Method for producing electrode mixture slurry and method for producing electrode active material layer

Abstract

The manufacturing method of the electrode mixture slurry of the present disclosure includes the following steps: mixing solid electrolyte particles, a dispersing agent, and a solvent to prepare a solid electrolyte slurry; and mixing porous electrode active material particles and the solid electrolyte slurry. In the method of the present disclosure, the following relationships (1) and (2) are satisfied: specific surface area of the porous electrode active material particles > specific surface area of the solid electrolyte particles... (1); average particle size of the porous electrode active material particles > average particle size of the solid electrolyte particles... (2). The method of the present disclosure for manufacturing an electrode active material layer includes the following steps: manufacturing an electrode mixture slurry by the method of the present disclosure; and coating the electrode mixture slurry on a substrate, and then removing the solvent by drying.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing an electrode mixture slurry and a method for manufacturing an electrode active material layer. Background Technology

[0002] As disclosed in Japanese Patent Application Publication No. 2017-054720, a negative electrode (negative electrode active material layer) for an all-solid-state battery having a solid electrolyte and a negative electrode active material is known. Summary of the Invention

[0003] There is room for improvement in the ionic conductivity of the electrode active material layer, which contains a solid electrolyte and electrode active material.

[0004] The purpose of this disclosure is to provide a method for manufacturing an electrode paste that can improve the ionic conductivity of an electrode active material layer, and a method for manufacturing an electrode active material layer including the step of manufacturing the electrode paste using this method.

[0005] The inventors of this application have discovered that the above-mentioned problems can be solved by the following technical means.

[0006] <Technical Solution 1>

[0007] A method for manufacturing an electrode paste includes the following steps:

[0008] Solid electrolyte particles, dispersants, and solvents are mixed to prepare a solid electrolyte slurry; and

[0009] The porous electrode active material particles are mixed with the solid electrolyte slurry.

[0010] Furthermore, the following relations (1) and (2) are satisfied.

[0011] The specific surface area of ​​the porous electrode active material particles is greater than the specific surface area of ​​the solid electrolyte particles... (1).

[0012] The average particle size of the porous electrode active material particles is greater than the average particle size of the solid electrolyte particles... (2).

[0013] <Technical Solution 2>

[0014] According to the manufacturing method of electrode mixture slurry described in technical solution 1,

[0015] The porous electrode active material particles are composite particles of electrode active materials, and

[0016] The electrode active material composite particles are secondary particles formed from multiple primary electrode active material particles and having multiple fine pores between the primary electrode active material particles.

[0017] <Technical Solution 3>

[0018] According to the manufacturing method of electrode mixture slurry described in technical solution 1 or 2,

[0019] The ratio of the specific surface area of ​​the porous electrode active material particles to the specific surface area of ​​the solid electrolyte particles is S. AM / S SE 1 < S AM / S SE ≤10, and / or

[0020] The ratio of the average particle size of the porous electrode active material particles to the average particle size of the solid electrolyte particles is d. AM / d SE For 50≤d AM / d SE ≤200.

[0021] <Technical Solution 4>

[0022] The method for manufacturing electrode paste according to any one of technical solutions 1 to 3

[0023] The specific surface area of ​​the porous electrode active material particles is 50 m². 2 / g~300m 2 / g, and the specific surface area of ​​the solid electrolyte particles is 10m². 2 / g~100m 2 / g, and / or

[0024] The average particle size of the porous electrode active material particles is 1 μm to 20 μm, and the average particle size of the solid electrolyte particles is 0.01 μm to 1 μm.

[0025] <Technical Solution 5>

[0026] A method for manufacturing an electrode active material layer includes the following steps:

[0027] The electrode mixture slurry is manufactured using the manufacturing method of any one of technical solutions 1 to 4; and

[0028] The electrode mixture slurry is coated onto a substrate, and then the solvent is dried and removed.

[0029] According to the method of this disclosure for manufacturing electrode paste, it is possible to provide an electrode paste that can improve the ionic conductivity of the electrode active material layer.

[0030] According to the method of this disclosure for manufacturing an electrode active material layer, it is possible to provide an electrode active material layer with improved ionic conductivity.

[0031] The features, advantages, technical and industrial significance of exemplary embodiments of the present disclosure will now be described in conjunction with the accompanying drawings. In these drawings, the same reference numerals denote the same elements. Attached Figure Description

[0032] Figure 1A This is an image of the electrode mixture slurry of Comparative Example 1 under tension on a particle size analyzer.

[0033] Figure 1B This is an image of the electrode mixture slurry from Example 1 stretched on a particle size analyzer.

[0034] Figure 1C This is an image of the electrode mixture slurry of Comparative Example 2 under tension on a particle size analyzer.

[0035] Figure 2 This is a graph showing the ionic conductivity of the electrode active material layer in Example 1 and Comparative Examples 1 and 2. Detailed Implementation

[0036] The embodiments of this disclosure will now be described in detail. This disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the disclosure.

[0037] [Preparation method of electrode mixture slurry]

[0038] The method for manufacturing the electrode mixture slurry disclosed herein includes the following steps:

[0039] Solid electrolyte particles, dispersants, and solvents are mixed to prepare a solid electrolyte slurry; and

[0040] The porous electrode active material particles are mixed with the solid electrolyte slurry.

[0041] Furthermore, in the method disclosed herein, the following relations (1) and (2) are satisfied:

[0042] The specific surface area of ​​the active material particles in porous electrodes is greater than that of the particles in solid electrolytes... (1);

[0043] The average particle size of the active material particles in porous electrodes is greater than the average particle size of the solid electrolyte particles... (2).

[0044] Previously, it was believed that particles with larger specific surface areas were more difficult to disperse in solvents than particles with smaller specific surface areas. Based on this assumption, it was considered preferable to first disperse particles with larger specific surface areas together with a dispersant in a solvent to prepare a slurry, and then disperse particles with smaller specific surface areas in the resulting slurry.

[0045] In contrast, the inventors of this application conceived of preparing an intermediate slurry (solid electrolyte slurry) by first dispersing such particles, such as the solid electrolyte particles of this disclosure, in a solvent with a dispersant, when their average particle size and specific surface area are both smaller than previously thought. The inventors of this application discovered that by dispersing particles with larger average particle size and specific surface area, such as the porous electrode active material particles of this disclosure, in the obtained intermediate slurry, the dispersibility of the two types of particles in the slurry can be improved.

[0046] As a reason, without intending to be bound by any theory, the following speculation is made. That is, it is believed that particles with a relatively large average particle size are difficult to aggregate even with a large specific surface area, thus possessing a certain degree of dispersibility. Therefore, the inventors believe that by first mixing particles with smaller average particle size and specific surface area, such as the solid electrolyte particles of this disclosure, with a dispersant and a solvent, the dispersant can be distributed throughout the surface of the particles. Thus, the inventors believe that an intermediate slurry (solid electrolyte slurry) with improved particle dispersibility can be prepared. The inventors believe that in such an intermediate slurry, particles with larger average particle size and specific surface area, such as the porous electrode active material particles of this disclosure, can be dispersed. As a result, the inventors believe that a final slurry (electrode mixture slurry) with improved dispersibility of both types of particles can be obtained. Furthermore, it is believed that in the electrode active material layer manufactured from such an electrode mixture slurry, there is less aggregation of individual particles, thus resulting in improved ionic conductivity.

[0047] Regarding this disclosure, "electrode mixture" refers to a composition that can directly or further contain other components to form an electrode active material layer. Additionally, regarding this disclosure, "electrode mixture slurry" refers to a slurry that, in addition to the "electrode mixture," also contains a dispersion medium, thereby enabling coating and drying to form an electrode active material layer.

[0048] Regarding this disclosure, "electrode mixture" can be either "positive electrode mixture" or "negative electrode mixture," especially "negative electrode mixture."

[0049] The method for manufacturing electrode paste of the present disclosure will now be described in more detail.

[0050] [Preparation of Solid Electrolyte Slurry]

[0051] The method disclosed herein includes mixing solid electrolyte particles, a dispersant, and a solvent to prepare a solid electrolyte slurry.

[0052] There are no particular limitations on the method of mixing solid electrolyte particles, dispersants and solvents; ultrasonic-based dispersion mixing can be exemplified.

[0053] In this process, other components besides those mentioned above may be further mixed, or they may not be mixed. Conductive additives can be cited as examples of such components.

[0054] [Mixing of porous electrode active material particles with solid electrolyte slurry]

[0055] The method disclosed herein includes mixing porous electrode active material particles with a solid electrolyte slurry.

[0056] There are no particular limitations on the method of mixing porous electrode active material particles with solid electrolyte slurry; ultrasonic dispersion mixing can be exemplified.

[0057] In this process, the other components may be further mixed, or they may not be mixed. An example of such a component is an adhesive.

[0058] In the method disclosed herein, the following relations (1) and (2) are satisfied:

[0059] The specific surface area of ​​the active material particles in porous electrodes is greater than that of the particles in solid electrolytes…(1);

[0060] The average particle size of the active material particles in porous electrodes is greater than the average particle size of the solid electrolyte particles…(2).

[0061] The inventors believe that, when equations (1) and (2) are satisfied, the dispersion of both solid electrolyte particles and porous electrode active material particles in the electrode slurry is improved by manufacturing the electrode slurry using the above steps. Therefore, the inventors believe that it is possible to provide an electrode slurry that can improve the ionic conductivity of the electrode active material layer.

[0062] In the method disclosed herein:

[0063] The ratio of the specific surface area of ​​porous electrode active material particles to the specific surface area of ​​solid electrolyte particles (S) AM / S SE It can be 1 < S AM / S SE ≤10、3≤S AM / S SE ≤8, or 4≤S AM / S SE ≤6, and / or

[0064] The ratio of the average particle size of the porous electrode active material to the average particle size of the solid electrolyte is d. AM / d SE It can be 50≤d AM / d SE ≤200、70≤d AM / d SE≤150, or 80≤d AM / d SE ≤120.

[0065] S AM / S SE It can be greater than 1, greater than 2, greater than 3, greater than 4, or greater than 5. Alternatively, it can be less than 10, less than 9, less than 8, less than 7, less than 6, or less than 5.

[0066] d AM / d SE It can be 50 or above, 60 or above, 70 or above, 80 or above, 90 or above, or 100 or above. Alternatively, it can be below 200, below 170, below 150, below 130, below 120, below 110, or below 100.

[0067] By making S AM / S SE and / or d AM / d SE Within the aforementioned scope, electrode pastes are available that can effectively improve the ionic conductivity of the electrode active material layer.

[0068] In the method disclosed herein:

[0069] Specific surface area S of porous electrode active material particles AM It can be 50m 2 / g~300m 2 / g, 100m 2 / g~200m 2 / g, or 130m 2 / g~170m 2 / g, and the specific surface area S of the solid electrolyte particles SE It can be 10m 2 / g~100m 2 / g, 15m 2 / g~70m 2 / g, or 20m 2 / g~50m 2 / g, and / or

[0070] The average particle size d of porous electrode active material particles AM The particle size can be 1μm~20μm, 3μm~17μm, or 5μm~15μm, and the average particle size d of the solid electrolyte particles is... SE It can be 0.01μm~1μm, 0.03μm~0.7μm, or 0.05μm~0.5μm.

[0071] S AM It can be 50m 2 / g or more, 80m 2 / g or more, 100m 2 / g or more, 120m 2 / g or more, 130m 2 / g or more, 140m 2 / g or more or 150m 2 / g or more. Additionally, S AM It can be 300m 2 / g or less, 250m 2 / g or less, 200m 2 / g or less, 180m 2 / g or less, 170m 2 / g or less, 160m 2 / g or less or 150m 2 / g or less.

[0072] S SE It can be 10m 2 / g or more, 15m 2 / g or more, 20m 2 / g or more, 25m 2 / g or more or 30m 2 / g or more. Additionally, S SE It can be 100m 2 / g or less, 70m 2 / g or less, 50m 2 / g or less, 40m 2 / g or less or 30m 2 / g or less.

[0073] d AM It can be 1μm or larger, 3μm or larger, 5μm or larger, 7μm or larger, 8μm or larger, 9μm or larger, or 10μm or larger. Additionally, d AM It can be below 20μm, below 17μm, below 15μm, below 13μm, below 12μm, below 11μm, or below 10μm.

[0074] d SE It can be 0.01μm or larger, 0.03μm or larger, 0.05μm or larger, 0.07μm or larger, 0.08μm or larger, 0.09μm or larger, or 0.1μm or larger. Additionally, d SE It can be below 1μm, below 0.7μm, below 0.5μm, below 0.3μm, below 0.2μm, or below 0.1μm.

[0075] By making S AM and S SE and / or d AM and d SEWithin the aforementioned scope, electrode pastes are available that can effectively improve the ionic conductivity of the electrode active material layer.

[0076] The average particle size can be determined by observation using electron microscopy such as scanning electron microscopy (SEM), for example, by averaging the maximum Feretta diameters of multiple particles. A larger sample size is better, for example, 20 or more, 50 or more, or 100 or more.

[0077] Specific surface area can be determined using a specific surface area pore distribution measuring device, by nitrogen adsorption, or by the BET method.

[0078] The following describes the materials that can be used in the methods of this disclosure.

[0079] [Solid electrolyte particles]

[0080] As solid electrolyte particles, there are no special limitations as long as their relationship with porous electrode active material particles satisfies the above-mentioned relationships (1) and (2).

[0081] Examples of solid electrolyte particles include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and halide solid electrolytes, as well as organic polymer electrolytes such as polymer electrolytes. Sulfide solid electrolyte particles are particularly noteworthy.

[0082] For example, in the case of a lithium-ion secondary battery, solid electrolyte particles can have lithium-ion conductivity.

[0083] Examples of sulfide solid electrolyte particles with lithium-ion conductivity include, for example, Li and X (where X is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In). Furthermore, solid electrolyte particles containing S can be listed. Additionally, sulfide solid electrolyte particles may further contain at least one of O and a halogen element. Examples of halogen elements include F, Cl, Br, and I.

[0084] Examples of sulfide solid electrolyte particles include Li₂S-P₂S₅, Li₂S-P₂S₅-LiI, Li₂S-P₂S₅-GeS₂, Li₂S-P₂S₅-Li₂O, Li₂S-P₂S₅-Li₂O-LiI, and Li₂S-P₂S₅-LiI-LiBr. Other examples include Li₂S-SiS₂, Li₂S-SiS₂-LiI, Li₂S-SiS₂-LiBr, Li₂S-SiS₂-LiCl, Li₂S-SiS₂-B₂S₃-LiI, Li₂S-SiS₂-P₂S₅-LiI, Li₂S-B₂S₃, and Li₂S-P₂S₅-Z. m S n (m and n are positive numbers, and Z is any one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, and Li2S-SiS2-Li x MO y (x and y are positive numbers, and M is any one of P, Si, Ge, B, Al, Ga, and In) particles.

[0085] Examples of oxide solid electrolyte particles with lithium-ion conductivity include, for example, elements Li and Y (where Y is at least one of Nb, B, Al, Si, P, Ti, Zr, Mo, W, and S). Furthermore, solid electrolyte particles containing element O can be cited. A specific example is Li7La3Zr2O. 12 Li 7-x La3(Zr 2-x Nb x )O 12 (0≤x≤2), Li5La3Nb2O 12 Garnet-type solid electrolyte particles; perovskite-type solid electrolyte particles such as (Li,La)TiO3, (Li,La)NbO3, and (Li,Sr)(Ta,Zr)O3. Additionally, examples include NASICON-type solid electrolyte particles such as Li(Al,Ti)(PO4)3 and Li(Al,Ga)(PO4)3; Li-PO4-based solid electrolyte particles such as Li3PO4 and LIPON (a compound in which some of the O in Li3PO4 is replaced by N); and Li-BO4-based solid electrolyte particles such as Li3BO3 and compounds in which some of the O in Li3BO3 is replaced by C.

[0086] There is no particular limitation on the content of solid electrolyte particles in the solid components of solid electrolyte slurry and electrode mixture slurry; it can be appropriately set considering the desired ionic conductivity, etc.

[0087] [Dispersant]

[0088] As a dispersant, there are no particular limitations as long as it can function as a dispersant relative to porous electrode active material particles and solid electrolyte particles.

[0089] There is no particular limitation on the content of dispersant in the solid components of solid electrolyte slurry and electrode mixture slurry; it can be set appropriately by considering the desired dispersion performance.

[0090] [Porous electrode active material particles]

[0091] As for the active material particles of porous electrodes, there are no special restrictions as long as their relationship with the solid electrolyte particles satisfies the above-mentioned equations (1) and (2).

[0092] Regarding this disclosure, "porous electrode active material particles" refers to particles having multiple fine pores. "Electrode active material" can be either "positive electrode active material" or "negative electrode active material," especially "negative electrode active material."

[0093] Porous electrode active material particles can be primary particles of porous electrode active material with multiple fine pores inside the primary particles.

[0094] Alternatively, porous electrode active material particles can also be composite particles of electrode active materials. Here, the composite particles of electrode active materials are secondary particles formed by multiple primary particles of electrode active materials, and have multiple fine pores between the primary particles of electrode active materials. In this case, it is easy to increase the average particle size of the porous electrode active material particles, and therefore it is easy to satisfy the above relationship (2).

[0095] The primary particles of the electrode active material in the electrode active material composite particles can be porous primary particles of electrode active material. That is, the "porous electrode active material particles" can have multiple pores within the primary particles and multiple pores between the primary particles inside the secondary particles. In this case, it is easy to increase the specific surface area and the average particle size, so it is easy to satisfy the above relationships (1) and (2).

[0096] The electrode active material can be silicon. That is, the porous electrode active material particles can be primary particles of porous silicon electrode active material, or composite particles of silicon electrode active material formed by multiple primary silicon electrode active material particles. Silicon expands and contracts during the charging and discharging of the battery, thereby sometimes reducing the contact area between silicon electrode active material particles and solid electrolyte particles in the electrode active material layer. This is one of the reasons for the decrease in ionic conductivity. Therefore, when the electrode active material is silicon, the method disclosed herein is of great significance.

[0097] The composition of the primary particles of the silicon electrode active material is not particularly limited as long as they contain silicon. The proportion of silicon in the total elements contained in the primary particle can be, for example, 50 mol% or more, 70 mol% or more, 90 mol% or more, 95 mol% or more, or 99 mol% or more. The primary particle may contain elements other than silicon, or it may not contain any. Other elements, besides Li, include Sn, Fe, Co, Ni, Ti, Cr, B, P, etc. The primary particle may contain silicon oxides.

[0098] The primary particles of the active material in silicon electrodes can be either amorphous or crystalline. There are no particular limitations on the crystalline phase contained in silicon.

[0099] The primary particles of the porous silicon electrode active material can be the aforementioned primary particles of the silicon electrode active material that have been porousized. Conventional methods can be used to porousize the primary particles of the silicon electrode active material.

[0100] When the porous electrode active material particles are electrode active material composite particles, the electrode active material composite particles can further include a binder. The binder can bond multiple primary electrode active material particles together, thereby facilitating the preparation of electrode active material composite particles.

[0101] The binder that can be included in the electrode active material composite particles is not particularly limited. For example, it can be a butadiene rubber (BR) based binder, an insulated rubber (IIR) based binder, an acrylate butadiene rubber (ABR) based binder, a styrene butadiene rubber (SBR) based binder, a polyvinylidene fluoride (PVdF) based binder, a polytetrafluoroethylene (PTFE) based binder, a polyimide (PI) based binder, a carboxymethyl cellulose (CMC) based binder, a polyacrylate based binder, a polyacrylate based binder, or a combination thereof.

[0102] There is no particular limitation on the content of primary particles of electrode active material in the electrode active material composite particles. It can be appropriately set by considering the desired battery capacity, etc.

[0103] There is no particular limitation on the content of binder in the composite particles of electrode active material; it can be set appropriately by considering the desired adhesion, etc.

[0104] Electrode active material composite particles can be manufactured by a method including the following steps:

[0105] Provides a slurry containing primary particles of electrode active material and a dispersion medium; and

[0106] The dispersion medium is removed by spray drying.

[0107] Regarding the primary particles of the electrode active material, please refer to the above description.

[0108] As a dispersion medium, there are no particular limitations as long as it can disperse the primary particles of the electrode active material.

[0109] When the electrode active material composite particles also contain a binder, there are no particular limitations on the dispersion medium, as long as it can disperse the primary particles of the electrode active material and dissolve or disperse the binder.

[0110] Regarding adhesives, please refer to the above description.

[0111] By adjusting the concentration of solid components in the slurry and the slurry feed rate, spray pressure, and drying temperature during spray drying, the average particle size of the electrode active material composite particles can be controlled.

[0112] There is no particular limitation on the content of porous electrode active material particles in the solid components of the electrode mixture slurry; it can be appropriately set by considering the desired battery capacity, etc.

[0113] [Conductive additives]

[0114] Conductive additives can be, for example, carbon materials, metal particles, or combinations thereof. Carbon materials can be, for example, combinations of the following: non-fibrous carbon materials such as acetylene black (AB) and Ketjen black (KB); fibrous carbon materials such as vapor-grown carbon fibers (VGCF), carbon nanotubes (CNTs), and carbon nanofibers (CNF); or combinations thereof. Metal particles can be, for example, nickel, copper, iron, stainless steel, or combinations thereof.

[0115] There is no particular limitation on the content of conductive additives in the solid components of solid electrolyte slurries and electrode mixture slurries; it can be appropriately set considering the desired conductivity, etc.

[0116] [Adhesive]

[0117] The adhesives that may be included in the electrode slurry can be, for example, combinations of the following: rubber-based adhesives such as butadiene rubber, hydrogenated butadiene rubber, styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, acrylate butadiene rubber (ABR), and ethylene propylene rubber; fluorinated adhesives such as polyvinylidene fluoride (PVdF), polyvinylidene fluoride-polyhexafluoropropylene copolymer (PVdF-HFP), polytetrafluoroethylene, and fluororubber; polyolefin thermoplastic resins such as polyethylene, polypropylene, and polystyrene; imide resins such as polyimide and polyamide-imide; amide resins such as polyamide; acrylic resins such as polymethyl acrylate and polyethyl acrylate; methacrylic resins such as polymethyl methacrylate and polyethyl methacrylate; or combinations thereof.

[0118] There is no particular limitation on the content of binder in the solid components of the electrode mixture slurry; it can be set appropriately by considering the desired adhesion, etc.

[0119] [solvent]

[0120] As a solvent, there are no particular limitations as long as it can disperse the porous electrode active material particles and the solid electrolyte particles. When the electrode slurry also contains conductive additives and binders, the solvent can be one that can disperse the conductive additives and dissolve or disperse the binders. Tetrahydronaphthalene is an example of such a dispersion medium.

[0121] [Method for manufacturing the electrode active material layer]

[0122] The method of this disclosure for manufacturing an electrode active material layer includes the following steps:

[0123] Electrode mixture slurry is manufactured using the method disclosed herein; and

[0124] The electrode mixture slurry is applied to the substrate, and then the solvent is dried and removed.

[0125] This allows for the provision of an electrode active material layer with improved ionic conductivity.

[0126] Regarding this disclosure, the "electrode active material layer" can be either a "positive electrode active material layer" or a "negative electrode active material layer," especially a "negative electrode active material layer."

[0127] [Preparation of Electrode Mixture Slurry]

[0128] The method disclosed herein includes manufacturing an electrode mixture slurry using the method of this disclosure. The method of this disclosure for manufacturing the electrode mixture slurry can be referred to the above description.

[0129] [Removal of solvent by drying]

[0130] The method disclosed herein includes: coating an electrode mixture slurry onto a substrate, and then drying off the solvent.

[0131] There are no particular limitations on the method for applying electrode paste; conventional methods can be used.

[0132] There are no particular limitations on the substrate used for coating the electrode paste; for example, it can be a current collector layer or a release sheet. Regarding the current collector layer, please refer to the descriptions of the negative electrode stack and the positive electrode current collector layer described later.

[0133] There are no particular limitations on the method for drying and removing the dispersion medium; conventional methods can be used.

[0134] [Battery manufacturing method]

[0135] Batteries can be manufactured by methods including the manufacture of electrode active material layers using the methods disclosed herein.

[0136] The electrode active material layer of the battery obtained in this way has improved ionic conductivity.

[0137] The method for manufacturing the electrode active material layer of this disclosure can be referred to the above description.

[0138] The method of manufacturing a battery may further include stacking an electrode active material layer and the layers that can constitute a battery (described later) to form an electrode stack.

[0139] Other components, such as terminals, are installed within the electrode stack as needed. A battery is obtained by housing the electrode stack within a battery casing and sealing it.

[0140] [Battery]

[0141] The battery has an electrode active material layer manufactured using the method disclosed herein. The battery may sequentially have a negative electrode current collector layer, a negative electrode active material layer, an electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer. In this battery, the negative electrode active material layer or the positive electrode active material layer may be an electrode active material layer manufactured using the method disclosed herein, particularly the negative electrode active material layer may be an electrode active material layer manufactured using the method disclosed herein.

[0142] The battery disclosed herein can be a liquid-based battery or a solid-state battery, and more particularly, a solid-state battery. Regarding this disclosure, a "solid-state battery" refers to a battery that contains at least a solid electrolyte as an electrolyte; therefore, a solid-state battery can also contain a combination of a solid electrolyte and a liquid electrolyte as an electrolyte. Furthermore, a solid-state battery can also be an all-solid-state battery, i.e., a battery that contains only a solid electrolyte as its electrolyte.

[0143] The battery can be a primary battery or a secondary battery, especially a lithium-ion secondary battery.

[0144] The battery can be constrained from both sides of the stacking direction of the aforementioned layers by constraint components such as end plates. As a constraint method, the method of using the constraint torque of bolts can be exemplified, but it is not limited to this.

[0145] The elements that can constitute a battery will be described below. Hereinafter, an example will be given of a case where the battery is an all-solid-state battery and the electrode active material layer manufactured using the method of this disclosure is a negative electrode active material layer.

[0146] [Negative electrode current collector layer]

[0147] The negative electrode current collector layer can be in the form of foil, plate, mesh, perforated metal, or foam. It can be a metal foil or metal mesh, or a carbon sheet, but preferably a metal foil. The negative electrode current collector layer can be composed of multiple foils or sheets.

[0148] There are no particular limitations on the metal constituting the negative electrode current collector layer; examples include copper, nickel, chromium, gold, platinum, silver, aluminum, iron, titanium, zinc, cobalt, or stainless steel. In particular, the negative electrode current collector layer may contain at least one metal selected from copper, nickel, and stainless steel.

[0149] For purposes such as adjusting resistance, any coating can be formed on the surface of the negative electrode current collector layer. Furthermore, the negative electrode current collector layer can be a layer on which the aforementioned metal is deposited or vapor-deposited onto a metal foil or substrate. Additionally, when the negative electrode current collector layer is composed of multiple metal foils, any layer can be formed between these multiple metal foils.

[0150] There is no particular limitation on the thickness of the negative electrode current collector layer. For example, it can be 0.1 μm or more, or 1 μm or more, or less than 1 mm or less than 100 μm.

[0151] [Negative electrode active material layer]

[0152] In the above-described manner, the negative electrode active material layer is an electrode active material layer manufactured using the method of this disclosure. The method of this disclosure for manufacturing the electrode active material layer can be referred to the above description.

[0153] [Solid electrolyte layer]

[0154] The solid electrolyte layer contains solid electrolyte particles and may further contain a binder.

[0155] For information on solid electrolyte particles and binders, please refer to the above description.

[0156] There is no particular limitation on the thickness of the solid electrolyte layer; for example, it can be greater than 0.1 μm and less than 1000 μm.

[0157] [Positive electrode active material layer]

[0158] The positive electrode active material layer contains positive electrode active material, and may further contain solid electrolyte, conductive additives and binders.

[0159] There are no particular limitations on the positive electrode active material; for example, it can be an oxide active material. Oxide active materials used in lithium-ion batteries can be, for example, LiCoO2, LiMnO2, Li2NiMn3O8, LiVO2, and LiCrO2. Alternatively, it can be LiFePO4, LiCoPO4, LiNiO2, or LiNi... 1 / 3 Co 1 / 3 Mn1 / 3 O2. In addition, a coating containing Li ion-conducting oxides such as LiNbO3 can be formed on the surface of these active materials.

[0160] There is no particular limitation on the content of positive electrode active material in the positive electrode active material layer; it can be set appropriately by considering factors such as the desired battery capacity.

[0161] For information on solid electrolytes, conductive additives, and adhesives, please refer to the above description.

[0162] There is no particular limitation on the thickness of the positive electrode active material layer; for example, it can be above 0.1 μm and below 1000 μm.

[0163] [Positive current collector layer]

[0164] The positive current collector layer can be in the form of foil, plate, mesh, perforated metal, or foam. It can be a metal foil or a metal mesh, especially a metal foil. The positive current collector layer can be composed of multiple foils.

[0165] Examples of metals constituting the positive current collector layer include copper, nickel, chromium, gold, platinum, silver, aluminum, iron, titanium, zinc, cobalt, or stainless steel, with aluminum being a particularly important component of the positive current collector layer.

[0166] For purposes such as adjusting resistance, any coating can be formed on the surface of the positive current collector layer. Furthermore, the positive current collector layer can be a layer on which the aforementioned metal is deposited or vapor-deposited onto a metal foil or substrate. Additionally, when the positive current collector layer is composed of multiple metal foils, any layer can be formed between these multiple metal foils.

[0167] There is no particular limitation on the thickness of the positive electrode current collector layer. For example, it can be 0.1 μm or more, or 1 μm or more, or less than 1 mm or less than 100 μm.

[0168] [Other Structures]

[0169] The battery can be formed by housing the aforementioned structures inside an outer casing. The outer casing can be any known type of battery casing. Furthermore, multiple batteries can be arbitrarily electrically connected and stacked to form a battery pack. In this case, the battery pack can be housed inside a known battery casing. The battery can have other obvious structures such as necessary terminals. The battery shape can be, for example, coin-shaped, laminated (pouch-shaped), cylindrical, or square.

[0170] Example 1

[0171] [Fabrication of the Electrode Active Material Layer]

[0172] [Preparation of Solid Electrolyte Slurry]

[0173] 700 mg of LPS glass-ceramic (average particle size: 0.1 μm, specific surface area: 30 m²) as sulfide solid electrolyte particles were added to 4 g of tetrahydronaphthalene as a solvent. 2 / g). Furthermore, 3mg of monolayer CNTs (width: 3nm, diameter: 5μm, specific surface area: 1000m²) were added as a conductive additive. 2 The electrolyte mixture (g) and a predetermined amount of dispersant are ultrasonically dispersed and mixed for 2 minutes. This yields a solid electrolyte slurry.

[0174] [Mixing of porous electrode active material particles with solid electrolyte slurry]

[0175] 700 mg of silicon electrode active material composite particles (average particle size: 10 μm, specific surface area: 150 m²) were added to the obtained solid electrolyte slurry as porous electrode active material particles. 2 / g). Then, 600 mg of a 5% (w / w) tetrahydronaphthalene solution of styrene-butadiene rubber (SBR) as a binder was added, and the mixture was ultrasonically dispersed and mixed for 10 minutes. This yielded an electrode slurry. The obtained electrode slurry was coated onto a nickel (Ni) foil used as a release sheet with a gap of 300 μm to obtain a coating layer. The obtained coating layer was dried at 180 °C for 2 hours. The dried coating layer was then stamped to a size of φ11.28 mm with a surface pressure of 5 t / cm. 2 The material was densified by pressing, thus creating the electrode active material layer of Example 1.

[0176] Comparative Example 1

[0177] Except that the timing of adding the solid electrolyte particles and the silicon electrode active material composite particles was reversed, the electrode active material layer of Comparative Example 1 was obtained in the same manner as in Example 1.

[0178] Comparative Example 2

[0179] Except that all solid components were added at the same time and the ultrasonic dispersion and mixing time was set to the total ultrasonic dispersion and mixing time in Example 1, the electrode active material layer of Comparative Example 2 was obtained in the same manner as in Example 1.

[0180] [evaluate]

[0181] [Particle size in the slurry]

[0182] Each electrode slurry was stretched on a particle size analyzer. Using a grinding particle size scanner (Asahi Research Institute, AGS-100), images of each electrode slurry in this state were captured. The captured images are shown below. Figures 1A-1C ( Figure 1A Compare with Example 1. Figure 1B Example 1, Figure 1C (Comparative Example 2). Based on these images, determine the particle size of the slurry according to the method in JISK 5600-2-5. Figures 1A-1C As shown, the grinding particle size of Example 1 is 40 μm, while the grinding particle size of Comparative Examples 1 and 2 is 50 μm or more. This indicates that in the electrode mixture slurry of Example 1 prepared using the method of this disclosure, there are fewer coarse particles caused by agglomeration, and the particles are well dispersed.

[0183] [Ion conductivity]

[0184] [Reference Unit Creation]

[0185] 200 mg of solid electrolyte particles were introduced into a ceramic cylinder with an opening of φ11.28 mm, at a surface pressure of 5 t / cm². 2 The mixture is densified by pressing to create a solid electrolyte layer. The thickness of the resulting solid electrolyte layer is then measured.

[0186] Lithium foils are stacked on both sides of a solid electrolyte layer, and SUS pins are inserted from the top and bottom of a cylinder to constrain it at 20 MPa. This yields a reference cell. The polarization resistance of the obtained reference cell is measured using a DC polarization method.

[0187] [Creating Evaluation Units]

[0188] 100 mg of solid electrolyte particles were placed into a ceramic cylinder with a diameter of φ11.28, at a surface pressure of 5 t / cm². 2 The mixture was compacted by pressing, and the first solid electrolyte layer was created.

[0189] Each of the electrode active material layers, after the Ni foil was stripped, was stacked on the obtained first solid electrolyte layer. 100 mg of solid electrolyte was then added to the electrode active material layer at a surface pressure of 5 t / cm². 2 The material is densified by pressing to obtain an electrode stack having a first solid electrolyte layer, an electrode active material layer, and a second solid electrolyte layer in sequence. The thickness of the obtained electrode stack is measured.

[0190] Lithium foils are stacked on each of the solid electrolyte layers on both sides of the electrode active material layer, and SUS pins are inserted from the top and bottom of a cylinder to constrain it at 20 MPa. This yields an evaluation cell. The polarization resistance of the obtained evaluation cell is measured using a DC polarization method.

[0191] [Calculation of ionic conductivity]

[0192] The polarization resistance R of the electrode active material layer is calculated based on the difference in polarization resistance between the evaluation unit and the reference unit. Furthermore, the thickness L of the electrode active material layer is calculated based on the difference in thickness between the evaluation unit and the reference unit. The ionic conductivity of the electrode active material layer is calculated using the formula σ = L / (S×R), where S is the area of ​​the electrode active material layer and σ is the ionic conductivity. The results are shown below. Figure 2 .

[0193] like Figure 2 As shown, the electrode active material layer of Example 1, manufactured using the method of this disclosure, exhibits high ionic conductivity.

Claims

1. A method for manufacturing an electrode mixture slurry, comprising the following steps: Solid electrolyte particles, dispersants, and solvents are mixed to prepare a solid electrolyte slurry; and The porous electrode active material particles are mixed with the solid electrolyte slurry. Furthermore, the following relations 1 and 2 are satisfied. Equation 1: The specific surface area of ​​the porous electrode active material particles is greater than the specific surface area of ​​the solid electrolyte particles. Equation 2: The average particle size of the porous electrode active material particles is greater than the average particle size of the solid electrolyte particles.

2. The method for manufacturing the electrode mixture slurry according to claim 1, The porous electrode active material particles are composite particles of electrode active materials, and The electrode active material composite particles are secondary particles formed from multiple primary electrode active material particles and having multiple fine pores between the primary electrode active material particles.

3. The method for manufacturing the electrode mixture slurry according to claim 2, The ratio of the specific surface area of ​​the porous electrode active material particles to the specific surface area of ​​the solid electrolyte particles is S. AM / S SE 1 < S AM / S SE ≤10, and / or The ratio of the average particle size of the porous electrode active material particles to the average particle size of the solid electrolyte particles is d. AM / d SE For 50≤d AM / d SE ≤200.

4. The method for manufacturing the electrode mixture slurry according to claim 3, The specific surface area of ​​the porous electrode active material particles is 50 m². 2 / g~300m 2 / g, and the specific surface area of ​​the solid electrolyte particles is 10m². 2 / g~100m 2 / g, and / or The average particle size of the porous electrode active material particles is 1 μm to 20 μm, and the average particle size of the solid electrolyte particles is 0.01 μm to 1 μm.

5. A method for manufacturing an electrode active material layer, comprising the following steps: The electrode mixture slurry is manufactured using the manufacturing method of any one of claims 1 to 4; and The electrode mixture slurry is coated onto a substrate, and then the solvent is dried and removed.

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