Electrode manufacturing method and power storage device manufacturing method

Abstract

To provide a method for manufacturing an electrode and a power storage device in which cracking of an active material layer is suppressed.SOLUTION: In a manufacturing method of a bipolar electrode 20, in a drying process in which a slurry applied to a current collector 21 is radiantly heated to form a positive electrode active material layer 22 and a negative electrode active material layer 23, the humidity of an uncoated region T2 of the current collector 21 where the slurry is not applied is made higher than the humidity of the coated region T1 of the current collector 21 where the slurry is applied.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an electrode and a method for manufacturing an electricity storage device. [Background technology]

[0002] Patent Document 1 discloses a technique in which a coating film is irradiated with far-infrared rays having a wavelength that is highly absorbent for organic solvents, thereby evaporating the organic solvent from the entire coating film and bringing the coating film to a dry state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-63495 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electrode and the electricity storage device, it is preferable to suppress cracking of the active material layer.

[0005] An object of the present invention is to provide a method for manufacturing an electrode and an electricity storage device in which cracking of the active material layer is suppressed. [Means for solving the problem]

[0006] In the electrode manufacturing method according to claim 1, in a drying step in which a slurry applied to a current collector is radiantly heated to form an active material layer, the humidity of an uncoated area of the current collector that has not been coated with the slurry is made higher than the humidity of a coated area of the current collector that has been coated with the slurry.

[0007] In the electrode manufacturing method according to claim 1, the humidity of the uncoated area of the current collector, where the slurry is not coated, is set higher than the humidity of the coated area of the current collector, so that the humidity of the uncoated area of the current collector is higher than that of the coated area. This prevents the slurry from drying out at the edge of the coated area. As a result, cracking of the active material layer can be suppressed.

[0008] A method for producing an electrode according to a second aspect of the present invention is the method for producing an electrode according to the first aspect, wherein in the drying step, air is blown to the uncoated region at a higher humidity than to the coated region.

[0009] In the electrode manufacturing method according to claim 2, by blowing air at a higher humidity to the uncoated area than to the coated area, the uncoated area of the current collector has a higher humidity than the coated area. This prevents the slurry from drying out at the edge of the coated area. As a result, cracking of the active material layer can be suppressed.

[0010] The electrode manufacturing method according to claim 3 is the electrode manufacturing method according to claim 2, wherein the air blown to the uncoated region is exhausted to the side of the current collector.

[0011] In the electrode manufacturing method according to claim 3, the air blown to the uncoated area is exhausted to the side of the current collector, thereby preventing the air blown to the uncoated area from flowing into the coated area. This maintains a balance between the drying speed of the slurry at the edge of the coated area and the drying speed of the slurry at the center of the coated area. As a result, cracking of the active material layer can be prevented.

[0012] The method for manufacturing an energy storage device according to claim 4 includes a cutting step of cutting electrodes manufactured by the manufacturing method according to any one of claims 1 to 3, a sealing step of sealing the periphery of the cut electrodes, and a welding step of stacking the sealed electrodes and welding their outer surfaces.

[0013] According to the method for producing an electricity storage device according to claim 4, it is possible to produce an electricity storage device in which cracking of the active material layer is suppressed. [Effects of the Invention]

[0014] As described above, according to the method for manufacturing an electrode and an electricity storage device according to the present invention, cracking of the active material layer can be suppressed. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view schematically illustrating an electricity storage device according to an embodiment. [Figure 2] 1 is a perspective view schematically showing an electrode manufacturing apparatus according to an embodiment. [Figure 3] 3 is a cross-sectional view schematically showing the electrode manufacturing apparatus according to the embodiment, showing the cross section AA of FIG. 2. FIG. [Figure 4] FIG. 3 is a flowchart showing a method for manufacturing an electricity storage device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, a power storage device according to an embodiment will be described with reference to the drawings. The power storage device according to the embodiment is mounted on a vehicle such as an electric vehicle or a hybrid vehicle and used as an on-board power source. In each drawing, an arrow UP indicates the upper side in the vertical direction of the power storage device 10, an arrow LH indicates the left side in the horizontal direction of the power storage device 10, an arrow W indicates the width direction W of the bipolar electrode 20, and an arrow R indicates the transport direction R of the current collector 21. The top of the power storage device 10 coincides with the top of the vehicle in which the power storage device 10 is mounted.

[0017] [Configuration of Power Storage Device 10] 1, the power storage device 10 is formed in the shape of a rectangular plate with its thickness direction aligned with the vertical direction of the vehicle. The power storage device 10 is a so-called bipolar battery, and is, for example, a secondary battery such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery.

[0018] The power storage device 10 includes a laminate 12, a sealing body 28, and an electrolyte (not shown). The laminate 12 is configured by stacking a plurality of bipolar electrodes (an example of an electrode) 20 and a plurality of separators 25 in a stacking direction D.

[0019] (Bipolar electrode 20) The bipolar electrode 20 includes a current collector 21, a positive electrode active material layer 22, and a negative electrode active material layer .

[0020] The current collector 21 is formed in a rectangular plate shape with its thickness oriented in the vertical direction of the vehicle. The current collector 21 is made of a metal foil made of, for example, copper or aluminum.

[0021] The positive electrode active material layer 22 is formed in the shape of a rectangular plate with its thickness direction aligned in the vertical direction of the vehicle. The positive electrode active material layer 22 is formed by coating one surface (upper surface) in the vertical direction of the current collector 21. The positive electrode active material layer 22 is formed inside the outer edge of the current collector 21. The positive electrode active material layer 22 contains a positive electrode active material (for example, a lithium-containing composite oxide) that can absorb and release charge carriers such as lithium ions.

[0022] The negative electrode active material layer 23 is formed in the shape of a rectangular plate with its thickness direction aligned in the vertical direction of the vehicle. The negative electrode active material layer 23 is formed by coating on the other surface (lower surface) in the vertical direction of the current collector 21. The negative electrode active material layer 23 is formed inside the outer edge of the current collector 21. The negative electrode active material layer 23 contains a negative electrode active material (for example, a carbon-based active material such as graphite or hard carbon) that can absorb and release charge carriers such as lithium ions.

[0023] (Separator 25) The separator 25 is formed in the shape of a rectangular plate with its thickness direction aligned with the vehicle vertical direction. The separator 25 is disposed between adjacent bipolar electrodes 20 in the stacking direction D. The separator 25 isolates adjacent bipolar electrodes 20 to prevent electrical short circuits between the electrodes. The positive electrode active material layer 22 and the negative electrode active material layer 23 are impregnated with an electrolyte.

[0024] (Sealing body 28) The sealing body 28 is formed in a frame shape so as to surround the periphery of the laminate 12. The sealing body 28 can be formed into a frame shape, for example, by placing molten thermoplastic resin on the periphery of the laminate 12 and cooling it. The sealing body 28 holds the peripheries of the bipolar electrodes 20 and the separators 25 and seals the spaces S formed between the bipolar electrodes 20.

[0025] [Method of manufacturing the electricity storage device 10] 2, the energy storage device 10 is manufactured through an electrode manufacturing process, a lamination process, and a welding process. The electrode manufacturing process includes a coating process, a drying process, a cutting process, and a sealing process.

[0026] The coating step and drying step will be described with reference to a method for forming the positive electrode active material layer 22 on one vertical surface of the current collector 21. The method for forming the negative electrode active material layer 23 on the other vertical surface of the current collector 21 can be the same as the method for forming the positive electrode active material layer 22.

[0027] (Coating process) In the coating process of step S101, as shown in Fig. 3, current collector 21 formed in a long strip shape is unwound in the longitudinal direction and transported in transport direction R. Then, slurry for forming positive electrode active material layer 22 is supplied from slurry supply device 31 to one surface in the vertical direction of current collector 21 being transported.

[0028] In this case, the region to which the slurry is supplied is referred to as a coated region T1, and the region to which the slurry is not supplied is referred to as an uncoated region T2. In this embodiment, the coated region T1 is a region including the center of the current collector 21 in the width direction W, and the uncoated regions T2 are regions at both ends (both edges) of the current collector 21 in the width direction W.

[0029] The slurry may be supplied intermittently in the longitudinal direction of the current collector 21 to form coated and uncoated regions aligned in the longitudinal direction of the current collector 21.

[0030] (drying process) In the drying process of step S102, the current collector 21 supplied with the slurry for forming the positive electrode active material layer 22 is transported in the transport direction R. Then, the current collector 21 being transported is subjected to radiant heating (for example, irradiation with laser light or an infrared heater) by the drying device 32 to dry the slurry, thereby forming the positive electrode active material layer 22.

[0031] 4, air is supplied to the coated region T1 and the uncoated region T2 by the air blower 40. In other words, the current collector 21 on which the slurry is disposed is radiantly heated by the drying device 32, and air is supplied by the air blower 40.

[0032] In addition, air may be supplied by the blower 40 before the current collector 21 to which the slurry has been supplied is radiantly heated by the dryer 32, or air may be supplied by the blower 40 after the current collector 21 to which the slurry has been supplied is radiantly heated by the dryer 32.

[0033] Here, the air blower 40 has a first air blower 41 and a second air blower 42. The first air blower 41 is disposed at the center of the current collector 21 in the width direction W. The first air blower 41 is configured to supply air with a lower humidity than the second air blower 42.

[0034] The second air blowers 42 are disposed at both ends of the current collector 21 in the width direction W. The second air blowers 42 are configured to supply air with a higher humidity than the first air blower 41. As a result, air is blown to the uncoated region T2 at a higher humidity than the coated region T1. Therefore, the humidity of the uncoated region T2 is made higher than the humidity of the coated region T1.

[0035] The air sent by the blower 40 is exhausted by the exhaust device 50. The exhaust device 50 includes a first exhaust device 51 and a second exhaust device 52.

[0036] The first exhaust device 51 is disposed at approximately the same position as the air blower 40 in the longitudinal direction of the current collector 21, and on the outside in the width direction W of the current collector 21. The first exhaust device 51 exhausts the air sent by the air blower 40 to the outside (lateral side) in the width direction W of the current collector 21.

[0037] The second exhaust device 52 is disposed below the current collector 21 at approximately the same position as the blower 40 in the longitudinal direction of the current collector 21. The second exhaust device 52 exhausts the air that has been exhausted to the outside (lateral side) of the width direction W of the current collector 21 below the current collector 21. The air exhausted by the second exhaust device 52 may be supplied to the blower 40.

[0038] (cutting process) In the cutting step of step S103, the current collector 21 on which the positive electrode active material layer 22 and the negative electrode active material layer 23 are formed is cut in the width direction W into individual sheets.

[0039] (Sealing process) In the sealing step S104, the periphery of the cut current collector 21 is sealed with, for example, a thermoplastic resin, thereby forming the bipolar electrode 20.

[0040] (Lamination process) In the stacking step of step S105, the bipolar electrodes 20 and the separators 25 are stacked alternately in the stacking direction D to form the stack 12.

[0041] (Welding process) In the welding process of step S106, for example, molten thermoplastic resin is placed on the periphery of the laminate 12 and heat-welded to form the sealing body 28. In other words, in the welding process, the outer surface of the laminate 12 is heat-welded to form the sealing body 28. In this way, the energy storage device 10 is formed.

[0042] [Effect] Incidentally, in the drying process, when the slurry coated on the current collector 21 is radiantly heated, the uncoated region T2 where the slurry is not coated is overheated. The heat from the overheated uncoated region T2 is transferred to the coated region T1 of the current collector 21. Therefore, the drying of the slurry at the edge of the coated region T1 is accelerated compared to the slurry in the center of the coated region T1. When the slurry is dried rapidly, steam is rapidly released from the holes (pores) formed in the positive electrode active material layer 22 and the negative electrode active material layer 23. As a result, cracks may occur in the positive electrode active material layer 22 and the negative electrode active material layer 23 formed on the edges of the coated region T1.

[0043] In the manufacturing method of the bipolar electrode 20 according to the embodiment, in the drying process in which the slurry applied to the current collector 21 is radiantly heated to form the positive electrode active material layer 22 and the negative electrode active material layer 23, the humidity of the uncoated region T2 of the current collector 21, where the slurry has not been applied, is made higher than the humidity of the coated region T1 of the current collector 21, where the slurry has been applied (see FIG. 4).

[0044] By making the humidity of the uncoated region T2 of the current collector 21, which is not coated with the slurry, higher than the humidity of the coated region T1 of the current collector 21, the uncoated region T2 of the current collector 21 has a higher humidity than the coated region T1. This prevents the slurry from drying at the edge of the coated region T1. As a result, cracking of the positive electrode active material layer 22 and the negative electrode active material layer 23 can be prevented.

[0045] In the method for manufacturing the bipolar electrode 20 according to the embodiment, in the drying step, air is blown to the uncoated region T2 at a higher humidity than that to the coated region T1 (see FIG. 4).

[0046] By blowing air to the uncoated region T2 at a higher humidity than the coated region T1, the uncoated region T2 of the current collector 21 has a higher humidity than the coated region T1. This prevents the slurry from drying at the edge of the coated region T1. As a result, cracks in the positive electrode active material layer 22 and the negative electrode active material layer 23 can be prevented.

[0047] In the method for manufacturing the bipolar electrode 20 according to the embodiment, the air blown to the uncoated region T2 is exhausted to the side of the current collector 21 (see FIG. 4).

[0048] By discharging the air blown to the uncoated region T2 to the side of the current collector 21, the air blown to the uncoated region T2 is prevented from flowing into the coated region T1. This maintains a balance between the drying speed of the slurry at the edge of the coated region T1 and the drying speed of the slurry at the center of the coated region T1. As a result, cracking of the positive electrode active material layer 22 and the negative electrode active material layer 23 can be suppressed.

[0049] The manufacturing method of the energy storage device 10 according to the embodiment includes a cutting process for cutting the bipolar electrodes 20, a sealing process for sealing the peripheries of the cut bipolar electrodes 20, and a welding process for stacking the sealed bipolar electrodes 20 and welding the outer peripheral surfaces (see FIG. 2).

[0050] This makes it possible to manufacture an electricity storage device 10 in which cracking of the positive electrode active material layer 22 and the negative electrode active material layer 23 is suppressed.

[0051] The manufacturing methods of the electrode and the electricity storage device have been described above based on the embodiments. However, the specific configurations are not limited to these embodiments, and design changes are permitted as long as they do not deviate from the gist of the invention according to the claims.

[0052] In the embodiment, an example has been shown in which air is blown to the uncoated area T2 at a higher humidity than the coated area T1, thereby making the humidity of the uncoated area T2 higher than the humidity of the coated area T1. However, the humidity of the uncoated area T2 may be made higher than the humidity of the coated area T1 by providing an enclosure surrounding the uncoated area T2. Alternatively, air may be blown to the uncoated area T2 at a higher humidity than the coated area T1, and an enclosure may be provided to further surround the uncoated area T2.

[0053] In the embodiment, an example has been shown in which the electrode is a bipolar electrode 20. However, the electrode is not limited to this form, and may be a monopolar electrode.

[0054] In the embodiment, an example has been shown in which an electrolyte solution is accommodated inside the power storage device 10. However, the power storage device may be an all-solid-state battery. [Explanation of symbols]

[0055] 10. Energy storage device 20 Bipolar electrode (example of electrode) 21 Current collector 22 Positive electrode active material layer (active material layer) 23 Negative electrode active material layer (active material layer) T1 Coating area T2 Uncoated area

Claims

1. In a drying step in which the slurry applied to the current collector is radiantly heated to form an active material layer, The humidity of an uncoated region of the current collector that has not been coated with the slurry is set higher than the humidity of a coated region of the current collector that has been coated with the slurry. Electrode manufacturing method.

2. In the drying step, Air is blown to the uncoated area at a higher humidity than the coated area. A method for manufacturing the electrode according to claim 1.

3. The air blown to the uncoated area is exhausted to the side of the current collector. The method for manufacturing the electrode according to claim 2 .

4. a cutting step of cutting the electrode manufactured by the manufacturing method according to any one of claims 1 to 3; a sealing step of sealing the periphery of the cut electrode; a welding step of stacking the sealed electrodes and welding their outer circumferential surfaces; A method for manufacturing an electricity storage device comprising:

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