JP2003117468A - Electrode coating device - Google Patents

Abstract

(57) [Summary] [Problem] It is easy to change application conditions, and shows excellent film thickness uniformity and reproducibility even when a small amount of paint is applied. SOLUTION: A worktable 11 on which a coating base material is installed and whose surface is a mirror surface faces a coating base material on the worktable 11 at a predetermined distance, and a coating material having a predetermined thickness is coated on the coating base material. It has a coating blade 16 for coating, and an equalizing means 23 for maintaining a constant distance between the surface of the coating substrate and the coating blade 16 according to the surface shape of the worktable 11 or the coating substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode coating device for coating a coating material on a coating substrate.

[0002]

2. Description of the Related Art Many portable electronic devices such as VTRs with built-in cameras, mobile phones, laptop computers, etc. have appeared.
Its size and weight are being reduced. There is an increasing demand for smaller and lighter batteries, particularly secondary batteries, which serve as power supplies for these electronic devices.

Furthermore, in recent years, along with the diversification of the usage environment and usage methods of electronic devices, it is required for the batteries to be mounted to comply with all usage environments and usage methods. For example, it is also envisioned that the battery has a curved surface shape that fits a part of the human body and is used in direct contact with the human body, such as a battery stored in a part of clothes and used.

However, since the conventional battery uses a liquid or gel electrolyte, the electrolyte may leak from the container of the battery, which is not suitable for the above-mentioned application to the human body.

Therefore, a so-called solid electrolyte battery using a solid electrolyte containing no liquid electrolyte has been devised.
A solid electrolyte battery is generally a positive electrode current collector made of a metal aluminum foil or the like, a positive electrode mixture layer containing a positive electrode active material, a solid electrolyte layer having lithium ion conductivity and no electron conductivity. A negative electrode active material layer made of metallic lithium or the like,
A negative electrode current collector made of metal copper foil or the like is laminated in this order.

Since the solid electrolyte battery does not contain a solvent as the electrolyte, it does not generate a gas even when heated, and has no inconvenience that a liquid component leaks from the container and exhibits extremely high safety.

For this reason, the solid electrolyte battery does not require a rigid exterior material unlike the conventional liquid type battery, and a flexible film-like exterior material can be used. Since the solid electrolyte battery does not require a rigid exterior material, the degree of freedom of the shape is remarkably increased as compared with a liquid battery, and it is possible to realize a usage method in which flexibility is required, for example.

In order to put into practical use a solid electrolyte battery satisfying such new requirements, there are various aspects such as battery material development, functional product form development, new production process development, product technology development, etc. R & D is required.

[0009]

By the way, the above-mentioned positive electrode mixture layer and solid electrolyte layer of the solid electrolyte battery are formed by applying a coating material onto the positive electrode current collector.

[0010] In the development of product form and production process, it is necessary to produce and verify electrodes and electrolytes in a form close to the actual product even at the research and development stage. Therefore, a technique for forming the positive electrode mixture layer and the solid electrolyte layer with high accuracy and reproducibility while changing various materials and conditions is required.

In other words, in order to develop a new material or process, the setting on the coating apparatus side, that is, the setting of the coating condition is managed while clearly distinguishing between the changing condition and the non-changing condition. It is necessary to apply by wiping. Further, in order to improve the reliability of the evaluation data, it is necessary to repeat the coating process under the set conditions a number of times to obtain the evaluation data. Therefore, the electrode coating device is required to have high precision reproducibility. .

However, at present, there is no electrode coating apparatus which realizes a coating technique capable of changing various conditions while maintaining accurate coating precision even in a small amount of production.

For example, in the method using a roll coater,
Although it is possible to apply a uniform film thickness, it is impossible to apply a small amount of paint required at the trial production stage. Further, the method using screen printing is suitable for applying a small amount of paint, but it is difficult to ensure the film thickness uniformity, and there is a disadvantage that a variation of about ± 10% with respect to the desired film thickness occurs. is there. Further, conventionally known coating methods for coating materials such as spin coating, film transfer, spray coating, and dip coating also have some disadvantages.

Therefore, the present invention has been proposed in view of such conventional circumstances, and it is easy to change the coating conditions, and even if a small amount of paint is applied, excellent film thickness uniformity and reproducibility are obtained. It is an object of the present invention to provide an electrode coating device showing.

[0015]

In order to achieve the above-mentioned object, an electrode coating apparatus according to the present invention is provided with a coating base, a workbench having a mirror surface, and a coating on the workbench. Maintains a constant distance between the coating blade and the coating blade that faces the substrate with a predetermined distance and coats the coating material on the coating substrate, and the workbench or the surface shape of the coating substrate. And equalizing means for performing the same.

In the electrode coating apparatus configured as described above, the coating base material is placed on the workbench, and then a predetermined gap is formed between the coating blade and the coating base material. Then, while supplying a desired amount of coating material on the coating base material, while moving the coating blade in the coating direction at a constant speed, while maintaining a constant gap by the equalizing means,
The coating material is applied on the application base material.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an electrode coating apparatus to which the present invention is applied will be described in detail with reference to the drawings.
This electrode coating device is applied to manufacture electrodes used in batteries such as solid electrolyte batteries. That is, the electrode coating device coats the current collector, which is the coating substrate, with the coating material to form the mixture layer.

As the current collector, an aluminum foil or the like can be used when manufacturing a positive electrode, and a copper foil or the like can be used when manufacturing a negative electrode.

As the coating material for forming the mixture layer, a coating material prepared by dispersing a positive electrode active material such as LiCoO ₂ in a solvent is used when manufacturing a positive electrode. Further, when a negative electrode is produced, a coating material obtained by dispersing a negative electrode active material or the like in a solvent is used. The term “mixture layer” as used herein refers to a layer containing an active material and also includes a case containing a binder, a solid electrolyte or the like.

As shown in FIG. 1, the electrode coating device 1 comprises:
The device main body 2 for applying the coating material on the current collector, the fixed clamp 3 and the movable clamp 4 which are located on both sides of the device main body 2 and set the application base material on the device main body 2, and the movable clamp 4. A tensioner 5 for transmitting power to apply tension to the coating substrate, an operation unit 6 for operating the apparatus main body 2 and the like, and a control unit 7 for controlling all operations of the electrode coating apparatus 1 are provided. ing.

As shown in FIGS. 1 and 2, the apparatus main body 2 is installed on a floor, a desk or the like to support the entire load of the apparatus main body 2, and a base 8 attached to the lower surface of the base 8. A plurality of level adjusters 9 that absorb unevenness of a floor or a desk as a place, a pair of ribs 10 that are attached to the upper surface of the base 8 and are parallel to the coating direction, and a work table 11 that is horizontally supported by the pair of ribs 10. Equipped with. Further, the apparatus main body 2 includes a head unit drive system 12 installed on the lower surface of the workbench 11 and between the pair of ribs 10, and a head unit 13 movable in the coating direction.

The ribs 10 are provided between the base 8 and the workbench 11 to support the workbench 11. A space for accommodating the head unit drive system 12 is secured between the pair of ribs 10.

The workbench 11 has a base 8 via ribs 10.
It is fixed to. Since the surface of the workbench 11 is a surface on which the current collector is placed in close contact, the workbench 11 is a mirror surface on which no visible irregularities are seen. Specifically, the surface of the workbench 11 has an average roughness of 0.1 μm or less, and the waviness in the width direction is within ± 3 μm when the width of the workbench 11 is 30 cm, for example.

Since the workbench 11 has the above-mentioned smoothness and flatness, when the current collector is in close contact with the workbench 11, the surface of the current collector also maintains good smoothness and flatness. It As a result, a uniform mixture layer can be obtained without changing the gap in the width direction of the current collector.

On the other hand, when the surface of the workbench is not a mirror surface, the unevenness of the surface is transferred to the current collector, so that the gap is partially changed and the film thickness of the mixture layer is uniform. Is damaged. Further, foreign matter remains inside the surface irregularities, making it difficult to maintain a clean environment. For example, when a foreign substance having a size of several μm is mixed in a mixture layer having a film thickness of several μm to several tens of μm, even if the foreign substance is chemically stable, the interface between the produced electrode layer and each layer In this case, a local battery reaction imbalance may occur, causing an internal short circuit.

The portion of the workbench 11 that comes into contact with the current collector and / or the coating material is used for the battery material, organic solvent, acid, alkali, etc. used in the step of applying the electrode, the cleaning step after the application, etc. Sufficient hardness and chemical resistance are required to prevent physical and chemical changes.
It is preferable to use stainless steel such as 316 and SUS304, glass such as quartz glass, and resin material such as fluororesin. Further, the surface of the workbench 11 may be subjected to Ti coating, fluororesin processing or the like. On the other hand, if the workbench is poor in hardness and chemical resistance,
The physical or chemical change of the workbench also changes the coating characteristics and impairs reproducibility. Further, substances may be exchanged between the coating material and the workbench, and foreign matters such as ions and fine particles may be mixed in the coating film.

Further, it is preferable that the workbench 11 has a sufficient length and width so that electrodes of various shapes and sizes can be prototyped. For example, the workbench 11 has a flat plate shape having a width of 30 cm and a length of 100 cm.

By the way, the workbench 11 has a sufficient size as described above and, at the same time, is small enough to allow the electrode coating apparatus 1 to be installed at any place such as in a clean bench or on a laboratory table. Light weight is required. However, in order to secure this small size and light weight, the workbench 11
Due to the rigidity of the work table 11, the work table 11 is deformed and has a waviness of 10 μm or more in a portion of the work table 11 on which the coating base material is placed, for example, in a range of 100 mm or more.
In order to suppress the deformation of the workbench 11 within an allowable range of 10 μm or less, the size of the coating part, here, the coating surface used is limited to 100 mm or less, and the electrode coating device 1 is large. Although it is conceivable to increase the rigidity of the workbench 11 by increasing the weight and increasing the weight, these methods cannot satisfy both the above-described long-time coating and the downsizing and weight reduction of the electrode coating apparatus 1. is there.

Therefore, the electrode coating apparatus 1 to which the present invention is applied in order to allow the undulation in the longitudinal direction of the workbench 11 while achieving both compatibility with long-term coating and reduction in size and weight.
Has an equalize function. Details of the equalize function will be described later.

As shown in FIG. 3, on the surface of the workbench 11, a long current collector 14 fixed on the workbench 11 is provided.
The pair of spacers 15 may be installed so as to be parallel to each other so as to sandwich them from the width direction. This spacer 15
Has an arbitrary thickness, and defines the distance between the coating blade 16 and the current collector 14 (hereinafter referred to as a gap), that is, the thickness of the mixture layer. Spacer 15
For example, stainless steel and PET (polyethylene terepht)
halate) sheets are laminated in the thickness direction. By disposing the PET sheet on the surface on which the coating blade 16 slides, the lubricity between the coating blade 16 and the spacer 15 is ensured, and the coating blade 16 runs stably.

For example, as shown in FIG. 4, the thickness is 20 μm.
When the mixture layer 17 having a film thickness of 50 μm is formed on the current collector 14, the spacer 15 having a thickness of 70 μm, which is the sum of the current collector 14 and the mixture layer 17, is used. This spacer 15
Is, for example, 20 μm thick stainless steel and 50 μm thick
PET sheets are laminated. In addition, the spacer 15
It is preferable that the surface of (1) has smoothness within ± 1 μm.

When forming the mixture layer 17 on both sides of the current collector 14, as shown in FIG. 5, the mixture layer 17 is formed on one side.
The current collector 14 on which is formed is turned over and fixed on the workbench 11, and the coating material is applied. Spacer 1 used in this case
The thickness of 5 is set to be equal to the sum of twice the thickness of the target mixture layer 17 and the thickness of the current collector 14.

The spacer 15 may be installed not only directly on the surface of the workbench 11 but also on the current collector 14 as shown in FIG. In this case, the spacer 15
Is set to be equal to the thickness of the target mixture layer 17.
When forming the mixture layer 17 on both sides of the current collector 14, as shown in FIG. 7, the current collector 14 having the mixture layer 17 formed on one side is turned over and fixed on the workbench 11. At the same time, the spacer 15 is set on the current collector 14 in the region where the mixture layer 17 is formed, and the coating material is applied. The thickness of the spacer 15 used in this case is set to be equal to the thickness of the target mixture layer 17.

Although the spacer 15 may be used and used in any manner, the spacer 15 may be directly installed on the workbench 11 from the viewpoint of improving the uniformity of the thickness of the mixture layer 17. Is preferred.

The head unit 13 is connected to the head unit drive system 12 through the ribs 10 and has a cross-section gate-shaped frame structure surrounding the work table 11. Power from the head unit drive system 12 is transmitted to the head unit 13, and, for example, the workbench 1 having a length of 1000 mm.
It is possible to move in the horizontal direction within the range of 750 mm.

The head unit 13 has a pair of lifting springs 18 suspended from the upper surface of the head unit 13.
A vertical slider 19 suspended by a lifting spring 18, a load cylinder 20 for applying a vertical load to the vertical slider 19, and a pressure gauge 21 for monitoring the load applied to the load cylinder 20. A pair of linear guides 22 are attached to guide the vertical movement of the upper and lower sliders 19 and prevent the blurring in the longitudinal and width directions.

The upper and lower sliders 19 each have a bearing 23 substantially at the center in the width direction, and the coating blade 16 is exchangeably supported via the bearing 23.

The load cylinder 20 is composed of a fixed portion and a movable end. The fixed portion is fixed to the head unit 13 and the movable end is connected to the vertical slider 19.

The load cylinder 20 is preferably a cylinder such as a low-friction air cylinder which has a minimal sliding frictional force. As a result, the pressure set by the load cylinder 20 and the load actually applied to the coating blade 16 match, and the coating characteristics and reproducibility are improved.

When the application of the paint is started, air is supplied to the load cylinder 20 to lower the movable end and lower the vertical slider 19. That is, the load cylinder 20 transmits a downward force to the coating blade 16 via the vertical slider 19 and the bearing 23. At this time, while monitoring the pressure gauge 21, the air pressure of the load cylinder 20 is adjusted using a pneumatic precision regulator.

The pull-up spring 18 has one end fixed to the head unit 13 and the other end having a vertical slider 19.
It is fixed to. As a result, the lifting spring 18
Vertical slider 19, bearing 23 and coating blade 1
A force in the direction of canceling the weight of 6, that is, an upward force is generated. The tension of the pull-up spring 18 is set so that the pressure when the coating blade 16 spreads the paint on the current collector when the load of the load cylinder 20 is zero, that is, the printing pressure is almost zero. As a result, the load calculated from the air pressure monitored by the pressure gauge 21 and the bore diameter of the load cylinder 20 and the force actually applied to the coating blade 16 match, and the reproducibility of the coating pressure is improved. Planned.

The pressure gauge 21 includes a load cylinder 20 when the load cylinder 20 applies a downward force to the upper and lower sliders 19.
Displays the air pressure supplied to. The set value of the pressure of the coating blade 16 generated by the load cylinder 20 is the pressure gauge 21.
It is possible to monitor by the air pressure displayed on the screen, and the reproducibility of the coating pressure can be improved by monitoring this air pressure.

The upper and lower sliders 19 include a movable portion contacting the linear guide 22, a load cylinder 20, and a pull-up spring 18.
And a housing to which the bearing 23 is fixed. The vertical slider 19 is guided by the linear guide 22 to move in the vertical direction, and prevents blurring in the longitudinal direction and the width direction. Vertical slider 19
Is subjected to a downward force by the load cylinder 20, the weight of the upper and lower sliders 19, the bearing 23, and the coating blade 16. In addition, the upper and lower sliders 19 have a pull-up spring 18
Receives an upward force.

The bearing 23 connects the upper and lower sliders 19 and the coating blade 16 and gives them a uniaxial rotational freedom, and has a so-called equalizing function.

FIG. 8A shows the equalizing function.
As shown in FIG. 5, a case where the application is performed using the work table 11 having a waviness in the longitudinal direction will be described as an example. Note that, in FIG. 8, only the work table 11, the coating blade 16, and the spacer 15 are illustrated and the other members are omitted for simplification of description. Further, in FIG. 8, the bearing 23 is schematically shown.

The operation of the blade 20 at points b and c of the workbench 11 shown in FIG. 8 (a) is shown in FIGS. 8 (b) and 8 (c), respectively.

As shown in FIGS. 8 (b) and 8 (c),
The coating blade 16 slightly swings around the bearing 23 as an axis (fulcrum) according to the inclination of the work table 11 in the width direction so that its tip is always parallel to the surface of the work table 11, and the gap is constant. To maintain. That is, even when the workbench 11 has a waviness in the longitudinal direction, the coating blade 16 travels in a state of following the surface shape of the workbench 11 to allow this waviness, and to provide a highly accurate and uniform film thickness. To form a mixture layer.

The equalizing function exerts a similar effect not only when the workbench 11 has undulations in the longitudinal direction as described above, but also when the current collector 14 has undulations in the longitudinal direction.

At least the portion of the coating blade 16 to which the coating material adheres at the time of coating is the apparatus main body 2 such as the bearing 23.
It is said that it can be separated from and replaced. Coating blade 16
By changing the coating blade 16, the installation angle of the coating blade 16, the material of the coating blade 16, the tip shape of the coating blade 16, the distance from the workbench 11, the coating condition such as the coating material supply method, and the coating blade 16 alone. Cleaning the
Maintenance such as accuracy confirmation of the coating blade 16 becomes easy.

In order to obtain a mixture layer having a uniform film thickness, the tip of the coating blade 16 which comes into contact with the coating material is required to have substantially the same planarity and smoothness as the workbench 11. Specifically, the tip of the coating blade 16 is preferably a mirror surface, and more specifically, the tip of the coating blade 16 has an average roughness of 0.1 μm or less. The waviness in the width direction when the width is 30 cm is within ± 3 μm. The radius of curvature of the tip of the coating blade 16 is preferably 1 mm to 10 mm, more preferably about 3 mm.

On the other hand, if the tip of the coating blade 16 is uneven, the gap is partially changed and the uniformity of the mixture layer is impaired. Further, if unevenness is present at the tip of the coating blade 16, foreign matter tends to remain, which hinders maintenance of a clean environment.

Further, the tip of the coating blade 16 is sufficient so as not to physically or chemically change with respect to a battery material, an organic solvent, an acid, an alkali, etc. used in a step of coating an electrode, a cleaning step after coating and the like. Since various hardness and chemical resistance are required, it is preferable to use stainless steel such as SUS316 and SUS304, glass such as quartz glass, and resin material such as fluororesin. Further, the tip of the coating blade 16 may be subjected to Ti coating, fluororesin processing or the like. On the other hand, when the workbench is poor in hardness and chemical resistance, the workbench is physically or chemically changed to change the coating characteristics and impair the reproducibility. Further, substances may be exchanged between the coating material and the workbench, and foreign matter ions, fine particles, and the like may be mixed in the mixture layer.

The head unit drive system 12 is composed of a servo motor, a transmission, a ball screw, and a power transmission pulley, and moves the head unit 13 horizontally with respect to the work table 11 at a constant speed. The head unit drive system 12 can drive the head unit 13 with accurate reproducibility without varying the moving speed, position, and stroke of the head unit 13 for each application.

Further, it is preferable that the head unit drive system 12 has a height lower than that of the workbench 11 and is installed at a position which does not directly face the surfaces of the coating blade 16 and the workbench 11. As a result, the linear guide 22
It is possible to prevent the minute scattered matter generated from the head unit drive system 12 from adhering to the current collector, the workbench 11 and the coating blade 16 which require strict smoothness. At the same time, even if the paint is scattered, the paint is prevented from adhering to the traveling system such as the linear guide and the head unit drive system 12.

The fixed clamp 3 is arranged on the coating start side of the apparatus main body 2 and holds one end of a long current collector. Specifically, the fixed clamp 3 has substantially the same height as the workbench 11 and includes a rigid clamp receiver 3a and a clamp holder 3b whose clamp force can be adjusted by air pressure or the like, and the clamp holder 3b. By moving up and down, the current collector is clamped with a predetermined clamping force.

The movable clamp 4 is arranged on the coating end side of the apparatus main body 2 so as to be movable in the coating direction, and holds the other end of the elongated current collector. Specifically, the movable clamp 4 includes a clamp receiver 4a made of an elastic body,
The clamp retainer 4b is made of a rigid body, and the clamp retainer 4b moves up and down to clamp the current collector with a predetermined clamping force.

The tensioner 5 applies a force in the coating direction to the movable clamp 4 by using an air cylinder or the like. The tensioner 5 acts substantially on the center of the movable clamp 4 in the width direction to give a tension to the current collector, and even when the direction of the current collector has an angle with the coating direction, the tension on the current collector is uniform. It has a uniaxial rotation degree of freedom.

The operation unit 6 is a drive unit of the electrode coating apparatus 1,
That is, the head unit drive system 12, the load cylinder 2
0, fixed clamp 3, movable clamp 4, tensioner 5 and the like have an operation panel for operating basic operations. Operation part 6
Make sure that the dust generated when operating the
The operation unit 6 is preferably arranged at a position lower than and separated from the work table 11 and the coating blade 16.

The control unit 7 controls the drive unit of the electrode coating apparatus 1, that is, the head unit drive system 12, the load cylinder 20, the fixed clamp 3, the movable clamp 4, the tensioner 5, and all other operations such as air and electricity. It contains functions. The control unit 7 is disposed at a position lower than and separated from the workbench 11 and the coating blade 16 so that dust generated from the air system or the cooling fan of the control unit 7 does not affect the current collector. Preferably. Operation part 6
The control unit 7 and the control unit 7 are connected by a cable.

Next, a method for producing an electrode by applying a coating material on the current collector by using the electrode coating apparatus 1 having the above-described structure will be described.

When the coating material is applied on the current collector, the electrode coating apparatus 1 is installed in a dry environment such as a dry room or a dry chamber. Since the battery material contains elements having high reactivity with water such as alkaline earth metals such as Li and Na and halogen such as F and Cl, it functions as a battery material by reacting with water in the air. This is because there is a risk that they will not do so. Also, to prevent foreign matter from entering the electrodes,
The place where the electrode coating device 1 is installed is in a clean state.

First, the fixed clamp 3 and the movable clamp 4
Also, the current collector is fixed to the surface of the work table 11 using the tensioner 5.

First, a current collector is placed on the surface of the workbench 11 approximately at the center in the width direction while utilizing positioning marks, guides and the like. As the current collector, for example, a foil made of aluminum foil, having a width of 140 mm, a thickness of 20 μm, and a tensile strength of about 30 kgf can be used, but the current collector is not limited to this.

Next, as shown in FIG. 9, one end of the current collector 14 extending from the workbench 11 is clamped and fixed by the clamp receiver 3a and the clamp retainer 3b of the fixed clamp 3.

Next, the current collector 14 placed on the surface of the workbench 11 is leveled on the surface of the workbench 11 to remove the floating of the current collector 14.

Next, as shown in FIG. 10, the other end of the current collector 14 extending from the workbench 11 is clamped and fixed by the clamp receiver 4a and the clamp retainer 4b of the movable clamp 4.

Further, as shown in FIG. 11, the clamp retainer 4b of the movable clamp 4 is lowered to deform the clamp receiver 4a made of an elastic body. Along with the deformation of the clamp receiver 4a, the current collector 14 is bent according to the shape of the chamfered corner of the work table 11, and a certain amount of tension is applied to the current collector 14.

Next, the fixed clamp 3 and the movable clamp 4
While holding the current collector 14 from both sides, the tensioner 5
Air is supplied to the movable clamp 4 and the movable clamp 4 is pulled in the coating direction, that is, in the direction of arrow A in FIG. At this time, the tension applied to the current collector 14 is preferably about 1 kgf. As described above, as shown in FIG. 12, the current collector 14 is fixed in close contact with the surface of the workbench 11.

Next, a paint is applied on the current collector 14.
Here, the application means forming the coating material in the form of a film on the current collector 14.

First, a pair of spacers 15 are installed on the surface of, for example, the workbench 11 so as to be parallel to each other with the long current collector 14 fixed on the workbench 11 sandwiched from the width direction.

Next, by supplying air to the load cylinder 20, the vertical slider 19 is lowered to a predetermined position, and a predetermined coating pressure is applied to the coating blade 16 via the bearing 23. The coating pressure applied to the coating blade 16 can be set arbitrarily, but is, for example, 0.3 kgf to 5 kg.
It is preferably about kgf.

Next, a required amount of paint is supplied onto the collector 14 on the coating direction side of the coating blade 16.

Next, the head unit drive system 12 is driven to transmit power to the head unit 13, and the head unit 13 is moved at a constant speed in the arrow B direction in FIG. The coating speed at this time is, for example, 100 mm / sec to 200 m.
It is preferably about m / sec. Head unit 13
The coating blade 16 spreads the coating material on the current collector 14 as it moves in the horizontal direction, and the coating material that has passed through the gap becomes a mixture layer having a uniform film thickness. At this time,
Even when the workbench 11 and / or the spacer 15 has a waviness in the longitudinal direction, the gap is always kept constant by the equalizing function of the bearing 23, and the mixture layer 17 having a uniform film thickness is formed.

If necessary, the current collector 14 is fixed on the workbench 11 with the side on which the mixture layer 17 is formed facing down.
It is possible to apply the coating material to the opposite side of the current collector 14 in the same manner. That is, the electrode coating apparatus 1 to which the present invention is applied can manufacture an electrode in which the mixture layer 17 is formed on both surfaces of the current collector 14.

As described above, the electrode is completed in which the mixture layer 17 which is a coating film is formed on the current collector 14 which is a coating base material.

In the electrode coating apparatus 1 as described above, since the surface of the workbench 11 is a mirror surface, the uneven shape of the surface of the workbench 11 is not transferred to the current collector 14. Also,
The equalizing function of the bearing 23 allows the coating blade 16 to follow the current collector 14 at a constant interval even when the workbench 11 has a waviness in the longitudinal direction. Due to these synergistic effects, the coating blade 16 runs while maintaining a constant gap, and a mixture layer 17 having extremely high uniformity in film thickness in the width direction and the longitudinal direction can be obtained even when the amount of paint is small. . For example, when the materials and the coating conditions are unified and the coating is performed using the electrode coating apparatus 1, the coating film weight per unit area of the mixture layer 17 can be reproduced almost accurately.

Therefore, by using the electrode coating apparatus 1 to which the present invention is applied, it becomes easy to fabricate electrodes while changing various shapes and characteristics, and the reliability of evaluation data in trial production of electrodes is improved. Is greatly improved. That is, according to the present invention, it is possible to contribute to the development of research and development of batteries, such as the development of battery materials and production processes for high-mix low-volume production.

The electrode coating apparatus 1 to which the present invention is applied
Even when a high-viscosity coating material of about 5000 cps to 10000 cps is used, it is possible to apply a coating with excellent film thickness uniformity to a shape that is difficult to apply with a conventional coating device. Further, this electrode coating device realizes excellent film thickness reproducibility even when the coating is repeatedly performed with a small amount of paint.

Further, since the surface of the workbench 11 is a mirror surface, the foreign matter is prevented from remaining and the foreign matter such as a solid or a liquid having a size larger than the wavelength of light can be optically recognized. It is effective for maintenance and management of a clean environment in which the coating device 1 for use is used. As a result, the rate of occurrence of battery defects such as internal short circuits is significantly reduced, and the reliability of evaluation data can be further improved.

Further, an electrode coating apparatus 1 to which the present invention is applied
When the workbench 11 is made of a material having excellent chemical resistance, the current collector 14 on which the mixture layer 17 is formed is turned upside down, that is, the surface of the workbench 11 is in contact with the mixture layer 17. Can be used even when used in. That is, the electrode coating apparatus 1 can relatively reduce the ratio of the current collector by forming the mixture layer 17 on both surfaces of the current collector 14, and can manufacture an electrode having a high charge / discharge density.

The electrode coating apparatus 1 to which the present invention is applied
Is preferably used for manufacturing an electrode of a solid electrolyte battery having a structure in which a liquid-type component such as a low-molecular solvent is not included as an electrolyte and a separator is not sandwiched between a negative electrode and a positive electrode. In the solid electrolyte battery having such a configuration, since the solid electrolyte layer has a function of preventing physical contact between the negative electrode and the positive electrode,
This is because the film thickness uniformity of the electrode is more severely required than that of the electrode of the battery using the separator.

Further, the electrode coating apparatus 1 to which the present invention is applied
Can be used for the production of both the negative electrode and the positive electrode, but is particularly preferably used for the production of the positive electrode. This is because the film thickness of the positive electrode at the time of coating, that is, the density of the positive electrode is related to the charge / discharge capacity and charge / discharge speed per unit area, and thus strict film thickness control is required.

[0083]

EXAMPLES Specific examples to which the present invention is applied will be described below based on experimental results.

Example As shown in FIG. 1, the coating material was applied to both main surfaces of the current collector by using an electrode coating device having a workbench having a mirror surface, a coating blade and a bearing. A mixture layer was formed and a positive electrode was actually manufactured.

At this time, the current collector as the coating base material has a tensile strength of about 30 kgf and a thickness of 20 μm.
And a long aluminum foil having a width of 140 mm was used. The viscosity of the paint used is 8 at 21.4 ° C.
It was 000 cps. The coating used was a positive electrode active material such as LiCoO ₂ , graphite, polyvinylidene fluoride and a polymer of ethylene oxide and 2- (2-methoxyethoxyethyl) glycidyl ether in N-methylpyrrolidone (NMP) as a solvent. It is one that is uniformly dissolved.

First, both ends of the current collector were held between a fixed clamp and a movable clamp, and the movable clamp was pulled by a tensioner. As a result, the current collector was brought into close contact with the surface of the workbench and a tension of about 1 kgf was applied to the current collector.

Also, on the workbench on both sides of the current collector in the width direction,
A pair of spacers were installed in parallel. This spacer is formed by laminating a PET sheet having a thickness of 50 μm on stainless steel having a thickness of 20 μm.

Next, air was supplied to the load cylinder, and the upper and lower sliders were lowered to the position where the tip of the coating blade formed a predetermined gap.

Next, 4.5 cc of the above-mentioned coating material was supplied to the current collector at approximately the center in the width direction and in the vicinity of the coating blade.

Next, the servo motor of the head unit drive system was driven to move the head unit in the direction of arrow B in FIG. 1 at a speed of 100 mm / sec. By passing the paint through the gap formed by the tip of the coating blade and the current collector, a coating film having a film thickness of 30 μm and a length of 54 mm was formed on one main surface of the current collector. This coating film was sufficiently dried to remove the solvent in the coating film to obtain a mixture layer.

The film thickness of the obtained mixture layer was measured as follows. As shown in FIG. 13, coating was performed on a center line C of the positive electrode, a line R parallel to the center line C at intervals of 30 mm in the width direction, and a line L symmetrical to the line R at the center line C. The film thickness of the mixture layer on each line was measured at 30 mm intervals from the starting point. A contact type film thickness meter was used to measure the film thickness.

Next, the above current collector was turned upside down and fixed to the workbench so that the coating film was in close contact with the workbench. And
A coating material was applied to the other main surface of the current collector in the same manner as described above to form a coating film having a film thickness of 30 μm. This coating film was sufficiently dried to remove the solvent in the coating film to obtain a mixture layer.

As described above, a positive electrode having a mixture layer formed on both surfaces of the current collector was obtained.

With respect to the obtained positive electrode, the thickness of the center line C, the line R, and the line L at intervals of 30 mm was measured in the same manner as the thickness measurement of the mixture layer on the one main surface side.

FIG. 14 shows the film thickness of one layer of the mixture layer measured as described above. In addition, the difference between the total thickness of the positive electrode and the thickness of the current collector, that is, the sum of the film thicknesses of the mixture layers on both surfaces is shown in FIG.
4 shows.

[0096] Comparative Example As a comparative example, without using the electrode coating apparatus as shown in FIG. 1, using a doctor blade manually, by applying a coating material on both main surfaces of the current collector case An agent layer was formed and a positive electrode was actually manufactured.

At this time, as the current collector, the same current collector used in the above-mentioned examples was used. The composition of the paint used was the same as that of the paint used in the above-mentioned examples, but the viscosity was 7800 cps at 24.8 ° C.

Then, in the same manner as in the above-mentioned embodiment, the film thickness of the mixture layer in the state where the coating material was applied to one surface of the current collector and the state in which the mixture layer was formed on both surfaces of the current collector were obtained. The film thickness was measured respectively.

FIG. 15 shows the film thickness of one layer of the mixture layer measured as described above. In addition, the difference between the total thickness of the positive electrode and the thickness of the current collector, that is, the sum of the film thicknesses of the mixture layers on both surfaces is shown in FIG.
5 shows.

From FIG. 14, it can be seen that in the embodiment, by using the electrode coating apparatus as shown in FIG. 1, a mixture layer having a stable film thickness can be obtained regardless of the coating position.
On the other hand, in the comparative example, it can be seen from FIG. 15 that it is difficult to control the film thickness because the film thickness varies greatly depending on the coating position.

FIG. 16 shows a graph in which the film thickness uniformity of the mixture layer after coating on one side and the mixture layer after coating on both sides in Examples and Comparative Examples was calculated and compared. Thickness uniformity (%)
Is calculated according to the following formula from film thickness values of 30 or more points. Thickness uniformity (±)% = (3 x standard deviation)
/ (2 × average value) From FIG. 16, it can be seen that in the comparative example in which the coating is manually applied, the film thickness uniformity is about ± 20% on one side and about ± 15% on both sides. On the other hand, in the example using the electrode coating apparatus shown in FIG. 1, the film thickness uniformity was significantly improved as compared with the comparative example, and the good film thickness within ± 5% on both one surface and both surfaces. Uniformity was obtained. This ± 5%
The film thickness uniformity within is usually a value that can be realized only when a coating material of about 3000 cps or less is applied by spin coating or a slit coater.

[0102]

As is apparent from the above description, in the electrode coating apparatus according to the present invention, the workbench surface is a mirror surface and the gap between the coating blade and the coating substrate is equalized by the equalizing means. Since the thickness is constant, a coating film having a uniform film thickness is formed. Moreover, according to the electrode coating apparatus of the present invention, good reproducibility of the film thickness of the coating film can be realized even when a small amount of coating material is coated while changing various materials and coating conditions.

Therefore, according to the present invention, it is possible to manufacture an electrode with highly reliable evaluation data, and it is possible to provide an electrode coating apparatus suitable for use as a coating apparatus for trial production of electrodes.

[Brief description of drawings]

FIG. 1 is a perspective view of an electrode coating device to which the present invention is applied.

2 is a cross-sectional view of the electrode coating apparatus shown in FIG. 1 with a coating blade removed.

FIG. 3 is a perspective view showing a state in which a pair of spacers are installed on the surface of the workbench.

FIG. 4 is a cross-sectional view for explaining a state in which a spacer is installed on the surface of a workbench and a mixture layer is formed on one surface of a current collector.

FIG. 5 is a cross-sectional view for explaining a state in which a spacer is installed on the surface of a workbench and a mixture layer is formed on both surfaces of a current collector.

FIG. 6 is a cross-sectional view for explaining a state in which a spacer is installed on a current collector and a mixture layer is formed on one surface of the current collector.

FIG. 7 is a cross-sectional view for explaining a state in which a spacer is installed on a current collector and a mixture layer is formed on both surfaces of the current collector.

FIG. 8A is a perspective view of a workbench having a waviness in a longitudinal direction. (B) is a cross-sectional view showing a state in which the coating blade is equalized with respect to the work table at the point b in (a). (C) is a cross-sectional view showing a state in which the coating blade is equalized with respect to the work table at point c in (a).

FIG. 9 is a side view showing a state in which a fixed clamp holds an application base material.

FIG. 10 is a side view showing a state in which the movable clamp holds the coating base material.

FIG. 11 is a side view showing a state in which the movable clamp applies tension to the coating substrate.

FIG. 12 is a perspective view showing a state in which a fixed clamp and a movable clamp sandwich an applied base material placed on a workbench surface.

FIG. 13 is a perspective view for explaining a position where a film thickness of a mixture layer is measured.

FIG. 14 is a graph showing the film thickness measurement results of the example.

FIG. 15 is a graph showing the results of measuring the film thickness of a comparative example.

FIG. 16 is a graph showing the film thickness uniformity of Examples and Comparative Examples.

[Explanation of symbols]

1 electrode coating device, 2 device body, 3 fixed clamp, 4 movable clamp, 5 tensioner, 6 operation part,
7 control unit, 8 base, 9 level adjuster, 10 ribs, 11 workbench, 12 head unit drive system, 13 head unit, 14 current collector, 15
Spacer, 16 coating blade, 17 mixture layer, 18
Lifting spring, 19 vertical slider, 20 load cylinder, 21 pressure gauge, 22 linear guide, 23 bearing

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshinari Sasaki             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Kimio Abe             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Konobu Shibuya             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Hirokichi Koshiba             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Hidetoshi Murase             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Kiyomi Kiyomi             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F-term (reference) 4F042 AA02 AA06 BA25 DD02 DD07                       DD18 DD20

Claims (10)

[Claims] 1. A workbench on which a coating base material is installed, the surface of which is a mirror surface, and a coating blade which faces the coating base material on the worktable at a predetermined distance and applies a coating material onto the coating base material. An electrode coating device comprising: an equalizing means for maintaining a constant distance between the surface of the coating base and the coating blade according to the work table or the surface shape of the coating base. 2. The electrode coating apparatus according to claim 1, further comprising a vertical slider that supports the coating blade so as to be vertically movable. 3. The electrode coating apparatus according to claim 2, wherein the equalizing means is a bearing provided on the upper and lower sliders. 4. The electrode coating apparatus according to claim 3, further comprising a head unit that supports the coating blade, the bearing, and the upper and lower sliders and is movable in a horizontal direction. 5. The electrode coating apparatus according to claim 4, further comprising drive means for driving the head unit at a constant speed. 6. The workbench has a center line average roughness of 0.1.
2. The electrode coating apparatus according to claim 1, wherein the width is less than .mu.m and the waviness in the width direction is within. +-. 3 .mu.m. 7. The electrode coating apparatus according to claim 1, wherein spacers are provided on both sides of the work table in the width direction to define a distance between the surface of the coating substrate and the tip of the coating blade. . 8. The electrode coating apparatus according to claim 1, wherein the coating blade is removable from the bearing. 9. The electrode coating apparatus according to claim 1, wherein the driving means is installed on a lower surface of the workbench. 10. The electrode coating apparatus according to claim 1, further comprising tensioning devices at both ends of the work table in the coating direction, the tensioning apparatus sandwiching the coating substrate and applying a predetermined tension to the coating substrate. .