JP7655291B2 - Manufacturing method of electrode sheet - Google Patents

Description

The technology disclosed in this specification relates to a method for manufacturing an electrode sheet for a battery.

Patent Document 1 describes a method for manufacturing an electrode sheet. In this method, the metal sheet coated with the active material paste is transported through a drying furnace maintained at a high temperature, thereby drying the active material paste on the metal sheet.

JP 2019-29256 A

To dry the active material paste in a short time, it is necessary to increase the temperature inside the drying oven. However, the temperature inside the drying oven tends to be uneven, making it difficult to properly manage the temperature inside the drying oven. As a result, there is a risk that the manufacturing quality of the electrode sheet will decrease due to unintended thermal deformation of the metal sheet. This specification provides a technology that can avoid such problems and improve the manufacturing quality of the electrode sheet.

The technology disclosed in this specification is embodied in a method for manufacturing an electrode sheet. This manufacturing method includes a coating step of coating an active material paste onto the 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.

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 easier 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 strike 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 the water vapor generated by drying.

1 shows a schematic configuration of an electrode sheet manufacturing apparatus 10 used in the examples. FIG. 2 is a side view showing the configuration of a drying device 16. 2 is a diagram showing an irradiation area 20a and a non-irradiation area 20b of laser light L in a plan view. FIG.

In one embodiment of the present technology, the at least one light source may include multiple light sources arranged along the transport direction of the metal sheet. That is, the number of light sources is not limited to one, and multiple light sources may be used depending on, for example, the target drying time. Furthermore, by using multiple 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.

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). This allows the temperature of the active material paste to be appropriately controlled, and the active material paste to be dried uniformly in a short time.

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 inside the drying oven reaches a predetermined target temperature. In this case, the predetermined target temperature is not limited to a specific temperature, but may be a temperature range with a certain width.

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 water vapor 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 may be affected by the temperature, and the manufacturing quality of the electrode sheet may decrease.

The 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.

As shown in FIG. 1, the 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.

The coating device 14 is a device that applies 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.).

The drying device 16 is a device that applies the active material paste 4. The drying device 16 is also arranged on the transport path of the metal sheet 2 by the transport device 12. The drying device 16 is located downstream of the coating device 14 in the transport direction X of the metal sheet 2, and quickly dries the active material paste 4 applied to the surface of the metal sheet 2.

As shown in FIG. 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 through the drying furnace 18. The specific configuration of the drying furnace 18 is not particularly limited, but it is preferable for the drying furnace 18 to have thermal insulation properties in order to maintain the internal temperature.

The multiple light sources 20 irradiate the metal sheet 2 transported through the drying furnace 18 with laser light L. 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 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.

2 and 3, a certain interval is provided between the multiple irradiation areas 20a. As a result, a non-irradiation area 20b where 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 excessive temperature rise of the metal sheet 2. Note that the position and dimensions of the irradiation area 20a in the width direction of the metal sheet 2 match the position and dimensions of the active material paste 4 applied to the metal sheet 2.

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. The hot air B outlet 22a 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 should be 80°C or higher and 150°C or lower, and the temperature of the hot air B should be a temperature corresponding thereto.

The drying oven 18 is provided with an oven temperature sensor 26 and multiple sheet temperature sensors 24. The oven temperature sensor 26 can measure the temperature inside the drying oven 18. This allows the temperature or volume of the hot air B supplied into the drying oven 18 to be adjusted 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 mentioned above). This adjustment may be performed by an operator or automatically by a control device. Although not limited to this, the oven temperature sensor 26 is provided near the air outlet 22a.

The sheet temperature sensor 24 measures the temperature of the metal sheet 2. Although not limited to this, the sheet temperature sensor 24 is a non-contact type temperature sensor that measures the temperature of the metal sheet 2 from its back surface. The multiple sheet temperature sensors 24 are provided for each of the multiple 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 sheet temperature sensors 24 is not limited to this. The drying device 16 only needs to be equipped with at least one sheet temperature sensor 24 regardless of the number of light sources 20. The sheet temperature sensor 24 may also be one that measures the temperature of the metal sheet 2 from its surface, i.e., one that measures the temperature of the active material paste 4 on the metal sheet 2.

In the electrode sheet manufacturing method using the manufacturing apparatus 10, a coating process is carried out in which the 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 process, a drying process is carried out in which the active material paste 4 on the metal sheet 2 is dried. The drying process is carried out in a drying oven 18. In the drying oven 18, hot air is blown along the transport direction X of the metal sheet 2, and laser light L is irradiated from multiple light sources 20 to the active material paste 4 on the metal sheet 2. By irradiating the laser light L, the temperature of the active material paste 4 becomes higher than the temperature in the drying oven 18.

In the above-mentioned manufacturing method, the supply of hot air B into the drying furnace 18 and the irradiation of laser light L onto the active material paste 4 are combined, so that 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 the active material paste 4 can 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 hit 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 the water vapor generated by drying without causing unnecessary effects (e.g., local temperature changes) on the active material paste 4.

2: Metal sheet, 4: Active material paste, 10: Manufacturing device, 12: Conveyor device, 14: Coating device, 16: Drying device, 18: Drying furnace, 20: Light source, 20a: Irradiation area, 20b: Non-irradiation area, 22: Furnace temperature sensor, 24: Sheet temperature sensor, L: Laser light, B: Hot air

Claims (3)

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