li ₃ N, either of claims 1 to 4, 1 The production method according to item.