Method for manufacturing electrolyte sheet, method for manufacturing all-solid-state battery, and method for partially manufacturing electrolyte sheet

Abstract

This method for producing an electrolyte sheet comprises: a step for providing a porous support having a dense region and a non-dense region; an electrolyte filling step for filling the non-dense region with a solid electrolyte to form an electrolyte region and obtain an electrolyte filler; and a cutting step for cutting the electrolyte filler in the dense region to obtain a plurality of electrolyte sheets.

Description

Method for manufacturing an electrolyte sheet, method for manufacturing an all-solid-state battery, and method for partially manufacturing an electrolyte sheet

[0001] The present invention relates to a method for manufacturing an electrolyte sheet, a method for manufacturing an all-solid-state battery, and a method for partially manufacturing an electrolyte sheet.

[0002] All-solid-state batteries using solid electrolytes are known. Known examples of such all-solid-state batteries include an electrolyte sheet in which the solid electrolyte is supported on a porous support. Supporting the solid electrolyte on a porous support allows the electrolyte layer to have self-supporting properties, making it possible to handle the electrolyte sheet independently.

[0003] In the all-solid-state battery described above, the electrolyte sheet can be obtained by filling a porous support with a solid electrolyte. In this regard, for example, Patent Document 1 (JP-A 2021-533542) describes a method of preparing a laminated structure including a porous substrate and a film-like solid electrolyte material, and then pressurizing the laminated structure to force the solid electrolyte material into the porous substrate.

[0004] In order to mass-produce all-solid-state batteries, it is necessary to improve productivity. One of the challenges in all-solid-state batteries having an electrolyte sheet in which a solid electrolyte is supported on a porous support is to improve the productivity of the electrolyte sheet.

[0005] Therefore, an object of the present invention is to provide a technique capable of increasing the productivity of electrolyte sheets in all-solid-state batteries that use electrolyte sheets in which a solid electrolyte is supported on a porous support.

[0006] In one aspect, a method for manufacturing an electrolyte sheet according to the present invention includes: a porous support providing step of providing a porous support having a dense region and a non-dense region that is less dense than the dense region; an electrolyte filling step of filling a solid electrolyte into the non-dense region to form an electrolyte region, thereby obtaining an electrolyte filled body having an electrolyte region and a dense region; and a cutting step of cutting the electrolyte filled body at the dense region after the electrolyte filling step to obtain a plurality of electrolyte sheets.

[0007] In one aspect, a method for manufacturing an all-solid-state battery according to the present invention includes the steps of manufacturing an electrolyte sheet according to the above-described method for manufacturing an electrolyte sheet, and laminating an electrode layer on the electrolyte region.

[0008] FIG. 1 is a schematic plan view showing a method for manufacturing an electrolyte sheet according to a first embodiment. FIG. 2 is a schematic cross-sectional view showing a method for manufacturing an electrolyte sheet according to the first embodiment. FIG. 3 is a schematic view showing an example of a method for manufacturing an all-solid-state battery. FIG. 4 is a schematic view showing a modified example of the first embodiment. FIG. 5 is a schematic cross-sectional view showing an electrolyte filled body according to a second embodiment. FIG. 6 is a schematic cross-sectional view showing an electrolyte filled body according to a modified example of the second embodiment. FIG. 7 is a schematic cross-sectional view showing an electrolyte filled body according to a third embodiment. FIG. 8 is a schematic cross-sectional view showing an electrolyte filled body according to a modified example of the third embodiment.

[0009] Hereinafter, an embodiment of the present invention will be described.

[0010] In this specification, the term "all-solid-state battery" refers to a secondary battery in which the electrolyte layer, the positive electrode layer, and the negative electrode layer are all substantially solid. Each layer may be "substantially" solid, and a small amount of liquid material may be used.

[0011] (1) First Embodiment First, a first embodiment will be described. The electrolyte sheet manufactured by this embodiment is an electrolyte sheet for an all-solid-state battery. This electrolyte sheet has a porous support and a solid electrolyte filled in the pores of the porous support. The electrolyte sheet is self-supporting. Therefore, the electrolyte sheet obtained by this embodiment can be handled independently.

[0012] Fig. 1 is a schematic plan view showing a method for manufacturing an electrolyte sheet according to the present embodiment, and Fig. 2 is a schematic cross-sectional view showing a method for manufacturing an electrolyte sheet according to the present embodiment.

[0013] The method for manufacturing an electrolyte sheet according to this embodiment generally includes a porous support providing step (step S1), an electrolyte filling step (step S2), and a cutting step (step S3). Each step will be described in detail below.

[0014] (Step S1) Porous Support Providing Step First, as shown in Figure 1(a) and Figure 2(a), a pre-densification porous body 1 is prepared. In this embodiment, the pre-densification porous body 1 has a rectangular shape.

[0015] For example, a material containing fiber can be used as the pre-densification porous body 1. For example, a resin nonwoven fabric can be used as the pre-densification porous body 1. Examples of nonwoven fabrics include polyester nonwoven fabric, polyethylene nonwoven fabric, and cellulose fiber nonwoven fabric. The thickness of the porous body is, for example, 5 to 100 μm, preferably 7 to 20 μm.

[0016] Next, as shown in Figures 1(b) and 2(b), a partial region of the pre-densification porous body 1 is densified to form a dense region 3. This results in a porous support 2 having a dense region 3 and a non-dense region 4. The non-dense region 4 is an undensified region and is less dense than the dense region 3. In other words, the dense region 3 is a region with a high density, and the non-dense region 4 is a region with a low density.

[0017] In this embodiment, the dense region 3 is provided so as to surround the non-dense region 4. In this embodiment, the dense region 3 has a lattice pattern.

[0018] The densification method is not particularly limited. For example, the dense region 3 can be formed by heat fusion using a hot press or the like, or by resin filling. If heat fusion is used, the dense region 3 can be formed without using any other material. On the other hand, if resin filling is used, the dense region 3 can be formed without applying heat.

[0019] The configuration of the dense region 3 is not particularly limited. For example, when the pre-densification porous body 1 has a nonwoven fabric, the dense region 3 can be formed by reducing the opening ratio. That is, in one embodiment, the opening ratio of the dense region 3 is smaller than the opening ratio of the non-dense region 4. The opening ratio can be reduced, for example, by the above-mentioned heat fusion or resin filling.

[0020] Alternatively, when the pre-densified porous body 1 is made of a material containing fibers (e.g., a nonwoven fabric), the dense region 3 can be formed by changing the cross-sectional shape of the fibers from a circular state to a flat state. That is, in one embodiment, the cross-sectional shape of the fibers contained in the dense region 3 is flatter than the cross-sectional shape of the fibers contained in the non-dense region 4. For example, the cross-sectional shape of the fibers can be changed to a flat state by performing a heat press.

[0021] The above is a description of the porous support providing step. Note that the above description has been given of the case where a pre-densification porous body 1 is prepared and then a portion of the pre-densification porous body 1 is densified. However, if a porous support 2 having a dense region 3 and a non-dense region 4 is commercially available, a commercially available product may be used as the porous support 2. In other words, in this step (porous support providing step), it is not necessary to prepare a pre-densification porous body 1, and it is sufficient to simply prepare a commercially available porous support 2.

[0022] (Step S2) Electrolyte Filling Step Next, as shown in FIGS. 1( c) and 2(c), the non-dense region 4 is filled with a solid electrolyte. This forms an electrolyte region 6. That is, the porous support 2 provided with the electrolyte region 6 and the dense region 3 is obtained as an electrolyte-filled body 5.

[0023] The method for filling the solid electrolyte is not particularly limited. For example, a slurry containing a solid electrolyte, a binder, and a solvent is prepared. The slurry is then supplied to the non-dense region 4. This allows the solid electrolyte to be filled into the non-dense region 4. Alternatively, the solid electrolyte may be filled into the non-dense region 4 by immersing the porous support 2 in the slurry.

[0024] (Step S3) Cutting Step Subsequently, as shown in Figures 1(c) and 1(d), the electrolyte filling body 5 is cut in the dense region 3. As a result, a plurality of electrolyte sheets 7 are obtained.

[0025] According to this embodiment, the dense region 3 is provided, thereby improving productivity. If the dense region 3 were not provided, i.e., if the entire region of the electrolyte filler 5 were filled with solid electrolyte, it would be difficult to properly cut the electrolyte filler 5. Solid electrolytes are generally powders that are hard and brittle. Therefore, it is difficult to cut the electrolyte filler 5 as intended in the region filled with solid electrolyte. In contrast, the dense region 3 is easy to cut as intended. That is, according to this embodiment, the dense region 3 is provided, so it is possible to cut the electrolyte filler 5 along the dense region 3. As a result, it is possible to produce multiple electrolyte sheets 7 from a single pre-densification porous body 1, improving productivity.

[0026] (Manufacturing of All-Solid-State Battery) As described above, the obtained electrolyte sheet 7 is used to manufacture an all-solid-state battery. FIG. 3 is a schematic diagram showing an example of a method for manufacturing an all-solid-state battery. As shown in FIG. 3, an electrode layer is laminated on the electrolyte region 6 of the electrolyte sheet 7. Specifically, a positive electrode layer 9 and a negative electrode layer 10 are laminated as electrode layers so as to sandwich the electrolyte region 6. The laminate is then pressed to compress the electrode layer. This reduces the interfacial resistance between the electrode layers (positive electrode layer 9 and negative electrode layer 10) and the electrolyte sheet 7. Note that the pressing can also adhere the filled solid electrolyte to the porous support in the electrolyte region 6. Thereafter, other necessary components are attached to obtain an all-solid-state battery.

[0027] The method for manufacturing the electrolyte sheet and the all-solid-state battery according to this embodiment has been described above.

[0028] Note that the electrolyte sheet 7 may be pressed after the electrolyte filling step (step S2) and before the electrolyte sheet 7 and the electrode layers are laminated together. If the electrolyte region 6 is pressed after being filled with the solid electrolyte, the filled solid electrolyte can be attached to the porous support 2 at that point.

[0029] In addition, in this embodiment, the dense region 3 is provided so as to surround the electrolyte region 6. Here, it is preferable that the dense region 3 has electronic insulation and lower ionic conductivity than the electrolyte region 6. By adopting such a configuration, the dense region 3 functions as an insulating layer in the all-solid-state battery. This prevents short circuits at the ends of the electrolyte layer, improving safety. Note that the electronic insulation properties of the dense region 3 can be adjusted by using an insulating material as the pre-densification porous body 1.

[0030] In addition, in this embodiment, the case where the pre-densified porous body 1 is rectangular and the dense regions 3 are lattice-shaped has been described. By adopting such a layout, a large number of electrolyte sheets 7 can be efficiently obtained from a single pre-densified porous body 1. Furthermore, in the obtained electrolyte sheet 7, as described above, the dense regions 3 are provided so as to surround the electrolyte regions 6. Therefore, as described above, the dense regions 3 can function as insulating layers in the all-solid-state battery.

[0031] On the other hand, the shape of the pre-densified porous body 1 does not need to be limited to a rectangular shape. Also, the dense region 3 does not need to be provided so as to surround the non-dense region 4.

[0032] For example, Fig. 4 is a schematic diagram showing a modified example of this embodiment, illustrating the layout of the dense region 3. In this modified example, the dense region 3 is not lattice-shaped, but extends so as to divide the electrolyte filling body 5 into four parts. Even when such a layout is adopted, multiple electrolyte sheets 7 can be obtained from a single pre-densification porous body 1 (electrolyte filling body 5), thereby improving productivity.

[0033] (2) Second Embodiment Next, a second embodiment will be described. In this embodiment, step S2 (electrolyte filling step) is further specified. Note that detailed description of the same configuration as in the first embodiment will be omitted.

[0034] 5 is a schematic cross-sectional view showing an electrolyte filler 5 in this embodiment. In this embodiment, in the electrolyte filling step, a slurry containing a solid electrolyte is applied to both the dense region 3 and the non-dense region 4. As a result, the solid electrolyte is filled into the non-dense region 4, forming an electrolyte region 6. In addition, an electrolyte coating layer 8 is formed on both the electrolyte region 6 and the dense region 3.

[0035] Thereafter, as in the first embodiment, the electrolyte filling body 5 is cut at the dense region 3. At this time, although the electrolyte coating layer 8 is present on the dense region 3, the thickness of the electrolyte coating layer 8 can be made thin, so that no significant obstacles arise during cutting. Furthermore, even if a crack or the like occurs in the electrolyte coating layer 8 on the dense region 3, the characteristics will not be significantly affected as long as it is on the dense region 3.

[0036] The electrolyte coating layer 8 may be formed on both sides. Fig. 6 is a schematic cross-sectional view showing an electrolyte filled body 5 in a modified example of this embodiment. In the example shown in Fig. 6, the electrolyte coating layer 8 is formed on both sides of the electrolyte filled body 5. Such an electrolyte filled body 5 can be formed, for example, by applying a slurry containing a solid electrolyte to both sides of the porous support 2. Alternatively, it can also be obtained by immersing the porous support 2 in a slurry containing a solid electrolyte.

[0037] (3) Third Embodiment Next, a third embodiment will be described. This embodiment can be considered a modification of the second embodiment. Detailed description of the features that can employ the same configuration as the second embodiment will be omitted.

[0038] FIG. 7 is a schematic cross-sectional view showing an electrolyte filler 5 according to this embodiment. In this embodiment, a slurry containing a solid electrolyte is applied to the porous support 2, and then the solid electrolyte is removed from above the dense region 3. The solid electrolyte can be partially removed, for example, with a scraper or the like. Thereafter, as in the previously described embodiment, the electrolyte filler 5 is cut at the dense region 3. This method allows for accurate cutting because the electrolyte coating layer 8 is not present on the dense region 3 during cutting. Furthermore, unnecessary use of solid electrolyte can be suppressed, thereby reducing the cost required for the solid electrolyte.

[0039] 8 is a schematic cross-sectional view showing an electrolyte filler 5 in a modified example of this embodiment. In this embodiment, as in the second embodiment, the electrolyte coating layer 8 may be formed on both sides of the electrolyte filler 5.

[0040] Furthermore, in this embodiment, the solid electrolyte may be removed not only from the dense region 3 but also from the electrolyte region 6. That is, the solid electrolyte only needs to fill the pores in the non-dense region 4, and may not be present on the surface of the porous support 2. That is, the electrolyte coating layer 8 may not be present. By employing such a method, the thickness of the electrolyte sheet 7 becomes uniform, and the variation in ionic conductivity in the all-solid-state battery can be reduced. This can improve the rate and cycle characteristics.

[0041] The present invention has been described above with reference to the first to third embodiments. Note that these embodiments and modifications are not independent of each other and can be implemented in combination as long as there is no contradiction.

[0042] The following will summarize, as an appendix, representative relationships between the configuration and the effects of this embodiment.

[0043] (Supplementary Note 1) A method for manufacturing an electrolyte sheet includes: a porous support providing step (step S1) of providing a porous support 2, the porous support 2 having a dense region 3 and a non-dense region 4 that is a region less dense than the dense region 3; an electrolyte filling step (step S2) of filling the non-dense region 4 with a solid electrolyte to form an electrolyte region 6, thereby obtaining an electrolyte filled body 5 having the electrolyte region 6 and a dense region 3; and a cutting step (step S3) of cutting the electrolyte filled body 5 at the dense region 3 after the electrolyte filling step (step S2) to obtain a plurality of electrolyte sheets 7.

[0044] According to this method, the electrolyte filler 5 can be cut in the dense region 3, so that a plurality of electrolyte sheets 7 can be obtained from one raw material, thereby improving productivity.

[0045] (Supplementary Note 2) A method for manufacturing an electrolyte sheet according to Supplementary Note 1, wherein the porous support providing step (step S1) includes a step of preparing a pre-densification porous body 1 of the porous support, and a step of densifying a partial region of the pre-densification porous body 1 to form a dense region 3, thereby obtaining a porous support 2.

[0046] According to this method, a porous support 2 having non-dense regions 4 in addition to dense regions 3 can be obtained.

[0047] (Supplementary Note 3) The method for manufacturing an electrolyte sheet according to Supplementary Note 1 or 2, wherein the dense region 3 is provided so as to surround the non-dense region 4.

[0048] According to this method, an electrolyte sheet can be obtained in which the dense region 3 is provided so as to surround the electrolyte region 6. Therefore, when used in a battery, the dense region 3 can be used as an insulator to prevent short circuits.

[0049] (Supplementary Note 4) The method for manufacturing an electrolyte sheet according to Supplementary Note 3, wherein the dense region 3 has a lattice pattern.

[0050] According to this method, for example, when the raw material is rectangular, a plurality of electrolyte sheets can be efficiently cut out.

[0051] (Supplementary Note 5) A method for manufacturing an electrolyte sheet according to any one of Supplementary Notes 1 to 4, wherein the opening rate in the dense region 3 is smaller than the opening rate in the non-dense region 4, and / or the cross-sectional shape of the fibers contained in the dense region 3 is flatter than the cross-sectional shape of the fibers contained in the non-dense region 4.

[0052] By this method, the dense region 3 can be formed.

[0053] (Supplementary Note 6) The method for manufacturing an electrolyte sheet according to any one of Supplementary Notes 1 to 5, wherein the dense region 3 is a heat-sealed region or a region filled with a resin.

[0054] By this method, the dense region 3 can be formed.

[0055] (Supplementary Note 7) A method for manufacturing an electrolyte sheet according to any one of Supplementary Notes 1 to 6, wherein the dense region 3 has electronic insulation and lower ionic conductivity than the electrolyte region 6.

[0056] According to this method, when used in a battery, the dense region 3 can be used as an insulator to prevent short circuits.

[0057] (Appendix 8) The method for manufacturing an electrolyte sheet according to any one of Appendices 1 to 7, wherein the electrolyte filling step (step S2) includes applying a slurry containing a solid electrolyte onto both the dense region 3 and the non-dense region 4.

[0058] According to this method, the non-dense region 4 can be filled with the solid electrolyte.

[0059] (Supplementary Note 9) The method for manufacturing an electrolyte sheet according to Supplementary Note 8, further comprising the step of removing the solid electrolyte from above the dense region 3 after the step of applying the slurry.

[0060] This method allows for more accurate cutting because the solid electrolyte does not interfere with the cutting process, and also reduces the cost of the solid electrolyte.

[0061] (Supplementary Note 10) A method for manufacturing an all-solid-state battery, comprising: a step of manufacturing an electrolyte sheet according to the manufacturing method described in any one of Supplementary Notes 1 to 9; and a step of stacking an electrode layer on the electrolyte region 6.

[0062] According to this method, an all-solid-state battery can be obtained using an electrolyte sheet.

[0063] (Supplementary Note 11) The method for manufacturing an all-solid-state battery according to Supplementary Note 10, further comprising a step of pressing the electrolyte filler 5 after the electrolyte filling step (step S2).

[0064] According to this method, the solid electrolyte can be deposited on the porous support 2 in the electrolyte region 6 .

[0065] (Appendix 12) A partial manufacturing method of an electrolyte sheet, which constitutes a part of the manufacturing method of an electrolyte sheet described in any one of Appendices 1 to 9, comprising at least one of a porous support providing step (step S1), an electrolyte filling step (step S2), and a cutting step (step S3).

[0066] The partial manufacturing method according to Supplementary Note 12 is intended to be included in the present invention as long as at least one of steps S1 to S3 is performed. For example, if any of steps S1 to S3 is performed domestically by a single business operator, even if the remaining steps are performed overseas by another business operator, the performance of the steps domestically by that single business operator can be considered to be an implementation of the present invention.

Claims

1. A method for manufacturing an electrolyte sheet, comprising: a porous support providing step, the porous support having a dense region and a non-dense region which is less dense than the dense region; an electrolyte filling step, a solid electrolyte is filled into the non-dense region to form an electrolyte region, thereby obtaining an electrolyte filled body having the electrolyte region and the dense region; and a cutting step, after the electrolyte filling step, cutting the electrolyte filled body at the dense region to obtain a plurality of electrolyte sheets.

2. A method for manufacturing an electrolyte sheet as described in claim 1, wherein the porous support providing step comprises the steps of: preparing a pre-densified porous body; and forming the dense region by densifying a partial region of the pre-densified porous body, thereby obtaining the porous support.

3. A method for manufacturing an electrolyte sheet according to claim 1 or 2, wherein the dense region is provided so as to surround the non-dense region.

4. A method for manufacturing an electrolyte sheet according to claim 3, wherein the dense region is in a lattice pattern.

5. A method for manufacturing an electrolyte sheet as described in claim 1 or 2, wherein the opening rate in the dense region is smaller than the opening rate in the non-dense region, and / or the cross-sectional shape of the fibers contained in the dense region is flatter than the cross-sectional shape of the fibers contained in the non-dense region.

6. A method for manufacturing an electrolyte sheet according to claim 1 or 2, wherein the dense region is a heat-sealed region or a region filled with a resin.

7. A method for producing an electrolyte sheet according to claim 1 or 2, wherein the dense region has electronic insulation and lower ionic conductivity than the electrolyte region.

8. A method for manufacturing an electrolyte sheet according to claim 1 or 2, wherein the electrolyte filling step includes a step of applying a slurry containing a solid electrolyte onto both the dense region and the non-dense region.

9. The method for producing an electrolyte sheet according to claim 8, further comprising the step of removing the solid electrolyte from above the dense region after the step of applying the slurry.

10. A method for producing an all-solid-state battery, comprising: producing an electrolyte sheet according to the method of claim 1 or 2; and laminating an electrode layer on the electrolyte region.

11. A method for producing an all-solid-state battery according to claim 10, further comprising a step of pressing the electrolyte filling body after the electrolyte filling step.

12. A method for partially manufacturing an electrolyte sheet, constituting a part of the method for manufacturing an electrolyte sheet according to claim 1 or 2, comprising at least one of the steps of providing a porous support, filling the electrolyte, and cutting.

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