Laminated electrode body, resin-fixed laminated electrode body and all-solid-state battery

Abstract

This invention relates to a stacked electrode body, a resin-fixed stacked electrode body, and an all-solid-state battery. A stacked electrode body is provided that allows for easy side coating with resin. The stacked electrode body is for use in an all-solid-state battery, comprising multiple electrode bodies stacked together. Each electrode body has a first electrode, a solid electrolyte layer, a second electrode, and a second current collector sequentially disposed on both sides of a first current collector. The electrode body has a phase difference portion including the first electrode, which extends laterally relative to the second electrode. In adjacent electrode bodies, the lengths of the portions of one phase difference portion extending relative to the second electrode in the direction of extension are different from those of the portions of another phase difference portion.

Description

Technical Field

[0001] This application relates to stacked electrode bodies, resin-fixed stacked electrode bodies, and all-solid-state batteries. Background Technology

[0002] In recent years, all-solid-state batteries, which offer higher safety than liquid batteries, have been under development. All-solid-state batteries are manufactured by stacking a positive current collector, a positive electrode, a solid electrolyte layer, a negative electrode, and a negative current collector. Furthermore, it is known that during the manufacture of all-solid-state batteries, these layers are fixed with resin to improve the battery's mechanical strength and moisture resistance.

[0003] For example, Patent Document 1 discloses a method for manufacturing an all-solid-state battery, comprising: a first step of stacking multiple current collector layers, a positive electrode layer, a solid electrolyte layer, and a negative electrode layer to obtain a stacked battery having two end faces and a side face in the stacking direction; a second step of supplying liquid resin only to the side face of the stacked battery; and a third step of curing the liquid resin, wherein, in the first step, at least one of the current collector layer, positive electrode layer, solid electrolyte layer, and negative electrode layer is extended relative to the other layers to form an extended layer, and multiple extended layers are extended on the side face of the stacked battery; in the second step, liquid resin is supplied only to the side face of the stacked battery, thereby allowing the liquid resin to enter the gap between one extended layer and the other extended layers. Furthermore, Patent Document 1 discloses a technique for allowing the liquid resin to enter the aforementioned gap by providing a depressurization step between the first and second steps, or a pressurization step between the second and third steps.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-220447

[0007] Patent Document 2: Japanese Patent Application Publication No. 2014-523102

[0008] Patent Document 3: Japanese Patent Application Publication No. 2000-124057 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] Patent Document 1 describes a technique for fixing the sides of a stacked battery with multiple protruding layers (phase difference portions) to resin. To ensure the resin fully penetrates the gaps between the protruding layers, a pressurization or depressurization process is employed. From the viewpoint of firmly fixing the stacked battery with phase difference portions, it is preferable to fill the gaps between the phase difference portions with resin. However, if the pressure is too low, it is difficult to ensure the resin fills sufficiently to the depth; conversely, if the pressure is too high, the resin may leak onto the electrode reaction surface. Therefore, when coating the sides of the stacked electrode body with phase difference portions with resin, performing either a pressurization or depressurization process presents a problem of difficulty in controlling the resin's formation.

[0011] Therefore, in view of the above-mentioned actual situation, the main objective of this disclosure is to provide a laminated electrode body that is easy to coat with resin on the sides.

[0012] Methods for solving problems

[0013] As a method for solving the above-mentioned problems, this disclosure provides a stacked electrode body, which is a stacked electrode body for an all-solid-state battery having multiple electrode bodies stacked together. The electrode body has a first electrode, a solid electrolyte layer, a second electrode, and a second current collector arranged sequentially on both sides of a first current collector. The electrode body has a phase difference portion including the first electrode, which extends from the side relative to the second electrode. In adjacent electrode bodies, the lengths of the portions of one phase difference portion and the portions of another phase difference portion that extend relative to the second electrode are different in the direction of extension.

[0014] In the aforementioned stacked electrode body, the length of the portion of the phase difference that extends relative to the second electrode in the extension direction can be increased or decreased in stages from one side of the stacking direction to the other, or it can be increased or decreased in stages from the center of the stacked electrode body to the outside of the stacking direction.

[0015] This disclosure provides a resin-fixed stacked electrode body formed by fixing the side surfaces of the aforementioned stacked electrode body with resin. Furthermore, this disclosure provides an all-solid-state battery having the aforementioned resin-fixed stacked electrode body.

[0016] Invention Effects

[0017] In the stacked electrode body disclosed herein, the lengths of the portions of one phase difference section and the portions of another phase difference section extending outward relative to the second electrode (extending portions) are different in the extending direction. That is, adjacent phase difference sections are stepped. Therefore, it is easy to coat the side of the stacked electrode body with resin. For example, it can be shaped so that resin can be coated to the side without tilting the electrode. In addition, the stacked electrode body of this disclosure does not require pressurization or depressurization to coat the resin as in Patent Document 1, so resin leakage to the electrode reaction surface is suppressed, and electrode displacement when resin is coated to the side is also suppressed. Furthermore, by being able to easily coat the side of the stacked electrode body with resin, the risk of short circuits caused by powder shedding from the electrode side after resin fixation is also suppressed.

[0018] It should be noted that the protruding portions of adjacent phase difference portions in the stacked electrode body of this disclosure have different lengths, thus resulting in poor positioning performance, but the shape can be controlled by resin coating. For example, positioning performance is improved by making the shape quadrilateral.

[0019] Furthermore, Patent Documents 2 and 3 describe stacked electrode bodies with altered electrode body size and stepped structures, but they do not have a phase difference portion like the stacked battery in Patent Document 1. Therefore, it is believed that the aforementioned problems do not occur in the electrode bodies of Patent Documents 2 and 3. Attached Figure Description

[0020] Figure 1 This is a three-dimensional view of the stacked electrode body 100.

[0021] Figure 2 This is a cross-sectional view of the stacked electrode body 100.

[0022] Figure 3 This is a cross-sectional view of the stacked electrode body 100'.

[0023] Figure 4 Cross-sectional view of resin-fixed laminated electrode bodies 200 and 200'.

[0024] Figure 5 This is a schematic diagram of each electrode body after the cutting process is completed.

[0025] Figure 6 shows the resin curing process.

[0026] Explanation of reference numerals in the attached figures

[0027] 1 First collector

[0028] 2. Electrode 1

[0029] 3. Solid electrolyte layer

[0030] 4. Second electrode

[0031] 5. Second collector

[0032] 6. Phase difference

[0033] 10 Electrode Body

[0034] 100, 100' stacked electrode body

[0035] 110 resin

[0036] 200, 200' Resin-fixed laminated electrode body Detailed Implementation

[0037] [Layered Electrode Body]

[0038] The stacked electrode body of this disclosure will be described with reference to a stacked electrode body 100 as one embodiment. Figure 1 A perspective view of the stacked electrode body 100 is shown. Additionally, Figure 2 The figure shows a cross-sectional view of the stacked electrode body 100.

[0039] like Figure 2 As shown, the stacked electrode body 100 is a stacked electrode body for all-solid-state batteries, which has multiple electrode bodies 10 on both sides of the first current collector 1, wherein a first electrode 2, a solid electrolyte layer 3, a second electrode 4 and a second current collector 5 are respectively arranged sequentially. Figure 1 , Figure 2 The diagram shows a stacked electrode body 100 with three electrode bodies 10 stacked together. However, there is no particular limitation on the number of stacked electrode bodies 10.

[0040] The electrode body 10 has a phase difference portion 6 including the first electrode 2. The phase difference portion 6 refers to the general term for layers having portions extending relative to the side of the second electrode 4. Figure 2 In this context, the layer consisting of the first current collector 1, the two first electrodes 2, and the two solid electrolyte layers 3 (the layer sandwiched between the solid electrolyte layers 3 from one side of the stacking direction to the other side) is collectively referred to as the phase difference section 6.

[0041] The stacked electrode body 100 (electrode body 10) has two end faces and a side face in the stacking direction. The "side face" is the face formed by the outer edge of the stacked electrode body 100 (electrode body 10). The side face where the phase difference portion 6 is provided can be any side face. Sometimes, for connection with the electrode terminal, the current collector extends from the side face. In such cases, it is preferable to provide the phase difference portion 6 on a side face different from the side face where the current collector extends. This is because, as will be described later, the side face where the phase difference portion 6 is provided is fixed with resin.

[0042] The reason for providing such a phase difference portion 6 in the electrode body 10 is to prevent short circuits caused by Li deposition. To improve the effectiveness of this effect, the first electrode 2 extends further to the side relative to the second electrode 4. More specifically, the area of ​​the first electrode 2 is designed to be larger than the area of ​​the second electrode, and the second electrode 4 is positioned closer to the inner edge of the first electrode 2. Figure 2 The reason why the first current collector 1 and the solid electrolyte layer 3 are included in the phase difference section is to match the shape of the first electrode 2.

[0043] In the phase difference section 6, the portion extending relative to the second electrode 4 is called the protruding portion. The length X of the protruding portion in the protruding direction (refer to...) Figure 2 For example, the length is in the range of 0.1 mm to 10 mm. Specifically, in the stacked electrode body 10, the length in the extension direction of the longest protruding portion is preferably in the range of 1 mm to 10 mm, more preferably in the range of 2 mm to 5 mm. The length in the extension direction of the shortest protruding portion is preferably in the range of 0.1 mm to 2 mm, more preferably in the range of 0.5 mm to 1 mm.

[0044] Next, comparisons are made between each electrode body 10. In adjacent electrode bodies 10, a gap exists between one phase difference portion 6 and another phase difference portion 6, and the lengths of the portions (extended portions) of one phase difference portion 6 and another phase difference portion 6 extending relative to the second electrode are different in the extension direction. Preferably, the second electrode 4 is of equal size in each electrode body 10.

[0045] Each electrode body 10 has a phase difference portion 6, and therefore there is a gap between their phase difference portions 6. In addition, in the stacked electrode bodies 100, the lengths of the protruding portions of the phase difference portions 6 are different between adjacent electrode bodies 10. That is, adjacent phase difference portions 6 are stepped.

[0046] Thus, the adjacent phase difference portions 6 are stepped, making it easy to coat the sides of the laminated electrode body 100 with resin. For example, it can be shaped so that resin can be coated onto the sides without tilting the electrode. In addition, the laminated electrode body 100 does not require pressurization or depressurization to coat the resin, so resin leakage to the electrode reaction surface is suppressed, and electrode misalignment when resin is coated onto the sides is also suppressed. Furthermore, by making it easy to coat the sides of the laminated electrode body with resin, the risk of short circuits caused by powder shedding from the sides of the electrode after resin fixation is suppressed.

[0047] The difference in length X in the protruding direction of the protruding portions of adjacent phase difference portions 6 is, for example, in the range of 0.01 mm to 1 mm. Preferably, it is in the range of 0.1 mm to 0.5 mm. The size of the gap between the phase difference portions 6 is determined by the configuration of the electrode body 10.

[0048] The shape of the electrode stack 100 as a whole will be described below. Figure 2 The image shows an example of an electrode stack 100 in which the length of the protruding portion of the phase difference section 6 in the protruding direction increases or decreases in stages from one side to the other in the stacking direction. Additionally, Figure 3 An example of a stacked electrode body 100' is shown in which the length of the protruding portion of the phase difference section 6 in the protruding direction increases or decreases in stages from the center to the outside in the stacking direction. However, the shape of the electrode stack 100 is not limited to these examples, as long as the lengths of the protruding portions of adjacent phase difference sections 6 in the protruding direction are different.

[0049] To explain, since the protruding portions of adjacent phase difference portions 6 of the stacked electrode body 100 have different lengths, it is considered that the positioning is poor when the battery is housed in a specified container. However, the shape can be controlled by the resin coating described later. Therefore, the positioning of the stacked electrode body 100 can be improved. For example, by coating the resin in a way that makes the shape quadrilateral, the positioning is improved (see reference). Figure 4 ).

[0050] The following describes the various elements constituting the electrode body 10.

[0051] <Collider 1, Collector 2>

[0052] One of the first current collector 1 and the second current collector 5 is a positive current collector, and the other is a negative current collector. Here, in the electrode body 10, these current collectors can be formed as a single sheet in a single layer, or multiple sheets can be stacked to form a single layer. In addition, a single current collector layer can be shared between one electrode body 10 and other electrode bodies 10.

[0053] Metal foils such as SUS, Ni, Cr, Al, Pt, Fe, Ti, and Zn can be used as the positive current collector. Alternatively, a carbon coating can be deposited on the surface of the positive current collector. The thickness of the carbon coating can range from, for example, 1 μm to 20 μm. The carbon coating material consists of carbon and a binder.

[0054] As a negative current collector, metal foils such as SUS, Cu, Ni, Fe, Ti, Co, and Zn can be used.

[0055] <Electrode 1 (2), Electrode 2 (4)>

[0056] One of the first electrode 2 and the second electrode 4 is a positive electrode, and the other is a negative electrode. Specifically, when the first current collector 1 is a negative current collector, the first electrode 2 is a negative electrode, and when the first current collector 1 is a positive current collector, the first electrode 2 is a positive electrode. Similarly, when the second current collector 5 is a negative current collector, the second electrode 4 is a negative electrode, and when the second current collector 5 is a positive current collector, the second electrode 4 is a positive electrode. From the viewpoint of preventing short circuits caused by Li deposition, it is preferable that the first electrode 2 is a negative electrode and the second electrode 4 is a positive electrode.

[0057] The positive electrode must contain at least a positive electrode active material. Examples of well-known positive electrode active materials that can be used in lithium-ion all-solid-state batteries include lithium cobalt oxide.

[0058] The positive electrode may contain a solid electrolyte, and known solid electrolytes can be used, such as oxide solid electrolytes and sulfide solid electrolytes. A sulfide solid electrolyte is preferred. Examples of sulfide solid electrolytes include Li₂S-P₂S₅. The ratio of Li₂S to P₂S₅ in Li₂S-P₂S₅ is, for example, in the range of Li₂S:P₂S₅ = 50:50 to 100:0. A ratio of 50:50 to 90:10 is preferred. The positive electrode may contain a binder. Known binders can be used, such as fluorinated resins like polyvinylidene fluoride (PVdF). The positive electrode may contain a conductive material. Known conductive materials can be used, such as acetylene black and fumed carbon fiber (VGCF).

[0059] There are no particular limitations on the thickness of the positive electrode; for example, it can be in the range of 0.1 μm to 1000 μm. The content of each component in the positive electrode can be set to be the same as before.

[0060] The negative electrode contains at least a negative electrode active material. Examples of known negative electrode active materials that can be used in lithium-ion all-solid-state batteries include graphite and other known carbon materials.

[0061] The negative electrode may contain a solid electrolyte. Examples of known solid electrolytes include, for instance, the solid electrolyte described above that can be used as the positive electrode. The negative electrode may contain a binder. Examples of known binders include, for instance, the binder described above that can be used as the positive electrode. The negative electrode may contain a conductive material. Examples of known conductive materials include, for instance, the conductive material described above that can be used as the positive electrode.

[0062] There are no particular limitations on the thickness of the negative electrode; for example, it can be in the range of 0.1 μm to 1000 μm. The content of each component in the negative electrode can be set to be the same as before.

[0063] <Solid Electrolyte Layer 3>

[0064] The solid electrolyte layer 3 contains a solid electrolyte. Examples of solid electrolytes that can be used in lithium-ion all-solid-state batteries include the solid electrolyte described above that can be used as the positive electrode.

[0065] The solid electrolyte layer 3 may contain an adhesive. Examples of known adhesives include the aforementioned adhesives suitable for the positive electrode and butadiene rubber.

[0066] The thickness of the solid electrolyte layer 3 is not particularly limited, for example, it is in the range of 0.1 μm to 1000 μm. Preferably, it is in the range of 0.1 μm to 300 μm. The content of each component in the solid electrolyte layer 3 can be set to be the same as in the past.

[0067] [Resin-fixed laminated electrode body]

[0068] The resin-fixed laminated electrode body disclosed herein is formed by fixing the side surface of the aforementioned laminated electrode body with resin. Figure 4 Resin-fixed laminated electrode bodies 200 and 200' are shown as resin-fixed laminated electrode bodies. Figure 4 The 110 in the text represents resin. The reason for fixing the sides of the stacked electrode body with resin in this way is to suppress stacking misalignment and to suppress short circuits caused by foreign matter falling off the electrode end faces.

[0069] The side surface fixed with resin can be any side surface of the stacked electrode body, but preferably at least the side surface with the phase difference portion. Alternatively, all sides can be fixed with resin. It should be noted that the gaps between the phase difference portions do not need to be filled with resin. This is because fixing only the sides of the stacked electrode body with resin is sufficient.

[0070] The resin used for fixing the laminated electrode body can be either a thermosetting resin or a photocurable resin. Photocurable resin is preferred.

[0071] [All-solid-state battery]

[0072] The all-solid-state battery of this disclosure has the above-described laminated electrode body or resin-fixed laminated electrode body. Preferably, the all-solid-state battery of this disclosure has a resin-fixed laminated electrode body. The all-solid-state battery of this disclosure may have a container for accommodating the laminated electrode body or resin-fixed laminated electrode body, other necessary terminals, etc.

[0073] [Manufacturing methods for laminated electrode bodies, resin-fixed laminated electrode bodies, and all-solid-state batteries]

[0074] The manufacturing methods of the stacked electrode body, the resin-fixed stacked electrode body, and the all-solid-state battery of the present invention will be described. Hereinafter, the manufacturing method of the all-solid-state battery will be described as a comprehensive manufacturing method thereof. The manufacturing method of the all-solid-state battery includes a preparation step, a stacking step, a cutting step, an electrode body stacking step, a resin fixing step, and a containment step.

[0075] <Preparation Process>

[0076] In the preparation process, a positive electrode, a solid electrolyte layer, and a negative electrode are prepared separately. There are no particular limitations on their fabrication methods; they can be carried out using known methods. For example, when fabricating the positive electrode, the materials constituting the positive electrode are mixed with a solvent to form a slurry. This slurry is then coated onto a substrate or the positive electrode current collector and dried to obtain the positive electrode. The solid electrolyte layer and the negative electrode can also be fabricated using the same method.

[0077] <Lamination Process>

[0078] The lamination process involves stacking a positive current collector, a positive electrode, a solid electrolyte layer, a negative electrode, and a negative current collector. In this process, for example, the negative electrode, the solid electrolyte layer, the positive electrode, and the positive current collector are stacked sequentially on both sides of the negative current collector. This is the stacking sequence in the aforementioned electrode body where the first current collector is the negative current collector, the first electrode is the negative electrode, the second current collector is the positive current collector, and the second electrode is the positive electrode. However, the stacking sequence is not limited to this; the positive electrode, the solid electrolyte layer, the negative electrode, and the negative current collector can also be stacked sequentially on both sides of the positive current collector. This is the stacking sequence in the aforementioned electrode body where the first current collector is the positive current collector, the first electrode is the positive electrode, the second current collector is the negative current collector, and the second electrode is the negative electrode. The stacking of each element can be performed using known methods.

[0079] In addition, during the lamination process, to improve the adhesion of each layer after stacking the electrode elements, the laminate can be pressed, for example, at a pressure of around 600 MPa.

[0080] <Cutting Process>

[0081] The cutting process is a process of cutting the phase difference portion of a laminate produced by the lamination process. This is to make the protruding lengths of the phase difference portions of adjacent electrode bodies different in the protruding direction. For example, as Figure 4As shown, the phase difference portion of the laminate is cut in a stepped manner from one side to the other in the stacking direction. In the laminated electrode body, the phase difference portion with the longest protruding part may not be cut in the cutting process. Each electrode body constituting the laminated electrode body is manufactured through the cutting process. For example, a known laser cutting device is preferably used for the cutting process. This is because laser cutting can suppress electrode cracking and achieve good cutting.

[0082] The reason for cutting off the phase difference portion in the cutting process is that if other parts are cut off, the energy density may decrease. That is, it can be said that by cutting off the phase difference portion in the cutting process and making the lengths of the protruding parts of adjacent phase difference portions different in the protruding direction, the decrease in energy density can be suppressed.

[0083] <Electrode stacking process>

[0084] The electrode stacking process involves layering the fabricated electrode bodies. This process creates stacked electrode bodies. There are no particular limitations on the method of stacking the electrode bodies; for example, it can be performed as follows: First, an adhesive is applied to a current collector (second current collector) positioned on the outer side of each electrode body in the stacking direction, and then the electrode bodies are stacked. Then, to improve adhesion, pressing is performed. At this time, the stacked electrode bodies can be heated and pressed. For example, the pressing pressure is 1 MPa and the temperature is approximately 140°C.

[0085] During the stacking of electrode bodies, it is checked whether any electrode bodies have shifted position. The checking method involves calculating the positive electrode center from the upper surface in the stacking direction and using this center as a reference to check for positional shifts. For example, known image inspection methods can be used for this check.

[0086] <Resin Fixation Process>

[0087] The resin fixing process is the process of fixing the sides of the fabricated laminated electrode body with resin. Through the resin fixing process, a resin-fixed laminated electrode body is fabricated. Figure 6 illustrates the resin fixing process.

[0088] First, such as Figure 6A As shown, the mold is fixed to the electrode stack to follow the thickness variation of the electrode stack. At this time, pressure is applied within a range that minimizes the gap between the electrodes and does not damage them. It should be noted that the pressure at which the mold does not deform is the upper limit when the strength of the mold is weaker than the strength of the electrodes. Regarding the mold material, any material with good demolding properties is acceptable, such as fluoropolymer. Next, as... Figure 6B As shown, resin is filled into the space on the side of the electrode stack and enclosed by the mold and the electrode stack. Then, as... Figure 6CAs shown, the remaining resin overflowing from the mold is scraped off using a scraper or similar tool, allowing the resin to cure. Heating is performed when using thermosetting resins. UV irradiation is performed when using photosetting resins. Finally, as... Figure 6D As shown, remove the mold.

[0089] <Accommodation Process>

[0090] The containment process is the process of accommodating the fabricated laminated electrode body or resin-fixed laminated electrode body into a specified container. This containment process enables the fabrication of all-solid-state batteries. It should be noted that during the containment process, terminals and other necessary components can be connected to the laminated electrode body or resin-fixed laminated electrode body.

[0091] The above describes the stacked electrode body, resin-fixed stacked electrode body, all-solid-state battery, and methods for manufacturing the same thereof. According to this disclosure, it is possible to provide a stacked electrode body that is easily coated with resin on its sides, a resin-fixed stacked electrode body using the stacked body, and an all-solid-state battery.

Claims

1. A resin-fixed laminated electrode body, wherein the sides of the laminated electrode body are fixed with resin, and at least the sides having the phase difference portion are fixed with said resin. The stacked electrode body is a stacked electrode body for all-solid-state batteries, comprising multiple electrode bodies stacked together. Each electrode body has a first electrode, a solid electrolyte layer, a second electrode, and a second current collector sequentially disposed on both sides of the first current collector. The electrode body has a phase difference portion including the first electrode. The phase difference portion extends from the side relative to the second electrode. In adjacent electrode bodies, the lengths of the portions of one phase difference portion and the portions of the other phase difference portion that extend relative to the second electrode are different in the direction of extension. The length of the portion of the phase difference relative to the second electrode in the protruding direction increases or decreases in stages from the center of the stacked electrode body toward the outside in the stacking direction.

2. An all-solid-state battery having the resin-fixed laminated electrode body as described in claim 1.

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