Method for manufacturing electrode composite sheets for secondary batteries and jig for forming inclined surfaces

Abstract

To provide a technology that allows for easy roll pressing and enables roll pressing to be performed in a way that ensures uniform density of the material sheet. [Solution] The method for manufacturing an electrode composite sheet for secondary batteries comprises the steps of: compressing the front end of a material sheet, which is the material for the electrode composite sheet for secondary batteries, so that an inclined surface is formed where the thickness decreases towards the front; and, after the compression step, rolling-pressing the material sheet with the front end as the pressing start position.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an electrode composite sheet for a secondary battery and an inclined surface forming jig.

Background Art

[0002] When manufacturing a secondary battery such as an all-solid-state battery, an electrode composite sheet may be used. The electrode composite sheet is a member in which materials (such as electrode active materials) used as electrode layers are pre-sheeted using a binder or the like. A secondary battery is manufactured by combining the electrode composite sheet and a member for forming an electrolyte layer or the like.

[0003] When manufacturing the electrode composite sheet itself, roll pressing may be performed. By performing roll pressing, the thickness of the electrode composite sheet can be made the desired thickness (see, for example, paragraph 0025 of Patent Document 1, etc.).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Roll pressing is usually performed using a pair of rolls. Specifically, a pair of rolls arranged in parallel and having a predetermined gap is provided, and a sheet (hereinafter referred to as a material sheet) that becomes the material of the electrode composite sheet is passed between the pair of rolls. The material sheet is bitten by the pair of rolls and rolled. Thereby, the thickness of the material sheet is adjusted.

[0006] However, if the thickness of the material sheet is too large with respect to the roll gap, it may be difficult for the material sheet to be bitten. Therefore, it becomes difficult to perform roll pressing.

[0007] Furthermore, from the viewpoint of obtaining the desired energy density and discharge capacity, it is preferable that the electrode composite sheet has a uniform density. Therefore, when performing roll pressing, it is necessary to perform the roll pressing in such a way that the density of the material sheet becomes uniform.

[0008] Therefore, the object of the present invention is to provide a technology that allows for easy roll pressing and enables roll pressing to be performed in a way that ensures uniform density of the material sheet. [Means for solving the problem]

[0009] In one aspect, the present invention relates to a method for manufacturing an electrode composite sheet for secondary batteries. This manufacturing method comprises the steps of: compressing the front end of a material sheet, which is the material for the electrode composite sheet for secondary batteries, so as to form an inclined surface in which the thickness decreases towards the front; and, after the compression step, rolling-pressing the material sheet with the front end as the pressing start position. [Effects of the Invention]

[0010] The present invention provides a technology that allows for easy roll pressing and enables roll pressing to be performed in a way that ensures uniform density of the material sheet. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a flowchart showing an example of a manufacturing method for electrode composite sheets for secondary batteries. [Figure 2A] Figure 2A is a schematic cross-sectional view showing the material sheet in step S10. [Figure 2B] Figure 2B is a schematic perspective view showing the situation in step S10. [Figure 3] Figure 3 is a schematic cross-sectional view showing a reference example. [Figure 4] Figure 4 is a schematic cross-sectional view showing step S4 (roll press) in the first embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view showing another example. [Figure 6] Figure 6 is a schematic cross-sectional view showing the configuration of the material sheet in step S10. [Figure 7] Figure 7 is a schematic cross-sectional view showing a preferred modification of the second embodiment. [Figure 8] Figure 8 is a schematic cross-sectional view showing step S3 (step S10) in the third embodiment. [Figure 9A] Figure 9A is a schematic cross-sectional view showing a preferred modification in the third embodiment. [Figure 9B] Figure 9B is a schematic cross-sectional view showing a preferred modification in the third embodiment. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the drawings.

[0013] (1) First Embodiment This embodiment relates to a method for manufacturing an electrode composite sheet for secondary batteries. The electrode composite sheet for secondary batteries manufactured by this embodiment is used as an electrode layer in a secondary battery, as described above.

[0014] FIG. 1 is a flowchart showing an example of a method for manufacturing an electrode composite sheet for a secondary battery. Generally, first, powder treatment is carried out (step S1). For example, powder materials (electrode active material, electrolyte, conductive assistant, etc.) constituting the electrode layer and a binder (binder... PTFE, etc.) are dispersed and kneaded. After the powder treatment, the mixture is formed into a sheet shape (step S2). That is, the mixture is sheeted. Thereby, a material sheet is obtained. Subsequently, the material sheet is roughly cut (step S3). Subsequently, the material sheet is roll-pressed (step S4). Subsequently, the material sheet is finally cut (step S5). Thereby, an electrode composite sheet for a secondary battery is obtained. With respect to the obtained electrode composite sheet for a secondary battery, other members (solid electrolyte layer, current collector foil, etc.) are laminated, and a secondary battery is obtained (step S6).

[0015] Here, in the present embodiment, before roll pressing (step S4), the front end portion of the material sheet is compressed to form an inclined surface (step S10). By forming the inclined surface, when roll pressing (step S4) is performed, the material sheet is more likely to be bitten in. Also, roll pressing can be performed so that the density becomes uniform. This point will be described in detail below.

[0016] FIG. 2A is a schematic cross-sectional view showing the material sheet 1 in step S10. FIG. 2B is a perspective view schematically showing step S10. In FIG. 2A, the front and the rear are shown. The "front" and "rear" mentioned here respectively mean the "front" and "rear" directions with respect to the direction in which the material sheet 1 is sent during roll pressing. That is, during roll pressing (step S4), with the front end portion (front end) on the front side of the material sheet 1 as the press start position, the material sheet 1 is roll-pressed.

[0017] As shown in FIG. 2A, in step S10, an inclined surface 5 is formed at the front end portion of the material sheet 1. The inclined surface 5 is formed such that the thickness of the material sheet 1 becomes smaller toward the front.

[0018] Specifically, the inclined surface forming jig 2 is pressed against the front end of the material sheet 1. The inclined surface forming jig 2 is provided with an inclined surface 3 for forming an inclined surface 5. By pressing the inclined surface forming jig 2 against the front end of the material sheet 1, an inclined surface 5 is formed according to the inclined surface 3.

[0019] Because an inclined surface 5 is formed, the material sheet 1 becomes easier to grip in the subsequent step S4 (roll press). This point will be explained with reference to Figures 3 and 4.

[0020] Figure 3 is a schematic cross-sectional view showing a reference example, illustrating the material sheet 1 during roll pressing. In this reference example, the material sheet 1 does not have an inclined surface 5. During roll pressing, as described above, the material sheet 1 is passed between a pair of rolls (6-1 to 6-2) having a predetermined roll gap. Because there is no inclined surface 5, the contact area between the material sheet 1 and the pair of rolls (6-1 to 6-2) is reduced. As a result, the material sheet 1 is less likely to get caught in the pair of rolls (6-1 to 6-2).

[0021] In contrast, Figure 4 is a schematic cross-sectional view showing step S4 (roll press) in this embodiment. In this embodiment, an inclined surface 5 is formed. Therefore, when the material sheet 1 comes into contact with the pair of rolls (6-1 to 6-2), the contact area between the material sheet 1 and each roll 6 (6-1 to 6-2) tends to be larger. As a result, the material sheet 1 is more easily gripped by the pair of rolls (6-1 to 6-2). Thus, roll pressing can be easily performed.

[0022] In addition, according to this embodiment, the inclined surface 5 is formed by "compression" in step S10. Therefore, it is possible to roll press the material sheet 1 to achieve a uniform density. This point will be explained with reference to Figure 5. Figure 5 is a schematic cross-sectional view showing another reference example. In this reference example, as shown in Figure 5(a), the inclined surface 5 is formed by cutting a part of the front end of the material sheet 1. Then, as shown in Figures 5(b) and (c), the roll press is performed with the front end of the material sheet 1 as the pressing start position.

[0023] In the reference example shown in Figure 5, as in this embodiment, an inclined surface 5 is provided, making it easier for the material sheet 1 to be caught in the pair of rolls (6-1 to 6-2). However, because the inclined surface 5 is formed by "cutting," the density of the front end of the material sheet 1 after roll pressing is lower than that of other parts (see low-density portion 7 in Figure 5(c)). As a result, it becomes difficult to obtain an electrode composite sheet with uniform density.

[0024] In contrast, according to this embodiment, since the inclined surface 5 is formed by "compression," the density of the material sheet 1 after roll pressing remains the same between the front end and the other parts. That is, the material sheet 1 can be roll-pressed to have a uniform density.

[0025] The above is an outline of this embodiment. As described above, according to this embodiment, an inclined surface 5 is formed on the front end of the material sheet 1 before roll pressing. Therefore, it is possible to make it easier to grip the material sheet 1 between the pair of rolls during roll pressing. In addition, the inclined surface 5 is formed by "compressing" the front end of the material sheet 1. Therefore, the density of the material sheet 1 after roll pressing can be made uniform.

[0026] In a preferred embodiment, during the formation of the inclined surface 5 (step S4), the front end of the material sheet 1 is compressed while the front end surface of the material sheet 1 is held down to prevent it from spreading in the planar direction. For details, please refer again to Figure 2A. In the example shown in Figure 2A, the inclined surface forming jig 2 has a front end pressing surface 4 in addition to the inclined surface forming surface 3. The front end pressing surface 4 is provided to hold down the front end surface of the material sheet 1. By using such an inclined surface forming jig 2, the material sheet 1 does not spread in the planar direction (forward) during compression (when the inclined surface 5 is formed). Therefore, the density of the material sheet 1 after roll pressing can be made more uniform.

[0027] In this embodiment, the inclination angle α of the inclined surface 5 (see Figure 2) is not particularly limited, as long as it is large enough to make it easier for the material sheet 1 to be gripped by the pair of rolls. However, preferably, the inclination angle α is set within the range expressed by the following formula 1, using the thickness t of the material sheet 1 before roll pressing (see Figure 4(a)), the roll gap G (see Figure 4(a)), and the roll radius R (not shown). Within the range of values ​​shown in the following formula 1, the material sheet 1 will be easier to grip between the pair of rolls.

[0028] (Formula 1)0<α <arccos(1-(t-G) / R)

[0029] The thickness t of the material sheet 1 before roll pressing is, for example, 50 to 200 μm. The roll gap G is, for example, 50 to 200 μm. The roll radius R is, for example, 150 to 300 mm.

[0030] Preferably, when forming the inclined surface 5 (see Figure 2A), the front end of the material sheet 1 is compressed so that the thickness of the front end surface of the material sheet 1 becomes equal to the thickness of the material sheet 1 after roll pressing. This method makes the density distribution of the material sheet 1 after roll pressing more uniform.

[0031] The electrode composite sheet for secondary batteries obtained by the method according to this embodiment can be any electrode composite sheet used for secondary batteries. However, it is preferably an electrode composite sheet used as the positive electrode layer of an all-solid-state battery. In all-solid-state batteries, the material density of the electrode composite sheet, in particular the material density of the electrode composite sheet for the positive electrode layer, greatly affects the energy density and discharge capacity. According to this embodiment, the material density of the electrode composite sheet can be made uniform. Therefore, this embodiment has particular value when applied to an electrode composite sheet for the positive electrode layer of an all-solid-state battery.

[0032] (2) Second embodiment Next, a second embodiment will be described. In this embodiment, step S10 (formation of an inclined surface by compression) has been improved. Details regarding the fact that the same configuration as in the first embodiment can be adopted will be omitted.

[0033] Figure 6 is a schematic cross-sectional view showing step S10 (formation of an inclined surface by compression) in the method according to this embodiment.

[0034] In this embodiment, in step S10, the front end of the material sheet 1 is compressed while both the front and rear end surfaces of the material sheet 1 are held down. That is, the inclined surface forming jig 2 has a rear end pressing surface 9 in addition to the inclined surface 3 and the front end pressing surface 4. In step S10 (formation of an inclined surface by compression), the rear end surface of the material sheet 1 is held down by the rear end pressing surface 9. This prevents the material sheet 1 from spreading backward.

[0035] According to this embodiment, the material sheet 1 is prevented from spreading not only forward but also backward. Therefore, dimensional changes in the material sheet 1 are more reliably suppressed. The material sheet 1 tends to spread in the front-rear direction during roll pressing (step S4). In order to obtain a uniform density, it is preferable to suppress the spreading of the material sheet 1 in the front-rear direction as much as possible. According to this embodiment, in step S10 (formation of an inclined surface by compression), the spreading of the material sheet 1 not only forward but also backward is suppressed, so an electrode composite sheet with a more uniform density can be obtained.

[0036] Figure 7 is a schematic cross-sectional view showing a preferred modification of this embodiment. Figure 7 shows a cross-sectional configuration perpendicular to the front-rear direction. In this modification, the inclined surface forming jig 2 further has a pair of left and right pressing surfaces 10. The pair of left and right pressing surfaces 10 are configured to press the end faces of the material sheet 1 in the left-right direction. That is, in this modification, when the inclined surface 5 is formed by compression, the front end of the material sheet 1 is compressed while the entire circumference of the end faces of the material sheet 1 (the end faces in the front-rear direction and the end faces in the left-right direction) is pressed.

[0037] According to the modified example shown in Figure 7, the spreading of the material sheet 1 is suppressed in all directions in the planar direction. This makes it possible to obtain an electrode composite sheet with a more uniform density.

[0038] (3) Third Embodiment Next, a third embodiment will be described. Detailed explanations will be omitted regarding aspects where the same configuration as the previously described embodiments can be adopted.

[0039] Please refer to Figure 1. In the previously described embodiment, as shown in Figure 1, the case in which step S10 (formation of an inclined surface by compression) is performed between step S3 (rough cutting) and step S4 (roll press) was explained. In contrast, in this embodiment, step S10 (formation of an inclined surface by compression) is performed simultaneously with step S3 (rough cutting).

[0040] Please refer to Figure 8. Figure 8 is a schematic cross-sectional view showing step S3 (step S10) in this embodiment. In this embodiment, the material sheet 1 is cut by the inclined surface forming jig 2.

[0041] Specifically, the inclined surface forming jig 2 has an inclined surface 3 as well as a single-edged structure 8-1 for the front end.

[0042] The front-end single-edged structure 8-1 has a cutting edge 11, a front-end pressing surface 4, and a back surface 12. The front-end pressing surface 4 and the back surface 12 intersect at the lower end so that the cutting edge 11 is formed therein. In this front-end single-edged structure 8-1, the material sheet 1 is cut by the cutting edge 11. The front-end pressing surface 4 contacts the front end surface of the material sheet 1 after it has been cut. This prevents the material sheet 1 from spreading forward.

[0043] The inclined forming surface 3 is located inside the front end single-edged structure 8-1. As a result, similar to the embodiment described above, the inclined forming surface 3 is pressed against the front end of the material sheet 1, forming the inclined surface 5.

[0044] According to this embodiment, step S3 (rough cutting) and step S10 (formation of an inclined surface by compression) are performed simultaneously. Therefore, the manufacturing process can be reduced.

[0045] Figures 9A and 9B are schematic cross-sectional views showing preferred modifications in this embodiment, respectively.

[0046] In the modified example shown in Figure 9A, the inclined surface forming jig 2 has a rear end single-blade structure 8-2 in addition to the front end single-blade structure 8-1. The rear end single-blade structure 8-2 is configured to cut the rear end of the material sheet 1. The rear end single-blade structure 8-2 is provided with a rear end pressing surface 9 that contacts the rear end surface of the material sheet 1 after cutting. With this configuration, not only the front end but also the rear end of the material sheet 1 can be cut. In addition, the material sheet 1 can be prevented from spreading backward during the cutting process.

[0047] In the modified example shown in Figure 9B, the inclined surface forming jig 2 is further configured to cut the edges in the left-right direction in addition to the front-back direction. Specifically, the inclined surface forming jig 2 has a single-edged structure 8-3 for the left and right edges, which is configured to cut the edges in the left-right direction. Inside each single-edged structure 8-3, left and right pressing surfaces 10 are provided. The left and right pressing surfaces 10 are configured to press the left and right edge surfaces of the material sheet 1 so that the material sheet 1 does not spread in the left-right direction. With this modified example, the spreading of the material sheet 1 is suppressed in all directions in the surface direction, so that an electrode composite sheet with a more uniform density can be obtained.

[0048] The present invention has been described above with reference to embodiments and modifications. These embodiments and modifications are not independent of each other and can be combined and used within a non-inconsistent scope.

[0049] (Note) The following is a summary of the configuration examples included in the present invention and their effects, as an appendix.

[0050] (Note 1) A method for manufacturing an electrode composite sheet for secondary batteries, comprising: a step (S10) of compressing the front end of a material sheet 1, which is the material for the electrode composite sheet for secondary batteries, so as to form an inclined surface 5 such that the thickness decreases towards the front; and a step (S4) of roll pressing the material sheet 1 after the compression step (S10), with the front end as the pressing start position.

[0051] According to the method described above, an inclined surface is formed, making it easier for the material sheet to be caught in the roll during roll pressing. Furthermore, because the inclined surface is formed by "compression," a material sheet 1 with a uniform density can be obtained after roll pressing.

[0052] (Note 2) A manufacturing method as described in Appendix 1, wherein the compression step (S10) includes compressing the front end of the material sheet 1 while holding down the front end surface of the material sheet 1 so that the material sheet 1 does not spread in the planar direction.

[0053] According to the method described above, it is possible to prevent the material sheet from spreading out when forming the inclined surface.

[0054] (Note 3) A manufacturing method as described in Appendix 2, wherein the compression step (S10) further includes compressing the front end while holding down the rear end surface of the material sheet 1.

[0055] According to the method described above, it is also possible to prevent the material sheet from spreading out backward when forming the inclined surface.

[0056] (Note 4) A manufacturing method as described in Appendix 3, wherein the compression step (S10) further includes compressing the front end while holding down the entire circumference of the end face of the material sheet.

[0057] According to the method described above, it is possible to prevent the material sheet from spreading out in all directions when forming the inclined surface.

[0058] (Note 5) A manufacturing method as described in any of Appendix 1 to 4, wherein the compression step (S10) includes forming an inclined surface 5 by pressing an inclined surface forming jig 2 onto the material sheet 1.

[0059] According to the method described above, an inclined surface 5 can be formed by using the inclined surface forming jig 2.

[0060] (Note 6) A manufacturing method as described in Appendix 5, further comprising a cutting step of cutting a material sheet 1 using an inclined surface forming jig 2, wherein the compression step is performed in the cutting step, and the inclined surface forming jig 2 has a front end single-blade structure 8-1 configured to cut the front end of the material sheet, and an inclined surface 3 provided inside the front end single-blade structure 8-1 and pressed against the material sheet 1 so as to form an inclined surface 5, and the front end single-blade structure 8-1 has a front end pressing surface 4 that contacts the front end surface of the material sheet 1 after cutting.

[0061] According to the method described above, the cutting of the material sheet 1 and the formation of the inclined surface can be performed simultaneously. In addition, it is possible to prevent the material sheet 1 from spreading forward when the inclined surface is formed.

[0062] (Note 7) A manufacturing method as described in Appendix 6, further comprising a rear end single-blade structure 8-2 configured to cut the rear end of the material sheet 1, wherein the rear end single-blade structure 8-2 further has a rear end pressing surface 9 that contacts the rear end surface of the material sheet 1 after cutting.

[0063] According to the method described above, the rear end of the material sheet 1 and the inclined surface can be cut and formed simultaneously. Furthermore, it is possible to prevent the material sheet 1 from spreading out backward during the formation of the inclined surface.

[0064] (Note 8) A manufacturing method described in any of Appendix 1 to 7, wherein the compression step includes compressing the front end of the material sheet 1 such that the thickness of the front end surface of the material sheet 1 is equal to the thickness of the material sheet 1 after the roll pressing step.

[0065] According to the method described above, a material sheet with a more uniform density can be obtained.

[0066] (Note 9) A jig for forming an inclined surface, used in the manufacturing method described in any of Appendix 5 to 7. [Explanation of Symbols]

[0067] 1...Material sheet, 2...Jig for forming inclined surfaces, 3...Inclined forming surface, 4...Front end pressing surface, 5...Inclined surface, 6 (6-1~6-2)...Roll, 7...Low density section, 8 (8-1~8-3)...Single-edged structure, 9...Rear end pressing surface, 10...Left and right pressing surfaces, 11...Cutting edge, 12...Back

Claims

1. A process of compressing the front end of a material sheet, which is the material for the electrode composite sheet for secondary batteries, so that an inclined surface is formed where the thickness decreases towards the front, After the compression step, the material sheet is roll-pressed with the front end as the pressing start position, Equipped with, A method for manufacturing electrode composite sheets for secondary batteries.

2. A manufacturing method according to claim 1, The compression step includes compressing the front end of the material sheet while holding down the front end surface of the material sheet so that the material sheet does not spread in the planar direction. Manufacturing method.

3. A manufacturing method according to claim 2, The compression step further includes compressing the front end while holding down the rear end surface of the material sheet. Manufacturing method.

4. A manufacturing method according to claim 3, The compression step further includes compressing the front end while holding down the entire circumference of the end face of the material sheet. Manufacturing method.

5. A manufacturing method according to claim 1 or 2, The compression step includes forming the inclined surface by pressing the inclined surface forming jig against the material sheet. Manufacturing method.

6. A manufacturing method according to claim 5, Furthermore, A cutting step in which the material sheet is cut using the inclined surface forming jig, Equipped with, The compression step is performed in the cutting step, The aforementioned inclined surface forming jig is A single-edged cutting edge structure for the front end, configured to cut the front end of the material sheet, An inclined surface is provided inside the front end single-edged structure and is pressed against the material sheet so that the inclined surface is formed, It has, The aforementioned single-edged structure for the front end has a front end pressing surface that contacts the front end surface of the material sheet after cutting. Manufacturing method.

7. A manufacturing method according to claim 6, Furthermore, it is equipped with a single-edged structure for the rear end, configured to cut the rear end of the material sheet, The aforementioned single-edged structure for the rear end further has a rear end pressing surface that contacts the rear end surface of the material sheet after cutting. Manufacturing method.

8. A manufacturing method according to claim 1, The compression step includes compressing the front end of the material sheet such that the thickness of the front end surface of the material sheet is equal to the thickness of the material sheet after the roll pressing step. Manufacturing method.

9. An inclined surface forming jig used in the manufacturing method described in claim 5.

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