Manufacturing method of electrode sheet

Abstract

To provide a technique capable of improving manufacturing quality of an electrode sheet for batteries.SOLUTION: A method of manufacturing an electrode sheet includes: a coating step of applying an active material paste on a surface of a long metal sheet while conveying the metal sheet; and a drying step of drying the active material paste on the metal sheet while conveying, in a drying furnace, the metal sheet on which the active material paste is applied. In the drying furnace, hot air is blown along a conveyance direction of the metal sheet and light is radiated from at least one light source to the active material paste on the metal sheet. By radiation of the light, temperatures of the active material paste become higher than temperatures in the drying furnace.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a method for producing an electrode sheet for a battery.

[0002] Patent Document 1 describes a method for manufacturing an electrode sheet, in which a metal sheet coated with an active material paste is transported through a drying furnace maintained at a high temperature, thereby drying the active material paste on the metal sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-29256 A Summary of the Invention [Problem to be solved by the invention]

[0004] In order to dry the active material paste in a short time, it is necessary to increase the temperature in the drying oven. However, the temperature in the drying oven tends to be uneven, and it is difficult to properly control the temperature in the drying oven. As a result, there is a risk that the manufacturing quality of the electrode sheet will be reduced due to unintended thermal deformation of the metal sheet. This specification provides a technology that can improve the manufacturing quality of the electrode sheet by avoiding such problems. [Means for solving the problem]

[0005] The technology disclosed in this specification is embodied in a manufacturing method for an electrode sheet. This manufacturing method includes a coating step of coating an active material paste on a surface of a long metal sheet while transporting the metal sheet, and a drying step, which is carried out in parallel with the coating step, of drying the active material paste on the metal sheet while transporting the metal sheet coated with the active material paste in a drying oven. In the drying oven, hot air is blown along the transport direction of the metal sheet, and light is irradiated from at least one light source onto the active material paste on the metal sheet. By irradiating the light, the temperature of the active material paste becomes higher than the temperature in the drying oven.

[0006] In the above-mentioned manufacturing method, the supply of hot air into the drying oven and the irradiation of light onto the active material paste are combined, so that the temperature of the active material paste can be selectively increased without excessively increasing the temperature inside the drying oven. This makes it easy to control the temperature of the active material paste, and allows the active material paste to be dried uniformly in a short time. In addition, since the hot air supplied into the drying oven flows along the conveying direction of the metal sheet, the hot air does not strongly hit the active material paste. This makes it possible to maintain the temperature inside the drying oven at a suitable temperature for drying without unnecessarily affecting the active material paste, and to exhaust water vapor generated by drying. [Brief description of the drawings]

[0007] [Figure 1] 1 shows a schematic configuration of an electrode sheet manufacturing apparatus 10 used in the examples. [Diagram 2] FIG. 2 is a side view showing the configuration of a drying device 16. [Diagram 3] 2 is a diagram showing an irradiated area 20a and a non-irradiated area 20b of laser light L in a plan view. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In one embodiment of the present technology, the at least one light source may include a plurality of light sources arranged along the conveying direction of the metal sheet. That is, the number of light sources is not limited to one, and a plurality of light sources may be used depending on, for example, a target drying time. In addition, by using a plurality of light sources, each light source can be made smaller, and the distance from each light source to the metal sheet can also be shortened. This allows the drying oven to be made smaller.

[0009] In one embodiment of the present technology, in the drying step, the output of the at least one light source may be adjusted according to the temperature of the metal sheet (including the temperature of the active material paste on the metal sheet), thereby allowing the temperature of the active material paste to be appropriately controlled and the active material paste to be dried uniformly in a short time.

[0010] In one embodiment of the present technology, in the drying process, the temperature, the air volume, or both of the hot air supplied into the drying oven may be adjusted so that the temperature in the drying oven becomes a predetermined target temperature. In this case, the predetermined target temperature is not limited to a specific temperature, and may be a temperature range having a certain width.

[0011] In the above embodiment, the predetermined target temperature may be 80° C. or more and 150° C. or less. If the temperature in the drying oven falls below 80° C., the amount of saturated steam in the drying oven becomes insufficient, and the efficiency of drying decreases. On the other hand, if the temperature in the drying oven exceeds 150° C., the metal sheet is affected by the temperature, and the manufacturing quality of the electrode sheet may decrease. EXAMPLES

[0012] A manufacturing method of the embodiment will be described with reference to the drawings. The manufacturing method of the embodiment is for manufacturing an electrode sheet for a battery, and is carried out using a manufacturing apparatus 10 shown in FIG. 1. The battery referred to here is not particularly limited, but may be, for example, a lithium ion battery. The electrode sheet may be an electrode sheet for a positive electrode or an electrode sheet for a negative electrode.

[0013] As shown in FIG. 1, a manufacturing apparatus 10 includes a conveying device 12, a coating device 14, and a drying device 16. The conveying device 12 conveys a long metal sheet 2 along a predetermined conveying path. The metal sheet 2 is made of, but is not limited to, copper or aluminum. The surface of the metal sheet 2 may be carbon coated. Note that the direction X in the figure indicates the conveying direction of the metal sheet 2 by the conveying device 12.

[0014] The coating device 14 is a device that applies an active material paste 4 to the surface of the metal sheet 2. The active material paste 4 is a paste that contains at least an active material, and its specific configuration is not particularly limited. The coating device 14 is disposed on the transport path of the metal sheet 2 by the transport device 12, and applies the active material paste 4 to the surface of the metal sheet 2 being transported. The active material paste 4 is widely coated on the surface of the metal sheet 2 except for both end portions (see FIG. 3, etc.).

[0015] The drying device 16 is a device for applying the active material paste 4. The drying device 16 is also disposed on the path along which the metal sheet 2 is conveyed by the conveying device 12. The drying device 16 is located downstream of the coating device 14 in the conveying direction X of the metal sheet 2, and quickly dries the active material paste 4 applied to the surface of the metal sheet 2.

[0016] 2, the drying device 16 includes a drying furnace 18 and a plurality of light sources 20 provided in the drying furnace 18. The metal sheet 2 sent out from the coating device 14 is carried into the drying furnace 18. The drying device 16 dries the active material paste 4 on the metal sheet 2 while the metal sheet 2 is transported inside the drying furnace 18. The specific configuration of the drying furnace 18 is not particularly limited, but it is preferable that the drying furnace 18 has thermal insulation properties in order to maintain the internal temperature.

[0017] The multiple light sources 20 irradiate laser light L onto the metal sheet 2 being transported through the drying furnace 18. The laser light L is irradiated onto the active material paste 4 on the metal sheet 2, heating the active material paste 4. The multiple light sources 20 are not limited to laser light L, and may be any light source that irradiates light capable of heating the active material paste 4. Although not particularly limited, the multiple light sources 20 are arranged along the transport direction X of the metal sheet 2. As a result, the multiple irradiation ranges 20a into which light is irradiated by the multiple light sources 20 are also arranged along the transport direction X.

[0018] As shown in Figs. 2 and 3, a certain interval is provided between the multiple irradiation areas 20a. As a result, a non-irradiation area 20b, to which the laser light L is not irradiated, is provided between two adjacent irradiation areas 20a. With this configuration, the active material paste 4 applied to the metal sheet 2 is intermittently irradiated with the laser light L as the metal sheet 2 is transported. The metal sheet 2 and the active material paste 4 heated in the irradiation area 20a of the laser light L are cooled while passing through the non-irradiation area 20b, thereby suppressing an excessive temperature rise of the metal sheet 2. Note that, with respect to the width direction of the metal sheet 2, the position and size of the irradiation area 20a coincide with the position and size of the active material paste 4 applied to the metal sheet 2.

[0019] As shown in FIG. 2, a duct 22 is connected to the drying furnace 18. The duct 22 supplies hot air B into the drying furnace 18. An outlet 22a for the hot air B connected to the duct 22 is located at the upstream end of the conveying direction X and is oriented to blow out the hot air B toward the downstream side of the conveying direction X. As a result, inside the drying furnace 18, the hot air B is blown along the conveying direction X. The temperature of the hot air B is not particularly limited. However, the temperature inside the drying furnace 18 may be 80° C. or more and 150° C. or less, and the temperature of the hot air B may be a temperature corresponding thereto.

[0020] The drying oven 18 is provided with an oven temperature sensor 26 and a plurality of sheet temperature sensors 24. The oven temperature sensor 26 can measure the temperature inside the drying oven 18. This makes it possible to adjust the temperature or the amount of hot air B supplied into the drying oven 18 so that the temperature inside the drying oven 18 becomes a predetermined target temperature (for example, any temperature or temperature range not less than 80° C. and not more than 150° C. as described above). This adjustment may be performed by an operator or automatically by a control device. Although not particularly limited, the oven temperature sensor 26 is provided near the air outlet 22a.

[0021] The sheet temperature sensor 24 measures the temperature of the metal sheet 2. Although not particularly limited, the sheet temperature sensor 24 is a non-contact type temperature sensor and measures the temperature of the metal sheet 2 from its back surface. The sheet temperature sensors 24 are provided one for each of the irradiation ranges 20a to which the laser light L is irradiated. With this configuration, the output of the light source 20 can be adjusted according to the temperature of the metal sheet 2. This adjustment may be performed by an operator or automatically by a control device. The number of the sheet temperature sensors 24 is not particularly limited. The drying device 16 only needs to include at least one sheet temperature sensor 24 regardless of the number of light sources 20. The sheet temperature sensor 24 may measure the temperature of the metal sheet 2 from its front surface, that is, measure the temperature of the active material paste 4 on the metal sheet 2.

[0022] With the above-described configuration, in the method for manufacturing an electrode sheet using the manufacturing apparatus 10, a coating step is carried out in which an active material paste 4 is applied to the surface of the long metal sheet 2 while the metal sheet 2 is being transported. In parallel with the coating step, a drying step is carried out in which the active material paste 4 on the metal sheet 2 is dried. The drying step is carried out in a drying furnace 18. In the drying furnace 18, hot air is blown along the transport direction X of the metal sheet 2, and laser light L is irradiated from a plurality of light sources 20 to the active material paste 4 on the metal sheet 2. The temperature of the active material paste 4 becomes higher than the temperature in the drying furnace 18 by the irradiation of the laser light L.

[0023] In the above-mentioned manufacturing method, by combining the supply of hot air B into the drying furnace 18 and the irradiation of the laser light L onto the active material paste 4, the temperature of the active material paste 4 can be selectively increased without excessively increasing the temperature inside the drying furnace 18. This makes it easy to control the temperature of the active material paste 4, and allows the active material paste 4 to be dried uniformly in a short time. In addition, since the hot air B supplied into the drying furnace 18 flows along the conveying direction X of the metal sheet 2, the hot air B does not strongly impinge on the active material paste 4. This makes it possible to maintain the temperature inside the drying furnace 18 at a suitable temperature for drying and to exhaust water vapor generated by drying without giving unnecessary effects (for example, local temperature changes) to the active material paste 4. [Explanation of symbols]

[0024] 2: metal sheet, 4: active material paste, 10: manufacturing device, 12: conveying device, 14: coating device, 16: drying device, 18: drying furnace, 20: light source, 20a: irradiated area, 20b: non-irradiated area, 22: furnace temperature sensor, 24: sheet temperature sensor, L: laser light, B: hot air

Claims

1. A method for producing an electrode sheet, comprising: a coating step of coating a surface of a long metal sheet with an active material paste while conveying the metal sheet; a drying step, which is carried out in parallel with the coating step, of drying the active material paste on the metal sheet while transporting the metal sheet on which the active material paste has been applied in a drying furnace; Equipped with In the drying oven, hot air is blown along a conveying direction of the metal sheet, and light is irradiated from at least one light source onto the active material paste on the metal sheet; In the drying step, the output of the at least one light source is adjusted according to the temperature of the metal sheet, and at the same time, the temperature, the amount of air, or both of the hot air supplied into the drying oven are adjusted so that the temperature in the drying oven becomes a predetermined target temperature, thereby maintaining the temperature of the active material paste at a temperature higher than the temperature in the drying oven. Manufacturing method.

2. The manufacturing method according to claim 1 , wherein the at least one light source includes a plurality of light sources arranged along a conveying direction of the metal sheet.

3. The method of claim 1 , wherein the predetermined target temperature is greater than or equal to 80° C. and less than or equal to 150° C.

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