Method for manufacturing all-solid-state battery

Abstract

To provide a method for manufacturing an all-solid-state battery in which a Si-based negative electrode active material is not limited to specific fine particles, and volume expansion of the Si-based negative electrode active material can be suppressed.SOLUTION: A method for manufacturing an all-solid-state battery of the present disclosure includes the steps of: (a) kneading a negative electrode active material 10 containing Si, thermosetting resin 20 as a binder, and a conductive material 30 to obtain a kneaded material; (b) applying the kneaded material to a surface of a negative electrode current collector 40 to form a kneaded material layer 50; (c) applying solid electrolyte slurry 60 on a surface of the kneaded material layer 50 and impregnating the solid electrolyte slurry 60 into the kneaded material layer 50 to form a negative electrode active material layer 70; and (d) drying the negative electrode active material layer 70.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing an all-solid-state battery. In particular, the present disclosure relates to a method for manufacturing an all-solid-state battery using an Si-based negative electrode active material.

Background Art

[0002] In the field of lithium-ion batteries, carbon-based negative electrode active materials have conventionally been used. However, in recent years, Si-based negative electrode active materials have been increasingly used in order to improve the energy density.

[0003] However, compared with carbon-based negative electrode active materials, Si-based negative electrode active materials have a large volume expansion during charging. As a result, various problems have occurred, and several attempts have been proposed to solve these problems.

[0004] For example, Patent Document 1 discloses a lithium-ion secondary battery in which, in addition to an Si-based negative electrode active material, a negative electrode active material containing a negative electrode active material having further strong magnetism is used, and a hard magnetic body is disposed outside a power generation element. Patent Document 1 also discloses that even if the Si-based negative electrode active material layer is pulverized due to volume expansion, dissipation is suppressed by the attraction between the fine particles.

[0005] Patent Document 2 discloses a negative electrode for a sulfide all-solid-state battery, which includes a plurality of Si-based material layers containing an Si-based material and a plurality of void layers, and a laminated portion in which these Si-based material layers and void layers are alternately laminated. Patent Document 2 also discloses that the void layer absorbs the volume expansion of the Si material layer due to the alternating lamination of the Si-based material layer and the void layer.

[0006] Patent Document 3 discloses that a Si-based negative electrode active material composed of a Si-Sn-Fe-Cu alloy and having an average particle diameter of 1 to 10 μm is bound with a polyimide binder. And Patent Document 3 discloses that, by using fine particles having an average particle diameter of 1 to 10 μm as the Si-based negative electrode active material, the contact area between the particles of the Si-based negative electrode active material and the binder is increased, and the binding force is increased.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] The attempt of Patent Document 1 does not suppress the volume expansion of the Si-based negative electrode active material layer. Even if the Si-based negative electrode active material layer expands in volume and the Si-based negative electrode active material layer is destroyed, it compensates so as not to impair the function of the battery. Also, the attempt of Patent Document 2 does not suppress the volume expansion of the Si-based negative electrode active material layer (Si material layer), but absorbs the volume expansion. However, it is desired to suppress the volume expansion of the Si-based negative electrode active material layer. The attempt of Patent Document 3 can be expected to suppress the volume expansion of the Si-based negative electrode active material layer by increasing the binding force, but there is a problem that the Si-based negative electrode active material is limited to fine particles.

[0009] From these facts, the inventor has found the problem that, regarding all-solid-state batteries, it is expected that the Si-based negative electrode active material is not limited to specific fine particles and the volume expansion of the Si-based negative electrode active material is suppressed.

[0010] The present disclosure has been made to solve the above problems. That is, an object of the present disclosure is to provide a method for manufacturing an all-solid-state battery in which the Si-based negative electrode active material is not limited to specific fine particles and the volume expansion of the Si-based negative electrode active material can be suppressed.

Means for Solving the Problems

[0011] The inventors of the present invention have conducted intensive studies to achieve the above object and completed a method for manufacturing an all-solid-state battery of the present disclosure. The method for manufacturing an all-solid-state battery of the present disclosure includes the following aspects. A method for manufacturing an all-solid-state battery including the following steps (a) to (d): (a) A step of kneading a negative electrode active material containing Si, a thermosetting resin as a binder, and a conductive material to obtain a kneaded product. (b) A step of applying the kneaded product to the surface of a negative electrode current collector to form a kneaded product layer. (c) A step of applying a solid electrolyte slurry to the surface of the kneaded product layer and impregnating the inside of the kneaded product layer with the solid electrolyte slurry to form a negative electrode active material layer, and (d) A step of drying the negative electrode active material layer.

Effects of the Invention

[0012] According to the present disclosure, by using a thermosetting resin as a binder, forming a kneaded product layer containing the thermosetting resin on the surface of a negative electrode current collector in advance, and impregnating the inside of the kneaded product layer with a solid electrolyte slurry, a strong negative electrode active material layer can be obtained. As a result, it is possible to provide a method for manufacturing an all-solid-state battery in which the Si-based negative electrode active material is not limited to specific fine particles and the volume expansion of the Si-based negative electrode active material can be suppressed.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

[0014] Hereinafter, embodiments of a method for manufacturing an all-solid-state battery of the present disclosure will be described in detail. Note that the embodiments shown below do not limit the method for manufacturing an all-solid-state battery of the present disclosure.

[0015] Although not bound by theory, the reason why the method for manufacturing an all-solid-state battery of the present disclosure can suppress the volume expansion of the Si-based negative electrode active material will be described with reference to the drawings.

[0016] FIG. 1 is an explanatory diagram schematically showing a state in which a kneaded material of a negative electrode active material containing Si, a thermosetting resin as a binder, and a conductive material is applied to the surface of a negative electrode current collector to form a kneaded material layer. FIG. 2 is an explanatory diagram showing the state immediately after applying a solid electrolyte slurry to the surface of the kneaded material layer of FIG. 1. FIG. 3 is an explanatory diagram showing the state in which the negative electrode active material layer is formed by impregnating the inside of the kneaded material layer with a solid electrolyte slurry.

[0017] When forming the negative electrode active material layer, conventionally, all the substances constituting the negative electrode active material layer were kneaded and then applied to the negative electrode current collector. Then, when the negative electrode active material layer thus formed was dried and fired and mounted on the all-solid-state battery, when a thermoplastic resin was used as the binder, the volume expansion of the negative electrode active material layer during charging was large.

[0018] In contrast, in the method for manufacturing a solid electrolyte of the present disclosure, a thermosetting resin is selected as a binder, and a kneaded product of substances other than the solid electrolyte among the substances constituting the negative electrode electrolyte layer is applied to the surface of the negative electrode current collector to form a kneaded product layer in advance. As shown in FIG. 1, the kneaded product layer 50 contains a negative electrode active material 10, a thermosetting resin 20, and a conductive material 30. The negative electrode active material 10 is typically Si. Then, a solid electrolyte slurry 60 is applied to the kneaded product layer 50 (see FIG. 2), and this is impregnated to form a negative electrode active material layer 70 (see FIG. 3). The present inventors have found that in a all-solid-state battery in which the thus formed negative electrode active material layer 70 is dried, fired, and mounted, the volume expansion of the negative electrode active material during charging is suppressed.

[0019] Although not bound by theory, this is because when a thermosetting resin is used, Plastic compared with the case where a thermosetting resin is used, the mechanical strength of the negative electrode active material layer after drying and firing is improved, which contributes to the suppression of the volume expansion of the negative electrode active material layer after drying and firing. Note that the thermosetting resin is cured by heat during drying and / or firing, and the mechanical strength is improved.

[0020] Also, in the case of a sulfide-based all-solid-state battery, conventionally, when a thermosetting resin is used as a binder, the solvent of the thermosetting resin may react with the solid electrolyte, making charging impossible. However, when a solid electrolyte slurry is separately impregnated inside the kneaded product layer containing the thermosetting resin as in the method for manufacturing an all-solid-state battery of the present disclosure, the reaction between the solvent of the thermosetting resin and the solid electrolyte can be suppressed. That is, as shown in FIG. 1, by devising the manufacturing method of applying a kneaded product other than the solid electrolyte to the surface of the negative electrode current collector to form a kneaded product layer in advance, a thermosetting resin with high mechanical strength after firing can be used as a binder. As a result, the negative electrode active material layer after firing can be strengthened, and even a Si-based negative electrode active material layer can suppress its volume expansion.

[0021] Next, the constituent requirements of the manufacturing method of the all-solid-state battery according to the present disclosure, which have been completed based on the findings described so far, will be described.

[0022] "Method for Manufacturing All-Solid-State Battery" The method for manufacturing an all-solid-state battery of the present disclosure includes a kneaded product preparation step (step (a)), a kneaded product layer formation step (step (b)), a negative electrode active material layer formation step (step (c)), and a negative electrode active material layer drying step (step (d)). Hereinafter, each step will be described.

[0023] 〈Kneaded Product Preparation Step〉 In the kneaded product preparation step (step (a)), a negative electrode active material containing Si, a thermosetting resin as a binder, and a conductive material are kneaded to obtain a kneaded product.

[0024] As long as the negative electrode active material containing Si, the thermosetting resin as a binder, and the conductive material can be uniformly kneaded, there is no particular limitation on the kneading method. For example, a method of stirring with an ultrasonic dispersing device, a method using a batch-type agitator mixer, and a method using a continuous extrusion kneader having paddles can be mentioned. From the viewpoint of uniform kneading, a method of stirring with an ultrasonic dispersing device is preferable.

[0025] Typical examples of the negative electrode active material containing Si include one or more substances selected from the group consisting of elemental Si and Si alloys. The Si alloy is not particularly limited as long as it is an alloy of Si and a metal capable of forming an alloy with Si. Examples of the Si alloy include Si-Al-based alloys, Si-Sn-based alloys, Si-In-based alloys, Si-Ag-based alloys, Si-Pb-based alloys, Si-Sb-based alloys, Si-Bi-based alloys, Si-Mg-based alloys, Si-Ca-based alloys, Si-Ge-based alloys, Si-Pb-based alloys, and Si-Cu-based alloys. For example, the Si-Al-based alloy may be an alloy composed of Si, Al, and inevitable impurities, or an alloy containing at least Si and Al and further containing another element and inevitable impurities. The same applies to alloys other than the Si-Al-based alloy.

[0026] As the negative electrode active material containing Si, elemental Si is preferred because of its high energy density. Of course, the negative electrode active material containing elemental Si may contain inevitable impurities. In the present specification, the inevitable impurities refer to impurities that cannot be avoided in the production of raw materials, etc., or impurities that cause a significant increase in production costs to avoid their inclusion.

[0027] The thermosetting resin is not particularly limited as long as it has the function of a binder. Examples of such thermosetting resins include polyimide (PI), silicone resin (SI), phenolic resin (PF), epoxy resin (EP), melamine resin (MF), urea resin (UF), unsaturated polyester resin (UP), polyurethane (PUR), etc. A solvent is often used during kneading. In the case of polyimide (PI), N-methyl-2-pyrrolidone (NMP) can be used as the solvent. When a sulfide-based solid electrolyte is selected as the solid electrolyte, N-methyl-2-pyrrolidone (NMP) and the sulfide-based solid electrolyte react very easily. As described above, in the method for manufacturing an all-solid-state battery of the present disclosure, a kneaded product other than the solid electrolyte is applied to the surface of the negative electrode current collector to form a kneaded product layer in advance, and separately, the kneaded product layer is impregnated with the solid electrolyte. Therefore, the method for manufacturing an all-solid-state battery of the present disclosure is less affected by the solvent. Therefore, when a sulfide-based solid electrolyte is selected as the solid electrolyte and polyimide (PI) is selected as the binder, the method for manufacturing an all-solid-state battery of the present disclosure is particularly suitable for suppressing the reaction between the solid electrolyte and the solvent (N-methyl-2-pyrrolidone (NMP)).

[0028] The conductive material can be selected from carbon materials, for example, VGCF (vapor-grown carbon fiber), acetylene black, ketjen black, or carbon nanotubes, etc., or a combination thereof. VGCF is fibrous and is preferred because it contributes to the improvement of the strength of the negative electrode active material layer after firing.

[0029] <Kneaded Product Layer Formation Step> In the kneaded product layer formation step (step (b)), the kneaded product obtained in step (a) is applied to the surface of the negative electrode current collector to form a kneaded product layer.

[0030] If the kneaded product can be uniformly applied, there is no particular limitation on the application method. Examples of the application method include the blade method using an applicator. In addition, the application of the kneaded product includes drying and removing the solvent. Examples of the drying method include natural drying and heating and drying at 100 to 170 °C, but are not limited thereto.

[0031] As the negative electrode current collector, for example, Ag, Cu, Au, Al, Ni, Fe, stainless steel, or Ti, etc., or alloys thereof can be used as the material of the negative electrode current collector layer. From the viewpoint of chemical stability, Cu and Ni are preferable, and when a sulfide-based solid electrolyte is used, Ni is particularly preferable from the viewpoint of avoiding sulfidation of the negative electrode current collector.

[0032] 〈Negative electrode active material layer formation step〉 In the negative electrode active material formation step (step (c)), a solid electrolyte slurry is applied to the surface of the kneaded product layer formed in step (b), and the solid electrolyte is impregnated into the kneaded product layer to form a negative electrode active material layer.

[0033] If it does not adversely affect the kneaded product layer and the solid electrolyte slurry can be uniformly applied, there is no particular limitation on the application method. Examples of the application method include the blade method using an applicator and the screen printing method. From the viewpoint of accurately applying the solid electrolyte slurry to a predetermined thickness, the screen printing method is preferable.

[0034] The solid electrolyte slurry applied to the surface of the kneaded product layer (see Figure 2) spontaneously impregnates into the kneaded product layer (see Figure 3). However, it is preferable to expose it to a vacuum in the state shown in Figure 2 at least during or after the application of the solid electrolyte slurry to promote the impregnation of the solid electrolyte slurry into the kneaded product layer.

[0035] As the solid electrolyte, sulfide-based amorphous solid electrolytes such as Li2S-P2S5, Li2O·Li2S·P2S5, Li2S, P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, etc.; or oxide-based amorphous solid electrolytes such as Li2O-B2O3-P2O 5、 Li2O-SiO2, etc.; or oxide-based crystalline solid electrolytes such as LiI, Li3N, Li5La3Ta2O 12 、Li7Zr2O 12 、Li6BaLa2Ta2O 12 、Li3PO (4-3 / 2w) N w (w<1), etc.; or sulfide-based crystalline solid electrolytes such as Li7P3S 11 、Li 3.25 P 0.75 S4 and other glass ceramics, or Li 3.24 P 0.24 Ge 0.76 S4 and other thio-LiSiO-based crystals, those having an argyrodite-type crystal structure such as Li6PS5X (X = Cl, Br) (hereinafter sometimes referred to as "argyrodite-type sulfide solid electrolyte"), etc.; or they can be selected from combinations thereof. From the viewpoints of high lithium ion conductivity and electrochemical stability, the argyrodite-type sulfide solid electrolyte is preferred.

[0036] A solvent is added to the above-described solid electrolyte to obtain a solid electrolyte slurry. As the solvent, a substance that does not deteriorate the kneaded layer and the solid electrolyte may be appropriately selected.

[0037] 〈Negative electrode active material layer drying process〉 In the negative electrode active material layer drying process (process (d)), the negative electrode active material layer formed in process (c) is dried. Examples of the drying method include natural drying and heating drying at 100 to 170°C, but are not limited thereto. The thermosetting resin may be cured by this drying, or for example, the thermosetting resin may be cured by firing in a process described later. Examples of the process described later include, for example, after drying the negative electrode active material layer, further roll pressing and then firing, or laminating single cells and roll pressing and then firing.

[0038] 〈Manufacture of Battery〉 In the processes (a) to (d) described so far, the negative electrode (negative electrode current collector and negative electrode active material layer) can be formed. In addition, a separator (solid electrolyte layer) and a positive electrode (positive electrode current collector and positive electrode active material layer) are formed. Then, the negative electrode, the separator, and the positive electrode are stacked in this order, that is, the negative electrode current collector, the negative electrode active material layer, the separator (solid electrolyte layer), the positive electrode active material layer, and the positive electrode current collector are stacked in this order to form a single cell. Further, single cells are stacked to manufacture a battery.

[0039] For the formation of the separator (solid electrolyte layer) and the positive electrode (positive electrode current collector and positive electrode active material layer), and the manufacture of the single cell, well-known methods for all-solid-state batteries can be adopted. Hereinafter, the formation of the separator (solid electrolyte layer), the positive electrode (positive electrode current collector and positive electrode active material layer), and the single cell, and the stacking of the single cells will be outlined, but are not limited thereto.

[0040] 〈Formation of Separator〉 The separator (solid electrolyte layer) contains at least a solid electrolyte, and may contain a binder or the like as necessary. For the solid electrolyte, reference can be made to the content described in "〈Negative Electrode Active Material Layer Formation Process〉". As the binder, a polymer resin such as polyvinylidene fluoride (PVDF), butadiene rubber (BR), or styrene-butadiene rubber (SBR), or a combination thereof can be selected.

[0041] The method for forming the separator (solid electrolyte layer) is not particularly limited. For example, there may be mentioned a method of compression molding powder or pellets of a raw material for the separator (solid electrolyte layer) containing at least a solid electrolyte, or the like. Alternatively, there may be mentioned a method of applying a raw material slurry for the separator (solid electrolyte layer) containing at least a solid electrolyte and a solvent onto the surface of a support and drying it, or the like.

[0042] 〈Formation of the positive electrode〉 In the positive electrode (positive electrode current collector and positive electrode active material layer), a positive electrode active material layer is formed on the surface of the positive electrode current collector. As the positive electrode current collector, reference can be made to the negative electrode current collector described in the "〈Step of forming the kneaded product layer〉". Among them, from the viewpoint of chemical stability, aluminum is preferable as the positive electrode current collector. The positive electrode active material layer contains a positive electrode active material, and optionally a conductive material, a binder, and a solid electrolyte. As the positive electrode active material, there can be selected a metal oxide containing at least one transition metal selected from manganese, cobalt, nickel, and titanium and lithium, for example, lithium cobaltate, lithium nickelate, lithium manganate, or lithium nickel cobalt manganate, etc., a hetero-element substituted Li-Mn spinel, lithium titanate, lithium metal phosphate, or a combination thereof. Regarding the conductive material, reference can be made to the content described in the "〈Step of preparing the kneaded product〉". Regarding the solid electrolyte, reference can be made to the content described in the "〈Step of forming the negative electrode active material layer〉". Also, as the binder, a polymer resin, for example, polyvinylidene fluoride (PVDF), butadiene rubber (BR), or styrene butadiene rubber (SBR), etc., or a combination thereof can be selected.

[0043] The method for forming the positive electrode (positive electrode current collector and positive electrode active material layer) is not particularly limited. For example, there may be mentioned a method of applying a raw material slurry for the positive electrode active material containing at least a positive electrode active material onto the surface of the positive electrode current collector and drying it, or the like.

[0044] 〈Formation of the single cell〉 A single cell is formed by laminating a negative electrode current collector, a negative electrode active material layer, a separator (solid electrolyte layer), a positive electrode active material layer, and a positive electrode current collector in this order. There is no particular limitation on the lamination method. For example, the separator (solid electrolyte layer) is formed on the surface of a support, and one of the negative electrode active material layer and the positive electrode active material layer is bonded to the separator side (solid electrolyte layer side) and pressed. Then, the support of the separator is peeled off, and the other of the negative electrode active material layer and the positive electrode active material layer is bonded to the separator surface (the surface of the solid electrolyte layer), and pressed again. A roll press may be used for pressing.

[0045] 〈Lamination of Single Cell〉 Furthermore, single cells are laminated and then fired at 200 to 300 °C. When laminating single cells, the positive electrode current collector and the negative electrode current collector are not attached to each single cell, and the positive electrode current collector and the negative electrode current collector are attached to both ends of the lamination.

Example

[0046] Hereinafter, the manufacturing method of the all-solid-state battery of the present disclosure will be described more specifically by way of examples and comparative examples. Note that the manufacturing method of the all-solid-state battery of the present disclosure is not limited to the conditions used in the following examples.

[0047] 《Preparation of Battery Sample》 A battery sample was prepared in the following manner.

[0048] 〈Example 1〉 · Preparation of Positive Electrode Active Material Using a rolling fluidized coating device (manufactured by Paurek Co., Ltd.), lithium niobate was coated on positive electrode active material particles (particles having Li 1.15 Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2 as the main phase) in an air atmosphere, and this was fired in an air atmosphere. Thereby, positive electrode active material particles having a coating layer of lithium niobate were obtained.

[0049] · Preparation of Positive Electrode A polypropylene container was filled with PVdF, the above-mentioned positive electrode active material particles, an alluaudite-type solid electrolyte, and VGCF (registered trademark, manufactured by Showa Denko K.K.), and stirred for 30 seconds with an ultrasonic disperser (UH-50 manufactured by SMT Co., Ltd.). Next, the container was shaken for 3 minutes with a shaker (TTM-1 manufactured by Shibata Scientific Technology Ltd.), and further stirred for 30 seconds with the ultrasonic disperser. After shaking for 3 minutes with the shaker, this was applied onto an aluminum foil to a width of 72 mm. At that time, it was applied by the blade method using an applicator. Also, each raw material was adjusted so that the electronic conductivity of the positive electrode was 20 mS / cm and the ionic conductivity was 0.1 mS / cm. After application, it was air-dried, and further dried on a hot plate at 100 °C for 30 minutes to obtain a positive electrode having a positive electrode active material layer formed on an aluminum foil (positive electrode current collector). At that time, the film thickness was measured with a rotary caliper, and it was confirmed that the sag amount was 1 mm.

[0050] · Preparation of negative electrode A polypropylene container was filled with NMP, polyamic acid, negative electrode active material particles (Si particles), VGCF, and hexamethylcyclotrisiloxane (particle size 100 μm), and stirred for 30 minutes with an ultrasonic disperser. Then, this was applied onto a Ni foil. At that time, it was applied by the blade method using an applicator. After that, it was air-dried and dried on a hot plate at 150 °C for 30 minutes. Also, an alluaudite-type solid electrolyte slurry having an average particle size of 0.5 μm was filled using a screen printing machine to obtain a negative electrode.

[0051] · Separator (solid electrolyte layer) A polypropylene container was filled with heptane, butadiene rubber (BR), and a sulfide solid electrolyte, and stirred with an ultrasonic disperser for 30 seconds. Next, the container was shaken with a shaker for 30 minutes, and further stirred with the ultrasonic disperser for 30 seconds. After shaking with the shaker for 3 minutes, it was applied onto an aluminum foil. At that time, it was applied by the blade method using an applicator. Then, it was air-dried and dried on a hot plate at 100 °C for 30 minutes to form a solid electrolyte layer on the aluminum foil as a substrate.

[0052] · Formation of single cell The negative electrode active material layer of the negative electrode and the solid electrolyte layer were bonded so as to be in direct contact, pressed at a pressure of 1.6 t / cm, and then the aluminum foil as the substrate was peeled off. Subsequently, the positive electrode active material layer of the positive electrode and the solid electrolyte layer were bonded so as to be in direct contact and pressed at a pressure of 1.6 t / cm. Then, the aluminum foil as the positive electrode current collector was peeled off, and pressed at a pressure of 5 t / cm and 185 °C to be densified. Then, it was fired at 250 °C.

[0053] · Attachment of current collector foil Using butadiene rubber (BR), carbon-coated foils were attached to both sides of the single cell in alignment with the positive electrode end.

[0054] · Lamination of single cells Ten sets of the above single cells were laminated, and the terminals were welded to form a laminated cell.

[0055] 〈Comparative Example 1〉 In the preparation of the negative electrode, a battery sample was prepared in the same manner as in Example 1, except that PVDF was used as a binder.

[0056] 〈Comparative Example 2〉 In the preparation of the negative electrode, a battery sample was prepared in the same manner as in Example 1, except that a kneaded product including a solid electrolyte was prepared. That is, a battery sample was prepared in the same manner as in Example 1, except that a kneaded product of NMP, polyamic acid, negative electrode active material particles (Si particles), VGCF, hexamethylcyclotrisiloxane (particle size 100 μm), and an alligatorite-type solid electrolyte was applied onto a Ni foil to form a negative electrode active material layer.

[0057] 《Evaluation》 Charge and discharge were performed at 0.1C (0.01C cut) with CCCV charge and discharge of 4.05V - 2.5V, and the amount of expansion of the negative electrode active material layer in the second cycle was measured. The amount of expansion was measured with the state of charge (SOC) being 0 - 100%. The results are shown in Table 1.

[0058]

Table 1

[0059] From Table 1, it can be understood that in Example 1 where a kneaded product layer containing a thermosetting resin was previously formed on the surface of the negative electrode current collector and the inside of the kneaded product layer was separately impregnated with a solid electrolyte slurry, volume expansion was suppressed. In contrast, in Comparative Example 1 where a kneaded product layer containing a thermoplastic resin was previously formed on the surface of the negative electrode current collector and the inside of the kneaded product layer was separately impregnated with a solid electrolyte slurry, it can be understood that the volume expansion became large. Also, in Comparative Example 2 where a thermosetting resin, a negative electrode active material, and an alligatorite-type solid electrolyte were kneaded simultaneously, charging could not be performed. This is presumably because the alligatorite-type solid electrolyte is a sulfide-based solid electrolyte and the alligatorite-type solid electrolyte reacted with the solvent (NMP) of the thermosetting resin.

[0060] From the above results, the effect of the manufacturing method of the all-solid-state battery of the present disclosure could be confirmed.

Description of Reference Numerals

[0061] 10 Negative electrode active material 20 Thermosetting resin 30 Conductive material 40 Negative electrode current collector 50 Kneaded product layer 60 Solid electrolyte slurry 70 Negative electrode active material layer

Claims

【Claim 1】 comprising the following steps (a) to (d): (a) kneading a negative electrode active material containing Si, a thermosetting resin as a binder, a conductive material, and a solvent to obtain a kneaded product; (b) applying the kneaded product onto the surface of a negative electrode current collector to form a kneaded product layer; (c) applying a slurry containing a sulfide-based solid electrolyte (however, excluding the case where the slurry contains a solid electrolyte dissolved in a solvent and insoluble fine particles) onto the surface of the kneaded product layer, impregnating the slurry into the interior of the kneaded product layer to form a negative electrode active material layer; and (d) drying the negative electrode active material layer; wherein the binder is polyimide; the solvent is N-methyl-2-pyrrolidone; and the sulfide-based solid electrolyte is a sulfide-based amorphous solid electrolyte selected from Li₂S-P₂S₅, Li₂O·Li₂S·P₂S₅, Li₂S, P₂S₅, Li₂S-SiS₂, LiI-Li₂S-SiS₂, LiI-Li₂S-P₂S₅, LiI-Li₂S-P₂O₅, or LiI-Li₃PO₄-P₂S₅; a sulfide-based crystalline solid electrolyte selected from glass ceramics, thio-LiSiO-based crystals, or argyrodite-type sulfide solid electrolytes; or a combination thereof and is a method for manufacturing an all-solid-state battery.

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