Evaluation method and production method for slurry for batteries, method for producing battery, and slurry for batteries

Abstract

To provide: an evaluation method and production method for a slurry for batteries designed to obtain a coated film with satisfactory properties; a method for producing a battery that includes producing the slurry for batteries; and a slurry for batteries that can yield a coated film with satisfactory properties.SOLUTION: A method of the present disclosure for evaluating a slurry for batteries includes measuring a relaxation time of the slurry using a TDNMR apparatus to evaluate dispersity of specific components. A method of the present disclosure for producing the slurry of the batteries includes evaluating a disperse medium of certain ingredients in the method of the present disclosure for evaluating the slurry of the battery. A method of the present disclosure for evaluating the dispersity of the specific component. manufacturing the battery includes a step of providing the slurry of the battery in the method of the present disclosure for manufacturing the slurry of the battery. In the slurry of the battery of the present disclosure, a conversion value calculated based on the relaxation time, of a dispersion medium when the relaxation time is measured by a predetermined method using the TDNMR apparatus, is within a predetermined range.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for evaluating and producing a battery slurry, a method for producing a battery, and a battery slurry. [Background technology]

[0002] As disclosed in Patent Document 1, a technique is known for measuring the degree of dispersion of components contained in a slurry composition for a solid battery by a particle gauge method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 241322 Summary of the Invention [Problem to be solved by the invention]

[0004] In manufacturing a battery, it is preferable to be able to predict the properties of a coating film obtained by coating and drying a battery slurry based on the properties of the battery slurry. The present inventors have found that even if the dispersion degree of components in a battery slurry measured by a particle gauge method is equal to or less than a threshold, coarse particles may remain in the coating film, i.e., the properties of the coating film may be poor.

[0005] The present disclosure aims to provide a method for evaluating and producing a battery slurry for obtaining a coating film with good properties, a method for producing a battery that includes producing such a battery slurry, and a battery slurry that can obtain a coating film with good properties. [Means for solving the problem]

[0006] The present inventors have found that the above problems can be solved by the following means. <Aspect 1> A method for evaluating a battery slurry, comprising: measuring a relaxation time of the battery slurry using a time-domain nuclear magnetic resonance spectrometer, thereby evaluating a degree of dispersion of a specific component contained in the battery slurry. <Aspect 2> 2. The method of claim 1, wherein the battery slurry is a negative electrode mixture slurry and the specific component is a negative electrode active material. <Aspect 3> The method of embodiment 2, wherein the relaxation time is measured by a CPMG method. <Aspect 4> A method for producing a negative electrode mixture slurry, comprising the following steps: (a) providing a preliminary negative electrode mixture slurry containing a negative electrode active material and a dispersion medium; (b) stirring the preliminary negative electrode composite slurry; and (c) Evaluating the degree of dispersion of the negative electrode active material contained in the negative electrode mixture slurry by the method described in aspect 2. <Aspect 5> the step (c) repeats steps (b) and (c) until a converted value of the relaxation time of the negative electrode composite slurry measured by a CPMG method, calculated based on the relaxation time of the dispersion medium, is equal to or greater than 0.015 and equal to or less than 0.025. <Aspect 6> 5. The method of claim 4, wherein the negative electrode active material has an average particle size of 10 nm or more and 50 μm or less. <Aspect 7> A method for manufacturing a battery, comprising the steps of: Providing a negative electrode mixture slurry by the method according to any one of aspects 4 to 6; and The negative electrode mixture slurry is applied to a substrate, and the dispersion medium is then dried and removed to form a negative electrode active material layer. <Aspect 8> A negative electrode composite slurry, in which, when measured by a CPMG method using a time-domain nuclear magnetic resonance spectrometer, the converted value of the relaxation time calculated based on the relaxation time of the dispersion medium is 0.015 or more and 0.025 or less. <Aspect 9> 2. The method of claim 1, wherein the battery slurry is a solid electrolyte mixture slurry and the particular component is a solid electrolyte. <Aspect 10> The method of embodiment 9, wherein the relaxation time is measured by a CPMG method. <Aspect 11> A method for producing a solid electrolyte composite slurry, comprising the steps of: (a) providing a preliminary solid electrolyte mixture slurry including a solid electrolyte and a dispersion medium; (b) stirring the preliminary solid electrolyte mixture slurry; and (c) Evaluating the degree of dispersion of the solid electrolyte contained in the solid electrolyte mixture slurry by the method described in aspect 9. <Aspect 12> Aspect 12. The method of aspect 11, wherein in the step (c), steps (b) and (c) are repeated until a converted value of the relaxation time of the solid electrolyte mixture slurry measured by a CPMG method, calculated based on the relaxation time of the dispersion medium, is 0.45 or more and 0.50 or less. <Aspect 13> 12. The method of claim 11, wherein the solid electrolyte has an average particle size of 1 nm or more and 10 μm or less. <Aspect 14> A method for manufacturing a battery, comprising the steps of: Providing a solid electrolyte mixture slurry by the method according to any one of aspects 11 to 13; and The solid electrolyte mixture slurry is applied to a substrate, and the dispersion medium is then dried and removed to form a solid electrolyte layer. <Aspect 15> A solid electrolyte composite slurry, wherein a conversion value of a relaxation time calculated based on the relaxation time of a dispersion medium is 0.45 or more and 0.50 or less when measured by a CPMG method using a time-domain nuclear magnetic resonance spectrometer. <Aspect 16> 2. The method of claim 1, wherein the battery slurry is a cathode mixture slurry and the specific component is a cathode active material. <Aspect 17> 17. The method of embodiment 16, wherein the relaxation time is measured by a solid echo method. <Aspect 18> A method for producing a cathode mixture slurry, comprising the steps of: (a) providing a preliminary positive electrode mixture slurry containing a positive electrode active material and a dispersion medium; (b) stirring the preliminary cathode composite slurry; and (c) Evaluating the degree of dispersion of the positive electrode active material contained in the positive electrode mixture slurry by the method according to aspect 16. <Aspect 19> In the step (c), the relaxation time of the positive electrode composite slurry measured by a solid echo method is converted into a value calculated based on the relaxation time of the dispersion medium of 4.5 × 10 -5 Over 5.4 x 10 -5 20. The method of embodiment 18, wherein steps (b) and (c) are repeated until: <Aspect 20> 19. The method of claim 18, wherein the positive electrode active material has an average particle size of 10 nm or more and 50 μm or less. <Aspect 21> A method for manufacturing a battery, comprising the steps of: Providing a positive electrode mixture slurry by the method according to any one of aspects 18 to 20; and The positive electrode mixture slurry is applied to a substrate, and the dispersion medium is then dried and removed to form a positive electrode active material layer. <Aspect 22> When measured by the solid echo method using a time-domain nuclear magnetic resonance spectrometer, the conversion value of the relaxation time calculated based on the relaxation time of the dispersion medium was 4.5 x 10 -5 Over 5.4 x 10 -5 The positive electrode mixture slurry is as follows: [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a method for evaluating and producing a battery slurry for obtaining a coating film with good properties, a method for producing a battery that includes producing such a battery slurry, and a battery slurry that can obtain a coating film with good properties. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described in detail. Note that the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the present disclosure.

[0009] As described above, the present inventors have found that even if the degree of dispersion of components in a battery slurry measured by the particle gauge method is below a threshold value, coarse particles may remain in the coating film, i.e., the properties of the coating film may not be good.

[0010] In this regard, the present inventors have considered that one of the reasons why the properties of a coating film may be poor even when the dispersity measured by the particle gauge method is below a threshold is due to the mechanical force applied to the slurry when measuring by the particle gauge method. Specifically, without intending to be bound by any theory, this is presumed as follows: Measurement by the particle gauge method involves a process of dragging a scraper over a grind gauge filled with slurry. The shear force applied to the slurry during this process causes deformation and deagglomeration of the components contained in the slurry, making it impossible to accurately measure the dispersity of the components in the slurry and therefore impossible to accurately predict the properties of the resulting coating film. In other words, in battery slurries, even aggregates that easily deform and deagglomerate due to shear during measurement by the particle gauge method are thought to affect the properties of the resulting active material layer, etc.

[0011] In this regard, the present inventors employed the relaxation time measured using a time-domain nuclear magnetic resonance (TDNMR) device as an indicator of the degree of dispersion of a specific component in a slurry and found that if this relaxation time is within a predetermined range, the coating film has good properties. Without intending to be bound by any theory, the reason for this is presumed to be as follows. Specifically, unlike measurements using a particle gauge method, measurements using a TDNMR device do not apply excessively strong mechanical forces to the slurry. Therefore, it is believed that deformation and deagglomeration of the components contained in the slurry can be suppressed, and as a result, the degree of dispersion of the components in the slurry can be accurately evaluated. Furthermore, it is believed that accurately evaluating the degree of dispersion of the components in a battery slurry in this way allows accurate prediction of the properties of the resulting active material layer, etc.

[0012] In the context of this disclosure, "relaxation time" means the transverse relaxation time (spin-spin relaxation time), T2.

[0013] In accordance with the present disclosure, the degree of dispersion of particles, which are specific components in a battery slurry, can be evaluated based on the mobility of solvent molecules. That is, when there are many solvent molecules bound to particles, the measured relaxation time (T2) is short, indicating a high degree of dispersion. On the other hand, when there are more free solvent molecules than those bound to particles, the measured relaxation time (T2) is long, indicating a low degree of dispersion. Therefore, differences in the degree of dispersion of particles in a slurry can be indicated by the length of the relaxation time (T2).

[0014] In the present disclosure, the term "battery slurry" is used as a general term for negative electrode composite slurry, solid electrolyte composite slurry, and positive electrode composite slurry.

[0015] <<Method for Evaluating Negative Electrode Composite Slurry>> The method for evaluating a negative electrode composite slurry disclosed herein includes evaluating the degree of dispersion of the negative electrode active material contained in the negative electrode composite slurry by measuring the relaxation time of the negative electrode composite slurry using a time-domain nuclear magnetic resonance (TDNMR) device, thereby enabling accurate evaluation of the degree of dispersion of the negative electrode active material contained in the negative electrode composite slurry.

[0016] In the method of the present disclosure, for example, a Minispec mq20 manufactured by Bruker can be used as the TDNMR instrument. Furthermore, the converted value of the relaxation time can be calculated using the data analysis software TDNMR-A provided with the TDNMR instrument. Specifically, the converted value can be obtained by calculating the ratio of the relaxation time of the negative electrode composite slurry to the relaxation time of the dispersion medium used to prepare the negative electrode composite slurry. This also applies to the other battery slurry evaluation methods of the present disclosure.

[0017] In the method of the present disclosure, the relaxation time may be measured by the CPMG method, which refers to a method in which a 90° pulse is first applied to generate transverse magnetization, which is then relaxed during τ, and a 180° pulse is subsequently applied to invert the phase, generating a resonance signal echo, and the signal intensity is measured.

[0018] <<Method for producing negative electrode composite slurry>> The disclosed method for producing a negative electrode composite slurry includes the following steps: (a) providing a preliminary negative electrode composite slurry containing a negative electrode active material and a dispersion medium, (b) stirring the preliminary negative electrode composite slurry, and (c) evaluating the degree of dispersion of the negative electrode active material contained in the negative electrode composite slurry using the disclosed method for evaluating a negative electrode composite slurry. By including the step of evaluating the degree of dispersion of the negative electrode active material contained in the negative electrode composite slurry using the disclosed method for evaluating a negative electrode composite slurry, a coating film with good properties can be obtained when the produced negative electrode composite slurry is used to form a coating film.

[0019] <Preliminary negative electrode composite slurry providing step> The disclosed method for producing a negative electrode mixture slurry includes (a) providing a preliminary negative electrode mixture slurry including a negative electrode active material and a dispersion medium.

[0020] (Negative electrode active material) As the negative electrode active material, a material exhibiting a lower potential than the positive electrode active material can be used. As such a negative electrode active material, a known active material may be used. For example, in the case of constructing a lithium ion battery, the negative electrode active material may be a silicon-based active material such as silicon, a silicon alloy, or silicon oxide; a carbon-based active material such as graphite or hard carbon; various oxide-based active materials such as lithium titanate; metallic lithium or a lithium alloy; etc.

[0021] The average particle size of the negative electrode active material may be 10 nm or more and 50 μm or less. The average particle size of the negative electrode active material may be 100 nm or more or 500 nm or more, and may be 30 μm or less or 10 μm or less. The average particle size of the negative electrode active material can be determined, for example, as the average circle-equivalent diameter of the negative electrode active material in a scanning electron microscope (SEM) image. The average particle size of the solid electrolyte and positive electrode active material described below can also be measured in a similar manner.

[0022] (dispersion medium) Examples of the dispersion medium include non-polar solvents, polar solvents, and combinations thereof. Examples of non-polar solvents include heptane, xylene, toluene, and combinations thereof. Examples of polar solvents include tertiary amine solvents such as triethylamine, ether solvents such as cyclopentyl methyl ether, thiol solvents such as ethane mercaptan, ester solvents such as butyl butyrate, and combinations thereof.

[0023] <Preliminary Negative Electrode Composite Slurry Stirring Step> The method of the present disclosure includes (b) stirring the preliminary negative electrode mix slurry.

[0024] The method for stirring the preliminary negative electrode composite slurry is not particularly limited, and examples thereof include a method of mixing using an ultrasonic disperser, a method of mixing using a stirring blade, or a method of mixing using a combination of these. This method can also be applied to other battery slurry manufacturing methods in the present disclosure.

[0025] <Evaluation process> The disclosed method for producing a negative electrode mixture slurry includes (c) evaluating the degree of dispersion of the negative electrode active material contained in the negative electrode mixture slurry by the disclosed method for evaluating a negative electrode mixture slurry.

[0026] For the method of evaluating the negative electrode mixture slurry of the present disclosure, reference can be made to the above description of the method of evaluating the negative electrode mixture slurry of the present disclosure.

[0027] In the method of the present disclosure for producing a negative electrode composite slurry, in step (c), steps (b) and (c) may be repeated until a converted value of the relaxation time of the negative electrode composite slurry measured by the CPMG method, calculated based on the relaxation time of the dispersion medium, is 0.015 or more and 0.025 or less.

[0028] <Negative electrode mixture slurry> When the negative electrode composite slurry of the present disclosure is measured by the CPMG method using a time-domain nuclear magnetic resonance spectrometer, the converted value of the relaxation time calculated based on the relaxation time of the dispersion medium is 0.015 or more and 0.025 or less.

[0029] The converted value may be 0.015 or more, 0.016 or more, 0.017 or more, or 0.018 or more, and may be 0.025 or less. When the converted value is within the above range, a coating film with good properties can be obtained.

[0030] <<Evaluation method for solid electrolyte composite slurry>> The method for evaluating a solid electrolyte mixture slurry according to the present disclosure includes evaluating the degree of dispersion of a solid electrolyte contained in the solid electrolyte mixture slurry by measuring the relaxation time of the solid electrolyte mixture slurry using a time-domain nuclear magnetic resonance spectrometer, thereby enabling accurate evaluation of the degree of dispersion of the solid electrolyte contained in the solid electrolyte mixture slurry.

[0031] In the method of evaluating a solid electrolyte mixture slurry according to the present disclosure, the relaxation time may be measured by the CPMG method. For the CPMG method, reference can be made to the above description of the method of evaluating a negative electrode mixture slurry according to the present disclosure.

[0032] <<Method for producing solid electrolyte composite slurry>> The disclosed method for producing a solid electrolyte mixture slurry includes the following steps: (a) providing a preliminary solid electrolyte mixture slurry containing a solid electrolyte and a dispersion medium, (b) stirring the preliminary solid electrolyte mixture slurry, and (c) evaluating the degree of dispersion of the solid electrolyte contained in the solid electrolyte mixture slurry using the disclosed method for evaluating a solid electrolyte mixture slurry. By including the step of evaluating the degree of dispersion of the solid electrolyte contained in the solid electrolyte mixture slurry using the disclosed method for evaluating a solid electrolyte mixture slurry, a coating film with good properties can be obtained when the produced solid electrolyte mixture slurry is used to form a coating film.

[0033] <Preliminary solid electrolyte composite slurry providing step> The disclosed method for producing a solid electrolyte mixture slurry includes (a) providing a preliminary solid electrolyte mixture slurry including a solid electrolyte and a carrier medium.

[0034] (solid electrolyte) The material of the solid electrolyte is not particularly limited, and may be, for example, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer electrolyte, or the like.

[0035] Examples of sulfide solid electrolytes include, but are not limited to, sulfide-based amorphous solid electrolytes, sulfide-based crystalline solid electrolytes, and argyrodite-type solid electrolytes. Specific examples of sulfide solid electrolytes include Li2S-P2S5-based (Li7P3S 11 , Li3PS4, Li8P2S9, etc.), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-P2S5-GeS2(Li 13 GeP3S 16 , Li 10 GeP2S 12 ), LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 7-x PS 6-x Cl x etc.; or combinations thereof, but are not limited to these.

[0036] An example of an oxide solid electrolyte is Li7La3Zr2O 12 , Li 7-x La3Zr 1-x Nb x O 12 , Li 7-3x La3Zr2Al x O 12 , Li 3x La 2 / 3-x TiO3, Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Al x Ge 2-x (PO4)3, Li3PO4, or Li 3+x PO 4-x N x (LiPON), etc., but are not limited to these.

[0037] The sulfide solid electrolyte and the oxide solid electrolyte may be glass or crystallized glass (glass ceramics).

[0038] Examples of polymer electrolytes include, but are not limited to, polyethylene oxide (PEO), polypropylene oxide (PPO), copolymers thereof, and the like.

[0039] The average particle size of the solid electrolyte may be 1 nm or more and 10 μm or less. The average particle size of the solid electrolyte may be 10 nm or more, or 100 nm or more, and may be 5 μm or less, or 3 μm or less.

[0040] (dispersion medium) For the dispersion medium, reference can be made to the above description regarding the method for producing the negative electrode mixture slurry of the present disclosure.

[0041] <Preliminary solid electrolyte composite slurry stirring step> The disclosed method of producing a solid electrolyte mixture slurry includes (b) stirring the preliminary solid electrolyte mixture slurry.

[0042] <Evaluation process> The disclosed method for producing a solid electrolyte mixture slurry includes (c) evaluating the degree of dispersion of the solid electrolyte contained in the solid electrolyte mixture slurry by the disclosed method for evaluating a solid electrolyte mixture slurry.

[0043] For the method of evaluating a solid electrolyte mixture slurry according to the present disclosure, reference can be made to the above description of the method of evaluating a solid electrolyte mixture slurry according to the present disclosure.

[0044] In the method for producing a solid electrolyte mixture slurry according to the present disclosure, in step (c), steps (b) and (c) may be repeated until a converted value of the relaxation time of the solid electrolyte mixture slurry measured by the CPMG method, calculated based on the relaxation time of the dispersion medium, is 0.45 or more and 0.50 or less.

[0045] <Solid electrolyte composite slurry> When the solid electrolyte composite slurry of the present disclosure is measured by the CPMG method using a time-domain nuclear magnetic resonance spectrometer, the converted value of the relaxation time calculated based on the relaxation time of the dispersion medium is 0.45 or more and 0.50 or less.

[0046] The converted value may be 0.45 or more, or 0.46 or more, and may be 0.50 or less, or 0.49 or less. When the converted value is within the above range, a coating film with good properties can be obtained.

[0047] <<Evaluation method for cathode composite slurry>> The method for evaluating a positive electrode composite slurry according to the present disclosure includes evaluating the degree of dispersion of the positive electrode active material contained in the positive electrode composite slurry by measuring the relaxation time of the positive electrode composite slurry using a time-domain nuclear magnetic resonance spectrometer, thereby enabling accurate evaluation of the degree of dispersion of the positive electrode active material contained in the positive electrode composite slurry.

[0048] The method for evaluating the positive electrode composite slurry according to the present disclosure may measure the relaxation time by a solid echo method. In the present disclosure, the solid echo method refers to a method in which a 90° pulse is first applied to create transverse magnetization, and then a second 90° pulse is applied with a phase shift of 90° to generate an echo, thereby measuring the signal intensity, in order to apparently eliminate time that cannot be observed by the measurement device.

[0049] <<Method for producing positive electrode composite slurry>> The disclosed method for producing a positive electrode mixture slurry includes the following steps: (a) providing a preliminary positive electrode mixture slurry containing a positive electrode active material and a dispersion medium, (b) stirring the preliminary positive electrode mixture slurry, and (c) evaluating the degree of dispersion of the positive electrode active material contained in the positive electrode mixture slurry using the disclosed method for evaluating a positive electrode mixture slurry. By including the step of evaluating the degree of dispersion of the positive electrode active material contained in the positive electrode mixture slurry using the disclosed method for evaluating a positive electrode mixture slurry, a coating film with good properties can be obtained when the produced positive electrode mixture slurry is used to form a coating film.

[0050] <Preliminary positive electrode composite slurry providing step> The disclosed method for producing a cathode mixture slurry includes (a) providing a preliminary cathode mixture slurry including an active cathode material and a dispersing medium.

[0051] (Cathode active material) As the positive electrode active material, a material exhibiting a noble potential relative to the negative electrode active material can be used. As such a positive electrode active material, a known active material may be used. For example, in the case of constructing a lithium ion battery, lithium cobalt oxide, lithium nickel oxide, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 Various lithium-containing composite oxides such as O2, lithium manganate, and spinel-based lithium compounds can be used. Lithium iron phosphate (LFP) can also be used as an olivine-type positive electrode active material.

[0052] The average particle size of the positive electrode active material may be 10 nm or more and 50 μm or less. The average particle size of the positive electrode active material may be 100 nm or more, or 500 nm or more, and may be 30 μm or less, or 10 μm or less.

[0053] (dispersion medium) For the dispersion medium, reference can be made to the above description regarding the method for producing the negative electrode mixture slurry of the present disclosure.

[0054] <Preliminary Positive Electrode Composite Slurry Stirring Step> The disclosed method for producing a cathode mixture slurry includes (b) stirring the preliminary cathode mixture slurry.

[0055] <Evaluation process> The disclosed method for producing a positive electrode mixture slurry includes (c) evaluating the degree of dispersion of the positive electrode active material contained in the positive electrode mixture slurry by the disclosed method for evaluating a positive electrode mixture slurry.

[0056] For the method of evaluating a positive electrode mixture slurry according to the present disclosure, reference can be made to the above description of the method of evaluating a positive electrode mixture slurry according to the present disclosure.

[0057] In the method of the present disclosure for producing a positive electrode mixture slurry, in step (c), a conversion value of the relaxation time of the positive electrode mixture slurry measured by the solid echo method, calculated based on the relaxation time of the dispersion medium, is 4.5 × 10 -5Over 5.4 x 10 -5 Steps (b) and (c) may be repeated until:

[0058] <Positive electrode mixture slurry> When the positive electrode composite slurry of the present disclosure is measured by a solid echo method using a time-domain nuclear magnetic resonance spectrometer, the converted value of the relaxation time calculated based on the relaxation time of the dispersion medium is 4.5 × 10 -5 Over 5.4 x 10 -5 The following is the result.

[0059] The above conversion value is 4.5 x 10 -5 That's it, 4.6 x 10 -5 or more, or 4.7 x 10 -5 may be greater than or equal to 5.4 x 10 -5 Below, 5.3 x 10 -5 or less, or 5.2 x 10 -5 If this converted value is within the above range, a coating film with good properties can be obtained.

[0060] Other ingredients The preliminary negative electrode composite slurry and the preliminary positive electrode composite slurry optionally contain a solid electrolyte. In this case, the average particle size of the solid electrolyte may be smaller than the average particle size of the negative electrode active material and the positive electrode active material. This configuration allows accurate evaluation of the dispersion degree of the negative electrode active material contained in the negative electrode composite slurry and the positive electrode active material contained in the positive electrode composite slurry. For details of the solid electrolyte, please refer to the above description of the manufacturing method of the solid electrolyte composite slurry of the present disclosure.

[0061] The preliminary negative electrode mixture slurry, the preliminary solid electrolyte mixture slurry, and the preliminary positive electrode mixture slurry may optionally contain a conductive additive and a binder.

[0062] (Conductive additive) The conductive additive is not particularly limited. The conductive additive may be, for example, vapor grown carbon fiber (VGCF), acetylene black (AB), ketjen black (KB), carbon nanotube (CNT), carbon nanofiber (CNF), etc., but is not limited thereto. The conductive additive may be, for example, particulate or fibrous, and its size is not particularly limited. The conductive additive is not particularly limited, and one type may be used alone, or two or more types may be used in combination.

[0063] (binder) The binder is not particularly limited as long as it is a binder that is commonly used as a binder for an electrode active material layer, and may be, for example, but is not limited to, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HEP), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethyl cellulose (CMC), hydroxypropyl cellulose, regenerated cellulose, polyethylene, polypropylene, starch, butadiene rubber (BR), styrene butadiene rubber (SBR), fluororubber, or a combination thereof.

[0064] <Battery manufacturing method> In one embodiment, the method of the present disclosure for producing a battery includes the following steps: providing a negative electrode composite slurry by the method of the present disclosure for producing a negative electrode composite slurry, and applying the negative electrode composite slurry to a substrate and then drying and removing the dispersion medium to form a negative electrode active material layer. By using such a method, a battery including a coating film with good properties, i.e., a negative electrode active material layer, can be produced.

[0065] <Negative electrode composite slurry providing step> The method of the present disclosure for producing a battery includes providing an anode mixture slurry by the method of the present disclosure for producing an anode mixture slurry. For the method of the present disclosure for producing an anode mixture slurry, reference may be made to the above description of the method of the present disclosure for producing an anode mixture slurry.

[0066] <Negative electrode active material layer formation process> The disclosed method for manufacturing a battery includes applying the negative electrode mixture slurry to a substrate and then drying to remove the dispersing medium to form a negative electrode active material layer.

[0067] (base material) The substrate is not particularly limited, but may be, for example, a negative electrode current collector.

[0068] (dispersion medium) For the dispersion medium, reference can be made to the above description regarding the method for producing the negative electrode mixture slurry of the present disclosure.

[0069] The method for applying the negative electrode composite slurry to the substrate is not particularly limited, but examples thereof include a blade coating method, which can also be applied to a battery manufacturing method according to another embodiment described below.

[0070] The method for drying and removing the dispersion medium from the negative electrode composite slurry is not particularly limited, but may include, for example, a method in which the coating film obtained by coating the negative electrode composite slurry is dried on a hot plate. The drying temperature, drying time, etc. can be appropriately designed depending on the boiling point, amount, etc. of the dispersion medium used. This method can also be applied to a battery manufacturing method according to another embodiment described below.

[0071] In another embodiment, a method of manufacturing a battery according to the present disclosure includes the steps of: providing a solid electrolyte mixture slurry by the method of manufacturing a solid electrolyte mixture slurry according to the present disclosure; and applying the solid electrolyte mixture slurry to a substrate and drying and removing the dispersion medium to form a solid electrolyte layer. By using such a method, a battery including a coating film, i.e., a solid electrolyte layer, with good properties can be manufactured.

[0072] <Solid electrolyte composite slurry providing step> The disclosed method for manufacturing a battery includes providing a solid electrolyte mixture slurry by the disclosed method for manufacturing a solid electrolyte mixture slurry, and reference can be made to the above description of the disclosed method for manufacturing a solid electrolyte mixture slurry.

[0073] <Solid electrolyte layer formation process> The disclosed method for manufacturing a battery includes applying a solid electrolyte mixture slurry to a substrate and drying to remove the carrier medium to form a solid electrolyte layer.

[0074] (base material) The substrate is not particularly limited, but may be, for example, a metal foil such as aluminum foil that can be peeled off after coating and drying.

[0075] (dispersion medium) For the dispersion medium, reference can be made to the above description regarding the method for producing the negative electrode mixture slurry of the present disclosure.

[0076] In another embodiment, a method for producing a battery according to the present disclosure includes the steps of: providing a cathode composite slurry by the method for producing a cathode composite slurry according to the present disclosure; applying the cathode composite slurry to a substrate; and drying and removing the dispersion medium to form a cathode active material layer. By using such a method, a battery including a coating film, i.e., a cathode active material layer, with good properties can be produced.

[0077] <Positive electrode composite slurry providing process> The method of the present disclosure for producing a battery includes providing a cathode mixture slurry by the method of the present disclosure for producing a cathode mixture slurry. For the method of the present disclosure for producing a cathode mixture slurry, reference may be made to the above description of the method of the present disclosure for producing a cathode mixture slurry.

[0078] <Cathode active material layer formation process> The disclosed method for manufacturing a battery includes applying a positive electrode mixture slurry to a substrate and then drying to remove the dispersing medium to form a positive electrode active material layer.

[0079] (base material) The substrate is not particularly limited, but may be, for example, a positive electrode current collector.

[0080] (dispersion medium) For the dispersion medium, reference can be made to the above description regarding the method for producing the negative electrode mixture slurry of the present disclosure.

[0081] "battery" A battery obtained by the disclosed method for producing a battery has at least one layer selected from the group consisting of an anode active material layer, a solid electrolyte layer, and a cathode active material layer. The battery obtained by the disclosed method for producing a battery may have an anode current collector, an anode active material layer, a solid electrolyte layer, a cathode active material layer, and a cathode current collector in this order.

[0082] The battery obtained by the method including the steps of providing a negative electrode composite slurry and forming a negative electrode active material layer, and the battery obtained by the method including the steps of providing a positive electrode composite slurry and forming a positive electrode active material layer, may be a liquid-based battery containing an electrolytic solution as the electrolyte layer, or may be a solid-state battery having a solid electrolyte layer as the electrolyte layer. The battery obtained by the method including the steps of providing a solid electrolyte composite slurry and forming a solid electrolyte layer may be a solid-state battery. Note that, in the context of the present disclosure, "solid-state battery" refers to a battery that uses at least a solid electrolyte as the electrolyte; therefore, a solid-state battery may use a combination of a solid electrolyte and a liquid electrolyte as the electrolyte. The solid-state battery of the present disclosure may also be an all-solid-state battery, i.e., a battery that uses only a solid electrolyte as the electrolyte.

[0083] The battery obtained by the disclosed method for manufacturing a battery may be a primary battery or a secondary battery, such as a lithium ion battery or a sodium ion battery.

[0084] <Negative electrode current collector> The material used for the negative electrode current collector is not particularly limited, and any material that can be used as a negative electrode current collector for a battery can be appropriately adopted. For example, stainless steel (SUS), aluminum, copper, nickel, iron, titanium, or carbon, a resin current collector, etc. may be used, but is not limited to these.

[0085] The shape of the negative electrode current collector is not particularly limited, and examples thereof include foil, plate, mesh, etc. Among these, foil is preferred.

[0086] <Negative electrode active material layer> The negative electrode active material layer may be a layer formed by drying and removing the dispersion medium in the negative electrode composite slurry of the present disclosure applied to the substrate. When the electrolyte layer is a layer formed by drying and removing the dispersion medium in the solid electrolyte composite slurry of the present disclosure applied to the substrate and / or the positive electrode active material layer is a layer formed by drying and removing the dispersion medium in the positive electrode composite slurry of the present disclosure applied to the substrate, the negative electrode active material layer may be one that is commonly used as a negative electrode active material layer for a battery.

[0087] <Electrolyte layer> When the battery is a solid-state battery, the electrolyte layer may be a layer formed by drying and removing the dispersion medium from the solid electrolyte composite slurry of the present disclosure applied to the substrate. When the battery is a solid-state battery and the negative electrode active material layer is a layer formed by drying and removing the dispersion medium from the negative electrode composite slurry of the present disclosure applied to the substrate and / or the positive electrode active material layer is a layer formed by drying and removing the dispersion medium from the positive electrode composite slurry of the present disclosure applied to the substrate, the electrolyte layer may be a layer commonly used as an electrolyte layer for solid-state batteries. When the battery is a liquid-based battery, the electrolyte layer may be a layer formed by impregnating a separator with an electrolyte solution. The separator and electrolyte solution are not particularly limited and may be those commonly used as a separator and electrolyte solution for batteries.

[0088] <Cathode active material layer> The positive electrode active material layer may be a layer formed by drying and removing the dispersion medium in the positive electrode composite slurry of the present disclosure applied to the substrate. When the negative electrode active material layer is a layer formed by drying and removing the dispersion medium in the negative electrode composite slurry of the present disclosure applied to the substrate and / or the electrolyte layer is a layer formed by drying and removing the dispersion medium in the solid electrolyte composite slurry of the present disclosure applied to the substrate, the positive electrode active material layer may be one that is commonly used as a positive electrode active material layer for a battery.

[0089] <Positive electrode current collector> The material and shape of the positive electrode current collector are not particularly limited, and the above description of the negative electrode active material layer of the present disclosure can be referenced. For example, the material of the positive electrode current collector may be aluminum. The shape may be a foil. [Example]

[0090] Examples 1 to 3, Comparative Examples 1 to 3, and Reference Example 1 <Preparation of Negative Electrode Composite Slurry> (Preliminary negative electrode composite slurry providing step and stirring step) A lithium titanate (LTO)-based negative electrode active material, a sulfide-based solid electrolyte, vapor-grown carbon fiber (VGCF) as a conductive additive, a PVdF-based binder, and butyl butyrate as a dispersion medium were mixed in an ultrasonic disperser and further mixed with a stirring blade to produce negative electrode composite slurries of Examples 1 to 3 and Comparative Examples 1 and 2. The slurry before ultrasonic mixing was used as the negative electrode composite slurry of Comparative Example 3.

[0091] (Negative electrode active material layer formation process) The obtained negative electrode mixture slurry was applied onto an aluminum (Al) foil by a blade method, and this was dried at 100° C. on a hot plate for 30 minutes to obtain a negative electrode active material layer (coating film).

[0092] A slurry of Reference Example 1 was obtained in the same manner as in Examples 1 to 3 and Comparative Examples 1 and 2, except that the negative electrode active material and the conductive additive were not used.

[0093] <evaluation> (Dispersion degree) The relaxation time (T2) of each negative electrode composite slurry was measured using a time-domain nuclear magnetic resonance (TDNMR) instrument (Bruker, Minispec mq20) to evaluate the dispersion of the components in the slurry. The relaxation time was measured using the CPMG method. The equivalent relaxation time was calculated using the data analysis software TDNMR-A provided with the TDNMR instrument. That is, the ratio of the relaxation time of the negative electrode composite slurry to the relaxation time of the butyl acetate dispersion medium was calculated to obtain the equivalent value.

[0094] As a reference value, the point at which particles begin to appear was observed using the particle gauge method, and the dispersion degree of the components in the slurry was evaluated from the reading. The measurement was carried out in accordance with JIS K 5600-2-5:1999.

[0095] (Coating film properties) The negative electrode active material layer as a coating film was visually inspected for appearance, and the presence or absence of aggregates of 0.5 mm or more was confirmed using a gauge. In this case, the case where no aggregates were observed was evaluated as ◯, and the case where the aggregates were observed was evaluated as ×.

[0096] <result> Table 1 shows the relaxation time, coating film properties, and the dispersion degree measured by the particle gauge method as a reference value.

[0097] [Table 1]

[0098] As shown in Table 1, the dispersion degree measured by the particle gauge method in the negative electrode composite slurry of the Example was equal to or greater than the values of Comparative Examples 1 and 2, but the relaxation time measured by the TDNMR device was within a predetermined range, and therefore the properties of the obtained coating film were good. Furthermore, for the unstirred Comparative Example 3, both the dispersion degree measured by the particle gauge method and the relaxation time were greater than the values of the Example and Comparative Examples 1 and 2.

[0099] The fact that the relaxation time of the slurry of the Reference Example, which does not contain any negative electrode active material, is significantly longer than the relaxation times of the negative electrode composite slurries of the Examples and Comparative Examples is thought to indicate that the relaxation times of the Examples and Comparative Examples are due to the degree of dispersion of the negative electrode active material.

[0100] Examples 4 to 6, Comparative Examples 4 to 6, and Reference Example 2 <Preparation of Solid Electrolyte Composite Slurry> (Preliminary solid electrolyte composite slurry providing step and stirring step) A sulfide-based solid electrolyte, a PVdF-based binder, and butyl butyrate as a dispersion medium were mixed using an ultrasonic disperser and further mixed using a stirring blade to prepare solid electrolyte composite slurries of Examples 4 to 6 and Comparative Examples 4 and 5. The slurry before ultrasonic mixing was used as the solid electrolyte composite slurry of Comparative Example 6.

[0101] (Solid electrolyte layer formation process) A solid electrolyte layer (coating film) was formed in the same manner as in the above-described negative electrode active material layer forming step, except that a solid electrolyte mixture slurry was used instead of the negative electrode mixture slurry.

[0102] A PVdF binder and butyl butyrate as a dispersion medium were mixed with a stirrer to prepare a slurry of Reference Example 2.

[0103] <evaluation> (Dispersion degree) The relaxation time (T2) of the solid electrolyte composite slurry was measured in the same manner as in the case of using the negative electrode composite slurry, except that the solid electrolyte composite slurry of each example was used instead of the negative electrode composite slurry, and the degree of dispersion of the solid electrolyte in the slurry was evaluated.

[0104] (Coating film properties) The properties of the coating film were evaluated in the same manner as in the case where a negative electrode active material layer was used, except that a solid electrolyte layer was used as the coating film instead of the negative electrode active material layer.

[0105] <result> Table 2 shows the relaxation time, coating film properties, and the dispersion degree measured by the particle gauge method as a reference value.

[0106] [Table 2]

[0107] As shown in Table 2, the dispersion degree measured by the particle gauge method in the solid electrolyte mixture slurry of the Example was equal to or greater than the values in Comparative Examples 4 and 5, but the relaxation time measured by the TDNMR apparatus was within a predetermined range, and therefore the properties of the obtained coating film were good. Furthermore, for the unstirred Comparative Example 6, both the dispersion degree measured by the particle gauge method and the relaxation time were greater than the values in the Example and Comparative Examples 4 and 5.

[0108] The fact that the relaxation time of the slurry of the Reference Example, which does not contain a solid electrolyte, is significantly longer than the relaxation times of the solid electrolyte composite slurries of the Examples and Comparative Examples is considered to indicate that the relaxation times of the Examples and Comparative Examples are due to the degree of dispersion of the solid electrolyte.

[0109] Examples 7 to 9 and Comparative Examples 7 to 9 <Preparation of Positive Electrode Composite Slurry> (Preliminary positive electrode composite slurry providing step and stirring step) An NCA-based positive electrode active material, a sulfide-based solid electrolyte, vapor-grown carbon fiber (VGCF) as a conductive additive, a PVdF-based binder, and butyl butyrate as a dispersion medium were mixed in an ultrasonic disperser and further mixed with a stirring blade to produce positive electrode composite slurries of Examples 7 to 9 and Comparative Examples 7 and 8. The slurry before ultrasonic mixing was used as the positive electrode composite slurry of Comparative Example 9.

[0110] (Cathode active material layer formation process) A positive electrode active material layer (coating film) was formed in the same manner as in the above negative electrode active material layer forming step, except that a positive electrode composite material slurry was used instead of the negative electrode composite material slurry.

[0111] <evaluation> (Dispersion degree) The relaxation time (T2) of the positive electrode composite slurry was measured in the same manner as in the case of using the negative electrode composite slurry, except that the positive electrode composite slurry of each example was used instead of the negative electrode composite slurry, to evaluate the degree of dispersion of the positive electrode active material in the slurry.

[0112] (Coating film properties) The properties of the coating film were evaluated in the same manner as in the case where a negative electrode active material layer was used, except that a positive electrode active material layer was used as the coating film instead of a negative electrode active material layer.

[0113] <result> Table 3 shows the relaxation time, coating film properties, and the dispersion degree measured by the particle gauge method as a reference value.

[0114] [Table 3]

[0115] As shown in Table 3, the dispersion degree measured by the particle gauge method in the positive electrode composite slurry of the Example was equal to or greater than the values of Comparative Examples 7 and 8, but the relaxation time measured by the TDNMR apparatus was within a predetermined range, and therefore the properties of the obtained coating film were good. Furthermore, for the unstirred Comparative Example 9, both the dispersion degree measured by the particle gauge method and the relaxation time were greater than the values of the Example and Comparative Examples 7 and 8.

Claims

1. A method for evaluating a battery slurry, comprising: measuring a relaxation time of the battery slurry using a time-domain nuclear magnetic resonance spectrometer, thereby evaluating a degree of dispersion of a specific component contained in the battery slurry.

2. The method according to claim 1 , wherein the battery slurry is a negative electrode mixture slurry, and the specific component is a negative electrode active material.

3. The method according to claim 2 , wherein the relaxation time is measured by a CPMG method.

4. A method for producing a negative electrode mixture slurry, comprising the following steps: (a) providing a preliminary negative electrode mixture slurry containing a negative electrode active material and a dispersion medium; (b) stirring the preliminary negative electrode composite slurry; and (c) Evaluating the degree of dispersion of the negative electrode active material contained in the negative electrode mixture slurry by the method according to claim 2.

5. 5. The method of claim 4, wherein in the step (c), the steps (b) and (c) are repeated until a converted value of the relaxation time of the negative electrode composite slurry measured by a CPMG method, calculated based on the relaxation time of the dispersion medium, is 0.015 or more and 0.025 or less.

6. The method according to claim 4 , wherein the average particle size of the negative electrode active material is 10 nm or more and 50 μm or less.

7. A method for manufacturing a battery, comprising the steps of: Providing a negative electrode mixture slurry by the method according to any one of claims 4 to 6; and The negative electrode mixture slurry is applied to a substrate, and the dispersion medium is then dried and removed to form a negative electrode active material layer.

8. A negative electrode composite slurry, wherein, when measured by a CPMG method using a time-domain nuclear magnetic resonance spectrometer, a converted value of a relaxation time calculated based on a relaxation time of a dispersion medium is 0.015 or more and 0.025 or less.

9. 10. The method of claim 1, wherein the battery slurry is a solid electrolyte mixture slurry and the specific component is a solid electrolyte.

10. The method according to claim 9, wherein the relaxation time is measured by a CPMG method.

11. A method for producing a solid electrolyte mixture slurry, comprising the steps of: (a) providing a preliminary solid electrolyte mixture slurry including a solid electrolyte and a dispersion medium; (b) stirring the preliminary solid electrolyte mixture slurry; and (c) Evaluating the degree of dispersion of the solid electrolyte contained in the solid electrolyte mixture slurry by the method according to claim 9.

12. 12. The method according to claim 11, wherein in the step (c), the steps (b) and (c) are repeated until a converted value of the relaxation time of the solid electrolyte mixture slurry measured by a CPMG method, calculated based on the relaxation time of the dispersion medium, is 0.45 or more and 0.50 or less.

13. The method according to claim 11, wherein the solid electrolyte has an average particle size of 1 nm or more and 10 μm or less.

14. A method for manufacturing a battery, comprising the steps of: Providing a solid electrolyte mixture slurry by the method according to any one of claims 11 to 13; and The solid electrolyte mixture slurry is applied to a substrate, and the dispersion medium is then dried and removed to form a solid electrolyte layer.

15. A solid electrolyte composite slurry, wherein a converted value of a relaxation time calculated based on a relaxation time of a dispersion medium is 0.45 or more and 0.50 or less when measured by a CPMG method using a time-domain nuclear magnetic resonance spectrometer.

16. The method according to claim 1 , wherein the battery slurry is a positive electrode mixture slurry and the specific component is a positive electrode active material.

17. The method of claim 16, wherein the relaxation time is measured by a solid echo method.

18. A method for producing a positive electrode mixture slurry, comprising the following steps: (a) providing a preliminary positive electrode mixture slurry containing a positive electrode active material and a dispersion medium; (b) stirring the preliminary cathode composite slurry; and (c) Evaluating the degree of dispersion of the positive electrode active material contained in the positive electrode mixture slurry by the method according to claim 16.

19. In the step (c), the converted value of the relaxation time of the positive electrode composite slurry measured by a solid echo method, calculated based on the relaxation time of the dispersion medium, is 4.5 × 10 －５ 5.4 x 10 －５ 20. The method of claim 18, wherein steps (b) and (c) are repeated until:

20. The method according to claim 18, wherein the average particle size of the positive electrode active material is 10 nm or more and 50 μm or less.

21. A method for manufacturing a battery, comprising the steps of: Providing a positive electrode mixture slurry by the method according to any one of claims 18 to 20; and The positive electrode mixture slurry is applied to a substrate, and the dispersion medium is then dried and removed to form a positive electrode active material layer.

22. When measured by the solid echo method using a time-domain nuclear magnetic resonance spectrometer, the converted value of the relaxation time calculated based on the relaxation time of the dispersion medium was 4.5 × 10 －５ 5.4 x 10 －５ The positive electrode mixture slurry is as follows:

Images