JP2002100360A - Lithium ion battery negative electrode active material fine particle, lithium ion battery negative electrode board and its manufacturing method, electric conductive agent fine particle for lithium ion battery positive electrode mixture, and lithium ion battery positive electrode board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode mixture paste which is excellent in preservation stability while to providing a lithium ion battery which is excellent in a lithium ion battery electrode board manufacturing method which is skipped or simplified a rolling process, capacity, a rate, and low-temperature characteristics. SOLUTION: The lithium ion battery electrode is created by the manufacturing method which is skipped or simplified the rolling process using electric conduction agent fine particles for positive electrodes and negative electrode active material fine particles in which high molecular compound components are carried out chemical covalent bonding on grain surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative electrode active material powder for a lithium ion battery, a negative electrode plate for a lithium ion battery using the same, a method for producing the same, and a conductive agent powder for a lithium ion battery positive electrode mixture and the same. And a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, as electric and electronic devices such as telephones, video cameras, and notebook computers have become smaller and more portable, or as electric vehicles have been put into practical use, they have been used as power sources for these devices. There has been a demand for higher energy density of such batteries. Therefore, research on lithium ion secondary batteries capable of outputting an output of 3 V or more has been actively conducted and has been put to practical use. Conventionally, the electrodes of these lithium ion secondary batteries have been manufactured as follows.

First, a mixture paste is prepared by mixing an active material with a binder resin, a solvent, and, if necessary, a carbon material powder.

As an active material, in the case of a positive electrode, LiMO ₂
(Where M is a transition metal such as Co, Ni, Al, Mn, Ti, and Fe alone or in combination of two or more), lithium having a spinel structure such as LiMn ₂ O ₄ or the like. When the powder of the composite oxide or the like is a negative electrode, a carbon material powder such as graphite or amorphous carbon is used.

As the binder resin, for example, in the case of a positive electrode, a crystalline fluororesin such as PVDF (polyvinylidene fluoride) or polytetrafluoroethylene, in the case of a negative electrode, an SBR (styrene-butadiene rubber) resin, an olefinic ionomer Resin or the like is used. In addition, a thickener such as carboxymethyl cellulose may be used.

[0006] The mixture paste thus prepared is applied on a current collector and dried to form a sheet-like mixture layer. The current collector may be any material that is electrochemically stable within a range that allows an electrode reaction. Generally, an aluminum foil is used for a positive electrode, and a copper foil is used for a negative electrode.

[0007]

However, in the above-mentioned conventional method for producing a lithium ion battery electrode, the active material concentration in the paste is limited due to the limitation of the dispersibility of the active material in the mixture paste. As a result, the active material weight per unit volume in the electrode plate active material layer after coating and drying was not sufficient.

Therefore, it is necessary to further perform a rolling process such as a roll press to densify the mixture layer, increase the filling ratio of the active material powder, and obtain an electrode plate. In addition, due to the limitation of dispersibility of the active material in the paste, the storage stability of the paste tends to be poor (active material powder is separated and settled in the paste), which is a problem in the production process. Was.

The mixture layer of the electrode thus obtained has fine voids, and in the battery, the electrolyte penetrates into the mixture layer through these voids, so that the electric material of the active material is reduced. The chemical reaction proceeds, and functions as a battery. However, as the conditions of the above-mentioned rolling process become severe,
The opening of the gap in the surface layer of the electrode plate mixture layer is closed, and the penetration of the electrolyte into the electrode mixture in the battery tends to be suppressed, resulting in restrictions on battery characteristics (battery capacity). Was. In particular, under low-temperature atmosphere conditions and rapid discharge conditions, the effect of the electrolyte activity on the capacity was large, and the subject was also great.

Particularly, in the case of the positive electrode, in most cases, a crystalline resin having poor mechanical deformability is used as the binder resin, and the rolling treatment conditions tend to be stricter in each step than in the case of the negative electrode. However, the above-mentioned problem has also become larger.

[0011] Also, comparing the ease of elongation in the direction of the electrode plate surface during rolling, the mixture layer containing the resin component is larger than the current collector of the metal foil. Internal stress is generated between the mixture layers. In the case of a positive electrode in which a crystalline fluorine-based resin is used as the binder resin, the magnitude of the internal stress increases because the stress relaxation effect by the resin component is small.

On the other hand, when the charge and discharge of the battery is repeated, the expansion and contraction of the electrode mixture layer is repeated, and the mixture layer portion is mechanically fatigued, and the electrode mixture layer of the electrode is separated from the core material. However, in the case of a positive electrode having a large internal stress in the electrode plate, once the mixture layer peels off, the peeling proceeds at an accelerated rate, and the battery discharge capacity deteriorates.

The present invention solves the above-mentioned problems, and a method for manufacturing a lithium ion battery electrode plate in which a rolling step is omitted or simplified by chemically bonding a polymer component to the surface of an active material or conductive agent particles. Another object of the present invention is to provide a lithium ion battery having excellent battery characteristics (capacity characteristics, low-temperature characteristics, rate characteristics, and cycle characteristics) and to realize an electrode mixture paste having excellent storage stability.

[0014]

Means for Solving the Problems To solve the above problems, a lithium ion battery negative electrode active material powder of the present invention is composed of a polymer compound component and an active material particle component, wherein the polymer compound component is an active material. It is characterized by being chemically covalently bonded to the surface of the substance particle component.

In the negative electrode active material powder for a lithium ion battery having the above structure, it is preferable that the polymer compound component is in the range of 0.4 to 0.8 parts by weight based on 100 parts by weight of the active material particle component.

Further, in the lithium ion battery negative electrode active material powder having the above structure, it is preferable that the polymer compound component is made of at least one of a polyethylene oxide polymer and a polypropylene oxide polymer.

A negative electrode plate for a lithium ion battery according to the present invention is characterized by containing the negative electrode active material powder for a lithium ion battery according to the present invention.

Further, in the method for producing a negative electrode plate of a lithium ion battery according to the present invention, the powder of the negative electrode active material of the lithium ion battery according to the present invention is formed into a paste using a solvent, and the paste is coated on a current collector and dried. And the rolling process is not performed.

The conductive powder for a positive electrode mixture of a lithium ion battery according to the present invention is composed of a polymer compound component and a conductive particle component, and the polymer compound component is chemically shared on the surface of the conductive particle component. It is characterized by being connected.

In the conductive powder for a positive electrode mixture of a lithium ion battery of the present invention, the polymer compound component is in the range of 0.3 to 0.8 parts by weight based on 100 parts by weight of the conductive particle component. Is preferred.

Further, a positive electrode plate of a lithium ion battery of the present invention is characterized by containing the above-mentioned conductive agent powder for a positive electrode mixture of a lithium ion battery of the present invention.

The method for producing a positive electrode plate of a lithium ion battery of the present invention comprises the steps of: forming a conductive agent powder comprising the conductive agent powder for a lithium ion battery positive electrode mixture of the present invention; And applying the paste on a current collector.
It is characterized by being dried and not subjected to a rolling process.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The negative electrode active material powder of a lithium ion battery of the present invention comprises a polymer compound component and an active material particle component, and the polymer compound component is chemically shared on the surface of the active material particle component. It is characterized by being connected.

This polymer compound component has a good affinity for the solvent component and the binder resin component used in the paste, so that it can be compared with a conventional example using an active material powder having no polymer compound bonded to the surface. The dispersibility of the powder in the paste is improved.

Further, since the polymer compound component is firmly bonded to the surface of the active material particle component by a chemical covalent bond, the polymer compound component and the active material particle component are separated at the time of pasting, The effect of improving the dispersibility is not lost.

Therefore, by using the negative electrode active material powder of the lithium ion battery of the present invention, it becomes possible to mix a large amount of the active material into the paste.
Since the active material weight per unit volume of the active material mixture layer after application and drying can be increased, the electrode plate rolling process conventionally performed after application and drying can be omitted or the conditions can be reduced. It becomes possible.

Further, by improving the dispersibility of the active material in the paste, it is possible to suppress sedimentation and aggregation of the active material, and to obtain an electrode paste having excellent storage stability. Further, with respect to the negative electrode active material powder for a lithium ion battery having the above-described structure, with respect to 100 parts by weight of active material component
It is preferable that the amount of the polymer compound component is in the range of 0.4 to 0.8 parts by weight.

When the ratio of the high molecular compound component is small,
The effect of improving the dispersibility of the active material described above may be insufficient, so that an electrode plate rolling process may be required or the rolling conditions may be severe. When the ratio of the polymer compound component is large, the ion and electron conductivity to the active material component are limited due to the active material layer coating with the polymer compound component, and as a result, the battery capacity,
Rate and low-temperature characteristics may deteriorate.

In the negative electrode active material powder for a lithium ion battery having the above structure, the polymer compound component is preferably composed of at least one of a polyethylene oxide polymer and a polypropylene oxide polymer. Since the components have lithium ion conductivity in the battery, they contribute to the electrochemical reaction of the negative electrode active material, and as a result, battery characteristics (capacity, rate, low-temperature characteristics) are improved.

The conductive agent powder for a lithium ion battery positive electrode mixture of the present invention is composed of a polymer compound component and a conductive particle component, and the polymer compound component is chemically covalently bonded to the surface of the conductive particle component. It is characterized by having.

This polymer compound component has a good affinity for the solvent component and the binder resin component used in the mixture paste, so that it is different from the conventional example using a conductive agent powder having no polymer compound bonded to the surface. By comparison, the dispersibility of the powder in the paste is improved. Further, since the polymer compound component is firmly bonded to the surface of the conductive particle component by a chemical covalent bond, the polymer compound component and the conductive particle component are separated during the paste formation, and the dispersibility is reduced. The effect of the improvement is not lost.

Since the dispersibility of the positive electrode mixture paste is generally governed by the dispersibility of the conductive agent, a large amount of the conductive agent and active material can be obtained by using the conductive agent powder for a lithium ion battery positive electrode mixture of the present invention. Can be incorporated into the paste. As a result, the active material weight per unit volume of the active material mixture layer after application and drying can be increased, and the conductive agent weight can be increased. It is possible to omit or relax the conditions.

Further, by improving the dispersibility of the active material in the paste, it is possible to suppress the sedimentation and aggregation of the active material and the conductive agent, and to obtain an electrode paste having excellent storage stability. Further, with respect to the conductive agent powder for a lithium ion battery positive electrode mixture having the above configuration, the polymer compound component is preferably in the range of 0.3 to 0.8 part by weight with respect to 100 parts by weight of the active material component. .

When the ratio of the high molecular compound components is small,
The effect of improving the dispersibility of the paste described above becomes insufficient, so that an electrode plate rolling treatment step may be required, or the rolling conditions may become severe. When the ratio of the polymer compound component is large, the electronic conductivity of the electrode plate is limited due to the coating of the conductive agent with the polymer compound component, and as a result, the battery capacity, rate, and low-temperature characteristics may be deteriorated.

The polymer compound component of the negative electrode active material powder in the present invention includes, for example, polyethylene oxide polymer, polypropylene oxide polymer, polyacrylamide polymer, carboxymethyl cellulose polymer and the like. .

Examples of the active material particle component of the negative electrode active material powder of the present invention include carbon materials such as graphite and amorphous carbon.

In the method for producing a negative electrode plate and a positive electrode plate of a lithium ion battery of the present invention, for example,
Water, N-methyl-2-pyrrolidone, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone and the like are used, and they are used alone or as a mixed solvent.

In the method for producing a negative electrode plate of a lithium ion battery of the present invention, the paste may contain other components such as a binder resin and a thickener, in addition to the solvent and the active material powder. .

As the current collector of the present invention, any material may be used as long as it is electrochemically stable within a range that allows an electrode reaction. For example, an aluminum foil for a positive electrode and a copper foil for a negative electrode may be used. Can be

The coating method of the present invention is not particularly limited, and examples thereof include a die coating method and a comma coating method.

The drying method of the present invention is not particularly limited, and examples thereof include a hot air drying method and a far infrared ray irradiation method.

The polymer component of the positive electrode conductive agent powder for a lithium ion battery of the present invention includes, for example, a polymer component such as a vinylidene fluoride polymer or a vinylidene fluoride-maleic acid copolymer.

Examples of the conductive particle component of the present invention include carbon material components such as acetylene black and furnace black.

As the positive electrode active material of the present invention, LiMO ₂
(Where M is a transition metal such as Co, Ni, Al, Mn, Ti, and Fe alone or in combination of two or more), lithium having a spinel structure such as LiMn ₂ O ₄ or the like. Composite oxides and the like can be mentioned.

In the method for producing a positive electrode plate of a lithium ion battery of the present invention, the paste contains other components such as a binder resin and a thickener in addition to the solvent, the conductive agent and the positive electrode active material. Is also good.

Hereinafter, the present invention will be described more specifically with reference to examples.

[0047]

Example 1 A graphite-based negative electrode active material mesocarbon microbeads (manufactured by Kawasaki Steel Co., Ltd.) having a center particle size of 5 μm was treated with 60% nitric acid at a temperature of 100 ° C. for 1 minute to form a surface. The aromatic ring was oxidized to introduce a carboxyl group. The amount of surface carboxyl groups calculated from the acid value of the powder after the treatment was 0.002 mmol per 1 g of the powder.
Met.

This powder was treated with SOCl ₂ to convert the carboxyl group into an acid chloride group, and further treated with hydroxyazobenzene to convert the acid chloride group into an azo group. By polymerizing 300 g of the obtained powder with 10 kg of N-vinyl-2-pyrrolidone at a temperature of 70 ° C., a powder having a polyvinylpyrrolidone component bonded to mesocarbon microbeads by phenylene bond was obtained. . When the number average molecular weight and the introduced amount of the polyvinylpyrrolidone component were evaluated by elemental analysis, the number average molecular weight was 8000 and the introduced amount was 0.5 part by weight with respect to 100 parts by weight of the mesocarbon microbead component.

Next, graphite-based negative electrode active material mesocarbon microbeads (manufactured by Kawasaki Steel) having a center particle size of 5 μm were heated at a temperature of 1 ° C.
By treating with 60% nitric acid at 00 ° C for 1 minute,
The aromatic ring on the surface was oxidized to introduce a carboxyl group. The amount of surface carboxyl groups of the powder after the treatment, calculated from the acid value measurement, was 0.002 mmol per 1 g of the powder.

This powder was treated with SOCl ₂ to convert a carboxyl group into an acid chloride group.
By treating with ₃ , the acid chloride group was converted to an acyl azide group. 250 g of the obtained powder was mixed with 15 kg of polyvinyl alcohol (number average molecular weight: 22000) and
with dimethylsulfoxide solvent at a temperature of 130
By reacting at 20 ° C. for 20 hours, a powder was obtained in which the polyvinyl alcohol component was bonded on the mesocarbon microbeads by urethane bonds. When the introduction amount of the polyvinyl alcohol component was evaluated by elemental analysis, based on 100 parts by weight of the mesocarbon microbead component,
0.8 parts by weight.

The treatment time of the nitric acid treatment of the active material is set at 10
The same experiment was carried out for 3 seconds and 3 minutes, and the amount of the polyvinyl alcohol component introduced was changed to the mesocarbon microbead component 1
Samples were also prepared with 0.1 parts by weight and 2 parts by weight based on 00 parts by weight. Similarly, polyethylene glycol (number average molecular weight: 6000) was mixed with
The graphite-based negative electrode active material of μm was bonded to the surface of mesocarbon microbeads (made by Kawasaki Steel). At this time, the treatment of the mesocarbon microbeads with 60% nitric acid is performed at a temperature of 10%.
Performed at 0 ° C. for 5 minutes to determine the amount of surface carboxyl groups.
0.005 mmol per 1 g of powder. No solvent was used during the introduction reaction of the polyethylene glycol component.

When the introduced amount of the polyethylene glycol component in the obtained powder was evaluated by elemental analysis, it was 0.6 parts by weight with respect to 100 parts by weight of the mesocarbon microbead component. Similarly, polypropylene glycol (number average molecular weight: 2000) was bonded to the surface of graphite-based negative electrode active material mesocarbon microbeads (manufactured by Kawasaki Steel) having a center particle size of 5 μm. At this time, the treatment of the mesocarbon microbeads with 60% nitric acid is performed at a temperature of 100 ° C.
Perform for 20 minutes, and determine the amount of surface carboxyl groups by 1 g of powder.
0.02 mmol per unit. No solvent was used during the introduction reaction of the polyethylene glycol component.

The amount of the introduced polypropylene glycol component in the obtained powder was evaluated by elemental analysis.
Parts by weight.

(Example 2) The experiment of Example 1 was repeated.
Each of the active material powders having the polymer component bonded thereto was prepared in a large amount. Each of the active material powders is a VG of carbon material.
After mixing with 50 g of CF powder, an aqueous solution of carboxymethyl cellulose resin (Cellogen 4H manufactured by Daiichi Kogyo Seiyaku) (concentration 1
%) And kneaded for 30 minutes. As a kneading machine, Hibis Dispermix (volume: 5 L) manufactured by Tokushu Kika Co., Ltd. was used, and kneading was performed by a planetary mixer. The blade rotation speed at that time was 50 rpm.
At this time, the paste solid content concentration was 50.5%, and the ratio of VGCF and resin component (carboxymethyl cellulose resin and high molecular compound component bonded to the active material surface) to 95 parts of active material mesocarbon microbeads. Are 5 parts and 1 part, respectively.

Thereafter, an aqueous dispersion of styrene-butadiene rubber and dilution water were further added, and the mixture was used for 10 minutes by using both functions of a planetary mixer (a blade rotation speed: 50 rpm) and a disper (a rotation speed: 2500 rpm) of a kneader. Dilution mixing was performed to dilute and complete the paste. The solid content of styrene-butadiene rubber in the final paste was 2 parts per 95 parts of mesocarbon microbeads.
Parts, and the solid content concentration of the entire paste is 50%
It is.

Regarding the obtained paste sample, the polymer component of the active material was a polyvinylpyrrolidone component, and the polyvinyl alcohol component was introduced in an amount of 100 active materials.
0.8 parts by weight, 0.1 parts by weight, 2.0 parts by weight, polyethylene glycol component, and polypropylene glycol component with respect to parts by weight, respectively. M1, M2, M
3, M4, M5, and M6.

(Comparative Example 1) 950 g of mesocarbon microbead powder (manufactured by Kawasaki Iron & Steel Co., Ltd.) having a center particle diameter of 5 μm was mixed with 50 g of VGCF powder of a carbon material, and then an aqueous solution of a carboxymethyl cellulose resin (Daiichi Kogyo Seiyaku 4H) was used. 1000 g (concentration 1%) was added and kneaded for 30 minutes. As a kneading machine, Hibis Dispermix (volume: 5 L) manufactured by Tokushu Kika Co., Ltd. was used, and kneading was performed by a planetary mixer. The blade rotation speed at that time is 50 rpm
And At this point, the paste solids concentration is 50.5
%, VGCF based on 95 parts of active material mesocarbon microbeads, resin component (polymer compound component bonded to carboxymethylcellulose resin and active material surface)
Are 5 parts and 1 part, respectively.

Thereafter, an aqueous dispersion of styrene-butadiene rubber and dilution water are further added, and the mixture is used for 10 minutes by using both functions of a planetary mixer (blade rotation speed: 50 rpm) and a disper (rotation speed: 2500 rpm) of a kneader. Dilution mixing was performed to dilute and complete the paste. The solid content of styrene-butadiene rubber in the final paste was 2 parts per 95 parts of mesocarbon microbeads.
Parts, and the solid content concentration of the entire paste is 50%
It is.

The obtained paste was designated as paste M0.

Example 3 The viscosities of the pastes obtained in the above Examples and Comparative Examples were evaluated using a rheometer (RFSII manufactured by Rheometrics). Shear rate 10 s ^-1
Are shown in (Table 1).

Regarding the storage stability of the paste,
Each paste immediately after preparation was put into a cylindrical (diameter: 50 mm) glass container at a depth of 120 mm, and evaluated by the ratio (volume ratio) of the supernatant portion to the total amount of the paste generated after standing for 48 hours in a 25 ° C. atmosphere. Carried out. The results are shown in (Table 1). Further, each paste was applied on a copper foil having a thickness of 14 μm by a comma coating method and dried, and films were formed on both sides of the foil to form an electrode plate. Table 1 shows the one-side film thickness and the weight of the active material per unit volume of the obtained mixture film.

[0062]

[Table 1]

From Table 1, the viscosity values of the pastes M1 to M6 in which the polymer compound components are chemically covalently bonded to the surface of the active material particles are respectively different from those of the corresponding paste M0 of the related art. Also, it was confirmed that the value of the supernatant ratio after the 48th standing was reduced, and it is considered that the dispersibility of the active material in the paste and the storage stability of the paste were improved.

Also, it can be confirmed that the weight of the active material per unit volume of the mixture layer is higher in the case of the pastes M1 to M6 than in the case of the paste M0.

However, the amount of the high molecular compound chemically covalently bonded to the surface of the active material particles is small (the active material particle component 10
(0.1 parts by weight with respect to 0 parts by weight) In the case of paste M3, all of active material dispersibility, storage stability, and mixture active material weight are improved as compared with pastes M1, M2, M4 to M6. The effect is less.

Example 4 Carbon powder acetylene black (DENKA BLACK manufactured by Denki Kagaku Kogyo Co., Ltd.) was heated to a temperature of 100 ° C.
By treating with 60% nitric acid for 1 minute, the aromatic ring on the surface was oxidized to introduce a carboxyl group. The amount of surface carboxyl groups of the powder after the treatment, calculated from the acid value measurement, was 0.002 mmol per 1 g of the powder.
This powder was treated with SOCl ₂ to convert the carboxyl group to an acid chloride group, and further treated with hydroxyazobenzene to convert the acid chloride group to an azo group. 300 g of the obtained powder is mixed with vinylidene fluoride 1
By polymerizing at 0 kg and at a temperature of 100 ° C.,
A powder in which the polyvinylidene fluoride component was bonded on acetylene black by phenylene bond was obtained.

When the number average molecular weight and the introduced amount of the polyvinylidene fluoride component were evaluated by elemental analysis, the number average molecular weight was 8,000 and the introduced amount was 10%.
It was 0.6 parts by weight with respect to 0 parts by weight.

The treatment time of the nitric acid treatment of the active material is set to 10
The same experiment was performed for 3 seconds and 3 minutes, and samples were prepared in which the amount of the polyvinyl alcohol component introduced was 0.1 part by weight and 1 part by weight based on 100 parts by weight of the acetylene black component.

Example 5 Using the acetylene black powder prepared in Example 4 as a conductive agent, a positive electrode paste was prepared as follows. The obtained conductive agent was mixed with 2000 g of lithium cobalt oxide powder (manufactured by Matsushita Battery) having a center particle diameter of 7 μm of the positive electrode active material, and then a solution of polyvinylidene fluoride resin in N-methyl-2-pyrrolidone (concentration: 12%, Kureha) KF1320 manufactured by Chemical Industry, N-methyl-2-pyrrolidone solvent is added, the solid content concentration is 78%, a conductive agent for 100 parts of the active material in the paste, a polyvinylidene fluoride resin (including those bonded to the surface of the conductive agent. ) Were 3 parts and 3 parts, respectively. For this mixture, 30
Kneading was performed for a minute. As a kneading machine, Hibis Dispermix (volume: 5 L) manufactured by Tokushu Kika Co., Ltd. was used, and kneading was performed by a planetary mixer. The blade rotation speed at that time was 50 rpm.

Thereafter, an N-methyl-2-pyrrolidone solvent was further added, and a planetary mixer (blade rotation speed: 50 rpm) and a disper (rotation speed: 250 rpm) of a kneader were added.
(0 rpm), the paste was diluted to a final paste solids concentration of 70%.

Regarding the obtained paste samples, those in which the amount of the polymer component of the conductive agent introduced was 0.6 parts by weight and 0.1 parts by weight with respect to 100 parts by weight of the conductive particle component. What was 0 parts by weight was defined as pastes P1, P2, and P3, respectively.

(Comparative Example 2) 2000 g of lithium cobalt oxide powder (manufactured by Matsushita Battery) having a center particle size of 7 μm was mixed with acetylene black powder (Denka Black manufactured by Denki Kagaku Kogyo) 6
After mixing with 0 g, an N-methyl-2-pyrrolidone solution of polyvinylidene fluoride resin (concentration 12%, K
F1320), and kneaded for 30 minutes. As a kneading machine, Hibis Dispermix (volume: 5 L) manufactured by Tokushu Kika Co., Ltd. was used, and kneading was performed by a planetary mixer. The blade rotation speed at that time was 50 rpm. At this time, the paste solids concentration was 78%, and the ratios of acetylene black and polyvinylidene fluoride resin to 100 parts of the active material in the paste were:
Three parts and three parts.

Thereafter, an N-methyl-2-pyrrolidone solvent was further added, and a planetary mixer (blade rotation speed: 50 rpm) and a disper (rotation speed: 250 rpm) of a kneader were added.
(0 rpm), the paste was diluted to prepare a positive electrode paste having a solid concentration of 70%. The obtained paste was designated as paste P0.

Example 6 The viscosities of the pastes obtained in Example 5 and Comparative Example 2 were evaluated using a rheometer (RFSII manufactured by Rheometrics). Shear rate 10 s ^-1
Are shown in (Table 2).

Further, each paste was applied on an aluminum foil having a thickness of 20 μm by a comma coating method and dried, and films were formed on both sides of the foil to obtain an electrode plate. The thickness of the single-sided film and the weight of the active material per unit volume of the obtained mixture film are shown in Table 2.
Shown in

[0076]

[Table 2]

From Table 2, it can be seen that the pastes P1 to P3 in which the polymer component is chemically covalently bonded to the surface of the conductive agent particles have a higher viscosity than the corresponding conventional paste P0. You can see that the value has decreased,
It is considered that the dispersibility of the powder in the paste has been improved.

Also, it can be confirmed that the weight of the active material per unit volume of the mixture layer is higher in the case of the pastes P1 to P3 than in the case of the paste P0. However, in the case of the paste P2 in which the amount of the polymer compound chemically covalently bonded to the surface of the active material particles is small (0.1 part by weight with respect to 100 parts by weight of the active material particle component), the active material dispersibility and the mixture Regarding any active material weight, paste P
1 and P3, the improvement effect is smaller.

(Example 7) A battery using the above-mentioned electrode plate was constructed in the following procedure. Pastes M0, M1, M3, P0,
As for the electrode plate obtained from P2, the active material weight per unit volume of the mixture layer was not sufficient. Therefore, first, roll rolling was performed, and the filling rate was determined. The negative electrode was 1.3 g / c.
m ³ , and 3.0 g / cm ³ for the positive electrode. As a rolling mill, M-17000 manufactured by Yuri Roll Co., Ltd. was used. The obtained electrode plates were referred to as electrode plates M0, M1, M3, P0, and P2. The number of times of rolling is shown in (Table 1) and (Table 2). Negative electrode plate and positive electrode plate of the present invention (electrode plates M1, M3, P2)
Is smaller in the number of rolling times than the conventional example (electrode plates M0, P0).

Other pastes M2, M4-6, P1, P3
The electrode plate obtained by using was able to be used without rolling because the active material weight per unit volume in the mixture was sufficiently large. Electrode plates M2, M4-6, P
1, P3.

These electrode plates were used for the positive electrode and had a length of 3
80 mm, width 37 mm, length 420 for the negative electrode
mm and a width of 39 mm, and the obtained positive electrode plate and negative electrode plate are overlapped with each other via a polyethylene separator having a thickness of 25 μm, a width of 45 mm, and a length of 1000 mm, and spirally wound in the length direction to form an electrode plate. They were grouped and stored in a battery case having a diameter of 17 mm and a height of 50 mm.

Then, ethylene carbonate was placed in the battery case.
And ethyl methyl carbonate in a volume ratio of 20:80.
1 mol / L Li as an electrolyte in the solvent mixed with
PF ₆After injecting the dissolved electrolyte, open the case
The battery case is sealed by fitting the sealing plate to
I got a battery.

These batteries were charged and discharged in an atmosphere of 25 ° C. and 0 ° C., and their discharge capacities were evaluated. Charging is
The operation was performed at a constant current of 1000 mA to 4.1 V, and the discharge conditions were 200 mA and a final voltage of 2.75 V. The same evaluation was performed under the condition of a discharge current of 1000 mA (at 25 ° C.).

For each combination of the positive and negative electrode plates, the results at a discharge current of 200 mA, an ambient temperature of 25 ° C. and 0 ° C. are shown in Tables 3 and 4, respectively.
The results at 0 mA and an ambient temperature of 25 ° C. are shown in (Table 5).

The charge and discharge conditions (discharge current 200 m
(A, ambient temperature 25 ° C.), the charge / discharge was repeated 500 times, and the discharge capacity was also evaluated. The results are shown in (Table 6).

All the results are shown as relative values when the value of the combination of the electrode plates M0 and P0 is 100 at an ambient temperature of 25 ° C. and a discharge current of 200 mA.

[0087]

[Table 3]

[0088]

[Table 4]

[0089]

[Table 5]

[0090]

[Table 6]

From all the results, it can be seen that the discharge capacity of the battery using the electrode plate according to the present invention is superior or equal to that of the battery using the conventional electrode plate. In particular, low-temperature atmosphere conditions, rapid discharge conditions,
Regarding the capacity under the condition of repeating 00 times, the battery using the electrode plate according to the present invention was much better than the battery using the conventional electrode plate.

Further, when the negative electrode active material powder of the present invention in which the polymer compound component is a polyethylene glycol (polyethylene oxide polymer) component or a polypropylene glycol (polypropylene oxide polymer) component is used (electrode M5, M6), or the polymer component is 0.4 to 100 parts by weight of the active material particle component.
When the negative electrode active material powder of the present invention in the range of 0.8 parts by weight is used (when the electrodes M1, M2, M5, and M6 are used), the polymer component is added to 100 parts by weight of the conductive particle component. Is in the range of 0.3 to 0.8 parts by weight when the conductive agent powder for a positive electrode mixture of the present invention is used (when the electrode P1 is used).
It was also recognized that the above-mentioned improvement effect was particularly large.

[0093]

As described above, the present invention provides a method for manufacturing a lithium ion battery electrode plate in which the rolling step is omitted or simplified by chemically bonding the polymer component to the surface of the active material or the conductive agent particles, It is possible to provide a lithium-ion battery having excellent low-temperature, low-temperature characteristics, and to realize an electrode mixture paste having excellent storage stability.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) // H01M 10/40 H01M 10/40 Z F term (reference) 5H029 AJ02 AJ03 AJ04 AK03 AL07 AL08 AM03 AM05 AM07 CJ02 CJ08 CJ22 DJ08 DJ16 EJ13 HJ01 5H050 AA02 AA06 AA08 AA09 BA17 CA07 CA08 CA09 CB08 CB09 DA09 DA10 DA18 EA23 FA17 GA02 GA10 GA22 HA01

Claims (9)

[Claims] 1. A lithium ion battery negative electrode active material powder comprising a polymer compound component and an active material particle component, wherein the polymer compound component is chemically covalently bonded to a surface of the active material particle component. body. 2. 100 parts by weight of the active material particle component,
The negative electrode active material powder for a lithium ion battery according to claim 1, wherein the amount of the polymer compound component is in the range of 0.4 to 0.8 parts by weight. 3. The lithium ion battery negative electrode active material powder according to claim 1, wherein the polymer compound component comprises at least one of a polyethylene oxide polymer and a polypropylene oxide polymer. 4. A negative electrode plate for a lithium ion battery, comprising the negative electrode active material powder for a lithium ion battery according to claim 1. 5. A paste of the negative electrode active material powder for a lithium ion battery according to claim 1 using a solvent, and applying and drying the paste on a current collector, followed by rolling. A method for producing a negative electrode plate for a lithium ion battery, comprising the steps of: 6. A positive electrode mixture for a lithium ion battery, comprising a polymer compound component and a conductive particle component, wherein the polymer compound component is chemically covalently bonded to a surface of the conductive particle component. Conductive agent powder. 7. The conductive particle component, relative to 100 parts by weight,
The conductive agent powder for a lithium ion battery positive electrode mixture according to claim 6, wherein the polymer compound component is in a range of 0.3 to 0.8 parts by weight. 8. A positive electrode plate for a lithium ion battery, comprising the conductive agent powder for a positive electrode mixture for a lithium ion battery according to claim 6 or 7. 9. A paste comprising: a conductive agent powder comprising the conductive agent powder for a lithium ion battery positive electrode mixture according to claim 6 or 7; and a positive electrode active material, wherein the paste is formed by using a solvent, and the paste is used as a current collector. A method for producing a positive electrode plate for a lithium ion battery, wherein the positive electrode plate is coated and dried, and is not rolled.