Method for manufacturing electrode active material layer, electrode active material layer, and battery

Abstract

This disclosure provides a method for manufacturing an electrode active material layer capable of mitigating the effects of expansion and contraction of alloy-based electrode active materials, an electrode active material layer, and a battery. The method for manufacturing the electrode active material layer includes the following steps: providing an electrode composite slurry containing alloy-based electrode active material particles, wherein the ratio of the d50 particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer is 0.10 to 0.50; using first and second doctor blades having concave and convex surfaces extending in the width direction of the electrode active material layer, respectively, the electrode composite slurry is doctor-coated onto first and second substrates to form first and second pre-electrode active material layers having multiple first and second thick film portions and first and second thin film portions; and stacking the first and second pre-electrode active material layers with the first thick film portion facing the second thin film portion and the first thin film portion facing the second thick film portion respectively.

Description

Technical Field

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

[0002] As disclosed in Patent Document 1, it is known that alloy-based electrode active materials such as silicon and tin expand and contract during the charging and discharging of a battery.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-121557 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The purpose of this disclosure is to provide a method for manufacturing an electrode active material layer that can mitigate the effects of expansion and contraction of alloy-based electrode active materials, an electrode active material layer, and a battery.

[0008] Methods for solving problems

[0009] The author of this application has discovered that the above-mentioned problems can be solved by using the following methods.

[0010] <Option 1>

[0011] A method for manufacturing an electrode active material layer includes the following steps:

[0012] An electrode slurry comprising alloy-based electrode active material particles and a dispersion medium is provided, wherein the ratio of the d50 particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer is 0.10 to 0.50.

[0013] Using a first scraper with concave and convex shapes extending in the width direction of the electrode active material layer, the electrode composite slurry is coated onto a first substrate, thereby forming a first pre-electrode active material layer having a plurality of first thick film portions and a plurality of first thin film portions on the first substrate.

[0014] Using a second doctor blade having irregularities extending in the width direction of the electrode active material layer, the electrode composite slurry is coated onto a second substrate, thereby forming a second preliminary electrode active material layer having a plurality of second thick film portions and a plurality of second thin film portions on the second substrate; and

[0015] The first thick film portion and the second thin film portion, as well as the first thin film portion and the second thick film portion, are respectively positioned opposite each other, and the first pre-electrode active material layer and the second pre-electrode active material layer are stacked.

[0016] <Option 2>

[0017] According to the method described in Scheme 1, the d50 particle size of the alloy-based electrode active material particles is 5μm to 15μm, and the thickness of the electrode active material layer is 10μm to 100μm.

[0018] <Option 3>

[0019] The electrode active material layer is an electrode active material layer containing alloy-based electrode active material particles. In a cross-sectional SEM image, the ratio of the average particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer is 0.20 to 1.0. The average particle size of the alloy-based electrode active material particles is the average of the particle sizes of at least five alloy-based electrode active material particles extracted sequentially from the largest particle in the cross-sectional SEM image. The cross-sectional SEM image is an image of the electrode active material layer with a width of 2.3 times the thickness of the electrode active material layer. In the cross-sectional SEM image, the difference between the maximum and minimum area ratios of the alloy-based electrode active material particles in the 12 imaginary 12-divided regions along the width direction of the electrode active material layer is less than 0.40.

[0020] <Option 4>

[0021] According to the electrode active material layer of Scheme 3, the difference is less than 0.25.

[0022] <Option 5>

[0023] According to the electrode active material layer of Scheme 3 or 4, the interquartile range of the area ratio of the alloy-based electrode active material particles is less than 0.15 in each distinct region of the cross-sectional SEM image.

[0024] <Option 6>

[0025] According to any one of Schemes 3 to 5, in the electrode active material layer, the dispersion (variance) of the area ratio of the alloy-based electrode active material particles between the distinct regions of the cross-sectional SEM image is less than 0.015.

[0026] <Option 7>

[0027] According to any one of Schemes 3 to 6, the maximum value of the ratio of the area ratio of the alloy-based electrode active material particles in the entire cross-sectional SEM image to the area ratio of the alloy-based electrode active material particles in each distinct region of the cross-sectional SEM image is 0.70 or more.

[0028] <Option 8>

[0029] The electrode active material layer according to any one of Schemes 3 to 7, wherein the alloy-based electrode active material particles are silicon electrode active material particles.

[0030] <Option 9>

[0031] According to any one of Schemes 3 to 8, the electrode active material layer, wherein the alloy-based electrode active material particles are secondary particles comprising a plurality of primary electrode active material particles.

[0032] <Option 10>

[0033] According to the electrode active material layer of Scheme 9, the secondary particles further include a binder.

[0034] <Option 11>

[0035] A battery comprising an electrode active material layer according to any one of embodiments 3 to 10.

[0036] <Option 12>

[0037] The battery described in Scheme 11 is a solid-state battery.

[0038] Invention Effects

[0039] According to this disclosure, a method for manufacturing an electrode active material layer that can mitigate the effects of expansion and contraction of alloy-based electrode active materials, an electrode active material layer, and a battery can be provided. Attached Figure Description

[0040] Figure 1 (a) A schematic cross-sectional view illustrating the method for forming the active material layer of the first pre-electrode. Figure 1 (b) A schematic cross-sectional view illustrating the method for forming the active material layer of the second pre-electrode. Figure 1 (c) A schematic cross-sectional view illustrating the method of stacking the first pre-electrode active material layer and the second pre-electrode active material layer. Figure 1 (d) A schematic cross-sectional view showing an example of an electrode active material layer manufactured using the method of this disclosure.

[0041] Figure 2 Histograms showing the area ratios of alloy-based electrode active material particles in 12 distinct regions for examples and comparative examples.

[0042] Figure 3 A graph showing the increase in constraint pressure of the batteries in the embodiments and comparative examples.

[0043] Explanation of reference numerals in the attached figures

[0044] 1. Alloy-based electrode active material particles

[0045] 10 Electrode active material layer

[0046] 110 First Preparatory Electrode Active Material Layer

[0047] 111 First Thick Film Section

[0048] 112 First Thin Film Section

[0049] 120 First substrate

[0050] 130 First scraper

[0051] 210 Second Preparatory Electrode Active Material Layer

[0052] 211 Second Thick Film Section

[0053] 212 Second Thin Film Section

[0054] 220 Second substrate

[0055] 230 Second scraper Detailed Implementation

[0056] The embodiments of this disclosure are described in detail below. It should be noted that this disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the disclosure's intent.

[0057] <<Method for Manufacturing Electrode Active Material Layer>>

[0058] The method of manufacturing an electrode active material layer of the present disclosure includes the following steps: providing an electrode composite slurry comprising alloy-based electrode active material particles and a dispersion medium, wherein the ratio of the d50 particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer is 0.10 to 0.50; applying the electrode composite slurry to a first substrate using a first doctor blade having irregularities extending in the width direction of the electrode active material layer, thereby forming a first preliminary electrode active material layer having a plurality of first thick film portions and a plurality of first thin film portions on the first substrate; applying the electrode composite slurry to a second substrate using a second doctor blade having irregularities extending in the width direction of the electrode active material layer, thereby forming a second preliminary electrode active material layer having a plurality of second thick film portions and a plurality of second thin film portions on the second substrate; and stacking the first preliminary electrode active material layer and the second preliminary electrode active material layer with the first thick film portions facing the second thin film portions and the first thin film portions facing the second thick film portions respectively.

[0059] The author of this application believes that by arranging multiple alloy-based electrode active material particles with relatively large particle sizes in an overlapping manner along the thickness direction of the electrode active material layer, localized areas may arise in the width direction of the electrode active material layer where the expansion and contraction effects of the alloy-based electrode active material particles are amplified. This problem is considered particularly significant when the ratio of the d50 particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer (hereinafter sometimes abbreviated as "d50 particle size / thickness value") is relatively large.

[0060] In this regard, the present applicant has discovered that, according to the method described above, it is possible to manufacture an electrode active material layer that mitigates the effects of expansion and contraction of the alloy-based electrode active material. The reasoning is not intended to be bound by any theory, but is as follows: Consider a pre-formed electrode active material layer formed by coating with a doctor blade having uneven surfaces, in which alloy-based electrode active material particles with larger particle sizes are disposed in the thick film portion, and alloy-based electrode active material particles with smaller particle sizes are disposed in the thin film portion. Furthermore, it is believed that by stacking a pair of pre-formed electrode active material layers having such thick and thin film portions opposite each other, it is possible to arrange alloy-based electrode active material particles with larger particle sizes in a manner that prevents overlap in the thickness direction of the electrode active material layer. Therefore, it is believed that even when the d50 particle size / thickness value is relatively large, it is possible to suppress the formation of regions where the effects of expansion and contraction of the alloy-based electrode active material particles locally increase in the width direction of the electrode active material layer.

[0061] Regarding this disclosure, the "electrode active material layer" can be a "positive electrode active material layer" or a "negative electrode active material layer," and in particular, it can be a "negative electrode active material layer." Therefore, the "electrode active material" can be a "positive electrode active material" or a "negative electrode active material," and in particular, it can be a "negative electrode active material."

[0062] The method for manufacturing the electrode active material layer of this disclosure will now be described with reference to the accompanying drawings. Furthermore, the dimensional relationships in the drawings do not reflect actual dimensional relationships.

[0063] <Pulp Supply>

[0064] The method disclosed herein includes providing an electrode slurry comprising alloy-based electrode active material particles and a dispersion medium.

[0065] Regarding this disclosure, "electrode composite" means a composition that can form an electrode active material layer, either directly or through other components. Additionally, regarding this disclosure, "electrode composite slurry" means a slurry that, in addition to "electrode composite," also contains a dispersion medium, thereby enabling coating and drying to form an electrode active material layer.

[0066] Regarding this disclosure, "electrode composite" can be "positive electrode composite" or "negative electrode composite", and in particular, it can be "negative electrode composite".

[0067] For alloy-based electrode active material particles, refer to the following description relating to the electrode active material layer of this disclosure.

[0068] As a dispersion medium, there are no particular limitations as long as it can disperse the active material particles of the alloy electrode.

[0069] In the method disclosed herein, the ratio of the d50 particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer is 0.10 to 0.50. When this ratio is within the above range, that is, when the d50 particle size of the alloy-based electrode active material particles is relatively large relative to the thickness of the electrode active material layer, the effect of expansion and contraction of the alloy-based electrode active material particles is particularly significant. Therefore, it is significant to manufacture the electrode active material layer using the method disclosed herein.

[0070] The ratio can be 0.15 to 0.45, or 0.20 to 0.40. The ratio can be 0.10 or higher, 0.15 or higher, 0.20 or higher, 0.25 or higher, or 0.30 or higher. Alternatively, it can be 0.50 or lower, 0.45 or lower, or 0.40 or lower, or 0.35 or lower.

[0071] In the method disclosed herein, the d50 particle size of the alloy-based electrode active material particles is 5 μm to 15 μm, and the thickness of the electrode active material layer can be 10 μm to 100 μm.

[0072] In the method disclosed herein, the d50 particle size of the alloy-based electrode active material particles can be 5 μm to 15 μm, 6 μm to 12 μm, or 7 μm to 10 μm. This d50 particle size can be 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more; alternatively, it can be 15 μm or less, 12 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, or 5 μm or less. When the d50 particle size is within the above-mentioned range, the method disclosed herein is of great significance in manufacturing the electrode active material layer.

[0073] The d50 particle size of the active material particles in the alloy electrode can be determined using a laser diffraction / scattering particle size distribution measuring device (Partica LA-960V2, manufactured by HORIBA Co., Ltd.).

[0074] In the method of this disclosure, the thickness of the electrode active material layer can be 10 μm to 100 μm, 20 μm to 75 μm, or 25 μm to 50 μm. The thickness of the electrode active material layer can be 10 μm or more, 15 μm or more, 20 μm or more, or 25 μm or more; alternatively, it can be 100 μm or less, 75 μm or less, 50 μm or less, 40 μm or less, or 30 μm or less. When the thickness is within the above-mentioned range, the method of this disclosure is of great significance in manufacturing the electrode active material layer.

[0075] The thickness of the electrode active material layer can be determined from a cross-sectional SEM image of the electrode active material layer taken using a scanning electron microscope (SEM).

[0076] <Formation of the first preparatory electrode active material layer>

[0077] Figure 1 (a) A schematic diagram illustrating the method for forming the first pre-electrode active material layer 110. Figure 1 As illustrated in (a), the method of this disclosure includes: applying an electrode composite slurry to a first substrate 120 using a first scraper 130 having irregularities extending in the width direction of the electrode active material layer, thereby forming a first preliminary electrode active material layer 110 having a plurality of first thick film portions 111 and a plurality of first thin film portions 112 on the first substrate 120. Thus, in the first preliminary electrode active material layer 110, alloy-based electrode active material particles 1 with relatively large particle sizes are disposed in the plurality of first thick film portions 111, and alloy-based electrode active material particles 1 with relatively small particle sizes are disposed in the plurality of first thin film portions 112.

[0078] Regarding this disclosure, the "first thick film portion" is the portion formed by the recess of the first scraper 130, and the "first thin film portion" is the portion formed by the protrusion of the first scraper 130.

[0079] exist Figure 1 In (a), the alloy-based electrode active material particles 1 with relatively large particle sizes are schematically shown as coarse particles. Multiple alloy-based electrode active material particles with relatively large particle sizes may be present in the first thick film portion 111. Furthermore, although not shown, multiple alloy-based electrode active material particles with relatively small particle sizes may be present in the first thin film portion 112. It should be noted that in... Figure 1 In (a), for clarity, the reference numerals for the alloy-based electrode active material particle 1, the first thick film portion 111, and the first thin film portion 112 are shown only in one place. The above refers to the descriptions to be provided later. Figure 1 The same applies to the alloy-based electrode active material particles 1, the second thick film portion 211, and the second thin film portion 212 in (b).

[0080] The height of the gap between the concave and convex portions of the first scraper 130, i.e., the distance from the first substrate 120, is not particularly limited, and can be appropriately set considering the size of the alloy-based electrode active material particles 1 and the thickness of the electrode active material layer 10. For example, the height of the gap in the concave portion of the first scraper 130 can be larger than the d50 and / or d90 particle size of the alloy-based electrode active material particles 1. Conversely, the height of the gap in the convex portion of the first scraper 130 can be smaller than the d50 and / or d10 particle size of the alloy-based electrode active material particles 1. The same applies to the height of the gap between the concave and convex portions of the second scraper 230, which will be described later.

[0081] There is no particular limitation on the width of the concave and convex portions of the first scraper 130; they can be appropriately set considering factors such as the size of the alloy-based electrode active material particles 1 used. For example, the width of the concave portion of the first scraper 130 can be larger than the d50 and / or d90 particle size of the alloy-based electrode active material particles 1. The same applies to the widths of the concave and convex portions of the second scraper 230, which will be described later.

[0082] The first scraper 130 has an uneven cross-sectional shape as follows: Figure 1 As illustrated in (a), the shape can be a straight line, but it is not limited to that; it can also be a curve. The same applies to the cross-sectional shape of the second scraper 230, which will be described later.

[0083] There are no particular limitations on the thickness, shape, and number of the first thick film portion 111 and the first thin film portion 112. They can be adjusted according to the height of the gap between the concave and convex portions of the first scraper 130, the cross-sectional shape of the concave and convex portions of the first scraper 130, and the number of concave and convex portions of the first scraper 130. The same applies to the thickness, shape, and number of the second thick film portion 211 and the second thin film portion 212, which will be described later.

[0084] The first substrate 120 is not particularly limited; for example, it can be a current collector layer or a release sheet. For the current collector layer, refer to the description of the negative and positive current collector layers below. The release sheet is not particularly limited; for example, it can be a polymer foil made of materials such as polyethylene terephthalate (PET) or a metal foil made of materials such as aluminum. The same applies to the cross-sectional shape of the second substrate 220, which will be described later.

[0085] When the first substrate 120 or the second substrate 220 is a current collector layer, the second substrate 220 or the first substrate 120 may be a release sheet. In this case, by peeling the release sheet from the second substrate 220 or the first substrate 120, a laminate of the electrode active material layer 10 and the current collector layer manufactured using the method of this disclosure can be obtained.

[0086] When both the first substrate 120 and the second substrate 220 are release sheets, the electrode active material layer is transferred to the current collector layer by peeling off the release sheet of one of them, and then the release sheet of the other is peeled off, thereby obtaining a laminate of the electrode active material layer 10 and the current collector layer manufactured by the method of this disclosure.

[0087] <Formation of the second preparatory electrode active material layer>

[0088] Figure 1 (b) A schematic diagram illustrating the method for forming the second pre-electrode active material layer 210. Figure 1 As illustrated in (b), the method of this disclosure includes: applying an electrode composite slurry to a second substrate 220 using a second scraper 230 having irregularities extending in the width direction of the electrode active material layer, thereby forming a second preliminary electrode active material layer 210 having a plurality of second thick film portions 211 and a plurality of second thin film portions 212 on the second substrate 220. Thus, in the second preliminary electrode active material layer 210, alloy-based electrode active material particles 1 with relatively large particle sizes are disposed in the plurality of second thick film portions 211, and alloy-based electrode active material particles 1 with relatively small particle sizes are disposed in the plurality of second thin film portions 212.

[0089] Regarding this disclosure, the "second thick film portion" is the portion formed by the recess of the second scraper 230, and the "second thin film portion" is the portion formed by the protrusion of the second scraper 230.

[0090] like Figure 1 As illustrated in (b), the second scraper 230 may have a first scraper 130 and a pair of protrusions and depressions, thereby forming a pair of first thick film portions 111 and second thin film portions 212, and first thin film portions 112 and second thick film portions 211, respectively, in the first pre-electrode active material layer 110 and the second pre-electrode active material layer 210. However, in the following description of the stacking of the first and second pre-electrode active material layers, as long as the first thick film portion 111 and the second thin film portion 212, and the first thin film portion 112 and the second thick film portion 211, are respectively opposite to each other when the first pre-electrode active material layer 110 and the second pre-electrode active material layer 210 are stacked, this disclosure is not limited to the second scraper 230 having a first scraper 130 and a pair of protrusions and depressions.

[0091] <Layering of the first and second pre-electrode active material layers>

[0092] The method disclosed herein includes: stacking a first pre-electrode active material layer 110 and a second pre-electrode active material layer 210 such that a first thick film portion 111 and a second thin film portion 212, and a first thin film portion 112 and a second thick film portion 211 are respectively opposite to each other. It is believed that by stacking the first pre-electrode active material layer 110 and the second pre-electrode active material layer 210 in this way, alloy-based electrode active material particles 1 with relatively large particle sizes can be arranged in a manner that does not overlap in the thickness direction of the electrode active material layer 10. Therefore, even when the d50 particle size / thickness value is relatively large, it is possible to suppress the localized increase in the effect of expansion and contraction of the alloy-based electrode active material particles 1 in the width direction of the electrode active material layer 10.

[0093] <Other Operations>

[0094] The method disclosed herein may further include: after the first pre-electrode active material layer 110 and the second pre-electrode active material layer 210 are stacked, further operations such as pressing and drying are performed. That is, in order to improve the adhesion between the first pre-electrode active material layer 110 and the second pre-electrode active material layer 210, they can be pressed, and the residual dispersion medium in the electrode active material layer 10 can be dried and removed.

[0095] <<Electrode Active Material Layer>>

[0096] The electrode active material layer of this disclosure comprises alloy-based electrode active material particles. In the electrode active material layer of this disclosure, in a cross-sectional SEM image, the ratio of the average particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer is 0.20 to 1.0. The average particle size of the alloy-based electrode active material particles is the average of the particle sizes of at least five alloy-based electrode active material particles sequentially extracted from the largest particle in the cross-sectional SEM image, and the cross-sectional SEM image is an image of the electrode active material layer with a width of 2.3 times the thickness of the electrode active material layer. In the cross-sectional SEM image, among the 12 imaginary regions divided into 12 equal parts in the width direction of the electrode active material layer, the difference between the maximum and minimum area ratios of the alloy-based electrode active material particles is 0.40 or less.

[0097] When the ratio of the specified average particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer (hereinafter sometimes abbreviated as "specified average particle size / thickness value") is relatively large, it is considered that by arranging multiple alloy-based electrode active material particles with relatively large particle sizes in an overlapping manner in the thickness direction of the electrode active material layer, a localized increase in the effect of expansion and contraction of the alloy-based electrode active material particles is easily generated in the width direction of the electrode active material layer.

[0098] In this regard, the present applicant has discovered that the electrode active material layer of this disclosure can mitigate the effects of expansion and contraction of the alloy-based electrode active material. The rationale, without being bound by any theory, is as follows: That is, a smaller difference between the maximum and minimum area ratios of the alloy-based electrode active material particles among the aforementioned distinct regions in a specified cross-sectional SEM image indicates that the alloy-based electrode active material particles are relatively uniformly present within the electrode active material layer. Therefore, it is believed that even when the specified average particle size / thickness value is relatively large, it is possible to suppress areas where the effects of expansion and contraction of the alloy-based electrode active material particles locally increase, along the width direction of the electrode active material layer.

[0099] <Alloy-based electrode active material particles>

[0100] The electrode active material layer disclosed herein comprises alloy-based electrode active material particles. These alloy-based electrode active material particles expand and contract during the charging and discharging of the battery.

[0101] In the electrode active material layer of this disclosure, the alloy-based electrode active material particles can be primary electrode active material particles or secondary particles containing multiple primary electrode active material particles.

[0102] The active material particles of the alloy-based electrode can particularly be the aforementioned secondary particles. This makes it easy to make the d50 particle size and the aforementioned average particle size of the active material particles within a preferred range. Furthermore, the gaps between primary particles can mitigate the effects of expansion and contraction of the active material particles. There are no particular limitations on the number, porosity, or size of the gaps in the secondary particles; they can be appropriately set considering the magnitude of expansion and contraction of the active material. Additionally, the d50 particle size of the primary particles can be appropriately set considering the desired d50 particle size of the secondary particles and the aforementioned average particle size.

[0103] There are no particular limitations on the active material particles used in alloy-based electrodes; for example, they can be active material particles of silicon alloy-based electrodes or active material particles of tin alloy-based electrodes.

[0104] Examples of materials that can be used as active material particles for silicon alloy electrodes include silicon (silicon), silicon oxide, silicon carbide, silicon nitride, or their solid solutions.

[0105] Examples of materials that can be used as active material particles for tin alloy electrodes include tin, tin oxides, tin nitrides, or their solid solutions.

[0106] In the electrode active material layer disclosed herein, the material of the silicon alloy-based electrode active material particles can be silicon. That is, the alloy-based electrode active material particles can be silicon electrode active material particles.

[0107] When the active material particles of the alloy-based electrode are silicon primary active material particles, there are no particular limitations on its composition as long as it contains silicon. The proportion of silicon in all elements contained in this 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. This 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. This primary particle may contain silicon oxides.

[0108] 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.

[0109] The primary particles of silicon electrode active material can be porous silicon electrode active material particles. That is, the primary particles of silicon electrode active material can have multiple micropores. Therefore, when the active material particles of the alloy system electrode are secondary particles, not only the voids within the secondary particles, but also the micropores of silicon can mitigate the effects of silicon expansion and contraction. There are no particular limitations on the number of micropores, micropore volume, and micropore diameter of the primary particles of porous silicon electrode active material; they can be appropriately set considering the magnitude of silicon expansion and contraction. The micropore diameter can be, for example, at the nanometer scale.

[0110] When the active material particles of the alloy-based electrode are secondary particles, the secondary particles may further contain a binder. The binder can bond multiple primary particles of the alloy-based electrode active material together.

[0111] As an adhesive, there are no particular limitations; for example, it can be a butadiene rubber (BR) based adhesive, an acrylate butadiene rubber (IIR) based adhesive, an acrylate butadiene rubber (ABR) based adhesive, a styrene butadiene rubber (SBR) based adhesive, a polyvinylidene fluoride (PVdF) based adhesive, a polytetrafluoroethylene (PTFE) based adhesive, a polyimide (PI) based adhesive, a carboxymethyl cellulose (CMC) based adhesive, a polyacrylate based adhesive, a polyacrylate based adhesive, or a combination thereof.

[0112] There is no particular limitation on the content of the adhesive in the aforementioned secondary particles; it can be appropriately set considering the required adhesion, etc.

[0113] For example, a method including the following steps can be used to manufacture secondary particles of alloy-based electrode active materials:

[0114] Provides a slurry containing primary particles of alloy-based electrode active material and a dispersion medium; and

[0115] Spray drying is used to remove the dispersion medium.

[0116] For primary particles of active materials in alloy-based electrodes, please refer to the above description.

[0117] As a dispersion medium, there are no particular limitations as long as it can disperse the active material of the alloy electrode in a single step.

[0118] When the secondary particles of the alloy-based electrode active material also contain a binder, there are no particular limitations on the dispersion medium, as long as it can disperse the primary particles of the alloy-based electrode active material and dissolve or disperse the binder. By further containing the binder in the above-mentioned slurry, it is possible to manufacture secondary particles of the alloy-based electrode active material that also contain a binder.

[0119] For adhesives, please refer to the above description.

[0120] By adjusting the concentration of solid components in the slurry, the slurry feed rate, spray pressure, and drying temperature during spray drying, the d50 particle size and the average particle size specified above for the active material particles in the alloy electrode can be controlled.

[0121] There is no particular limitation on the content of alloy-based electrode active material particles in the electrode active material layer; it can be appropriately set considering factors such as the required battery capacity.

[0122] <Other Ingredients>

[0123] The electrode active material layer of this disclosure may optionally further include solid electrolytes, conductive additives, binders, etc. When the electrode active material layer of this disclosure is manufactured using the method of this disclosure, the electrode composite slurry, in addition to the alloy-based electrode active material particles and the dispersion medium, contains other components, thereby obtaining an electrode active material layer that also contains other components.

[0124] (Solid electrolyte)

[0125] Examples of solid electrolytes 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 electrolytes are particularly noteworthy.

[0126] For example, in the case of a lithium-ion secondary battery, the solid electrolyte can have lithium-ion conductivity.

[0127] Examples of sulfide solid electrolytes with lithium-ion conductivity include those containing Li, X (where X is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In), and S. Furthermore, sulfide solid electrolytes may further contain at least one of O and a halogen element. Examples of halogen elements include F, Cl, Br, and I.

[0128] Examples of sulfide solid electrolytes include Li₂S-P₂S₅, Li₂S-P₂S₅-LiI, Li₂S-P₂S₅-GeS₂, Li₂S-P₂S₅-Li₂O, Li₂S-P₂S₅-Li₂O-LiI, Li₂S-P₂S₅-LiI-LiBr, Li₂S-SiS₂, Li₂S-SiS₂-LiI, Li₂S-SiS₂-LiBr, Li₂S-SiS₂-LiCl, Li₂S-SiS₂-B₂S₃-LiI, Li₂S-SiS₂-P₂S₅-LiI, Li₂S-B₂S₃, Li₂S-P₂S₅-ZmSn (where m and n are positive numbers, and Z is any one of Ge, Zn, or Ga), Li₂S-GeS₂, Li₂S-SiS₂-Li₃PO₄, and Li₂S-SiS₂-Li x MO y (Where x and y are positive numbers. M is any one of P, Si, Ge, B, Al, Ga, and In).

[0129] As an oxide solid electrolyte with lithium-ion conductivity, examples include solid electrolytes containing the elements Li, Y (where Y is at least one of Nb, B, Al, Si, P, Ti, Zr, Mo, W, and S), and O. 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 electrolytes; perovskite-type solid electrolytes such as (Li,La)TiO3, (Li,La)NbO3, and (Li,Sr)(Ta,Zr)O3; NASICON-type solid electrolytes such as Li(Al,Ti)(PO4)3 and Li(Al,Ga)(PO4)3; Li-PO solid electrolytes such as Li3PO4 and LIPON (a compound in which part of the O in Li3PO4 is replaced by N); and Li-BO solid electrolytes such as Li3BO3 and a compound in which part of the O in Li3BO3 is replaced by C.

[0130] There are no particular limitations on the content of solid electrolyte in the electrode active material layer; it can be appropriately set considering the required ion conductivity, etc.

[0131] (Conductive additive)

[0132] The conductive additive can be, for example, carbon materials, metal particles, or combinations thereof. Carbon materials can be, for example, 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.

[0133] There is no particular limitation on the content of conductive additives in the electrode active material layer; it can be appropriately set considering the required conductivity, etc.

[0134] (Adhesive)

[0135] The adhesives may be, for example, rubber-based adhesives such as butadiene rubber, hydrogenated butadiene rubber, styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber, nitrile butadiene rubber, hydrogenated nitrile butadiene 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.

[0136] There is no particular limitation on the content of the binder in the electrode active material layer; it can be appropriately determined by taking into account the desired adhesion and other factors.

[0137] The electrode active material layer may further contain components other than those mentioned above, or it may not contain any of them.

[0138] <Various parameters>

[0139] In the electrode active material layer of this disclosure, the ratio of the average particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer in a cross-sectional SEM image is 0.20 to 1.0. The average particle size of the alloy-based electrode active material particles is the average particle size of at least five alloy-based electrode active material particles sequentially extracted from the largest particle in the cross-sectional SEM image, and the cross-sectional SEM image is an image of the electrode active material layer with a width 2.3 times the thickness of the electrode active material layer. When this ratio is within the above range, i.e., when the average particle size of the alloy-based electrode active material particles is relatively large relative to the thickness of the electrode active material layer, the effect of expansion and contraction of the alloy-based electrode active material particles is particularly significant. Therefore, using the electrode active material layer of this disclosure is advantageous.

[0140] The ratio of the average particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer can be 0.20–0.80, 0.25–0.60, or 0.30–0.40. This ratio can be 0.20 or more, 0.25 or more, or 0.30 or more, and can also be 0.80 or less, 0.60 or less, 0.50 or less, 0.45 or less, or 0.35 or less.

[0141] The average particle size of the active material particles in the alloy electrode can be 5μm or more, 7μm or more, 8μm or more, 9μm or more, or 10μm or more. Alternatively, it can be 20μm or less, 17μm or less, 15μm or less, 13μm or less, 11μm or less, or 10μm or less.

[0142] The thickness of the electrode active material layer can be referred to the above description.

[0143] In the electrode active material layer disclosed herein, in a cross-sectional SEM image, the difference between the maximum and minimum area ratios of alloy-based electrode active material particles among the 12 imaginary 12-divided regions along the width direction of the electrode active material layer is less than 0.40. This difference being within the aforementioned range indicates that the alloy-based electrode active material particles are relatively uniformly present within the electrode active material layer. Therefore, such an electrode active material layer can mitigate the effects of expansion and contraction of the alloy-based electrode active material particles.

[0144] The difference between the maximum and minimum area ratio of the active material particles in the aforementioned alloy-based electrode can be 0, greater than 0, greater than 0.01, greater than 0.05, greater than 0.10, greater than 0.15, or greater than 0.20; or less than 0.35, less than 0.30, less than 0.25, or less than 0.23. This effectively mitigates the effects of expansion and contraction of the active material particles in the alloy-based electrode.

[0145] By analyzing the cross-sectional SEM images with 12 distinct regions using the image processing software Image-J (Ver. 1.54f), the area ratio of alloy electrode active material particles in each of the 12 distinct regions can be calculated.

[0146] In the cross-sectional SEM image, the interquartile range of the area ratio of active material particles in the alloy electrode can be below 0.15 across different regions. This interquartile range can be 0, greater than 0, greater than 0.01, or greater than 0.05, and can also be below 0.15, below 0.12, below 0.10, or below 0.08. This effectively mitigates the effects of expansion and contraction of the active material particles in the alloy electrode.

[0147] Furthermore, regarding this disclosure, "interquartile range" refers to the deviation from the central value; therefore, the smaller the value, the better.

[0148] In the cross-sectional SEM image, the area ratio of the active material particles in the alloy electrode can be dispersed to less than 0.015 across different regions. This dispersion can be 0, greater than 0, greater than 0.001, greater than 0.002, greater than 0.003, greater than 0.004, or greater than 0.005; or less than 0.015, less than 0.012, less than 0.010, less than 0.009, less than 0.008, less than 0.007, or less than 0.006. This effectively mitigates the effects of expansion and contraction of the active material particles in the alloy electrode.

[0149] Furthermore, in this disclosure, "dispersion" means deviation from the average value, and therefore, the smaller the value, the better.

[0150] The area ratio of active material particles of alloy electrodes in the entire cross-sectional SEM image can be 0.30 or higher, 0.40 or higher, 0.45 or higher, or 0.50 or higher. Alternatively, it can be 0.70 or lower, 0.60 or lower, or 0.55 or lower.

[0151] The maximum area ratio of alloy-based electrode active material particles in each region of the cross-sectional SEM image can be 0.55 or higher, 0.60 or higher, or 0.65 or higher; alternatively, it can be 0.75 or lower, or 0.70 or lower. This effectively mitigates the effects of expansion and contraction of the alloy-based electrode active material particles.

[0152] The maximum value of the ratio of the area ratio of alloy-based electrode active material particles in the entire cross-sectional SEM image to the area ratio of alloy-based electrode active material particles in each distinct region of the cross-sectional SEM image can be 0.70 or higher. This value can be 0.70 or higher, 0.71 or higher, 0.72 or higher, 0.73 or higher, or 0.74 or higher; alternatively, it can be 0.90 or lower, 0.85 or lower, 0.80 or lower, or 0.75 or lower. This effectively mitigates the effects of expansion and contraction of the alloy-based electrode active material particles.

[0153] The electrode active material layer disclosed herein can be manufactured using the method disclosed herein for manufacturing electrode active material layers.

[0154] <<Battery>>

[0155] The battery disclosed herein includes the electrode active material layer of this disclosure. The battery of this disclosure 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 the battery of this disclosure, the positive electrode active material layer or the negative electrode active material layer may be the electrode active material layer of this disclosure; specifically, the negative electrode active material layer may be the electrode active material layer of this disclosure.

[0156] 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, "solid-state battery" means a battery that contains at least a solid electrolyte as an electrolyte; therefore, a solid-state battery can contain a combination of a solid electrolyte and a liquid electrolyte as an electrolyte. Additionally, a solid-state battery can be an all-solid-state battery, that is, a battery that contains only a solid electrolyte as an electrolyte.

[0157] The battery disclosed herein can be a secondary battery, and in particular, it can be a lithium-ion secondary battery.

[0158] The battery disclosed herein can be constrained on both sides of the stacking direction of the aforementioned layers by end plates or other constraint members. Examples of constraint methods include using the constraint torque of bolts, but it is not limited to these.

[0159] The elements constituting the battery of this disclosure will now be described. Hereinafter, examples will be shown where the battery of this disclosure is an all-solid-state battery and where the electrode active material layer of this disclosure is the negative electrode active material layer.

[0160] <Negative current collector layer>

[0161] The negative electrode current collector layer can be in the form of foil, plate, screen, perforated metal, foam, etc. It can be a metal foil or metal screen, or a carbon sheet; particularly, it can be a metal foil. The negative electrode current collector layer can be composed of multiple foils or sheets.

[0162] There are no particular limitations on the metal constituting the negative electrode current collector layer; for example, it can be copper, nickel, chromium, gold, platinum, silver, aluminum, iron, titanium, zinc, cobalt, stainless steel, etc. In particular, the negative electrode current collector layer may contain at least one metal selected from copper, nickel, and stainless steel.

[0163] To adjust resistance, etc., a coating can be formed on the surface of the negative current collector layer. Alternatively, the negative current collector layer can be formed by depositing or vapor-depositing the aforementioned metal onto a metal foil or substrate. Furthermore, when the negative current collector layer is composed of multiple metal foils, layers can be formed between these multiple metal foils.

[0164] 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. Alternatively, it can be less than 1 mm or less than 100 μm.

[0165] <Negative Electrode Active Material Layer>

[0166] The negative electrode active material layer is the electrode active material layer of this disclosure. The electrode active material layer of this disclosure can be referred to the above description.

[0167] <Solid Electrolyte Layer>

[0168] The solid electrolyte layer contains at least solid electrolyte particles and may optionally further contain adhesives, etc.

[0169] For solid electrolyte particles and binders, please refer to the above description.

[0170] There is no particular limitation on the thickness of the solid electrolyte layer, which can be, for example, greater than 0.1 μm and less than 1000 μm.

[0171] <Positive Electrode Active Material Layer>

[0172] The positive electrode active material layer contains at least a positive electrode active material, and may further contain solid electrolyte, conductive additives, binders, etc.

[0173] 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 include, for example, LiCoO2, LiMnO2, Li2NiMn3O8, LiVO2, LiCrO2, LiFePO4, LiCoPO4, LiNiO2, and LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc. In addition, a coating containing, for example, Li ion-conducting oxides such as LiNbO3 can be formed on the surface of these active materials.

[0174] There is no particular limitation on the content of positive electrode active material in the positive electrode active material layer.

[0175] For solid electrolytes, conductive additives, and adhesives, please refer to the above description.

[0176] 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.

[0177] <Positive current collector layer>

[0178] The positive current collector layer can be in the form of foil, plate, screen, perforated metal, foam, etc. The positive current collector layer can be a metal foil or a metal screen, and more specifically, it can be a metal foil. The positive current collector layer can be composed of multiple foils.

[0179] The metals constituting the positive current collector layer can be copper, nickel, chromium, gold, platinum, silver, aluminum, iron, titanium, zinc, cobalt, stainless steel, etc. In particular, the positive current collector layer may contain aluminum.

[0180] To adjust resistance, etc., a coating can be formed on the surface of the positive current collector layer. Alternatively, the positive current collector layer can be formed by depositing or vapor-depositing the aforementioned metal onto a metal foil or substrate. Furthermore, when the positive current collector layer is composed of multiple metal foils, layers can be formed between these multiple metal foils.

[0181] 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. Alternatively, it can be less than 1 mm or less than 100 μm.

[0182] <Other components>

[0183] The battery can be a battery in which the above-described components are housed within an outer casing. Regarding the outer casing, any known outer casing for the battery can be used. 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 obvious components such as terminals as required. The shape of the battery can be, for example, coin-shaped, stacked (bag-shaped), cylindrical, square, etc.

[0184] There are no particular limitations on the method of manufacturing the battery disclosed herein, such as including forming a negative electrode active material layer containing the electrode composite of the present disclosure.

[0185] As a method for forming a negative electrode active material layer containing an electrode composite, an example is a method of mixing constituent materials such as alloy-based electrode active material particles to obtain an electrode composite, and then dry-forming or wet-forming the obtained electrode composite.

[0186] The method for manufacturing a battery disclosed herein may further include sequentially stacking a negative electrode current collector layer, a negative electrode active material layer, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer to form an electrode stack.

[0187] Terminals and other components may be mounted on the electrode stack as needed. The battery is obtained by housing the electrode stack within a battery casing and sealing it.

[0188] Example

[0189] <<Example>>

[0190] <Preparation of Secondary Particles of Alloy-Based Electrode Active Materials>

[0191] Silicon primary particles are added to a solution containing a binder dissolved or dispersed in an organic solvent used as a dispersion medium to obtain a slurry. The organic solvent in the slurry is removed by spray drying to produce silicon electrode active material secondary particles, which are used as alloy-based electrode active materials.

[0192] The d50 particle size of the secondary particles of the obtained silicon electrode active material was determined using a laser diffraction / scattering particle size distribution measuring device (Partica LA-960V2, manufactured by HORIBA Co., Ltd.). The d50 particle size of the secondary particles of the silicon electrode active material was 9.4 μm.

[0193] <Fabrication of the Negative Electrode Active Material Layer>

[0194] (Providing the slurry)

[0195] The obtained silicon electrode active material secondary particles, binder, conductive additive, and solid electrolyte are added to an organic solvent to prepare a mixed solution. This mixed solution is then kneaded using an ultrasonic homogenizer to obtain a negative electrode composite slurry.

[0196] (Formation of the first preparatory negative electrode active material layer)

[0197] like Figure 1 As illustrated in (a), a first scraper with irregularities extending in the width direction of the electrode active material layer is used to apply the obtained negative electrode composite slurry onto a nickel foil serving as the negative electrode current collector layer. This forms a first preliminary negative electrode active material layer having multiple first thick film portions and multiple first thin film portions on the negative electrode current collector layer.

[0198] (Formation of the second preparatory negative electrode active material layer)

[0199] like Figure 1 As illustrated in (b), a second doctor blade with irregularities extending in the width direction of the electrode active material layer is used to apply the obtained negative electrode composite slurry onto a PET foil serving as a release sheet. This forms a second pre-formed negative electrode active material layer on the release sheet, having multiple second thick film portions and multiple second thin film portions.

[0200] (Layering of the first and second preparatory negative electrode active material layers)

[0201] like Figure 1 As illustrated in (c) and (d), the first thick film portion and the second thin film portion, as well as the first thin film portion and the second thick film portion, are respectively aligned, and the first and second pre-negative electrode active material layers are stacked, while the PET foil is peeled off. This yields a negative electrode laminate in which the negative electrode current collector layer and the negative electrode active material layer are stacked. The resulting negative electrode laminate is then shaped into a strip.

[0202] The thickness of the negative electrode active material layer, determined from cross-sectional SEM images taken using a scanning electron microscope (SEM), is 27.5 μm. Therefore, the ratio of the d50 particle size of the silicon electrode active material particles to the thickness of the negative electrode active material layer is 0.34.

[0203] <Fabrication of Solid Electrolyte Layer>

[0204] A binder and a solid electrolyte are added to an organic solvent to prepare a mixed solution. This mixed solution is then kneaded using an ultrasonic homogenizer to obtain a solid electrolyte composite slurry. The obtained solid electrolyte composite slurry is coated onto an aluminum (Al) foil used as a release sheet to create a solid electrolyte layer. Using the same steps, a total of three solid electrolyte layers are created and shaped into strips.

[0205] <Fabrication of the Positive Electrode Active Material Layer>

[0206] A binder, conductive additive, solid electrolyte, and LiNi as the positive electrode active material are added to an organic solvent. 0.8 Co 0.15 Mn 0.05 O2 is used to prepare a mixed solution. This mixed solution is then kneaded using an ultrasonic homogenizer to obtain a positive electrode composite slurry. The obtained positive electrode composite slurry is coated onto an Al foil serving as the positive electrode current collector layer to fabricate the positive electrode active material layer. This results in a positive electrode laminate consisting of the positive electrode current collector layer and the positive electrode active material layer, which is then shaped into a strip.

[0207] <Battery Making>

[0208] The negative electrode active material layer and the solid electrolyte layer are positioned opposite each other, and the negative electrode laminate is stacked with the first solid electrolyte layer, then pressed with a pressure roller at 25°C and 50 kN / cm. The solid electrolyte layer is transferred onto the negative electrode active material layer by peeling off the Al foil, which serves as a release sheet, from the solid electrolyte layer.

[0209] The positive electrode active material layer and the solid electrolyte layer are positioned opposite each other, and the positive electrode laminate is stacked with a second solid electrolyte layer. The laminations are then pressed together at 165°C using a pressure roller at 50 kN / cm. The solid electrolyte layer is transferred onto the positive electrode active material layer by peeling off the Al foil, which serves as a release liner, from the solid electrolyte layer.

[0210] The negative electrode laminate and the positive electrode laminate with the solid electrolyte layer transferred were respectively... 13.00mm, and A punching machine for cutting 11.28mm.

[0211] On the first solid electrolyte layer stacked on the negative electrode active material layer, a third solid electrolyte layer, punched to a specified size, is further transferred using a uniaxial press. The solid electrolyte layers on the negative electrode active material layer are then aligned with the solid electrolyte layers on the positive electrode active material layer, and the negative electrode stack and the positive electrode stack are then laminated.

[0212] An electrode sheet is removed by installing current into the positive and negative active material layers, and an Al laminate is sealed in using a vacuum laminator and constrained with a pressure of 5 MPa, thus producing an all-solid-state battery.

[0213] <<Comparative Examples>>

[0214] In the fabrication of the negative electrode active material layer, a non-protruding scraper is used to coat the negative electrode composite slurry onto the nickel foil that serves as the negative electrode current collector layer. The negative electrode active material layer is then formed on the negative electrode current collector layer in a manner that results in the same thickness as in the example. Otherwise, the negative electrode active material layer and the all-solid-state battery are obtained in the same manner as in the example.

[0215] <<Evaluation>>

[0216] <Area ratio of silicon electrode active material particles in each region>

[0217] Cross-sectional SEM images of the negative electrode active material layers of the examples and comparative examples were taken using a scanning electron microscope (SEM) with the measurement magnification set to 2000x. The width of these images was 2.3 times the thickness of the electrode active material layer.

[0218] In the cross-sectional SEM image, the ratio of the average particle size of the secondary particles of the silicon electrode active material to the thickness of the negative electrode active material layer is calculated. Furthermore, the average particle size of the secondary particles of the silicon electrode active material is the average particle size of five silicon electrode active material secondary particles extracted sequentially from the largest particle in the cross-sectional SEM image.

[0219] Within the entire image, the area ratio of secondary particles of the silicon electrode active material was calculated. The area ratios of secondary particles of the silicon electrode active material in the examples and comparative examples were 0.51 and 0.53, respectively.

[0220] The image was hypothetically divided into 12 equal parts along the width of the negative electrode active material layer, creating distinct regions. The cross-sectional SEM image was analyzed using Image-J (Ver. 1.54f) image processing software to calculate the area ratio of silicon electrode active material particles in each of the 12 distinct regions. Based on these area ratios, the difference between the maximum and minimum values ​​of the aforementioned area ratios, the interquartile range, and the dispersion were calculated between each distinct region. The maximum values ​​in the examples and comparative examples were 0.69 and 0.79, respectively. Figure 2 The histogram showing these area proportions is shown in the image.

[0221] <Increase in constraint pressure>

[0222] For the obtained all-solid-state battery, a weighing sensor was used to measure the increase in confinement pressure when charging from an uncharged state to 4.05V. This method was used to measure the increase in confinement pressure a total of three times. The increase in confinement pressure represents the expansion of secondary particles in the silicon electrode active material.

[0223] The evaluation results for each case are shown in Table 1, and Figure 2 and 3 .

[0224] [Table 1]

[0225]

[0226] As shown in Table 1, in the negative electrode active material layer of the embodiment, the difference between the maximum and minimum values ​​of the area ratio of silicon electrode active material particles among the 12 distinct regions, the interquartile range, the dispersion, and the value of the area ratio of silicon electrode active material particles in the entire cross-sectional SEM image / the maximum value of the area ratio of silicon electrode active material particles in each distinct region of the cross-sectional SEM image are all within the range of this disclosure.

[0227] like Figure 2 As shown, in the negative electrode active material layer of the embodiment, the frequency distribution of the area ratio of silicon electrode active material particles in each of the 12 distinct regions is relatively narrow.

[0228] As shown in Table 1 and Figure 3 As shown, although the d50 particle size / thickness value of the embodiment is larger than that of the comparative example, the increase in constraint pressure of the battery in the embodiment is smaller than that of the battery in the comparative example.

[0229] The above results confirm that in the negative electrode active material layer of the embodiment manufactured using the method of this disclosure, the silicon electrode active material particles are present relatively uniformly in the width direction. As a result, the increase in confinement pressure is small in the battery of the embodiment.

[0230] It should be noted that in this embodiment, an example is shown where the electrode active material layer manufactured using the method of this disclosure is a negative electrode active material layer, but the electrode active material layer can be a positive electrode active material layer.

Claims

1. A method for manufacturing an electrode active material layer, comprising the following steps: Provides an electrode slurry comprising alloy-based electrode active material particles and a dispersion medium, wherein, The ratio of the d50 particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer is 0.10 to 0.

50. Using a first scraper with concave and convex shapes extending in the width direction of the electrode active material layer, the electrode composite slurry is coated onto a first substrate, thereby forming a first pre-electrode active material layer having a plurality of first thick film portions and a plurality of first thin film portions on the first substrate. Using a second scraper with concave and convex shapes extending in the width direction of the electrode active material layer, the electrode composite slurry is coated onto a second substrate, thereby forming a second pre-electrode active material layer having a plurality of second thick film portions and a plurality of second thin film portions on the second substrate. and The first thick film portion and the second thin film portion, as well as the first thin film portion and the second thick film portion, are respectively positioned opposite each other, and the first pre-electrode active material layer and the second pre-electrode active material layer are stacked.

2. The method according to claim 1, wherein, The d50 particle size of the alloy-based electrode active material particles is 5μm to 15μm, and the thickness of the electrode active material layer is 10μm to 100μm.

3. The electrode active material layer is a layer containing alloy-based electrode active material particles. in, In the cross-sectional SEM image, the ratio of the average particle size of the alloy-based electrode active material particles to the thickness of the electrode active material layer is 0.20 to 1.

0. The average particle size of the alloy-based electrode active material particles is the average particle size of at least five alloy-based electrode active material particles extracted sequentially from the largest particles in the cross-sectional SEM image. Furthermore, the cross-sectional SEM image is an image of the electrode active material layer with a width 2.3 times the thickness of the electrode active material layer. In the cross-sectional SEM image, the difference between the maximum and minimum area ratios of the alloy-based electrode active material particles in the 12 hypothetically divided regions along the width direction of the electrode active material layer is less than 0.

40.

4. The electrode active material layer according to claim 3, wherein, The difference is less than 0.

25.

5. The electrode active material layer according to claim 3, wherein, In the SEM image of the cross section, the interquartile range of the area ratio of the active material particles of the alloy electrode is below 0.15 in each distinct region.

6. The electrode active material layer according to claim 3, wherein, In the SEM image of the cross section, the area ratio of the active material particles of the alloy electrode is less than 0.015 between the different regions.

7. The electrode active material layer according to claim 3, wherein, The maximum value of the ratio of the area ratio of the active material particles of the alloy electrode in the entire cross-sectional SEM image to the area ratio of the active material particles of the alloy electrode in each distinct region of the cross-sectional SEM image is 0.70 or higher.

8. The electrode active material layer according to claim 3, wherein, The active material particles of the alloy-based electrode are silicon electrode active material particles.

9. The electrode active material layer according to claim 3, wherein, The alloy-based electrode active material particles are secondary particles containing multiple primary electrode active material particles.

10. The electrode active material layer according to claim 9, wherein, The secondary particles also contain an adhesive.

11. A battery comprising an electrode active material layer according to any one of claims 3 to 10.

12. The battery according to claim 11, wherein it is a solid-state battery.

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