JP2003217573A - Slurry for forming negative electrode film of non- aqueous secondary battery and control method of slurry - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous slurry for a negative electrode film of a non- aqueous secondary battery that is superior in handling safety and superior in adhesion between the current collector and the crystalline or flake graphite material as well as the synthetic carbon material such as refractory graphic carbon and mesophase carbon microbeads, and that has little degradation of the discharge capacity, and is superior in durability for charge and discharge cycle, and a control method of the slurry. <P>SOLUTION: This is a slurry of a basic structure in which the solid portion is a carbon material active substance and a binder and the medium is water, and the viscosity property of the slurry is γ=10<SP>κ</SP>×τ<SP>n</SP>in the relationship of the shear rate (γ s<SP>-1</SP>) and the shearing stress (τ Pa), wherein, κ is in the range -1.0--9.0 and n is 1.1-4.5. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aqueous slurry for forming a negative electrode coating film suitable for a non-aqueous secondary battery and a method for adjusting the viscosity characteristics of the slurry.

[0002]

2. Description of the Related Art As negative electrode active materials for lithium-ion secondary batteries, carbon materials such as mesophase carbon microbeads (MCMB) and non-graphitizable carbon are mainly used. Further, a fluorine-based resin typified by polyvinylidene fluoride (PVDF) resin is mainly used as the binder, and these resins are used as an organic solvent such as N-methyl-2-pyrrolidone (NMP) together with the negative electrode active material. By kneading and forming a slurry, a slurry for forming a negative electrode coating film of a lithium ion secondary battery is obtained. Lithium ion secondary batteries are widely used as rechargeable power sources for notebook computers, mobile phones, etc., but there is a demand for higher capacity and higher voltage batteries to further expand the range of use. In order to meet the demands for high capacity and high voltage of such a battery, it is essential to increase the capacity of the negative electrode material and enhance the potential stability, and it is necessary to consider using a graphite material as the negative electrode active material. It is being advanced. This is because the graphite material forms a theoretical lithium-graphite intercalation compound because the crystallinity is high, and a value close to the theoretical charge / discharge capacity of 372 mAh / g can be obtained, and the potential stability is also high. Because it is expensive.

However, since the crystal structure of the graphite material has a high cohesive force in the layer direction, pulverization produces a flaky or phosphorus-like flaky particle powder. Therefore, a binder made of a fluorine-based resin typified by PVDF, which has been mainly used in the past, has a low film-forming property, and sufficient adhesion between graphite particles and a copper foil as a current collector cannot be obtained. . As a result, even if graphite powder, which is advantageous in terms of crystal structure, is used as the negative electrode active material, the charge and discharge capacity is reduced due to its high electric resistance value, and the capacity is greatly reduced at large current. Further, there is a drawback that the capacity is greatly reduced in a charge / discharge cycle in which charge / discharge is repeated. Further, it is pointed out that the fluorine-based resin decomposes at a high temperature, and the released fluorine and lithium react violently as a safety problem. Further, when using a fluorine-based resin represented by PVDF as a binder, an organic solvent such as NMP is used as a solvent for slurrying, but in recent years consideration for the environment and safety of workers and From the viewpoint of price and the like, it is preferable to make the solvent for slurrying aqueous. Of course, even as an aqueous slurry, a negative electrode coating film having the same or some performance as that of a coating film obtained from a conventional solvent-based slurry, such as relaxing the adhesion of the obtained coating film and swelling / shrinkage during charging / discharging. And have to. As a slurry or a negative electrode coating film for forming a negative electrode coating film of a non-aqueous secondary battery having a water-based emulsion resin, a water-based binder as a thickening agent, and a carbonaceous active material as a basic structure, for example, JP-A-4-342966. Discloses a slurry having a specified ratio of carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR). Further, JP-A-8-250122 discloses a negative electrode composed of a styrene-butadiene latex having a specified butadiene content and a carbonaceous active material.

[0004]

SUMMARY OF THE INVENTION The present invention provides the above-mentioned object, namely, to provide an aqueous slurry excellent in handling safety, and to obtain a synthetic carbon material such as non-graphitizable carbon or MCMB, or a phosphorus-like or phosphorus-containing material. Slurry for forming a negative electrode coating film of a non-aqueous secondary battery, which has excellent adhesion between a flake graphite material and a current collector, has little decrease in discharge capacity, and has excellent durability against charge / discharge cycles, and a method for adjusting this slurry Is provided.

[0005]

In order to solve the above-mentioned problems, the slurry of the present invention is a non-aqueous two-component slurry whose solids are a carbonaceous material active material and a binder and whose medium is water. in negative Gokunuri film forming slurry of the following cell, the viscosity characteristics of the slurry, the shear rate (γ s ^{- 1)} and in relation to the shear stress ^{(τ Pa) γ = 10 κ} × τ n
And κ is in the range of -1.0 to -9.0, and n
Is in the range of 1.1 to 4.5, to provide a slurry for forming a negative electrode coating film of a non-aqueous secondary battery. The binder used in this slurry is composed of a water-dispersed emulsion resin and a water-soluble polymer, and the content of the water-soluble polymer in the binder is in the range of 30 to 65% by mass.
Moreover, the amount of the binder compounded in the solid content of the slurry is 1 to
This water-dispersed emulsion resin has a minimum film-forming temperature of 10 ° C. or less, a natural rubber (NR) latex, a styrene-butadiene rubber (SBR) latex, a butadiene rubber (BR) latex, and an acrylonitrile-butadiene resin. Copolymer rubber (NBR) latex,
Methyl methacrylate / butadiene copolymer rubber (MB
R) is at least one selected from latex, styrene-butadiene-styrene copolymer (SBS) latex and acrylic ester resin emulsion, and the water-soluble polymer has a viscosity of a 1% by mass aqueous solution at 25 ° C. of 200 to 2 , 500 mPa · s, one or more selected from sodium alginate, potassium alginate, ammonium alginate, propylene glycol alginate, carboxymethyl cellulose and its sodium salt or ammonium salt, hydroxyethyl cellulose, polyethylene oxide, polyvinyl alcohol, casein, sodium polyacrylate. And in addition,
The carbon material active material used for this slurry contains 50 mass% or more of the massive graphite particle group composed of phosphorus-like or flake-like natural graphite particles, and the massive graphite particle group is
The cumulative 50% diameter (D50 diameter) in the laser light diffraction method is 10 to 25 μm, the specific surface area in the nitrogen gas adsorption method is 2.5 to ⁵ m ² / g, and the apparent density in the stationary method is 0.4.
5 g / cm ³ or more, apparent density in tap method is 0.
70 g / cm ³ or more. Another invention of the present application is that the viscosity characteristics of a slurry for forming a negative electrode coating film of a non-aqueous secondary battery in which a main constituent material is a carbon material active material, a binder and an aqueous medium are shear rates (γ s ⁻¹ ). And shear stress (τ P
In the relationship with a), γ = 10 ^κ × τ ^n, and κ is −
It is intended to provide a method for adjusting a slurry for forming a negative electrode coating film of a non-aqueous secondary battery in which the range of 1.0 to -9.0 and n is 1.1 to 4.5.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The first feature of the present invention is the formation of a negative electrode coating film for a non-aqueous secondary battery whose solid content is a carbonaceous material active material and a binder and whose medium is water. In the case of the slurry for slurry, the viscosity characteristic of the slurry is
s ⁻¹ ) and the shear stress (τ Pa) as a relation γ = 1
0 ^κ × τ ⁿ , κ in the range of -1.0 to -9.0, and n in the range of 1.1 to 4.5 for forming a negative electrode coating film of a non-aqueous secondary battery. It is a slurry.

Most of polymer coatings and colloidal coatings are usually thixotropic fluids exhibiting thixotropic (pseudoplastic) flow, that is, viscosity decreases when fluidized, but cures again when fluidization stops (viscosity increases). And returns to the original viscosity). In addition to the thixotropic fluid, there are Newtonian fluids whose viscosity does not change even when they are made to flow, and dilatant fluids that harden (the viscosity increases) when they are made to flow. Newtonian fluids are also called basic fluids due to the viscous behavior found in gases and general liquids. On the other hand, thixotropic fluids and dilatant fluids are generically called non-Newtonian fluids and are distinguished from Newtonian fluids, and the following equations are known as flow relation equations showing these three types of fluids.

## EQU1 ## γ = kτⁿ Where γ offset speed (s^-1), Τ is the shear stress (P
a) is an empirical formula, but the flow of the fluid depends on k and n.
It is generally known as an equation that characterizes dynamic phenomena. You
That is, the index n is 1 in Newtonian fluid and
N is 1 or less for Tannt fluid, and for thixotropic fluid
n becomes 1 or more. In addition, as n goes away from 1,
It can be called a tanto or thixotropic fluid. Also fixed
The number k is an index showing the static viscosity of the paint, and this value is large.
The higher the static viscosity value is, the lower the paint is,
When k or n is specified, the flow characteristics of the paint are determined
To be The constant k is a viscosity index, and Pa · s or P
Viscosity displayed in (poise), m^Two/ S and St (Stowe
It is different from the kinematic viscosity displayed in the box.

Therefore, the viscosity characteristic of the slurry for forming a negative electrode coating film of the non-aqueous secondary battery of the present invention is such that n is in the range of 1.1 to 4.5 when γ = 10 ^κ × τ ⁿ It is a thixotropic fluid. When n is less than 1.1, it is a coating having a thixotropic property but a liquid having a insufficient thixotropic property (slurry), which is a slurry which is difficult to handle by a coating machine such as a die coater or a blade coater in a coating forming process. On the other hand, when n exceeds 4.5, the thixotropic property is remarkable, that is, when the shear rate is large, the viscosity of the slurry is remarkably lowered (change in viscosity), which makes it difficult to handle. The constants n and k in the above empirical formula have a correlation from the viewpoint of easy-to-use paint. That is, when the constant n increases away from 1, the thixotropic property becomes remarkable, so even if the static viscosity value that the constant k means is high (the constant k is large), the shear rate that contributes to the slurry by the coating machine is high. For example, since the viscosity value when the slurry is applied is lowered, no problem will occur in use. The opposite is also true.
That is, when this view is applied to the relational expression of the present invention,
When n is large, .kappa. is allowed to be as small as -9.0, and conversely, if .kappa. is large as -1.0, it is allowed if n is small. The proper values of κ and n naturally vary depending on the type of coating machine.
It is common to all coating machines that there is an inverse proportional relationship between and.

It should be noted that γ (s ^-1 ) and τ (P
In the relational expression γ = 10 ^κ × τ ⁿ in a), κ is -1.0 to -9.
As a desirable mode for controlling 0 and n to be in the range of 1.1 to 4.5, the binder used in the slurry for forming a negative electrode coating film of a non-aqueous secondary battery is composed of an aqueous dispersion emulsion resin and a water-soluble polymer. The content of water-soluble polymer in the binder is 3
The amount of the binder is 0 to 65% by mass, and the amount of the binder compounded in the solid content of the slurry is 1 to 5% by mass. When the content of the water-soluble polymer in the binder is less than 30% by mass, the dispersibility of graphite particles is poor and it is difficult to obtain a uniform coating film.
It causes a decrease in charge and discharge capacity. On the other hand, when the content of the water-soluble polymer exceeds 65% by mass, the flexibility of the coating film is low, cracks may occur in the coating film when wound, and the charge / discharge capacity, especially at large current Causes capacity loss.
Therefore, the water-soluble polymer in the binder not only contributes to the dispersion as an organic component in the slurry, but also affects the film-forming property of the formed negative electrode coating film and contributes to the discharge capacity. It can be said that the emulsion resin is a material that contributes to the obtained coating film adhering to the substrate. The solid content of the slurry, that is, when the amount of the binder compounded in the total amount of the carbon material active material and the substantial solid content of the binder is less than 1% by mass, the obtained negative electrode coating film is easily peeled off from the substrate. As a result, the compounding amount is small. On the other hand, if the amount of the binder compounded exceeds 5% by mass, the charge / discharge capacity sharply decreases because the binder is not a material that absorbs lithium ions.

As the water-dispersed emulsion resin constituting the binder of the present invention, natural rubber (NR) latex having a minimum film forming temperature of 10 ° C. or lower, styrene-butadiene rubber (SBR) latex, butadiene rubber (BR) latex, Acrylonitrile-butadiene copolymer rubber (N
BR), methyl methacrylate / butadiene copolymer rubber (MBR) latex, styrene butadiene / styrene copolymer (SBS) latex, and acrylic ester resin emulsion, and one or more of these emulsion resins may be used. It can be used. As the water-soluble polymer, 1
The viscosity of a mass% aqueous solution at 25 ° C. is 200 to 2,500.
One or more selected from 0 mPa · s of sodium alginate, potassium alginate, ammonium alginate, propylene glycol alginate, carboxymethyl cellulose and its sodium salt or ammonium salt, hydroxyethyl cellulose, polyethylene oxide, polyvinyl alcohol, casein, sodium polyacrylate. is there. Similar to the above water-dispersed emulsion resin, it is possible to use a single substance or a mixture of the water-soluble polymers listed here.

Forming a coating film with a water-dispersed emulsion resin component is to aggregate emulsion particles constituting the emulsion resin, and the critical temperature for the aggregation of the particles is called the minimum film-forming temperature. This temperature is an important factor in handling emulsion-containing paint, and when the slurry is applied and dried at a temperature lower than this critical temperature to form a coating film, the emulsion particles only partially aggregate. In some cases, the coating film may be discontinuous, or it may simply become powder and cannot be formed into a coating film. Therefore, in order to form a coating film with a coating material containing an emulsion, it is necessary to handle at a minimum film forming temperature or higher. The upper limit of the minimum film-forming temperature of the water-dispersed emulsion resin used in the present invention is room temperature (25 ° C)
It is lower than 10 ° C. Therefore, when the slurry is applied to form a coating film, the coating material does not require any additional equipment such as special heating or constant temperature.

It should be noted that 2% of a 1 mass% aqueous solution of a water-soluble polymer.
The viscosity at 5 ° C. depends on the molecular weight of the water-soluble polymer, the bonding form of the polymer, and the like. Generally, the lower the viscosity value, the lower the molecular weight or the degree of polymerization. When the viscosity of the aqueous solution exceeds 2,500 mPa · s, the water-soluble polymer has a high degree of polymerization, the viscosity of the slurry increases, and the slurry has a low solid content and is difficult to handle. On the other hand, when the viscosity of the aqueous solution is less than 200 mPa · s, the viscosity of the slurry also decreases and the sedimentation of the particles becomes remarkable. The preferred viscosity range is 300 to 1,500 mPa · s.

In addition, the carbonaceous material applied to the slurry of the present invention contains 50 mass% or more of agglomerated graphite particles composed of phosphorus-like or flake-like natural graphite particles, and The graphite particle group has a cumulative 50% diameter (D50 diameter) of 10 to 25 μm in the laser light diffraction method.
m, the specific surface area in the nitrogen gas adsorption method is 2.5 to ⁵ m ²
/ G, apparent density in static method is 0.45 g / cm ³
As described above, the apparent density in the tap method is 0.70 g / cm
It is ³ or more.

When the value of D50 diameter (average particle diameter) is less than 10 μm, the particle diameter of the agglomerated graphite particles is too small, and in the obtained negative electrode coating film, the contact resistance between graphite particles is increased to form a coating film. The conductivity of the product tends to deteriorate. Therefore, as the battery characteristics, the charge / discharge capacity and the charge / discharge load characteristics are deteriorated, and the charge / discharge efficiency accompanying the decomposition of the electrolytic solution is decreased. On the other hand, when the value of D50 diameter exceeds 25 μm, the particle diameter of the graphite particle group is too large, and it takes time for the lithium ion in the negative electrode coating film to diffuse inside and outside the graphite during charging / discharging. As the discharge load characteristics deteriorate,
The formed coating film may have poor smoothness, and lithium may be locally deposited during charging.

Further, although there is a correlation with the value of this D50 diameter (average particle diameter), the specific surface area by the nitrogen gas adsorption method is 2.
When it is less than 5 m ² / g, the value of the specific surface area of the graphite particle group is low, and the particle group becomes coarse. Therefore, as a negative electrode coating film, it takes time for the diffusion of lithium ions into and out of graphite during charging / discharging, the charging / discharging load characteristics are deteriorated, and the smoothness of the coating film formed is deteriorated. Lithium may be deposited. On the other hand, when the specific surface area by the nitrogen gas adsorption method exceeds 5 m ² / g, the graphite particles become a fine particle group, and the contact resistance between the graphite particles increases as a negative electrode coating film, and the conductivity of the coating film formed is increased. Deteriorates, charge and discharge capacity and charge and discharge load characteristics decrease, charge and discharge efficiency decreases with the decomposition of the electrolytic solution, aggregation tends to proceed to a particle group with a low bulk density, and the specific surface area is It is not preferable if it is larger than the value.

Further, the aggregated graphite particle group in the present invention
Apparent density by static method of 0.45g / cm^Threethat's all,
Apparent density by tap method is 0.70g / cm^ThreeAbove
is there. Apparent density by static method and appearance by tap method
The coating density is measured by the pigment test method (JIS K 51
01). The static method and the
The apparent density by tapping and tapping is the Hosokawa Micron
It was measured using the Udertester PT-R type.
It The apparent density is measured by the static method by passing it through a sieve mesh.
Put the sample in the receiver and the volume is 100 cm^ThreeBecame
It is evaluated by measuring the mass of mushrooms. On the other hand
The apparent density measurement method using the tap method
After tapping the receiver 180 times while putting it in the container,
Product 100cm^ThreeEvaluation by measuring the mass per hit
To do. Apparent density 0.45g / cm by static method^ThreeOh
And apparent density of 0.70 g / cm by tap method^Threeof
The value is the lower limit value of the graphite particle group applied to the present invention.
It To meet the demand for higher energy density of lithium-ion batteries
On the other hand, increasing the packing density of the active material, in other words
For example, high density coating is essential. For that, you can
It is necessary to form only thick coatings. The inventors
As a result of the investigation, the solid content of the slurry for forming the coating film
A good coating film can be formed when the content is 45% by mass or more.
Found. To achieve its solids content, stand still
Apparent density by the method is 0.45g / cm^ThreeTap
Apparent density by method is 0.70g / cm ^ThreeGreater than or equal to
I found it to be better. Also, less than these apparent densities
, The fluctuation of the film thickness during coating becomes large, resulting in sufficient adhesion strength.
The amount of binder needed to obtain high
There is a concern that this will cause a decrease in capacity.

[0017]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to the examples. <Examples 1 to 5> (Preparation of slurry) Specific surface area 4.2 m ² / g, D50 particle size 19.3 μm, apparent density 0.44 g / by static method
cm ³ , apparent density by tap method 0.85 g / cm ³
The lumpy graphite particles composed of the scaly natural graphite of Table 1
A slurry was prepared by mixing the water-dispersed emulsion shown in 1) with a binder composed of a water-soluble resin.

[0018]

[Table 1]

(Flowability) These pastes were placed on a flat plate of a rheometer (HAAKE-PK100), and a cone type rotor (PK: 2-1 °, diameter 2 cm, cone angle 1 °) was used at 25 ° C. The shear rate was increased to 3,000 s ^{−1 in} 180 seconds, and the shear stress at each shear rate was measured to evaluate the fluidity. (Coating) In a 25 ° C. environment, these slurries were applied onto a rolled copper foil serving as a current collector by using a doctor blade with a gap of 200 μm, dried at 120 ° C. for 10 minutes, and then rolled with a roll press. The negative electrode coating film was 0.5 g / cm ³ . (Adhesiveness) A cellophane tape having a width of 18 mm was attached on the negative electrode coating film and pressure-bonded with a load of 2 kg, and then the load required to peel off the cellophane tape was measured with a push-pull gauge. Further, the peeled (destructed) state of the negative electrode coating film was observed. (Electrode characteristics) A negative electrode coating film was punched together with a copper foil with a punch to prepare an electrode. A coin-shaped model cell was prepared using metallic lithium as a counter electrode and 1M-LiPF ₆ / EC (ethylene carbonate) + DMC (dimethyl carbonate) as an electrolyte, and 0.01 V (at a current density of 0.5 mA / cm ² ). vs. Li ^/ Li ⁺ ) lithium was occluded (charged) in the negative electrode at a constant current to obtain the charge capacity. The initial discharge capacity was determined by discharging to 1.1 V (vs. Li / Li ⁺ ) at a constant current of 0.5 mA / cm ² . Furthermore, after charging at 0.5 mA / cm ² , 6 m
1.1 V (vs. Li / Li ⁺ ) at a current density of A / cm ^2.
Discharge capacity up to 0.5mA / c
The ratio with the capacity when discharged at m ² was obtained, and the discharge load characteristic (discharge rate) was evaluated. Table 2 shows the results of the above-described various evaluations for each graphite sample.

[0020]

[Table 2] It should be noted that in each of the samples of the examples within the scope of the present invention described in the table, the coatability, the strength of the obtained coating film and the electrode characteristics were all good.

<Comparative Examples 1 to 7> The materials shown in Tables 3 and 5 were used as comparative samples and evaluated by the same measuring method as in the examples. The evaluation results are shown in Table 4 as Comparative Examples 1 to 4 and Table 6 as Comparative Examples 5 to 7.

[Table 3]

[0022]

[Table 4]

In Sample 11 (Comparative Example 1), the viscosity of a 1% by weight aqueous solution of a water-soluble polymer was out of the range, and since κ was as small as -9.8, sedimentation of particles was remarkable and the viscosity was low. The coating film was scratched. In Sample 12 (Comparative Example 2), the viscosity of the 1% by mass aqueous solution of the water-soluble polymer was out of the range, and the κ and n values were within the ranges of the present invention, but the solid content of the slurry was low and the slurry was not coated. Bleeding occurred. In Samples 13 (Comparative Example 3) and 14 (Comparative Example 4), the content of the water-soluble polymer in the binder was out of the range, and in Sample 13, the coating film was scratched. The discharge load characteristics deteriorated due to the large number.

[0024]

[Table 5]

[0025]

[Table 6]

Sample 21 (Comparative Example 5) has a small amount of binder compounded in the solid content of the slurry, so that the coating film is scratched and the adhesion strength is low. In Sample 22 (Comparative Example 6), the amount of the binder was large and the discharge load characteristics were deteriorated. In Sample 23 (Comparative Example 7), since the minimum film forming temperature of the emulsion was high, sufficient film formation could not be obtained and the adhesion of the coating film was weak, causing deterioration of discharge capacity and discharge load.

[0027]

By using the slurry of the present invention, the coating strength and coating density of the battery electrode are improved,
In addition, it is possible to obtain a negative electrode of a non-aqueous secondary battery having excellent various electrode characteristics.

Claims (4)

[Claims] 1. A slurry for forming a negative electrode coating film of a non-aqueous secondary battery, the solid content of which is a carbon material active material and a binder, and the medium of which is water. In the relationship between the shear rate (γ s ^-1 ) and the shear stress (τ Pa), γ = 10 ^κ × τ ⁿ
And κ is in the range of -1.0 to -9.0, and n
Is in the range of 1.1 to 4.5, the slurry for forming a negative electrode coating film of a non-aqueous secondary battery. 2. The binder is composed of a water-dispersed emulsion resin and a water-soluble polymer, the content of the water-soluble polymer in the binder is in the range of 30 to 65% by mass, and the solid content of the slurry. The content of the binder in the content is in the range of 1 to 5% by mass, and the water-dispersed emulsion resin is a natural rubber latex having a minimum film forming temperature of 10 ° C. or less, styrene-butadiene rubber latex, butadiene rubber latex, acrylonitrile One or more selected from butadiene copolymer rubber latex, methyl methacrylate / butadiene copolymer rubber latex, styrene butadiene / styrene copolymer latex and acrylic ester resin emulsion, wherein the water-soluble polymer is a 1% by mass aqueous solution. Sodium alginate having a viscosity at 25 ° C. of 200 to 2,500 mPa · s, Potassium alginate, ammonium alginate,
1. One or more selected from propylene glycol alginate, carboxymethyl cellulose and its sodium or ammonium salts, hydroxyethyl cellulose, polyethylene oxide, polyvinyl alcohol, casein, and sodium polyacrylate.
The slurry for forming a negative electrode coating film of the non-aqueous secondary battery as described in 1. 3. The carbon material active material comprises a group of massive graphite particles composed of phosphorus-like or flake-like natural graphite particles.
0 mass% or more, and the agglomerated graphite particle group is accumulated 5 times in the laser light diffraction method.
0% diameter (D50 diameter) is 10 to 25 μm, specific surface area in nitrogen gas adsorption method is 2.5 to ⁵ m ² / g, apparent density in stationary method is 0.45 g / cm ³ or more, apparent density in tap method is The slurry for forming a negative electrode coating film of a non-aqueous secondary battery according to claim 1, which has a content of 0.70 g / cm ³ or more. 4. The viscous properties of the slurry for forming a negative electrode coating film of a non-aqueous secondary battery in which a main constituent material is a carbon material active material, a binder and an aqueous medium are shear rate (γ s ^-1 ) and shear stress ( τ Pa) in relation to γ = 10 ^κ × τ ⁿ , κ is in the range of -1.0 to -9.0, and n is in the range of 1.1 to 4.5. A method for preparing a slurry for forming a negative electrode coating film of a battery.