KR20170090720A - Electrode for lithium secondary battery and lithium secondary battery indluding the same - Google Patents

Abstract

The present invention relates to an electrode for a lithium secondary battery to reduce resistance of the battery by preventing a binder from moving to the interface of an active material layer, and to a lithium secondary battery including the same. The electrode for a lithium secondary battery comprises: a current collector; and an electrode active material layer formed on one surface of the current collector and including an electrode active material, a conductor and a binder. The conductor comprises a magnetic conductor. The conductor additionally comprises organic particles attached to the surface thereof.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode for a lithium secondary battery and a lithium secondary battery including the electrode,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery electrode and a lithium secondary battery including the same, and more particularly, to a lithium secondary battery having a high capacity characteristic and a lithium secondary battery including the same.

Recently, interest in energy storage technology is increasing. As cell phones, camcorders, notebook PCs, and even electric vehicles' energy are being expanded, efforts are being made to research and develop batteries. BACKGROUND ART Electrochemical devices have been attracting the most attention in this respect. Especially in recent years, with the trend toward miniaturization and light weight of electronic devices, the development of secondary batteries as a battery which can be charged and discharged with small size and high capacity has become a focus of attention.

BACKGROUND OF THE INVENTION [0002] Electrochemical devices have been developed by continuous research as electrode active materials whose various performances, particularly those with significantly improved power. Among the currently applied secondary batteries, the lithium secondary batteries developed in the early 1990's are attracting attention because they have higher operating voltage and higher energy density than conventional batteries such as Ni-MH.

The lithium secondary battery includes a positive electrode, a negative electrode, and an electrolyte. The lithium secondary battery includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode, the negative electrode, and the electrolytic solution transfer lithium ions from the positive electrode active material through the negative electrode active material, Charge / discharge can be performed.

As technology development and demand for mobile devices increase, the demand for secondary batteries as energy sources is rapidly increasing. Among these secondary batteries, a lithium secondary battery having a high energy density and voltage, a long cycle life, and a low discharge rate is commercially available and widely used. In addition, as interest in environmental issues grows, the market for high-capacity battery-use devices such as electric vehicles and hybrid electric vehicles, which can replace fossil-fueled vehicles such as gasoline vehicles and diesel vehicles, There is a demand for designing a high-capacity electrode for manufacturing a lithium secondary battery having high energy density, high output and high discharge voltage as a power source of these devices.

In order to design a high-capacity electrode, an amount of active material is increased, and a high-loading electrode having a large electrode thickness is attempted. However, in such an electrode, the binder moves to the interface of the active material layer during the drying process after application of the active material, There is a problem that the resistance of the battery increases as the number of binders distributed in the battery increases.

SUMMARY OF THE INVENTION The present invention provides a lithium secondary battery electrode capable of reducing the resistance of a battery by preventing the binder from moving to the interface of the active material layer in a high loading electrode and a lithium secondary battery comprising the electrode will be.

According to an aspect of the present invention, there is provided a current collector comprising: a current collector; And an electrode active material layer formed on one surface of the current collector and including an electrode active material, a conductive material, and an organic binder, wherein the conductive material includes a magnetic conductive material, The electrode for a lithium secondary battery is further characterized in that the electrode further comprises organic particles attached to the electrode.

Preferably, the magnetic conductive material may be at least one selected from the group consisting of iron, nickel, and cobalt, or an alloy thereof.

Preferably, the organic particles may have a functional group.

Preferably, the organic binder may have a functional group.

Preferably, the functional group is a carboxyl group (-COOH), a hydroxyl group (-OH), an ester group (-COOR, wherein R is an alkyl group having 1 to 10 carbon atoms, a phenyl group or a benzyl group) NH ₂ ) and a thiol group (-SH).

Preferably, the magnetic conductive material may be included in an amount of 0.1 to 20% by weight.

Preferably, the magnetic conductive material may have a particle size of 0.01 to 10 mu m.

Preferably, the organic binder is selected from the group consisting of carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene- (Meth) acrylic acid and its salts, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, poly (vinylidene chloride), poly (Meth) acrylic acid and a (meth) acrylic acid alkyl ester, and copolymers of these (meth) acrylic acid and a (meth) acrylic acid alkyl ester. And the like.

Preferably, the thickness of the electrode active material layer may be 70 占 퐉 or more.

Preferably, the loading amount of the electrode active material layer is 500 mg / 25 cm ^{2 or} more.

According to another aspect of the present invention, And an electrode active material layer formed on one surface of the current collector, the electrode active material layer including an electrode active material, a conductive material, and an organic binder, wherein the conductive material includes a magnetic conductive material, There is provided an electrode for a lithium secondary battery, which has protrusions on a surface thereof.

According to another aspect of the present invention, there is provided a lithium secondary battery including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the positive electrode or the negative electrode is the above- / RTI >

According to another aspect of the present invention, there is provided a method of manufacturing an electrode slurry, comprising: preparing an electrode slurry including an electrode active material, a magnetic conductive material, and an organic binder; Applying the electrode slurry to one surface of the current collector; Drying the electrode slurry applied on the current collector; And applying a magnetic field to one surface of the current collector to which the electrode slurry is not applied and simultaneously drying the slurry. The present invention also provides a method of manufacturing an electrode for a lithium secondary battery.

The electrode for a lithium secondary battery according to one aspect of the present invention can prevent the binder from moving to the interface of the active material layer, thereby reducing the resistance of the battery.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and together with the description of the invention serve to further the understanding of the technical idea of the invention, It should not be construed as limited.
1 is a cross-sectional view schematically showing a conventional high loading electrode.
2 is a cross-sectional view schematically illustrating an electrode according to an embodiment of the present invention.

The terms used in the specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may properly define the concept of a term to describe its invention in its best possible way And should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention. Therefore, the constitution shown in the embodiments described herein is the most preferable embodiment of the present invention and does not represent all the technical ideas of the present invention, so that various equivalents It should be understood that water and variations may be present.

1 is a cross-sectional view schematically showing a conventional high loading electrode. 1, the electrode 100 for a lithium secondary battery according to the related art has a structure in which the thickness of the active material layer 20 including the conductive material 21 and the binder 22 is formed on one surface of the current collector 10, However, in this case, there is a problem that the resistance of the battery increases as the binder 22 moves to the interface of the active material layer during the manufacturing process of the electrode.

2 is a cross-sectional view schematically illustrating an electrode according to an embodiment of the present invention. 2, a magnetic field is applied to the magnetic element 200 on one side of the current collector 10 to which the electrode slurry is not applied, using the magnetic conductive material 21 having affinity with the binder 22 The magnetic conductive material 21 having affinity with the binder 22 moves together with the binder 22 to move the binder 22 distributed at the interface of the active material layer 20 toward the surface of the current collector 10 .

An electrode for a lithium secondary battery according to an aspect of the present invention includes: a current collector; And an electrode active material layer formed on one surface of the current collector and including an electrode active material, a conductive material, and an organic binder, wherein the conductive material includes a magnetic conductive material, Lt; RTI ID = 0.0 > and / or < / RTI >

When the magnetic field is applied, the organic binder distributed at the interface of the active material layer can be moved toward the surface of the current collector, because the conductive material includes the organic particles attached to the surface.

The conductive material may be carbon black, graphite, carbon fiber, carbon nanotube, metal powder, conductive metal oxide, organic conductive material, etc. The magnetic conductive material may be selected from the group consisting of iron, nickel and cobalt Or more, or an alloy thereof.

The organic particles or the organic binder may have a functional group. By having a functional group, the affinity between the conductive material having the organic particles attached thereto and the organic binder can be further improved, and more organic binder distributed at the interface of the active material layer can be moved toward the surface of the current collector.

The functional group is capable of providing an affinity between an organic binder and an organic particle. Examples of the functional group include a carboxyl group (-COOH), a hydroxyl group (-OH), an ester group (-COOR, wherein R is alkyl having 1 to 10 carbon atoms , A phenyl group, or a benzyl group), an amine group (-NH2), and a thiol group (-SH).

The magnetic conductive material may be contained in an amount of 0.1 to 20% by weight, and may have a particle size of 0.01 to 10 탆.

The binder may be selected from the group consisting of carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, polybutadiene, (Meth) acrylic acid and salts thereof, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, polyvinylpyridine, chlorosulfur, polyvinylpyrrolidone, A copolymer of propylene and an olefin having 2 to 8 carbon atoms, a copolymer of a (meth) acrylic acid and a (meth) acrylic acid alkyl ester, and a combination thereof, which is selected from the group consisting of polyethylene terephthalate, polyethylene, latex, polyester resin, acrylic resin, phenol resin, One can be included.

The binder may be included in an amount of 0.5 to 10% by weight.

The thickness of the electrode active material layer may be 70 μm or more, or the loading amount of the electrode active material layer may be 500 mg / 25 cm ^{2 or} more. In the lithium secondary battery, in order to increase the energy density, a high loading electrode may be used, and the active material layer may be thickened or the loading amount may be increased to manufacture a high loading electrode. The electrode according to one aspect of the present invention can further reduce the resistance of the electrode at the high loading electrode.

The current collector may be a positive current collector or a negative current collector.

The cathode current collector generally has a thickness of 10 to 500 [mu] m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

The negative electrode current collector generally has a thickness of 10 to 500 [mu] m. Such an anode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

The positive electrode active material may be a positive electrode active material or a negative electrode active material.

The cathode active material may be a lithium-containing oxide, and a lithium-containing transition metal oxide may be preferably used. For example, the lithium-containing transition metal _{oxides, Li x CoO 2 (0.5 <} x <1.3), Li x NiO 2 (0.5 <x <1.3), Li x MnO 2 (0.5 <x <1.3), Li x _{Mn 2 O 4 (0.5 <x} <1.3), Li x (Ni a Co b Mn c) O2 (0.5 <x <1.3, 0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1), Li x Ni 1-y Co y O 2 (0.5 <x <1.3, 0 <y <1), Li x Co 1 - y Mn y O 2 (0.5 <x <1.3, 0≤ y <1), Li _x Ni _{1 -y} Mn _y O ₂ (0.5 <x <1.3, 0≤y <1), Li _x (Ni _a Co _b Mn _c ) O 4 <2, 0 <b <2 , 0 <c <2, a + b + c = 2), Li x Mn 2 - z Ni z O4 (0.5 <x <1.3, 0 <z <2), Li x Mn _{2 - z Co z O 4 (} 0.5 <x <1.3, 0 <z <2), Li x CoPO 4 (0.5 <x <1.3) and Li _x FePO ₄ is selected from the group consisting of (0.5 <x <1.3) Or a mixture of two or more of them, and the lithium-containing transition metal oxide may be coated with a metal such as aluminum (Al) or a metal oxide. In addition to the lithium-containing transition metal oxide, sulfide, selenide and halide may also be used.

The negative electrode active material may be a lithium metal, a carbonaceous material, a metal compound, or a mixture thereof, from which lithium ions can be occluded and released.

Concretely, as the carbon material, both low-crystalline carbon and highly-crystalline carbon may be used. Examples of low crystalline carbon are soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, kishgraphite, pyrolytic carbon, liquid crystal pitch carbon fiber mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches, and petroleum or coal tar pitch derived cokes.

Examples of the metal compound include metal elements such as Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, Mg, , And the like. These metal compounds can be used in any form such as a single body, an alloy, an oxide (TiO ₂ , SnO _2, etc.), a nitride, a sulfide, a boride and an alloy with lithium, but an alloy with a single body, alloy, It can be increased in capacity. Among them, it may contain at least one element selected from Si, Ge and Sn, and it may further increase the capacity of the battery including at least one element selected from Si and Sn.

According to another aspect of the present invention, there is provided an electrode for a lithium secondary battery, comprising: a current collector; And an electrode active material layer formed on one surface of the current collector, the electrode active material layer including an electrode active material, a conductive material, and a binder, wherein the conductive material includes a magnetic conductive material, As shown in Fig. The magnetic conductive material has protrusions on the surface thereof, so that the affinity with the binder is improved by the protrusions, and the binder distributed at the interface of the active material layer can be moved toward the surface of the current collector by applying magnetic force during the production of the electrode.

According to an aspect of the present invention, there is also provided a lithium secondary battery including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the positive electrode or the negative electrode is the above-described electrode.

The separation membrane may be a porous polymer substrate. Examples of the porous polymer substrate include, but are not limited to, polyethylene, polypropylene, polyethyleneterephthalate, polybutyleneterephthalate, polyester, Polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamide, and the like. Polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene oxide, cyclic olefin copolymer, polyphenylenesulfide and polyethylene naphthalene (also referred to as &quot; polyethylenenaphthalene &lt; / RTI &gt; A polymer membrane formed of any one of the polymers or a mixture of two or more thereof, or a multiple membrane thereof, woven fabric, or nonwoven fabric.

The thickness of the porous polymer substrate is not particularly limited, but may be about 5 to about 50 탆. The pore size and porosity present in the porous polymer substrate are also not particularly limited, but may be about 0.01 to about 50 탆 each, and about 10 to about 95%.

According to an aspect of the present invention, there is provided a method of manufacturing an electrode for a lithium secondary battery, comprising: preparing an electrode slurry including an electrode active material, a magnetic conductive material, and a binder; Applying the electrode slurry to one surface of the current collector; Drying the electrode slurry applied on the current collector; And applying a magnetic field to one surface of the current collector to which the electrode slurry is not applied and drying the slurry.

The above-mentioned magnetic conductive material can be used for the magnetic conductive material.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

10: The whole house
20: active material layer
21: Conductive material
22: Binder
100: electrode
200: magnetic device

Claims (13)

Collecting house; And an electrode active material layer formed on one surface of the current collector, the electrode active material layer including an electrode active material, a conductive material, and an organic binder,
Wherein the conductive material comprises a magnetic conductive material,
Wherein the conductive material further comprises organic particles adhered to the surface of the conductive material. The method according to claim 1,
Wherein the magnetic conductive material is at least one selected from the group consisting of iron, nickel, and cobalt, or an alloy thereof. The method according to claim 1,
Wherein the organic particles have a functional group. The method according to claim 1,
Wherein the organic binder has a functional group. 5. The method according to any one of claims 3 to 4,
The functional group may be a carboxyl group (-COOH), a hydroxyl group (-OH), an ester group (-COOR, wherein R is an alkyl, phenyl or benzyl group having 1 to 10 carbon atoms), an amine group (-NH ₂ ) And a thiol group (-SH). [5] The electrode for a lithium secondary battery according to claim 1, The method according to claim 1,
Wherein the magnetic conductive material is contained in an amount of 0.1 to 20% by weight. The method according to claim 1,
Wherein the magnetic conductive material has a particle size of 0.01 to 10 mu m. The method according to claim 1,
The organic binder may be selected from the group consisting of carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, polybutadiene, butyl (Meth) acrylic acid and salts thereof, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, polyvinylpyridine, chloroform, A copolymer of propylene and an olefin having 2 to 8 carbon atoms, a copolymer of a (meth) acrylic acid and a (meth) acrylic acid alkyl ester, and a combination thereof, is selected from the group consisting of a sulfonated polyethylene, a latex, a polyester resin, an acrylic resin, a phenol resin, Wherein the first electrode and the second electrode are electrically connected to each other. The method according to claim 1,
Wherein the electrode active material layer has a thickness of 70 mu m or more. The method according to claim 1,
Wherein the loading amount of the electrode active material layer is 500 mg / 25 cm &lt; ² &gt; or more. Collecting house; And an electrode active material layer formed on one surface of the current collector, the electrode active material layer including an electrode active material, a conductive material, and an organic binder,
Wherein the conductive material comprises a magnetic conductive material,
Wherein the magnetic conductive material has protrusions on the surface thereof. A lithium secondary battery comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode,
Wherein the positive electrode or the negative electrode is an electrode according to any one of claims 1 to 11. Preparing an electrode slurry including an electrode active material, a magnetic conductive material, and an organic binder;
Applying the electrode slurry to one surface of the current collector;
Drying the electrode slurry applied on the current collector; And
Applying a magnetic field to one surface of the current collector to which the electrode slurry is not applied and drying the slurry.

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