KR20190068236A - Method for modifying graphite-based particle - Google Patents

Abstract

The present invention relates to a method for modifying graphite-based particles capable of increasing tap density of a graphite-based conductive material, which comprises a step of introducing negative electrode slurry including graphite-based particles and a binder into a mortar, and stirring the negative electrode slurry by using a pestle.

Description

[0001] METHOD FOR MODIFYING GRAPHITE-BASED PARTICLE [0002]

More particularly, the present invention relates to a method for modifying a graphite-based particle, wherein the graphite-based particle modifying method includes a step of putting a negative electrode slurry containing graphite-based particles and a binder into a bowl and stirring the negative electrode slurry using a pillar .

Due to the rapid increase in the use of fossil fuels, the demand for the use of alternative energy or clean energy is increasing. As a part of this, the most active field of research is electric power generation and storage.

At present, a typical example of an electrochemical device utilizing such electrochemical energy is a secondary battery, and the use area thereof is gradually increasing. 2. Description of the Related Art [0002] Recently, as technology development and demand for portable devices such as portable computers, portable phones, cameras, and the like have increased, the demand for secondary batteries as energy sources has been rapidly increasing. Among such secondary batteries, high energy density, Have been studied, and they have been commercialized and widely used.

Generally, the secondary battery is composed of an anode, a cathode, an electrolyte, and a separator. The negative electrode includes a negative electrode active material layer, and the negative electrode active material layer may include a conductive material, a binder and the like together with the negative electrode active material for inserting and desorbing lithium ions from the positive electrode. The binder prevents the particles of the negative electrode active material, the conductive material and the like from being separated from the negative electrode active material layer, thereby improving the electrode adhesion.

On the other hand, graphite particles are used as an anode active material or a conductive material. However, in the case of the graphite-based particles having a low tap density, there is a problem that the adhesion force with the binder is weak and the electrode adhesion force is difficult to maintain a desirable level. To solve this problem, techniques for controlling the kind of binder, weight average molecular weight, and the like have been introduced.

Alternatively, in order to improve the tap density of the graphite-based conductive material, a step of sphering the graphite-based conductive material before the graphite-based conductive material is charged into the negative electrode slurry for producing the negative electrode active material layer may be considered. However, such a method adds a separate process, which complicates the manufacturing process and raises the manufacturing cost.

Thus, there is a need for a method that can increase the tap density of the graphite conductive material without any additional process.

A problem to be solved by the present invention is to provide a method capable of increasing the tap density of the graphite-based conductive material in a conventional process including a mixing (stirring) process of the negative electrode slurry without any additional process.

According to one embodiment of the present invention, there is provided a graphite particle modification method comprising the steps of charging a negative electrode slurry containing graphite particles and a binder and stirring the negative electrode slurry using a mortar.

According to the present invention, in the conventional process including the mixing (stirring) process of the negative electrode slurry, the tap density of the graphite conductive material can be increased without any additional process. This simplifies the manufacturing process and minimizes the increase in manufacturing cost. Further, in the produced negative electrode, the electrode adhesion can be improved.

1 is a photograph of the graphite-based particles of Example 1 modified according to the present invention.
2 is a photograph of the graphite-based particles of Example 2 modified according to the present invention.
3 is a photograph of graphite-based particles of Comparative Example 1 to which a conventional stirring method (using a planetary blade) is applied.
4 is a photograph of graphite-based particles of Comparative Example 2 to which a conventional stirring method (using a planetary blade) is applied.
5 is a graph showing the results of the electrode adhesion test of Examples 1 and 2 and Comparative Examples 1 and 2.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In this specification, the terms "comprising," "comprising," or "having ", and the like are intended to specify the presence of stated features, But do not preclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

The graphite-based particle modification method according to an embodiment of the present invention may include the steps of charging a negative electrode slurry containing graphite-based particles and a binder into a bowl, and stirring the negative electrode slurry using a pestle.

The negative electrode used in the secondary battery includes a current collector and a negative electrode active material layer disposed on the current collector. The negative electrode slurry is used to produce the negative electrode active material layer. Specifically, the negative electrode slurry may be disposed on the current collector and dried to form a negative electrode active material layer.

The negative electrode slurry may include graphite particles and a binder.

The graphite particles may serve as a negative electrode active material for the insertion and desorption of lithium ions, and may serve as a conductive material for improving the electrical conductivity of the negative electrode active material layer. That is, the graphite-based particles may be a negative electrode active material, and may be a conductive material.

The graphite particles before the application of the graphite particle modification method, that is, the graphite particles in the negative electrode slurry put into the bowl, are composed of block-type artificial graphite, powder-type artificial graphite, scaly natural graphite and spherical natural graphite And the like. Specifically, the graphite-based particles may be block-type artificial graphite or a mixture of block-type artificial graphite and powder-type artificial graphite.

The average particle size (D ₅₀ ) of the graphite-based particles may be 3 탆 to 10 탆, and may be 3 탆 to 7 탆. When the above range is satisfied, the graphite-based particles can be smoothly modified. In the present specification, the average particle diameter (D ₅₀ ) can be defined as a particle diameter corresponding to 50% of the volume accumulation amount in the particle diameter distribution curve of the particles. The average particle diameter (D ₅₀ ) can be measured using, for example, a laser diffraction method. The laser diffraction method generally enables measurement of a particle diameter of several millimeters from a submicron region, resulting in high reproducibility and high degradability.

The tap density of the graphite particles in the negative electrode slurry injected into the bowl may be less than 0.84 g / cc, specifically 0.83 g / cc or less, more specifically 0.30 g / cc to 0.82 g / cc. When the graphite particles having a tap density in the above range are used for the negative electrode active material layer, the binder and the graphite particles are not smoothly bonded, and thus the graphite particles are easily separated from the negative electrode active material layer. Accordingly, it is an object of the present invention to increase the tap density of the graphite-based particles having the tap density. The tap density can be measured using a Tapdenser KYT-4000 (SEISHIN) and corresponds to the density measured after 1000 tapings.

The binder may be selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidenefluoride, polyacrylonitrile, polymethylmethacrylate, poly Polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), liquor, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, And may include at least any one selected from the group consisting of polyvinylidene fluoride (EPDM), styrene butadiene rubber (SBR), fluorine rubber, poly acrylic acid, and materials in which hydrogen thereof is substituted with Li, Na, Ca, And may include various copolymers thereof.

In addition to the graphite particles, the negative electrode active material may be further included in the negative electrode slurry. The negative active material may be a compound capable of reversibly intercalating and deintercalating lithium. Specific examples thereof include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber and amorphous carbon; Metal compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys or Al alloys; _{SiO β (0 <β <2} ), SnO 2, vanadium oxide, which can dope and de-dope a lithium metal oxide such as lithium vanadium oxide; Or a composite containing the metallic compound and the carbonaceous material such as Si-C composite or Sn-C composite, and any one or a mixture of two or more thereof may be used. Also, a metal lithium thin film may be used as the negative electrode active material. The carbon material may be both low-crystalline carbon and high-crystallinity carbon. Examples of the low-crystalline carbon include soft carbon and hard carbon. Examples of the highly crystalline carbon include natural graphite, artificial graphite, artificial graphite or artificial graphite, Kish graphite graphite, pyrolytic carbon, mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar coke derived cokes).

When stirring the negative electrode slurry using the pestle, the pressure applied to the negative electrode slurry by the pestle may be 0.5 kg / cm ² to 2 kg / cm ² , and specifically, 1 kg / cm ² to 2 kg / cm ² And more specifically 1.5 kg / cm ² to 2 kg / cm ² . When the pressure is satisfied, the graphite-based particles can be smoothly modified. The pressure can be measured in the following manner, though not necessarily limited thereto. The pressure of the negative electrode slurry is measured by dividing the weight of the negative electrode slurry by the end surface area of the pellet contacting the negative electrode slurry while stirring the negative electrode slurry with the pellet.

The tap density of the graphite-based particles modified by the graphite-based particle modifying method may be 0.9 g / cc or more, specifically 0.91 g / cc to 0.95 g / cc. When the above-mentioned range is satisfied, the binding force between the binder and the graphite-based particles is improved in the prepared negative electrode active material layer, and desorption of the graphite-based particles can be suppressed. The tap density can be measured after washing the negative electrode slurry, filtering and drying the graphite particles.

The present invention is not limited to adding a separate process to increase the tap density of graphite-based particles, but it is possible to improve the dispersion of particles in the negative electrode slurry by modifying a conventional negative electrode slurry mixing (stirring) method, And the tap density can be increased. This simplifies the manufacturing process and minimizes the increase in manufacturing cost. Further, in the produced negative electrode, the electrode adhesion can be improved.

The negative electrode according to another embodiment of the present invention may be a negative electrode manufactured through the negative electrode slurry including the graphite-based particles of the above-described embodiment.

The negative electrode may include a current collector and a negative electrode active material layer disposed on the current collector. The negative electrode active material layer may include a binder as well as the graphite-based particles, and may further include an anode active material other than the graphite-based particles. In some cases, the negative electrode active material layer may further include a conductive material other than the graphite-based particles.

The current collector is not particularly limited as long as it has electrical conductivity without causing a chemical change in the battery. For example, the current collector may be made of copper, stainless steel, aluminum, nickel, titanium, sintered carbon, or a surface of aluminum or stainless steel surface treated with carbon, nickel, titanium or silver. Specifically, a transition metal that adsorbs carbon well such as copper or nickel can be used as a current collector. The current collector may have a thickness of 6 to 20 탆, but the thickness of the current collector is not limited thereto.

The conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon black such as carbon black, acetylene black, Ketjen black, channel black, panes black, lamp black, and thermal black; Conductive fibers such as carbon fiber and metal fiber; Conductive tubes such as carbon nanotubes; Metal powders such as fluorocarbon, aluminum and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The secondary battery according to another embodiment of the present invention may include a cathode, an anode, a separator interposed between the anode and the cathode, and an electrolyte, and the cathode is the same as the cathode described above. Since the negative electrode has been described above, a detailed description thereof will be omitted.

The positive electrode may include a positive electrode collector and a positive electrode active material layer formed on the positive electrode collector and including the positive electrode active material.

In the anode, the cathode current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and for example, a metal such as stainless steel, aluminum, nickel, titanium, sintered carbon, , Nickel, titanium, silver, or the like may be used. In addition, the cathode current collector may have a thickness of 3 to 500 탆, and fine unevenness may be formed on the surface of the current collector to increase the adhesive force of the cathode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The cathode active material may be a commonly used cathode active material. Specifically, the cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ) or lithium nickel oxide (LiNiO ₂ ) or a compound substituted with one or more transition metals; Lithium iron oxides such as LiFe ₃ O ₄ ; Formula _{Li 1 + c1 Mn 2-c1} O 4 (0≤c1≤0.33), LiMnO 3, the lithium manganese oxide such as LiMn ₂ O _3, LiMnO _2; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula LiNi _1-c2 M _c2 O ₂ expressed as (where, M is at least one, satisfies 0.01≤c2≤0.3 selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B and Ga) &Lt; / RTI &gt; Ni-type lithium nickel oxide; Formula _{LiMn 2-c3 M c3 O 2} ( where, M is Co, Ni, Fe, Cr, Zn , and is at least one selected from the group consisting of Ta, satisfies 0.01≤c3≤0.1) or Li ₂ Mn ₃ MO ₈ (wherein M is at least one selected from the group consisting of Fe, Co, Ni, Cu and Zn); And LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion. However, the present invention is not limited to these. The anode may be Li-metal.

The cathode active material layer may include a cathode conductive material and a cathode binder together with the cathode active material described above.

At this time, the positive electrode conductive material is used for imparting conductivity to the electrode, and the positive electrode conductive material can be used without particular limitation as long as it has electron conductivity without causing chemical change. Specific examples thereof include graphite such as natural graphite and artificial graphite; Carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black and carbon fiber; Metal powder or metal fibers such as copper, nickel, aluminum and silver; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; And polyphenylene derivatives. These may be used alone or in admixture of two or more.

In addition, the positive electrode binder improves adhesion between the positive electrode active material particles and adhesion between the positive electrode active material and the positive electrode collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose ), Starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, and various copolymers thereof. One kind or a mixture of two or more kinds of them may be used.

The separator separates the cathode and the anode and provides a passage for lithium ion. The separator can be used without any particular limitation as long as it is used as a separator in a secondary battery. In particular, the separator can be used with low resistance against electrolyte migration, . Specifically, porous polymer films such as porous polymer films made of polyolefin-based polymers such as ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers and ethylene / methacrylate copolymers, May be used. Further, a nonwoven fabric made of a conventional porous nonwoven fabric, for example, glass fiber of high melting point, polyethylene terephthalate fiber, or the like may be used. In order to secure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer material may be used, and the separator may be selectively used as a single layer or a multilayer structure.

Examples of the electrolyte include an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte that can be used in the production of a lithium secondary battery, but are not limited thereto.

Specifically, the electrolyte may include a non-aqueous organic solvent and a metal salt.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butylolactone, Tetrahydrofuran, tetrahydrofuran, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, Examples of the organic solvent include methyl acetate, phosphoric acid triester, trimethoxy methane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, Propylenic organic solvents such as methylmethyl, ethylpropionate and the like can be used.

In particular, ethylene carbonate and propylene carbonate, which are cyclic carbonates in the carbonate-based organic solvent, can be preferably used because they have high permittivity as a high viscosity organic solvent and dissociate the lithium salt well. To such a cyclic carbonate, dimethyl carbonate and diethyl carbonate When a low viscosity and a low dielectric constant linear carbonate are mixed in an appropriate ratio, an electrolyte having a high electric conductivity can be prepared, and thus it can be used more preferably.

The metal salt may be a lithium salt, and the lithium salt may be soluble in the non-aqueous electrolyte. Examples of the anion of the lithium salt include F ^- , Cl ^- , I ^- , NO ₃ ^- , N _{^{) 2 -, BF 4 -,}} ClO 4 -, PF 6 -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF - ^{_{, (CF 3) 6 P -}} , CF 3 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -, (FSO 2) 2 N -, CF 3 CF 2 (CF 3) 2 _{^{CO -, (CF 3 SO 2}} ) 2 CH -, (SF 5) 3 C -, (CF 3 SO 2) 3 C -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO 2 -, CH 3 At least one selected from the group consisting of CO ₂ ^- , SCN ^- and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- can be used.

In addition to the electrolyte components, the electrolyte may contain, for example, a haloalkylene carbonate-based compound such as difluoroethylene carbonate or the like, pyridine, triethanolamine, or the like for the purpose of improving lifetime characteristics of the battery, Ethyl phosphite, triethanol amine, cyclic ether, ethylenediamine, glyme, hexametriamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, At least one additive such as benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol, benzyl alcohol,

According to another embodiment of the present invention, there is provided a battery module including the secondary battery as a unit cell and a battery pack including the same. Since the battery module and the battery pack include the secondary battery having a high capacity, high speed-rate characteristics, and a cycling characteristic, the battery module and the battery pack can be suitably used as a middle- or large-sized device selected from the group consisting of electric vehicles, hybrid electric vehicles, plug- As shown in FIG.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the appended claims. Such variations and modifications are intended to be within the scope of the appended claims.

Examples and Comparative Examples

Example 1: Preparation of negative electrode

(1) Preparation of negative electrode slurry

A mixture of graphite artificial graphite having an average particle diameter (D ₅₀ ) of 6.4 μm and a tap density of 0.39 g / cc and powdery artificial graphite having an average particle diameter (D ₅₀ ) of 22 μm and a tap density of 0.87 g / 18) was used as graphite particles, and the graphite-based particles had a tap density of 0.83 g / cc. Further, Carboxyl methyl cellulose (CMC) and Styrene butadiene rubber (SBR) were used as binders. The block-type artificial graphite, the powdered artificial graphite, and CMC were put into a bowl having a volume capacity of 100 ml, and then stirred at a pressure of 1 kg / cm ² through a pestle. Thereafter, CMC was further added to the bowl and stirred at the same pressure. SBR was then added to the bowl and stirred at the same pressure. In the agitated mixture, the weight ratio of the block type artificial graphite, the powder type artificial graphite, CMC and SBR was 5: 90: 2: 3. To 18 g of the mixture, 2 g of deionized water was added and stirred at the same pressure to prepare an anode slurry. The total stirring time was 0.2 hours. Thereafter, the tap density of the graphite-based particles measured using Tapdenser KYT-4000 (SEISHIN) (1,000 tapping) was 0.92 g / cc.

(2) Application and drying of the negative electrode slurry

The agitated negative electrode slurry was applied to a copper (Cu) metal thin film as an anode current collector having a thickness of 20 mu m and dried. The temperature of the circulated air was 60 ° C. Subsequently, the sheet was rolled and dried in a vacuum oven at 130 DEG C for 24 hours, and then was applied in the form of a sheet having a width of 2 cm and a length of 12 cm to produce a negative electrode including a negative active material layer. The prepared anode active material layer density was 1.6 g / cc.

Example 2: Preparation of negative electrode

(1) Preparation of negative electrode slurry

A mixture of block-type artificial graphite having an average particle diameter (D ₅₀ ) of 3.01 μm and a tap density of 0.31 g / cc and powder-like artificial graphite having an average particle diameter (D ₅₀ ) of 22 μm and a tap density of 0.87 g / 18) was used as graphite particles, and the graphite-based particles had a tap density of 0.82 g / cc. Further, Carboxyl methyl cellulose (CMC) and Styrene butadiene rubber (SBR) were used as binders. The block-type artificial graphite, the powdered artificial graphite, and CMC were put into a bowl having a volume capacity of 100 ml, and then stirred at a pressure of 1 kg / cm ² through a pestle. Thereafter, CMC was further added to the bowl and stirred at the same pressure. SBR was then added to the bowl and stirred at the same pressure. In the agitated mixture, the weight ratio of the block type artificial graphite, the powder type artificial graphite, CMC and SBR was 5: 90: 2: 3. To 18 g of the mixture, 2 g of deionized water was added and stirred at the same pressure to prepare an anode slurry. The total stirring time was 0.2 hours. Thereafter, the tap density of the graphite-based particles measured using a Tapdenser KYT-4000 (SEISHIN Co., Ltd.) (1,000 tapping) was 0.91 g / cc.

(2) Application and drying of the negative electrode slurry

The negative electrode slurry was applied to a current collector in the same manner as in Example 1 and dried to prepare the negative electrode of Example 2. [

Comparative Example 1: Preparation of negative electrode

(1) Preparation of negative electrode slurry

Same as Example 1, except that the mixture and slurry were not agitated using a mortar and a bowl but agitated at 70 rpm through a planetary blade (TK-mixer). At this time, the total stirring time was 0.5 hour. Thereafter, the tap density of the graphite-based particles measured by using Tapdenser KYT-4000 (SEISHIN) (1,000 tapping) was 0.87 g / cc.

(2) Application and drying of the negative electrode slurry

The negative electrode slurry was coated on a current collector and dried in the same manner as in Example 1 to prepare a negative electrode of Comparative Example 1. [

Comparative Example 2: Preparation of negative electrode

(1) Preparation of negative electrode slurry

Same as in Example 2 except that the mixture and slurry were not agitated using a mortar and a bowl but agitated at 70 rpm through a planetary blade (TK-mixer). At this time, the total stirring time was 0.5 hour. Thereafter, the tap density of the graphite-based particles measured using Tapdenser KYT-4000 (SEISHIN) (1,000 tapping) was 0.88 g / cc.

(2) Application and drying of the negative electrode slurry

The negative electrode slurry was coated on a current collector and dried in the same manner as in Example 2 to prepare a negative electrode of Comparative Example 2. [

Experimental Example 1: Evaluation of electrode adhesion

For each of the negative electrodes of Examples 1 and 2 and Comparative Examples 1 and 2, the negative electrode was fixed to a central portion of a 26 mm x 76 mm slide glass using a tape, and the collector was peeled off at a rate of 20 m / min using a UTM The 90 degree peel strength was measured. The peeling strength was measured four times and the average value was determined. This is shown in FIG.

Referring to FIG. 5, it can be seen that the electrode adhesion of Example 1 was improved by 50% to 150% as compared with Comparative Example 1, and that of Example 2 was improved compared to Comparative Example 2.

Considering that the tap density of the graphite-based particles of Examples 1 and 2 is higher than the tap density of the graphite-based particles of Comparative Examples 1 and 2, in comparison with the conventional mixing method using a planetary blade or the like, , It can be seen that the tap density of the graphite particles can be further improved. Further, it can be confirmed that such a result can lead to improvement of the electrode adhesion.

Claims (7)

Adding a negative electrode slurry containing graphite particles and a binder to a bowl, and stirring the negative electrode slurry using a pestle.
The method according to claim 1,
Wherein the graphite particles in the negative electrode slurry injected into the bowl are at least one selected from the group consisting of block-type artificial graphite, powder-type artificial graphite, scaly natural graphite, and spherical natural graphite.
The method according to claim 1,
Wherein the average particle diameter (D ₅₀ ) of the graphite particles in the negative electrode slurry charged into the bowl is 3 탆 to 10 탆.
The method according to claim 1,
Wherein the tap density of the graphite particles in the negative electrode slurry injected into the bowl is less than 0.84 g / cc.
The method according to claim 1,
And the pressure applied to the negative electrode slurry by the pestle is 0.5 kg / cm ² to 2 kg / cm ² .
The method according to claim 1,
Wherein the tap density of the graphite-based particles modified by the graphite-based particle modifying method is 0.9 g / cc or more.
The method according to claim 1,
Wherein the negative electrode slurry further comprises a negative electrode active material.

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