JP2016072200A - Method of defoaming electrode paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of defoaming an electrode paste by which an electrode paste with a high solid component rate can be defoamed effectively.SOLUTION: The present invention relates to a method of defoaming an electrode paste P including an electrode active material and a dispersant, and having a solid component rate of 59 mass% or larger. A defoaming apparatus 100 is used, which comprises a container 110, and a rotation body 120 provided in the container 110, and having a horizontal part 121; a distance by which the rotation body 120 is spaced apart from the inner wall surface 112S of the container 110 is 200 mm or less. The method comprises: a defoaming step of performing a defoaming process of the electrode paste P by: supplying the electrode paste P onto the horizontal part 121 of the rotation body 120 so as to be in a film-like form; and scattering the supplied electrode paste P in the film-like form from the horizontal part 121 toward the inner wall surface 112S of the container 110. In the defoaming step, the shear rate of an outermost peripheral end 120E of the rotation body 120 is within a range of 7×10to 2×10s.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for defoaming an electrode paste.

Nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries are used in hybrid vehicles (HV), plug-in hybrid vehicles (PHV), electric vehicles (EV), and the like.
A nonaqueous electrolyte secondary battery includes a positive electrode and a negative electrode that are a pair of electrodes, a separator that insulates between them, and a nonaqueous electrolyte.
As a structure of an electrode (positive electrode or negative electrode) for a non-aqueous electrolyte secondary battery, a structure including a current collector made of a metal foil or the like and an electrode active material layer including an electrode active material formed thereon is known. ing.

The positive electrode active material layer includes, for example, a positive electrode active material such as a lithium-containing composite oxide, a conductive assistant such as carbon powder, a binder such as polyvinylidene fluoride (PVDF), and N-methyl-2-pyrrolidone (NMP). A paste containing a dispersion medium is applied onto a current collector such as an aluminum foil, dried, and pressed to form.
The negative electrode active material layer includes, for example, a negative electrode active material such as graphite, a binder such as modified styrene-butadiene copolymer latex (SBR), a thickener such as carboxymethyl cellulose Na salt (CMC), and a dispersion medium such as water. The paste containing is applied onto a current collector such as copper foil, dried, and pressed to form.

Usually, the above-mentioned electrode paste is manufactured by mixing the active material and other solid components, and then kneading the obtained mixed powder and a dispersion medium such as NMP or water.
The electrode paste after kneading usually contains bubbles. If the electrode paste containing bubbles is applied as it is onto the current collector, the active material or the like is not applied to the bubble portions, resulting in defects. Therefore, a defoaming step for removing bubbles in the electrode paste is performed after the kneading step.

Considering the improvement in energy density, the electrode active material layer is preferably a thick film and a high density. In order to achieve a thicker and higher density electrode active material layer, higher solid content of electrode pastes has been studied.
The electrode paste has a tendency that the higher the solid content is, the more the viscosity increases and it is difficult for bubbles to escape. In particular, it is difficult to defoam an electrode paste having a high solid content of 59% by mass or more.
In the present specification, unless otherwise specified, the “high solid content” is defined as 59% by mass or more.

  Conventionally, there is a vacuum defoaming method for an electrode paste in which an electrode paste is gradually put into an inside of a vacuum tank and defoamed in a stationary state. However, since the electrode paste having a high solid content has a high viscosity, it is difficult for bubbles to rise even under a high vacuum, and it is difficult to effectively remove the bubbles.

  As a general liquid defoaming method, there is a centrifugal defoaming method in which gas-liquid separation is performed using centrifugal force. However, if this method is applied to an electrode paste in which high-density particles are dispersed, the specific gravity difference between the high-density particles and the dispersion medium is large, resulting in paste separation in which the high-density particles settle.

  In Patent Document 1, the negative electrode gel is continuously dropped into the decompression container, and is collided with a disk that rotates substantially horizontally inside the container to be scattered on the inner wall surface of the container side, along the inner wall surface. A negative electrode gel manufacturing method is disclosed, in which the gel flowing down is collected in a funnel-shaped portion and continuously discharged by a pump from the lower portion of the funnel-shaped portion (Claim 1).

JP 2004-171918 A

The method described in Patent Document 1 has the following problems.
With high solid content electrode paste, when the shear rate at the outermost peripheral edge of the disk is low, it is difficult to disperse the electrode paste to the inner wall of the side of the container, and stable bubble breakage using collision with the inner wall It is difficult to implement it.
When the shear rate at the outermost peripheral edge of the disk is high, the electrode paste can be scattered to the inner wall surface of the container side, but when the electrode paste collides with the inner wall surface, foaming occurs and the defoaming is the original purpose. Is difficult to implement stably.

  This invention is made | formed in view of the said situation, and it aims at providing the defoaming method of the electrode paste which can defoam the electrode paste of a high solid content rate effectively. is there.

The defoaming method of the electrode paste of the present invention is:
A method for defoaming an electrode paste containing an electrode active material and a dispersion medium and having a solid content of 59% by mass or more,
A defoaming device having a container and a rotating body provided inside the container and having a horizontal portion, and having a separation distance of 200 mm or less between the rotating body and the inner wall surface of the container,
Supplying the electrode paste on the horizontal portion of the rotating body in a film shape, scattering the electrode paste supplied in a film shape from the horizontal portion to the inner wall surface of the container, Having a defoaming step for defoaming the electrode paste;
In the defoaming step, the shear rate of the outermost peripheral end of the rotating body is set within a range of 7 × 10 ⁵ to 2 × 10 ⁶ s ⁻¹ .

  ADVANTAGE OF THE INVENTION According to this invention, the defoaming method of the electrode paste which can defoam the electrode paste of a high solid content rate effectively can be provided.

It is a schematic whole view which shows the structural example of a nonaqueous electrolyte secondary battery. It is a schematic cross section of an electrode laminated body. It is a schematic cross section of an electrode. It is a figure which shows typically the deaeration apparatus of one Embodiment which concerns on this invention, and the installation of the front | former stage and back | latter stage. In Example 1, it is a graph which shows the relationship between the shear rate of the outermost periphery end of a rotary body, and the number of bubbles (total number of bubbles) in the paste after defoaming. In Example 2, it is a graph which shows the number of the bubbles of 0.3 micrometer or more in three conditions before defoaming, before defoaming before filter filtration, and after filter filtration.

"Nonaqueous electrolyte secondary battery"
1 to 3 show configuration examples of the nonaqueous electrolyte secondary battery. 1 is a schematic overall view, FIG. 2 is a schematic cross-sectional view of an electrode laminate, and FIG. 3 is a schematic cross-sectional view of an electrode.

A non-aqueous electrolyte secondary battery 1 shown in FIG. 1 is one in which an electrode laminate 30 and a non-aqueous electrolyte (not shown) are accommodated in an exterior body (battery container) 11.
As shown in FIG. 2, the electrode laminate 30 is obtained by laminating a positive electrode 21 and a negative electrode 22 with a separator 31 insulating them.
Two external terminals (a plus terminal and a minus terminal) 12 for external connection are provided on the outer surface of the exterior body 11.
As shown in FIG. 3, the electrode 20 (positive electrode 21 or negative electrode 22) is obtained by forming an electrode active material layer 20B on a current collector 20A. The electrode active material layer 20B is provided on one side or both sides of the current collector 20A. FIG. 3 shows an example in which the electrode active material layer 20B is provided on one surface of the current collector 20A.

The positive electrode active material layer includes, for example, a positive electrode active material such as a lithium-containing composite oxide, a conductive assistant such as carbon powder, a binder such as polyvinylidene fluoride (PVDF), and N-methyl-2-pyrrolidone (NMP). A paste containing a dispersion medium is applied onto a current collector such as an aluminum foil, dried, and pressed to form.
The negative electrode active material layer includes, for example, a negative electrode active material such as graphite, a binder such as modified styrene-butadiene copolymer latex (SBR), a thickener such as carboxymethyl cellulose Na salt (CMC), and a dispersion medium such as water. The paste containing is applied onto a current collector such as copper foil, dried, and pressed to form.

"Electrode paste defoaming device and defoaming method"
The present invention relates to a method for defoaming an electrode paste (electrode paste having a high solid content) having a solid content of 59% by mass or more containing an electrode active material and a dispersion medium.
The present invention is applicable to both positive electrode pastes and negative electrode pastes.

With reference to drawings, the defoaming apparatus and defoaming method of the paste for electrodes of one embodiment concerning the present invention are explained.
FIG. 4 is a diagram schematically showing the defoaming device and its front and rear equipment.
In FIG. 4, the code | symbol 100 shows the defoaming apparatus of this embodiment. The defoaming device 100 in FIG. 4 is a schematic longitudinal sectional view.

  As shown in FIG. 4, the defoaming device 100 of this embodiment includes a container 110 and a rotating body 120 provided inside the container 110.

In this embodiment, the container 110 is a sealable tank, and includes a tank main body (not shown) having a funnel-shaped lower portion 111 and a cylindrical side portion 112 and an upper opening, and the opening of the tank main body is closed. And a lid member 113 to be used.
The container 110 has a paste charging portion (specific illustration and reference not shown) such as a charging nozzle for the electrode paste P in the lid member 113, and an outlet 111 </ b> M for the electrode paste P in the lower portion 111.

The container 110 is preferably a decompression device, and particularly preferably a vacuum container.
In the illustrated example, the container 110 is a vacuum tank, and a vacuum device Vac. It is connected to the.

The rotating body 120 has at least a horizontal portion 121.
In the present embodiment, the rotator 120 is a dish-like rotator that includes a horizontal portion 121 and side portions 122 that extend obliquely upward outward from the horizontal portion 121 and has an upper opening.
The shape of the rotating body 120 is not particularly limited as long as it has at least the horizontal portion 121, and may be a disk or the like.

A motor 124 is provided on the lid member 113 of the container 110, and the motor 124 and the center of the horizontal portion 121 of the rotating body 120 are connected via a motor shaft 123.
The rotating body 120 rotates about the motor shaft 123 as a rotation axis by driving the motor 124.
In the container 110, the rotating body 120 is provided above the center height of the side portion 112 (closer to the lid member 113).

In FIG. 4, reference numeral 200 schematically indicates a front-stage device provided in the front stage of the defoaming apparatus 100. The pre-stage device 200 is a kneading device or a storage device for the electrode paste P.
The electrode paste P is supplied from the upstream apparatus 200 to the defoaming apparatus 100 via a pipe or the like.
In this embodiment, the electrode paste P is an electrode paste having a solid content of 59% by mass or more (an electrode paste having a high solid content) including an electrode active material and a dispersion medium.
The electrode paste P is a positive electrode paste or a negative electrode paste.

The electrode paste P supplied from the pre-stage device 200 for the electrode paste P is put into a rotating body 120 provided inside the container 110 via a paste input unit (specific illustration and reference not shown) such as an input nozzle. Supplied.
In FIG. 4, a path for supplying the electrode paste P from the pre-stage apparatus 200 to the defoaming apparatus 100 and further putting it into the rotating body 120 is schematically shown by arrows.

The electrode paste P is, for example, charged obliquely downward from a paste charging part such as a charging nozzle according to the inclination angle of the side part 122 of the rotating body 120 and supplied onto the horizontal part 121 of the rotating body 120.
The electrode paste P is formed into a film on the horizontal portion 121, climbs up inside the rotating body 120 along the side portion 122 by a centrifugal action caused by the rotation of the rotating body 120, is released to the outside of the rotating body 120, and is scattered. Furthermore, the electrode paste P collides with the inner wall surface 112S of the side portion 112 of the container 110, flows down along the inner wall surface 112S, and moves toward the outlet 111M.
In FIG. 4, the path after the electrode paste P is put into the defoaming apparatus 100 is also schematically indicated by arrows.

The defoaming method of this embodiment is
The electrode paste P is supplied in a film shape onto the horizontal portion 121 of the rotating body 120, and the electrode paste supplied in a film shape from the horizontal portion 121 to the inner wall surface 112S of the container 110 by the rotating action of the rotating body 120. It has a defoaming step in which P is scattered to defoam the electrode paste P.

In the present embodiment, in the defoaming step, the bubbles are ruptured by the collision action on the inner wall surface 112S to break the bubbles.
In the present embodiment, the electrode paste P is supplied in a film form on the horizontal portion 121 of the rotating body 120, and is scattered little by little to collide with the inner wall surface 112S. Therefore, the electrode paste P having a high solid content and high viscosity is used. Can also be effectively degassed.

In the present embodiment, the separation distance between the rotating body 120 and the inner wall surface 112S of the container 110 is designed so that the electrode paste P supplied into the rotating body 120 stably collides with the inner wall surface 112S of the container 110. Is done.
From the above viewpoint, the separation distance between the rotating body 120 and the inner wall surface 112S of the container 110 is set to 200 mm or less.

Further, in the present embodiment, in the defoaming step, the shear rate of the outermost peripheral end 120E of the rotating body 120 is set in the range of 7 × 10 ⁵ to 2 × 10 ⁶ s ⁻¹ .

  The “shear rate of the outermost peripheral end of the rotating body of an arbitrary shape” is determined by a known method from the maximum diameter of the outermost peripheral end of the rotating body, the planar view shape of the outermost peripheral end of the rotating body, and the rotational speed of the rotating body. Is required.

In the electrode paste P having a high solid content, when the shear rate of the outermost peripheral end 120E of the rotating body 120 is too low, it is difficult to scatter the electrode paste P to the inner wall surface 112S of the container 110, and the collision with the inner wall surface 112S occurs. It is difficult to stably carry out foam breaking using
In the electrode paste P having a high solid content, when the shear rate of the outermost peripheral end 120E of the rotating body 120 is excessive, the electrode paste P can be scattered to the inner wall surface 112S of the container 110. Bubbles when they collide with the inner wall surface 112S, and it is difficult to stably carry out the defoaming which is the original purpose.

Also in the electrode paste P with a high solid content, the electrode paste P is placed in a container by setting the shear rate of the outermost peripheral end 120E of the rotating body 120 within the range of 7 × 10 ⁵ to 2 × 10 ⁶ s ^−1. The inner wall surface 112S of 110 can be stably scattered. Moreover, foaming when the electrode paste P collides with the inner wall surface 112S can be satisfactorily suppressed.
For the relationship between the shear rate of the outermost peripheral end 120E of the rotating body 120 and the number of bubbles after defoaming, refer to the section “Examples” below and FIG.

  In the present embodiment, combined with the above-described effects, defoaming can be effectively performed even in the electrode paste P having a high solid content.

In the present embodiment, the case where the container 110 is a vacuum tank has been described.
The pressure in the container 110 is not particularly limited, and may be normal pressure or reduced pressure.
In the present embodiment, the defoaming is mainly performed by using the collision action of the electrode paste P against the inner wall surface 112S, so that the defoaming can be performed even if the inside of the container 110 is at normal pressure.
However, the pressure in the container 110 is preferably a reduced pressure, and more preferably a vacuum pressure, since the bubbles are easily expanded and burst at the time of collision.
The pressure in the container 110 is preferably in the range of 0 to -100 kPa, for example.
Basically, the higher the degree of vacuum (vacuum), the more likely that the bubbles will expand and burst when colliding. However, depending on the vacuum pressure, new bubbles may be generated due to the release of dissolved oxygen.
Therefore, it is preferable to set the degree of vacuum (degree of vacuum) within a range that does not affect the generation of new bubbles due to the release of dissolved oxygen.
In the present specification, unless otherwise specified, the “decompression degree (vacuum degree)” is expressed as a gauge pressure.

In FIG. 4, reference numeral 300 schematically indicates a filter provided in the subsequent stage of the defoaming apparatus 100. A known filtration filter can be used as the filter 300.
In FIG. 4, reference numeral 400 schematically indicates a coating apparatus provided at the subsequent stage of the filter 300. The coating apparatus 400 is a coating die or the like that coats the electrode paste P on the current collector.

As described above, it is preferable that the electrode paste P after defoaming is further supplied to the coating apparatus 400 via the filter 300.
The electrode paste P after the defoaming step may contain a small amount of bubbles or various foreign substances. By subjecting the electrode paste P after the defoaming step to pressure filtration using the filter 300, a small amount of remaining bubbles or various foreign matters can be removed, which is preferable.

  As described above, according to this embodiment, it is possible to provide a method for defoaming an electrode paste P that can effectively defoam an electrode paste P having a high solid content.

"Nonaqueous electrolyte secondary battery"
Examples of the non-aqueous electrolyte secondary battery include a lithium ion secondary battery.
Hereinafter, main components will be described by taking a lithium ion secondary battery as an example.

(Positive electrode)
The positive electrode can be manufactured by applying a positive electrode active material to a positive electrode current collector such as an aluminum foil by a known method.
Known no particular limitation on the positive electrode active material, for _{example, LiCoO 2, LiMnO 2, LiMn} 2 O 4, LiNiO 2, LiNi x Co (1-x) O 2, and _{LiNi x Co y Mn (1-} x-y _And lithium-containing composite oxides such as O ₂ (where 0 <x <1, 0 <y <1).
The method for producing the positive electrode is as described above.

(Negative electrode)
The negative electrode active material is not particularly limited, and a material having a lithium storage capacity of 2.0 V or less on the basis of Li / Li + is preferably used. As the negative electrode active material, carbon such as graphite, metallic lithium, lithium alloy, transition metal oxide / transition metal nitride / transition metal sulfide capable of doping / dedoping lithium ions, and these A combination etc. are mentioned.
The method for producing the negative electrode is as described above.

(Non-aqueous electrolyte)
As the non-aqueous electrolyte, known ones can be used, and liquid, gel-like or solid non-aqueous electrolytes can be used.
For example, a lithium-containing electrolyte is dissolved in a mixed solvent of a high dielectric constant carbonate solvent such as propylene carbonate or ethylene carbonate and a low viscosity carbonate solvent such as diethyl carbonate, methyl ethyl carbonate, or dimethyl carbonate. A water electrolyte is preferably used.

As the mixed solvent, for example, a mixed solvent such as ethylene carbonate (EC) / dimethyl carbonate (DMC) / ethyl methyl carbonate (EMC) and ethylene carbonate (EC) / diethyl carbonate (DEC) is preferably used.
Examples of the lithium-containing electrolyte include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiOSO ₂ C _k F _{(2k + 1)} (k = 1 to 8), LiPF _n {C _k F _{(2k + 1) )} (6-n) (} n = 1~5 integer, k = 1 to 8 integer) lithium salts such as, and combinations thereof.

(Separator)
The separator may be a film that electrically insulates the positive electrode and the negative electrode and is permeable to lithium ions, and a porous polymer film is preferably used.
As the separator, for example, a porous film made of polyolefin such as a porous film made of PP (polypropylene), a porous film made of PE (polyethylene), or a laminated porous film of PP (polypropylene) -PE (polyethylene) is preferably used. It is done.

(Exterior body (battery container))
A well-known thing can be used as an exterior body.
As a type of the secondary battery, there are a cylindrical type, a coin type, a square type, a film type (laminate type), and the like, and an exterior body can be selected according to a desired type.

  In addition, this invention is applicable not only to a nonaqueous electrolyte secondary battery but the manufacture of the paste for electrodes of arbitrary uses.

  Embodiments according to the present invention will be described.

[Method for measuring the number of bubbles]
In the following Examples 1 and 2, the number of bubbles in the electrode paste was measured by the following procedure.
A 10 cc paste was passed through a gap between a pair of opposed glass plates spaced apart from each other, and a photo was taken with an optical camera from one glass plate side.
The number of bubbles per 10 cc was determined by performing image analysis on the obtained photograph by a known method.
As the number of bubbles, the total number of bubbles and / or the number of bubbles of 0.3 μm or more was determined.

Example 1
In Example 1, a negative electrode paste was prepared.
As materials, graphite as a negative electrode active material, carboxymethyl cellulose Na salt (CMC) as a thickener, modified styrene-butadiene copolymer latex (SBR) as a binder solution, and water as a dispersion medium were prepared. .
The material mixing ratio of the solid content was graphite / CMC / SBR = 98.6 / 0.7 / 0.7 (solid content mass ratio).
The solid content of the paste was 60% by mass.
The paste temperature was 20 ° C.
The viscosity of the paste was 14812.5 mPa · s.

  Using the defoaming apparatus 100 having the structure shown in FIG. 4, the negative electrode paste was defoamed. A vacuum tank was used as the container 110. The inner diameter of the vacuum tank was 300 mmφ.

  The supply speed of the electrode paste to the horizontal portion 121 of the rotating body 120 and the extraction speed from the outlet 111M were both 1.4 L / min.

  As the rotating body 120, a dish-shaped rotating body including a horizontal portion 121 and a side portion 122 extending obliquely upward outward from the horizontal portion 121 and having an open top is used. The plate thickness of the horizontal part 121 and the side part 122 was 2 mm. The inclination angle of the side portion 122 with respect to the horizontal portion 121 was 60 °.

Defoaming was performed under a plurality of conditions by changing the lower diameter (outer diameter of the bottom surface) and height of the rotating body 120 and the number of rotations of the rotating body 120.
In any condition, the separation distance between the rotating body 120 and the inner wall surface 112S of the container 110 was 200 mm or less.
In any conditions, the vacuum pressure inside the tank was -90 kPa.

Table 1 shows the main defoaming conditions.
In Table 1, “shear rate” is the shear rate of the outermost peripheral end 120 </ b> E of the rotating body 120.
Conditions other than those listed in the table were common conditions (the same applies to Example 2 described later).

In the table, the dimension of the rotating body 120 is represented as φ150 × 45. 150φ × 45 means a lower diameter of 150 mmφ and a height of 45 mm (the same applies to Example 2 described later).
In the table, the shear rate is 3.6. E + 05 and so on. 3.6. E + 05 means 3.6 × 10 ⁻⁵ (the same applies to Example 2 described later).

The defoamed paste was taken out from the outlet 111M, and the total number of bubbles was measured.
The results are shown in Table 1.

FIG. 5 shows the relationship between the shear rate of the outermost peripheral end 120E of the rotating body 120 and the total number of bubbles in the paste after defoaming.
FIG. 5 shows that the defoaming can be effectively performed by setting the shear rate of the outermost peripheral end 120 </ b> E of the rotating body 120 within the range of 7 × 10 ⁵ to 2 × 10 ⁶ s ⁻¹ . .
By setting the shear rate of the outermost peripheral end 120E of the rotating body 120 within the range of 7 × 10 ⁵ to 2 × 10 ⁶ s ⁻¹ , the total number of bubbles could be reduced to about 200/10 cc or less.
If the shear rate of the outermost peripheral end 120E of the rotator 120 is less than 7 × 10 ⁵ s ⁻¹ , it is considered that the scattering force of the paste on the inner wall surface of the vacuum tank is weak and effective defoaming is difficult.
When the shear rate of the outermost peripheral end 120E of the rotating body 120 exceeds 2 × 10 ⁶ s ⁻¹ , the impact force of the paste against the inner wall surface of the vacuum tank is strong, and as a result of foaming, it is considered that effective defoaming is difficult. .

(Example 2)
In Example 2, the same negative electrode paste as in Example 1 was prepared.
Using the same defoaming apparatus 100 as in Example 1, the negative electrode paste was defoamed.
As the container 110, the same vacuum tank having an inner diameter of 300 mmφ as that in Example 1 was used.
The supply speed of the electrode paste to the horizontal portion 121 of the rotating body 120 and the extraction speed from the extraction port 111M were the same as in Example 1.

As the rotating body 120, the φ150 × 45 dish-shaped rotating body of Example 1 was used. The rotation speed was 1500 rpm. The separation distance between the rotating body 120 and the inner wall surface 112S of the container 110 was 200 mm or less.
The vacuum pressure inside the tank was −40 kPa.

  In Example 2, after defoaming of the negative electrode paste using the defoaming apparatus 100, pressure filtration was further performed using a depth filter (resin filter, average opening diameter 50 μm).

For three conditions before defoaming, after defoaming, before filter filtration, and after filter filtration (after 6 minutes of filtration time), the number of bubbles of 0.3 μm or more was measured.
The number of bubbles of 0.3 μm or more is preferably 200/10 cc or less because poor coating can be suppressed in the subsequent process.

Main defoaming conditions and evaluation results are shown in Table 2 and FIG.
In Table 2, “shear rate” is the shear rate of the outermost peripheral end 120 </ b> E of the rotating body 120.

Before defoaming, the number of bubbles of 0.3 μm or more greatly exceeded 200/10 cc, but after defoaming (before filter filtration), the number of bubbles of 0.3 μm or more was less than 200/10 cc, After 6 minutes of filter filtration, the number of bubbles of 0.3 μm or more became zero.
The filter filtration pressure after 6 minutes from the start of filter filtration was 0.094 MPa.

  It was shown that by using the defoaming apparatus 100, defoaming conditions can be optimized, and defoaming can be satisfactorily performed. Further, by performing filter filtration, bubbles can be completely removed.

  The present invention is not limited to the above-described embodiments and examples, and can be appropriately modified without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Nonaqueous electrolyte secondary battery 11 Exterior body 20 Electrode 20A Current collector 20B Electrode active material layer 21 Positive electrode 22 Negative electrode 30 Electrode laminated body 31 Separator 100 Defoamer 110 Container 111 Lower part 111M Outlet 112 Side part 112S Inner wall surface 113 Cover Material 120 Rotating body 120E Outermost peripheral end 121 of rotating body Horizontal portion 122 Side portion 123 Motor shaft 124 Motor 300 Filter P Electrode paste Vac. Vacuum equipment

Claims (1)

A method for defoaming an electrode paste containing an electrode active material and a dispersion medium and having a solid content of 59% by mass or more,
A defoaming device having a container and a rotating body provided inside the container and having a horizontal portion, and having a separation distance of 200 mm or less between the rotating body and the inner wall surface of the container,
Supplying the electrode paste on the horizontal portion of the rotating body in a film shape, scattering the electrode paste supplied in a film shape from the horizontal portion to the inner wall surface of the container, Having a defoaming step for defoaming the electrode paste;
In the defoaming step, the shear rate of the outermost peripheral end of the rotating body is set within a range of 7 × 10 ⁵ to 2 × 10 ⁶ s ⁻¹ .
Defoaming method for electrode paste.

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