KR20110137734A - Coating apparatus and manufacturing method for electrode foil - Google Patents

Abstract

PURPOSE: A coating apparatus and a method for manufacturing an electrode foil are provided to improve the yield of an electrode and to reduce curvature on the cross section of a coated electrode. CONSTITUTION: A sheet shaped base material(20) is wound around a back-up roller(8). A die coater(10) applied electrode slurry(21) to the sheet shaped based material which is transferred on the back-up roller. The outer regions of the back-up roller support both width directional end parts of the wound sheet shaped base material. The center region of the back-up roller is arranged between the outer regions of the back-up roller. The outer diameters of the outer regions are more concaved than the outer diameter of the center region. The back-up roller is maintained at the low temperature which is lower than the temperature of the electrode slurry on the sheet-shaped base material by a cooling unit.

Description

Coating apparatus and manufacturing method of electrode foil {COATING APPARATUS AND MANUFACTURING METHOD FOR ELECTRODE FOIL}

This invention relates to the coating device used for manufacture of the electrode foil which comprises a secondary battery, and the manufacturing method of an electrode foil.

Conventionally, when manufacturing the electrode foil which comprises a secondary battery, the coating apparatus which apply | coats an electrode slurry (liquid containing an electrode active material) to a sheet-like base material (metal foil) WHEREIN: The thickness of the electrode layer apply | coated and constructed is shown by the edge part. The technique for including and making it uniform is proposed (refer patent document 1).

This is equipped with the coating apparatus provided with the backup roller by which the sheet-form base material was wound, and the die coater which apply | coats an electrode slurry to the sheet-form base material conveyed on the said backup roller image. And the peripheral surface of the site | part which an electrode slurry is apply | coated by the said die coater to a prescribed width on the wound sheet-like base material among the said backup rollers is formed in the circumferential surface, and the circumference | surroundings of the site | part which the applied electrode slurry flows and spreads to an edge part side similarly are carried out. The surface is formed so as to form a conical surface substantially coaxial with the circumferential surface and gradually shrinking in diameter toward the end portion of the backup roller.

Japanese Patent Application Publication No. 2008-173590

By the way, in order to thicken the electrode layer of electrode foil and to improve the capacity | capacitance of the secondary battery using it, it is necessary to make the viscosity of an electrode slurry high. Moreover, in order to raise productivity of an electrode foil, it is necessary to raise a coating speed.

However, when the above-mentioned high viscosity electrode slurry is discharged from the die coater head at a high speed, the flow rate of the electrode slurry discharged from the center of the die coater head is faster than the flow rate of the electrode slurry discharged from the end of the die coater head. As a result, the start shape and the end shape of the coated electrode become a curved shape, the end cannot be used as an electrode, requires cutting or the like, and the yield decreases.

Therefore, this invention is made | formed in view of the said problem, and an object of this invention is to provide the coating device and the manufacturing method of an electrode foil suitably in suppressing the curvature of the coating start start edge part of an electrode.

The present invention relates to a coating apparatus including at least a backup roller on which a sheet-like substrate is wound and a die coater for applying an electrode slurry to the sheet-like substrate conveyed on the backup roller. And the outer diameter of the outer area | region which supports the both ends of the width direction of the sheet-like base material wound up among the said backup rollers was made larger concave shape than the outer diameter of the center area | region sandwiched between the said outer area | regions.

Therefore, in the present invention, the sheet is discharged from the die coater head, and the sheet is held in the concave shape in the width direction center region by the backup roller in the shape of the tip portion of the electrode slurry in which the width direction center part becomes convex with respect to the width direction both ends. The shape of the shape base material can be similar. For this reason, the distance between the front-end | tip part of the electrode slurry taken out from a die coater head, and a sheet-like base material can be made equal at the center part and the edge part of a sheet-like base material, and the curvature of the edge part of the apply | coated coating can be reduced. Thus, the yield of the electrode is improved.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the manufacturing method of the electrode foil containing the coating device which shows one Embodiment of this invention.
2 is a front view showing a coating portion of the coating device.
3 is an explanatory diagram showing a coating state by a coating device;
4 is a front view showing a modification of the coating device.
5 is an explanatory diagram showing a coating state by a coating apparatus according to a modification.
6 is a front view illustrating another modification of the coating device.
7 is a perspective view (A) and a front view (B) of a backup roller of still another modification of the coating apparatus.
8 is an explanatory diagram showing a holding state of a seed-shaped substrate by a backup roller of another modification;

EMBODIMENT OF THE INVENTION Hereinafter, the manufacturing apparatus and the manufacturing method of an electrode foil which concern on one Embodiment of this invention are demonstrated based on drawing. The coating device 2 according to the first embodiment is used to manufacture an electrode foil used as an electrode of a secondary battery, and is an apparatus for forming the electrode layer 22 on the sheet-like substrate 20. . In manufacture of electrode foil, the electrode slurry 21 is apply | coated and dried to the sheet-like base material 20 by the said coating device 2, and the dried electrode layer 22 is a rolling apparatus which is not shown in figure which is a post process. It presses, it adjusts a density, it cuts out with electrode foil, and is used for a secondary battery.

The sheet-shaped base material 20 is a substrate for forming the electrode layer 22, and may be, for example, arbitrary depending on the kind and use of electrode foils manufactured such as aluminum foil, copper foil, nickel foil, iron foil, stainless steel foil, and the like. It is a metal foil. For example, metal foil, such as aluminum, can be used for a positive electrode collector, and metal foil, such as copper, can be used for a negative electrode collector. Although there is no restriction | limiting in particular about the specific thickness of metal foil, For example, it is a thin film of about 20 micrometers in case of aluminum, and about 10 micrometers in case of copper.

The electrode layer 22 is dried and pressed from a slurry-like fluid (electrode slurry 21) in which an electrode active material (positive electrode active material or negative electrode active material) dissolved in a solvent and a binder are mixed. There are a positive electrode slurry used for forming a positive electrode, and a negative electrode slurry used for forming a negative electrode. Hereinafter, when not specifically limited to any one of a positive electrode slurry and a negative electrode slurry, it is simply called "electrode slurry."

A positive electrode slurry has a positive electrode active material, a conductive support agent, and a binder, for example, and becomes a predetermined viscosity by adding a solvent. The positive electrode active material is lithium manganate, for example. The conductive aid is, for example, acetylene black. The binder is, for example, PVDF (polyvinylidene fluoride). The solvent is, for example, NMP (normal methylpyrrolidone). The positive electrode active material is not particularly limited to lithium manganate, but from the viewpoint of capacity and output characteristics, it is preferable to apply a lithium-transition metal composite oxide. For example, carbon black or graphite may be used for the conductive assistant. The binder and the solvent are not limited to PVDF and NMP.

A negative electrode slurry has a negative electrode active material, a conductive support agent, and a binder, for example, and becomes a predetermined viscosity by adding a solvent. The negative electrode active material is, for example, graphite. The conductive aid, the binder, and the solvent are, for example, acetylene black, PVDF, and NMP. In addition, a negative electrode active material is not specifically limited to graphite, It is also possible to use hard carbon and a lithium-transition metal composite oxide. For example, carbon black or graphite may be used for the conductive assistant. The binder and the solvent are not limited to PVDF and NMP.

As shown in FIG. 1, in the said coating device 2, the coating part 4 which has a function which apply | coats the electrode slurry 21 to the sheet-like base material 20, and the electrode slurry 21 are dried. The drying part 6 which has a function to make it is provided. The said drying part 6 consists of a drying furnace, for example, and passes through this drying part 6, and the solvent contained in the apply | coated electrode slurry 21 evaporates and it is forcibly dried. The drying furnace may be, for example, an induction heating drying furnace in which an induction coil applies a magnetic field to the metal foil to impart heat to the metal foil, and heats the electrode slurry 21 by the heat to evaporate the solvent. It may be a hot air drying furnace for evaporating. In addition, in the present Example, although the coating part 4 and the drying part 6 are provided as the coating device 2, the drying part 6 can also be set as an independent structure separately.

In the coating device 2, the sheet-shaped base material 20 wound in a roll shape is continuously drawn out and conveyed to the coating application part 4, and an electrode slurry (one surface) is formed on one surface (surface) of the sheet-shaped base material 20. 21) is apply | coated, conveyed to the drying part 6, and forced to dry, and then wound up in roll shape again. The electrode layer 22 is formed on one surface of the sheet-like base material 20 by a series of treatments by the coating device 2. In this embodiment of manufacturing the electrode foil, the electrode active material layer is formed on the metal foil by a series of treatments by the coating device 2. In addition, when forming the electrode layer 22 on both surfaces of the sheet-like base material 20, the same process as above is performed to the other surface (back surface) of the sheet-like base material 20, and the said sheet-like base material 20 is carried out. The electrode layer 22 can be formed on the other side of the substrate.

Subsequently, by the rolling apparatus not shown in figure, the sheet-like base material 20 wound by roll shape is continuously drawn out, it is pressed between rolling rolls, and it is wound up in roll shape again. By the press process by this rolling apparatus, the packing density of the electrode layer 22 formed in the sheet-like base material 20 increases. In the present Example which manufactures electrode foil, the metal foil in which the electrode active material layer was formed is pressed by the rolling apparatus, the packing density of the electrode active material of the said electrode active material layer becomes high, it becomes uniform, and becomes electrode foil.

Next, the structure of the coating part 4 of the said coating device 2 is demonstrated. As shown in FIG. 1, the coating part 4 of the coating device 2 has the backup roller 8 in which the sheet-shaped base material 20 was wound, and the sheet which passes on the said backup roller 8 top. The die coater 10 which apply | coats the electrode slurry 21 to the shape base material 20 is provided. Hereinafter, the width direction of the sheet-like base material 20 is defined as "width direction." Therefore, the direction substantially parallel to the axis | shaft of the backup roller 8 by which the sheet-shaped base material 20 was wound is the width direction.

In addition to the said backup roller 8, the said coating device 2 is equipped with the singular or several guide roller 14, and the sheet-like base material 20 is wound up with tension. By the rotation of these rollers 14, the sheet-shaped base material 20 wound up in roll shape is fed out to the application | coating construction part 4 continuously at a predetermined | prescribed speed, and further conveyed to the drying part 6, It is wound up in roll shape again.

The die coater 10 backs up the electrode slurry 21 supplied from the coating liquid tank 9 from the slit 11 (hereinafter also referred to as a “die coater head”) opened to the beak-shaped nozzle and backs up. It apply | coats to the sheet-like base material 20 on the roller 8. The slit 11 of the nozzle of the die coater 10 is elongate in the width direction of the sheet-like base material 20, and the electrode slurry 21 with respect to the sheet-like base material 20 with the opening width of the slit 11 The prescribed width to be applied is determined. Moreover, the die coater 10 can employ | adopt the existing die coater generally used widely.

The said backup roller 8 winds up the sheet-like base material 20 to which the electrode slurry 21 is apply | coated by the die coater 10, and receives the coating pressure from the die coater 10. FIG. The backup roller 8 is comprised with the driven roller which receives the tension of the sheet-like base material 20 conveyed by rotationally driving the guide roller 14 arrange | positioned upstream or downstream of the said backup roller 8, and rotates.

In the above configuration, the slit 11 of the die coater 10 is close to the sheet-shaped substrate 20 wound around the backup roller 8, and the specified width (the opening of the slit 11 of the die coater 10) Electrode slurry 21 is applied.

As shown in FIG. 2, the backup roller 8 is provided with a concave shape 8A for straightening the starting and ending lines of the electrode layer 22 formed on the sheet-like substrate 20. . That is, the surface shape of the said backup roller 8 is formed in the concave shape 8A which becomes a minimum diameter in the width direction center part, and whose diameter gradually increases as it moves to the width direction both sides. That is, it is set as the concave shape 8A which has the largest diameter in the width direction both sides of the said backup roller 8, and gradually reduces a diameter as it moves to the width direction center part.

For this reason, the sheet-shaped base material 20 wound by applying tension to the backup roller 8 is also most concave in the width direction center part along the outer periphery shape of the backup roller 8, and gradually becomes a diameter as it moves to both sides of the width direction. It is elastically deformed into this increased shape and wound on the backup roller 8.

Therefore, the surface of the sheet-shaped base material 20 is closest to the opening of the slit 11 at both ends of the width direction with respect to the opening of the slit 11 of the die coater 10, and the slit as it moves to the width direction center part. It is positioned so that the distance from the opening of 11 becomes gradually larger.

In the coating apparatus 2 of the above structure, when the high viscosity electrode slurry 21 flows out from the slit 11 of the die coater 10, the high viscosity electrode slurry 21 will be the wall surface of the slit 11. Slips out and spills. For this reason, at the time of outflow start, the increase of the outflow velocity from the both ends of the slit 11 width direction with the contact area with the slit 11 wall surface from the relatively small slit 11 width direction center part is relatively small. There is a delay compared to the rise of the outflow rate. That is, the outflow amount of the electrode slurry 21 with high viscosity which flows out from the slit 11 is the largest in the width direction center part of the slit 11, and the outflow amount of the electrode slurry 21 becomes small as it moves to the width direction both ends. Lose. For this reason, at the start of outflow, the shape of the tip portion of the electrode slurry 21 flowing out from the slit 11 is curved in a mountain shape that is highest in the width direction center part and gradually lowers as it moves to both width direction ends. Then, after reaching the prescribed speed at which the flow rate of the electrode slurry 21 flowing out while sliding in the slit 11 is reached, it flows out at the same speed in the center part and the both ends of the slit 11 width direction.

In front of the electrode slurry 21 provided with the tip of the mountain shape at the start of the outflow, the shape is most concave at the center in the width direction along the backup roller 8 and gradually increases in diameter as it moves to both sides in the width direction. There exists the surface of the sheet-like base material 20 which is elastically deformed. For this reason, as shown in FIG. 3, the front-end | tip part provided with the mountain-shaped front-end | tip part of the electrode slurry 21 reaches | attains substantially the same time in any area | region in the width direction of the surface of the sheet-like base material 20, and is sheet-like It is apply | coated to the surface of the base material 20 in linear form.

Since the outflow velocity of the subsequent electrode slurry 21 flows out at the same speed in the center part and the both ends of the slit 11 width direction, the electrode slurry 21 is uniformly uniform in the width direction on the surface of the sheet-like base material 20 ) Is applied.

In addition, when the outflow of the high viscosity electrode slurry 21 is stopped from the slit 11 of the die coater 10, that is, the extrusion by internal pressure is stopped, the outflow of the high viscosity electrode slurry 21 is stopped quickly. do. At the time of this outflow stop, in order to stop the extrusion force by the internal pressure of the die coater 10, the contact area with the slit 11 wall surface is relatively small, and the slit 11 with little braking by the slit 11 wall surface is small. Departure of the electrode slurry 21 from the width direction center part is preceded, and departure of the electrode slurry 21 from both ends of the slit 11 width direction which is relatively large and the braking by the slit 11 wall surface is delayed slightly.

For this reason, at the time of outflow stop, the rear end shape of the electrode slurry 21 which flowed out from the slit 11 is the lowest (concave) in the width direction center part, and gradually becomes rearward as it moves to both width direction ends. Bend. Application of the electrode slurry 21 having the rear end portion of the mountain shape is finished at approximately the same time in any region in the width direction of the surface of the sheet-like substrate 20, and is substantially linear on the surface of the sheet-like substrate 20. The application is finished.

In the above-described present embodiment, since a large diameter is provided on both sides in the width direction of the backup roller 8, and the diameter is gradually reduced as it moves to the width direction center part, the back shape is 8A. The sheet-like base material 20 wound up by applying tension to the roller 8 is also maintained in the same shape. For this reason, the application start shape and application | coating end shape to the surface of the sheet-form base material 20 were carried out with the electrode slurry 21 which has the shape of the tip end of the high viscosity acid flowed out from the slit 11 of the die coater 10. Can be made into a linear shape. For this reason, the application | coating start / end edge part can be used effectively as an electrode, and a yield can be improved, without cutting | disconnection and the like.

As mentioned above, although the coating device 2 and the manufacturing method of an electrode foil which concern on one Embodiment of this invention were demonstrated, the manufacturing method of the coating device 2 and electrode foil which concerns on this invention are not limited to embodiment mentioned above. Do not.

For example, FIG. 4, FIG. 5 shows the modification of this embodiment. In this modified example, the inner surface of the backup roller 8 is made into a cavity, and numerous holes 8B are formed innumerably to communicate the roller surface in the area where the inside of the cavity is in contact with the sheet-like substrate 20 wound up. The configuration in which air in the cavity is discharged by the air pump 16 is added to the embodiments shown in FIGS. 2 and 3. The said myriad fine hole 8B can also be comprised by forming the backup roller 8 itself by porous bodies, such as a ceramic. In addition, when the back-up roller 8 itself is comprised by metal or resin, it can comprise by forming the many hole 8B which penetrates in a cavity from the roller surface.

In this modification, the air on the roller surface is discharged through the fine and myriad holes 8B by discharging the air in the cavity of the backup roller 8 with the air pump 16. Therefore, the sheet-like base material 20 wound around the backup roller 8 is in a state of being in close contact with the roller surface. For this reason, it can prevent that the sheet-form base material 20 floats apart from the surface of the backup roller 8 formed in the concave shape 8A, and can apply | coat the electrode slurry 21 stably.

In addition, in another modified example of the present embodiment shown in FIG. 6, the inner surface of the backup roller 8 is made into a cavity, and the refrigerant from the cooling device 18 is supplied and circulated in the cavity to provide a backup roller 8. The structure which made surface temperature low temperature is added to the Example shown in FIG.

In this modification, the surface temperature of the backup roller 8 is made into the low temperature state lower than the temperature of the die coater head 11 and the electrode slurry 21 from which the electrode slurry 21 is discharged. For this reason, the temperature of the sheet-like base material 20 wound up to it can be reduced. For this reason, the temperature of the electrode slurry 21 apply | coated to the sheet-like base material 20 can be reduced quickly, the fluidity | liquidity is reduced, and the shape change as the applied electrode layer 22 can be suppressed.

In another modified example of this embodiment shown in FIG. 7, FIG. 8, the structure which simplified the concave shape 8A which comprises the surface of the backup roller 8 in FIG. 2, FIG. 3 is shown. I added it to the example.

That is, although the backup roller 8 is formed in the substantially cylindrical shape, it is made to form the annular protrusion 8C in the width direction both ends in the area | region where the sheet-like base material 20 is wound. For this reason, the area | region in which the sheet-like base material 20 of the backup roller 8 is wound is made into large diameter in the width direction both ends, and is simple concave shape 8A which becomes small diameter in the width direction center side. do. And when the sheet-shaped base material 20 is wound up in the state which tensioned the said backup roller 8, as shown in FIG. The diameter gradually decreases as it moves to the center region in the width direction.

Therefore, although the roller surface shape of the backup roller 8 is the recessed shape 8A with a level | step difference, the surface shape of the sheet-like base material 20 wound up is the same concave shape as shown in FIG. 2, FIG. It can be formed as.

In this embodiment, the effect described below can be exhibited.

(A) The die coater 10 which apply | coats the electrode slurry 21 to the backup roller 8 by which the sheet-shaped base material 20 was wound, and the sheet-shaped base material 20 conveyed on the said backup roller 8 image is carried out. It relates to the coating device 2 provided at least. And the outer diameter of the outer area which supports the both ends of the width direction of the sheet-like base material 20 wound up among the said backup rollers 8 is larger than the outer diameter of the center area | region sandwiched between the said outer areas 8A concave shape. ). Therefore, it is discharged from the die coater head 11, and is concave in the width direction center area | region by the backup roller 8 in the shape of the front-end | tip part of the electrode slurry 21 in which the width direction center part becomes convex with respect to the width direction both ends. The shape of the sheet-like base material 20 held in the shape 8A can be similar. For this reason, the distance between the front-end | tip part of the electrode slurry 21 from the die coater head 11, and the sheet-like base material 20 can be made equal at the center part and the edge part of the sheet-like base material 20, and was apply | coated. The curvature of the edge part of (22) can be reduced.

(B) In the coating apparatus 2 shown to FIG. 2, FIG. 3, the sheet-form base material 20 wound around the center area | region sandwiched between the outer area | region of the backup roller 8 from the outer diameter of the said outer area | region. It is set as 8A of concave shape which diameter reduces gradually toward the width direction center of the (). For this reason, in the shape of the front-end | tip part of the electrode slurry 21 discharged from the die coater head 11, and the width direction center part becomes convex with respect to the width direction both ends, in the width direction center area | region by the backup roller 8, The shape of the sheet-like base material 20 held in the concave shape can be more similar. For this reason, the distance between the front-end | tip part of the electrode slurry 21 from the die coater head 11, and the sheet-like base material 20 can be made equal at the center part and the edge part of the sheet-like base material 20, and the coated electrode The curvature of the edge part of can be made small.

(C) In the coating device 2 shown in FIG. 4, FIG. 5, many air suction holes opened in the area | region which the sheet-like base material 20 wound up contact with the outer periphery of the backup roller 8 ( The sheet-like substrate 20 is adsorbed on the surface of the backup roller 8 by discharging air between the sheet-like substrate 20 wound up through the air suction hole 8B. For this reason, it can prevent that the sheet-form base material 20 floats apart from the surface of the backup roller 8 formed in the concave shape 8A, and can apply | coat the electrode slurry 21 stably.

(D) In the coating apparatus 2 shown in FIG. 6, the backup roller 8 is the temperature of the electrode slurry 21 apply | coated to the sheet-like base material 20 by the cooling apparatus 18 as a cooling means. It is kept at a lower low temperature. For this reason, the temperature of the electrode slurry 21 apply | coated to the sheet-like base material 20 can be reduced, the fluidity | liquidity can be reduced, and the shape change as the applied electrode layer 22 can be suppressed.

(E) It is a manufacturing method of the electrode foil which apply | coats the electrode slurry 21 extruded from the die coater 10 to the sheet-like base material 20 wound up by the backup roller 8 and conveyed on the backup roller 8 image. And the electrode slurry 21 which extruded from the die coater 10 was hold | maintained in the concave shape 8A recessed rather than the both ends of the center part of the width direction of the sheet-like base material 20 wound by the said backup roller 8, and extruded from the die coater 10. FIG. ) Is applied. Therefore, it is discharged from the die coater head 11, and is concave in the width direction center area | region by the backup roller 8 in the shape of the front-end | tip part of the electrode slurry 21 in which the width direction center part becomes convex with respect to the width direction both ends. The shape of the sheet-like base material 20 held in the shape can be similar. For this reason, the distance between the front-end | tip part of the electrode slurry 21 from the die coater head 11, and the sheet-like base material 20 can be made equal at the center part and the edge part of the sheet-like base material 20, and was apply | coated. The curvature of the edge part of (22) can be reduced.

2: coating device
4 coating part
6: drying part
8: backup roller
8A: concave shape
10: die coater
11: slit, die coater head
20: sheet-shaped base material
21: electrode slurry
22: electrode layer

Claims (5)

A coating device comprising at least a backup roller on which a sheet-shaped substrate is wound and a die coater for applying an electrode slurry to the sheet-shaped substrate conveyed on the backup roller.
The outer diameter of the outer side area | region which supports the both ends of the width direction of the sheet-like base material wound up among the said backup rollers was made larger concave shape than the outer diameter of the center area | region sandwiched between the said outer area | regions, The coating apparatus characterized by the above-mentioned. . The method of claim 1,
A coating device, wherein the central region sandwiched between the outer regions of the backup roller is a concave shape whose diameter is gradually reduced from the outer diameter of the outer region toward the center in the width direction of the sheet-like substrate to be wound. . The method according to claim 1 or 2,
The outer periphery of the said back-up roller is equipped with many air suction holes opened in the area | region which the sheet-like base material wound up contact, and discharges the air between the sheet-shaped base materials wound up through the air suction hole, To a surface of the back up roller, wherein the coating device is applied. The method according to claim 1 or 2,
The said back-up roller is hold | maintained at low temperature state lower than the temperature of the electrode slurry apply | coated to a sheet-like base material by a cooling means, The coating apparatus characterized by the above-mentioned. As a manufacturing method of the electrode foil which apply | coats the electrode slurry extruded from the die coater to the sheet-like base material wound up by a backup roller and conveyed a backup roller image,
A method for producing an electrode foil, wherein the center portion in the width direction of the sheet-like base material wound by the backup roller is held in a concave shape that is dented from both ends, and the electrode slurry extruded from the die coater is applied.

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