Method for manufacturing solid-state battery

Abstract

Provided is a method for manufacturing a solid-state battery, the size of which is easy to control. This method for manufacturing a solid-state battery (1) is provided with: a negative-electrode-side sheet member forming step (S40) in which a negative-electrode-side sheet member (400) is formed; a positive electrode-side sheet member forming step (S30) in which a positive electrode-side sheet member (300) is formed; and an integrated pressing step (S9) in which the negative electrode-side sheet member (400) and the positive electrode-side sheet member (300) are laminated and integrated. Furthermore, the negative electrode-side sheet member forming step (S40) comprises: a negative electrode-side solid electrolyte layer transfer step (S6) in which a negative electrode-side solid electrolyte layer (SE3) is pressed and transferred on at least the negative electrode current collector foil (221); and a negative electrode-side sheet member cutting step (S7) in which the sheet-like member obtained by transfer is cut. The positive electrode-side sheet member forming step (S30) has a positive electrode pressing step (S3) in which a first solid electrolyte layer (SE1) is provided on a surface of the positive electrode-side sheet member (300) facing the negative electrode-side solid electrolyte layer (SE3), and the negative electrode-side solid electrolyte layer (SE3) has a smaller binder content than the first solid electrolyte layer (SE1).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a solid battery. Background Art

[0002] In recent years, research and development related to secondary batteries that contribute to energy efficiency have been conducted in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy.

[0003] As a method for automatically manufacturing secondary batteries with high productivity, there is known a method in which materials such as a positive electrode layer and a negative electrode layer are pulled out by rollers and the stacked materials are cut.

[0004] [Prior Art Literature]

[0005] (Patent Document)

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 1999-288733 Summary of the Invention

[0007] [Problems to be solved by the invention]

[0008] In the case of manufacturing a secondary battery having a plurality of layers including a solid electrolyte layer, a method for manufacturing a solid battery that can easily control size is required.

[0009] [Technical means to solve the problem]

[0010] (1) The present invention relates to a method for manufacturing a solid battery (e.g., solid battery 1), comprising: a negative electrode side sheet component forming step (e.g., negative electrode side sheet component forming step S40), forming a negative electrode side sheet component (e.g., negative electrode side sheet component 400) including at least a negative electrode current collector (e.g., negative electrode current collector foil 221) and a negative electrode side solid electrolyte layer (e.g., negative electrode side solid electrolyte layer SE3); a positive electrode side sheet component forming step (e.g., positive electrode side sheet component forming step S30), forming a positive electrode side sheet component (e.g., positive electrode side sheet component 300) including at least a positive electrode current collector (e.g., positive electrode current collector foil 321) and a positive electrode active material layer (e.g., positive electrode active material layer 31); and an integration step (e.g., integration pressing step S9), stacking and integrating the negative electrode side sheet component and the positive electrode side sheet component; and, The aforementioned negative electrode side sheet component forming process includes: a negative electrode side solid electrolyte layer transfer process (for example, a negative electrode side solid electrolyte layer transfer process S6), in which the aforementioned negative electrode side solid electrolyte layer is transferred by pressing at least on the aforementioned negative electrode collector; and a negative electrode side sheet component cutting process (for example, a negative electrode side sheet component cutting process S7), in which the sheet-shaped component obtained by transfer is cut; the aforementioned positive electrode side sheet component forming process includes: a positive electrode pressing process (for example, a positive electrode pressing process S3), in which at least the positive electrode collector and the positive electrode active material layer are pressed; before the aforementioned integration process, a first solid electrolyte layer (for example, a first solid electrolyte layer SE1) is provided on the surface of the aforementioned positive electrode side sheet component opposite to the aforementioned negative electrode side solid electrolyte layer, and the aforementioned negative electrode side solid electrolyte layer has a lower binder content than the aforementioned first solid electrolyte layer.

[0011] (2) It is preferable that the maximum value of the pressing pressure in the positive electrode pressing step is at least equal to or greater than the maximum value of the pressing pressure in the negative electrode side solid electrolyte layer transfer step.

[0012] (3) It is preferable that the positive electrode side sheet member is pressed twice or more.

[0013] (4) It is preferable that the thickness of the positive electrode side sheet member in the stacking direction is larger than that of the negative electrode side sheet member.

[0014] (5) Preferably, before the aforementioned integration process, a second solid electrolyte layer transfer process (for example, a second solid electrolyte layer transfer process S4) is performed, wherein a second solid electrolyte layer (for example, a second solid electrolyte layer SE2) is stacked and transferred between the aforementioned negative electrode side solid electrolyte layer and the aforementioned first solid electrolyte layer, and the second solid electrolyte layer contains a higher content of the aforementioned binder than the aforementioned negative electrode side solid electrolyte layer.

[0015] (6) Preferably, the negative electrode side sheet member includes a negative electrode active material layer (eg, the negative electrode active material layer 21 ).

[0016] (7) It is preferable to include an intermediate layer transfer step (for example, intermediate layer transfer step S5 ) in which an intermediate layer (for example, intermediate layer 5 ) is stacked and transferred on the negative electrode layer (for example, negative electrode layer 2 ) including the aforementioned negative electrode current collector.

[0017] (Effects of the Invention)

[0018] According to the above (1), since the amount of binder in the negative electrode side solid electrolyte layer is smaller than that in the first solid electrolyte layer, it is easy to cut the negative electrode side sheet member having the negative electrode side solid electrolyte layer. Therefore, it is easy to cut the negative electrode side sheet member, stack it, and transfer it to the positive electrode side sheet member, and it is easy to control the size to the desired design size.

[0019] According to the above (2), the positive electrode side sheet member contains more binder than the negative electrode side sheet member, and thus can be pressed at a higher pressure than the negative electrode side sheet member. As a result, the solid battery 1 can be efficiently manufactured by conveying the positive electrode side sheet member in an uncut state and integrating it with the cut negative electrode side sheet member.

[0020] According to the above (3), the positive electrode side sheet member contains more binder than the negative electrode side sheet member, so it can be pressed multiple times. By pressing multiple times, the electrode becomes dense and can be formed to have a high energy density.

[0021] According to the above (4), in order to improve the energy density, the positive electrode side sheet member contains a large amount of positive electrode active material layer 31 and is formed thick. Therefore, by transporting the positive electrode side sheet member in an uncut state and integrating it with the cut negative electrode side sheet member, the solid battery 1 can be manufactured efficiently.

[0022] According to (5) above, by including the second solid electrolyte layer between the negative electrode side solid electrolyte layer and the first solid electrolyte layer SE1, it becomes easy to stably adhere the negative electrode side solid electrolyte layer having a relatively small amount of binder to the first solid electrolyte layer via the second solid electrolyte layer.

[0023] According to the above (6), a solid battery with high energy density can be provided.

[0024] According to the above (7), when the solid battery 1 is a lithium metal battery, lithium metal can be uniformly deposited, and the interface between the intermediate layer and the solid electrolyte layer can be stabilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1This is a diagram showing a cross section of the solid state battery according to this embodiment.

[0026] Figure 2 This is a diagram illustrating a solid state battery manufacturing system according to this embodiment.

[0027] Figure 3 This is a diagram showing a portion of a solid battery manufacturing system according to this embodiment.

[0028] Figure 4 This is a diagram illustrating the flow of a method for manufacturing a solid state battery according to this embodiment.

[0029] Figure 5 It is a diagram for explaining the positions at which the layers constituting the solid battery of this embodiment are cut.

[0030] Figure 6A This is a diagram illustrating the dimensional accuracy of the layers constituting the positive electrode side sheet member of the present embodiment.

[0031] Figure 6B This is a diagram illustrating the dimensional accuracy of the layers constituting the negative electrode side sheet member of the present embodiment. DETAILED DESCRIPTION

[0032] [Solid-state battery]

[0033] like Figure 1 As shown, the solid battery 1 manufactured by the manufacturing method of the present invention is a fully solid battery having an electrode 10 in which a negative electrode layer 2, a solid electrolyte layer 4 and a positive electrode layer 3 are stacked in sequence. Figure 1 The structure in which the negative electrode layer 2, the solid electrolyte layer 4, the positive electrode layer 3, the solid electrolyte layer 4, and the negative electrode layer 2 are stacked in this order is described as the stacked structure of the solid battery 1. However, the structure of the solid battery 1 is not limited to the above. Figure 1 In addition to the illustrated electrode 10 , the solid battery 1 may have a structure such as an exterior body that can be used in a solid battery.

[0034] The solid electrolyte layer 4 in the solid battery 1 includes at least a first solid electrolyte layer SE1 disposed on the positive electrode layer 3 side and a negative electrode-side solid electrolyte layer SE3 disposed on the negative electrode layer 2 side. The solid electrolyte layer 4 may also include a second solid electrolyte layer SE2 disposed adjacent to the first solid electrolyte layer SE1. In this embodiment, the solid electrolyte layer 4 is described as being composed of the above three layers. An intermediate layer 5 may also be optionally disposed between the negative electrode layer 2 and the solid electrolyte layer 4.

[0035] The solid battery 1 is not particularly limited and may be a lithium ion solid secondary battery or a lithium metal secondary battery.

[0036] (Negative electrode layer)

[0037] The negative electrode layer 2 includes a negative electrode active material layer 21 and a negative electrode current collector layer 22. The negative electrode active material layer 21 is not particularly limited and can be composed of a material that can be used as a negative electrode active material for the solid battery 1. Examples of negative electrode active materials constituting the negative electrode active material layer 21 include lithium metal, lithium alloys, silicon-based active materials such as Si and Si alloys, lithium titanate (Li4Ti5O 12 ) and other lithium transition metal oxides, TiO2, Nb2O3 and WO3 and other transition metal oxides, metal sulfides, metal nitrides, graphite, soft carbon and hard carbon and other carbon materials, metal indium, etc.

[0038] In addition to the above, the negative electrode active material layer 21 may also contain materials that can be contained in the negative electrode active material layer 21 of the solid battery 1. As the above materials, for example, solid electrolytes, conductive additives, adhesives, etc. can be listed. As solid electrolytes, substances similar to the solid electrolytes contained in the solid electrolyte layer 4 described later can be listed. As conductive additives, carbon black, natural graphite, carbon fibers, carbon nanotubes, etc. can be listed. As adhesives, nitrile polymers, polyester polymers, acrylic polymers, cellulose polymers, styrene polymers, styrene butadiene polymers, vinyl acetate polymers, urethane polymers, fluoroethylene polymers, etc. can be listed.

[0039] The negative electrode current collector layer 22 is not particularly limited and can be made of copper, nickel, stainless steel, or the like. Examples of the shape of the negative electrode current collector layer 22 include foil, plate, mesh, non-woven fabric, and foam. In this embodiment, the negative electrode current collector layer 22 is composed of a negative electrode current collector foil 221 serving as a negative electrode current collector.

[0040] (Solid electrolyte layer)

[0041] The solid electrolyte layer 4 is formed between the negative electrode layer 2 and the positive electrode layer 3. In this embodiment, the solid electrolyte layer 4 has a structure in which a first solid electrolyte layer SE1 arranged in contact with the positive electrode layer 3, a second solid electrolyte layer SE2, and a negative electrode side solid electrolyte layer SE3 arranged on the negative electrode layer 2 side are stacked in this order.

[0042] The first solid electrolyte layer SE1 is arranged to abut the positive electrode active material layer 31 in the positive electrode layer 3. The solid electrolyte constituting the first solid electrolyte layer SE1 is not particularly limited, as long as it is a material that can be used as an electrolyte for a solid battery. For example, sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, inorganic solid electrolytes such as those containing lithium salts, or polymer-based solid electrolytes such as polyethylene oxide can be used. These solid electrolytes can be used alone or in combination of two or more.

[0043] The first solid electrolyte layer SE1 contains a binder in addition to the solid electrolyte material. The binder can be the same as that contained in the negative electrode active material layer 21. The binder content in the first solid electrolyte layer SE1 relative to the total mass of the first solid electrolyte layer SE1 is equal to or greater than the binder content in the second solid electrolyte layer SE2 relative to the total mass of the second solid electrolyte layer SE2. The upper limit of the binder content in the first solid electrolyte layer SE1 is, for example, 25% by mass. The binder content in the first solid electrolyte layer SE1 is preferably 10 to 30% by mass. This allows the first solid electrolyte layer SE1 to easily follow the extension of the positive electrode layer 3 during pressing. Furthermore, the pressing pressure in the transfer pressing step, described later, can be reduced.

[0044] The first solid electrolyte layer SE1 may contain, in addition to the solid electrolyte material and the binder, materials that can be used in the solid electrolyte layer of a solid battery.

[0045] The thickness of the first solid electrolyte layer SE1 (the length of each layer in the stacking direction) is preferably thinner than the thickness of the second solid electrolyte layer SE2. The thickness of the first solid electrolyte layer SE1 is preferably 3 to 15 μm, for example.

[0046] The second solid electrolyte layer SE2 is an arbitrarily configured layer, positioned adjacent to the first solid electrolyte layer SE1. The solid electrolyte material constituting the second solid electrolyte layer SE2 is not particularly limited, and the same material as that constituting the first solid electrolyte layer SE1 can be used. Like the first solid electrolyte layer SE1, the second solid electrolyte layer SE2 may also contain a binder or the like in addition to the solid electrolyte material. The binder content of the second solid electrolyte layer SE2 is less than that of the first solid electrolyte layer SE1. The binder content of the second solid electrolyte layer SE2 is preferably 10-30% by mass. This can improve the energy density of the solid battery 1. The second solid electrolyte layer SE2 may also include a support. The support may be a three-dimensional structure such as a mesh, woven fabric, non-woven fabric, embossed body, punched body, expanded body, or foamed body. The second solid electrolyte layer SE2 may also not include the support.

[0047] The thickness of the second solid electrolyte layer SE2 (the length of each layer in the stacking direction) is preferably greater than the thickness of the first solid electrolyte layer SE1. Furthermore, the thickness of the second solid electrolyte layer SE2 (the length of each layer in the stacking direction) is preferably greater than the thickness of the negative-electrode solid electrolyte layer SE3, described later. The thickness of the second solid electrolyte layer SE2 is preferably, for example, 10 to 50 μm.

[0048] The negative electrode side solid electrolyte layer SE3 is arranged on the negative electrode layer side. The negative electrode side solid electrolyte layer SE3 is arranged adjacent to the negative electrode layer 2. Figure 1 As shown, when the solid battery 1 includes the intermediate layer 5 , the negative electrode side solid electrolyte layer SE3 is arranged adjacent to the intermediate layer 5 .

[0049] The solid electrolyte material constituting the negative-electrode solid electrolyte layer SE3 is not particularly limited, and the same solid electrolyte material as that constituting the first solid electrolyte layer SE1 can be used. The binder content of the negative-electrode solid electrolyte layer SE3 is preferably 1.3 to 8.7% by mass. In terms of volume percent, the binder content of the negative-electrode solid electrolyte layer SE3 is preferably 2.7% to 10% by volume. The binder content of the negative-electrode solid electrolyte layer SE3 is lower than that of the first solid electrolyte layer SE1.

[0050] The thickness of the negative electrode side solid electrolyte layer SE3 (the length of each layer in the stacking direction) is preferably thinner than the thickness of the second solid electrolyte layer SE2. The thickness of the negative electrode side solid electrolyte layer SE3 is preferably 3 to 8.5 μm, for example.

[0051] (positive electrode layer)

[0052] The positive electrode layer 3 includes a positive electrode active material layer 31 and a positive electrode current collector layer 32. In this embodiment, the positive electrode layer 3 has a structure in which two positive electrode active material layers 31 are stacked on both sides of a single positive electrode current collector layer 32. However, the structure of the positive electrode layer 3 is not limited to the above structure, and a structure in which a single positive electrode active material layer 31 is stacked on a single side of a single positive electrode current collector layer 32 may also be used.

[0053] The positive electrode active material layer 31 is not particularly limited and can be composed of a material that can be used as a positive electrode active material for a solid battery. Examples of the positive electrode active material constituting the positive electrode active material layer 31 include LiCoO2, LiNiO2, LiCo x Ni y Mn z O2(x+y+z=1), LiVO2, LiCrO2 and other layered positive electrode active material particles; LiMn2O4, Li(Ni 0.25 Mn 0.75)2O4, LiCoMnO4, Li2NiMn3O8 and other spinel positive electrode active materials; LiCoPO4, LiMnPO4, LiFePO4 and other olivine positive electrode active materials; solid solution oxides (Li2MnO3-LiMO2 (M is Co, Ni, etc.)), polyaniline, polypyrrole and other conductive polymers; sulfides such as Li2S, CuS, Li-Cu-S compounds, TiS2, FeS, MoS2, Li-Mo-S compounds; mixtures of sulfur and carbon; etc. The above-mentioned positive electrode active materials may use one of the above-mentioned materials or a structure composed of two or more of the above-mentioned materials.

[0054] The positive electrode active material layer 31 may also contain a binder, etc. The binder content of the positive electrode active material layer 31 is preferably 0.5 to 5% by mass, and more preferably, 2.56% by mass. The thickness of the positive electrode active material layer 31 (the length of each layer in the stacking direction) is preferably, for example, 80 to 100 μm. This can increase the battery capacity of the solid state battery 1.

[0055] You can also Figure 5 As shown, an insulating frame 6 is provided on the outer periphery of the positive electrode active material layer 31. The insulating frame 6 can prevent short circuits in the solid battery 1 and improve strength. In the completed state of the solid battery 1, the insulating frame 6 is configured to cover the side surfaces of the two positive electrode active material layers 31 formed on both sides of the positive electrode collector layer 32. The material constituting the insulating frame 6 is not particularly limited, and examples thereof include insulating oxides such as alumina, resins such as polyvinylidene fluoride (PVDF), and rubbers such as styrene-butadiene rubber (SBR).

[0056] The positive electrode current collector layer 32 is not particularly limited and can be made of, for example, aluminum, stainless steel, conductive carbon (graphite, carbon nanotubes, etc.). Examples of the shape of the positive electrode current collector layer 32 include foil, plate, mesh, non-woven fabric, and foam. In this embodiment, the positive electrode current collector layer 32 is composed of a positive electrode current collector foil 321 serving as the positive electrode current collector.

[0057] (Middle layer)

[0058] The intermediate layer 5 is disposed between the negative electrode layer 2 and the solid electrolyte layer 4. For example, if the solid battery 1 is a lithium metal battery, the intermediate layer 5 has the function of uniformly depositing lithium metal. Thus, the interface between the intermediate layer 5 and the solid electrolyte layer 4 is stabilized. If the solid battery 1 is a lithium metal secondary battery having the intermediate layer 5, the solid battery 1 may also be an anode-less battery in which the negative electrode active material layer 21 is not present during initial charge. In this case, after the initial charge and discharge, a lithium metal layer is formed as the negative electrode active material layer 21.

[0059] The material constituting the intermediate layer 5 is not particularly limited, and examples thereof include metals or amorphous carbon that can be alloyed with lithium. Examples of metals that can be alloyed with lithium include tin (Sn), silicon (Si), zinc (Zn), magnesium (Mg), gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), and antimony (Sb). Metals that can be alloyed with lithium may also be nanoparticles. Examples of amorphous carbon include carbon blacks such as acetylene black, furnace black, and Ketjen black, coke, and activated carbon. Amorphous carbon may be either easily graphitized carbon (soft carbon) or difficultly graphitized carbon (hard carbon), CNTs (carbon nanotubes), fullerenes, or graphene. In addition to the above-mentioned substances, the intermediate layer may also include a binder.

[0060] A manufacturing system 100 for manufacturing the above-described solid battery 1 will be described. Figure 2 The manufacturing system 100 of the solid battery 1 of this embodiment is shown. The manufacturing system 100 includes a first positive electrode side transfer roller 310, a second positive electrode side transfer roller 320, and an intermediate layer transfer roller 370 (see Figure 3 )、Negative electrode side transfer roller 330 (refer to Figure 3 ), negative electrode side sheet component stacking roller 340, positive electrode pressing device 350 and integrated pressing device 360, the positive electrode side sheet component 300 is sent in one direction by each roller mentioned above to continuously manufacture the solid battery 1. Figure 1 , shows the range of being pressed or transfer-pressed in the later-described positive electrode pressing step S3, the second solid electrolyte layer transfer step S4, the intermediate layer transfer step S5, the negative electrode side solid electrolyte layer transfer step S6, and the integrated pressing step S9 as an integrated step.

[0061] The positive electrode side sheet member 300 is a sheet-shaped member formed by laminating the positive electrode active material layer 31 on the positive electrode current collector foil 321 constituting the positive electrode current collector layer 32. After production, the positive electrode side sheet member 300 constitutes the positive electrode layer 3 of the solid-state battery 1. The positive electrode side sheet member 300 is fed by rollers (not shown) and conveyed so as to extend continuously from the base end to the end of the solid-state battery 1 production line.

[0062] The first positive electrode transfer roller 310, the second positive electrode transfer roller 320, the intermediate layer transfer roller 370, the negative electrode transfer roller 330, and the negative electrode sheet laminating roller 340 each consist of a pair of rotating rollers. These rollers 310, 320, 370, and 330 pressurize a sheet material (such as a substrate to be transferred) and a sheet material having a solid electrolyte layer to be transferred, by passing the sheet material between the rollers under pressure. The negative electrode sheet laminating roller 340 positions the sheet material while passing it between the rollers.

[0063] The positive electrode pressing device 350 and the integrated pressing device 360 ​​are each composed of a pair of rotating rollers, similar to the transfer roller, and are devices that make the positive electrode side sheet component 300 stacked with a solid electrolyte layer, etc. pass through a pair of rollers in a pressurized state according to the process to achieve high density.

[0064] like Figure 2 As shown, these rollers are arranged in order from the upstream side along the feeding direction of the positive electrode side sheet member 300: a first positive electrode side transfer roller 310, a positive electrode pressing device 350, a second positive electrode side transfer roller 320, a negative electrode side sheet member laminating roller 340, and an integrated pressing device 360. When the solid battery 1 has the second solid electrolyte layer SE2, the second positive electrode side transfer roller 320 is arranged between the positive electrode pressing device 350 and the negative electrode side sheet member laminating roller 340.

[0065] The intermediate layer transfer roller 370 and the negative electrode transfer roller 330 are positioned at a distance from the feed line L of the positive electrode side sheet member 300 and perform transfer pressing of the intermediate layer 5 or the negative electrode side solid electrolyte layer SE3. As described later, the formed intermediate layer 5 and negative electrode layer 2 are then conveyed toward the upper or lower surface of the positive electrode side sheet member 300, merge with the feed line L of the positive electrode side sheet member 300, and are stacked by the negative electrode side sheet member stacking roller 340.

[0066] The method for manufacturing a solid-state battery 1 using the above-described system 100 for manufacturing a solid-state battery 1 will now be described. The method for manufacturing a solid-state battery 1 includes a positive electrode side sheet component forming step S30 and a negative electrode side sheet component forming step S40. The positive electrode side sheet component forming step S30 is a step for forming a positive electrode side sheet component 300 that includes at least a positive electrode current collector layer, i.e., a positive electrode current collector foil 321, and a positive electrode active material layer 31. The method includes a positive electrode side sheet component feeding step S1, a first solid electrolyte layer transfer step S2, a positive electrode pressing step S3, and a second solid electrolyte layer transfer step S4, which will be described later. The negative electrode side sheet component forming step S40 is a step for forming a negative electrode side sheet component that includes at least a negative electrode current collector, i.e., a negative electrode current collector foil 221, and a negative electrode side solid electrolyte layer SE3. The method includes an intermediate layer transfer step S5, a negative electrode side solid electrolyte layer transfer step S6, and a negative electrode side sheet component cutting step S7, which will be described later.

[0067] First, the positive electrode side sheet member 300 , which is formed by coating and laminating the positive electrode active material on the positive electrode current collector foil 321 constituting the positive electrode current collector layer 32 , is conveyed by conveying rollers (not shown) (positive electrode side sheet member feeding step S1 ).

[0068] In addition, if Figure 5As shown, an insulating frame 6 is formed on the positive electrode side sheet member 300 and the positive electrode current collector foil 321 according to the designed dimensions of the solid battery 1 after completion. The insulating frame 6 is arranged in a frame shape, and the positive electrode active material layer 31 is intermittently applied and arranged in the frame.

[0069] Next, the first solid electrolyte layer SE1 is transferred onto the positive electrode side sheet member 300 using the first positive electrode side transfer roller 310 (first solid electrolyte layer transfer step S2). The first solid electrolyte layer transfer step S2 includes a positioning step S21 and a transfer pressing step S22. In the positioning step S21, the first solid electrolyte layer SE1 is positioned on the positive electrode side sheet member 300 so that it is within the range guided by a guide roller (not shown). In the transfer pressing step S22, the slurry constituting the first solid electrolyte layer SE1 is pressurized and passed through the positive electrode side sheet member 300 using the first positive electrode side transfer roller 310 as a transfer roller to perform transfer pressing. The pressure at this time can be, for example, 50 to 500 MPa at room temperature (e.g., 10 to 35°C). Preferably, it can be 100 MPa at 25°C.

[0070] Next, the positive electrode side sheet member 300, onto which the first solid electrolyte layer SE1 has been transferred, is pressed using the positive electrode pressing device 350 (positive electrode pressing step S3). This positive electrode pressing step S3 densifies the positive electrode. To achieve this high density, the pressing pressure is approximately 800 to 1200 MPa at temperatures between 25 and 100 degrees Celsius. The stack of the densified positive electrode side sheet member 300 and the first solid electrolyte layer SE1 is transported downstream along the delivery line L.

[0071] After the positive electrode pressing step S3, the second solid electrolyte layer SE2 is transferred to the positive electrode side sheet member 300 to which the first solid electrolyte layer SE1 has been transferred and pressed using the second positive electrode side transfer roller 320 (second solid electrolyte layer transfer step S4). The second solid electrolyte layer transfer step S4 includes a positioning step S41 and a transfer pressing step S42. In the positioning step S41, the second solid electrolyte layer SE2 is positioned on the positive electrode side sheet member 300 to which the first solid electrolyte layer SE1 has been transferred, so that it is positioned within a range guided by a guide roller (not shown). In the transfer pressing step S42, the slurry constituting the second solid electrolyte layer SE2 is pressurized and passed through the positive electrode side sheet member 300 using the second positive electrode side transfer roller 320, acting as a transfer roller, for transfer pressing. The pressure at this time can be set to 50 to 500 MPa at room temperature (e.g., 10 to 35°C). Preferably, it may be 150 MPa at 25°C.

[0072] On the other hand, the negative electrode side sheet member 400 is prepared at a position spaced apart from the delivery line L. First, as shown in FIG. Figure 3 As shown in the upper part of FIG, the intermediate layer 5 is transferred onto the negative electrode layer 2 composed of the negative electrode active material layer 21 stacked on the negative electrode current collector foil 221 by the intermediate layer transfer roller 370 (intermediate layer transfer step S5). Then, as shown in FIG. Figure 3 As shown in the lower portion of FIG, the negative electrode side solid electrolyte layer SE3 is transferred onto the intermediate layer 5 by the negative electrode side transfer roller 330 to form the negative electrode side sheet member 400 (negative electrode side solid electrolyte layer transfer step S6). This process places the intermediate layer 5 between the negative electrode active material layer 21 and the negative electrode side solid electrolyte layer SE3.

[0073] The intermediate layer transfer step S5 includes an intermediate layer alignment step S51 and an intermediate layer transfer pressing step S52. In the intermediate layer alignment step S51, the slurry constituting the intermediate layer 5 is aligned on the negative electrode active material layer 21 so as to be positioned within a range guided by a guide roller (not shown). In the intermediate layer transfer pressing step S52, the intermediate layer 5 is pressurized and passed over the negative electrode active material layer 21 by the intermediate layer transfer roller 370, which serves as a transfer roller, to transfer the intermediate layer 5 to the negative electrode active material layer 21. The pressure at this time can be set to 50 to 800 MPa at room temperature (e.g., 10 to 35°C), and more preferably, within a range of 300 MPa to 800 MPa at 25°C.

[0074] The negative electrode side solid electrolyte layer transfer step S6 includes a negative electrode side solid electrolyte layer alignment step S61 and a negative electrode side solid electrolyte layer transfer pressing step S62. In the negative electrode side solid electrolyte layer alignment step S61, the slurry constituting the negative electrode side solid electrolyte layer SE3 is aligned on the intermediate layer 5 so that it is positioned within a range guided by guide rollers (not shown). In the negative electrode side solid electrolyte layer transfer pressing step S62, the negative electrode side transfer roller 330, acting as a transfer roller, presses the negative electrode side solid electrolyte layer SE3 over the intermediate layer 5 and passes it through the intermediate layer 5, thereby transferring the negative electrode side solid electrolyte layer SE3 to the intermediate layer 5 and performing negative electrode active material layer transfer pressing. This results in a sheet-like component 400a formed by laminating the negative electrode layer 2, the intermediate layer 5, and the negative electrode side solid electrolyte layer SE3. The pressure at this time can be set to 600 to 800 MPa at room temperature (e.g., 10 to 35°C).

[0075] Regarding pressure, the pressing pressure in the positive electrode pressing step S3 is not only the maximum pressure applied to the positive electrode side sheet member 300, but also the maximum pressure applied during the entire manufacturing process of the solid battery 1. To increase energy density, the positive electrode side sheet member 300 is densified and pressed at high pressure. The maximum pressing pressure in the positive electrode pressing step S3 is greater than the maximum pressing pressure applied to the negative electrode side sheet member 400.

[0076] Furthermore, the pressure during the transfer of the first solid electrolyte layer transfer step S2 and the second solid electrolyte layer transfer step S4 is lower than the pressing pressure during the positive electrode pressing step S3. Furthermore, the pressure during the transfer of the first solid electrolyte layer transfer step S2 and the second solid electrolyte layer transfer step S4 is lower than the pressing pressure during the negative electrode side solid electrolyte layer transfer step S6.

[0077] Because the first solid electrolyte layer SE1 and the second solid electrolyte layer SE2 contain a relatively large amount of binder, the pressing pressure during transfer can be reduced. Furthermore, by setting the transfer pressing pressure as low as possible, the amount of extension of the first solid electrolyte layer SE1 and the second solid electrolyte layer SE2 caused by the transfer pressing can be minimized. Consequently, in subsequent integration pressing steps S9 and the like, there is room for the first solid electrolyte layer SE1 and the second solid electrolyte layer SE2 to extend, allowing the first solid electrolyte layer SE1 to extend in line with the positive electrode layer 3. This improves the bonding between the first solid electrolyte layer SE1 and the positive electrode active material layer 31.

[0078] like Figure 6A As shown, the positive electrode layer 3 (positive electrode collector layer 32 and positive electrode active material layer 31), the first solid electrolyte layer SE1, and the second solid electrolyte layer SE2 of the positive electrode side sheet component 300 are densified by the positive electrode pressing step S3 or the integrated pressing step S9, so they are pressed at a high pressure to reach the designed size at the pressing stage.

[0079] After the negative electrode side solid electrolyte layer transfer step S6, the obtained negative electrode layer 2, the intermediate layer 5 and the negative electrode side solid electrolyte layer SE3 are stacked in a continuous sheet-like component 400a, which is supported by a roll for unwinding the component transferred in the negative electrode side solid electrolyte layer transfer step S6, and is cut by a cutter (negative electrode side sheet component cutting step S7). The sheet-like component 400a is cut to the design size of the negative electrode layer 2 of the solid battery 1. Figure 5 As shown, in order to prevent short circuits, the sheet-like member 400 a is cut slightly smaller than the size of the positive electrode side sheet member 300 cut in a cutting step S10 described later, thereby forming the negative electrode side sheet member 400 .

[0080] like Figure 6B As shown, the particles of the negative electrode layer 2 , the intermediate layer 5 and the negative electrode side solid electrolyte layer SE3 are finer and softer than those of the positive electrode layer 3 , and thus they are cut into the designed size by the negative electrode side sheet member cutting step S7 .

[0081] like Figure 2 and Figure 4 As shown, the negative electrode side sheet member 400, cut to the designed dimensions, is conveyed to the positive electrode side sheet member 300 so as to merge with the delivery line L of the positive electrode side sheet member 300 and is stacked on the positive electrode side sheet member 300. At this time, prior to the integration pressing step S9 described later, the first solid electrolyte layer SE1 is provided on the lower side of the surface of the positive electrode side sheet member 300 facing the negative electrode side solid electrolyte layer SE3, and the second solid electrolyte layer SE2 is provided thereon. The negative electrode side sheet member 400, in its cut state, is then placed on the positive electrode side sheet member 300. Specifically, the negative electrode side sheet member 400, to which the negative electrode side solid electrolyte layer SE3 has been transferred, is conveyed by the negative electrode side sheet member stacking roller 340 and stacked on the positive electrode side sheet member 300, to which the first solid electrolyte layer SE1 and the second solid electrolyte layer SE2 have been transferred (negative electrode side sheet member stacking step S8). During the negative electrode side sheet lamination, the negative electrode side sheet 400 cut to a designed size is aligned on the positive electrode side sheet 300 to which the first solid electrolyte layer SE1 and the second solid electrolyte layer SE2 are transferred so as to be arranged within a range guided by guide rollers (not shown).

[0082] In this manner, the positive electrode side sheet component 300 and the negative electrode side sheet component 400 are stacked and pressed using the integration pressing device 360 ​​to integrate the electrode 10 (integration pressing step S9). In this manner, the positive electrode side sheet component 300 is pressed at least twice, including the transfer step and the pressing step. Immediately before the integration pressing step S9, the thickness of the negative electrode side sheet component 400 in the stacking direction of the positive electrode side sheet component 300 is greater than that of the negative electrode side sheet component 400. The pressure at this time is, for example, approximately 500 to 900 MPa at temperatures between 25 and 100 degrees Celsius. The integration pressing step S9 integrates the positive electrode side sheet component 300 and the negative electrode side sheet component 400, while also increasing the density of the first solid electrolyte layer SE1, the second solid electrolyte layer SE2, and the negative electrode side solid electrolyte layer SE3. When the pressing pressures of the integrated pressing step S9 and the positive electrode pressing step S3 are compared, the pressing pressure of the positive electrode pressing step S3 is higher than the pressing pressure of the integrated pressing step S9 .

[0083] After the integrated pressing step S9 , the formed electrode 10 is cut using a rotary cutter (cutting step S10 ).

[0084] The transfer of the first solid electrolyte layer SE1 in the first solid electrolyte layer transfer step S2, the pressing of the positive electrode side sheet component 300 in the positive electrode pressing step S3, the transfer of the second solid electrolyte layer SE2 in the second solid electrolyte layer transfer step S4, the lamination of the negative electrode side sheet component 400 before integration in the negative electrode side sheet component lamination step S8, and the integration pressing in the integration pressing step S9 are performed on both sides of the positive electrode side sheet component 300 fed out in the positive electrode side sheet component feeding step S1. Figure 1 As shown, the solid battery 1 has layers stacked symmetrically on the upper and lower surfaces.

[0085] As described above, the first solid electrolyte layer transfer step S2, the second solid electrolyte layer transfer step S4, the positive electrode pressing step S3, the negative electrode side sheet component lamination step S8, and the integrated pressing step S9 are performed continuously on the positive electrode side sheet component 300 fed out by the positive electrode side sheet component feeding step S1. The negative electrode side sheet component forming step S40 is performed at a distance from the positive electrode side sheet component 300, but the formed negative electrode side sheet component 400 is arranged so as to merge with the positive electrode side sheet component 300. The method for manufacturing the solid battery 1 is formed by a series of continuous processes.

[0086] According to this embodiment, the following effects are achieved.

[0087] (1) The manufacturing method of the solid battery 1 is configured to include: a negative electrode side sheet component forming step S40, forming a negative electrode side sheet component 400 including at least a negative electrode collector foil 221 and a negative electrode side solid electrolyte layer SE3; a positive electrode side sheet component forming step S30, forming a positive electrode side sheet component 300 including at least a positive electrode collector foil 321 and a positive electrode active material layer 31; and an integration pressing step S9, stacking and integrating the negative electrode side sheet component 400 and the positive electrode side sheet component 300. The negative electrode side sheet component forming step S40 is configured to include: a negative electrode side solid electrolyte layer transfer step S6, pressing at least the negative electrode collector foil 221 and the negative electrode side solid electrolyte layer SE3 to obtain a negative electrode side laminate; and a negative electrode side sheet component cutting step S7, cutting the laminate; and the positive electrode side sheet component forming step S30 is configured to include: a positive electrode pressing step S3, pressing at least the positive electrode collector foil 321 and the positive electrode active material layer 31. Before the integration pressing step S9 , the first solid electrolyte layer SE1 is provided on the surface of the positive electrode side sheet member 300 facing the negative electrode side solid electrolyte layer SE3 , and the binder content of the negative electrode side solid electrolyte layer SE3 is set lower than that of the first solid electrolyte layer SE1 .

[0088] Since the amount of binder in the negative electrode side solid electrolyte layer SE3 is smaller than that in the first solid electrolyte layer SE1, the negative electrode side sheet member 400 having the negative electrode side solid electrolyte layer SE3 can be easily cut. Therefore, it is easy to cut the negative electrode side sheet member 400, stack it, and transfer it to the positive electrode side sheet member 300, making it easy to control the size to the desired design size.

[0089] (2) According to this embodiment, the maximum pressing pressure in the positive electrode pressing step S3 is configured to be at least equal to or greater than the maximum pressing pressure in the negative electrode side solid electrolyte layer transfer step S6. Since the positive electrode side sheet member 300 contains more binder than the negative electrode side sheet member 400, it can be pressed at a higher pressure than the negative electrode side sheet member 400. Thus, the solid battery 1 can be efficiently manufactured by transporting the positive electrode side sheet member 300 without cutting it and integrating it with the cut negative electrode side sheet member 400.

[0090] (3) According to this embodiment, the positive electrode side sheet member 300 is pressed twice or more. Since the positive electrode side sheet member 300 contains more binder than the negative electrode side sheet member 400, it can be pressed multiple times. By pressing multiple times, the electrode becomes denser, resulting in a higher energy density.

[0091] (4) According to this embodiment, the thickness of the positive electrode side sheet member 300 in the stacking direction is greater than that of the negative electrode side sheet member 400. In order to improve energy density, the positive electrode side sheet member 300 contains a large amount of positive electrode active material layer 31 and is formed thick. Therefore, by transporting the positive electrode side sheet member 300 without cutting and integrating it with the cut negative electrode side sheet member 400, the solid battery 1 can be manufactured efficiently.

[0092] (5) According to this embodiment, the second solid electrolyte layer transfer step S4 is performed before the integrated pressing step S9. The second solid electrolyte layer SE2 is stacked and transferred between the negative electrode side solid electrolyte layer SE3 and the first solid electrolyte layer SE1. The second solid electrolyte layer SE2 has a higher binder content than the negative electrode side solid electrolyte layer SE3. By including the second solid electrolyte layer SE2 between the negative electrode side solid electrolyte layer SE3 and the first solid electrolyte layer SE1, it is easier to stably attach the negative electrode side solid electrolyte layer SE3, which has a relatively small amount of binder, to the first solid electrolyte layer SE1 via the second solid electrolyte layer SE2.

[0093] (6) According to the present embodiment, the negative electrode side sheet member 400 is configured to include the negative electrode active material layer 21. This makes it possible to provide a solid battery 1 having a high energy density.

[0094] (7) According to this embodiment, the intermediate layer transfer step S5 is included, in which the intermediate layer 5 is stacked and transferred on the negative electrode layer 2 including the negative electrode current collector foil 221. Thus, when the solid battery 1 is a lithium metal battery, lithium metal can be uniformly deposited, and the interface between the intermediate layer 5 and the solid electrolyte layer 4 can be stabilized.

[0095] The present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the objectives of the present invention are encompassed by the present invention. For example, in the above-described embodiment, the negative electrode side sheet member 400 includes a laminated body formed by laminating the negative electrode current collector foil 221, the negative electrode active material layer 21, the intermediate layer 5, and the negative electrode side solid electrolyte layer SE3. However, the negative electrode active material layer 21 and the intermediate layer 5 may not be included.

[0096] Reference numerals

[0097] 1 Solid-state battery

[0098] 21 Negative electrode active material layer

[0099] 31. Positive electrode active material layer

[0100] SE1 First solid electrolyte layer

[0101] SE2 Second solid electrolyte layer

[0102] SE3 negative electrode side solid electrolyte layer

[0103] 400 Negative side piece components

[0104] S3 positive electrode pressing process

[0105] S5 Intermediate layer transfer process

[0106] S6 negative electrode side solid electrolyte layer transfer process

[0107] S7 Negative electrode side piece cutting process

[0108] S9 integrated pressing process (integrated process)

[0109] S40 Negative electrode side sheet component forming process

[0110] S30 Positive electrode side sheet component forming process

Claims

1. A method for manufacturing a solid battery, comprising: a negative electrode side sheet member forming step of forming a negative electrode side sheet member including at least a negative electrode current collector and a negative electrode side solid electrolyte layer; a positive electrode side sheet member forming step of forming a positive electrode side sheet member including at least a positive electrode current collector and a positive electrode active material layer; and In an integration step, the negative electrode side sheet component and the positive electrode side sheet component are stacked and integrated; and The negative electrode side sheet component forming step comprises: a negative electrode side solid electrolyte layer transfer step of transferring the negative electrode side solid electrolyte layer by pressing at least the negative electrode current collector; and A negative electrode side sheet component cutting step is to cut the sheet component obtained by transfer; The positive electrode side sheet component forming step comprises: A positive electrode pressing step of pressing at least the positive electrode current collector and the positive electrode active material layer; Before the integration step, a first solid electrolyte layer is provided on the surface of the positive electrode side sheet member facing the negative electrode side solid electrolyte layer. The negative electrode side solid electrolyte layer has a lower binder content than the first solid electrolyte layer.

2. The method for manufacturing a solid battery according to claim 1, wherein: The maximum value of the pressing pressure in the positive electrode pressing step is at least equal to or greater than the maximum value of the pressing pressure in the negative electrode side solid electrolyte layer transfer step.

3. The method for manufacturing a solid battery according to claim 1, wherein: The positive electrode side sheet member is pressed twice or more.

4. The method for manufacturing a solid battery according to claim 1, wherein: The thickness of the positive electrode side sheet member in the stacking direction is greater than that of the negative electrode side sheet member.

5. The method for manufacturing a solid battery according to claim 1, wherein: Before the aforementioned integration process, there is a second solid electrolyte layer transfer process, in which the second solid electrolyte layer is stacked and transferred between the aforementioned negative electrode side solid electrolyte layer and the aforementioned first solid electrolyte layer. Compared with the aforementioned negative electrode side solid electrolyte layer, the second solid electrolyte layer has a higher content of the aforementioned binder.

6. The method for manufacturing a solid battery according to claim 1, wherein: The negative electrode side sheet member includes a negative electrode active material layer.

7. The method for manufacturing a solid battery according to claim 1, wherein: The solid battery manufacturing method includes an intermediate layer transfer step of laminating and transferring an intermediate layer on the negative electrode layer including the negative electrode current collector.

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