JP2023010013A - Heating apparatus for electrode sheet for all-solid-state battery - Google Patents

Abstract

To provide a heating apparatus for an electrode sheet for an all-solid-state battery, capable of performing temperature management, specifically capable of effectively suppressing overheating.SOLUTION: By equipping a heating apparatus for an electrode sheet for an all-solid-state battery with a mechanism that can move the heating surface of an infrared heater in a parallel direction with respect to the heated surface of the electrode sheet, the heating surface of the heater is moved, after the conveyance of the electrode sheet is stopped, in a parallel direction with respect to the heated surface of the electrode sheet so that the heater is retracted from the electrode sheet, and both of the radiation amount and radiation time of heat supplied from the heater to the electrode sheet can be effectively controlled.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a heating device for an electrode sheet for an all-solid-state battery.

In recent years, high-performance batteries have been widely used as power sources for mobile devices, automobiles, and the like. An example of such a high-performance battery is an all-solid-state battery having a structure in which a plurality of unit cells are stacked together.

A laminate that becomes a unit cell constituting an all-solid-state battery is an electrode sheet in which a material (electrode active material) capable of reversibly absorbing and desorbing lithium ions is held by a conductive member (electrode current collector). It has Such an electrode sheet is produced by applying a paste (electrode mixture) containing an electrode active material to a conductive member (electrode current collector) and drying it by heating, or after drying, pressurizing to densify it. It is produced by performing the step of

As for the drying apparatus, Patent Literature 1 describes an apparatus that uses a mid-infrared heater to dry a substrate coated with a thick film paste in a predetermined pattern. According to the apparatus described in Patent Document 1, it is said that the thick film paste can be dried evenly.

Patent Document 2 describes a web drying apparatus comprising a plurality of hot air nozzles for blowing hot air and a plurality of electric far-infrared heaters. The device described in Patent Document 2 is said to be able to improve the drying performance by providing an electric heating type far-infrared heater capable of raising the surface temperature in a short time.

Further, Patent Document 3 describes an apparatus for drying an electrode sheet, in which a paste (electrode mixture) is applied to the surface of a conductive member (electrode current collector), with far infrared rays. According to the apparatus described in Patent Document 3, it is said that it is possible to efficiently and safely dry the electrode mixture by suppressing the shaking of the electrode sheet in the drying furnace without complicating the structure of the drying furnace. ing.

Furthermore, Patent Literature 4 describes an electrode manufacturing apparatus provided with an air blower that blows hot air in a direction parallel to the coating surface of an electrode current collector. According to the device described in Patent Document 4, by blowing hot air in a direction parallel to the coating film surface of the electrode current collector, rapid evaporation of the solvent from the coating film is suppressed, whereby the electrode mixture is It is said that the binder in the slurry coating film can be effectively prevented from migrating to the surface layer, and the binder distribution in the electrode can be made uniform.

Japanese Patent Application Laid-Open No. 2003-185338 JP-A-5-008372 JP-A-9-129221 JP 2014-086172 A

In manufacturing the electrode sheets that make up the unit cells of all-solid-state batteries, it is necessary to heat the paste (electrode mixture) applied to the surface of the conductive member (electrode current collector) under strict temperature control. There is

However, in the drying apparatuses described in Patent Documents 1 to 4, it is difficult to perform heating with strict temperature control. For example, in the case of the drying apparatus described in Patent Document 1, the electrode sheet coated with the paste (electrode mixture) is overheated when the temperature of the heater is increased before transportation or when the heater is cooled after transportation is stopped. There was a risk of causing

The present invention has been made in view of the above background, and provides an apparatus for heating an electrode sheet for an all-solid-state battery that enables temperature control and, in particular, can effectively suppress overheating. It is in.

In order to solve the above problems, the inventors have made detailed studies on the temperature of the electrode sheet. The inventors have focused on the fact that the temperature of the electrode sheet is determined by the radiant energy supplied from the heater to the electrode sheet (which is proportional to the surface temperature of the heater and proportional to the reciprocal of the conveying speed of the electrode sheet).

As for the surface temperature of the heater, as shown in FIG. 1, it was found that the temperature decreased slightly even after a certain amount of time had passed after the heater was stopped. Regarding the transport speed, when the electrode sheet stops transporting, the radiant energy to the electrode sheet becomes larger than that during transport, so the temperature of the electrode sheet is higher when transport is stopped than during transport. becomes.

Therefore, the inventors of the present invention moved the heating surface of the heater in a direction parallel to the surface to be heated of the electrode sheet to retract the heater from the electrode sheet after stopping the transportation of the electrode sheet. It is possible to effectively control both the radiation amount and the radiation time of the heat supplied to the electrode sheet, and as a result, it is thought that overheating of the electrode sheet can be suppressed, and the present invention has been completed. That is, the present invention is as follows.

<<Aspect 1>>
A heating device for an electrode sheet for an all-solid-state battery for heating an electrode sheet in which an electrode mixture is applied to the surface of an electrode current collector,
an infrared heater having a heating surface arranged so as to face the surface to be heated of the electrode sheet; and moving the infrared heater parallel to the surface to be heated so as to face the surface to be heated A heating device for an electrode sheet for an all-solid-state battery, having a parallel movement mechanism for moving between a heating space and a retraction space not facing the surface to be heated.
<<Aspect 2>>
When the temperature of the electrode sheet reaches a set upper limit value in the heating space, the infrared heater is retracted from the heating space to the retraction space by the parallel movement, and the infrared heater is cooled in the retraction space. A heating device for an electrode sheet for an all-solid-state battery according to aspect 1.
<<Aspect 3>>
The temperature of the infrared heater is raised in the evacuation space, and when the temperature of the infrared heater reaches a set lower limit, the infrared heater is moved from the evacuation space to the heating space by the parallel movement, and the heating space is The heating device for an all-solid-state battery electrode sheet according to aspect 1 or 2, wherein the electrode sheet is heated at.
<<Aspect 4>>
The apparatus for heating an electrode sheet for an all-solid-state battery according to any one of modes 1 to 3, wherein the electrode sheet is conveyed by a roll-to-roll method.

In the apparatus for heating an electrode sheet for an all-solid-state battery of the present invention, the heating surface of the infrared heater moves in a direction parallel to the surface to be heated of the electrode sheet. Cooling of the heater after the transport of the electrode sheet is stopped can be performed at the place where the electrode sheet is evacuated.

Therefore, it is possible to effectively control both the radiation amount and radiation time of heat supplied from the infrared heater to the electrode sheet, and to effectively suppress overheating of the electrode sheet. As a result, in the manufacturing process of the electrode sheet for the all-solid-state battery, the target temperature can be managed without lowering the transport speed of the electrode sheet, and the electrode sheet can be manufactured efficiently.

It is a figure which shows the relationship between the elapsed time after a heater stoppage, and surface temperature. 4 is a top view showing the action of the heating device of Example 1. FIG. 4 is a side view showing the action of the heating device of Example 1. FIG. FIG. 11 is a top view showing the operation of the heating device of Example 2; FIG. 11 is a side view showing the operation of the heating device of Example 2; FIG. 11 is a top view showing the action of the heating device of Example 3; FIG. 11 is a side view showing the action of the heating device of Example 3; 5 is a graph showing changes in temperature of electrode sheets by heating devices produced in Examples and Comparative Examples.

Embodiments of the present invention will be described in detail below. It should be noted that the present invention is not limited to the following embodiments, and can be implemented in various modifications.

<<Heating device for electrode sheet for all-solid-state battery>>
The apparatus for heating an electrode sheet for an all-solid-state battery according to the present invention is applicable to the production of electrodes constituting unit cells of an all-solid-state battery, and is a heating apparatus that enables heating under strict temperature control. be.

According to the heating device for the all-solid-state battery electrode sheet of the present invention, overheating of the electrode sheet can be effectively suppressed. It is possible to manage the target temperature without causing a temperature change, and to efficiently produce the electrode.

<<Configuration of Heating Device>>
<Infrared heater>
A heating device for an electrode sheet for an all-solid-state battery of the present invention includes an infrared heater. The infrared heater is for heating an electrode sheet in which an electrode mixture is applied to the surface of an electrode current collector, and a heating surface is arranged so as to face the surface to be heated of the electrode sheet.

The infrared heater provided in the heating device for the electrode sheet for an all-solid-state battery of the present invention is not particularly limited. It is preferable if it has a flat heating surface that can be arranged so as to face the surface to be heated of the electrode sheet.

Since the infrared heater is placed facing the heated surface of the electrode sheet, if the electrode mixture is applied to only one side of the electrode sheet, the infrared heater should face the surface coated with the electrode mixture. so that only one unit needs to be provided. When heating an electrode sheet coated with an electrode mixture on both sides, two infrared heaters in total, one on each side of the electrode sheet, may be provided so as to sandwich the electrode sheet. good.

<Parallel movement mechanism>
A heating device for an electrode sheet for an all-solid-state battery of the present invention includes a translation mechanism. The parallel movement mechanism moves the infrared heater parallel to the surface to be heated of the electrode sheet, and moves between the heating space facing the surface to be heated and the evacuation space not facing the surface to be heated. It is a mechanism that allows

The apparatus for heating an electrode sheet for an all-solid-state battery of the present invention uses a parallel movement mechanism to raise the temperature of the heater before starting the transportation of the electrode sheet and cool the heater after the transportation of the electrode sheet is stopped. can be done anywhere. As a result, it is possible to effectively control both the radiation amount and radiation time of the heat supplied from the infrared heater to the electrode sheet, and to effectively suppress overheating of the electrode sheet.

The configuration of the translation mechanism is not particularly limited. To move an infrared heater parallel to a surface to be heated of an electrode sheet so as to move in a direction parallel to the surface to be heated, to move to a space not facing the surface to be heated, and to return from the space not facing the surface to be heated to a space facing the surface to be heated. Any configuration that allows

For example, there is a mechanism in which a rotating shaft is arranged on the conveying line of the electrode sheet and the heater is rotated around the rotating shaft.

When the apparatus for heating an electrode sheet for an all-solid-state battery of the present invention is provided with two infrared heaters, the two infrared heaters are moved parallel to each other in the same side with respect to the conveying direction of the electrode sheet. It may be a mechanism or a mechanism for moving in parallel to different sides.

If it is desired to shorten the cooling time of the infrared heater, it is preferable to employ a mechanism for moving the infrared heaters in parallel to different sides.

<Other configurations>
(Temperature measuring means)
The apparatus for heating an electrode sheet for an all-solid-state battery of the present invention may include temperature measuring means for measuring the temperature of the heating surface of the infrared heater and the temperature of the heated surface of the electrode sheet. Based on the results obtained by the temperature measuring means, translational movement of the infrared heater is initiated.

(movement control means)
The apparatus for heating an electrode sheet for an all-solid-state battery of the present invention may include movement control means for controlling the parallel movement mechanism. The movement control means, for example, is means for determining whether or not the result obtained by the temperature measuring means has reached the set temperature, and transmitting a movement start command to the parallel movement mechanism based on the determination result. good.

<Electrode sheet for all-solid-state battery>
The all-solid-state battery electrode sheet to which the heating device of the present invention is applied is not particularly limited. It may be an electrode sheet for an all-solid-state battery with a known structure made of a known material.

An electrode sheet for an all-solid-state battery generally has a configuration in which an electrode mixture containing an electrode active material capable of reversibly intercalating and deintercalating lithium ions is held by an electrode current collector, which is a conductive member.

In its production, an electrode mixture paste containing an electrode active material is applied to the surface of the electrode current collector, and the electrode mixture paste is heated and dried under strict temperature control, or the electrode mixture is dried. After the paste is dried, it is pressurized and densified to form an electrode.

(electrode current collector)
Materials used for the electrode current collector include, for example, SUS, aluminum, copper, nickel, iron, titanium, carbon, and the like. Among them, the material of the positive electrode current collector layer is preferably aluminum, and the material of the negative electrode current collector layer is preferably copper.

Examples of the shape of the current collector layer include a foil shape, a plate shape, and a mesh shape. Among these, the foil shape is preferred.

(electrode mixture)
The electrode mixture contains an electrode active material. In addition, as optional components, a conductive aid, a binder, a solid electrolyte, and the like may be included.

Examples of the positive electrode active material used in the positive electrode mixture that serves as the positive electrode include lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), and LiCo _1/3 Ni ₁ . _/3 Mn _1/3 O ₂ , Li _1+x Mn _2-xy M _y O ₄ (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn). Li—Mn spinel substituted with a different element having a composition of
Not limited.

Examples of the negative electrode active material used in the negative electrode mixture that serves as the negative electrode include metal lithium and materials capable of intercalating and deintercalating metal ions such as lithium ions. Materials capable of intercalating and deintercalating metal ions such as lithium ions include, for example, alloy-based negative electrode active materials and carbon materials.

Examples of alloy-based negative electrode active materials include Si alloy-based negative electrode active materials and Sn alloy-based negative electrode active materials.

Si alloy-based negative electrode active materials include silicon, silicon oxides, silicon carbides, silicon nitrides, solid solutions thereof, and the like. In addition, the Si alloy-based negative electrode active material may contain elements other than silicon, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Sn, and Ti.

Sn alloy-based negative electrode active materials include tin, tin oxides, tin nitrides, and solid solutions thereof. The Sn alloy-based negative electrode active material may contain elements other than tin, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Ti, and Si.

Examples of carbon materials include hard carbon, soft carbon, and graphite.

Examples of conductive aids include VGCF (Vapor Grown Carbon Fiber), carbon materials such as carbon nanofibers, and metal materials.

Binders include, for example, materials such as polyvinylidene fluoride (PVdF), carboxymethyl cellulose (CMC), butadiene rubber (BR), styrene butadiene rubber (SBR), or combinations thereof.

(Conveyance method)
The electrode sheet applied to the heating device for the electrode sheet for an all-solid-state battery of the present invention may be conveyed by a roll-to-roll system.

Specifically, the electrode mixture paste is passed between adjacent rotating rolls and transferred onto the electrode current collector, thereby manufacturing and transporting the electrode mixture paste on the electrode current collector. can be anything.

When the electrode sheet is conveyed by the roll-to-roll method, working efficiency can be improved.

<<Action of the heating device>>
In the heating device for an electrode sheet for an all-solid-state battery of the present invention, when a preset temperature is reached, the infrared heater is moved parallel to the surface of the electrode sheet to be heated. It has an action of moving between a heating space facing the surface and a retreating space not facing the surface to be heated.

<Evacuate>
In the all-solid-state battery electrode sheet heating device of the present invention, when the temperature of the electrode sheet reaches the set upper limit value, the parallel movement mechanism performs parallel movement to retract the infrared heater from the heating space to the retraction space. and cool the infrared heater in the evacuation space.

Retraction of the heating device for the all-solid-state battery electrode sheet of the present invention will be described with reference to FIGS. 2 and 3. FIG.

2(a) and 2(b) are top views of a heating device for an electrode sheet for an all-solid-state battery according to one embodiment, and FIGS. 3(a) and 3(b) are front views of the device. It is a diagram. 2(a) and 3(a) show the state of the heating device in the heating space, and FIGS. 2(b) and 3(b) show the state of the heating device in the evacuation space.

The heating device for an electrode sheet for an all-solid-state battery according to one embodiment shown in FIGS. 2 and 3 includes two infrared heaters 1 and 3. , the electrode sheet 2 is placed and heated. In the electrode sheet 2 according to this embodiment, the electrode mixture is applied on both sides of the electrode current collector, and both sides of the electrode sheet are surfaces to be heated.

As shown in FIGS. 2A and 3A, in the heating space, the heating surfaces of the infrared heaters 1 and 3 are arranged so as to face the surface to be heated of the electrode sheet 2, and the electrode sheet 2 is heated.

Then, when the temperature of the electrode sheet reaches the preset upper limit of the set temperature, the infrared heater is retracted from the heating space to the evacuation space by parallel movement by the translation mechanism, and the infrared rays are emitted in the evacuation space. Cool the heater.

By retracting the infrared heater, it is possible to reduce both the radiation amount and radiation time of heat supplied from the infrared heater to the electrode sheet, and as a result, it is possible to suppress overheating of the electrode sheet.

As shown in FIGS. 2(b) and 3(b), the solid-state battery electrode sheet heating apparatus according to the present embodiment moves the two infrared heaters 1 and 3 in parallel in the same direction. to withdraw from the electrode sheet.

The solid-state battery electrode sheet heating apparatus of the present invention may stop conveying the electrode sheet when it is in the retracted state. An electrode can be obtained by pressurizing and densifying after stopping the transportation.

The set temperature that is set in advance for judging evacuation is not particularly limited. It can be appropriately set according to the composition, thickness, etc. of the electrode mixture within a range where overheating of the electrode sheet can be suppressed.

<Start of heating>
The heating device for an electrode sheet for an all-solid-state battery of the present invention raises the temperature of the infrared heater in the evacuation space, and when the temperature of the infrared heater reaches a set lower limit value, the parallel movement mechanism performs parallel movement to The heater is moved from the evacuation space to the heating space, and the electrode sheet is heated in the heating space.

The start of heating by the heating device for the electrode sheet for an all-solid-state battery of the present invention is parallel movement opposite to the retraction described above.

After heating the infrared heater in advance in the evacuation space, parallel movement is performed by the translation mechanism to move the infrared heater from the evacuation space to the heating space, and the electrode sheet is heated in the heating space.

Since the electrode sheet is not heated until the temperature of the infrared heater is sufficiently raised, both the radiation amount and radiation time of the heat supplied from the infrared heater to the electrode sheet can be reduced. Overheating of the sheet can be suppressed.

The set temperature that is set in advance to determine forward movement is not particularly limited. It can be appropriately set according to the composition, thickness, etc. of the electrode mixture within a range where overheating of the electrode sheet can be suppressed.

Hereinafter, the present invention will be described in more detail by showing experimental results. Example 1 and Comparative Examples 1 and 2 are examples in which the withdrawal mode of the infrared heater in the solid battery electrode sheet heating device is different.

<Production of electrode sheet>
A Ni foil was prepared as an electrode current collector. Also, as an electrode mixture, an electrode mixture paste containing nickel-cobalt-manganese oxide (NCM), which is a positive electrode active material, was prepared. An electrode sheet was produced by applying an electrode mixture paste to both sides of the Ni foil.

<Example 1>
2 and 3 show how the heating device for the electrode sheet for a solid battery used in Example 1 is retracted. The retraction mode of Example 1 is based on the heating apparatus of the present invention. Specifically, when the infrared heater is moved from the heating space to the retraction space, the infrared heater is moved in a direction parallel to the surface to be heated of the electrode sheet. It is translated in parallel so that it moves to

The retraction state in Example 1 is the same as that described in the above embodiment.

In the heating space, the heating surfaces of the infrared heaters 1 and 3 are arranged so as to face the surface to be heated of the electrode sheet 2 to heat the surface to be heated of the electrode sheet 2 . When the temperature of the electrode sheet reaches the preset upper limit of the set temperature, the infrared heater is moved to the evacuation space and cooled in the evacuation space.

In Example 1, the infrared heater is moved parallel to the surface of the electrode sheet to be heated, and retracted from the electrode sheet.

FIG. 8 shows changes in the temperature of the electrode sheet after the infrared heater is retracted. In FIG. 8, the horizontal axis indicates the elapsed time after the infrared heater is retracted, and the vertical axis indicates the temperature of the electrode sheet. Note that Max on the vertical axis is the preset upper limit of the set temperature.

<Comparative Example 1>
FIGS. 4 and 5 show how the solid-state battery electrode sheet heating device used in Comparative Example 1 is retracted. In the retraction mode of Comparative Example 1, when the infrared heater is moved from the heating space to the retraction space, it is moved in a direction perpendicular to the surface to be heated of the electrode sheet.

4(a) and 4(b) are top views of the heating device of Comparative Example 1, and FIGS. 5(a) and 5(b) are front views of the device. 4(a) and 5(a) show the state of the heating device in the heating space, and FIGS. 4(b) and 5(b) show the state of the heating device in the evacuation space.

The heating device for the all-solid-state battery electrode sheet of Comparative Example 1 shown in FIGS. As shown in 5(a), in the heating space, the electrode sheet 5 is placed between the infrared heaters 4 and 6 and heated.

When the temperature of the electrode sheet reaches the preset upper limit of the set temperature, the infrared heaters 4 and 6 are moved to the evacuation space, and the infrared heaters 4 and 6 are cooled in the evacuation space.

In Comparative Example 1, as shown in FIGS. 4(b) and 5(b), the two infrared heaters 4 and 6 were moved in a direction perpendicular to the surface to be heated of the electrode sheet, The electrode sheet 5 is retracted.

FIG. 8 shows changes in the temperature of the electrode sheet after the infrared heater is retracted, as in the first embodiment.

<Comparative Example 2>
FIGS. 6 and 7 show how the solid-state battery electrode sheet heating device used in Comparative Example 2 is retracted. The evacuation mode of Comparative Example 2 does not move the infrared heater from the heating space to the evacuation space, but inserts a stainless steel shielding plate between the heated surface of the electrode sheet and the heating surface of the infrared heater. It is.

6(a) and 6(b) are top views of the heating device of Comparative Example 2, and FIGS. 7(a) and 7(b) are front views of the device. 6(a) and 7(a) show the state of the heating device in the heating space, and FIGS. 6(b) and 7(b) show the state of the heating device in the evacuation space.

The heating device for the all-solid-state battery electrode sheet of Comparative Example 2 shown in FIGS. 6 and 7 includes two infrared heaters 7 and 10. Second, in the heating space, the electrode sheet 8 is placed between the infrared heaters 7 and 10 and heated.

Then, when the temperature of the electrode sheet reaches the preset upper limit of the set temperature, as shown in FIGS. 6(b) and 7(b), the two infrared heaters are Two shielding plates 9 are inserted between the heating surfaces of the infrared heaters 7 and 10 and the surface of the electrode sheet 8 to be heated.

FIG. 8 shows changes in the temperature of the electrode sheet after the shield plate 9 was inserted, as in the first embodiment.

<Discussion>
In Example 1, in which the infrared heater was retracted by moving parallel to the surface to be heated of the electrode sheet, the temperature of the electrode sheet was set to the upper limit of the set temperature (Max in FIG. 8). ), and it decreases significantly with the passage of time.

On the other hand, in Comparative Example 1, in which the infrared heater was retracted by moving in a direction perpendicular to the surface to be heated of the electrode sheet, the temperature of the electrode sheet increased for a while after retraction, and the preset setting The temperature exceeded the upper limit (Max in FIG. 8). That is, according to the heating device of Comparative Example 1, overheating could not be avoided.

In Comparative Example 2, in which two shielding plates were used to shield the heat from the infrared heater, the temperature of the electrode sheet did not exceed the preset upper limit of the set temperature (Max in FIG. 8). The decrease in temperature was moderate compared to Example 1.

1, 3, 4, 6, 7, 10 infrared heater 2, 5, 8 electrode sheet 9 shielding plate

Claims (4)

A heating device for an electrode sheet for an all-solid-state battery for heating an electrode sheet in which an electrode mixture is applied to the surface of an electrode current collector,
an infrared heater having a heating surface arranged so as to face the surface to be heated of the electrode sheet; and moving the infrared heater parallel to the surface to be heated so as to face the surface to be heated A heating device for an electrode sheet for an all-solid-state battery, having a parallel movement mechanism for moving between a heating space and a retraction space not facing the surface to be heated. When the temperature of the electrode sheet reaches a set upper limit value in the heating space, the infrared heater is retracted from the heating space to the retraction space by the parallel movement, and the infrared heater is cooled in the retraction space. The heating device for an electrode sheet for an all-solid-state battery according to claim 1. The temperature of the infrared heater is raised in the evacuation space, and when the temperature of the infrared heater reaches a set lower limit, the infrared heater is moved from the evacuation space to the heating space by the parallel movement, and the heating space is The heating device for an electrode sheet for an all-solid-state battery according to claim 1 or 2, wherein the electrode sheet is heated at. 4. The apparatus for heating an electrode sheet for an all-solid-state battery according to claim 1, wherein said electrode sheet is conveyed by a roll-to-roll method.

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