JP2003331829A - Method of manufacturing secondary battery electrode, secondary battery electrode, and secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a secondary battery electrode having less variation in the thickness of an electrode film after film formation and excellent diffusion of solid matter by properly maintaining the fluidity of the slurry. <P>SOLUTION: In this method of manufacturing the secondary battery electrode for forming the electrode film on a collector with electrode active material and conductive assistant material by applying, onto the collector, the slurry formed by mixing the electrode active material, conductive assist material, binder, and dispersion medium with each other. The yield point of the slurry before applied onto the collector is within the range of 1 to 250 Pa. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing an electrode for a secondary battery, an electrode for a secondary battery, and a secondary battery.

[0002]

2. Description of the Related Art Conventionally, an electrode of a secondary battery represented by a lithium ion secondary battery is formed by forming an electrode film on a current collector made of, for example, a metal foil. The electrode film is obtained by, for example, solidifying electrode active material powder and conductive auxiliary material powder into a film with a binder such as fluororesin.

Generally, in order to manufacture the above-mentioned electrode, for example, an electrode active material powder, a conductive auxiliary material powder, and a binder are added and mixed into a dispersion medium to form a slurry, and the slurry is applied to the current collector. However, means for heating and drying the slurry is adopted.

[0004]

By the way, in the conventional method of manufacturing an electrode, in order to suppress energy consumption during heating and drying of the slurry, the volume of solid content (electrode active material, conductive auxiliary material) contained in the slurry is reduced. Attempts have been made to increase the concentration to reduce the amount of the dispersion medium, thereby reducing the heating temperature and the heating time during drying as much as possible. However, when the amount of the dispersion medium added is reduced, there is a problem that the fluidity of the slurry decreases and the slurry cannot be uniformly applied to the current collector.

Further, in the conventional electrode manufacturing method, the solid content may be aggregated to form a granular aggregate when the slurry is formed, and this aggregate may be applied to the current collector together with the slurry. In this case, irregularities due to aggregates are generated on the surface of the electrode film, and even if the irregularities pierce the separator during battery production, they may come into contact with one of the electrodes and cause a short circuit. In addition, there is a problem that the dispersibility of the solid content cannot be made uniform due to the formation of aggregates.

The present invention has been made in view of the above circumstances. An electrode film having a constant film thickness can be obtained by maintaining the fluidity of a slurry appropriately, and the solid content is excellent in dispersibility. Another object of the present invention is to provide a method for manufacturing an electrode for a secondary battery. Further, the present invention provides an electrode for a secondary battery having a uniform film thickness and excellent flatness of the film surface, and due to the excellent dispersibility of solid content, occurrence of short circuit between electrodes after assembly. It is an object of the present invention to provide a secondary battery with reduced power consumption.

[0007]

Viscosity is a representative index showing the fluidity of a slurry, but the present inventors have paid attention to the yield value as an index instead of the viscosity, and set this yield value to an appropriate value. By setting the above-mentioned value, it was found that an electrode film having a uniform fluidity can be formed while the fluidity of the slurry is optimized and the dispersibility is excellent, and the present invention has been completed. That is, the present invention adopts the following configurations in order to achieve the above object.

In the method for manufacturing an electrode for a secondary battery of the present invention, a slurry obtained by mixing an electrode active material, a conductive auxiliary material, a binder and a dispersion medium is applied to a current collector, and then the dispersion medium is applied. In the manufacturing method of the secondary battery electrode, wherein the electrode film made of the electrode active material, the conductive material and the binder is formed on the current collector by removing the electrode active material, the yield value of the slurry is 1 It is characterized by being in the range of up to 250 Pa.

According to the method of manufacturing an electrode for a secondary battery,
The yield value, which is one of the indicators of the fluidity of the slurry, is 1 to
Since it is in the range of 250 Pa and the fluidity of the slurry is maintained at an appropriate level, the slurry does not run off from the current collector immediately after the application of the slurry or the application of the slurry becomes impossible. As a result, a secondary battery electrode having an electrode film with a constant film thickness can be manufactured. It should be noted that the yield value means that when shear stress is applied to a fluid material such as slurry or viscosity,
It is the stress value at which the flow starts and the unit is Pa (Pascal). The yield value is an important parameter when an electrode film with a thickness of several tens to hundreds of μm is formed smoothly, such as a battery electrode. If it is too high, the leveling cannot be performed and the yield is reduced. Will flow and impair the sharpness of the edges.

The method for producing an electrode for a secondary battery according to the present invention is the method for producing an electrode for a secondary battery described above, wherein the volume fraction of the electrode active material and the conductive auxiliary material in the slurry is large. Is in the range of 40 to 80% by volume.

According to the manufacturing method of the secondary battery electrode,
The volume fraction of the electrode active material and the conductive additive is 40 to 80% by volume.
Slurry yield value of 1 to 250
The range of Pa can be set, and an electrode for a secondary battery having an electrode film with a constant film thickness can be manufactured.

Further, in the method for producing an electrode for a secondary battery of the present invention, (total surface area of solid particles in slurry) /
The value of (volume of slurry) is 3 × 10 ⁵ to 15 × 10 ⁵ m ⁻¹
It is preferable to use a slurry having a range of.

Here, the solid particles in the slurry in the above formula mean the electrode active material and the conductive auxiliary material. Generally, the positive electrode contains a conductive aid such as carbon black, but the negative electrode may not contain it. Therefore, the total surface area of the solid particles in the slurry is the total surface area of the electrode active material and the conductive auxiliary material.

According to the manufacturing method of the secondary battery electrode,
By setting the value of (total surface area of solid particles in slurry) / (volume of slurry) to 3 × 10 ⁵ to 15 × 10 ⁵ m ⁻¹ , the slurry yield value is set to 1 to 250 Pa. It is possible to manufacture an electrode for a secondary battery having an electrode film with a constant film thickness.

The method for producing an electrode for a secondary battery of the present invention is the method for producing an electrode for a secondary battery as described above, wherein the particle size of the agglomerates contained in the electrode film is the film thickness of the electrode film. Of 50
It is characterized in that the slurry is mixed until it becomes less than or equal to%.

According to the method of manufacturing an electrode for a secondary battery, the slurry is mixed until the particle size of the aggregate contained in the electrode film becomes 50% or less of the film thickness of the electrode film. The unevenness is reduced and the flatness of the electrode film surface is improved,
A short circuit with the other electrode can be prevented. Further, by setting the particle size of the aggregate to 50% or less of the film thickness of the electrode film, the aggregate itself is reduced, the dispersibility of the solid content in the slurry is improved, and the dispersibility of the solid content of the electrode film is improved. Can be improved.

Since the electrodes obtained by these manufacturing methods have a constant film thickness and little unevenness, the performance of the secondary battery after stacking or winding the positive and negative electrodes is stable and the yield is improved.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a secondary battery that is an embodiment of the present invention. The secondary battery 1 is of a so-called prismatic type, and has a plurality of positive electrodes (electrodes) 2.
, A plurality of negative electrode electrodes 3, a separator 4 disposed between the positive electrode electrode 2 and the negative electrode electrode 3, and a nonaqueous electrolytic solution (nonaqueous electrolyte). Positive electrode 2
, The negative electrode 3, the separator 4, and the non-aqueous electrolyte are housed in a battery case 5 made of stainless steel or the like. A sealing plate 6 is attached to the upper part of the battery case 5. In addition, a safety valve 9 for preventing the internal pressure of the battery from rising is provided almost at the center of the sealing plate 6.

A positive electrode tab 12 is formed at one end of the positive electrode 2 and the positive electrode tab 12 is formed on the positive electrode tab 12a.
A positive electrode lead 12b for connecting a ... Is attached. A positive electrode terminal 7 penetrating the sealing plate 6 is attached to the positive electrode lead 12b. Similarly, the negative electrode 3 ...
Is formed at one end of the negative electrode tab 13a.
A negative electrode lead 13b for connecting the negative electrode tabs 13a is attached to the upper part of a. This negative electrode lead 13b
A negative electrode terminal 8 penetrating the sealing plate 6 is attached to the. With the above configuration, current can be taken out from the positive electrode terminal 7 and the negative electrode terminal 8.

Next, as shown in FIG. 2, the positive electrode 2 includes a positive electrode current collector (current collector) 2a made of, for example, Al foil, and a positive electrode film (electrode) formed on the positive electrode current collector 2a. Membrane) 2b. The positive electrode tab 12a described above is formed to project from one end of the positive electrode current collector 2a. Positive electrode film 2
b is formed into a film by mixing the solid content and the binder. The solid content contains at least the positive electrode active material powder (electrode active material) and the conductive auxiliary material powder.

Similarly, the negative electrode 3 is composed of a negative electrode collector 3a made of Cu foil or the like, and a negative electrode film 3b formed on the negative electrode collector 3a. The above-mentioned negative electrode tab 13a is formed to project at one end of the negative electrode current collector 3a. The negative electrode film 3b is formed, for example, by mixing a negative electrode active material powder such as graphite and a binder such as polyvinylidene fluoride. In addition, a conductive auxiliary material powder such as carbon black may be added to the negative electrode film 3b. And Figure 2
As shown in, the positive electrode layer 2 b and the negative electrode layer 3 b face each other with the separator 4 in between. In FIG. 2, the electrode films 2b and 3b are formed on one surface of each of the current collectors 2a and 3a for the sake of simplification of description. Needless to say, the films may be formed on both surfaces of the electric bodies 2a and 3a.

The positive electrode film 2b is made into a slurry by mixing solids (positive electrode active material powder and conductive auxiliary material powder) and a binder into a dispersion medium, and the slurry is applied to the positive electrode current collector 2a and then heated. It was obtained by drying. The yield value of the slurry at this time is preferably in the range of 1 to 250 Pa. If the yield value is less than 1 Pa, the slurry will flow excessively,
It is not preferable because it is washed out immediately after being applied on the positive electrode current collector 2a. On the other hand, if the yield value exceeds 250 Pa, the fluidity of the slurry deteriorates, and the slurry cannot be applied onto the positive electrode current collector 2a, which is not preferable.

The solid content of the slurry is 40-80.
The range of volume% is preferable, and the range of 60-80 volume% is more preferable. As the positive electrode active material powder contained in the solid content, lithium manganate, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, vanadium oxide, lithium vanadate, etc. can be used.

Further, it is preferable to use, for example, graphite or carbon black as the conductive auxiliary material powder contained in the solid content. Further, as the binder, it is preferable to use polyvinylidene fluoride, polytetrafluoroethylene, polyimide or the like. The volume fraction of the binder in the total amount of the solid content and the binder is preferably about 1 to 10% by volume. Further, as the dispersion medium of the slurry, for example, N-methylpyrrolidone or the like is preferable.

When the method of applying the slurry to the positive electrode current collector 2a to form the positive electrode film 2b is adopted, agglomerates made of solids are produced during the preparation of the slurry, and the agglomerates are directly contained in the positive electrode film 2b. May remain. In this case, if the particle size of the agglomerates is large, irregularities are generated on the surface of the positive electrode electrode film 2b, and the irregularities may penetrate the separator 4 and short-circuit with the negative electrode 3. Therefore, the particle size of the aggregate contained in the positive electrode film 2b is preferably 50% or less of the film thickness of the electrode film 2b. Thereby, the unevenness due to the aggregates is reduced, the flatness of the surface of the positive electrode film 2b is improved, and the short circuit with the negative electrode 3 can be prevented.
In addition, the aggregate itself is reduced, the dispersibility of the solid content in the slurry is improved, and the dispersibility of the solid content of the positive electrode film 2b can be improved.

As the positive electrode current collector 2a, it is preferable to use metal foil, metal net, expanded metal, or the like.
Further, these materials are preferably Al, Ti, stainless steel or the like.

Further, a conductive polymer material such as polyaniline, polypyrrole, polythiophene or polyimidazole may be added to the positive electrode film 2b. Since these conductive polymer materials are electrochemically stable and have excellent electron conductivity, they are effective in reducing the internal resistance of the positive electrode film 2b.

The yield value of the slurry can be adjusted by appropriately changing the solid content concentration, the specific surface area of the positive electrode active material, the specific surface area of the conductive additive, etc. within the above-mentioned range. The details of the adjustment method of the yield value will be described later.

Next, as the separator 4, for example, a porous polymer material film such as polyethylene or polypropylene, a glass fiber, or a non-woven fabric made of various polymer fibers can be used.

As the non-aqueous electrolyte, for example, a mixed solvent of cyclic carbonic acid ester such as ethylene carbonate and butylene carbonate and chain carbonic acid ester such as dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate is mixed with LiPF ₆ , LiBF ₄ , LiA
sF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ S
It is possible to use one or two or more kinds of solutes composed of a lithium salt such as O ₂ ) ₂ N dissolved therein.

A solid electrolyte (non-aqueous electrolyte) can be used instead of the separator and the non-aqueous electrolyte solution. As the solid electrolyte, a lithium ion conductive polymer such as polyethylene oxide containing the above solute, or a gel electrolyte obtained by impregnating the nonaqueous electrolytic solution into a polymer matrix such as polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, etc. Can be used.

Next, a method of manufacturing the secondary battery electrode of this embodiment will be described. The method for manufacturing the secondary battery electrode of the present embodiment is a slurry prepared by mixing the electrode active material, the conductive auxiliary material, the binder, and the dispersion medium, and applying the dispersion medium after applying the slurry to the current collector. A method for manufacturing an electrode for a secondary battery, wherein an electrode film comprising the electrode active material, the conduction aid and the binder is formed on the current collector by removing the electrode active material, and the electrode film is applied to the current collector. It is characterized in that the yield value of the previous slurry is set in the range of 1 to 250 Pa.

First, the preparation of the slurry will be described.
The slurry according to the present invention is prepared by mixing solid components (positive electrode active material powder and conductive auxiliary material powder) and a binder with a dispersion medium. When the solid content is added to the dispersion medium, the positive electrode active material powder and the conductive auxiliary material powder are mixed in advance to form a mixture, and a dispersion medium such as N-methylpyrrolidone is gradually added to and mixed with the mixture. The binder is preferably dissolved or dispersed in the dispersion medium in advance.

The slurry is preferably prepared so that the yield value is in the range of 1 to 250 Pa. The yield value is 1P
If it is less than a, the slurry excessively flows, and the slurry flows out from the positive electrode current collector 2a immediately after being applied on the positive electrode current collector 2a, which is not preferable. On the other hand, if the yield value exceeds 250 Pa, the fluidity of the slurry deteriorates, and the slurry cannot be applied onto the positive electrode current collector 2a, which is not preferable.

When the dispersion medium is added, the slurry is sufficiently stirred until the particle size of the aggregate contained in the slurry becomes 50% or less of the thickness of the electrode film of the positive electrode to be produced. It is preferable to mix them. Thereby, the aggregate itself is reduced, the dispersibility of the solid content in the slurry is improved, and the electrode film having excellent dispersibility of the solid content can be manufactured.
Further, the irregularities due to the aggregates are reduced, and the positive electrode film 2b
The flatness of the surface is improved and a short circuit with the negative electrode 3 can be prevented. The particle size of the aggregate in the slurry can be measured with, for example, a particle gauge.

The stirring time for preparing the slurry is, for example,
When using a planetary mixer, about 30 to 60 minutes is preferable. If the mixing time is too short, the yield value of the slurry may be less than 1 Pa, which is not preferable, and if the mixing time is too long, the yield value may exceed 250 Pa, which is not preferable. Further, the stirring power of the slurry depends on the size of the blade of the planetary mixer, but in the case of a blade having a diameter of about 500 mm, for example, 60 to 120 r
A rotation speed of about pm is preferable. If the rotation speed is slow, the shear stress is too weak and the yield value of the slurry may be less than 1 Pa, which is not preferable, and if the shearing force is too strong, the yield value may exceed 250 Pa, which is not preferable. Furthermore, the temperature at the time of slurry preparation is, for example,
20-30 degreeC is preferable. If the temperature is too low, the yield value of the slurry may be less than 1 Pa, which is not preferable, and if the temperature is too high, the yield value may exceed 250 Pa, which is not preferable.

The solid content (total amount of the electrode active material and the conductive auxiliary material) contained in the slurry is preferably 40 to 80% by volume, more preferably 60 to 80% by volume. If the solid content in the slurry is less than 40% by volume, the yield value of the slurry may be less than 1 Pa, which is not preferable.
If it exceeds 0% by volume, the yield value may exceed 250 Pa, which is not preferable.

When adjusting the slurry, the value of (total surface area of solid particles in slurry) / (volume of slurry) is in the range of 3 × 10 ⁵ to 15 × 10 ⁵ m ^-1. It is preferable to do so. Here, the solid particles in the slurry in the above formula mean the electrode active material and the conductive auxiliary material. Generally, the positive electrode contains a conductive aid such as carbon black, but the negative electrode may not contain it. Therefore, the total surface area of the solid particles in the slurry is the total surface area of the electrode active material and the conductive auxiliary material. Set the value of (total surface area of solid particles in slurry) / (volume of slurry) to 3
The slurry yield value can be set in the range of 1 to 250 Pa by setting the range of × 10 ⁵ to 15 × 10 ⁵ m ^-1 .

Further, it is preferable to use polyvinylidene fluoride, polytetrafluoroethylene, polyimide or the like as the binder. Further, the volume fraction of the binder in the total amount of the solid content and the binder is preferably in the range of 1 to 10% by volume. If the volume fraction of the binder is less than 1% by volume, the yield value of the slurry will be 1
Since it may be less than Pa, it is not preferable, and when the volume fraction of the binder exceeds 10% by volume, the yield value of the slurry may exceed 250 Pa, which is not preferable.

The yield value of the slurry is, as described above, the mixing time at the time of preparing the slurry, the mixing force, the temperature, the solid content concentration,
By appropriately changing the particle size of the positive electrode active material, the particle size of the conductive additive, the binder, etc. within the above-mentioned range, 1 to 250 Pa can be obtained.
The range can be adjusted.

Next, the prepared slurry is applied to the positive electrode current collector 2a by, for example, the doctor blade method. Since the yield value of the slurry is in the range of 1 to 250 Pa, the fluidity of the slurry is too high and the slurry is washed away from the positive electrode current collector 2a immediately after coating, or the fluidity of the slurry is too low and the positive electrode current collector 2a is too low. There is no possibility that the slurry cannot be applied to the.

Next, the dispersion medium in the slurry is distilled off by drying the slurry by heating under normal pressure or under reduced pressure. By distilling off the dispersion medium, the binder that has been dissolved or dispersed in the slurry is deposited, and the solid content is solidified by this binder to form the positive electrode film 2a. Lastly, the positive electrode film 2b is compacted by roller pressing.
In this way, the positive electrode 2 in which the positive electrode film 2b is carried on the positive electrode current collector 2a is obtained.

The present invention is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention. For example, in the present embodiment, the form in which the positive electrode and the negative electrode are alternately laminated has been described, but the present invention is not limited to this, and a form in which the positive electrode and the negative electrode are spirally wound may be adopted. Further, the appearance of the battery is not limited to the rectangular type, but may be a cylindrical type, a coin type, or a sheet type.

[0044]

Example (Experimental Example 1) Average particle size of positive electrode active material 5 μm
m of lithium manganate (LiMn ₂ O ₄ ) and carbon black having an average particle diameter of 0.05 μm, which is a conductive additive, were mixed with a mixer to form a mixture. Next, N-methylpyrrolidone (NMP (dispersion medium)) in which 5% by weight of polyvinylidene fluoride (PVDF) as a binder was dissolved in advance was gradually added to the mixture in the mixer at a speed of 100 rpm at 30 rpm. The slurries of Examples 1 to 4 and Comparative Examples 1 and 2 were prepared by stirring for 1 minute. Table 1 shows the composition of the slurry. The temperature of the slurry at the time of preparation was 30 ° C.

Next, after measuring the yield value of the prepared slurry, the slurry was applied to an aluminum foil (positive electrode current collector) having a thickness of 20 μm by the doctor blade method, and the state of film formation was observed. The film forming conditions were such that the aluminum foil feed rate was 500 mm / min, and the distance between the blade and the aluminum foil was 100 μm. In Table 1, along with the formulation of the slurry,
The yield value of the slurry and the observation result of the film formation state are shown together.

[0046]

[Table 1]

In Example 1, film formation by the doctor blade method was possible, but since the yield value of the slurry was a little low at 1 Pa, the sharpness of the end portion of the electrode was poor and bleeding was likely to occur. Incidentally, Examples 2 and 3 have moderate yield values,
It has excellent sharpness at the end of the electrode and has few irregularities on the electrode surface. Although it was possible to form a film in Example 4 as well, it was found that the yield value of the slurry was too high to perform sufficient leveling, and the unevenness of the electrode surface after drying became clear. Further, as shown in Table 1, in Examples 1 to 4, the solid content concentration is 40 to 80% by volume, and the yield value is 1 to 250.
It is in the range of Pa. In each of Examples 1 to 4, the film formation by applying the slurry is possible. Particularly, in Examples 2 and 3, the solid content concentration is 50 to 70% by volume, but the yield value is 6 to 36 Pa, and the film formation by slurry coating is in a good state. Next, in Comparative Example 1, the yield value is 0.3 Pa for a solid content concentration of 30% by volume.
And the fluidity of the slurry is extremely high. As a result, in Comparative Example 1, the slurry was washed away from the aluminum foil immediately after the application of the slurry. Next, in Comparative Example 2, the yield value is extremely high at 800 Pa with respect to the solid content concentration of 90% by volume, and the fluidity of the slurry is extremely low. As a result, in Comparative Example 2, it was impossible to apply the slurry onto the aluminum foil.

Therefore, the solid content concentration of the slurry is 40 to 8
The range of 0 volume% is preferable, and the range of 50 to 70 volume% is considered to be more preferable.

(Experimental Example 2) A slurry was prepared in the same manner as in Example 2 except that carbon blacks having different surface areas were used. Table 2 shows the total surface area of the solid particles per unit volume of the slurry. Also, the yield value of the slurry and the observation result of the film formation state are shown together. The temperature of the slurry at the time of preparation was 30 ° C.

[0050]

[Table 2]

As shown in Table 2, in Examples 5 to 8, the surface area of the solid particles per unit volume of the slurry was 3 × 10 5.
⁵ to 15 × 10 ⁵ m ⁻¹ , and the yield value of the slurry at this time is in the range of 1 to 250 Pa. Therefore, Example 5
In No. 8, any film can be formed by applying the slurry. Particularly, in Examples 2 and 3, the surface area of the solid particles per unit volume of the slurry was 500,000 to 1.1 million, and the yield value of the slurry was in the range of 6 to 36 Pa. It is in good condition.
Next, in Comparative Example 3, the surface area of the solid particles per unit volume of the slurry is 500,000 to 1,100,000, and the yield value of the slurry is 0.4 Pa. As a result, in Comparative Example 3, the slurry was washed away from the aluminum foil immediately after the application of the slurry. Next, in Comparative Example 4, the surface area of the solid particles per unit volume of the slurry is 240,000, and the yield value of the slurry is 600 Pa. As a result, in Comparative Example 4, the fluidity of the slurry was lost,
It was impossible to apply the slurry onto the aluminum foil.

Therefore, the surface area of the solid particles per unit volume of the slurry is preferably 3 × 10 ⁵ to 15 × 10 ⁵ m ⁻¹ ,
It is considered that the range of 5 × 10 ^{5 to} 11 × 10 ⁵ m ⁻¹ is more preferable.

(Experimental Example 3) A slurry was prepared in the same manner as in Example 2 except that the aggregate size was controlled by changing the mixing time of the slurry. The slurry was dried with a doctor blade to form a film having a thickness of 100 μm. Table 3 shows the average size of the aggregates in the slurry and the ratio of the thickness to the electrode film thickness. The non-defective rate is shown when a battery is manufactured by alternately stacking 100 positive electrodes and 100 negative electrodes. Here, the resistance value between the positive and negative electrodes was measured with a tester, and the non-short-circuited product was regarded as a non-defective product to distinguish the non-defective battery from the non-defective battery. From the viewpoint of battery production, it is necessary that the yield rate of batteries is at least 90% or more.

[0054]

[Table 3]

As shown in Table 3, in Examples 9 to 11,
The aggregate size in the slurry was 50 μm or less, which was 50% or less of the electrode thickness. At this time, the rate of non-defective batteries was 90% or more. Next, in Comparative Example 3, the aggregate size in the slurry was 65 μm or less,
It became 50% or more with respect to the thickness of the electrode. At this time, the rate of non-defective batteries was significantly reduced to 60%.

Therefore, it is considered preferable that the slurry aggregate size is 50% or less with respect to the thickness of the electrode.

[0057]

As described in detail above, according to the secondary battery electrode of the present invention, the yield value, which is one of the indicators of the fluidity of the slurry, is in the range of 1 to 250 Pa, Since the fluidity is maintained at an appropriate level, the slurry does not run off from the current collector immediately after the slurry is applied, and the slurry cannot be applied. Thereby, the secondary battery electrode having an electrode film having a constant film thickness can be formed.

Further, according to the method of manufacturing the secondary battery electrode of the present invention, the yield value showing the fluidity of the slurry is from 1 to 250 P.
Since it is in the range of a and the fluidity of the slurry is maintained in an appropriate range, there is no possibility that the slurry itself will be washed out immediately after the application of the slurry, or the application of the slurry itself will not be disabled. This makes it possible to form an electrode film having a constant film thickness and also improve the yield at the time of manufacturing the electrode.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a secondary battery that is an embodiment of the present invention.

FIG. 2 is a perspective view showing a main part of the secondary battery shown in FIG.

[Explanation of symbols]

1 secondary battery 2 Positive electrode (electrode) 2a Positive electrode current collector (current collector) 2b Positive electrode film (electrode film) 3 Negative electrode 3a Negative electrode current collector 3b Negative electrode film 4 separator 5 battery case 6 sealing plate

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuyuki Adachi             2-47 Shiobara 2-chome, Minami-ku, Fukuoka City, Fukuoka Prefecture             State Electric Power Co., Inc. (72) Inventor Tsutomu Hashimoto             3-5-1, 717-1, Fukahori-cho, Nagasaki-shi, Nagasaki             Hishi Heavy Industries Ltd. Nagasaki Research Center (72) Inventor Hidehiko Tajima             1-1 Satinoura Town, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries             Nagasaki Shipyard Co., Ltd. F term (reference) 5H029 AJ14 AK03 AL07 AM03 AM05                       AM07 DJ08 HJ01 HJ04 HJ10                 5H050 AA19 BA17 CA08 CA09 CB08                       DA10 DA11 GA10 HA01 HA05                       HA10

Claims (6)

[Claims] 1. A slurry obtained by mixing an electrode active material, a conductive auxiliary material, a binder, and a dispersion medium is applied to a current collector, and then the dispersion medium is removed to remove the electrode active material and the dispersion medium. In the method of manufacturing an electrode for a secondary battery, which comprises forming an electrode film made of a conductive auxiliary material and the binder on the current collector, the yield value of the slurry is in the range of 1 to 250 Pa. Manufacturing method of secondary battery electrode. 2. The total volume fraction of the electrode active material and the conductive additive in the slurry is 40 to 80% by volume.
The method for manufacturing an electrode for a secondary battery according to claim 1, wherein 3. (Total surface area of solid particles in slurry)
The value of / (volume of slurry) is 3 × 10 ⁵ to 15 × 10 ⁵ m
^The method for producing an electrode for a secondary battery according to claim 1, wherein the slurry is in the range of ^-1 . 4. The particle size of the aggregate contained in the electrode film is
The method for manufacturing an electrode for a secondary battery according to claim 1, wherein the slurry is mixed until the film thickness of the electrode film becomes 50% or less. 5. An electrode for a secondary battery manufactured by the method for manufacturing an electrode for a secondary battery according to any one of claims 1 to 4. 6. A secondary battery comprising the secondary battery electrode manufactured by the method for manufacturing a secondary battery electrode according to claim 1. Description: