KR101752530B1 - Method for manufacturing cathode electrode and cathode electrode manufactured by the same - Google Patents

Abstract

The present invention relates to a method for manufacturing an anode capable of increasing the adhesion between a positive electrode collector and a positive electrode active material layer while increasing the speed of a positive electrode active material layer forming process, an electrode manufactured from the positive electrode, and a lithium secondary battery comprising the electrode. As a result, the manufacturing process of the anode can increase the speed of the coating process, thereby improving the productivity. At the same time, the cathode active material can be uniformly distributed without being densely packed on the cathode active material layer, And the performance of the lithium secondary battery using the same can be improved. In addition, the binder contained in the positive electrode active material layer may be appropriately distributed at the interface between the positive electrode active material layer and the positive electrode collector, so that the positive electrode desorption phenomenon can be suppressed.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a cathode,

The present invention relates to a method of manufacturing an anode capable of increasing the adhesion between a positive electrode collector and a positive electrode active material layer while increasing the speed of the positive electrode active material layer formation process, a d anode produced therefrom, and a lithium secondary battery comprising the same.

Recently, in response to the rapid development of the communication industry such as electronic industry and various information communication including mobile communication, in order to meet the demand of light and short life of electronic devices, a variety of products such as notebooks, netbooks, tablet PCs, mobile phones, smart phones, PDAs, Portable electronic products, and communication terminals have been widely popularized, and development of a battery that is a driving power source for these devices is also increasing.

In addition, with the development of electric vehicles such as hydrogen electric vehicles, hybrid electric vehicles and fuel cell vehicles, great attention has been paid to the development of batteries having high performance, large capacity, high density, high output and high stability, The development of batteries is also a big issue.

Batteries that convert chemical energy into electrical energy are divided into primary cells, secondary cells, fuel cells, and solar cells depending on the type and characteristics of basic materials.

The dual primary cells produce energy through irreversible reactions such as manganese batteries, alkaline batteries, and mercury batteries. However, they have a disadvantage in that they are large in capacity but can not be recycled, and thus have various problems such as energy inefficiency and environmental pollution.

The secondary battery includes a lead-acid battery, a nickel-metal hydride battery, a nickel-cadmium battery, a lithium ion battery, a lithium polymer battery, and a lithium metal battery and repeats charge and discharge using reversible mutual conversion of chemical energy and electric energy. As a chemical cell that can be operated by reversible reaction, it has advantages of recycling and environment-friendly.

The secondary cell has four basic components: a positive electrode and a negative electrode, a separator and an electrolyte.

The positive and negative electrodes have positive and negative potentials, respectively, as electrodes for conversion and storage of energy such as oxidation / reduction. The separator is positioned between the anode and the cathode to maintain electrical insulation and provide a path for charge transport. In addition, the electrolyte acts as a mediator of telephone transfer.

Each of the electrodes includes each of the electrode active materials. Each of the active materials used in a lithium secondary battery, which is currently the most popular among the secondary batteries, is as follows.

Lithium cobalt oxide (Li _x CoO ₂ ), lithium nickel oxide (Li _x NiO ₂ ), lithium nickel cobalt oxide (Li _x (NiCo) O ₂ ), and the like are used as the cathode active material. Oxides such as lithium nickel cobalt manganese oxide (Li _x (NiCoMn) O ₂ ), spinel type lithium manganese oxide (Li _x Mn ₂ O ₄ ), manganese dioxide (MnO ₂ ), or lithium iron phosphate (Li _x FePO ₄ ) Olivine type or NASICON type phosphates, silicates, sulfates or polymer materials such as manganese phosphate (Li _x MnPO ₄ ) and the like can be used.

As the negative electrode active material, a compound capable of intercalating lithium metal, its alloy or lithium ion can be used. A polymer material or a carbon material can be used, and a graphite system such as artificial or natural graphite, Carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon nanotubes (CNTs), carbon nanotubes (CNTs), graphite- Carbon based materials such as carbon nonawall (CNW), etc. may be used.

On the other hand, the positive electrode can be generally manufactured by applying a positive electrode active material slurry on a positive electrode current collector and drying to form a positive electrode active material layer. The positive electrode active material slurry is generally produced by mixing a positive electrode active material, a conductive material, Additives. Specifically, the anode can be manufactured by wheating and mixing each material constituting the cathode active material slurry, coating and drying the cathode active material, and then pressing the anode active material slurry .

The coating and drying is a step of applying the slurry of the cathode active material to the cathode current collector and drying to obtain a cathode composed solely of the solid component, and the dispersion medium contained in the cathode active material slurry is evaporated.

In this case, when the coating and drying, particularly the drying, is performed rapidly, the dispersion medium contained in the slurry of the positive electrode active material evaporates and the binder and the positive electrode active material are attached to each other so that the binder is concentrated on the upper part of the separable positive electrode active material layer. The binder is reduced at a portion contacting with the positive electrode current collector, resulting in a phenomenon that the adhesion between the positive electrode current collector and the positive electrode active material layer is deteriorated and the separator is desorbed. In addition, the cathode active material may not be uniformly distributed in the cathode active material layer, and the battery active material may be densely packed at an upper portion or a lower portion of the cathode active material layer, thereby deteriorating the battery performance of the lithium secondary battery. Accordingly, in order to uniformly place the cathode active material at a desired portion while increasing the adhesion between the cathode current collector and the cathode active material layer and preventing the anode from being desorbed, adjustment of the coating and drying speed may be important.

Under the above background, the present inventors have found that, in the process of coating and drying the slurry of the cathode active material to improve the productivity in the process of forming the cathode active material layer, the adhesion between the cathode current collector and the cathode active material layer is increased, The method comprising the steps of applying and drying a slurry of a cathode active material on one surface of a cathode current collector and performing a magnetic treatment in at least one of the application and the drying to form a cathode, It is possible to improve the adhesion between the positive electrode current collector and the positive electrode active material layer and to uniformly position the positive electrode active material at a proper position and to improve the performance of the lithium secondary battery.

JP 2014-007037 A

It is an object of the present invention to provide a method of manufacturing an anode capable of increasing the adhesion between the cathode current collector and the cathode active material layer while increasing the speed of the cathode active material layer forming process.

Another object of the present invention is to provide a positive electrode produced by the above-described production method.

Still another object of the present invention is to provide a lithium secondary battery comprising the above-described anode, cathode, and separator interposed between the anode and the cathode.

According to an aspect of the present invention, there is provided a method of manufacturing a positive electrode current collector, comprising the steps of: (1) preparing a positive electrode current collector coated with a slurry of a positive electrode active material slurry on one surface of a positive electrode current collector; And drying the cathode current collector coated with the cathode active material slurry (step 2), wherein the cathode active material slurry includes a cathode active material having a first magnetic property, Wherein the first and second magnetic properties are performed while applying a second magnetic property to a lower surface of a surface opposite to one surface of a cathode current collector to which the active material slurry is applied, and wherein the first and second magnetic properties are opposite to each other do.

Further, the present invention provides a positive electrode prepared from the above-mentioned production method.

In addition, the present invention provides a lithium secondary battery including the positive electrode, the negative electrode, and the separator interposed between the positive electrode and the negative electrode.

The method of manufacturing an anode according to the present invention can increase the speed of the coating process by performing the magnetic coating opposite to the magnetic property of the cathode active material at one or more stages of the coating and drying in the coating process including coating and drying The productivity can be improved. At the same time, the binder can be appropriately distributed at the interface between the positive electrode active material layer and the positive electrode collector.

In addition, since the positive electrode according to the present invention is manufactured by the above-described method, the positive electrode active material contained in the positive electrode active material layer is uniformly distributed without being densely packed on the positive electrode active material layer, And the performance of the lithium secondary battery using the same can be improved. In addition, the binder contained in the positive electrode active material layer may be appropriately distributed at the interface between the positive electrode active material layer and the positive electrode collector, so that the positive electrode desorption phenomenon can be suppressed.

Therefore, the method of producing the positive electrode according to the present invention and the positive electrode prepared therefrom can be easily applied to an industry requiring it, particularly, a positive electrode and a lithium secondary battery industry using the same.

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 in an ordinary or dictionary sense and the inventor can properly define the concept of the term to describe its invention in the best possible way It should be construed as meaning and concept consistent with the technical idea of the present invention.

The present invention provides a method of manufacturing a positive electrode having uniformly distributing the positive electrode active material and performing the positive electrode active material coating process at a high speed while increasing the adhesion between the positive electrode active material layer and the positive electrode current collector. At this time, the coating step may include coating the positive electrode active material slurry on one surface of the positive electrode current collector, and drying the positive electrode current collector coated on one surface of the positive electrode active material slurry.

The method of manufacturing an anode according to an embodiment of the present invention includes the steps of (1) preparing a cathode current collector coated with a cathode active material slurry by applying a cathode active material slurry on one surface of a cathode current collector; And drying the cathode current collector coated with the cathode active material slurry (step 2), wherein the cathode active material slurry includes a cathode active material having a first magnetic property, The active material slurry is applied while applying a second magnetic property to the lower surface of the one surface opposite to one surface of the cathode current collector to which the active material slurry is applied, and the first and second magnetic properties are opposite to each other.

The method of manufacturing the positive electrode according to the present invention is not limited to the positive electrode, but may be applied to the negative electrode when necessary.

The step 1 is a step of placing the slurry of the positive electrode active material on the positive electrode current collector and applying the slurry of the positive electrode active material on one surface of the positive electrode current collector.

The positive electrode active material slurry may include additives such as a binder, a conductive material, and a filler to the first magnetic active material having a magnetic property, and may further include a dispersion medium in organic-based mixing.

It is important that the positive electrode active material is uniformly distributed in the positive electrode active material layer in order to have excellent properties such as electrical conductivity of the positive electrode.

The binder is a component that assists in bonding of the positive electrode active material and the conductive material and bonding to the positive electrode collector. In order to improve the adhesion between the positive electrode active material layer and the positive electrode collector in the finally produced positive electrode, the distribution position of the binder is an important factor . That is, as the binder is distributed at a position adjacent to the interface between the positive electrode active material layer and the positive electrode collector, the adhesion of the positive electrode can be excellent.

However, as described above, the positive electrode is manufactured through a coating process in which the positive electrode active material slurry is coated on one surface of the current collector and dried, and when the speed of the application and drying process, particularly, the drying process is high, the positive electrode active material and the binder are evaporated A dispersion medium or the like, and is concentrated on the upper portion of the cathode active material layer or is concentrated at a certain portion, which results in deterioration of the electrical conductivity and the like of the anode and the desorption of the anode. Therefore, it may be important to appropriately distribute the cathode active material and the binder in order to improve the productivity by increasing the speed of the coating process without causing deterioration and detachment of the anode. In the present invention, The above problems can be solved.

Specifically, the manufacturing method according to the present invention includes the step of coating and drying the cathode active material slurry on the anode current collector as described above, and at the time of at least one of the coating and drying, It is possible to appropriately distribute the cathode active material in the cathode active material layer by performing magnetization opposite to the active material. In addition, the binder may move along with the cathode active material, and the binder may be appropriately distributed in the cathode active material layer.

The cathode active material may include a metal component having a first magnetic property. Specifically, the cathode active material may be a lithium iron phosphate-based cathode active material represented by the following general formula (1).

[Chemical Formula 1]

Li _{1 + a} Fe _{1 - x} M _x (PO _{4 -b} ) X _b

In Formula 1,

M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Mn, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn, Y,

X is F, S, N or a combination thereof,

a is -0.5? a? 0.5,

x is 0? x? 0.5,

b is 0? b? 0.1.

Preferably, the lithium iron phosphate-based cathode active material may be LiFePO ₄ , LiFeMnPO ₄ , LiFeMgPO ₄ , LiFeNiPO ₄ , LiFeAlPO ₄ or LiFeCoNiMnPO ₄ , and most preferably LiFePO ₄ .

The binder may be selected from the group consisting of vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HEP), polyvinylidene fluoride, chlorotrifluoroethylene (CFTE), polyacpolyacrylo Polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, But may be one or more selected from the group consisting of ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butylene rubber (SBR) and fluorine rubber. At this time, the binder may be contained in the electrode active material slurry in an amount of 1% by weight to 30% by weight based on the total amount of the cathode active material, but is not limited thereto.

The cathode current collector generally has a thickness of 3 to 500 탆, and is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. Examples of the cathode current collector include copper, stainless steel, aluminum, nickel , Titanium, sintered carbon, or a surface treated with carbon, nickel, titanium or silver on the surface of aluminum or stainless steel, or the like can be used.

The conductive material is not particularly limited as long as it has electrical conductivity without causing side reactions with other elements of the battery. Examples of the conductive material include graphite such as natural graphite and artificial graphite; Carbon black such as carbon black (super-p), acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; And conductive materials such as polyphenylene derivatives can be used. The conductive material may be contained in the electrode active material slurry in an amount of 0.05 wt% to 5 wt% based on the total amount of the cathode active material, but is not limited thereto.

The filler is a component for suppressing the expansion of the anode. The filler is not particularly limited as far as it is a fibrous material without causing any chemical change in the battery. The filler may be an olefin polymer such as polyethylene or polypropylene ; Glass fiber, carbon fiber, or the like.

The solvent is not particularly limited, but may be, for example, isopropyl alcohol, N-methylpyrrolidone (NMP), acetone or the like.

The anode active material slurry may be sprayed or distributed on the cathode current collector, and uniformly dispersed using a doctor blade or the like. can do. In addition, it can be performed by a method such as die casting, comma coating, screen printing and the like.

Step 2 is a step for forming a solid cathode active material layer by applying heat or the like to the cathode current collector coated with the cathode active material slurry to evaporate a dispersion medium (for example, NMP) in the cathode active material slurry. At this time, the solid concentration of the formed cathode active material layer may be 47% to 60%.

The drying may be performed by directly heating the cathode current collector coated with the cathode active material slurry or by applying hot air, and preferably by applying hot air.

Specifically, the drying may be performed at a temperature ranging from 100 ° C to 130 ° C and at a rate of 50 l / min to 150 l / min.

The coating and drying may be performed while applying a second magnetic force to one surface of the cathode current collector opposite to the one surface of the cathode current collector coated with the cathode active material slurry in any one or more of the above steps. The second magnetism may be applied by a moving roll moving the cathode current collector.

The second magnetic property means magnetism opposite to the first magnetic property. That is, the manufacturing method according to the present invention is performed while applying a second magnetic property to the lower portion of the cathode current collector (below the surface opposite to the one surface to which the cathode active material slurry is applied) in at least one of the coating and drying, The positive electrode active material having one magnetic property can be uniformly distributed in the positive electrode active material layer and the binder can be uniformly distributed in the positive electrode active material layer by moving the binder together with the movement of the positive electrode active material, Degradation and desorption phenomena can be suppressed.

Specifically, as described above, the manufacturing method according to the present invention may be performed while applying a second magnetic force to one surface of the cathode current collector opposite to the one surface of the cathode current collector to which the cathode active material slurry is applied in at least one of coating and drying And when the second magnetism is applied in both the application and drying phases, the second magnetism may be applied by the same moving roll or may be applied by different moving rolls.

The moving roll may be 300 mm to 2000 mm in diameter. If the diameter of the moving roll is less than 300 mm, there may be a problem of separation during the coating process (coating and drying) due to a lack of flexibility of the positive electrode collector. If the diameter exceeds 2000 mm, Adjustment may not be easy.

The permanent magnet may be any one of a Ne-Fe-B magnet, an Sm-Co magnet, a neodymium magnet, and the like. Magnets, Fe-Al-Ni-Co magnets, and oxide magnets.

The intensity of the second magnetic force applied by the moving roll may be appropriately adjusted according to the purpose, but it may be adjusted within the range of preferably 15,000 G to 30,000 G. If the intensity of the second magnetic force is less than 15,000 G, the effect on the first magnetic property of the cathode active material may be insufficient and it may be difficult to obtain the desired effect. If the intensity of the second magnetic force exceeds 30,000 G, The cathode active material may not be uniformly distributed, and the cathode current collector may be densely packed or the moving roll may be contaminated. Here, "G" means a unit gauss indicating the intensity of the magnetic force.

Meanwhile, in the manufacturing method according to the present invention, the second magnetic property can be added and the second electric charge can be further applied, if necessary, so that the binder can be positioned closer to the interface of the positive electrode collector. At this time, the second electric charge is performed while applying to the lower surface of one side of the cathode current collector, to which the cathode active material slurry is applied in at least one of coating and drying like the second magnetism. In this case, It may be desirable to include a binder that is electrically charged. The first charge and the second charge mean charge opposite to each other.

The binder having the first charge represents at least one binder such as a binder having a positive charge or a negative charge, and may preferably be a binder having a negative charge. Specifically, it may be at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl pyrrolidone and tetrafluoroethylene. At this time, the binder having the first charge may be contained in the electrode active material slurry in an amount of 1% by weight to 30% by weight based on the total amount of the cathode active material, but is not limited thereto.

The second charge may be applied by a second moving roll, and the second moving roll may be a corona wire or a Teflon roll.

The corona wire is connected to a power supply unit, and the second charge can be drawn by a voltage transmitted from the power supply unit. In this case, the second charge can be controlled according to the first charge as described above, and the charge can be controlled by adjusting the charge amount, and the charge amount can be 1 C (coulomb) to 2 C. The corona wire may have a diameter of 300 nm to 1,000 nm, and the voltage may be adjusted to a range of 0.9 kV to 1.5 kV. At this time, when the voltage is lower than 0.9 kV, the voltage is weak and sufficient charge is not applied, so that the coating speed is lowered and the adhesion force between the electrode current collector and the electrode active material layer may be decreased. When the voltage is higher than 1.5 kV, The above effect is insignificant and the economic efficiency may be lowered.

In addition, the Teflon roll may have two to five Teflon rolls connected thereto, and the second charge may be drawn by rotational friction between the adjacent (adjacent) Tetron rolls.

Further, the present invention provides a positive electrode prepared from the above-mentioned production method.

The positive electrode according to an embodiment of the present invention may be such that the positive electrode active material is uniformly distributed within the positive electrode active material layer or within the positive electrode active material layer within the positive electrode active material layer, And may be uniformly distributed in the vicinity of the whole or in the first half. Accordingly, the adhesion between the positive electrode current collector and the positive electrode active material layer can be excellent, so that the desorption phenomenon can be suppressed and the characteristics such as electric conductivity can be excellent.

In addition, the present invention provides a lithium secondary battery including the positive electrode, the negative electrode, and the separator interposed between the positive electrode and the negative electrode.

The lithium secondary battery according to an embodiment of the present invention includes an anode, a cathode, and a separator interposed between the anode and the cathode, and an electrolyte.

The negative electrode may be prepared by applying a negative electrode active material slurry on at least one side of the negative electrode collector, followed by drying and rolling.

The negative electrode current collector may be the same as or included in the positive electrode current collector.

The negative electrode active material slurry may contain, in addition to the negative electrode active material, an additive such as a binder, a conductive material, and a filler.

The anode active material is not particularly limited and a carbonaceous material, lithium metal, silicon, or tin, which is commonly known in the art and capable of intercalating and deintercalating lithium ions, may be used. Preferably, the carbon material may be used. As the carbon material, both low-crystalline carbon and highly-crystalline carbon may be used. Examples of the low crystalline carbon include soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, kish graphite, pyrolytic carbon, liquid crystal pitch carbon High temperature calcined carbon such as mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar pitch derived cokes.

The additives such as the binder, the conductive material and the filler may be as described above or may be included.

The separator may be an insulating thin film having high ion permeability and mechanical strength, and may have a pore diameter of 0.01 to 10 m and a thickness of 5 to 300 m. As such a separation membrane, a porous polymer membrane such as a porous polymer membrane made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer and an ethylene / methacrylate copolymer may be used alone Or they can be laminated, or a nonwoven fabric made of a conventional porous nonwoven fabric such as a glass fiber having a high melting point, polyethylene terephthalate fiber or the like can be used, but the present invention is not limited thereto.

In addition, the electrolyte may include an organic solvent and a lithium salt commonly used in an electrolyte, and is not particularly limited.

With the lithium salt of the anion is ^{F -, Cl -, I -} , NO 3 -, N (CN) 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 CO 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 CO 2 -, SCN - , and _{(CF 3 CF 2 SO 2)} 2 N - may be at least one member selected from the group consisting of .

Examples of the organic solvent include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, dipropyl carbonate, dimetal sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, vinylene And may be one or more selected from the group consisting of carbonates, sulfolane, gamma-butyrolactone, propylene sulfite and tetrahydrofuran.

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

In order to improve the charge-discharge characteristics and the flame retardant characteristics, the electrolyte may further contain at least one selected from the group consisting of pyridine, triethylphosphate, triethanolamine, cyclic ether, ethylenediamine, glyme, hexaphosphoric triamide, , Sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, aluminum trichloride, . In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage property, a carbon dioxide gas may be further added. FEC (fluoro-ethylene carbonate ), PRS (propene sulfone), FPC (fluoro-propylene carbonate), and the like.

The lithium secondary battery of the present invention can be manufactured by disposing a separator between an anode and a cathode to form an electrode assembly, inserting the electrode assembly into a cylindrical battery case or a prismatic battery case, and then injecting an electrolyte. Alternatively, the electrode assembly may be laminated, impregnated with the electrolyte, and the resultant may be sealed in a battery case.

The battery case used in the present invention may be of any type that is commonly used in the art, and is not limited in its external shape depending on the use of the battery. For example, a cylindrical case, a square type, a pouch type, (coin) type or the like.

The lithium secondary battery according to the present invention can be used not only in a battery cell used as a power source of a small device but also as a unit cell in a middle- or large-sized battery module including a plurality of battery cells. Preferable examples of the above medium and large-sized devices include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric power storage systems, and the like.

Claims (15)

Preparing a cathode current collector coated with a cathode active material slurry by applying a cathode active material slurry on one surface of a cathode current collector; And
And drying the cathode current collector coated with the cathode active material slurry,
Wherein the positive electrode active material slurry includes a first magnetic active material,
The coating and drying are performed while applying a second magnetic force to a lower surface of one surface of the cathode current collector to which the cathode active material slurry is applied,
Wherein the first and second magnetic properties are opposite to each other,
The second magnetic property is applied by a moving roll for moving the cathode current collector,
Wherein the moving roll is a permanent magnet, an electromagnet, or a combination thereof.
delete Claim 1
Wherein the moving roll has a diameter of 300 mm to 2000 mm.
delete The method according to claim 1,
Wherein the permanent magnet is at least one selected from the group consisting of Ne-Fe-B magnet, Sm-Co magnet, Neodymium magnet, Fe-Al-Ni-Co magnet and Oxide magnet .
The method according to claim 1,
Wherein the intensity of the second magnetic field is in the range of 15,000 G to 30,000 G.
The method according to claim 1,
Wherein the cathode active material is a lithium iron phosphate-based cathode active material represented by the following Formula 1:
[Chemical Formula 1]
Li _{1 + a} Fe _{1 - x} M _x (PO _{4 -b} ) X _b
In Formula 1,
M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Mn, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn, Y,
X is F, S, N or a combination thereof,
a is -0.5? a? 0.5,
x is 0? x? 0.5,
b is 0? b? 0.1.
The method of claim 7,
Wherein the lithium iron phosphate-based positive electrode active material is LiFePO ₄ .
The method according to claim 1,
Wherein at least one of the application and the drying is performed while further applying a second charge to a lower surface of one surface of the cathode current collector to which the cathode active material slurry is applied,
Wherein the positive electrode active material comprises a binder having a first charge.
The method of claim 9,
The second charge is applied by the second moving roll,
Wherein the second moving roll is a corona wire or a Teflon roll.
The method of claim 10,
The corona wire is connected to a power supply,
Wherein the corona wire has a second electric charge due to a voltage transmitted from the power supply unit.
The method of claim 10,
The Teflon roll has two to five Teflon rolls connected thereto,
Wherein the Teflon roll has a second charge due to rotational friction between the Teflon rolls connected thereto.
The method of claim 9,
Wherein the binder is at least one of polyvinylidene fluoride, polyvinyl pyrrolidone, and tetrafluoroethylene.
An anode prepared from the process of claim 1.
A lithium secondary battery comprising a cathode, a cathode, and a separator interposed between the anode and the cathode.