Electrode material, method for manufacturing electrode material, and battery

Abstract

An electrode material according to one aspect of the present disclosure comprises an active material, electrically conductive fibers including a carbon material, and a binder including an elastomer. The elastomer is a hydrogenated product and includes a repeating unit having an aromatic ring. The contained percentage of the repeating unit in the elastomer is 15 mass% or more.

Description

[[Technical Field]]

[0001] The present disclosure relates to an electrode material, a method for producing an electrode material, and a battery. [[Background Art]]

[0002] A conductive auxiliary agent is usually added to an active material layer of an electrode for the purpose of improving electron conductivity in the active material layer and improving the cycle characteristics of a battery. The active material layer is formed from, for example, an electrode material containing an active material and a conductive auxiliary agent. Patent Documents 1 and 2 disclose electrode materials containing a carbon material as a conductive auxiliary agent. [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Publication No. 2011-134675 [[Patent Document 2]] Japanese Unexamined Patent Publication No. 2020-145034 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] An object of the present disclosure is to provide an electrode material suitable for producing an electrode with improved electron conductivity. [[Means for Solving the Problem]]

[0005] The electrode material according to one aspect of the present disclosure is an active material, conductive fibers containing a carbon material, a binder containing an elastomer, comprising the elastomer is a hydrogenated product and contains a repeating unit having an aromatic ring, the content of the repeating unit in the elastomer is 15% by mass or more. [[Effect of the Invention]]

[0006] This disclosure provides an electrode material suitable for fabricating electrodes with improved electronic conductivity. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram of the electrode material according to Embodiment 1. [Figure 2] Figure 2 shows an example of an elastomer. [Figure 3] Figure 3 is a flowchart showing an example of a method for manufacturing electrode materials. [Figure 4] Figure 4 is a flowchart showing another example of a method for manufacturing electrode materials. [Figure 5] Figure 5 is a flowchart showing another example of a method for manufacturing electrode materials. [Figure 6] Figure 6 is a flowchart showing another example of a method for manufacturing electrode materials. [Figure 7] Figure 7 is a flowchart showing another example of a method for manufacturing electrode materials. [Figure 8] Figure 8 is a cross-sectional view of the battery according to Embodiment 2. [Figure 9] Figure 9 is a flowchart showing the method for manufacturing the electrode material of Comparative Example 4. [Modes for carrying out the invention]

[0008] (Knowledge that forms the basis of this disclosure) In the field of conventional secondary batteries, organic electrolytes obtained by dissolving electrolyte salts in organic solvents are mainly used. However, secondary batteries using organic electrolytes raise concerns about leakage. It has also been pointed out that they generate a large amount of heat in the event of a short circuit or other malfunction.

[0009] On the other hand, all-solid-state rechargeable batteries, which use inorganic solid electrolytes instead of organic electrolytes, are attracting attention. All-solid-state rechargeable batteries do not leak. Because inorganic solid electrolytes have high thermal stability, it is expected that heat generation in the event of a short circuit or other malfunction will also be suppressed.

[0010] In all-solid-state secondary batteries, electrodes tend to expand or contract during charging and discharging. This expansion or contraction is particularly pronounced when the electrode is the negative electrode. According to the inventors' research, conductive fibers such as carbon nanotubes (CNTs) can easily maintain percolation within the electrode even when expansion or contraction occurs. Therefore, conductive fibers are suitable as conductive additives to improve the conductivity of electrodes.

[0011] However, conductive fibers such as CNTs tend to aggregate easily. Therefore, to ensure the desired conductivity of the electrode, it is necessary to either increase the amount of conductive fibers added to the electrode material or add a dispersant to the electrode material. However, increasing the amount of conductive fibers tends to reduce the battery's energy density and ionic conductivity within the electrode, thus degrading the battery's performance. When a dispersant is added to the electrode material, the polar groups contained in the dispersant react with the solid electrolyte, which can degrade the battery's performance. Furthermore, dispersants tend to reduce the adhesion between the active material layer and the current collector in the electrode, and also tend to reduce the strength of the active material layer.

[0012] Patent Document 2 discloses a method for preparing electrode materials by adding a solid electrolyte and an active material to a slurry containing a conductive additive. However, with this method, it is difficult to uniformly disperse the conductive additive in the electrode material when conductive fibers are used as the conductive additive. Patent Document 2 neither describes nor suggests any method for improving the dispersibility of conductive fibers.

[0013] As a result of diligent research, the inventors have newly discovered that the dispersibility of conductive fibers in the electrode material changes by using a specific binder instead of a dispersant. Based on this newly discovered finding, the inventors proceeded with their research and found that by combining a specific elastomer with conductive fibers, the dispersibility of conductive fibers in the electrode material is improved, and the electronic conductivity of electrodes formed from this electrode material is improved, leading to the completion of the electrode material of this disclosure.

[0014] (Summary of one aspect of this disclosure) The electrode material relating to the first aspect of this disclosure is Active material and, Conductive fibers containing carbon material, A binder containing elastomer, Includes, The elastomer is a hydrogenated material and contains repeating units having an aromatic ring. The content of the repeating units in the elastomer is 15% by mass or more.

[0015] According to the first embodiment, the binder tends to adsorb onto the conductive fibers due to the interaction between the aromatic ring contained in the elastomer and the carbon material contained in the conductive fibers. This interaction is, for example, a π-π interaction. By adsorbing the binder onto the conductive fibers, the binder can promote the dispersion of the conductive fibers in the electrode material. This improves the dispersibility of the conductive fibers in the electrode material. Such electrode materials are suitable for fabricating electrodes with improved electronic conductivity. In particular, desired electronic conductivity can be obtained for electrodes even when the amount of conductive fibers added is small.

[0016] In a second aspect of this disclosure, for example, in the electrode material according to the first aspect, the conductive fibers may include carbon nanotubes.

[0017] According to the second embodiment, the electrode material is suitable for fabricating electrodes with improved electronic conductivity.

[0018] In a third aspect of this disclosure, for example, in the electrode material according to the first or second aspect, the average fiber diameter of the conductive fibers may be 300 nm or less.

[0019] According to the third embodiment, because the average fiber diameter of the conductive fibers is small, the number of conductive fibers can be increased while maintaining the amount of conductive fibers added. Such conductive fibers have a significant effect in improving conductivity within the electrode. Normally, when the average fiber diameter of conductive fibers is small, the cohesive force of the conductive fibers increases and the dispersibility of the conductive fibers tends to decrease. However, depending on the binder contained in the electrode material, when the average fiber diameter of the conductive fibers is small, a significant effect of improving the dispersibility of the conductive fibers occurs.

[0020] In a fourth aspect of this disclosure, for example, in the electrode material according to any one of the first to third aspects, the elastomer may be a thermoplastic elastomer.

[0021] According to the fourth embodiment, the binder can efficiently disperse conductive fibers in the electrode material.

[0022] In a fifth aspect of this disclosure, for example, in an electrode material according to any one of the first to fourth aspects, the elastomer may have a first block comprising the repeating units having the aromatic ring and a second block comprising repeating units derived from a conjugated diene.

[0023] According to the fifth embodiment, the binder can efficiently disperse conductive fibers in the electrode material.

[0024] In a sixth aspect of this disclosure, for example, in an electrode material according to any one of the first to fifth aspects, the repeating unit having the aromatic ring may include repeating units derived from styrene.

[0025] According to the sixth embodiment, the binder can efficiently disperse conductive fibers in the electrode material.

[0026] In a seventh aspect of this disclosure, for example, in an electrode material according to any one of the first to sixth aspects, the elastomer may include at least one selected from the group consisting of styrene-ethylene / butylene-styrene block copolymer (SEBS) and styrene-ethylene / ethylene / propylene-styrene block copolymer (SEEPS).

[0027] According to the seventh embodiment, the binder can efficiently disperse conductive fibers in the electrode material.

[0028] In the eighth aspect of this disclosure, for example, in the electrode material according to any one of the first to seventh aspects, the hydrogenation rate of the elastomer may be 90% or more.

[0029] According to the eighth aspect, the degree of freedom of rotation of the molecular chains of the elastomer is improved. The binder containing this elastomer tends to be easily adsorbed by conductive fibers. Therefore, this binder significantly improves the dispersibility of the conductive fibers.

[0030] In the ninth aspect of this disclosure, for example, in the electrode material according to any one of the first to eighth aspects, the content of the repeating unit having the aromatic ring in the elastomer may be 20% by mass or more.

[0031] According to the ninth aspect, the elastomer contains a large amount of aromatic rings capable of interacting with the carbon material. Therefore, the binder containing this elastomer tends to be easily adsorbed by conductive fibers. This binder improves the effect of dispersing conductive fibers.

[0032] In the tenth aspect of this disclosure, for example, the electrode material according to any one of the first to ninth aspects may further include a solid electrolyte.

[0033] According to the tenth embodiment, the electrode material is suitable for fabricating electrodes for solid-state batteries.

[0034] In the eleventh aspect of this disclosure, for example, in the electrode material according to the tenth aspect, the solid electrolyte may have lithium ion conductivity.

[0035] According to the eleventh embodiment, electrodes formed from electrode material can increase the energy density of a lithium-ion battery containing a solid electrolyte and improve the battery's cycle characteristics.

[0036] In a twelfth aspect of this disclosure, for example, the electrode material according to any one of the first to eleventh aspects may further contain a solvent.

[0037] According to the twelfth embodiment, the binder can efficiently disperse conductive fibers in the electrode material.

[0038] A method for manufacturing an electrode material according to a 13th aspect of this disclosure is: A method for manufacturing an electrode material according to any one of the first to twelfth embodiments, The aforementioned manufacturing method is This includes preparing a slurry containing the conductive fibers and the binder.

[0039] According to the 13th embodiment, conductive fibers are dispersed in the slurry. Electrode materials prepared using this slurry tend to exhibit improved dispersibility of the conductive fibers. Electrodes formed from this electrode material also tend to easily form electron conduction paths between active materials. With this electrode material, desired electron conductivity can be obtained for the electrode even when the amount of conductive fibers added is small.

[0040] In a fourteenth aspect of this disclosure, for example, the manufacturing method according to the thirteenth aspect may further include mixing the slurry containing the conductive fibers and the binder with a slurry containing at least one selected from the group consisting of an active material and a solid electrolyte.

[0041] According to the 14th embodiment, the active material or solid electrolyte is dispersed in a slurry containing at least one selected from the group consisting of an active material and a solid electrolyte. In an electrode material obtained by mixing this slurry with a slurry containing conductive fibers and a binder, the dispersibility of the conductive fibers tends to be improved.

[0042] The battery relating to the 15th aspect of this disclosure is Positive electrode and, The negative electrode and, An electrolyte layer located between the positive electrode and the negative electrode, Equipped with, At least one selected from the group consisting of the positive electrode and the negative electrode comprises an active material, conductive fibers containing a carbon material, and a binder containing an elastomer. The elastomer is a hydrogenated material and contains repeating units having an aromatic ring. The content of the repeating units in the elastomer is 15% by mass or more.

[0043] According to the 15th embodiment, the electron conductivity is improved in either the positive or negative electrode. As a result, the battery tends to have not only a high energy density but also excellent cycle characteristics.

[0044] In a sixteenth aspect of this disclosure, for example, in the battery according to the fifteenth aspect, the electrolyte layer may include a solid electrolyte.

[0045] According to the 16th aspect, the battery tends to have not only a high energy density but also excellent cycle characteristics.

[0046] Embodiments of the present disclosure will be described below with reference to the drawings.

[0047] (Embodiment 1) Figure 1 shows a schematic diagram of the electrode material 100 according to Embodiment 1. The electrode material 100 in Embodiment 1 includes an active material 10, conductive fibers 11, and a binder 12. The conductive fibers 11 include a carbon material. The binder 12 includes an elastomer E. The elastomer E is a hydrogenated material and contains repeating units having aromatic rings. The content of repeating units having aromatic rings in the elastomer E is 15% by mass or more.

[0048] With the above configuration, in the electrode material 100 according to Embodiment 1, the binder 12 tends to adsorb onto the conductive fibers 11. By adsorbing the binder 12 onto the conductive fibers 11, the binder 12 can promote the dispersion of the conductive fibers 11 in the electrode material 100. As a result, the dispersibility of the conductive fibers 11 in the electrode material 100 is improved. Such an electrode material 100 is suitable for producing electrodes with improved electronic conductivity.

[0049] As described above, the electrode material 100 includes an active material 10, conductive fibers 11, and a binder 12. The electrode material 100 may further include a solid electrolyte 13, a solvent 14, and the like. These materials will be described in detail below.

[0050] [Active material] In Embodiment 1, the active material 10 is either a positive electrode active material or a negative electrode active material. The active material 10 may also be a negative electrode active material. If the active material 10 is a positive electrode active material, a positive electrode can be made from the electrode material 100. If the active material 10 is a negative electrode active material, a negative electrode can be made from the electrode material 100.

[0051] The positive electrode active material is, for example, a material that has the property of intercalating and releasing metal ions (e.g., lithium ions). Examples of positive electrode active materials include lithium-containing transition metal oxides, transition metal fluorides, polyanionic materials, fluorinated polyanionic materials, transition metal sulfides, transition metal oxysulfides, and transition metal oxynitrides. Examples of lithium-containing transition metal oxides include Li(Ni,Co,Al)O2, Li(Ni,Co,Mn)O2, and LiCoO2. When a lithium-containing transition metal oxide is used as the active material 10, the manufacturing cost of the positive electrode can be reduced, and the average discharge voltage of the battery can be improved.

[0052] The negative electrode active material is a material that has the property of intercalating and releasing metal ions (e.g., lithium ions). Examples of negative electrode active materials include metallic materials, carbon materials, oxides, nitrides, tin compounds, and silicon compounds. The metallic material may be a pure metal or an alloy. Examples of metallic materials include lithium metal and lithium alloys. Examples of carbon materials include natural graphite, coke, carbon in the process of graphitization, spheroidal carbon, artificial graphite, and amorphous carbon. By using silicon (Si), tin (Sn), silicon compounds, or tin compounds as the active material 10, the capacity density of the battery can be improved.

[0053] The median diameter of the active material 10 may be between 0.1 μm and 100 μm. When the median diameter of the active material is 0.1 μm or more, the active material 10 and the solid electrolyte 13 can be well dispersed in the electrode formed from the electrode material 100. Therefore, the charge and discharge characteristics of the battery using this electrode are improved. When the median diameter of the active material 10 is 100 μm or less, the lithium diffusion rate within the active material is improved. Therefore, the battery using the electrode formed from the electrode material 100 can operate at high power.

[0054] The median diameter refers to the particle size at which the cumulative volume in the volume-based particle size distribution equals 50%. The volume-based particle size distribution is determined by laser diffraction scattering. The same applies to the other materials listed below.

[0055] In the electrode material 100, the volume ratio "v1:100-v1" of the active material 10 to the solid electrolyte 13 may satisfy the condition 30 ≤ v1 ≤ 95. v1 represents the volume ratio of the active material 10 when the total volume of the active material 10 and solid electrolyte 13 contained in the electrode material 100 is set to 100. When 30 ≤ v1 is satisfied, it is easier to ensure a sufficient energy density for the battery. When v1 ≤ 95 is satisfied, it is easier to operate the battery at high power.

[0056] The active material 10 may be coated with a coating material to reduce interfacial resistance with the solid electrolyte 13. A material with low electronic conductivity may be used as the coating material. Examples of coating materials include oxide materials and oxide solid electrolytes.

[0057] Oxide materials that can be used as coating materials include SiO2, Al2O3, TiO2, B2O3, Nb2O5, WO3, and ZrO2.

[0058] Examples of oxide solid electrolytes used in coating materials include Li-Nb-O compounds such as LiNbO3, Li-BO compounds such as LiBO2 and Li3BO3, Li-Al-O compounds such as LiAlO2, Li-Si-O compounds such as Li4SiO4, Li-SO compounds such as Li2SO4, and Li4Ti5O 12 Possible examples of Li-Ti-O compounds, Li-Zr-O compounds such as Li2ZrO3, Li-Mo-O compounds such as Li2MoO3, Li-VO compounds such as LiV2O5, and Li-WO compounds such as Li2WO4 can be used. Oxide solid electrolytes have high ionic conductivity and high potential stability. Therefore, by using oxide solid electrolytes as coating materials, the charge and discharge efficiency of batteries can be further improved.

[0059] [Conductive Fibers] In Embodiment 1, the conductive fiber 11 containing carbon material can be carbon nanotubes (CNTs), carbon fibers, or vapor-processed carbon fibers. These conductive fibers 11 may be used individually or in combination of two or more types. The conductive fiber 11 may, for example, contain CNTs.

[0060] CNTs are cylindrical hollow fibers composed of graphene sheets. CNTs may be single-walled carbon nanotubes (SWCNTs) composed of one graphene sheet, or multi-walled carbon nanotubes (MWCNTs) composed of multiple graphene sheets. A specific example of an SWCNT is TUBALL®. In MWCNTs, the multiple graphene sheets are arranged, for example, in concentric circles. A specific example of an MWCNT is VGCF®-H.

[0061] The average fiber diameter of the conductive fiber 11 is, for example, 500 nm or less, but may also be 300 nm or less, 200 nm or less, 150 nm or less, 100 nm or less, 50 nm or less, 10 nm or less, or 5 nm or less. The smaller the average fiber diameter of the conductive fiber 11, the easier it is to increase the number of conductive fibers 11 while maintaining the amount of conductive fiber 11 added. Conductive fibers 11 with a small average fiber diameter can easily improve conductivity within the electrode. The lower limit of the average fiber diameter of the conductive fiber 11 is not particularly limited, and is, for example, 0.1 nm.

[0062] The average fiber diameter of the conductive fiber 11 can be determined by the following method. First, a conductive fiber 11 used as a raw material for producing the electrode material 100 is prepared as a measurement sample. The measurement sample may also be the electrode material 100. Next, the measurement sample is observed with a transmission electron microscope. In the obtained electron microscope image, the outer diameter of a specific conductive fiber 11 is measured at any multiple points (e.g., 10 points). The average of the obtained measurement values ​​is considered to be the fiber diameter of that conductive fiber 11. Alternatively, the fiber diameter of any number of conductive fibers 11 (e.g., 10 fibers) can be calculated, and the average of the calculated values ​​can be considered to be the average fiber diameter of the conductive fiber 11.

[0063] The average length of the conductive fibers 11 is not particularly limited and may be, for example, 1 μm or more, or 5 μm or more. The average length of the conductive fibers 11 may be 500 μm or less, 250 μm or less, 100 μm or less, 50 μm or less, or 10 μm or less.

[0064] The average length of the conductive fibers 11 can be determined by the following method. First, prepare the measurement sample described above for the average fiber diameter. Next, observe the measurement sample with a transmission electron microscope. Measure the length of specific conductive fibers 11 in the obtained electron microscope image. Calculate the length of any number of conductive fibers 11 (for example, 10), and the average of the calculated values ​​can be considered as the average length of the conductive fibers 11.

[0065] The aspect ratio of the conductive fiber 11, calculated as the ratio of the average length to the average fiber diameter, is not particularly limited and may be, for example, 2 to 50000, 5 to 20000, or 10 to 10000. The aspect ratio of the conductive fiber 11 may, in some cases, be greater than 1000, or 3000 or more.

[0066] The conductive fiber 11 contains, for example, a carbon material as its main component. "Main component" means the component that is present in the largest mass ratio in the conductive fiber 11. The conductive fiber 11 consists, for example, substantially of a carbon material. "Substantially of..." means excluding other components that alter the essential properties of the material mentioned.

[0067] [binder] As described above, binder 12 contains elastomer E. In this disclosure, elastomer means an elastic polymer. Elastomer E is a hydrogenated material. For example, in elastomer E, carbon-carbon double bonds are hydrogenated and changed to single bonds. Furthermore, elastomer E contains repeating units having aromatic rings. Repeating units refer to molecular structures derived from monomers and are sometimes called constituent units. The content of repeating units having aromatic rings in elastomer E is 15% by mass or more.

[0068] In this disclosure, an aromatic ring means a cyclic structure having aromatic properties. Examples of aromatic rings contained in elastomer E include benzene rings, naphthalene rings, and other benzene-based aromatic rings; non-benzene-based aromatic rings, such as tropylium rings; and heteroaromatic rings, such as pyridine rings and pyrrole rings. The aromatic ring may also contain a benzene ring.

[0069] Monomers that form repeating units having an aromatic ring include styrene, phenyl methacrylate, and benzyl methacrylate. Repeating units having an aromatic ring include, for example, repeating units derived from styrene.

[0070] Elastomer E may further contain repeating units derived from a conjugated diene, along with repeating units having an aromatic ring. Examples of conjugated dienes include butadiene and isoprene. In elastomer E, for example, the repeating units derived from the conjugated diene are hydrogenated. That is, in elastomer E, the repeating units derived from the conjugated diene do not have unsaturated bonds such as carbon-carbon double bonds. However, not all repeating units derived from the conjugated diene in elastomer E are hydrogenated. Elastomer E may contain repeating units having unsaturated bonds.

[0071] Elastomer E may further contain modifying groups. A modifying group refers to a functional group that chemically modifies all repeating units in the polymer chain, some repeating units in the polymer chain, or the terminal portion of the polymer chain. Modifying groups can be introduced into the polymer chain by substitution reactions, addition reactions, etc. Modifying groups include, for example, elements such as O and N, which have relatively high electronegativity. By using modifying groups containing such elements, polarity can be imparted to elastomer E. Examples of modifying groups include carboxylic acid groups, acid anhydride groups, acyl groups, hydroxyl groups, sulfo groups, sulfanyl groups, phosphoric acid groups, phosphonic acid groups, isocyanate groups, epoxy groups, silyl groups, amino groups, nitrile groups, and nitro groups. A specific example of an acid anhydride group is the maleic anhydride group.

[0072] Elastomer E is a copolymer containing, for example, repeating units having aromatic rings and repeating units derived from a conjugated diene. This copolymer may be a random copolymer or a block copolymer. An example of a random copolymer elastomer E is a hydrogenated styrene-butadiene random copolymer (hydrogenated SBR).

[0073] The block copolymer elastomer E may have a first block that functions as a hard segment and a second block that functions as a soft segment. In this case, elastomer E functions as a thermoplastic elastomer. In this disclosure, elastomer E that functions as a thermoplastic elastomer may be referred to as thermoplastic elastomer T. The number of first blocks in thermoplastic elastomer T may be one or more, or two or more. For example, in thermoplastic elastomer T, a second block may be located between two first blocks. Thermoplastic elastomer T may be an ABA-type triblock copolymer. In this case, the compositions of the two first blocks contained in thermoplastic elastomer T may be the same or different. Furthermore, the degrees of polymerization of the two first blocks may be the same or different.

[0074] In a thermoplastic elastomer T, for example, the first block contains repeating units having aromatic rings. The first block may be composed of repeating units having aromatic rings. Examples of polymers constituting the first block include polystyrene, polyphenyl methacrylate, polybenzyl methacrylate, polyphenylene, polyaryl ether ketone, polyaryl ether sulfone, and polyphenylene oxide. In the first block, the repeating units having aromatic rings include, for example, repeating units derived from styrene. In this disclosure, a thermoplastic elastomer containing repeating units derived from styrene may be referred to as a styrene-based thermoplastic elastomer (TPS).

[0075] In thermoplastic elastomer T, for example, the second block contains repeating units derived from a conjugated diene. The second block may be composed of repeating units derived from a conjugated diene. In thermoplastic elastomer T, for example, the repeating units derived from the conjugated diene in the second block are hydrogenated. That is, in the second block, the repeating units derived from the conjugated diene do not have unsaturated bonds such as carbon-carbon double bonds. However, not all repeating units derived from the conjugated diene in the second block are hydrogenated. The second block may contain repeating units having unsaturated bonds. In this disclosure, hydrogenated styrene-based thermoplastic elastomers having unsaturated bonds such as carbon-carbon double bonds are sometimes referred to as hydrogenated styrene-based thermoplastic elastomers.

[0076] Examples of thermoplastic elastomers T include styrene-butadiene / butylene-styrene block copolymer (SBBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene / ethylene / propylene-styrene block copolymer (SEEPS), and copolymers of these in which modified groups have been introduced. Elastomer E may contain at least one selected from the group consisting of SEBS and SEEPS as the thermoplastic elastomer T. Note that SBBS is a polymer in which the 1,2-vinyl bond (-CH2CH(CH=CH2)-) contained in styrene-butadiene-styrene block copolymer (SBS) is hydrogenated.

[0077] Figure 2 shows an example of an elastomer. Figure 2 shows specific examples of elastomers before hydrogenation (unsaturated) and after hydrogenation (hydrogenated). The hydrogenated product in Figure 2 is a specific example of elastomer E contained in binder 12. As shown in Figure 2, specific examples of unsaturated products include styrene-butadiene random copolymer (SBR) represented by formula (i), styrene-isoprene-styrene block copolymer (SIS) represented by formula (ii), and styrene-butadiene-styrene block copolymer (SBS) represented by formula (iii). As can be seen from Figure 2, hydrogenated SBR represented by formula (iv) is a hydrogenated product of SBR. SEPS represented by formula (v) is a hydrogenated product of SIS. SEBS represented by formula (vi) is a hydrogenated product of SBS. SEEPS represented by formula (vii) is a hydrogenated product of styrene-isoprene / butadiene-styrene block copolymer.

[0078] In the binder 12, the hydrogenation rate of the elastomer E is, for example, 30% or more, may be 50% or more, 70% or more, 90% or more, 95% or more, or 99% or more. The higher the hydrogenation rate of the elastomer E, the more the binder 12 tends to improve the dispersibility of the conductive fibers 11. The hydrogenation rate of the elastomer E refers to the ratio of the number of carbon-carbon double bonds that have been changed from carbon-carbon double bonds to single bonds by hydrogenation to the number of carbon-carbon double bonds contained in the elastomer before hydrogenation.

[0079] As described above, the content of repeating units having aromatic rings in elastomer E is 15% by mass or more. This content may be 16% by mass or more, 20% by mass or more, 30% by mass or more, or 40% by mass or more. The higher the content of repeating units having aromatic rings, the more the binder 12 tends to improve the dispersibility of the conductive fibers 11. The upper limit of the content of repeating units having aromatic rings is not particularly limited, and may be, for example, 70% by mass, 67% by mass or 60% by mass. In this disclosure, when the repeating units having aromatic rings are repeating units derived from styrene, the content of repeating units derived from styrene in elastomer E may be called the styrene ratio. The content of repeating units having aromatic rings in elastomer E is related to proton nuclear magnetic resonance ( 1 This can be determined by 1H NMR measurement.

[0080] Weight-average molecular weight (M) of elastomer E w The weight-average molecular weight of elastomer E is not particularly limited and may be, for example, 1,000,000 or less, 500,000 or less, 400,000 or less, 300,000 or less, 200,000 or less, or 100,000 or less. The lower limit of the weight-average molecular weight of elastomer E is not particularly limited and may be, for example, 1,000. The weight-average molecular weight of elastomer E can be determined by gel permeation chromatography (GPC) measurement using polystyrene as a standard sample. In other words, the weight-average molecular weight is the value converted using polystyrene. In GPC measurement, chloroform may be used as the eluent. If two or more peak tops are observed in the GPC chart, the weight-average molecular weight calculated from the overall peak range including each peak top can be considered as the weight-average molecular weight of elastomer E.

[0081] The binder 12 may contain elastomer E as its main component. For example, the binder 12 may consist substantially of elastomer E.

[0082] Furthermore, the electrode material 100 may contain a nonpolar solvent as the solvent 14 in order to suppress the reaction with the solid electrolyte 13. Since elastomer E tends to have high solubility in nonpolar solvents, it dissolves easily in the electrode material 100 containing a nonpolar solvent. As elastomer E dissolves in the electrode material 100, the binder 12 tends to be easily adsorbed onto the conductive fibers 11.

[0083] Binder 12 may further contain other polymers besides elastomer E. Other polymers that can function as a binder include, for example, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamide-imide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polycarbonate, polyethersulfone, polyether ketone, polyetherether ketone, polyphenylene sulfide, hexafluoropolypropylene, styrene-butadiene rubber, carboxymethylcellulose, and ethylcellulose. Other polymers that can be used include copolymers synthesized using two or more monomers selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, butadiene, styrene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid esters, acrylic acid, and hexadiene. These binders may be used individually or in combination of two or more.

[0084] Binder 12 may further contain other elastomers besides elastomer E as other polymers. Other elastomers that may be included in binder 12 include butylene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), styrene-butylene rubber (SBR), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), hydrogenated isoprene rubber (HIR), hydrogenated butyl rubber (HIIR), and hydrogenated nitrile rubber (HNBR). Two or more of these may be mixed and used as the elastomer.

[0085] [Solid electrolyte] In Embodiment 1, the solid electrolyte 13 has, for example, lithium ion conductivity. As the solid electrolyte 13, sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, polymer solid electrolytes, complex hydride solid electrolytes, and the like can be used. The solid electrolyte 13 may also contain a halide solid electrolyte.

[0086] In this disclosure, “oxide solid electrolyte” means a solid electrolyte containing oxygen. The oxide solid electrolyte may further contain anions other than oxygen, such as sulfur and halogen elements.

[0087] In this disclosure, "halide solid electrolyte" means a solid electrolyte that contains a halogen element but does not contain sulfur. In this disclosure, a sulfur-free solid electrolyte means a solid electrolyte represented by a composition formula that does not contain a sulfur element. Therefore, a solid electrolyte containing a very small amount of sulfur, for example, a sulfur component of 0.1% by mass or less, is included in the category of sulfur-free solid electrolytes. A halide solid electrolyte may also contain oxygen as an anion other than a halogen element.

[0088] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, Li 3.25 Ge0.25 P 0.75 S4, Li 10 GeP2S 12 and the like can be used. To these, LiX, Li2O, MO q , Li p MO q and the like may be added. The element X in "LiX" is at least one selected from the group consisting of F, Cl, Br and I. In "MO q " and "Li p MO q ", the element M is at least one selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn. In "MO q " and "Li p MO q ", p and q are each independently natural numbers.

[0089] Examples of oxide solid electrolytes include NASICON-type solid electrolytes represented by LiTi2(PO4)3 and elemental substitution products thereof, (LaLi)TiO3-based perovskite-type solid electrolytes, Li 14 ZnGe4O 16 , LISICON-type solid electrolytes represented by Li4SiO4, LiGeO4 and elemental substitution products thereof, Li7La3Zr2O 12 garnet-type solid electrolytes represented by the compound and elemental substitution products thereof, Li3PO4 and N-substitution products thereof, glasses obtained by adding Li2SO4, Li2CO3 and the like based on Li-B-O compounds such as LiBO2 and Li3BO3, and glass-ceramics and the like can be used.

[0090] A halide solid electrolyte contains, for example, Li, M, and X. M is at least one selected from the group consisting of metal elements other than Li and metalloid elements. X is at least one selected from the group consisting of F, Cl, Br, and I. Since the halide solid electrolyte has high thermal stability, it can improve the safety of the battery. Furthermore, since the halide solid electrolyte does not contain sulfur, generation of hydrogen sulfide gas can be suppressed.

[0091] In this disclosure, “metallic elements” are B, Si, Ge, As, Sb, and Te.

[0092] In this disclosure, “metallic elements” refers to all elements in groups 1 through 12 of the periodic table, excluding hydrogen, and all elements in groups 13 through 16 of the periodic table, excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se.

[0093] In other words, in this disclosure, "metalloid elements" and "metal elements" are a group of elements that can become cations when they form inorganic compounds with halogen elements.

[0094] For example, the halide solid electrolyte may be a material represented by the following compositional formula (1). Li α M β X γ ...Equation (1)

[0095] In the above empirical formula (1), α, β, and γ are each independently greater than 0. γ can be 4, 6, etc.

[0096] With the above configuration, the ionic conductivity of the halide solid electrolyte is improved, and therefore the ionic conductivity of the electrode formed from the electrode material 100 in Embodiment 1 can be improved. When this electrode is used in a battery, the cycle characteristics of the battery can be further improved.

[0097] In the above compositional formula (1), element M may also include Y (=yttrium). That is, the halide solid electrolyte may contain Y as a metallic element.

[0098] A halide solid electrolyte containing Y may be represented, for example, by the following compositional formula (2). Li a Me b Y c X6...Formula (2)

[0099] In formula (2), a, b, and c may satisfy a+mb+3c=6 and c>0. The element Me is at least one selected from the group consisting of metal elements and metalloid elements other than Li and Y. m represents the valence of the element Me. When the element Me includes a plurality of types of elements, mb is the total sum of products of the composition ratio of each element and the valence of that element. For example, when Me includes element Me1 and element Me2, the composition ratio of element Me1 is b1, the valence of element Me1 is m1, the composition ratio of element Me2 is b2, and the valence of element Me2 is m2, mb is represented by m1b1+m2b2. In the above composition formula (2), the element X is at least one selected from the group consisting of F, Cl, Br, and I.

[0100] The element Me may be, for example, at least one selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, Gd and Nb.

[0101] As the halide solid electrolyte, for example, the following materials may be used. According to the following materials, the ionic conductivity of the solid electrolyte 13 is further improved, so the ionic conductivity of the electrode formed from the electrode material 100 in Embodiment 1 can be further improved. According to this electrode, the cycle characteristics of the battery can be further improved.

[0102] The halide solid electrolyte may be a material represented by the following composition formula (A1). Li 6-3d Y d X6···Formula (A1)

[0103] In composition formula (A1), the element X is at least one selected from the group consisting of Cl, Br, and I. In composition formula (A1), d satisfies 0<d<2.

[0104] The halide solid electrolyte may be a material represented by the following composition formula (A2). Li3YX6···Formula (A2)

[0105] In the composition formula (A2), element X is at least one selected from the group consisting of Cl, Br, and I.

[0106] The halide solid electrolyte may be a material represented by the following compositional formula (A3). Li 3-3δ Y 1+δ Cl6...Formula (A3)

[0107] In empirical formula (A3), δ satisfies 0 < δ ≤ 0.15.

[0108] The halide solid electrolyte may be a material represented by the following compositional formula (A4). Li 3-3δ Y 1+δ Br6...Formula (A4)

[0109] In empirical formula (A4), δ satisfies 0 < δ ≤ 0.25.

[0110] The halide solid electrolyte may be a material represented by the following compositional formula (A5). Li 3-3δ+a Y 1+δ-a Me a Cl 6-x-y Br x I y ...Formula (A5)

[0111] In compositional formula (A5), the element Me is at least one selected from the group consisting of Mg, Ca, Sr, Ba, and Zn.

[0112] Furthermore, in the above composition formula (A5), -1 < δ < 2, 0 <a<3、 0 < (3 - 3δ + a), 0 < (1 + δ - a), 0 ≤ x ≤ 6, 0≦y≦6, and (x+y)≦6, The conditions are met.

[0113] The halide solid electrolyte may be a material represented by the following compositional formula (A6). Li 3-3δ Y 1+δ-a Me a Cl 6-x-y Br x I y ...Formula (A6)

[0114] In the composition formula (A6), the element Me is at least one selected from the group consisting of Al, Sc, Ga, and Bi.

[0115] Furthermore, in the above composition formula (A6), -1 < δ < 1, 0 <a<2、 0 < (1 + δ - a), 0 ≤ x ≤ 6, 0≦y≦6, and (x+y)≦6, The conditions are met.

[0116] The halide solid electrolyte may be a material represented by the following compositional formula (A7). Li 3-3δ-a Y 1+δ-a Me a Cl 6-x-y Br x I y ...Formula (A7)

[0117] In the composition formula (A7), the element Me is at least one selected from the group consisting of Zr, Hf, and Ti.

[0118] Furthermore, in the above composition formula (A7), -1 < δ < 1, 0 <a<1.5、 0 < (3 - 3δ - a), 0 < (1 + δ - a), 0 ≤ x ≤ 6, 0≦y≦6, and (x+y)≦6, The conditions are met.

[0119] The halide solid electrolyte may be a material represented by the following compositional formula (A8). Li 3-3δ-2a Y 1+δ-a Me a Cl 6-x-y Br x I y ...Formula (A8)

[0120] In the composition formula (A8), the element Me is at least one selected from the group consisting of Ta and Nb.

[0121] Furthermore, in the above composition formula (A8), -1 < δ < 1, 0 <a<1.2、 0<(3-3δ-2a), 0 < (1 + δ - a), 0 ≤ x ≤ 6, 0≦y≦6, and (x+y)≦6, The conditions are met.

[0122] More specifically, as a solid halide electrolyte, for example, Li3YX6, Li 2.7 YX6, Li2MgX4, Li2FeX4, Li(Al,Ga,In)X4, Li3(Al,Ga,In)X 6、 Li3(Ti,Al)X6, Li 2.7 (Ti,Al)X6 and similar materials may be used. In these materials, element X is at least one selected from the group consisting of F, Cl, Br, and I. In this disclosure, when an element in a formula is represented as "(Al,Ga,In)", this notation indicates at least one element selected from the group of elements in parentheses. That is, "(Al,Ga,In)" is synonymous with "at least one selected from the group consisting of Al, Ga, and In". The same applies to other elements.

[0123] As a polymer solid electrolyte, for example, a compound of a polymer compound and a lithium salt can be used. The polymer compound may have an ethylene oxide structure. Polymer compounds having an ethylene oxide structure can contain a large amount of lithium salt. Therefore, the ionic conductivity can be further improved. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), and LiC(SO2CF3)3. A single lithium salt may be used, or two or more may be used in combination.

[0124] Examples of complex hydride solid electrolytes that can be used include LiBH4-LiI and LiBH4-P2S5.

[0125] If the solid electrolyte 13 is particulate (for example, spherical), the median diameter of the solid electrolyte 13 may be 1 μm or more and 100 μm or less, or 1 μm or more and 10 μm or less. When the median diameter of the solid electrolyte 13 is 1 μm or more and 100 μm or less, the solid electrolyte 13 can be easily dispersed in the solvent 14.

[0126] If the solid electrolyte 13 is particulate (for example, spherical), the median diameter of the solid electrolyte 13 may be 0.1 μm or more and 1 μm or less. When the median diameter of the solid electrolyte 13 is 0.1 μm or more and 1 μm or less, the electrode made from the electrode material 100 may have higher surface smoothness and a denser structure.

[0127] In the electrode material 100, the median diameter of the solid electrolyte 13 may be smaller than the median diameter of the active material 10. This allows the solid electrolyte 13 and the active material 10 to be well dispersed.

[0128] [solvent] The solvent 14 may be an organic solvent. An organic solvent is a compound containing carbon, such as a compound containing elements such as carbon, hydrogen, nitrogen, oxygen, sulfur, or halogen. The solvent 14 is, for example, a nonpolar solvent. The solvent 14 can dissolve, for example, the binder 12. When the binder 12 is dissolved in the solvent 14, the conductive fibers 11 tend to disperse easily by the binder 12. However, the binder 12 does not have to be dissolved in the solvent 14.

[0129] The solvent 14 may include at least one selected from the group consisting of hydrocarbons, compounds having halogen groups, and compounds having ether bonds.

[0130] Hydrocarbons are compounds consisting only of carbon and hydrogen. Hydrocarbons may be aliphatic hydrocarbons. Hydrocarbons may be saturated hydrocarbons or unsaturated hydrocarbons. Hydrocarbons may be linear or branched. The number of carbon atoms in a hydrocarbon is not particularly limited and may be seven or more. By using hydrocarbons, an electrode material 100 with excellent dispersibility of the solid electrolyte 13 can be obtained. Furthermore, the decrease in the ionic conductivity of the solid electrolyte 13 due to mixing with the solvent 14 can be suppressed.

[0131] The hydrocarbon may have a ring structure. The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. The ring structure may be monocyclic or polycyclic. The presence of a ring structure in the hydrocarbon allows the solid electrolyte 13 to disperse easily in the solvent 14. From the viewpoint of improving the dispersibility of the solid electrolyte 13 in the electrode material 100, the hydrocarbon may contain aromatic hydrocarbons. That is, the solvent 14 may contain aromatic hydrocarbons. The hydrocarbon may also be an aromatic hydrocarbon.

[0132] A compound having a halogen group may consist only of carbon and hydrogen in the parts other than the halogen group. That is, a compound having a halogen group means a compound in which at least one hydrogen atom contained in a hydrocarbon is replaced with a halogen group. Examples of halogen groups include F, Cl, Br, and I. At least one selected from the group consisting of F, Cl, Br, and I may be used as the halogen group. A compound having a halogen group may have high polarity. By using a compound having a halogen group in the solvent 14, the solid electrolyte 13 can be easily dispersed in the solvent 14, so an electrode material 100 with excellent dispersibility can be obtained. As a result, the electrode produced from the electrode material 100 may have excellent ionic conductivity and a denser structure.

[0133] The number of carbon atoms in the halogen-containing compound is not particularly limited and may be seven or more. This allows for the stable production of electrode material 100 because the halogen-containing compound is less volatile. The halogen-containing compound may have a large molecular weight; that is, it may have a high boiling point.

[0134] The compound having a halogen group may have a ring structure. The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. The ring structure may be monocyclic or polycyclic. The presence of a ring structure in the compound having a halogen group allows the solid electrolyte 13 to disperse easily in the solvent 14. From the viewpoint of improving the dispersibility of the solid electrolyte 13 in the electrode material 100, the compound having a halogen group may contain an aromatic hydrocarbon. The compound having a halogen group may also contain an aromatic hydrocarbon.

[0135] A compound having a halogen group may have only a halogen group as a functional group. In this case, the number of halogens contained in the compound having a halogen group is not particularly limited. At least one selected from the group consisting of F, Cl, Br, and I may be used as the halogen group. By using such a compound in the solvent 14, the solid electrolyte 13 can be easily dispersed in the solvent 14, so that an electrode material 100 with excellent dispersibility can be obtained. As a result, the electrode produced from the electrode material 100 may have excellent ionic conductivity and a denser structure. By using such a compound in the solvent 14, the electrode produced from the electrode material 100 may easily have a dense structure with fewer pinholes, unevenness, etc.

[0136] The compound having a halogen group may be a halogenated hydrocarbon. A halogenated hydrocarbon means a compound in which all the hydrogen atoms in the hydrocarbon are replaced by halogen groups. By using a halogenated hydrocarbon as the solvent 14, the solid electrolyte 13 can be easily dispersed in the solvent 14, so that an electrode material 100 with excellent dispersibility can be obtained. As a result, the electrode produced from the electrode material 100 may have excellent ionic conductivity and a denser structure. By using such a compound as the solvent 14, the electrode produced from the electrode material 100 may easily have a dense structure with fewer pinholes, unevenness, etc.

[0137] Compounds having ether bonds may consist only of carbon and hydrogen in the parts other than the ether bond. That is, a compound having an ether bond means a compound in which at least one of the CC bonds contained in a hydrocarbon is replaced with a COC bond. Compounds having ether bonds may have high polarity. By using a compound having an ether bond in solvent 14, the solid electrolyte 13 can be easily dispersed in solvent 14. Therefore, an electrode material 100 with excellent dispersibility can be obtained. As a result, electrodes manufactured from electrode material 100 may have excellent ionic conductivity and a denser structure.

[0138] The compound having an ether bond may have a ring structure. The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. The ring structure may be monocyclic or polycyclic. The presence of a ring structure in the compound having an ether bond allows the solid electrolyte 13 to disperse easily in the solvent 14. From the viewpoint of improving the dispersibility of the solid electrolyte 13 in the electrode material 100, the compound having an ether bond may contain an aromatic hydrocarbon. The compound having an ether bond may be an aromatic hydrocarbon.

[0139] Examples of solvent 14 include toluene, ethylbenzene, mesitylene, pseudocumene, p-xylene, cumene, tetralin, m-xylene, dibutyl ether, 1,2,4-trichlorobenzene, chlorobenzene, 2,4-dichlorotoluene, anisole, o-chlorotoluene, m-dichlorobenzene, p-chlorotoluene, o-dichlorobenzene, 1,4-dichlorobutane, and 3,4-dichlorotoluene. These may be used individually or in combination of two or more.

[0140] The boiling point of solvent 14 may be between 100°C and 250°C. Solvent 14 may also be a liquid at room temperature (25°C). Since such a solvent does not easily volatilize at room temperature, the electrode material 100 can be manufactured stably. Therefore, an electrode material 100 that can be easily applied to the surface of a current collector or substrate can be obtained. The solvent 14 contained in the electrode material 100 can be easily removed when the electrode is manufactured.

[0141] The water content of solvent 14 may be 10 ppm by mass or less. Reducing the water content can suppress the decrease in ionic conductivity due to the reaction of solid electrolyte 13. Methods for reducing the water content include dehydration using molecular sieves and dehydration by bubbling with an inert gas such as nitrogen or argon. Dehydration by bubbling with an inert gas is recommended from the viewpoint of removing oxygen at the same time as water. The water content can be measured with a Karl Fischer moisture analyzer.

[0142] The solvent 14 may be a liquid capable of dispersing the solid electrolyte 13. The solid electrolyte 13 does not necessarily have to be dissolved in the solvent 14. By preventing the solid electrolyte 13 from dissolving in the solvent 14, an electrode material 100 can be produced in which the ion-conducting phase formed during the production of the solid electrolyte 13 is preserved. Therefore, in electrodes produced using this electrode material 100, a decrease in ion conductivity can be suppressed.

[0143] The solvent 14 may partially or completely dissolve the solid electrolyte 13. Dissolving the solid electrolyte 13 can improve the density of the electrode manufactured using this electrode material 100.

[0144] [Other ingredients] The electrode material 100 may further contain other materials besides those described above. Other materials include conductive additives other than the conductive fibers 11. Examples of other conductive additives include graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black and Ketjen black, metal fibers, conductive powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymers such as polyaniline, polypyrrole and polythiophene.

[0145] [Electrode material] The electrode material 100 may be in paste form or in dispersion form. The materials described above are mixed together in the electrode material 100. The solid content concentration of the electrode material 100 is not particularly limited and may be 20% by mass or more and 70% by mass or less, or 30% by mass or more and 60% by mass or less.

[0146] [Method for manufacturing electrode materials] The method for manufacturing the electrode material 100 is described below. The method for manufacturing the electrode material 100 in this embodiment includes preparing a slurry containing conductive fibers 11 and a binder 12. The method for manufacturing the electrode material 100 may further include mixing the slurry containing conductive fibers 11 and a binder 12 with a slurry containing at least one selected from the group consisting of active material 10 and solid electrolyte 13. In this disclosure, the slurry containing conductive fibers 11 and a binder 12 may be referred to as the first slurry. The slurry containing at least one selected from the group consisting of active material 10 and solid electrolyte 13 may be referred to as the second slurry.

[0147] Figure 3 is a flowchart of an example of a method for manufacturing electrode material 100. As shown in Figure 3, in the method for manufacturing electrode material 100, first, in step S01, conductive fibers 11, binder 12, and solvent 14 are mixed. For example, these materials may be mixed by adding conductive fibers 11 to a solution obtained by dissolving binder 12 in solvent 14. In step S01, in addition to these materials, other dispersants may or may not be mixed. Depending on the combination of binder 12 and dispersant, the amount of dispersant used may be reduced compared to conventional methods. The dispersant may also improve the dispersion stability of the conductive fibers 11. The dispersant may have the function of dispersing the active material 10 or solid electrolyte 13 that will be mixed in a later step. Next, in step S02, the obtained mixture is subjected to a dispersion treatment. The method of the dispersion treatment is not particularly limited. In the dispersion process, for example, dispersion devices such as stirring type, shaking type, ultrasonic type, and rotary type may be used, and dispersion and kneading devices such as high-speed homogenizers, ultrasonic homogenizers, ball mills, bead mills, planetary mixers, sand mills, roll mills, and kneaders may be used. In the dispersion process, one type of these devices may be used alone, or two or more types may be used in combination. The first slurry can be prepared by the dispersion process in step S02 (step S03).

[0148] Next, in step S04, the active material 10 and solvent 14 are mixed. In step S04, in addition to these materials, a binder 12, other dispersants, etc., may be further mixed. Next, in step S05, the resulting mixture is subjected to a dispersion treatment. The apparatus described above for step S02 can be used for the dispersion treatment. The dispersion treatment in step S05 yields a second slurry (step S06).

[0149] Next, in step S07, the first slurry, the second slurry, and the solid electrolyte 13 are mixed. Then, in step S08, the mixture obtained in step S07 is subjected to a dispersion treatment. The apparatus described above for step S02 can be used for the dispersion treatment. The electrode material 100 can be obtained by the dispersion treatment in step S08 (step S09).

[0150] In the flowchart of Figure 3, in step S04, the solid electrolyte 13 may be used instead of the active material 10. In this case, in step S07, the active material 10 is mixed with the first slurry and the second slurry instead of the solid electrolyte 13.

[0151] Figure 4 is a flowchart showing another example of a method for manufacturing the electrode material 100. In the manufacturing method shown in Figure 4, in step S07, the first slurry and the second slurry are mixed. The resulting mixture is subjected to a dispersion treatment (step S10). Next, in step S11, the dispersed mixture is mixed with the solid electrolyte 13. In step S12, the resulting mixture is subjected to a dispersion treatment. The electrode material 100 can be obtained by the dispersion treatment in step S12 (step S09). Except for the above, the manufacturing method shown in Figure 4 is the same as the manufacturing method shown in Figure 3. Therefore, steps common to the manufacturing method shown in Figure 4 and the manufacturing method shown in Figure 3 are given the same reference numerals, and their descriptions may be omitted. That is, the following descriptions of each manufacturing method can be applied to each other as long as they do not contradict each other in technical terms. Furthermore, each manufacturing method can be combined with each other as long as they do not contradict each other in technical terms.

[0152] In steps S10 and S12, the apparatus described above for step S02 can be used in the distributed processing. In the flowchart of Figure 4, in step S04, the solid electrolyte 13 may be used instead of the active material 10. In this case, in step S11, the active material 10 is used instead of the solid electrolyte 13.

[0153] Figure 5 is a flowchart showing another example of a method for manufacturing the electrode material 100. In the manufacturing method shown in Figure 5, after step S03, the first slurry and the solid electrolyte 13 are mixed (step S21). In step S22, the resulting mixture is subjected to a dispersion treatment. Next, in step S23, the dispersed mixture is mixed with the second slurry. In step S24, the resulting mixture is subjected to a dispersion treatment. The electrode material 100 can be obtained by the dispersion treatment in step S24 (step S09). Except for the above, the manufacturing method shown in Figure 5 is the same as the manufacturing method shown in Figure 3. In steps S22 and S24, the apparatus described above for step S02 can be used for the dispersion treatment. In the manufacturing method shown in Figure 5, the mixture subjected to the dispersion treatment in step S22 can also be considered as the first slurry containing the conductive fibers 11 and the binder 12. Note that in the flowchart of Figure 5, the solid electrolyte 13 may be used instead of the active material 10 in step S04. In this case, in step S21, the active material 10 is mixed with the first slurry instead of the solid electrolyte 13.

[0154] Figure 6 is a flowchart of another example of a method for manufacturing the electrode material 100. In the manufacturing method shown in Figure 6, after step S06, the second slurry and the solid electrolyte 13 are mixed (step S31). In step S32, the resulting mixture is subjected to a dispersion treatment. Next, in step S33, the dispersed mixture is mixed with the first slurry. In step S34, the resulting mixture is subjected to a dispersion treatment. The electrode material 100 can be obtained by the dispersion treatment in step S34 (step S09). Except for the above, the manufacturing method shown in Figure 6 is the same as the manufacturing method shown in Figure 3. In steps S32 and S34, the apparatus described above for step S02 can be used for the dispersion treatment. In the manufacturing method shown in Figure 6, the mixture subjected to the dispersion treatment in step S32 can also be considered as the second slurry. Note that in the flowchart of Figure 6, in step S04, the solid electrolyte 13 may be used instead of the active material 10. In this case, in step S31, the active material 10 is mixed with the second slurry instead of the solid electrolyte 13.

[0155] Figure 7 is a flowchart showing another example of a method for manufacturing the electrode material 100. In the manufacturing method shown in Figure 7, in step S41, the solid electrolyte 13 and solvent 14 are mixed. In step S41, in addition to these materials, a binder 12, a dispersant, etc., may be further mixed. Next, in step S42, the obtained mixture is subjected to a dispersion treatment. The dispersion treatment in step S42 yields a third slurry (step S43). Next, in step S44, the first slurry, the second slurry, and the third slurry are mixed. In step S45, the obtained mixture is subjected to a dispersion treatment. The dispersion treatment in step S45 yields the electrode material 100 (step S09). Except for the above, the manufacturing method shown in Figure 7 is the same as the manufacturing method shown in Figure 3. In steps S42 and S45, the apparatus described above for step S02 can be used for the dispersion treatment.

[0156] In the manufacturing methods shown in Figures 3 to 7, a first slurry containing conductive fibers 11 and a binder 12 is mixed with a second slurry containing at least one selected from the group consisting of an active material 10 and a solid electrolyte 13. Electrode materials 100 produced by such manufacturing methods tend to exhibit improved dispersibility of the conductive fibers 11.

[0157] (Embodiment 2) Embodiment 2 will be described below. Descriptions that overlap with Embodiment 1 described above will be omitted as appropriate.

[0158] Figure 8 shows a cross-sectional view of the battery 200 according to Embodiment 2.

[0159] The battery 200 in Embodiment 2 comprises a positive electrode 20, a negative electrode 40, and an electrolyte layer 30.

[0160] At least one selected from the group consisting of the positive electrode 20 and the negative electrode 40 is formed from the electrode material 100 in Embodiment 1 described above. That is, at least one selected from the group consisting of the positive electrode 20 and the negative electrode 40 includes the active material 10, conductive fibers 11 and binder 12 described in Embodiment 1. At least one selected from the group consisting of the positive electrode 20 and the negative electrode 40 may further include the solid electrolyte 13 described in Embodiment 1.

[0161] The electrolyte layer 30 is located between the positive electrode 20 and the negative electrode 40.

[0162] With the above configuration, the battery 200 of Embodiment 2 not only has a high energy density but also tends to have excellent cycle characteristics.

[0163] As shown in Figure 8, in the battery 200 of Embodiment 2, the negative electrode 40 may be formed from the electrode material 100 of Embodiment 1 described above. That is, the negative electrode 40 may include the active material 10, conductive fiber 11, and binder 12 described in Embodiment 1. Below, a battery 200 equipped with a negative electrode 40 formed from the electrode material 100 will be described.

[0164] The electrolyte layer 30 is a layer containing an electrolyte material. Examples of the electrolyte material include solid electrolytes. That is, the electrolyte layer 30 may be a solid electrolyte layer containing a solid electrolyte. As the solid electrolyte contained in the electrolyte layer 30, the solid electrolytes exemplified as the solid electrolyte 13 of Embodiment 1 may be used, for example, sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, polymer solid electrolytes, complex hydride solid electrolytes, etc. may be used. The solid electrolyte may also be a halide solid electrolyte. Since halide solid electrolytes have high thermal stability, the safety of the battery 200 can be improved.

[0165] The electrolyte layer 30 may contain a solid electrolyte as its main component. The electrolyte layer 30 may contain a solid electrolyte in an amount of 70% or more (70% by mass or more) by mass relative to the total weight of the electrolyte layer 30.

[0166] With the above configuration, the charge and discharge characteristics of battery 200 can be improved.

[0167] The electrolyte layer 30 mainly contains a solid electrolyte, and may also contain unavoidable impurities, or starting materials, by-products, and decomposition products used when synthesizing the solid electrolyte.

[0168] The electrolyte layer 30 may contain 100% (100% by mass) of solid electrolyte relative to the total mass of the electrolyte layer 30, excluding impurities that are unavoidable to be present.

[0169] With the above configuration, the charge and discharge characteristics of battery 200 can be further improved.

[0170] The electrolyte layer 30 may contain two or more of the materials listed as solid electrolytes. For example, the electrolyte layer 30 may contain a halide solid electrolyte and a sulfide solid electrolyte.

[0171] The thickness of the electrolyte layer 30 may be between 1 μm and 300 μm. When the thickness of the electrolyte layer 30 is 1 μm or more, the possibility of a short circuit between the positive electrode 20 and the negative electrode 40 is reduced. When the thickness of the electrolyte layer 30 is 300 μm or less, the battery 200 can be easily operated at high power. In other words, if the thickness of the electrolyte layer 30 is appropriately adjusted, the safety of the battery 200 can be sufficiently ensured, and the battery 200 can be operated at high power.

[0172] The shape of the solid electrolyte contained in battery 200 is not particularly limited. The solid electrolyte may be needle-shaped, spherical, ellipsoidal, or the like. The solid electrolyte may also be particulate.

[0173] The positive electrode 20 may contain an electrolyte material, for example, a solid electrolyte. As the solid electrolyte, the solid electrolyte exemplified as the material constituting the electrolyte layer 30 can be used. With the above configuration, the ion conductivity (e.g., lithium ion conductivity) inside the positive electrode 20 is improved, and the battery 200 can operate at high power.

[0174] In the positive electrode 20, a sulfide solid electrolyte may be used as the solid electrolyte, and the above-mentioned halogen solid electrolyte may be used as the coating material for coating the active material.

[0175] The positive electrode 20 includes, for example, a material having the property of intercalating and releasing metal ions (e.g., lithium ions) as the positive electrode active material. The material exemplified in Embodiment 1 described above may be used as the positive electrode active material.

[0176] The median diameter of the positive electrode active material may be between 0.1 μm and 100 μm. When the median diameter of the positive electrode active material is 0.1 μm or more, the positive electrode active material and the solid electrolyte can be well dispersed in the positive electrode 20. This improves the charge and discharge characteristics of the battery 200. When the median diameter of the positive electrode active material is 100 μm or less, the lithium diffusion rate within the positive electrode active material improves. Therefore, the battery 200 can operate at high power.

[0177] The median diameter of the positive electrode active material may be larger than the median diameter of the solid electrolyte. This allows for good dispersion of the solid electrolyte and the positive electrode active material.

[0178] In the positive electrode 20, the volume ratio of the positive electrode active material to the solid electrolyte "v2:100-v2" may satisfy the condition 30≦v2≦95. v2 represents the volume ratio of the positive electrode active material when the total volume of the positive electrode active material and solid electrolyte contained in the positive electrode 20 is set to 100. If 30≦v2 is satisfied, it is easier to ensure a sufficient energy density for the battery 200. If v2≦95 is satisfied, it is easier to operate the battery 200 at a high power output.

[0179] The thickness of the positive electrode 20 may be between 10 μm and 500 μm. When the thickness of the positive electrode 20 is 10 μm or more, a sufficient energy density can be easily ensured for the battery 200. When the thickness of the positive electrode 20 is 500 μm or less, the battery 200 can be operated at a higher power output more easily.

[0180] The positive electrode active material may be coated with a coating material to reduce interfacial resistance with the solid electrolyte. A material with low electronic conductivity may be used as the coating material. Examples of coating materials include oxide materials and oxide solid electrolytes. The materials exemplified in Embodiment 1 described above may also be used as the coating material.

[0181] The positive electrode 20 may contain a conductive additive to improve electronic conductivity. The materials exemplified in Embodiment 1 described above may be used as the conductive additive. Using a carbon material as the conductive additive can reduce costs.

[0182] The negative electrode 40 includes, for example, an active material 10, conductive fibers 11, a binder 12, and a solid electrolyte 13. The thickness of the negative electrode 40 may be between 10 μm and 500 μm. When the thickness of the negative electrode 40 is 10 μm or more, a sufficient energy density can be easily ensured for the battery 200. When the thickness of the negative electrode 40 is 500 μm or less, the battery 200 can be operated at a higher power more easily.

[0183] At least one selected from the group consisting of the positive electrode 20 and the electrolyte layer 30 may contain a binder for the purpose of improving the adhesion between particles. As the binder, the material exemplified in Embodiment 1 described above may be used.

[0184] At least one selected from the group consisting of the positive electrode 20, the electrolyte layer 30, and the negative electrode 40 may contain a non-aqueous electrolyte, a gel electrolyte, or an ionic liquid for the purpose of facilitating the transfer of lithium ions and improving the output characteristics of the battery 200.

[0185] The non-aqueous electrolyte contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent. Possible non-aqueous solvents include cyclic carbonate solvents, linear carbonate solvents, cyclic ether solvents, linear ether solvents, cyclic ester solvents, linear ester solvents, and fluorine solvents. Examples of cyclic carbonate solvents include ethylene carbonate, propylene carbonate, and butylene carbonate. Examples of linear carbonate solvents include dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. Examples of cyclic ether solvents include tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane. Examples of linear ether solvents include 1,2-dimethoxyethane and 1,2-diethoxyethane. Examples of cyclic ester solvents include γ-butyrolactone. Examples of linear ester solvents include methyl acetate. Examples of fluorinated solvents include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, and fluorodimethylene carbonate. As a non-aqueous solvent, one non-aqueous solvent selected from these may be used alone, or a mixture of two or more non-aqueous solvents selected from these may be used.

[0186] The non-aqueous electrolyte may contain at least one fluorine solvent selected from the group consisting of fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, and fluorodimethylene carbonate.

[0187] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), and LiC(SO2CF3)3. One lithium salt selected from these may be used alone, or a mixture of two or more lithium salts selected from these may be used. The concentration of the lithium salt in the non-aqueous electrolyte may be 0.5 mol / liter or more and 2 mol / liter or less.

[0188] As the gel electrolyte, a material containing a non-aqueous electrolyte in a polymer material can be used. Examples of polymer materials include polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, and polymers having ethylene oxide bonds.

[0189] The cations constituting the ionic liquid may include aliphatic quaternary cations such as tetraalkylammonium and tetraalkylphosphonium, aliphatic cyclic ammonium compounds such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperadiniums, and piperidiniums, and nitrogen-containing heterocyclic aromatic cations such as pyridiniums and imidazoliums. The anions constituting the ionic liquid are PF6. - BF4 - SbF6 - AsF6 - , SO3CF3 - , N(SO2F)2 - , N(SO2CF3)2 - , N(SO2C2F5)2 - , N(SO2CF3)(SO2C4F9) - , C(SO2CF3)3 - Other examples are also acceptable. The ionic liquid may contain a lithium salt.

[0190] The shapes of the 200 battery include coin-type, cylindrical, rectangular, sheet-type, button-type, flat, and stacked types.

[0191] The battery 200 in Embodiment 2 can be manufactured, for example, by the following method. First, a current collector for the positive electrode 20, a material for forming the positive electrode 20, a material for forming the electrolyte layer 30, a material for forming the negative electrode 40, and a current collector for the negative electrode 40 are prepared. The material for forming the negative electrode 40 is, for example, the electrode material 100 of Embodiment 1. Using these, a laminate is fabricated in which the positive electrode 20, the electrolyte layer 30, and the negative electrode 40 are arranged in this order by a known method. This allows the battery 200 to be manufactured. [Examples]

[0192] The details of this disclosure will be explained below using examples and comparative examples. However, the electrodes and batteries of this disclosure are not limited to the following examples.

[0193] (Comparative Example 1) First, carbon nanotubes (CNTs) (VGCF-H) with an average fiber diameter of 150 nm were prepared as conductive fibers. Styrene-butadiene random copolymer (SBR) (Tuffden® 2100R, manufactured by Asahi Kasei Corporation) was prepared as a binder. Tetralin was prepared as a solvent. Under conditions of 25°C, the CNTs, binder, and solvent were mixed in the following mass ratios. Specifically, these materials were mixed by adding the conductive fibers to a solution obtained by dissolving the binder in the solvent. This yielded the slurry of Comparative Example 1. In the obtained slurry, the ratio of the binder's mass to the mass of the CNTs was 5% by mass.

[0194] <Mass ratio> CNT: 10% by mass Binder: 0.50% by mass Solvent: 89.50% by mass

[0195] (Comparative Examples 2 to 3 and Examples 1 to 9) The slurries of Comparative Examples 2 to 3 and Examples 1 to 9 were obtained by the same method as for Comparative Example 1, except that the binders listed in Table 1 were used.

[0196] [Evaluation of Styrene Ratio] Regarding the elastomer that makes up the binder, 1 The styrene ratio was measured by 1H NMR. The sample used was an elastomer dissolved in CDCl3. The CDCl3 contained 0.05% TMS. 11H NMR measurement was performed under the condition of a resonance frequency of 500 MHz. From the obtained NMR spectrum, the integrated value of the peak derived from the styrene skeleton and the integrated value of the peak derived from skeletons other than the styrene skeleton were identified. The styrene content ratio of the elastomer was identified using the identified integrated values.

[0197] [Evaluation of Slurry] For the slurries of Comparative Examples 1 to 3 and Examples 1 to 9, the dispersibility of CNTs was evaluated by the following method. First, the prepared slurry was applied onto a glass substrate using an applicator, with the gap set to 100 μm at this time. Next, the obtained coating film was dried by heating on a hot plate heated to 100°C for 10 minutes. The surface of the obtained dried film was observed in 3 fields of view at a magnification of 50× using a laser microscope. The surface roughness (arithmetic mean height Sa) of the dried film in each field of view was measured, and the average value thereof was calculated. The dispersibility of CNTs in the slurry was evaluated based on this average Sa value. The results are shown in Table 1. In Table 1, a circle (○) means that the condition average Sa ≤ 1.5 μm is satisfied. A triangle (△) means that the condition 1.5 μm < average Sa ≤ 2.2 μm is satisfied. A cross (×) means that the condition 2.2 μm < average Sa is satisfied.

[0198]

Table 1

[0199] In Table 1, the details of binder types A to L are as follows. A: Styrene-butadiene random copolymer (SBR) (Toughden (registered trademark) 2100R manufactured by Asahi Kasei Corporation) B: Styrene-butadiene-styrene block copolymer (SBS) (Asaprene (registered trademark) T-411 manufactured by Asahi Kasei Corporation) C: Styrene-ethylene / butylene-styrene block copolymer (SEBS) (Tuftec (registered trademark) H1221 manufactured by Asahi Kasei Corporation) D: Hydrogenated styrene-butadiene random copolymer (SBR) (Dynalon® 2324P, manufactured by JSR Corporation) E: Styrene-butadiene / butylene-styrene block copolymer (SBBS) (ToughTec® P1500 manufactured by Asahi Kasei Corporation) F:SEBS (ToughTec® H1052 manufactured by Asahi Kasei Corporation) G:SEBS (ToughTec® H1053 manufactured by Asahi Kasei Corporation) H:SEBS (ToughTec® H1051 manufactured by Asahi Kasei Corporation) I: SEBS (ToughTec® N504 manufactured by Asahi Kasei Corporation) J: Modified SEBS (ToughTec® M1913 manufactured by Asahi Kasei Corporation) K: Styrene-ethylene / ethylene / propylene-styrene block copolymer (SEEPS) (Septon® 4055, manufactured by Kuraray Co., Ltd.) L:SEEPS (Septon® 4099, manufactured by Kuraray Co., Ltd.)

[0200] As can be seen from Table 1, the dried films formed from the slurries of the examples had a smaller arithmetic mean surface height Sa compared to the comparative example. This indicates that the aggregation of conductive fibers was suppressed and the dispersibility was improved in the slurries of the examples compared to the comparative example. In other words, the results of the examples show that the dispersibility of conductive fibers is improved when the elastomer of this embodiment is used as a binder. In particular, the slurries of Examples 3 to 9, which contained SEBS or SEEPS with a styrene-derived repeating unit content of 15% by mass or more, showed even greater dispersibility of conductive fibers.

[0201] (Comparative Example 4) The electrode material of Comparative Example 4 was prepared by the method shown in Figure 9. Figure 9 is a flowchart of the method for producing the electrode material of Comparative Example 4. In detail, first, in step S51, the active material and solvent were mixed. Si was used as the active material. Tetralin was used as the solvent. Next, in step S52, the obtained mixture was subjected to a dispersion treatment. The dispersion treatment was carried out for 30 minutes using a high-speed homogenizer. A slurry was obtained by the dispersion treatment in step S52 (step S53).

[0202] Next, in step S54, the slurry and conductive fibers were mixed. As the conductive fibers, CNTs (VGCF-H) with an average fiber diameter of 150 nm were used. Next, in step S55, the obtained mixture was further mixed with a solid electrolyte. As the solid electrolyte, a sulfide solid electrolyte Li2S-P2S5 was used. Next, in step S56, the mixture obtained in step S55 was subjected to a dispersion treatment. The dispersion treatment was carried out for 30 minutes using a high-speed homogenizer. This yielded the electrode material for Comparative Example 4 (step S57).

[0203] (Example 10) The electrode material for Example 10 was prepared by the method shown in Figure 3. First, in step S01, the conductive fibers, binder, and solvent were mixed. Specifically, these materials were mixed by adding the conductive fibers to a solution obtained by dissolving the binder in the solvent. The same conductive fibers and solvent as in Comparative Example 4 were used. SEBS (ToughTec N504, manufactured by Asahi Kasei Corporation) was used as the binder. In step S02, a first slurry was prepared by performing a dispersion treatment on the obtained mixture (step S03). The dispersion treatment was performed for 2 minutes using an ultrasonic homogenizer.

[0204] Next, in step S04, the active material and solvent were mixed. The same active material and solvent as in Comparative Example 4 were used. In step S05, a second slurry was prepared by dispersing the resulting mixture (step S06). The dispersion treatment was carried out for 30 minutes using a high-speed homogenizer.

[0205] Next, in step S07, the first slurry, the second slurry, and the solid electrolyte were mixed. The same solid electrolyte as in Comparative Example 4 was used. Next, in step S08, the mixture obtained in step S07 was subjected to a dispersion treatment. The dispersion treatment was carried out for 30 minutes using a high-speed homogenizer. This yielded the electrode material of Example 10 (step S09).

[0206] (Example 11) The electrode material for Example 11 was obtained by the same method as in Example 10, except that SEBS (ToughTec H1051 manufactured by Asahi Kasei Corporation) was used as the binder.

[0207] [Measurement of electronic conductivity] The electron conductivity of the electrode materials of Comparative Example 4 and Examples 10 to 11 was measured by the following method. First, the electrode material was coated onto a current collector. By drying the resulting coating film, an active material layer was formed, and an electrode was obtained. Next, the electrodes were pressure-restrained by applying a pressure of 2 N·m to the opposing main surfaces of the electrodes. Then, a voltage was applied to the electrodes, and the current value at this time was measured. In detail, the applied voltage was set to 0.5 V, 1.0 V, and 2.0 V, and the current value at each voltage value was measured. The three obtained data points were plotted on a graph, and an approximate straight line was created. Based on the slope of the approximate straight line, the resistance value of the electrode was calculated. From this calculated value, the electron conductivity of the electrode was obtained. The results are shown in Table 2. The electron conductivity in Table 2 corresponds to the value when the electron conductivity measured in Comparative Example 4 is set to 100.

[0208] [Table 2]

[0209] As can be seen from Table 2, the electrode materials of Examples 10 and 11 showed an increase in electronic conductivity of approximately 1.5 times or more compared to Comparative Example 4. This is presumed to be due to the improved dispersibility of conductive fibers in the electrode material by using the elastomer of this embodiment as a binder.

[0210] (Comparative Example 5) The electrode material for Comparative Example 5 was obtained by the same method as for Comparative Example 4, except that CNTs (TUBALL manufactured by OCSiAl) with an average fiber diameter of 1.5 nm were used as conductive fibers.

[0211] (Example 12) The electrode material for Example 12 was obtained by the same method as in Example 10, except that CNTs with an average fiber diameter of 1.5 nm were used as conductive fibers.

[0212] (Example 13) The electrode material of Example 13 was obtained by the same method as in Example 11, except that CNTs with an average fiber diameter of 1.5 nm were used as conductive fibers.

[0213] [Measurement of electronic conductivity] The electron conductivity of the electrode materials of Comparative Example 5 and Examples 12 to 13 was measured using the method described above. The results are shown in Table 3. The electron conductivity values ​​in Table 3 correspond to the values ​​when the electron conductivity measured in Comparative Example 5 is set to 100.

[0214] [Table 3]

[0215] As can be seen from Table 3, the electrode materials of Examples 12 and 13 showed increased electronic conductivity compared to Comparative Example 5. This is presumed to be due to the improved dispersibility of conductive fibers in the electrode material by using the elastomer of this embodiment as a binder.

[0216] Tables 2 and 3 show that the electrode material of this embodiment is suitable for fabricating electrodes with improved electronic conductivity. In particular, Tables 2 and 3 indicate that elastomers with a high content of repeating units derived from styrene are suitable for improving the electronic conductivity of electrodes. [Industrial applicability]

[0217] The electrode material of this disclosure can be used, for example, in all-solid-state lithium-ion secondary batteries. Batteries equipped with electrodes formed from this electrode material tend to have not only high energy density but also excellent cycle characteristics. [Explanation of Symbols]

[0218] 10 Active material 11 Conductive Fibers 12 Binders 13 Solid electrolyte 14 Solvents 20 positive electrode 30 Electrolyte layer 40 negative electrode 100 Electrode materials 200 batteries

Claims

1. Active material and, Conductive fibers containing carbon material, A binder containing elastomer, Includes, The conductive fiber contains carbon nanotubes, The elastomer is a hydrogenated material and contains repeating units having an aromatic ring. The content of the repeating units in the elastomer is 40% by mass or more. The elastomer comprises at least one selected from the group consisting of styrene-ethylene / butylene-styrene block copolymer (SEBS) and styrene-ethylene / ethylene / propylene-styrene block copolymer (SEEPS). electrode material.

2. The average fiber diameter of the conductive fibers is 300 nm or less. The electrode material according to claim 1.

3. The hydrogenation rate of the elastomer is 90% or more. The electrode material according to claim 1 or 2.

4. Further containing a solid electrolyte, The electrode material according to any one of claims 1 to 3.

5. The solid electrolyte has lithium ion conductivity. The electrode material according to claim 4.

6. Further containing a solvent, The electrode material according to any one of claims 1 to 5.

7. A method for manufacturing an electrode material according to any one of claims 1 to 6, The aforementioned manufacturing method is This includes preparing a slurry containing the conductive fibers and the binder. A method for manufacturing electrode materials.

8. The process further includes mixing the slurry containing the conductive fibers and the binder with a slurry containing at least one selected from the group consisting of an active material and a solid electrolyte. The manufacturing method according to claim 7.

9. Positive electrode and, The negative electrode and, An electrolyte layer located between the positive electrode and the negative electrode, Equipped with, At least one selected from the group consisting of the positive electrode and the negative electrode comprises an active material, conductive fibers containing a carbon material, and a binder containing an elastomer. The conductive fiber contains carbon nanotubes, The elastomer is a hydrogenated material and contains repeating units having an aromatic ring. The content of the repeating units in the elastomer is 40% by mass or more. The elastomer comprises at least one selected from the group consisting of styrene-ethylene / butylene-styrene block copolymer (SEBS) and styrene-ethylene / ethylene / propylene-styrene block copolymer (SEEPS). battery.

10. The electrolyte layer includes a solid electrolyte. The battery according to claim 9.

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