Electrode plate manufacturing method and electrode plate manufacturing device

Abstract

This method includes: a heating step for heating a part of a current collector sheet 12 having a coated region 13 coated with a mixture 11 containing an active material and an uncoated region 14 not coated with the mixture 11; and a compression step for compressing the current collector sheet 12 coated with the mixture 11 in a state in which the current collector sheet 12 is heated. A heating region 32 to be heated in the heating step includes at least a part of the uncoated region 13.

Description

Plate manufacturing method and device

[0001] The present disclosure relates to a method and an apparatus for manufacturing an electrode plate.

[0002] In batteries such as lithium-ion batteries, electrode plates are used in which a composite material containing an active material is applied to a current collector. When manufacturing the electrode plates, the composite material is applied to the current collector, dried, and then compressed by a press (Patent Document 1).

[0003] JP 2008-186704 A

[0004] In the manufacture of the electrode plate described above, the composite material is partially applied to the current collector sheet, forming coated and uncoated areas. If the current collector sheet is compressed in this state, wrinkles and / or breaks (also called edge cuts) may occur in the current collector sheet, mainly in the uncoated areas. This may cause a decrease in the performance of the electrode plate and even make it unusable as an electrode plate.

[0005] An object of the present disclosure is to realize a method and apparatus for manufacturing an electrode plate that can suppress the occurrence of wrinkles and breaks in the current collector sheet.

[0006] The electrode plate manufacturing method of the present disclosure includes a heating step of heating a part of a current collector sheet having a coated region coated with a composite material containing an active material and an uncoated region where the composite material is not coated, and a compressing step of compressing the heated current collector sheet. The heating region heated in the heating step includes at least a part of the uncoated region.

[0007] The electrode plate manufacturing apparatus of the present disclosure includes a heating unit that heats a portion of a current collector sheet coated with a composite material containing an active material, and a compression unit that compresses the current collector sheet coated with the composite material while the current collector sheet is heated. The current collector sheet has a coated region where the active material is coated and an uncoated region where the active material is not coated. The heating region that is heated by the heating unit includes at least a portion of the uncoated region.

[0008] According to the present disclosure, in the electrode plate manufacturing method and electrode plate manufacturing apparatus, the occurrence of wrinkles and / or breaks can be suppressed by performing the compression step in a state in which the uncoated area of ​​the current collector sheet is overheated.

[0009] FIG. 1 is a schematic plan view showing the structure of an electrode plate in which a composite containing an active material is applied to a current collector sheet. FIG. 2 is a cross-sectional view corresponding to FIG. 1. FIG. 3 is a schematic view showing an electrode plate manufacturing apparatus and manufacturing method, particularly the heating and compression steps. FIG. 4 is a view showing an example of heating a current collector sheet by laser heating. FIG. 5 is a view showing an example of heating a current collector sheet by a heat roll. FIG. 6 is a view showing an example of heating a current collector sheet by induction heating. FIG. 7 is a view showing an example of heating a rolled current collector sheet from the end in the width direction. FIG. 8 is a view showing an example of simultaneously performing the heating and compression steps using a compression roll equipped with a heating mechanism. FIG. 9 is a view showing several heating regions (examples and comparative examples) for a current collector sheet. FIG. 10 is a view showing examples of coated and uncoated regions on an electrode plate and the corresponding heated regions.

[0010] Hereinafter, embodiments will be described with reference to the accompanying drawings. The following description is merely an example and is not intended to be limiting. Furthermore, modifications can be made as appropriate within the scope of the present invention.

[0011] 1 and 2 are schematic plan and cross-sectional views showing an example of the configuration of an electrode plate 10 used in a lithium-ion battery or the like. As shown in FIG. 2, the electrode plate 10 has a configuration in which a composite material 11 containing an active material is applied to a current collector sheet 12. In the example of FIG. 2, the composite material 11 is applied to both sides of the current collector sheet 12, but it may be applied to only one side of the current collector sheet 12. Furthermore, an "electrode plate" is manufactured through a process of applying the composite material 11, a heating process, a compression process, and the like, which will be described below. In the following, the state of each stage during manufacturing, including the current collector sheet 12 and the applied composite material 11, will also be referred to as the "electrode plate 10."

[0012] 1 , the composite material 11 is applied to the current collector sheet 12 so as to leave uncoated regions 14. More specifically, the long current collector sheet 12 has uncoated regions 14 at both ends in the width direction, and is coated intermittently in the longitudinal direction, so that rectangular coated regions 13 are arranged side by side with the uncoated regions 14 sandwiched between them.

[0013] The current collector sheet 12 may be made of a metal foil such as aluminum foil or copper foil. The composite material 11 includes an active material such as a carbon material, a metal element, or a semi-metal element, and a binder. The composite material 11 is made into a paste-like slurry by adding, for example, water or an organic solvent, and is applied onto the current collector sheet 12 (application process). The layer of the composite material 11 is then dried.

[0014] In manufacturing the electrode plate 10, the composite material 11 is applied (and dried) onto the current collector sheet 12, and then the layer of composite material 11 is compression molded, as illustrated in FIG.

[0015] 3 is a diagram schematically illustrating a main part of an electrode plate manufacturing apparatus 20 according to the present disclosure. The electrode plate manufacturing apparatus 20 has a roll-to-roll configuration. That is, it includes an unwinding roll 21 around which an electrode plate 10 in the middle of manufacturing is wound, and a winding roll 22 that winds up the electrode plate 10 unwound from the unwinding roll 21. Between the unwinding roll 21 and the winding roll 22, the electrode plate 10 is compressed by a pair of compression rolls 23 (compression process).

[0016] The electrode plate 10 wound around the winding roll 22 is in a state in which the composite material 11 is applied to the current collector sheet 12 and then dried. After undergoing a compression step using a compression roll 23, the electrode plate 10 is wound around the winding roll 22.

[0017] Furthermore, a heating section 24 is provided closer to the unwinding roll 21 than the compression roll 23, so that a predetermined heating area of ​​the electrode plate 10 can be heated before the compression step.

[0018] When compression is performed by the compression roll 23 without heating, the current collector sheet 12 is likely to wrinkle and / or break, particularly in the uncoated region 14. This is because the current collector sheet 12 does not stretch sufficiently, and the effect of the force applied to the current collector sheet 12 during compression differs depending on whether or not the composite material 11 is present, and this is likely to be seen in the uncoated region 14. Since the current collector sheet 12 stretches differently in the coated region 13 and the uncoated region 14, wrinkles occur particularly in the uncoated region 14. Furthermore, the current collector sheet 12 is stretched excessively in the uncoated region 14, causing breakage (edge ​​cuts).

[0019] In contrast, if the heating area of ​​the collector sheet 12 is heated using the heating section 24 before the compression process using the compression roll 23, the collector sheet 12 made of metal foil becomes more easily stretchable, thereby suppressing the occurrence of wrinkles and / or breakage.

[0020] However, if the entire current collector sheet 12 (electrode plate 10) is heated, the tensile force of the roll-to-roll process may cause the current collector sheet 12 to stretch excessively, resulting in breakage, etc. Therefore, heating by the heating unit 24 is performed on a partial region of the current collector sheet 12, i.e., a heating region including the uncoated region 14.

[0021] When copper foil is used as the current collector sheet 12, the thickness thereof is preferably, for example, 5 μm or more and 20 μm or less. When aluminum foil is used as the current collector sheet 12, the thickness thereof is preferably, for example, 5 μm or more and 30 μm or less. In either case of copper foil or aluminum foil, the heating temperature is preferably 150° C. or more and 400° C. or less. Performing the compression step in a state heated within this temperature range makes the current collector sheet 12 more extensible, thereby suppressing wrinkling and / or breakage, and also makes it possible to avoid breakage due to excessive softening.

[0022] Fig. 4 is a diagram showing a heating region 32 in the electrode plate 10 and an example of a heating method. In Fig. 4, the electrode plate 10 is being wound from left to right in the drawing (as shown in Fig. 3), and in the process, it is compressed by a compression roll 23. Note that Fig. 4 shows only one of a pair of compression rolls 23.

[0023] Furthermore, before the wound electrode plate 10 reaches the compression roll 23, a heating area 32 is heated by a laser heating device 31 provided as a specific example of the heating unit 24. In this example, the heating area 32 is located at both ends in the width direction of the electrode plate 10. This heats the uncoated area 14 located in this area, thereby suppressing the occurrence of wrinkles and / or breakage during the compression process.

[0024] 5 shows another specific example of the heating unit 24, in which a heating area 32 of the electrode plate 10 is heated by a heat-generating heat roll 33. Heat generation may also be achieved by using, for example, an electric heating wire.

[0025] Furthermore, FIG. 6 shows, as another specific example of the heating unit 24, heating by an induction heating device 34 that inductively heats the current collector sheet 12 made of metal foil.

[0026] These devices may be used as the heating section 24 that heats the uncoated region 14 .

[0027] (Another Example of Heating Method) In the above, as shown in Fig. 3, a heating step by the heating unit 24 and a subsequent compression step by the compression roll 23 are performed while the electrode plate 10 is being wound from the unwinding roll 21 onto the winding roll 22. However, the method for performing the heating step is not limited to this. As an example, Fig. 7 shows an example in which the uncoated region 14 of the electrode plate 10 in a rolled state is heated.

[0028] The electrode plate 10 in Fig. 7 is in a state where the composite material 11 is applied to the current collector sheet 12, dried, and then wound around a roll. As shown in Fig. 1, the electrode plate 10 has uncoated regions 14 at least at both ends in the width direction. Therefore, since both ends in the width direction of the electrode plate 10 are located on the bottom surface of the approximately cylindrical roll, the uncoated regions 14 in those locations can be heated by heating the bottom surface of the roll. Laser heating, induction heating, etc. can be used for heating.

[0029] After such heating, a compression process is performed using, for example, an apparatus similar to that shown in FIG. 2 (but excluding the heating unit 24). In this case, the effect of suppressing the occurrence of wrinkles and / or breakage is also achieved. Furthermore, compared to the case where heating is performed while the electrode plate 10 is being wound, as shown in FIG. 3, etc., sufficient heating can be performed in the rolled state. Depending on the required level of heating, such a method is desirable in order to more reliably achieve the effect of suppressing wrinkles and / or breakage.

[0030] Next, FIG. 8 shows yet another example. In the example of FIG. 8, similar to FIGS. 3 to 5, the compression process is performed while the electrode plate 10 is moving from the unwinding roll 21 to the winding roll 22. However, in this case, instead of the normal compression roll 23 shown in FIG. 3, a compression roll 23a having a heat generating mechanism 35 is used. This allows the heating process and the compression process to be performed simultaneously. In this method, it is not necessary to provide a heating unit 24 separate from the compression roll 23. Therefore, it is possible to avoid increasing the size of the electrode plate 10 manufacturing equipment.

[0031] (Heated Area) FIGS. 9A to 9D show the heated areas of the electrode plate 10. FIG.

[0032] 9A shows an electrode plate 10 in which a composite material 11 is applied to a current collector sheet 12, with uncoated regions 14 located at both ends in the width direction (the left-right direction in the drawing) and a coated region 13 located therebetween. Here, we consider the prevention of wrinkling and / or breakage in the uncoated regions 14 at both ends in the width direction.

[0033] In this case, as shown in B, the effect of the present disclosure can be achieved by performing the heating process with the uncoated region 14 as the heating region 32. However, it is possible that heating may be insufficient near the boundary between the uncoated region 14 and the coated region 13. Furthermore, precise control is required to accurately heat only the uncoated region 14, and it is possible that the position of the heating region 32 may be shifted, resulting in the creation of unheated regions in the uncoated region 14. In such cases, the effect of suppressing wrinkling and / or breakage is reduced.

[0034] Therefore, as shown in C, the heating region 32 may be arranged to include the uncoated region 14 and the coated region 13 adjacent to the uncoated region 14. In this way, the uncoated region 14 is sufficiently heated up to the vicinity of the boundary with the coated region 13. Furthermore, even if the heating region 32 is misaligned with respect to the electrode plate 10, the uncoated region 14 is included in the heating region 32, and the occurrence of unheated regions is suppressed. Therefore, the effect of suppressing wrinkles and / or breakage is more reliably achieved.

[0035] D shows a case where the entire electrode plate 10, including the coated region 13 and the uncoated region 14, is used as the heated region 32. In this case, the entire current collector sheet 12 becomes soft, which may cause breakage or excessive elongation due to the tensile force of the roll-to-roll process in the process shown in FIG.

[0036] Therefore, it is desirable to arrange the heating area 32 at least in the uncoated area 14 as in B, and it is more desirable to arrange the heating area 32 as in C, which includes the uncoated area 14 and the coated area 13 adjacent to it.

[0037] It is desirable that the area of ​​the coated region 13 included in the heated region 32 be 50% or less of the entire coated region 13. In this way, the uncoated region 14 can be reliably heated and excessive stretching of the current collector sheet 12 can be suppressed.

[0038] (Another Example of Arrangement of Uncoated Regions) FIG. 10 shows another example of the arrangement of the coated regions 13 and uncoated regions 14 on the electrode plate 10 and the corresponding heated regions 32. In FIG.

[0039] 10 , a plurality of stripe-shaped coated regions 13 are provided so as to extend in the longitudinal direction of the electrode plate 10. In the width direction, uncoated regions 14 are arranged at both ends and between each of the coated regions 13. In such a case, by arranging the heating region 32 so as to include the uncoated regions 14 extending in the longitudinal direction, it is possible to suppress the occurrence of wrinkles and / or breakage in each of the uncoated regions 14.

[0040] To arrange the heating regions 32 in this manner, for example, in FIGS. 4 to 6, the heating sections 24 may be provided on the inside in addition to both ends in the width direction.

[0041] 1, in addition to the uncoated regions 14 located at both ends in the width direction, there are uncoated regions 14 extending in the width direction between the rectangular coated regions 13 aligned in the longitudinal direction. In this case as well, wrinkles and / or breaks during the compression process occur mainly in the uncoated regions 14 at both ends in the width direction. Therefore, the effects of the present disclosure can be achieved by heating the uncoated regions 14 at both ends in the width direction of the electrode plate 10, as shown in FIGS. 4 to 6, etc.

[0042] The above-described embodiments may be modified in form and detail without departing from the spirit of the claims. Furthermore, the contents of the embodiments may be combined and substituted as appropriate as long as the functions of the subject matter of the present disclosure are not impaired.

[0043] INDUSTRIAL APPLICABILITY The present disclosure is useful as a method and apparatus for manufacturing an electrode plate, since it can suppress the occurrence of wrinkles and / or breaks in a current collector sheet during the manufacture of an electrode plate.

[0044] REFERENCE SIGNS LIST 10 Electrode plate 11 Composite material 12 Current collector sheet 13 Coated area 14 Uncoated area 20 Electrode plate manufacturing device 21 Roll 22 Roll 23 Compression roll 23a Heat roll 24 Heating section 31 Laser heating device 32 Heating area 33 Heat roll 34 Induction heating device 35 Heating mechanism

Claims

1. A method for manufacturing an electrode plate, comprising: a heating step of heating a portion of a current collector sheet having a coated region coated with a composite material containing an active material and an uncoated region where the composite material is not coated; and a compressing step of compressing the current collector sheet coated with the composite material while the current collector sheet is in a heated state, wherein the heating region heated in the heating step includes at least a portion of the uncoated region.

2. A method for manufacturing an electrode plate according to claim 1, wherein the heating region includes the coating region adjacent to the heating region, and the area of ​​the coating region included in the heating region is 50% or less of the area of ​​the entire coating region.

3. The electrode plate manufacturing method according to claim 1, wherein the heated area is the uncoated area.

4. The electrode plate manufacturing method according to claim 1, wherein the heating step is performed by laser heating.

5. The electrode plate manufacturing method according to claim 1, wherein the heating step involves heating using a heat roller that generates heat.

6. The electrode plate manufacturing method according to claim 1, wherein the heating step is performed by induction heating.

7. A method for manufacturing an electrode plate according to claim 1, wherein the uncoated region is provided at least at the end in the width direction of the current collector sheet, and the method further comprises, after the coating step, a winding step of winding up the current collector sheet coated with the composite into a roll, and the heating step is carried out by heating the end in the width direction of the current collector sheet in a rolled state.

8. A method for manufacturing an electrode plate according to claim 1, wherein the uncoated area is provided at least at the end of the collector sheet in the width direction, and the heating step and the compression step are carried out simultaneously using a compression roll equipped with a heating mechanism.

9. An electrode plate manufacturing apparatus comprising: a heating unit that heats a portion of a current collector sheet coated with a composite material containing an active material; and a compression unit that compresses the current collector sheet coated with the composite material while the current collector sheet is in a heated state; wherein the current collector sheet has a coated region where the active material is coated and an uncoated region where the active material is not coated; and the heating region heated by the heating unit includes at least a portion of the uncoated region.

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