All-solid-state battery and method for manufacturing all-solid-state battery

Abstract

The all-solid-state battery includes a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and an insulating layer disposed along an outer peripheral portion of the positive electrode layer. The positive electrode layer has a first side provided with a positive electrode layer inclined portion. In the positive electrode layer inclined portion, the positive electrode layer is inclined such that the thickness decreases toward the outside. The insulating layer has an insulating layer sloped portion at a portion sandwiching the positive electrode layer sloped portion, and the insulating layer is sloped at the insulating layer sloped portion such that the thickness decreases in the same direction as the thickness of the positive electrode layer sloped portion.

Description

Technical Field

[0001] This invention relates to all-solid-state batteries and methods for manufacturing all-solid-state batteries. Background Technology

[0002] All-solid-state batteries are secondary batteries in which virtually all materials, including the electrolyte layer, are composed of solid materials. One challenge in all-solid-state batteries is preventing damage during pressing. In the manufacture of all-solid-state batteries, multiple layers are sometimes stacked and pressed together. During pressing, the stacked layers can sometimes be damaged.

[0003] Relatedly, Patent Document 1 (WO2020 / 022111A) discloses a technique for suppressing cracks and other defects generated during lamination and pressing. Specifically, it discloses a positive electrode for a solid-state battery, which includes a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material formed on the positive electrode current collector, wherein positive electrode guides are disposed on at least two adjacent sides of the outer periphery of the positive electrode active material layer on the surface having the positive electrode active material layer. Summary of the Invention

[0004] However, as a pressing method in the manufacture of all-solid-state batteries, the inventors are researching roll pressing. Specifically, they are researching applying pressure to the resulting laminate after placing a solid electrolyte layer on the positive electrode layer using roll pressing. However, they have discovered the following problem: the ends of the solid electrolyte layer are prone to damage when roll pressing is performed. During roll pressing, the roller rises onto the laminate at its ends. When the roller rises onto the laminate, it applies a large shear force to the solid electrolyte layer. As a result, damage such as cracks can sometimes occur in the solid electrolyte layer.

[0005] Furthermore, while there are descriptions related to lamination and pressing in Patent Document 1 (WO2020 / 022111A), there are no descriptions related to rolling.

[0006] Therefore, the object of the present invention is to provide a technique that can prevent damage to the solid electrolyte layer during rolling.

[0007] In one technical solution, the all-solid-state battery of the present invention comprises: a positive electrode layer; a solid electrolyte layer stacked on the positive electrode layer; a negative electrode layer stacked on the solid electrolyte layer; and an insulating layer disposed along the outer periphery of the positive electrode layer in contact with the outer periphery of the positive electrode layer. The positive electrode layer has a first side with a sloped portion at its end in a first direction perpendicular to the stacking direction. The first side extends along a second direction, which is perpendicular to the stacking direction and is different from the first direction. At the sloped portion of the positive electrode layer, the positive electrode layer slopes such that its thickness decreases towards the outer side. The insulating layer is disposed along the portion of the outer periphery of the positive electrode layer other than the first side. The portion of the insulating layer sandwiching the sloped portion of the positive electrode layer in the second direction has an insulating layer sloped portion. At the sloped portion of the insulating layer, the end face of the insulating layer slopes such that its thickness decreases in the same direction as the direction in which the thickness of the sloped portion of the positive electrode layer decreases. Attached Figure Description

[0008] Figure 1 This is a top view showing the all-solid-state battery of the first embodiment.

[0009] Figure 2 It means Figure 1 A diagram of section AA'.

[0010] Figure 3 It means Figure 1 A diagram of the BB' section.

[0011] Figure 4A This is a schematic cross-sectional view representing the rolling process.

[0012] Figure 4B This is a schematic cross-sectional view showing the state of solid electrolyte layers when they are stacked using transfer pressing.

[0013] Figure 5A This is a schematic cross-sectional view showing the manufacturing method of the all-solid-state battery of Reference Example 1.

[0014] Figure 5B This is a schematic cross-sectional view showing the manufacturing method of the all-solid-state battery in Reference Example 2.

[0015] Figure 5C This is a schematic cross-sectional view showing the manufacturing method of the all-solid-state battery in Reference Example 3.

[0016] Figure 6 This is a top view representing variation 1.

[0017] Figure 7A This is a schematic cross-sectional view representing variation 2.

[0018] Figure 7B This is a schematic sectional view of reference example 4.

[0019] Figure 7C This is a schematic top view of reference example 5.

[0020] Figure 8A This is a partial schematic cross-sectional view of the all-solid-state battery of Modified Example 3.

[0021] Figure 8B This is a partial schematic cross-sectional view of the all-solid-state battery in Reference Example 6.

[0022] Figure 8C This is a partial schematic cross-sectional view of the all-solid-state battery in Reference Example 7.

[0023] Figure 9A This is a schematic cross-sectional view of the all-solid-state battery in variation 4.

[0024] Figure 9B This is a partial schematic cross-sectional view of reference example 8.

[0025] Figure 10A This is a schematic cross-sectional view of the all-solid-state battery in Modified Example 5.

[0026] Figure 10B This is a partial schematic sectional view of reference example 9.

[0027] Figure 11 This is a schematic cross-sectional view of the all-solid-state battery of Modified Example 6. Detailed Implementation

[0028] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a top view showing the all-solid-state battery 1 of this embodiment. Figure 2 It means Figure 1 A diagram of section AA'. Figure 3 It means Figure 1 A diagram of the BB' section.

[0029] like Figures 1-3 As shown, the all-solid-state battery 1 has a positive electrode current collector foil 2, a positive electrode layer 3, a solid electrolyte layer 4, a negative electrode layer 5, a negative electrode current collector foil 6, and an insulating layer 7. Furthermore, in... Figure 1 For ease of observation, the diagram of the negative electrode current collector foil 6 has been omitted. Figure 2 and Figure 3 As shown, the positive electrode layer 3, solid electrolyte layer 4, negative electrode layer 5, negative electrode current collector foil 6, and insulating layer 7 are respectively disposed on both sides of the positive electrode current collector foil 2. Specifically, the positive electrode layer 3 is stacked on the positive electrode current collector foil 2. The insulating layer 7 is partially disposed on the positive electrode current collector foil 2 along the outer periphery of the positive electrode layer 3. The solid electrolyte layer 4 is stacked on the positive electrode layer 3 and the insulating layer 7. The negative electrode layer 5 is stacked on the solid electrolyte layer 4. The negative electrode current collector foil 6 is stacked on the negative electrode layer 5.

[0030] Furthermore, in this specification, "solid electrolyte layer" can refer to any layer that can be described as substantially solid in its entirety, and is not limited to a layer composed solely of solid materials. For example, a solid electrolyte layer can also be a layer containing a solid material as the main component and a small amount of liquid electrolyte.

[0031] The all-solid-state battery 1 of this embodiment is a secondary battery that is charged and discharged via lithium ions. During charging, lithium ions move from the positive electrode layer 3 to the negative electrode layer 5 via the solid electrolyte layer 4, and are absorbed by the negative electrode layer 5. On the other hand, during discharging, lithium ions move from the negative electrode layer 5 to the positive electrode layer 3, and are absorbed by the positive electrode layer 3. Furthermore, the all-solid-state battery 1 can also be a deposition-type secondary battery. A deposition-type secondary battery is one configured such that metallic lithium is deposited between the negative electrode current collector foil 6 and the solid electrolyte layer 4 during charging. In such a deposition-type secondary battery, at least the metallic lithium deposited during charging functions as the negative electrode layer 5. In the case of a deposition-type battery, a protective layer for preventing reaction between metallic lithium and the solid electrolyte layer 4 may be provided between the negative electrode layer 5 and the solid electrolyte layer 4.

[0032] In this embodiment of the all-solid-state battery 1, the structures of the positive electrode layer 3 and the insulating layer 7 are improved to prevent damage to the solid electrolyte layer 4 during rolling. This will be explained below.

[0033] like Figure 1 As shown, positive electrode layer 3 (reference) Figure 1 The oblique portion (in the image) has a first side 9 at its end in the first direction. The first direction is perpendicular to the stacking direction. The first side 9 is the side where the inclined portion 8 of the positive electrode layer is provided, and extends along the second direction. The second direction is perpendicular to the stacking direction and is a direction different from the first direction. Figure 1 In the example shown, the cathode layer 3 is rectangular when viewed along the stacking direction. Furthermore, one of the two shorter sides of the rectangle is the first side 9. That is, the second direction is perpendicular to the first direction. However, the second direction does not necessarily have to be perpendicular to the first direction; it can also be a direction that extends obliquely relative to the first direction. For example, the cathode layer 3 can also be a shape other than a rectangle (e.g., a parallelogram).

[0034] The inclined portion 8 of the positive electrode layer is the inclined part of the positive electrode layer 3. That is, as shown in the figure... Figure 2 As shown, at the inclined portion 8 of the positive electrode layer, the positive electrode layer 3 is inclined such that its thickness decreases as it moves outward. Because the inclined portion 8 of the positive electrode layer is provided, as will be described later, damage to the solid electrolyte layer 4 during rolling can be prevented.

[0035] On the other hand, the insulating layer 7 is arranged along the outer periphery of the positive electrode layer 3, excluding the first side 9 (the three sides excluding the first side 9) (see reference). Figure 1(The diagonal section in the middle). No insulating layer 7 is provided on the outer side of the first side 9. The insulating layer 7 is provided to protect the solid electrolyte layer 4 on the end of the positive electrode layer 3 and is in contact with the outer periphery of the positive electrode layer 3.

[0036] The insulating layer 7, like the positive electrode layer 3, is locally tilted. Specifically, as... Figure 1 As shown, an insulating layer inclined portion 12 is provided in the portion of the insulating layer 7 that sandwiches the positive electrode layer inclined portion 8 in the second direction. At the insulating layer inclined portion 12, the insulating layer 7 is inclined in the same direction as the thickness of the positive electrode layer inclined portion 8. That is, in the region along the extension line of the positive electrode layer inclined portion 8 in the second direction, the insulating layer 7 is inclined in the same way as the positive electrode layer 3. The insulating layer inclined portion 12, like the positive electrode layer inclined portion 8, is also provided to prevent damage to the solid electrolyte layer 4 during rolling.

[0037] The above is a general structure of the all-solid-state battery 1. According to this embodiment, the all-solid-state battery 1, due to the presence of a positive electrode layer inclined portion 8 and an insulating layer inclined portion 12 (hereinafter, both are sometimes collectively referred to as "inclined portions"), can prevent damage to the solid electrolyte layer 4 during rolling. This will be explained below based on the manufacturing method of the all-solid-state battery 1.

[0038] In manufacturing the all-solid-state battery 1, a positive electrode current collector foil 2 is first prepared. Then, a positive electrode layer 3 and an insulating layer 7 are stacked on both sides of the positive electrode current collector foil 2.

[0039] For example, a slurry containing the constituent material of the positive electrode layer 3 is prepared, the prepared slurry is coated onto the positive electrode current collector foil 2, and then dried. This forms the positive electrode layer 3. At this time, by controlling the amount of slurry coated at the ends, a tilted portion 8 of the positive electrode layer can be formed. The insulating layer 7 can also be formed using the same method as the positive electrode layer 3. That is, a slurry containing the constituent material of the insulating layer 7 is prepared, the prepared slurry is coated onto the positive electrode current collector foil 2, and then dried. This forms the insulating layer 7. At this time, by controlling the amount of slurry coated at the ends, a tilted portion 12 of the insulating layer can be formed. After laminating the positive electrode layer 3 and the insulating layer 7, rolling can also be performed as needed.

[0040] Next, a solid electrolyte layer 4 is stacked on the positive electrode layer 3 and the insulating layer 7.

[0041] For example, a slurry containing the constituent materials of the solid electrolyte layer 4 is prepared, and the prepared slurry is coated onto the positive electrode layer 3 and the insulating layer 7. Then, the slurry is dried as needed. Thus, the solid electrolyte layer 4 is formed. After the solid electrolyte layer 4 is formed, it is rolled. Using rolling, pressure is applied to the solid electrolyte layer 4 towards the positive electrode layer 3. Figure 4AThis is a schematic cross-sectional view showing the rolling process. During rolling, with the first side 9 of the positive electrode layer 3 as the upstream side, the roller 13 moves along the first direction on the solid electrolyte layer 4. As a result, the solid electrolyte layer 4 is pressurized towards the positive electrode layer 3. Furthermore, the rolling is preferably performed by a device capable of controlling the linear pressure.

[0042] The solid electrolyte layer 4 can also be laminated using transfer pressing instead of coating. Figure 4B This is a schematic cross-sectional view showing the state of the laminate when the solid electrolyte layer 4 is laminated using transfer pressing. Furthermore, in Figure 4B The diagram shows only the structure of one side of the positive electrode current collector foil 2. In this example, a solid electrolyte layer 4 pre-coated on a transfer sheet 14 is placed on the positive electrode layer 3 and the insulating layer 7. Then, a roller 13 presses the solid electrolyte layer 4 from the transfer sheet 14 toward the positive electrode layer 3. Thus, the solid electrolyte layer 4 is bonded to the positive electrode layer 3. That is, rolling is performed simultaneously with the placement of the solid electrolyte layer 4. In this case, the roller 13 also moves along the first direction on the transfer sheet 14 with the first side 9 as the upstream side. Afterward, the transfer sheet 14 is peeled off at an appropriate time.

[0043] In this embodiment, the inclined portion prevents damage to the solid electrolyte layer 4 during rolling. This will be explained below in comparison with a reference example.

[0044] Figure 5A This is a schematic cross-sectional view illustrating the manufacturing method of the all-solid-state battery according to Reference Example 1. In Reference Example 1, no inclined section is provided. Therefore, a step is formed at the end of the positive electrode layer 3. Although not shown, a step is also formed in the insulating layer 7. In Reference Example 1, a large shear force is applied to the solid electrolyte layer 4 when the roller 13 crosses the step. Therefore, damage such as cracks is easily generated in the solid electrolyte layer 4. In contrast, in this embodiment, a large step is not formed at the end of the positive electrode layer 3. Since the roller 13 climbs up the positive electrode layer 3 along the inclined section, such a large shear force is not applied to the solid electrolyte layer 4. Therefore, damage to the solid electrolyte layer 4 can be prevented.

[0045] Figure 5B This is a schematic cross-sectional view illustrating a method for manufacturing an all-solid-state battery according to Reference Example 2. In Reference Example 2, an insulating layer 7 is also provided on the portion of the outer periphery of the positive electrode layer 3 that becomes the upstream side during rolling. In Reference Example 2, during rolling, sometimes a portion of the insulating layer 7 may climb onto the positive electrode layer 3. In the portion where the insulating layer 7 climbs, a large shear force may be applied to the solid electrolyte layer 4, sometimes causing damage to the solid electrolyte layer 4. In contrast, in this embodiment, the insulating layer 7 does not climb onto the positive electrode layer 3, therefore the solid electrolyte layer 4 is less likely to be damaged.

[0046] Figure 5CThis is a schematic cross-sectional view illustrating the manufacturing method of the all-solid-state battery according to Reference Example 3. In Reference Example 3, similar to Reference Example 2, an insulating layer 7 is also provided on the portion of the outer periphery of the positive electrode layer 3 that becomes the upstream side during rolling. However, a gap exists between the positive electrode layer 3 and the insulating layer 7. In Reference Example 3, a large shear force is applied to the solid electrolyte layer 4 in the gap portion. Therefore, damage to the solid electrolyte layer 4 is easily caused. In contrast, in this embodiment, since such a gap does not exist, damage to the solid electrolyte layer 4 can be prevented.

[0047] As explained above, according to this embodiment, since the inclined portion is provided, the shear force applied to the solid electrolyte layer 4 during rolling can be reduced, and damage to the solid electrolyte layer 4 can be prevented.

[0048] Furthermore, the width of the inclined portion 8 in the first direction is preferably determined based on the diameter of the roller 13. When the roller diameter is small, the width of the inclined portion can be shortened.

[0049] Furthermore, the tilt angle of the positive electrode layer tilted portion 8 (the angle between the upper surface of the positive electrode layer 3 and the surface of the positive electrode current collector foil 2) can be set according to the susceptibility of the solid electrolyte layer 4 to damage during rolling. Preferably, the tilt angle of the tilted portion is 45° or less. More preferably, the tilt angle is 30° or less. The tilt angle of the insulating layer tilted portion 12 is the same.

[0050] After the solid electrolyte layer 4 is stacked, the negative electrode layer 5 and the negative electrode current collector foil 6 are further stacked. There are no particular limitations on the stacking method of the negative electrode layer 5 and the negative electrode current collector foil 6. For example, a negative electrode current collector foil 6 with a negative electrode layer 5 stacked on it can be prepared in advance and then stacked on the solid electrolyte layer 4. Then, a stacking pressing process is performed. Thus, the negative electrode layer 5 and the negative electrode current collector foil 6 can be stacked on the solid electrolyte layer 4. Furthermore, in the case where the all-solid-state battery 1 is of the deposition type, it is not necessarily necessary to provide the negative electrode layer 5 during the manufacturing stage. For example, a negative electrode current collector foil 6 with a protective layer instead of a negative electrode layer 5 can be prepared and stacked on the solid electrolyte layer 4.

[0051] (Variation Example 1)

[0052] Next, a variation of this embodiment will be described. Figure 6This is a top view showing Modification Example 1. This modification example relates to the configuration of the inclined portions. In this modification example, inclined portions are provided at both ends in the first direction. That is, a first side 9-1 is provided at one end of the positive electrode layer 3 in the first direction, and a first side 9-2 is provided at the other end of the positive electrode layer 3 in the first direction. Furthermore, a positive electrode layer inclined portion 8-1 is provided along the first side 9-1, and a positive electrode layer inclined portion 8-2 is provided along the first side 9-2. Similarly, for the insulating layer 7, inclined portions 12 are provided at both ends in the first direction. That is, an insulating layer inclined portion 12-1 is provided at a position sandwiching the positive electrode layer inclined portion 8-1 in the second direction, and an insulating layer inclined portion 12-2 is provided at a position sandwiching the positive electrode layer inclined portion 8-2 in the second direction. In addition, the insulating layer 7 is provided along the two long sides of the outer periphery of the positive electrode layer 3, and not on the short sides (first side 9-1 and first side 9-2).

[0053] According to this modified example, since an inclined portion is also provided on the downstream side, the shear force applied to the solid electrolyte layer 4 during rolling can also be suppressed at the downstream end of the positive electrode layer 3. Furthermore, in this modified example, the insulating layer 7 has a straight shape along the first direction. Therefore, when forming the insulating layer 7, the slurry can be applied in a straight line. Because the shape of the insulating layer 7 is simple, it can be easily manufactured.

[0054] (Variation Example 2)

[0055] Next, we will explain variation example 2. Figure 7A This is a schematic cross-sectional view showing Modified Example 2. This modified example is related to the shape of the inclined portion 8 of the positive electrode layer. In this modified example, the thickness of the positive electrode layer 3 at the top end (i.e., the first side 9) of the inclined portion 8 of the positive electrode layer is defined. Details are described below.

[0056] like Figure 7A As shown, the region of the positive electrode layer 3 excluding the inclined portion 8 is defined as the flat portion 15. The thickness of the positive electrode layer 3 at the flat portion 15 is defined as t1. The thickness of the solid electrolyte layer 4 in the region overlapping with the flat portion 15 is defined as t2. The thickness of the top of the inclined portion 8 is defined as tx. Here, t1 is greater than t2. On the other hand, tx is less than or equal to t2.

[0057] According to this modified example, damage to the solid electrolyte layer 4 can be prevented more reliably without reducing the output density, etc. This will be explained below with reference to the reference example.

[0058] Figure 7BThis is a schematic cross-sectional view of Reference Example 4. In this reference example, t2 is greater than t1. That is, the thickness of the solid electrolyte layer 4 is greater. In this case, since the solid electrolyte layer 4 is thicker, its strength can be increased, and perhaps the shear force can be reduced, but the output density and energy density will decrease. In contrast, according to Figure 7A In the modified example 2 shown, since t2 is less than t1, damage to the solid electrolyte layer 4 can be prevented without reducing the output density and energy density.

[0059] Figure 7C This is a schematic top view of Reference Example 5. In this reference example, tx is greater than t2. That is, the thickness of the top of the inclined portion 8 of the positive electrode layer (the thickness of the top portion of the positive electrode layer 3) is relatively large. In this example, a relatively high step is formed at the end of the positive electrode layer 3, so a large shear force is easily applied to the solid electrolyte layer 4 during rolling. In contrast, according to Modified Example 2 (refer to...) Figure 7A Since tx is below t2, no large step is generated at the end of the positive electrode layer 3. Therefore, the shear force applied to the solid electrolyte layer 4 can be sufficiently reduced, and damage to the solid electrolyte layer 4 can be prevented more reliably.

[0060] In addition, Figure 7A In the example shown, the width a (width in the first direction) of the portion of the positive electrode layer 3 formed at the top of the inclined portion 8 of the positive electrode layer, where the thickness t2 is less than or equal to the thickness (i.e., t2) of the solid electrolyte layer 4, is preferably 5 μm or more, and more preferably 10 μm or more. With such a structure, damage to the solid electrolyte layer 4 can be prevented more reliably.

[0061] (Variation Example 3)

[0062] Next, we will explain variation example 3. Figure 8A This is a partial schematic cross-sectional view of the all-solid-state battery 1 of Modified Example 3. In this modified example, the thicknesses of the positive electrode layer 3 and the insulating layer 7 are defined.

[0063] In this modified example, similarly to Modified Example 2, the thickness of the flat portion 15 of the positive electrode layer 3 is defined as t1. Furthermore, the thickness of the solid electrolyte layer 4 in the region overlapping with the flat portion 15 is defined as t2. Additionally, the thickness of the portion of the insulating layer 7 excluding the inclined portion 12 (hereinafter referred to as the flat portion 16 of the insulating layer) is defined as t3. Here, in this modified example, the difference h1 between t1 and t3 is less than or equal to t2. In short, in this modified example, the difference h1 between the thickness of the positive electrode layer 3 and the thickness of the insulating layer 7 is relatively small in the flat portion (excluding the inclined portion).

[0064] According to this modified example, the shear force applied to the solid electrolyte layer 4 at the interface between the insulating layer 7 and the positive electrode layer 3 during rolling can be reduced. Therefore, damage to the solid electrolyte layer 4 and exposure of the positive electrode layer 3 can be suppressed. This will be explained below with reference to a reference example.

[0065] Figure 8B This is a partial schematic cross-sectional view of the all-solid-state battery of Reference Example 6. This reference example demonstrates the case where the solid electrolyte layer 4 is laminated using transfer pressing, and the thickness difference h1 is greater than t2. In this reference example, because the thickness difference h1 is greater than t2, a large step is created between the insulating layer 7 and the positive electrode layer 3. Therefore, during rolling, a large shear force is applied to the solid electrolyte layer 4 at the interface between the insulating layer 7 and the positive electrode layer 3. Consequently, the solid electrolyte layer 4 is easily damaged. In contrast, in… Figure 8A In the modified example 3 shown, since no large step is generated between the insulating layer 7 and the positive electrode layer 3, damage to the solid electrolyte layer 4 can be prevented.

[0066] Figure 8C This is a partial schematic cross-sectional view of the all-solid-state battery of Reference Example 7. Reference Example 7 is an example of forming the solid electrolyte layer 4 using coating. In Reference Example 7, similar to Reference Example 6, the thickness difference h1 is greater than the thickness t2. In this reference example, because a large step is formed between the insulating layer 7 and the positive electrode layer 3, the positive electrode layer 3 is sometimes exposed at the step portion when the constituent material of the solid electrolyte layer 4 is coated. Furthermore, during rolling, the thinner layer (in the insulating layer 7 and the positive electrode layer 3)... Figure 8C On the insulating layer 7), the pressing pressure is relatively low. Therefore, it is difficult to firmly bond the solid electrolyte layer 4 to the substrate layer. In contrast, according to... Figure 8A In the modified example 3 shown, since no large steps are generated, the positive electrode layer 3 is difficult to expose even when a solid electrolyte layer 4 is formed by coating. In addition, it is also difficult for localized drops in pressing pressure to occur.

[0067] Furthermore, it is preferable that the positive electrode layer 3 and the insulating layer 7 are designed to have substantially the same thickness after rolling. However, there are also cases where it is difficult to make the positive electrode layer 3 and the insulating layer 7 have exactly the same thickness due to manufacturing reasons. In such cases, it is preferable that the positive electrode layer 3 is thicker than the insulating layer 7. If the positive electrode layer 3 is thicker than the insulating layer 7, sufficient pressure can be applied to the solid electrolyte layer 4 in the region of the positive electrode layer 3 during rolling. Therefore, the solid electrolyte layer 4 can be firmly bonded to the positive electrode layer 3. By firmly bonding the solid electrolyte layer 4 to the positive electrode layer 3, it is easy to perform its full function as a secondary battery.

[0068] (Variation Example 4)

[0069] Next, we will explain variation example 4. Figure 9A This is a schematic cross-sectional view of the all-solid-state battery 1 according to Modification Example 4. In this modification, the positional relationship in a second direction between the end of the insulating layer 7 and the end of the positive electrode current collector foil 2 is defined. Specifically, in the second direction, the end of the insulating layer 7 is located at approximately the same position as the end of the positive electrode current collector foil 2.

[0070] If the end of the insulating layer 7 and the end of the positive electrode current collector foil 2 are located at approximately the same position, it is possible to prevent the positive electrode current collector foil 2 from contacting the negative electrode current collector foil 6. Figure 9B This is a partial schematic cross-sectional view of Reference Example 8. In this reference example, the end of the insulating layer 7 is located inside the end of the positive electrode current collector foil 2. In this case, after rolling, the positive electrode current collector foil 2 may sometimes come into contact with the negative electrode current collector foil 6, resulting in a short circuit between the positive and negative electrodes. In contrast, in Modification Example 4, since the insulating layer 7 prevents contact between the positive electrode current collector foil 2 and the negative electrode current collector foil 6, a short circuit can be prevented. Furthermore, assuming that the end of the insulating layer 7 is located outside the end of the positive electrode current collector foil 2, a large load will be applied to the end of the insulating layer 7 during rolling, making the insulating layer 7 prone to damage. In contrast, in this modification example, since the end of the insulating layer 7 is aligned with the end of the positive electrode layer 3, the insulating layer 7 will not be damaged during rolling.

[0071] Furthermore, in this modified example, the fact that the ends of the insulating layer 7 and the positive electrode current collector foil 2 are located in "approximately the same position" means that slight deviations, such as manufacturing errors, are possible between them. Specifically, if the distance (deviation) in the second direction between the ends of the insulating layer 7 and the ends of the positive electrode current collector foil 2 is less than 10% of the width of the positive electrode current collector foil 2 in the second direction, it can be said to be in "approximately the same position". Preferably, the distance in the second direction between the ends of the insulating layer 7 and the ends of the positive electrode current collector foil 2 is less than 1% of the width of the positive electrode current collector foil 2.

[0072] (Variation Example 5)

[0073] Next, we will explain variation 5. Figure 10A This is a schematic cross-sectional view of the all-solid-state battery 1 of Modified Example 5. In this modified example, in the first direction, the end of the solid electrolyte layer 4 is located outside the end (first side 9) of the positive electrode layer 3.

[0074] With this structure, short circuits through the ends of the solid electrolyte layer 4 can be prevented. This is illustrated with reference to Example 9. Figure 10BThis is a partial schematic cross-sectional view of Reference Example 9. In this reference example, in the first direction, the end of the solid electrolyte layer 4 is located at approximately the same position as the end (first side 9) of the positive electrode layer 3. In this case, a short circuit may occur due to the growth of lithium dendrites bypassing the solid electrolyte layer 4 on the outside, or contact between the positive electrode current collector foil 2 and the negative electrode current collector foil 6 on the outside of the solid electrolyte layer 4. In contrast, in Figure 10A In the modified example 5 shown, since the end of the solid electrolyte layer 4 is located on the outer side of the end of the positive electrode layer 3, short circuits can be prevented.

[0075] (Variation Example 6)

[0076] Next, we will explain variation example 6. Figure 11 This is a schematic cross-sectional view of the all-solid-state battery 1 according to this modified example. In this modified example, the Young's modulus (εi) of the insulating layer 7 is smaller than the Young's modulus (εp) of the positive electrode layer 3. The Young's modulus (εi) of the insulating layer 7 is preferably 99% or less, more preferably 97% or less, of the Young's modulus (εp) of the positive electrode layer 3. Assuming that the Young's modulus (εi) of the insulating layer 7 is greater than or equal to the Young's modulus (εp) of the positive electrode layer 3, gaps are easily generated between the positive electrode layer 3 and the insulating layer 7. In addition, during rolling, due to the interference of the insulating layer 7, it is difficult to apply sufficient pressure to the solid electrolyte layer 4 on the positive electrode layer 3. As a result, the solid electrolyte layer 4 is difficult to bond to the positive electrode layer 3. Furthermore, since the solid electrolyte layer 4 is in a loose state, lithium dendrites are prone to grow in a manner that penetrates through the interior of the solid electrolyte layer 4, which easily leads to short circuits. In contrast, according to this modified example, since the Young's modulus (εi) of the insulating layer 7 is smaller than that of the positive electrode layer 3 (εp), the gap between the positive electrode layer 3 and the insulating layer 7 can be easily eliminated during rolling. Furthermore, during rolling, sufficient pressure can be applied to the solid electrolyte layer 4 in the region of the positive electrode layer 3. This allows the solid electrolyte layer 4 to be firmly bonded to the positive electrode layer 3. Moreover, since the solid electrolyte layer 4 is in a dense state, it is difficult for lithium dendrites to form penetrating the solid electrolyte layer 4, thus easily preventing short circuits.

[0077] The structure of the all-solid-state battery 1 has been described above using embodiments and variations thereof. Next, the constituent materials of each component included in the all-solid-state battery 1 will be described.

[0078] (Positive electrode layer)

[0079] The positive electrode layer 3 can be formed of a material capable of releasing lithium ions during charging and absorbing lithium ions during discharging. For example, the positive electrode layer 3 can be formed of a material comprising a resin binder and a positive electrode active material dispersed in the resin binder. As the positive electrode active material, lithium metal composite oxides can be used, for example. Examples of lithium metal composite oxides include layered rock salt compounds such as LiCoO2, LiMnO2, LiNiO2, LiVO2, and Li(Ni-Mn-Co)O2, as well as LiMn2O4 and LiNi... 0.5 Mn 1.5 Spinel-type compounds such as O4, olivine-type compounds such as LiFePO4 and LiMnPO4, or Si-containing compounds such as Li2FeSiO4 and Li2MnSiO4 can also be used. Additionally, Li4Ti5O12 can also be used.

[0080] The thickness of the positive electrode layer 3 is not particularly limited, but it is, for example, 10 to 500 μm, preferably 50 to 200 μm.

[0081] (Negative electrode layer)

[0082] The negative electrode layer 5 can be any layer configured to absorb lithium (or deposit lithium) during charging and release lithium ions during discharging. For example, the negative electrode layer 5 can be formed from a material containing a resin binder and a negative electrode active material dispersed in the resin binder. Examples of negative electrode active materials that can be used include lithium metal, silicon materials (organosilicon), tin materials, compounds containing silicon and tin (oxides, nitrides, alloys formed with other metals), and carbon materials (graphite, etc.). Furthermore, as described above, the negative electrode layer 5 can also be formed by the deposition of metallic lithium between the solid electrolyte layer 4 and the negative electrode current collector foil 6 during charging.

[0083] (Solid electrolyte layer)

[0084] The solid electrolyte layer 4 only needs to be solid and function as the electrolyte layer in the secondary battery; its material is not particularly limited. For example, the solid electrolyte layer 4 can be implemented as a layer containing solid electrolyte materials such as sulfide solid electrolyte materials and / or oxide solid electrolyte materials. Examples of sulfide solid electrolytes include LPS-based (e.g., silver sulfide germanium ore (Li6PS5Cl)) and LGPS-based (e.g., Li 10 GeP2S 12 The solid electrolyte material can also be dispersed in a resin binder. That is, the solid electrolyte layer 4 can also contain a resin binder and a solid electrolyte material dispersed in the resin binder.

[0085] The thickness of the solid electrolyte layer 4 is not particularly limited, but it is, for example, 5 to 100 μm, preferably 20 to 60 μm.

[0086] (Insulation layer)

[0087] The constituent material of the insulating layer 7 is not particularly limited as long as it is insulating. The insulating layer 7 can be formed from, for example, insulating polymers, ion-conducting polymers, insulating inorganic materials, oxide-based solid electrolytes, and sulfide-based solid electrolytes. Preferably, the insulating layer 7 has a resin binder and a solid material dispersed in the resin binder. In this case, by adjusting the content of the resin binder and the solid material, the physical properties of the insulating layer 7, such as the Young's modulus, can be controlled to the desired value. More preferably, the solid electrolyte material used in the solid electrolyte layer 4 can be used as the solid material. The solid electrolyte material is the material used to prepare the solid electrolyte layer 4. Therefore, if a solid electrolyte material is used, the Young's modulus of the insulating layer 7 can be adjusted without preparing a separate solid material for forming the insulating layer 7. Furthermore, the solid electrolyte material is less likely to cause degradation of other components within the all-solid-state battery 1. Moreover, when using a solid electrolyte material as the solid material, a material that is difficult to react with the solid electrolyte material, such as SBR, is preferably used as the resin binder.

[0088] (Positive electrode current collector foil)

[0089] For example, a metal foil can be used as the positive electrode current collector foil 2. For example, aluminum foil can be used as the positive electrode current collector foil 2.

[0090] (Negative electrode current collector foil)

[0091] The negative electrode current collector foil 6 can also be made of metal foil, for example. Copper, copper alloys, nickel and nickel alloys can be used as the negative electrode current collector foil 6.

[0092] The present invention has been described above with examples of embodiments and modifications. Furthermore, the above-described embodiments and modifications are not independent of each other and can be combined with each other without contradiction.

[0093] The following is a summary of the representative structures and effects of the present invention.

[0094] (Note 1)

[0095] The all-solid-state battery of Appendix 1 comprises: a positive electrode layer 3; a solid electrolyte layer 4 stacked on the positive electrode layer; a negative electrode layer 5 stacked on the solid electrolyte layer 4; and an insulating layer 7 disposed along the outer periphery of the positive electrode layer 3 in contact with the outer periphery of the positive electrode layer 3. The positive electrode layer 3 has a first side 9 with a positive electrode layer inclined portion 8 at its end in a first direction perpendicular to the stacking direction. The first side 9 extends along a second direction, which is perpendicular to the stacking direction and is different from the first direction. At the positive electrode layer inclined portion 8, the positive electrode layer 3 is inclined such that its thickness decreases towards the outer side. The insulating layer 7 is disposed along the portion of the outer periphery of the positive electrode layer 3 excluding the first side 9. The portion of the insulating layer 7 sandwiching the positive electrode layer inclined portion 8 in the second direction has an insulating layer inclined portion 12. At the insulating layer inclined portion 12, the insulating layer 7 is inclined such that its thickness decreases in the same direction as the thickness decreasing direction of the positive electrode layer inclined portion 8. According to this structure, since the positive electrode layer inclined portion 8 and the insulating layer inclined portion 12 are provided, the shear force applied to the solid electrolyte layer 4 at the end of the positive electrode layer 3 during rolling can be reduced. As a result, damage to the solid electrolyte layer 4 can be prevented.

[0096] (Note 2)

[0097] In the all-solid-state battery 1 described in Appendix 1, the first side 9 is only provided at one end in the first direction of the positive electrode layer. With this structure, by rolling with the first side 9 as the upstream side, it is possible to roll while preventing damage to the solid electrolyte layer 4.

[0098] (Note 3)

[0099] In the all-solid-state battery 1 described in Appendix 1, the first side 9 is provided at both ends of the positive electrode layer 3 in the first direction. With this structure, damage to the solid electrolyte layer 4 during rolling can be prevented not only on the upstream side but also at the downstream end.

[0100] (Note 4)

[0101] In the all-solid-state battery 1 described in any of Appendices 1 to 3, the thickness t1 of the portion of the positive electrode layer 3 excluding the inclined portion 8, i.e., the flat portion 15 of the positive electrode layer, is greater than the thickness t2 of the solid electrolyte layer 4 in the region overlapping with the flat portion 15 of the positive electrode layer. The thickness tx at the top of the inclined portion 8 of the positive electrode layer is less than or equal to t2. With this structure, since no large step is generated at the end of the positive electrode layer 3, damage to the solid electrolyte layer 4 during rolling can be prevented more reliably.

[0102] (Note 5)

[0103] In the all-solid-state battery 1 described in any of Appendices 1 to 4, the thickness of the positive electrode layer 3, excluding the inclined portion 8 of the positive electrode layer (i.e., the flat portion 15 of the positive electrode layer), is t1. The thickness of the solid electrolyte layer 4 in the region overlapping with the flat portion 15 of the positive electrode layer is t2. The thickness of the insulating layer 7, excluding the inclined portion of the insulating layer (i.e., the flat portion of the insulating layer), is t3. The difference h1 between thickness t1 and thickness t3 is less than or equal to thickness t2. With this structure, since no large step is generated at the interface between the positive electrode layer 3 and the insulating layer 7, it is possible to prevent large shear forces from being applied to the solid electrolyte layer 4. Therefore, damage to the solid electrolyte layer 4 can be prevented more reliably.

[0104] (Note 6)

[0105] In any one of Appendices 1 to 5, the all-solid-state battery 1 further includes a positive electrode current collector foil 2. A positive electrode layer 3 is disposed on the positive electrode current collector foil 2. When viewed along the stacking direction, in the second direction, the end of the insulating layer 7 is located at approximately the same position as the end of the positive electrode current collector foil 2. With this structure, it is possible to prevent the positive electrode current collector foil 2 from contacting the negative electrode current collector foil 6 on the outside of the insulating layer 7.

[0106] (Note 7)

[0107] In any one of Appendices 1 to 6, in the all-solid-state battery 1, when viewed along the stacking direction, in the first direction, the end of the solid electrolyte layer 4 is located further outward than the first side 9 of the positive electrode layer. With this structure, short circuits between the positive and negative electrodes at the end or outside of the solid electrolyte layer 4 can be prevented.

[0108] (Note 8)

[0109] In the all-solid-state battery 1 according to any one of Appendices 1 to 7, the Young's modulus of the insulating layer 7 is smaller than that of the positive electrode layer 3. With this structure, sufficient pressure can be applied to the solid electrolyte layer 4 in the region on the positive electrode layer 3 during rolling. This allows the solid electrolyte layer 4 to be firmly bonded to the positive electrode layer 3. Furthermore, the solid electrolyte layer 4 can be compressed into a dense state. As a result, short circuits caused by lithium dendrites penetrating the solid electrolyte layer 4 are easily prevented.

[0110] (Note 9)

[0111] In the all-solid-state battery 1 described in any one of Appendices 1 to 8, the insulating layer 7 comprises a resin binder and a solid material dispersed in the resin binder. Based on this structure, the physical properties of the insulating layer 7, such as Young's modulus, can be controlled by adjusting the content of the solid material.

[0112] (Postscript 10)

[0113] The manufacturing method of the all-solid-state battery in Appendix 10 includes: a step of stacking a positive electrode layer 3 and an insulating layer 7 on a positive electrode current collector foil 2, wherein the insulating layer 7 is disposed along the outer periphery of the positive electrode layer 3 in contact with the outer periphery of the positive electrode layer 3; a step of disposing a solid electrolyte layer 4 on the positive electrode layer 3 and the insulating layer 7; and a step of pressing the solid electrolyte layer 4 toward the positive electrode layer 3 side by means of a rolling press during or after the step of disposing the solid electrolyte layer 4. The positive electrode layer 3 has a first side 9 with a positive electrode layer inclined portion 8 at its end in a first direction perpendicular to the stacking direction. The first side 9 extends along a second direction, which is a direction perpendicular to the stacking direction and different from the first direction. At the positive electrode layer inclined portion 8, the positive electrode layer 3 is inclined such that its thickness decreases as it moves outward. The insulating layer 7 is disposed along the portion of the outer periphery of the positive electrode layer 3 excluding the first side 9. The insulating layer 7 has an inclined portion 12 in the second direction, which sandwiches the inclined portion 8 of the positive electrode layer. At the inclined portion 12, the insulating layer 7 is inclined such that its thickness decreases in the same direction as the thickness of the inclined portion 8 of the positive electrode layer. The pressing process includes a rolling process along the first direction with the first side 9 as the upstream side. According to this method, during rolling, the roller climbs along the inclined portion 8 of the positive electrode layer and the inclined portion 12 of the insulating layer onto the positive electrode layer 3. Since the roller climbs along the inclined portion, the shear force applied to the solid electrolyte layer 4 can be reduced. Therefore, damage to the solid electrolyte layer 4 can be prevented.

Claims

1. An all-solid-state battery, wherein, This all-solid-state battery has the following features: Positive electrode layer; A solid electrolyte layer is stacked on the positive electrode layer; A negative electrode layer, which is stacked on the solid electrolyte layer; and An insulating layer is disposed along the outer periphery of the positive electrode layer in contact with the outer periphery of the positive electrode layer. The positive electrode layer has a first side with an inclined portion at its end in a first direction perpendicular to the stacking direction. The first side extends along a second direction, which is perpendicular to the stacking direction and different from the first direction. At the inclined portion of the positive electrode layer, the thickness decreases as it moves outward. The insulating layer is disposed along the portion of the outer periphery of the positive electrode layer, excluding the first side. The portion of the insulating layer sandwiching the inclined portion of the positive electrode layer in the second direction has an inclined portion of the insulating layer. At the inclined portion of the insulating layer, the insulating layer is inclined in such a way that its thickness decreases in the same direction as the thickness of the inclined portion of the positive electrode layer.

2. The all-solid-state battery according to claim 1, wherein, The first side is located at only one end of the positive electrode layer in the first direction.

3. The all-solid-state battery according to claim 1, wherein, The first side is located at both ends of the positive electrode layer in the first direction.

4. The all-solid-state battery according to claim 1 or 2, wherein, The thickness t1 of the portion of the positive electrode layer excluding the inclined portion, i.e., the flat portion of the positive electrode layer, is greater than the thickness t2 of the solid electrolyte layer in the region overlapping with the flat portion of the positive electrode layer. The thickness tx at the top of the inclined portion of the positive electrode layer is less than t2.

5. The all-solid-state battery according to claim 1 or 2, wherein, The thickness of the portion of the positive electrode layer excluding the inclined portion, i.e., the flat portion, is t1. The thickness of the solid electrolyte layer in the region overlapping with the flat portion of the positive electrode layer is t2. The thickness of the portion of the insulating layer excluding the inclined portion, i.e., the flat portion, is t3. The difference h1 between thickness t1 and thickness t3 is less than or equal to thickness t2.

6. The all-solid-state battery according to claim 1 or 2, wherein, This all-solid-state battery also features a positive electrode current collector foil. The positive electrode layer is disposed on the positive electrode current collector foil. When viewed along the stacking direction, in the second direction, the end of the insulating layer is located at approximately the same position as the end of the positive current collector foil.

7. The all-solid-state battery according to claim 1 or 2, wherein, When viewed along the stacking direction, in the first direction, the end of the solid electrolyte layer is located outside the first side of the positive electrode layer.

8. The all-solid-state battery according to claim 1 or 2, wherein, The Young's modulus of the insulating layer is smaller than that of the positive electrode layer.

9. The all-solid-state battery according to claim 1 or 2, wherein, The insulating layer has a resin binder and a solid material dispersed in the resin binder.

10. A method for manufacturing an all-solid-state battery, wherein, The manufacturing method of this all-solid-state battery includes: In the process of stacking a positive electrode layer and an insulating layer on a positive electrode current collector foil, the insulating layer is disposed along the outer periphery of the positive electrode layer in such a way that it contacts the outer periphery of the positive electrode layer; The process of depositing a solid electrolyte layer on the positive electrode layer and the insulating layer; and The process of applying pressure to the solid electrolyte layer towards the positive electrode layer using a rolling press during or after the process of configuring the solid electrolyte layer. The positive electrode layer has a first side with an inclined portion at its end in a first direction perpendicular to the stacking direction. The first side extends along a second direction, which is perpendicular to the stacking direction and different from the first direction. At the inclined portion of the positive electrode layer, the thickness decreases as it moves outward. The insulating layer is disposed along the portion of the outer periphery of the positive electrode layer, excluding the first side. The portion of the insulating layer sandwiching the inclined portion of the positive electrode layer in the second direction has an inclined portion of the insulating layer. At the inclined portion of the insulating layer, the insulating layer is inclined in a direction that decreases in thickness in the same direction as the thickness decreases at the inclined portion of the positive electrode layer. The pressurizing process includes a process of rolling along the first direction with the first side as the upstream side.

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