Binder composition for all-solid-state secondary battery, slurry composition for all-solid-state secondary battery, solid electrolyte layer-containing, and all-solid-state secondary battery

Abstract

The present invention aims to provide a binder composition which can produce a slurry composition having excellent dispersibility and can form a solid electrolyte-containing layer that can allow a full solid secondary battery to exhibit excellent cycle characteristics. The binder composition of the present invention contains a polymer and an aromatic halide. The above-mentioned polymer contains a nitrile group-containing monomer unit in a proportion of 10 mass% or more and 35 mass% or less and a (meth)acrylate monomer unit in a proportion of 15 mass% or more and 40 mass% or less. The above-mentioned aromatic halide has a structure in which 2 or more and 4 or less halogen atoms are directly bonded to an aromatic ring, and the content of the above-mentioned aromatic halide in the binder composition is 5 mass ppm or more and 3000 mass ppm or less relative to the content of the above-mentioned polymer.

Description

TECHNICAL FIELD

[0001] The present application relates to a binder composition for a full solid-state secondary battery, a slurry composition for a full solid-state secondary battery, a solid-state electrolyte layer-containing layer, and a full solid-state secondary battery. BACKGROUND

[0002] In recent years, secondary batteries such as lithium ion secondary batteries are not only used in mobile terminals such as mobile information terminals and mobile electronic devices, but also in various applications such as household small power storage devices, motorcycles, electric vehicles, and hybrid vehicles. Furthermore, as the applications expand, there is a demand for further improvement in the safety of secondary batteries.

[0003] Therefore, as a secondary battery with high safety, a full solid-state secondary battery using a solid-state electrolyte instead of an organic solvent electrolyte with high flammability and high risk of ignition at the time of leakage has attracted attention. The solid-state electrolyte is contained in the full solid-state secondary battery in the form of a solid-state electrolyte layer (electrode composite layer, solid-state electrolyte layer) in which components such as a solid-state electrolyte are adhered to each other by a binding material.

[0004] Here, when the solid-state electrolyte layer is formed, a slurry composition for a solid-state electrolyte layer prepared using a binder composition containing a polymer as a binding material is used.

[0005] Furthermore, in the past, in order to improve the performance of a full solid-state secondary battery, a polymer used as a binding material and a binder composition containing the polymer have been improved (for example, refer to Patent Documents 1 to 3).

[0006] PRIOR ART DOCUMENTS

[0007] PATENT DOCUMENTS

[0008] Patent Document 1: International Publication No. 2016 / 125716;

[0009] Patent Document 2: International Publication No. 2012 / 026583;

[0010] Patent Document 3: International Publication No. 2019 / 007875. SUMMARY

[0011] PROBLEMS TO BE SOLVED BY THE INVENTION

[0012] However, the above-described conventional binder composition has room for improvement in terms of improving the dispersibility of the slurry composition and enabling the full solid-state secondary battery to exhibit excellent cycle characteristics.

[0013] Accordingly, an object of the present application is to provide a binder composition for a full solid-state secondary battery, which can produce a slurry composition for a full solid-state secondary battery having excellent dispersibility, and can form a solid electrolyte-containing layer that can cause a full solid-state secondary battery to exhibit excellent cycle characteristics.

[0014] Further, an object of the present application is to provide a slurry composition for a full solid-state secondary battery, which has excellent dispersibility, and can form a solid electrolyte-containing layer that can cause a full solid-state secondary battery to exhibit excellent cycle characteristics.

[0015] Furthermore, an object of the present application is to provide a solid electrolyte-containing layer that can cause a full solid-state secondary battery to exhibit excellent cycle characteristics, and a full solid-state secondary battery having excellent cycle characteristics.

[0016] Means for solving the problem

[0017] The present inventors have conducted intensive studies with a view to solving the above problems. Then, the present inventors have newly found that if a binder composition containing a prescribed polymer and a prescribed aromatic halide, and having a content of the aromatic halide relative to a content of the polymer within a prescribed range is used, the dispersibility of a slurry composition can be sufficiently ensured, and a full solid-state secondary battery can be caused to exhibit excellent cycle characteristics, thereby completing the present application.

[0018] That is, an object of the present application is to advantageously solve the above problems, and a binder composition for a full solid-state secondary battery of the present application is characterized by containing a polymer and an aromatic halide, the above polymer containing a nitrile group-containing monomer unit in a proportion of 10 mass% or more and 35 mass% or less, and containing a (meth)acrylate monomer unit in a proportion of 15 mass% or more and 40 mass% or less, the above aromatic halide having a structure in which 2 or more and 4 or less halogen atoms are directly bonded to an aromatic ring, and a content of the above aromatic halide relative to a content of the above polymer is 5 mass ppm or more and 3000 mass ppm or less. If a binder composition containing the above polymer and the aromatic halide having the above prescribed structure, and having a ratio of the content of the polymer to the content of the aromatic halide within the above range is used, a slurry composition having excellent dispersibility and a solid electrolyte-containing layer that can cause a full solid-state secondary battery to exhibit excellent cycle characteristics can be obtained.

[0019] Further, in the present application, the content of the aromatic halide can be measured by gas chromatography.

[0020] Further, in the present application, "(meth)acrylic acid group" means an acrylic acid group and / or a methacrylic acid group.

[0021] Furthermore, in this invention, "containing monomer units" means "containing structural units derived from the monomer in a polymer obtained using the monomer." Additionally, in this invention, the content (mass %) of "structural units" (containing "monomer units") in the polymer can be determined using... 1 Measured by nuclear magnetic resonance (NMR) methods such as H-NMR.

[0022] Here, the binder composition for all-solid-state secondary batteries of the present invention preferably contains a metal belonging to the 5th period and groups 3 to 14 of the periodic table in an amount of 0.5 ppm by mass or more and 200 ppm by mass or less relative to the content of the polymer described above. If the binder composition contains a metal belonging to the 5th period and groups 3 to 14 of the periodic table (hereinafter, sometimes simply referred to as "5th period metal") in an amount within the above range, the cycle characteristics of the all-solid-state secondary battery can be further improved, and the output characteristics can be improved.

[0023] Furthermore, in this invention, the content of various metals contained in the adhesive composition can be determined by high-frequency inductively coupled plasma atomic emission spectrometry (ICP-AES). Specifically, this content can be determined using the method described in the examples.

[0024] Furthermore, the binder composition for all-solid-state secondary batteries of the present invention preferably contains a metal belonging to Group 1 or Group 2 of the periodic table in an amount of 5 ppm by mass or more and 3000 ppm by mass or less relative to the content of the polymer described above. If the binder composition contains a metal belonging to Group 1 or Group 2 of the periodic table (hereinafter, sometimes simply referred to as "Group 1 or 2 metals") in an amount within the above range, the water resistance of the solid electrolyte can be ensured, and the dispersibility of the slurry composition can be further improved, thereby improving the cell characteristics of the all-solid-state secondary battery (i.e., reducing the IV resistance of the all-solid-state secondary battery while improving cycle characteristics and output characteristics).

[0025] Furthermore, the binder composition for all-solid-state secondary batteries of the present invention preferably has an iodine value of 0.5 mg / 100 mg or more and 20 mg / 100 mg or less for the polymer described above. If the iodine value of the polymer is within the above range, the adhesion of the solid electrolyte layer can be improved, and the oxidative degradation of the electrode active material (especially the positive electrode active material) can be suppressed, thereby further improving the cycle characteristics of the all-solid-state secondary battery.

[0026] Furthermore, in this invention, the "iodine value" of the polymer can be determined using the method described in the examples.

[0027] Here, the binder composition for all-solid-state secondary batteries of the present invention preferably has an alkyl group having 4 or more and 9 or less carbon atoms in which it is bonded to the non-carbonyl oxygen atom of the (meth)acrylate monomer unit. If a structural unit from a (meth)acrylate monomer having 4 or more and 9 or less carbon atoms in which it is bonded to the non-carbonyl oxygen atom is used as the (meth)acrylate monomer unit, the dispersibility of the slurry composition and the cycle characteristics of the all-solid-state secondary battery can be further improved.

[0028] Furthermore, the binder composition for all-solid-state secondary batteries of the present invention may also contain a solvent.

[0029] Furthermore, in this invention, the aromatic halides having a structure in which two or more but less than four halogen atoms are directly bonded to the aromatic ring are not included in the "solvent".

[0030] Furthermore, the object of the present invention is to advantageously solve the above-mentioned problems. The slurry composition for all-solid-state secondary batteries of the present invention is characterized by comprising a solid electrolyte and a binder composition for all-solid-state secondary batteries containing a solvent. The slurry composition containing a solid electrolyte, the polymer, the aromatic halide, and a solvent, and wherein the ratio of the polymer to the aromatic halide is within the above-mentioned range, exhibits excellent dispersibility. Moreover, if the slurry composition is used, a solid electrolyte layer can be formed that enables the all-solid-state secondary battery to exhibit excellent cycle characteristics.

[0031] Here, the all-solid-state secondary battery slurry composition of the present invention may also contain electrode active materials. The all-solid-state secondary battery slurry composition containing electrode active materials can be used as a slurry composition for electrode composite material layers.

[0032] Furthermore, the all-solid-state secondary battery slurry composition of the present invention, which contains electrode active materials, preferably also contains carbon nanotubes. If an electrode composite material layer slurry composition containing carbon nanotubes (hereinafter sometimes simply referred to as "CNT") is used, the cell characteristics of the all-solid-state secondary battery can be further improved.

[0033] Furthermore, the object of the present invention is to advantageously solve the above-mentioned problems. The solid-state electrolyte layer of the present invention is characterized by being formed using any of the aforementioned all-solid-state secondary battery slurry compositions. The solid-state electrolyte layer formed using any of the aforementioned slurry compositions enables the all-solid-state secondary battery to exhibit excellent cycle characteristics.

[0034] Furthermore, the object of the present invention is to advantageously solve the above-mentioned problems. The all-solid-state secondary battery of the present invention is characterized by having the aforementioned solid electrolyte layer. The all-solid-state secondary battery having the aforementioned solid electrolyte layer exhibits excellent cell characteristics, such as cycle characteristics.

[0035] Invention Effects

[0036] According to the present invention, a binder composition for all-solid-state secondary batteries can be provided, which can prepare a slurry composition for all-solid-state secondary batteries with excellent dispersibility, and can form a solid electrolyte layer that enables all-solid-state secondary batteries to exhibit excellent cycle characteristics.

[0037] Furthermore, according to the present invention, a slurry composition for all-solid-state secondary batteries can be provided, which has excellent dispersibility and can form a solid electrolyte layer that enables all-solid-state secondary batteries to exhibit excellent cycle characteristics.

[0038] Furthermore, according to the present invention, it is possible to provide a solid electrolyte layer that enables all-solid-state secondary batteries to exhibit excellent cycle characteristics, and an all-solid-state secondary battery with excellent cycle characteristics. Detailed Implementation

[0039] The embodiments of the present invention will now be described in detail.

[0040] The binder composition for all-solid-state secondary batteries of the present invention is used in the preparation of a slurry composition for all-solid-state secondary batteries. Here, the slurry composition for all-solid-state secondary batteries of the present invention is used in the formation of a solid electrolyte layer, such as an electrode composite material layer or a solid electrolyte layer, used in all-solid-state secondary batteries such as all-solid-state lithium-ion secondary batteries. That is, the slurry composition for all-solid-state secondary batteries of the present invention can be used as a slurry composition for an electrode composite material layer and a slurry composition for a solid electrolyte layer. Furthermore, the solid electrolyte layer of the present invention is formed using the slurry composition for all-solid-state secondary batteries of the present invention. Consequently, the all-solid-state secondary battery of the present invention has the solid electrolyte layer of the present invention.

[0041] (Binder composition for all-solid-state secondary batteries)

[0042] The adhesive composition of the present invention comprises a polymer and an aromatic halide having two or more but less than four halogen atoms directly bonded to an aromatic ring, and may also optionally contain at least one selected from period 5 metals, group 1 to 2 metals, solvents and other components.

[0043] Here, the adhesive composition of the present invention is characterized in that the polymer contains nitrile monomer units in a proportion of 10% to 35% by mass and (meth)acrylate monomer units in a proportion of 15% to 40% by mass, and the content of the aromatic halogen is 5 ppm by mass or more and 3000 ppm by mass or less relative to the content of the polymer.

[0044] Furthermore, in the binder composition of the present invention, since the proportions of nitrile monomer units and (meth)acrylate monomer units in the polymer are within the above-mentioned ranges, and the content of aromatic halides relative to the polymer is within the above-mentioned ranges, if the binder composition is used, a slurry composition with excellent dispersibility and a solid electrolyte layer that enables all-solid-state secondary batteries to exhibit excellent cycle characteristics can be obtained.

[0045] <Polymer>

[0046] The polymer functions as a bonding material in a slurry composition containing a solid electrolyte, formed by using a binder composition.

[0047] <<Composition>>

[0048] Here, the polymer needs to contain nitrile monomer units in a proportion of 10% to 35% by mass and (meth)acrylate monomer units in a proportion of 15% to 40% by mass. Alternatively, the polymer may also contain structural units other than nitrile monomer units and (meth)acrylate monomer units (other structural units).

[0049] [Contains nitrile-based monomer units]

[0050] Examples of nitrile monomers capable of forming nitrile-containing monomer units include acrylonitrile; α-haloacrylonitrile such as α-chloroacrylonitrile and α-bromoacrylonitrile; and α-alkylacrylonitrile such as methacrylonitrile and α-ethylacrylonitrile. These can be used alone or in combination of two or more. Among these, acrylonitrile is preferred.

[0051] Here, in all structural units contained in the polymer, with all structural units as 100% by mass, the proportion of nitrile-containing monomer units needs to be 10% by mass or more and 35% by mass or less, preferably 12% by mass or more, more preferably 15% by mass or more, further preferably 20% by mass or more, preferably 30% by mass or less, more preferably 28.5% by mass or less, and even more preferably 27% by mass or less. When the proportion of nitrile-containing monomer units in all structural units of the polymer is less than 10% by mass, the polymer cannot be sufficiently adsorbed onto the solid electrolyte, and the solid electrolyte cannot be well dispersed in the slurry composition. Therefore, the dispersibility of the slurry composition decreases. On the other hand, when the proportion of nitrile-containing monomer units in all structural units of the polymer exceeds 35% by mass, the solubility in the solvent contained in the slurry composition decreases, and the dispersibility of the slurry composition decreases. Moreover, if the proportion of nitrile-containing monomer units in all structural units of the polymer is 10% by mass or more and 35% by mass or less, it is possible to prepare a slurry composition with excellent dispersibility and improve the cell characteristics (cycle characteristics, etc.) of the all-solid-state secondary battery.

[0052] [(meth)acrylate monomer unit]

[0053] Examples of (meth)acrylate monomers capable of forming (meth)acrylate monomer units include: methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, and cyclohexyl acrylate, etc.; alkoxy acrylates such as 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate; 2-(perfluorobutyl)ethyl acrylate and 2-(perfluoropentyl)ethyl acrylate, etc.; methyl methacrylate, methacrylic acid... Ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, tridecyl methacrylate, n-tetradecyl methacrylate, stearyl methacrylate, 2-ethylhexyl methacrylate, and cyclohexyl methacrylate, etc., are all alkyl methacrylates; 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, etc., are alkoxy methacrylates; 2-(perfluorobutyl)ethyl methacrylate, 2-(perfluoropentyl)ethyl methacrylate, etc., are 2-(perfluoroalkyl)ethyl methacrylate. These can be used alone or in combination of two or more. Furthermore, as (meth)acrylate monomers, alkyl (meth)acrylate monomers (hereinafter sometimes simply referred to as "C4-C9 (meth)acrylate alkyl monomers") constituting the alkyl group bonded to the non-carbonyl oxygen atom are preferred. By using C4-C9 (meth)acrylate alkyl ester monomers, the solid electrolyte can be well dispersed in the slurry composition, further improving the dispersibility of the slurry composition. Furthermore, it can impart appropriate flexibility to the solid electrolyte layer, further improving the cell characteristics of the all-solid-state secondary battery. And, as C4-C9 (meth)acrylate alkyl ester monomers, examples such as n-butyl acrylate, 2-ethylhexyl acrylate, and cyclohexyl acrylate are preferred.

[0054] Here, in all structural units contained in the polymer, with all structural units as 100% by mass, the proportion of (meth)acrylate monomer units needs to be 15% by mass or more and 40% by mass or less, preferably 20% by mass or more, more preferably 25% by mass or more, further preferably 30% by mass or more, preferably 37.5% by mass or less, and more preferably 35% by mass or less. When the proportion of (meth)acrylate monomer units in all structural units of the polymer is less than 15% by mass, the adhesion of the solid electrolyte layer decreases. On the other hand, when the proportion of (meth)acrylate monomer units in all structural units of the polymer exceeds 40% by mass, the flexibility of the solid electrolyte layer cannot be sufficiently ensured. Moreover, if the proportion of (meth)acrylate monomer units in all structural units of the polymer is 15% by mass or more and 40% by mass or less, a solid electrolyte layer with excellent adhesion and flexibility can be formed, improving the cell characteristics (cycle characteristics, etc.) of the all-solid-state secondary battery.

[0055] [Other structural units]

[0056] As for other structural units, there are no particular limitations as long as they are derived from monomers that can copolymerize with the aforementioned nitrile-containing monomers and (meth)acrylate monomers. From the viewpoint of ensuring the dispersibility of the slurry composition and the flexibility of the solid electrolyte layer, and improving the battery cell characteristics of the all-solid-state secondary battery, diene-based monomer units are preferred.

[0057] Examples of diene monomers capable of forming diene monomer units include aliphatic conjugated diene monomers such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. These can be used individually or in combination of two or more.

[0058] In addition, in this invention, the "diene monomer unit" also includes a structural unit (hydride unit) obtained by further hydrogenating the monomer unit contained in the polymer obtained using diene monomers.

[0059] Furthermore, among the aforementioned diene monomers, 1,3-butadiene and isoprene are preferred. In other words, as diene monomer units, 1,3-butadiene units, isoprene units, 1,3-butadiene hydride units, and isoprene hydride units are preferred, and 1,3-butadiene hydride units and isoprene hydride units are more preferred.

[0060] Here, when the polymer contains diene monomer units, with all structural units representing 100% by mass, the proportion of diene monomer units in all structural units contained in the polymer is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, particularly preferably 40% by mass or more, preferably 75% by mass or less, more preferably 60% by mass or less, and further preferably 50% by mass or less. If the proportion of diene monomer units in all structural units is 10% by mass or more, the polymer can be well adsorbed onto electrode active materials and conductive materials, thus further improving the dispersibility of the slurry composition (especially the slurry composition for electrode composite material layers). On the other hand, if the proportion of diene monomer units in all structural units is 75% by mass or less, the adhesion of the solid electrolyte layer can be sufficiently ensured. Therefore, if the proportion of diene monomer units in all structural units of the polymer is 10% by mass or more and 75% by mass or less, the cell characteristics of the all-solid-state secondary battery can be further improved.

[0061] <<Iodine value>>

[0062] The iodine value of the polymer is preferably 0.5 mg / 100 mg or more, more preferably 1.0 mg / 100 mg or more, even more preferably 2.0 mg / 100 mg or more, preferably 20 mg / 100 mg or less, more preferably 15 mg / 100 mg or less, and even more preferably 10 mg / 100 mg or less. If the iodine value of the polymer is 0.5 mg / 100 mg or more, the strength of the polymer can be ensured, and the adhesion of the solid electrolyte layer can be improved. If it is 20 mg / 100 mg or less, the oxidative degradation of the electrode active materials (especially the positive electrode active materials) can be suppressed. Therefore, if the iodine value of the polymer is 0.5 mg / 100 mg or more and 20 mg / 100 mg or less, the cycle characteristics of the all-solid-state secondary battery can be further improved.

[0063] <<Weight-average molecular weight (Mw)>>

[0064] The weight-average molecular weight of the polymer is preferably 10,000 or more, more preferably 50,000 or more, even more preferably 100,000 or more, preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. If the weight-average molecular weight of the polymer is 10,000 or more, the adhesion of the solid electrolyte layer can be improved, and the cycle characteristics of the all-solid-state secondary battery can be further improved. On the other hand, if the weight-average molecular weight of the polymer is 2,000,000 or less, the dispersibility of the slurry composition can be further improved.

[0065] <<Molecular weight distribution (Mw / Mn)>>

[0066] The molecular weight distribution of the polymer (the ratio of weight-average molecular weight to number-average molecular weight) is preferably 1.5 or more, more preferably 2.0 or more, even more preferably 2.5 or more, preferably 5.5 or less, even more preferably 4.5 or less. If the molecular weight distribution of the polymer is 1.5 or more and 5.5 or less, the dispersibility of the slurry composition can be further improved, the adhesion of the solid electrolyte layer can be improved, and the cell characteristics of the all-solid-state secondary battery can be further improved.

[0067] <<Preparation Method>>

[0068] There are no particular limitations on the method of preparing the polymer. For example, the polymer can be prepared by arbitrarily hydrogenating (hydrogenating) a monomer composition containing the above-mentioned monomers.

[0069] In this invention, the proportion of each monomer in the monomer composition can be determined based on the proportion of each monomer unit in the polymer.

[0070] There are no particular restrictions on the polymerization method; any method can be used, such as solution polymerization, suspension polymerization, bulk polymerization, or emulsion polymerization. In each polymerization method, known emulsifiers and polymerization initiators can be used as needed. Here, as emulsifiers, nonionic emulsifiers such as polyoxyethylene lauryl ether can be used, or emulsifiers containing group 1-2 metals such as sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl diphenyl ether sulfonate, and sodium polyoxyethylene alkyl ether sulfate can be used.

[0071] There are no particular restrictions on the hydrogenation method; known hydrogenation methods such as oil-based hydrogenation or water-based hydrogenation can be used. Furthermore, as for the catalyst used in hydrogenation, any known selective hydrogenation catalyst can be used without limitation; palladium-based or rhodium-based catalysts can be used. Two or more of these can be used in combination.

[0072] Alternatively, hydrogenation can be carried out using, for example, the method described in Japanese Patent No. 4509792. Specifically, the hydrogenation of the polymer can also be carried out after a metathesis reaction of the polymer in the presence of a catalyst and a co-olefin.

[0073] Here, known ruthenium-based catalysts can be used as catalysts for the metathesis reaction. Among these, Grubbs catalysts such as bis(tricyclohexylphosphine)benzylmethylruthenium dichloride and 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinedimethyl)(dichlorophenylmethylene)(tricyclohexylphosphine)ruthenium are preferred. Furthermore, olefins with 2 to 16 carbon atoms, such as ethylene, isobutylene, and 1-hexene, can be used as copolyolefins. Moreover, known homogeneous hydrogenation catalysts, such as the Wilkinson catalyst ((PPh3)3RhCl), can be used as hydrogenation catalysts after the metathesis reaction.

[0074] Alternatively, when the obtained polymer is solidified and recycled, coagulants containing group 1 to 2 metals, such as calcium chloride, can be used.

[0075] <Aromatic Halides>

[0076] The binder composition of the present invention comprises an aromatic halide having a structure in which two or more but less than four halogen atoms are directly bonded to an aromatic ring. It is presumably because such aromatic halides possess high polarity that the wettability of the solid electrolyte in the slurry composition in a solvent is improved when a binder composition containing such an aromatic halide is used to prepare the slurry composition. Therefore, the dispersibility of the slurry composition can be improved. Furthermore, unexpected side reactions are less likely to occur between the aforementioned aromatic halide with the defined structure and the solid electrolyte. Therefore, if a binder composition containing such an aromatic halide is used, a slurry composition with excellent dispersibility can be prepared, and an all-solid-state secondary battery with excellent cell characteristics such as cycle performance can be manufactured.

[0077] Here, aromatic halides are not particularly limited as long as they have a structure in which two or more but no more than four halogen atoms are directly bonded to an aromatic ring. Examples include aromatic chlorides, aromatic fluorides, and aromatic bromides. Among these, aromatic chlorides are preferred from the viewpoint of further improving the dispersibility of the slurry composition and enabling the all-solid-state secondary battery to exhibit superior battery cell characteristics.

[0078] Furthermore, as aromatic chlorides, compounds in which two or more but less than four hydrogen atoms on an aromatic hydrocarbon ring, such as a benzene ring, are replaced by chlorine atoms are preferred. Examples of such compounds include dichlorobenzene compounds such as 1,2-dichlorobenzene, 1,3-dichlorobenzene, and 1,4-dichlorobenzene; trichlorobenzene compounds such as 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, and 1,3,5-trichlorobenzene; and tetrachlorobenzene compounds such as 1,2,3,4-tetrachlorobenzene and 1,2,4,5-tetrachlorobenzene. Among these, dichlorobenzene compounds are preferred, and 1,2-dichlorobenzene is more preferred, from the viewpoint of further improving the dispersibility of the slurry composition and the cell characteristics of the all-solid-state secondary battery, and from improving the adhesion of the solid electrolyte layer.

[0079] In addition, aromatic halides can be used alone or in combination of two or more.

[0080] Furthermore, the content of aromatic halides in the binder composition relative to the content of the polymer needs to be 5 ppm by mass or more and 3000 ppm by mass or less, preferably 10 ppm by mass or more, more preferably 15 ppm by mass or more, even more preferably 50 ppm by mass or more, preferably 1000 ppm by mass or less, and more preferably 500 ppm by mass or less. When the content of aromatic halides relative to the polymer is less than 5 ppm by mass, the dispersibility of the slurry composition decreases, and it is impossible to obtain an all-solid-state secondary battery with excellent cell characteristics such as cycle characteristics. On the other hand, when the content of aromatic halides relative to the polymer exceeds 3000 ppm by mass, especially when the slurry composition contains electrode active materials (i.e., when the slurry composition is a slurry composition for electrode composite material layers), it is difficult to disperse the electrode active materials well, and the dispersibility of the slurry composition decreases. In addition, when the content of aromatic halides relative to the polymer exceeds 3000 ppm by mass, halogen gas may be generated inside the all-solid-state secondary battery, which may damage the cell characteristics.

[0081] Therefore, if the content of aromatic halides in the binder composition is 5 ppm by mass or more and 3000 ppm by mass or less relative to the content of the polymer, the dispersibility of the slurry composition can be improved, and the all-solid-state secondary battery can perform well in terms of cycle characteristics and other battery cell characteristics.

[0082] Furthermore, there are no particular limitations on the method of incorporating aromatic halides into the adhesive composition. For example, during the preparation of the polymer, a reaction solvent containing aromatic halides can be used for polymerization and / or hydrogenation, or an aromatic halides can be added after the preparation of the polymer, thereby preparing an adhesive composition containing aromatic halides.

[0083] <Metals belonging to period 5 of the periodic table and groups 3 to 14 of the periodic table>

[0084] The binder composition of the present invention preferably contains a 5-cycle metal. It is speculated that by including a 5-cycle metal in the binder composition, the electronic resistance of the all-solid-state secondary battery can be reduced, thereby improving the cell characteristics of the all-solid-state secondary battery.

[0085] Here, from the viewpoint of further improving the cell characteristics of all-solid-state secondary batteries, ruthenium (Ru), rhodium (Rh), and palladium (Pd) are preferred as five-cycle metals. These can be used individually or in combination of two or more.

[0086] Furthermore, the content of the 5-cycle metal in the binder composition relative to the content of the polymer is preferably 0.5 ppm by mass or more, more preferably 1 ppm by mass or more, even more preferably 2 ppm by mass or more, particularly preferably 8 ppm by mass or more, preferably 200 ppm by mass or less, more preferably 150 ppm by mass or less, and even more preferably 100 ppm by mass or less. If the content of the 5-cycle metal relative to the polymer is 1 ppm by mass or more, the cell characteristics of the all-solid-state secondary battery can be further improved. On the other hand, if the content of the 5-cycle metal relative to the polymer is 200 ppm by mass or less, the cycle characteristics of the all-solid-state secondary battery can be sufficiently improved, and short circuits between electrodes due to the deposition of the 5-cycle metal will not occur.

[0087] Furthermore, there are no particular limitations on the method for incorporating a 5-period metal into the binder composition. For example, when preparing the polymer, catalysts containing a 5-period metal, such as the palladium-based catalysts, rhodium-based catalysts, ruthenium catalysts, and Wilkinson catalysts described above, can be used. Alternatively, after preparing the polymer, substances capable of supplying the 5-period metal (e.g., palladium-based compounds such as organic complexes and organic salts of palladium, rhodium-based compounds such as organic complexes and organic salts of rhodium, and ruthenium-based compounds such as organic complexes and organic salts of ruthenium) can be added, thereby enabling the preparation of a binder composition containing a 5-period metal.

[0088] <Metals belonging to Group 1 or Group 2 of the periodic table>

[0089] The binder composition of the present invention preferably contains Group 1 to 2 metals. By including Group 1 to 2 metals in the binder composition, the cell characteristics of the all-solid-state secondary battery can be improved. Although the reason is not yet certain, it is speculated that this is because: in the slurry composition and in the solid electrolyte layer, the Group 1 to 2 metals are adsorbed onto the surface of the solid electrolyte through electrostatic interactions and thus cover the surface, thereby inhibiting the reaction between moisture and the solid electrolyte and suppressing the degradation of the solid electrolyte caused by such reaction.

[0090] Examples of group 1-2 metals include sodium (Na), potassium (K), lithium (Li), magnesium (Mg), and calcium (Ca). These can be used individually or in combination of two or more. Among these, sodium and calcium are preferred from the viewpoint of further improving the cell characteristics of all-solid-state secondary batteries.

[0091] Furthermore, the content of Group 1-2 metals in the binder composition relative to the content of the polymer is preferably 5 ppm by mass or more, more preferably 10 ppm by mass or more, even more preferably 50 ppm by mass or more, particularly preferably 110 ppm by mass or more, preferably 3000 ppm by mass or less, more preferably 2000 ppm by mass or less, and even more preferably 1000 ppm by mass or less. If the content of Group 1-2 metals relative to the polymer is 5 ppm by mass or more, the cell characteristics of the all-solid-state secondary battery can be further improved. On the other hand, if the content of Group 1-2 metals relative to the polymer is 3000 ppm by mass or less, the Group 1-2 metals will not cause the solid electrolyte and polymer to agglomerate, thus ensuring sufficient dispersibility of the slurry composition.

[0092] Furthermore, the method for incorporating Group 1-2 metals into the adhesive composition is not particularly limited. For example, during polymer preparation, an adhesive composition containing Group 1-2 metals can be prepared by using the aforementioned emulsifier and / or coagulant containing Group 1-2 metals, or by adding a substance capable of supplying Group 1-2 metals (e.g., a hydroxide containing Group 1-2 metals) after polymer preparation. Additionally, for example, by passing the polymer through an ion exchange resin, the amount of Group 1-2 metals contained in the resulting adhesive composition can be reduced.

[0093] <Solvent>

[0094] The binder composition of the present invention optionally includes a solvent. Furthermore, an organic solvent with 6 or more carbon atoms is preferably used as the solvent. It is anticipated that by using an organic solvent with 6 or more carbon atoms in the binder composition, aggregation of polymers and solid electrolytes in the slurry composition prepared using this binder composition will be suppressed, further improving the dispersibility of the slurry composition. Moreover, organic solvents with 6 or more carbon atoms are less likely to react with solid electrolytes and have high boiling points, thus exhibiting excellent operability. Therefore, by using an organic solvent with 6 or more carbon atoms as the solvent, solid electrolytes and the like can be uniformly disposed in the solid electrolyte layer, improving the cell characteristics of all-solid-state secondary batteries.

[0095] <<Organic solvents with 6 or more carbon atoms>>

[0096] Examples of organic solvents having 6 or more carbon atoms include xylene (8 carbon atoms), butyl butyrate (8 carbon atoms), n-butyl ether (8 carbon atoms), diisobutyl ketone (9 carbon atoms), hexyl butyrate (10 carbon atoms), cyclopentyl methyl ether (6 carbon atoms), hexane (6 carbon atoms), cyclohexane (6 carbon atoms), cyclohexanone (6 carbon atoms), butyl acetate (6 carbon atoms), ε-caprolactone (6 carbon atoms), and isobutyl isobutyrate (8 carbon atoms). These can be used individually or in combination of two or more. Furthermore, from the viewpoint of further improving the dispersibility of the slurry composition and further improving the cell characteristics of the all-solid-state secondary battery, xylene, butyl butyrate, diisobutyl ketone, cyclopentyl methyl ether, and isobutyl isobutyrate are more preferred.

[0097] <<Other Solvents>>

[0098] Furthermore, the adhesive composition of the present invention may contain a solvent other than the organic solvents with 6 or more carbon atoms mentioned above (other solvents) as a solvent. As such other solvents, organic solvents with 5 or fewer carbon atoms, such as cyclopentane and ethyl acetate, can be used. In addition, one other solvent may be used alone, or two or more may be used in combination.

[0099] However, from the viewpoint of fully improving the dispersibility of the slurry composition and the cell characteristics of the all-solid-state secondary battery, the proportion of organic solvents with 6 or more carbon atoms in the solvent is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass (i.e., substantially free of other solvents).

[0100] <Preparation Method of Adhesive Composition>

[0101] The method for preparing the binder composition of the present invention is not particularly limited. For example, an aromatic halide, a substance capable of supplying a fifth-period metal, a substance capable of supplying a group 1 to 2 metal, a solvent, and / or other components can be added as needed to a polymer obtained by polymerization as described above and by any metathesis and hydrogenation. In addition, as other components that can be arbitrarily included in the binder composition, the same components as those described later in the section on "Slurry Composition for All-Solid-State Secondary Batteries" can be cited.

[0102] (Slurry composition for all-solid-state secondary batteries)

[0103] The slurry composition for all-solid-state secondary batteries of the present invention comprises at least a solid electrolyte and a binder composition for all-solid-state secondary batteries of the present invention containing a solvent. More specifically, the slurry composition of the present invention contains a solid electrolyte, the aforementioned polymer, the aforementioned aromatic halide, and the aforementioned solvent, and optionally contains an electrode active material and other components. Furthermore, since the slurry composition of the present invention contains the binder composition of the present invention, it exhibits excellent dispersibility. In addition, if the slurry composition is used, a solid electrolyte-containing layer can be formed that improves the cell characteristics such as the cycle characteristics of the all-solid-state secondary battery.

[0104] <Solid Electrolyte>

[0105] As a solid electrolyte, there are no particular limitations as long as it contains solid particles with ion conductivity, and inorganic solid electrolytes are preferred.

[0106] There are no particular limitations on the inorganic solid electrolyte; crystalline inorganic ion conductors, amorphous inorganic ion conductors, or mixtures thereof can be used. Furthermore, for example, in the case of an all-solid-state secondary battery being an all-solid-state lithium-ion secondary battery, crystalline inorganic lithium-ion conductors, amorphous inorganic lithium-ion conductors, or mixtures thereof can generally be used as the inorganic solid electrolyte. From the viewpoint of forming a solid electrolyte layer with superior ion conductivity, the inorganic solid electrolyte preferably includes at least one of a sulfide-based inorganic solid electrolyte and an oxide-based inorganic solid electrolyte.

[0107] Furthermore, the following description is provided as an example of a slurry composition for all-solid-state secondary batteries that is a slurry composition for all-solid-state lithium-ion secondary batteries, but the present invention is not limited to the following example.

[0108] Furthermore, examples of crystalline inorganic lithium-ion conductors include Li3N and LISICON (Li 14 Zn(GeO4)4), perovskite type (e.g., Li) 0.5 La 0.5 TiO3), garnet type (e.g., Li7La3Zr2O) 12 ), LIPON (Li 3+y PO 4-x N x Thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), argyrodite type (e.g., Li 5.6 PS 4.4 Cl 1.8 )wait.

[0109] The aforementioned crystalline inorganic lithium-ion conductors can be used alone or in combination of two or more.

[0110] Furthermore, as an amorphous inorganic lithium-ion conductor, there are no particular limitations as long as it contains sulfur atoms and has ionic conductivity. More specifically, examples include amorphous substances formed by combining raw materials containing glass Li-Si-SO, Li-PS, and sulfides containing Li2S and elements from Groups 13 to 15 of the periodic table.

[0111] Examples of elements from Groups 13 to 15 include Al, Si, Ge, P, As, and Sb. Specifically, examples of sulfides of these elements include Al₂S₃, SiS₂, GeS₂, P₂S₃, P₂S₅, As₂S₃, and Sb₂S₃. Furthermore, methods for synthesizing amorphous inorganic lithium-ion conductors using a raw material composition include amorphization methods such as mechanical grinding and melt quenching. Moreover, for amorphous inorganic lithium-ion conductors formed using a raw material composition containing Li₂S and sulfides of elements from Groups 13 to 15 of the periodic table, Li₂S-P₂S₅, Li₂S-SiS₂, Li₂S-GeS₂, or Li₂S-Al₂S₃ are preferred, with Li₂S-P₂S₅ being more preferred.

[0112] The aforementioned amorphous inorganic lithium-ion conductors can be used alone or in combination of two or more.

[0113] From the perspective of forming a solid electrolyte layer with superior ion conductivity, the inorganic solid electrolyte for all-solid-state lithium-ion secondary batteries is preferably an amorphous sulfide containing Li and P, such as Li7La3Zr2O. 12 Amorphous sulfides containing Li and P, as well as Li7La3Zr2O 12 Because of the high conductivity of lithium ions, using them as inorganic solid electrolytes can reduce the IV resistance of all-solid-state secondary batteries and improve output characteristics.

[0114] Furthermore, from the viewpoint of reducing the IV resistance of the battery and improving output characteristics, amorphous sulfides containing Li and P are more preferably sulfide glasses containing Li₂S and P₂S₅, and particularly preferably sulfide glasses manufactured from a mixture of Li₂S and P₂S₅ with a Li₂S:P₂S₅ molar ratio of 65:35 to 85:15. Moreover, amorphous sulfides containing Li and P are preferably sulfide glass-ceramics obtained by reacting a mixture of Li₂S and P₂S₅ with a Li₂S:P₂S₅ molar ratio of 65:35 to 85:15 using a mechanochemical method. Additionally, from the viewpoint of maintaining high lithium-ion conductivity, the mixed raw material preferably has a Li₂S:P₂S₅ molar ratio of 68:32 to 80:20.

[0115] In addition, without reducing ionic conductivity, the inorganic solid electrolyte contains, in addition to the aforementioned Li₂S and P₂S₅, at least one sulfide selected from Al₂S₃, B₂S₃, and SiS₂ as a starting material. The addition of such a sulfide stabilizes the glass composition of the inorganic solid electrolyte.

[0116] Similarly, in addition to Li2S and P2S5, inorganic solid electrolytes may also contain at least one lithium ortho-oxo acid selected from Li3PO4, Li4SiO4, Li4GeO4, Li3BO3, and Li3AlO3. The inclusion of this lithium ortho-oxo acid can stabilize the glass composition of the inorganic solid electrolyte.

[0117] The above-mentioned solid electrolytes can be used alone or in combination of two or more.

[0118] Furthermore, the number-average particle size of the aforementioned solid electrolyte is preferably 0.1 μm or more, more preferably 0.3 μm or more, even more preferably 0.5 μm or more, preferably 10 μm or less, more preferably 7.5 μm or less, and even more preferably 5.0 μm or less. If the number-average particle size of the solid electrolyte is 0.1 μm or more, the dispersibility of the slurry composition can be further improved; if it is 10 μm or less, the IV resistance of the all-solid-state secondary battery can be reduced, thus significantly improving the characteristics of the battery cell.

[0119] Furthermore, in this invention, the number-average particle size of the solid electrolyte can be measured using the method described in the examples.

[0120] <Adhesive Composition>

[0121] The adhesive composition of the present invention, which contains at least the polymer, the aromatic halide and the solvent described above, is used as the adhesive composition.

[0122] In addition, there is no particular limitation on the ratio of solid electrolyte to binder composition.

[0123] For example, the amount of polymer from the binder composition contained in the slurry composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and most preferably 10 parts by mass or less, relative to 100 parts by mass of the solid electrolyte. If the polymer content in the slurry composition is 0.1 parts by mass or more relative to 100 parts by mass of the solid electrolyte, the dispersibility of the slurry composition can be further improved, and the cell characteristics of the all-solid-state secondary battery can be sufficiently improved. If the polymer content in the slurry composition is 20 parts by mass or less relative to 100 parts by mass of the solid electrolyte, the ion conductivity of the solid electrolyte layer can be sufficiently ensured without excessively impairing the cell characteristics of the all-solid-state secondary battery.

[0124] <Electrode Active Materials>

[0125] Electrode active materials are substances that facilitate electron transfer in the electrodes of all-solid-state secondary batteries. Furthermore, in the case of all-solid-state secondary batteries, such as all-solid-state lithium-ion secondary batteries, substances capable of absorbing and releasing lithium are typically used as electrode active materials.

[0126] Furthermore, the following description is provided as an example of a slurry composition for all-solid-state secondary batteries that is a slurry composition for all-solid-state lithium-ion secondary batteries, but the present invention is not limited to the following example.

[0127] Furthermore, there are no particular limitations on the positive electrode active material used in all-solid-state lithium-ion secondary batteries; examples include positive electrode active materials formed from inorganic compounds and positive electrode active materials formed from organic compounds. Additionally, the positive electrode active material can also be a mixture of inorganic and organic compounds.

[0128] Examples of positive electrode active materials formed from inorganic compounds include transition metal oxides, lithium-transition metal composite oxides (lithium-containing composite metal oxides), and transition metal sulfides. Among these transition metals, Fe, Co, Ni, and Mn can be used. Specific examples of inorganic compounds used in positive electrode active materials include: lithium-containing composite metal oxides such as LiCoO2 (lithium cobalt oxide), LiNiO2, LiMnO2, LiMn2O4, LiFePO4, and LiFeVO4; transition metal sulfides such as TiS2, TiS3, and amorphous MoS2; and Cu2V2O3, amorphous V2O-P2O5, MoO3, V2O5, and V6O3. 13 Transition metal oxides, etc. These compounds can also be compounds in which elements have undergone partial substitution.

[0129] The above-mentioned positive electrode active materials formed from inorganic compounds can be used alone or in combination of two or more.

[0130] Examples of positive electrode active materials formed from organic compounds include polyaniline, polypyrrole, polybenzoxene, disulfide compounds, polysulfide compounds, and N-fluoropyridine. Salt, etc.

[0131] The above-mentioned positive electrode active materials formed from organic compounds can be used alone or in combination of two or more.

[0132] Furthermore, carbon allotropes such as graphite and coke can be used as negative electrode active materials for all-solid-state lithium-ion secondary batteries. Additionally, negative electrode active materials containing carbon allotropes can also be utilized in the form of mixtures or coatings with metals, metal salts, oxides, etc. Furthermore, as negative electrode active materials, the following can also be used: oxides or sulfates of silicon, tin, zinc, manganese, iron, nickel, etc.; metallic lithium; lithium alloys such as Li-Al, Li-Bi-Cd, and Li-Sn-Cd; lithium transition metal nitrides; polysiloxanes, etc.

[0133] The above-mentioned negative electrode active materials can be used alone or in combination of two or more.

[0134] Furthermore, the particle size of the aforementioned electrode active materials (positive electrode active material and negative electrode active material) is not particularly limited and can be the same as that of conventionally used electrode active materials. In addition, the amount of the aforementioned electrode active materials in the slurry composition is not particularly limited and can be the same as that of conventionally used electrode active materials.

[0135] <Other Ingredients>

[0136] Other components that can be included in the slurry composition are not particularly limited, and examples include binders other than conductive materials and the aforementioned polymers, dispersants, leveling agents, defoamers, and reinforcing materials. These other components are not particularly restricted as long as they do not affect the battery reaction. Furthermore, these components can be used alone or in combination of two or more in any ratio.

[0137] From the viewpoint of further improving the cell characteristics of all-solid-state secondary batteries, the slurry composition for the electrode composite layer preferably contains a conductive material.

[0138] Conductive materials are those that ensure electrical contact between the active materials of the electrodes. Furthermore, conductive materials that can be used include: carbon black (e.g., acetylene black, Ketjen black, furnace black, etc.), graphite, carbon fibers, carbon sheets, carbon nanofibers (e.g., carbon nanotubes, vapor-grown carbon fibers, etc.); and fibers and foils of various metals. These can be used individually or in combination of two or more. Among these, carbon nanotubes are preferred from the viewpoint of further improving the cell characteristics of all-solid-state secondary batteries.

[0139] As carbon nanotubes, single-walled carbon nanotubes, multi-walled carbon nanotubes (including stacked cup types), and mixtures thereof can be used.

[0140] Furthermore, the specific surface area of ​​carbon nanotubes is preferably 100 m². 2 / g or more, preferably 200m 2 / g or more, preferably 1000m 2 / g or less, preferably 500m 2 / g or less. If CNTs with a specific surface area within the above range are used, the cell characteristics of all-solid-state secondary batteries can be further improved (especially by reducing IV resistance).

[0141] In addition, the "specific surface area" of CNT refers to the nitrogen adsorption specific surface area measured using the BET (Brunauer-Emmett-Teller) method.

[0142] Furthermore, from the viewpoint of further improving the cell characteristics of all-solid-state secondary batteries, the average diameter of carbon nanotubes is preferably 0.5 nm or more and 200 nm or less.

[0143] Furthermore, from the viewpoint of further improving the cell characteristics of all-solid-state secondary batteries, the average length of carbon nanotubes is preferably 1 μm or more and 1000 μm or less.

[0144] In addition, the "average diameter" and "average length" of carbon nanotubes (CNTs) can be observed using a transmission electron microscope (TEM). The diameter (outer diameter) and length of 50 CNTs are measured based on the obtained TEM images, and the arithmetic mean of the measured values ​​is obtained.

[0145] The proportion of conductive material in the slurry composition for all-solid-state secondary batteries relative to 100 parts by mass of electrode active material is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, preferably 10 parts by mass or less, and more preferably 7 parts by mass or less. When the amount of conductive material is within the above range, sufficient electrical contact between the electrode active materials can be ensured, further improving the cell characteristics of the all-solid-state secondary battery.

[0146] <Preparation of Slurry Composition>

[0147] Furthermore, the above-mentioned slurry composition for all-solid-state secondary batteries is not particularly limited, and can be obtained by mixing the above components using, for example, any mixing method. Additionally, in the case of preparing a slurry composition for an electrode composite layer comprising an electrode active material and a conductive material, a conductive material dispersion can be prepared by premixing the conductive material with the above-mentioned polymer, and then the resulting conductive material dispersion can be mixed with the electrode active material.

[0148] (Including a solid electrolyte layer)

[0149] The solid electrolyte layer of the present invention is a layer containing a solid electrolyte. Examples of solid electrolyte layers include electrode composite material layers (positive electrode composite material layer and negative electrode composite material layer) that transfer electrons via electrochemical reactions, and solid electrolyte layers disposed between positive electrode composite material layers and negative electrode composite material layers that face each other.

[0150] Furthermore, the solid electrolyte layer of the present invention is a layer formed using the above-described all-solid-state secondary battery slurry composition. It can be formed, for example, by applying the above-described slurry composition to the surface of a suitable substrate to form a coating film, followed by drying. That is, the solid electrolyte layer of the present invention is formed from the dried product of the above-described slurry composition, and typically contains a solid electrolyte and a polymer. It may also optionally contain (some or all of which remain after drying) aromatic halides selected from at least one of group 5 metals, group 1-2 metals, electrode active materials, and other components. Additionally, the components contained in the solid electrolyte layer are those contained in the above-described slurry composition, and the proportions of these components, except for aromatic halides and solvents that can be vaporized by drying, are generally equal to the proportions in the above-described slurry composition.

[0151] Furthermore, since the solid electrolyte layer of the present invention is formed from the all-solid-state secondary battery slurry composition of the present invention, if the solid electrolyte layer is used, an all-solid-state secondary battery with excellent cycle characteristics and other battery cell characteristics can be manufactured.

[0152] <Substrate>

[0153] Here, there are no limitations on the substrate for applying the slurry composition. For example, a coating film of the slurry composition can be formed on the surface of a release substrate, the coating film can be dried to form a solid electrolyte layer, and the release substrate can be peeled off from the solid electrolyte layer. In this way, the solid electrolyte layer peeled off from the release substrate can also serve as a self-supporting film for forming battery components (e.g., electrodes, solid electrolyte layers, etc.) of an all-solid-state secondary battery.

[0154] On the other hand, from the viewpoint of improving the manufacturing efficiency of battery components by eliminating the step of stripping off the solid electrolyte layer, current collectors or electrodes can also be used as substrates. For example, when preparing an electrode composite layer, it is preferable to coat a slurry composition onto the current collector, which serves as the substrate.

[0155] <<Release Substrate>>

[0156] There are no particular limitations on the release substrate; known release substrates such as imide films can be used.

[0157] <<Current collector>>

[0158] Materials that are both conductive and electrochemically durable can be used as current collectors. Specifically, current collectors made of materials such as iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, and platinum can be used. Among these, copper foil is particularly preferred as a current collector used in the negative electrode. Furthermore, aluminum foil is particularly preferred as a current collector used in the positive electrode. In addition, the above materials can be used alone or in combination of two or more in any ratio.

[0159] <<Electrode>>

[0160] There are no particular limitations on the electrodes (positive and negative electrodes), but an example is an electrode on which an electrode composite material layer comprising an electrode active material, a solid electrolyte, and a binder material is formed on the aforementioned current collector.

[0161] The electrode active material, solid electrolyte, and binder material included in the electrode composite material layer of the electrode are not particularly limited, and known electrode active materials, solid electrolytes, and binders can be used. Furthermore, the electrode composite material layer in the electrode may also be a solid electrolyte-containing layer according to the present invention.

[0162] <Methods for forming solid electrolyte layers>

[0163] The following methods can be cited as specific ways to form a solid electrolyte layer.

[0164] 1) A method of applying the slurry composition of the present invention to the surface of the current collector or the electrode (in the case of the electrode, the surface on the side of the electrode composite layer, the same below), and then drying it;

[0165] 2) A method for drying a current collector or electrode after immersing it in the slurry composition of the present invention; and

[0166] 3) A method of applying the slurry composition of the present invention onto a release substrate and drying it to produce a solid electrolyte layer, and transferring the obtained solid electrolyte layer onto the surface of an electrode.

[0167] Of these methods, the methods described in 1) and 3) above, which involve coating and drying, are particularly preferred because the thickness of the layer containing the solid electrolyte layer can be easily controlled.

[0168] <<Apply>>

[0169] There are no particular limitations on the method of applying the slurry composition to the substrate, and examples include, for instance, doctor blade method, reverse roller method, direct roller method, gravure printing method, extrusion method, brush coating method, etc.

[0170] <<Drying>>

[0171] There are no particular limitations on the method for drying the slurry composition on the substrate, and known methods can be used. Examples of drying methods include drying methods using warm air, hot air, or low-humidity air, vacuum drying methods, and drying methods using infrared rays, electron beams, etc.

[0172] Furthermore, when the electrode composite layer contains a solid electrolyte layer, it can be pressed using methods such as rolling after drying. This pressing process allows for further increases in the density of the resulting electrode composite layer.

[0173] <<Transfer>>

[0174] In the method described in 3) above, there are no particular limitations on the method of transferring the solid electrolyte layer onto the surface of the electrode or the like, and known transfer methods can be used.

[0175] (electrode)

[0176] Furthermore, the electrode formed by forming an electrode composite layer on a current collector using the slurry composition for all-solid-state secondary batteries of the present invention contains at least a solid electrolyte, an electrode active material, and a polymer in the electrode composite layer, which enables the all-solid-state secondary battery to exhibit excellent battery cell characteristics (cycle characteristics, etc.).

[0177] (Solid electrolyte layer)

[0178] Furthermore, the solid electrolyte layer formed using the all-solid-state secondary battery slurry composition of the present invention contains at least a solid electrolyte and a polymer, enabling the all-solid-state secondary battery to exhibit excellent cell characteristics (cycle characteristics, etc.).

[0179] (All-solid-state rechargeable battery)

[0180] The all-solid-state secondary battery of the present invention has the solid electrolyte layer of the present invention as described above. Here, the all-solid-state secondary battery of the present invention has, for example, a positive electrode, a solid electrolyte layer, and a negative electrode, wherein at least one of the positive electrode composite material layer of the positive electrode, the negative electrode composite material layer of the negative electrode, and the solid electrolyte layer is the solid electrolyte layer of the present invention. That is, the all-solid-state secondary battery of the present invention has at least one of the following: a positive electrode having a positive electrode composite material layer formed using a slurry composition for a positive electrode composite material layer of the all-solid-state secondary battery of the present invention; a negative electrode having a negative electrode composite material layer formed using a slurry composition for a negative electrode composite material layer of the all-solid-state secondary battery of the present invention; and a solid electrolyte layer formed using a slurry composition for a solid electrolyte layer of the all-solid-state secondary battery of the present invention.

[0181] Furthermore, the all-solid-state secondary battery of the present invention has excellent battery cell characteristics such as cycle characteristics because it has the solid electrolyte layer of the present invention.

[0182] Furthermore, from the viewpoint of further improving battery cell characteristics such as cycle characteristics, the all-solid-state secondary battery of the present invention preferably has a positive electrode composite material layer of the positive electrode, a negative electrode composite material layer of the negative electrode, and a solid electrolyte layer, all of which are solid electrolyte layers of the present invention.

[0183] Here, as an electrode for an all-solid-state secondary battery that has an electrode composite material layer containing a solid electrolyte layer, which is not part of the present invention, there is no particular limitation as long as it is an electrode composite material layer containing a solid electrolyte layer, which is not part of the present invention, and any all-solid-state secondary battery electrode can be used.

[0184] Furthermore, there are no particular limitations on the solid electrolyte layer containing the solid electrolyte layer that is not part of the present invention and can be used in the all-solid-state secondary battery of the present invention. Any solid electrolyte layer, such as those described in Japanese Patent Application Publication No. 2012-243476, Japanese Patent Application Publication No. 2013-143299, and Japanese Patent Application Publication No. 2016-143614, can be used.

[0185] Furthermore, the all-solid-state secondary battery of the present invention can be obtained by stacking the positive and negative electrodes with the positive electrode composite material layer of the positive electrode and the negative electrode composite material layer facing each other through a solid electrolyte layer, applying pressure arbitrarily to obtain the laminate, and then, depending on the shape of the battery, placing it in its original state or by winding, folding, etc., into a battery container and sealing it. Additionally, if necessary, porous metal mesh, fuses, PTC elements, or other overcurrent protection components, conductive plates, etc., can be inserted into the battery container to prevent pressure rise and overcharging / discharging of the battery. The battery shape can be any of the following: coin-shaped, button-shaped, sheet-shaped, cylindrical, square, flat, etc.

[0186] Example

[0187] The present invention will now be described in detail based on embodiments, but the present invention is not limited to these embodiments. Furthermore, in the following description, unless otherwise specified, "%", "parts", and "ppm" are used to indicate quantities based on mass.

[0188] Furthermore, in the examples and comparative examples, the molecular weight (weight-average molecular weight, molecular weight distribution) and iodine value of the polymer, the metal content of the binder composition, the number-average particle size of the solid electrolyte, the dispersibility of the slurry composition, the adhesiveness of the solid electrolyte layer, and the output characteristics, cycle characteristics and IV resistance of the all-solid-state secondary battery were determined or evaluated by the following methods.

[0189] <Molecular weight of polymer>

[0190] Using a 10 mM LiBr-DMF solution, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polymer were determined by gel permeation chromatography (GPC) under the following test conditions, and the molecular weight distribution (Mw / Mn) was calculated.

[0191] • Separation column: Shodex KD-806M (manufactured by Showa Denko Co., Ltd.)

[0192] • Detector: Differential refractometer detector RID-10A (manufactured by Shimadzu Corporation)

[0193] • Flow rate of eluent: 0.3 mL / min

[0194] Column temperature: 40℃

[0195] • Standard polymer: TSK standard polystyrene (manufactured by Tosoh Corporation)

[0196] <Iodine value of polymer>

[0197] The obtained polymer was vacuum dried at 60°C for 24 hours, and the iodine value was determined according to JIS K6235 (2006).

[0198] <Metal content of the adhesive composition>

[0199] Approximately 1 g of the binder composition was ashed in an electric furnace at 550°C for about 3 hours. Then, approximately 5 mL of concentrated sulfuric acid was added to the ashed binder composition to dissolve it, followed by the slow addition of approximately 5 mL of concentrated nitric acid for wet decomposition. After decomposition, the acid was concentrated and brought to a final volume of 10 mL with ultrapure water. The content of each metal in the binder composition (relative to the amount of polymer) was determined using an ICP-AES apparatus (manufactured by Seiko Nanotechnology Co., Ltd., model "SPS-5100").

[0200] <Number-average particle size of solid electrolytes>

[0201] According to JIS Z8825-1:2001, the number-average particle size of solid electrolytes was determined by a laser ablation apparatus (Shimadzu Corporation, laser diffraction particle size distribution measuring device "SALD-3100").

[0202] <Dispersibility of the slurry composition>

[0203] The viscosity of slurry compositions for all-solid-state secondary batteries (slurry compositions for electrode composite layers and slurry compositions for solid electrolyte layers) was determined using a Brookfield Type B viscometer at 60 rpm (25°C) and evaluated according to the following criteria. The lower the viscosity of the same slurry composition at the same solid component concentration, the better the dispersion of solid components such as solid electrolytes in the slurry composition.

[0204] A: Viscosity less than 3000 mPa·s

[0205] B: Viscosity above 3000 mPa·s and below 5000 mPa·s

[0206] C: Viscosity above 5000 mPa·s and below 8000 mPa·s

[0207] D: Viscosity above 8000 mPa·s or non-dispersible (no flowability)

[0208] <Adhesion of solid electrolyte layer>

[0209] <<Positive Electrode Composite Material Layer>>

[0210] The positive electrode was cut into rectangles 1.0 cm wide and 10 cm long to serve as test pieces. After attaching cellophane tape (as specified in JIS Z 1522) to the surface of the positive electrode composite layer of the test piece, the transparent tape was peeled off from one end of the test piece in a 180° direction at a speed of 50 mm / min, and the stress during peeling was measured. A total of 3 measurements were performed, and the average value was calculated as the peel strength (N / m), which was evaluated according to the following criteria. The greater the peel strength, the better the adhesion of the positive electrode composite layer and the stronger the bond with the current collector.

[0211] A: Peel strength is above 3N / m

[0212] B: Peel strength is above 2N / m and less than 3N / m

[0213] C: Peel strength is above 1N / m and less than 2N / m

[0214] D: Peel strength less than 1 N / m

[0215] <<Negative Electrode Composite Material Layer>>

[0216] The negative electrode was cut into rectangles 1.0 cm wide and 10 cm long to serve as test pieces. After attaching cellophane tape (as specified in JIS Z 1522) to the surface of the negative electrode composite layer of the test piece, the transparent tape was peeled off from one end of the test piece in a 180° direction at a speed of 50 mm / min, and the stress during peeling was measured. A total of 3 measurements were performed, and the average value was calculated as the peel strength (N / m), which was evaluated according to the following criteria. The greater the peel strength, the better the adhesion of the negative electrode composite layer and the stronger the bond with the current collector.

[0217] A: Peel strength is above 4 N / m

[0218] B: Peel strength is above 3N / m and below 4N / m

[0219] C: Peel strength is above 2N / m and less than 3N / m

[0220] D: Peel strength less than 2N / m

[0221] <Output Characteristics of All-Solid-State Secondary Batteries>

[0222] A three-cell all-solid-state secondary battery was charged to 4.2V using a 0.1C constant current method, and then discharged to 3.0V at 0.1C. The 0.1C discharge capacity was calculated. Next, it was charged to 4.2V at 0.1C, and then discharged to 3.0V at 2C. The 2C discharge capacity was calculated. The average 0.1C discharge capacity of the three cells was defined as discharge capacity *a*, and the average 2C discharge capacity of the three cells was defined as discharge capacity *b*. The ratio of discharge capacity *b* to discharge capacity *a* (capacity ratio) was calculated as: discharge capacity *b* / discharge capacity *a* × 100 (%). The following criteria were used for evaluation: A higher capacity ratio indicates better output characteristics of the all-solid-state secondary battery.

[0223] A: Capacity ratio is above 80%

[0224] B: Capacity ratio is above 70% and below 80%.

[0225] C: Capacity ratio is above 50% and below 70%.

[0226] D: Capacity ratio less than 50%

[0227] <Cycling characteristics of all-solid-state secondary batteries>

[0228] The all-solid-state secondary battery was charged at 0.2C from 3V to 4.2V at 25°C, and then discharged at 0.2C from 4.2V to 3V. This charge-discharge cycle was repeated 50 times. The percentage ratio of the 0.2C discharge capacity of the 50th cycle to the 0.2C discharge capacity of the 1st cycle was calculated. This calculated value was used as the capacity retention rate, and evaluated according to the following criteria. A higher capacity retention rate indicates less capacity loss during discharge, and better cycle characteristics of the all-solid-state secondary battery.

[0229] A: Capacity retention rate is over 90%.

[0230] B: Capacity retention rate is above 80% and below 90%.

[0231] C: Capacity retention rate is above 70% and below 80%.

[0232] D: Capacity retention rate less than 70%

[0233] <IV Resistor of All-Solid-State Secondary Battery>

[0234] The all-solid-state battery was charged to 50% SOC (State of Charge) at 25°C using a 1C rate (C is expressed as rated capacity (mA) / 1h). Then, using 50% SOC as the center, it was charged and discharged for 30 seconds at 0.1C, 0.2C, 0.5C, 1C, and 2C rates, respectively. The battery voltage after 10 seconds of discharge was plotted against the current, and the slope was calculated as the IV resistance (Ω) (IV resistance during charging and IV resistance during discharging). The obtained IV resistance value (Ω) was evaluated according to the following criteria: a smaller IV resistance value indicates a smaller internal resistance.

[0235] A: IV resistance is less than 80Ω

[0236] B: IV resistance is 80Ω or higher and less than 90Ω

[0237] C: IV resistance is 90Ω or higher and less than 100Ω

[0238] D: IV resistance is 100Ω or higher

[0239] (Example 1)

[0240] <Preparation of Adhesive Compositions>

[0241] In a reactor, 180 parts of deionized water, 25 parts of a 10% sodium dodecylbenzenesulfonate aqueous solution (as emulsifier), 25 parts of acrylonitrile (as a nitrile monomer), 30 parts of n-butyl acrylate (as a (meth)acrylate monomer), and 0.3 parts of tert-dodecyl mercaptan (as a molecular weight regulator) were added sequentially. After purging the reactor gas three times with nitrogen, 45 parts of 1,3-butadiene (as a diene monomer) were added. In a reactor maintained at 10°C, 0.1 parts of cumene peroxide (as a polymerization initiator) and 0.1 parts of ferrous sulfate were added to initiate the polymerization reaction, which was carried out with stirring. When the polymerization conversion reached 90%, 0.2 parts of hydroxylamine sulfate were added relative to 100 parts of monomer to terminate the polymerization. Then, residual monomer was removed under reduced pressure at 80°C to obtain an aqueous dispersion of the polymer precursor (nitrile rubber). Then, relative to 100 parts of the polymer precursor solids in the obtained particulate aqueous dispersion, 12 parts of an aqueous solution of calcium chloride (coagulant) were added, and the mixture was stirred to coagulate the latex. Then, the latex was filtered while being washed with water, and the resulting coagulated material was vacuum dried at 60°C for 12 hours to obtain the polymer precursor (nitrile rubber).

[0242] Next, the above polymer precursor was hydrogenated using an oil-layer hydrogenation method. The polymer precursor was dissolved in acetone to obtain an acetone solution with a polymer precursor concentration of 12%. This acetone solution was added to an autoclave, and a palladium-silica catalyst at a mass ratio of 200 ppm relative to the polymer precursor was added. The hydrogenation reaction was carried out at a hydrogen pressure of 3.0 MPa for 6 hours. The palladium-silica catalyst was filtered off from the obtained reactants, and the acetone solvent was removed under reduced pressure to obtain hydrogenated nitrile butadiene rubber as the target polymer. The molecular weight and iodine value of the hydrogenated nitrile butadiene rubber were determined. The results are shown in Table 1.

[0243] Next, an appropriate amount of butyl butyrate was added to the obtained hydrogenated nitrile butyrate rubber for dissolution. Then, 1,2-dichlorobenzene, as an aromatic halide, was added to the resulting polymer solution to make its amount relative to the hydrogenated nitrile butyrate rubber 50 ppm, yielding an adhesive composition (solids concentration: 8%). The metal content of the obtained adhesive composition was determined. The results are shown in Table 1.

[0244] <Preparation of Slurry Composition for Positive Electrode Composite Layer>

[0245] 5.0 parts of carbon nanotubes (specific surface area: 230 m²) were added as a conductive material. 2The above-mentioned binder composition, including 1.0 parts (converted to solid content) of butyl butyrate and 1.0 parts (converted to solid content), was stirred using a disperser (3000 rpm, 10 minutes) and then dispersed for 1 hour using a bead mill with zirconia beads of 1 mm diameter at a circumferential speed of 8 m / s, thereby preparing a conductive material dispersion with a solid content concentration of 6.0%.

[0246] A slurry composition for a positive electrode composite layer was prepared by mixing 70 parts of lithium cobalt oxide (number average particle size: 11.5 μm) as the positive electrode active material, 26 parts of a sulfide glass composed of Li₂S and P₂S₅ (Li₂S / P₂S₅ = 70 mol% / 30 mol%, number average particle size: 0.8 μm) as the solid electrolyte, 2.4 parts (equivalent to solid content) of the above-mentioned conductive material dispersion, and 1.6 parts (equivalent to solid content) of the above-mentioned binder composition. Butyl butyrate was then added to adjust the solid content concentration to 80%, and the mixture was stirred using a planetary mixer for 60 minutes. Xylene was then added to adjust the solid content concentration to 65%, and the mixture was stirred for 10 minutes. The dispersibility of this slurry composition for a positive electrode composite layer was evaluated. The results are shown in Table 1.

[0247] <Preparation of Slurry Composition for Negative Electrode Composite Layer>

[0248] 5.0 parts of carbon nanotubes (specific surface area: 230 m²) were added as a conductive material. 2 The above binder composition (converted to solid content) and 1.0 parts of butyrate were mixed in a disperser (3000 rpm, 10 minutes) and then dispersed at a speed of 8 m / s for 1 hour using a bead mill with 1 mm diameter zirconia beads to prepare a conductive material dispersion with a solid content concentration of 6.0%.

[0249] A slurry composition for a negative electrode composite layer was prepared by mixing 60 parts of graphite (number average particle size: 20 μm) as the negative electrode active material, 36.5 parts of a sulfide glass composed of Li₂S and P₂S₅ (Li₂S / P₂S₅ = 70 mol% / 30 mol%, number average particle size: 0.8 μm) as the solid electrolyte, 1.8 parts (equivalent to solid content) of the above-mentioned conductive material dispersion, and 2.2 parts (equivalent to solid content) of the above-mentioned binder composition. Butyl butyrate was then added to adjust the solid content concentration to 65%, and the mixture was stirred using a planetary mixer for 60 minutes. Then, butyl butyrate was added again to adjust the solid content concentration to 60%, and the mixture was stirred using a planetary mixer. The dispersibility of this slurry composition for a negative electrode composite layer was evaluated. The results are shown in Table 1.

[0250] <Preparation of slurry compositions for solid electrolyte layers>

[0251] In a glove box under argon atmosphere (moisture concentration 0.6 ppm, oxygen concentration 1.8 ppm), 100 parts of a sulfide glass composed of Li₂S and P₂S₅ (Li₂S / P₂S₅ = 70 mol% / 30 mol%, number average particle size: 0.8 μm) as a solid electrolyte and 2 parts (equivalent amount of solid component) of the above-mentioned binder composition were mixed. Butyl butyrate was then added to adjust the solid component concentration to 65% by mass, and the mixture was stirred for 60 minutes using a planetary mixer. Then, butyl butyrate was added again to adjust the solid component concentration to 55%, and the mixture was stirred again using a planetary mixer to prepare a slurry composition for the solid electrolyte layer. The dispersibility of the slurry composition for the solid electrolyte layer was evaluated. The results are shown in Table 1.

[0252] <The Making of Positive Electrode>

[0253] The above-mentioned slurry composition for the positive electrode composite layer was coated onto the surface of the current collector (aluminum foil, thickness: 20 μm) and dried (at 120°C for 60 minutes) to form a positive electrode composite layer with a thickness of 50 μm, thus obtaining the positive electrode. The adhesion of the positive electrode composite layer was evaluated using this positive electrode. The results are shown in Table 1.

[0254] <Making the Negative Electrode>

[0255] The above-mentioned slurry composition for the negative electrode composite layer was coated onto the surface of the current collector (copper foil, thickness: 15 μm) and dried (at 120°C for 60 minutes) to form a negative electrode composite layer with a thickness of 60 μm, thus obtaining the negative electrode. The adhesion of the negative electrode composite layer was evaluated using this negative electrode. The results are shown in Table 1.

[0256] <Manufacturing of All-Solid-State Secondary Batteries>

[0257] Next, the above-mentioned slurry composition for the solid electrolyte layer is coated onto the imide film (thickness: 25 μm) and dried (at 120°C for 60 minutes) to form a solid electrolyte layer (containing the solid electrolyte layer) with a thickness of 150 μm. The solid electrolyte layer on the imide film and the positive electrode are bonded together in a manner that the solid electrolyte layer is attached to the positive electrode composite material layer. The solid electrolyte layer is transferred from the imide film to the positive electrode composite material layer by applying a pressure of 400 MPa (pressing pressure), thereby obtaining a positive electrode with a solid electrolyte layer.

[0258] The aforementioned positive and negative electrodes with solid electrolyte layers were bonded together by attaching the solid electrolyte layer of the positive electrode to the negative electrode composite material layer. A pressing process was then performed by applying a pressure of 400 MPa (compression pressure) to the solid electrolyte layer of the positive electrode to obtain an all-solid-state secondary battery. The thickness of the solid electrolyte layer in the pressed all-solid-state secondary battery was 120 μm. The output characteristics, cycle characteristics, and IV resistance of this all-solid-state secondary battery were evaluated. The results are shown in Table 1.

[0259] (Examples 2 and 3)

[0260] In preparing the binder composition, 1,2-dichlorobenzene, as an aromatic halide, was added at amounts of 2000 ppm (Example 2) and 7 ppm (Example 3) relative to the amount of hydrogenated nitrile rubber. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 1.

[0261] (Examples 4 and 5)

[0262] In preparing the binder composition, 2-ethylhexyl acrylate (Example 4) and cyclohexyl acrylate (Example 5) were used instead of n-butyl acrylate as the (meth)acrylate monomer. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 1.

[0263] (Examples 6-9)

[0264] In preparing the binder composition, the amounts of acrylonitrile (AN), n-butyl acrylate (BA), and 1,3-butadiene (BD) were changed to the amounts shown below. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 1.

[0265] Example 6: 29 parts AN, 25 parts BA, and 46 parts BD

[0266] Example 7: 10 parts AN, 35 parts BA, and 55 parts BD

[0267] Example 8: 25 parts of AN, 38 parts of BA, and 37 parts of BD

[0268] Example 9: 25 parts AN, 18 parts BA, and 57 parts BD

[0269] (Example 10)

[0270] In preparing the slurry compositions for the positive electrode composite layer and the negative electrode composite layer, carbon black (DENKABLACK (registered trademark)) was used instead of carbon nanotubes. Otherwise, the binder composition, the slurry composition for the positive electrode composite layer, the slurry composition for the negative electrode composite layer, the slurry composition for the solid electrolyte layer, the positive electrode, the negative electrode, and an all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 2.

[0271] (Example 11)

[0272] Using the binder composition prepared below, except that slurry compositions for positive electrode composite layers, negative electrode composite layers, solid electrolyte layers, positive electrodes, negative electrodes, and all-solid-state secondary batteries were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 2.

[0273] <Preparation of Adhesive Compositions>

[0274] The polymer precursor (nitrile rubber) was obtained in the same manner as in Example 1. The metathesis of this polymer precursor was carried out as follows.

[0275] The polymer precursor was dissolved in 141 parts of monochlorobenzene and added to a reactor. The reactor was then heated to 80°C, and 2 L of a monochlorobenzene solution containing bis(tricyclohexylphosphine)benzylmethylene ruthenium dichloride was added as a Grubbs catalyst, with the amount of Grubbs catalyst being 0.25 parts per 100 parts of polymer precursor. The reactor was then pressurized to 3.5 MPa with ethylene as the copolyolefin, and the metathesis reaction of the polymer was carried out with stirring at 600 rpm. During the reaction, a cooling coil connected to a temperature control device and a thermal sensor was used to maintain a constant temperature.

[0276] Next, hydrogenation is carried out as follows.

[0277] Following the aforementioned metathesis reaction, the reactor was degassed three times with H₂ at 0.7 MPa while stirring. Then, the reactor temperature was raised to 130°C, and 1 L of a monochlorobenzene solution containing Wilkinson catalyst and triphenylphosphine was added. The amount of Wilkinson catalyst was 0.075 parts and the amount of triphenylphosphine was 1 part per 100 parts of polymer. The temperature was then raised to 138°C, and the polymer was hydrogenated at a hydrogen pressure (gauge pressure) of 8.4 MPa, ending the reaction at an iodine value of 1.3 mg / 100 mg. After the reaction, 0.2 parts of activated carbon with an average diameter of 15 μm were added to the reactor, and the mixture was stirred for 30 minutes. The solution was then filtered through a 5 μm filter. Steam was then introduced into the filtrate, and monochlorobenzene was removed by steam distillation. The precipitated polymer (hydrogenated nitrile rubber) was separated, dried, and recovered.

[0278] Next, an appropriate amount of butyl butyrate was added to the obtained hydrogenated nitrile butyrate rubber to dissolve it, and 1,2-dichlorobenzene as an aromatic halide was added to the obtained polymer solution to make its amount relative to the hydrogenated nitrile butyrate rubber 50 ppm, to obtain an adhesive composition (solid component concentration: 8%).

[0279] (Example 12)

[0280] In preparing the binder composition, the amount of palladium-silica catalyst relative to the amount of polymer precursor was changed to 450 ppm by mass. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 2.

[0281] (Example 13)

[0282] In preparing the binder composition, an aqueous solution of sodium hydroxide was added to the aqueous dispersion of the polymer precursor (nitrile rubber) before solidification, and the amount of calcium chloride used as a coagulant was increased. Otherwise, the binder composition, the slurry composition for the positive electrode composite layer, the slurry composition for the negative electrode composite layer, the slurry composition for the solid electrolyte layer, the positive electrode, the negative electrode, and the all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 2.

[0283] (Example 14)

[0284] In preparing the binder composition, the hydrogen pressure and reaction time during hydrogenation were varied to obtain a polymer with an iodine value of 1.5 mg / 100 mg. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 2.

[0285] (Examples 15 and 16)

[0286] In preparing the binder composition, ethyl acrylate (Example 15) and methyl methacrylate (Example 16) were used instead of n-butyl acrylate as the (meth)acrylate monomer, respectively. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 2.

[0287] (Examples 17-19, 23)

[0288] In preparing the binder composition, the slurry composition for the positive electrode composite layer, the slurry composition for the negative electrode composite layer, and the slurry composition for the solid electrolyte layer, cyclopentyl methyl ether (Example 17), xylene (Example 18), diisobutyl ketone (Example 19), and isobutyl isobutyrate (Example 23) were used instead of butyl butyrate, respectively. Otherwise, the binder composition, the slurry composition for the positive electrode composite layer, the slurry composition for the negative electrode composite layer, the slurry composition for the solid electrolyte layer, the positive electrode, the negative electrode, and an all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 2 or 3.

[0289] (Example 20)

[0290] In preparing the binder composition, the amount of tert-dodecyl mercaptan was changed to 6 parts. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 3.

[0291] (Example 21)

[0292] In preparing the slurry compositions for the negative electrode composite layer and the solid electrolyte layer, a binder composition containing polyvinylidene fluoride was used instead of a binder composition containing hydrogenated nitrile butadiene rubber. Otherwise, the binder compositions, slurry compositions for the positive electrode composite layer, slurry compositions for the negative electrode composite layer, slurry compositions for the solid electrolyte layer, positive electrodes, negative electrodes, and all-solid-state secondary batteries were prepared in the same manner as in Example 1. Various evaluations were conducted, except for the dispersibility of the slurry compositions for the negative electrode composite layer and the solid electrolyte layer, and the adhesion of the negative electrode composite layer. The results are shown in Table 3.

[0293] (Example 22)

[0294] In preparing the binder composition, 1,2,4-trichlorobenzene was used instead of 1,2-dichlorobenzene as the aromatic halide. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 3.

[0295] (Example 24)

[0296] In preparing the slurry composition for the positive electrode composite layer and the slurry composition for the negative electrode composite layer, a specific surface area of ​​150 m² is used. 2 / g of carbon nanotubes replaces a specific surface area of ​​230m² 2 / g carbon nanotubes were used as the conductive material. In addition, in the same manner as in Example 1, a binder composition, a slurry composition for the positive electrode composite layer, a slurry composition for the negative electrode composite layer, a slurry composition for the solid electrolyte layer, a positive electrode, a negative electrode, and an all-solid-state secondary battery were prepared, and various evaluations were carried out. The results are shown in Table 3.

[0297] (Comparative Examples 1-2)

[0298] In preparing the binder composition, the amounts of acrylonitrile (AN), n-butyl acrylate (BA), and 1,3-butadiene (BD) were changed to the amounts shown below. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 4.

[0299] Comparative Example 1: 25 portions of AN, 0 portions of BA, and 75 portions of BD

[0300] Comparative Example 2: 0 portions of AN, 30 portions of BA, and 70 portions of BD

[0301] (Comparative Example 3)

[0302] In preparing the binder composition, 1,2-dichlorobenzene, as an aromatic halide, was not used. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 4.

[0303] (Comparative Example 4)

[0304] In preparing the binder composition, 1,2-dichlorobenzene, as an aromatic halide, was added at a concentration of 5000 ppm relative to the hydrogenated nitrile rubber. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 4.

[0305] (Comparative Example 5)

[0306] In preparing the binder composition, monochlorobenzene was used instead of 1,2-dichlorobenzene as the aromatic halide, and was added at a rate of 200 ppm relative to the amount of hydrogenated nitrile rubber. Otherwise, the binder composition, slurry composition for the positive electrode composite layer, slurry composition for the negative electrode composite layer, slurry composition for the solid electrolyte layer, positive electrode, negative electrode, and all-solid-state secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 4.

[0307] In addition, in Tables 1 to 4 shown below,

[0308] "Nitrile group" indicates a monomer unit containing a nitrile group.

[0309] "(Meth)acrylate" represents the (meth)acrylate monomer unit.

[0310] “Diene” represents a diene monomer unit.

[0311] “AN” represents an acrylonitrile unit.

[0312] “BA” represents the n-butyl acrylate unit.

[0313] “EHA” represents the 2-ethylhexyl acrylate unit.

[0314] "CHA" indicates cyclohexyl acrylate unit.

[0315] “EA” represents the ethyl acrylate unit.

[0316] “MMA” represents methyl methacrylate unit.

[0317] "H-BD" represents a 1,3-butadiene hydride unit,

[0318] "Mw / Mn" represents the molecular weight distribution,

[0319] "Mw" represents the weight-average molecular weight distribution,

[0320] "DCB" represents 1,2-dichlorobenzene,

[0321] "TCB" represents 1,2,4-trichlorobenzene,

[0322] "CB" represents monochlorobenzene,

[0323] "Pd" represents palladium,

[0324] "Rh" represents rhodium,

[0325] "Ru" represents ruthenium,

[0326] "Na" represents sodium,

[0327] "Ca" represents calcium,

[0328] "DIK" represents diisobutyl ketone,

[0329] "XY" represents xylene,

[0330] "HB" represents butyl butyrate,

[0331] "IBIB" represents isobutyl isobutyrate,

[0332] "CPME" represents cyclopentyl methyl ether,

[0333] "CNT230" represents carbon nanotubes with a specific surface area of 230 m 2 / g, "CNT150" represents carbon nanotubes with a specific surface area of 150 m 2 / g, "DB" represents DENKABLACK,

[0334] "Positive" represents the positive electrode,

[0335] "Negative" represents the negative electrode,

[0336] "Solid state" represents the solid electrolyte layer.

[0337] [Table 1]

[0338]

[0339] [Table 2]

[0340]

[0341] [Table 3]

[0342]

[0343] [Table 4]

[0344]

[0345] As shown in Tables 1-3, the binder compositions of Examples 1-24 can prepare slurry compositions with excellent dispersibility and enable all-solid-state secondary batteries to exhibit excellent cycle characteristics. Furthermore, the binder compositions of Examples 1-24 can form a solid electrolyte layer with excellent adhesion, reduce the IV resistance of the all-solid-state secondary battery, and improve output characteristics.

[0346] On the other hand, as shown in Table 4, in Comparative Example 1, which used a binder composition containing a polymer without (meth)acrylate monomer units, and in Comparative Example 2, which used a binder composition containing a polymer without nitrile monomer units, the dispersibility of the slurry composition, the adhesion of the solid electrolyte layer, and the cell characteristics of the all-solid-state secondary battery were reduced.

[0347] Furthermore, as shown in Table 4, in Comparative Example 3, which used a binder composition that did not contain the specified aromatic halides, and in Comparative Example 4, which used a binder composition in which the amount of the specified aromatic halides exceeded the specified upper limit, the dispersibility of the slurry composition, the adhesion of the solid electrolyte layer, and the cell characteristics of the all-solid-state secondary battery were reduced.

[0348] Furthermore, as shown in Table 4, in Comparative Example 5, which uses monochlorobenzene instead of the specified aromatic halides, the dispersibility of the slurry composition, the adhesion of the solid electrolyte layer, and the cell characteristics of the all-solid-state secondary battery are reduced.

[0349] Industrial availability

[0350] According to the present invention, a binder composition for all-solid-state secondary batteries can be provided, which can prepare a slurry composition for all-solid-state secondary batteries with excellent dispersibility, and can form a solid electrolyte layer that enables all-solid-state secondary batteries to exhibit excellent cycle characteristics.

[0351] Furthermore, according to the present invention, a slurry composition for all-solid-state secondary batteries can be provided, which has excellent dispersibility and can form a solid electrolyte layer that enables all-solid-state secondary batteries to exhibit excellent cycle characteristics.

[0352] Furthermore, according to the present invention, it is possible to provide a solid electrolyte layer containing a solid electrolyte layer that enables an all-solid-state secondary battery to exhibit excellent cycle characteristics, and an all-solid-state secondary battery with excellent cycle characteristics.

Claims

1. A binder composition for all-solid-state secondary batteries, comprising a polymer and an aromatic halide, The polymer contains nitrile monomer units in a proportion of 10% to 35% by mass and (meth)acrylate monomer units in a proportion of 15% to 40% by mass. The polymer also contains diene monomer units. The aromatic halide has a structure in which two or more but no more than four halogen atoms are directly bonded to the aromatic ring, and The content of the aromatic halide is 5 ppm by mass or more and 3000 ppm by mass relative to the content of the polymer.

2. The binder composition for all-solid-state secondary batteries according to claim 1, wherein, The binder composition for all-solid-state secondary batteries contains a metal belonging to the 5th period and groups 3 to 14 of the periodic table in an amount of 0.5 ppm by mass or more and 200 ppm by mass or less relative to the polymer.

3. The binder composition for all-solid-state secondary batteries according to claim 1 or 2, wherein, The binder composition for all-solid-state secondary batteries contains a metal belonging to Group 1 or Group 2 of the periodic table in an amount of 5 ppm by mass or more and 3000 ppm by mass relative to the polymer.

4. The binder composition for all-solid-state secondary batteries according to claim 1 or 2, wherein, The iodine value of the polymer, as determined by JIS K6235 (2006), is greater than 0.5 mg / 100 mg and less than 20 mg / 100 mg.

5. The binder composition for all-solid-state secondary batteries according to claim 1 or 2, wherein, The alkyl group constituting the non-carbonyl oxygen atom of the (meth)acrylate monomer unit has 4 or more and 9 or fewer carbon atoms.

6. The binder composition for all-solid-state secondary batteries according to claim 1 or 2, wherein, The binder composition for all-solid-state secondary batteries also contains a solvent.

7. A slurry composition for an all-solid-state secondary battery, comprising a solid electrolyte and the binder composition for an all-solid-state secondary battery as described in claim 6.

8. The slurry composition for all-solid-state secondary batteries according to claim 7, wherein, The slurry composition for all-solid-state secondary batteries also contains electrode active materials.

9. The slurry composition for all-solid-state secondary batteries according to claim 8, wherein, The slurry composition for all-solid-state secondary batteries also contains carbon nanotubes.

10. A solid electrolyte layer formed using any one of the all-solid-state secondary battery slurry compositions according to claims 7 to 9.

11. An all-solid-state secondary battery having the solid electrolyte layer as described in claim 10.

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