KR20150115538A - Current collector for lithium secondary battery and electorde comprising the same - Google Patents

Abstract

The present invention relates to a current collector and an electrode for a secondary battery wherein the current collector includes a coating layer comprising: a conductive substrate; a polynorbornene (PNB)-based polymer on at least one surface of the conductive substrate; a first conductive material; and a first solvent. The current collector of the present invention includes a coating layer comprising the PNB-based polymer on at least one surface of the conductive substrate and thereby it is possible to improve an interfacial adhesion with an electrode active material and possible to reduce contact resistance. In addition, the secondary battery including the current collector is capable of minimizing a release of an active material layer from the current collector in a secondary battery assembly process and at the time of charge and discharge, and capable of further improving performance of the secondary battery due to the low contact resistance.

Description

TECHNICAL FIELD [0001] The present invention relates to a current collector for a lithium secondary battery and an electrode including the same. BACKGROUND OF THE INVENTION [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current collector for a lithium secondary battery and an electrode including the same. More particularly, the present invention relates to a current collector for a lithium secondary battery, , And an electrode comprising the same.

As technology development and demand for mobile devices increase, the demand for secondary batteries that can be recharged and can be miniaturized and increased in capacity is rapidly increasing. In addition, among secondary batteries, lithium secondary batteries having high energy density and voltage are commercialized and widely used.

Among these, nickel-hydrogen (Ni-MH) batteries, lithium (Li) ion batteries and lithium ion (Li-ion) polymer batteries have been developed and used.

In these secondary batteries, most of the bare cells contain an electrode assembly made of an anode, a cathode and a separator in a can made of aluminum or an aluminum alloy, a can is finished with a cap assembly, an electrolyte is injected into the can .

 In the lithium secondary battery, the electrode is often formed by applying a slurry containing an electrode active material to a surface of a current collector made of a metal foil or a metal mesh. The slurry is usually formed by mixing a solvent, a conductive material, an electrode active material, a binder, and the like.

 The electrode of the lithium secondary battery is manufactured by mixing such an active material and a binder component and dispersing the active material in a solvent to form a slurry and applying the slurry to the collector surface to form a mixture layer after drying. However, due to the volume change caused by the reaction with lithium during charging and discharging, the active material is removed from the current collector during continuous charging and discharging, or the resistance increases due to the change of the contact interface between the active materials, And the cycle life is shortened.

The binder imparts not only the active material but also the binding force between the active material and the current collector, and suppresses the volume expansion due to charging and discharging of the battery, thereby having an important influence on the battery characteristics. However, when an excessive amount of polymer is used as a binder in order to reduce the volume change during charging and discharging, it is possible to reduce the desorption of the active material from the current collector, but the electrical resistance of the electrode is increased by the electrical insulating property of the binder, There is a possibility that the capacity may be reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

A first problem to be solved by the present invention is to provide a current collector capable of improving interfacial adhesion with an electrode active material and reducing contact resistance (surface resistance).

A second problem to be solved by the present invention is to provide a secondary battery capable of minimizing detachment of the active material layer from the current collector and improving the performance of the secondary battery during the secondary battery assembling process, .

In order to solve the above-described problems, the present invention provides a semiconductor device comprising: a conductive substrate; And a coating layer containing at least one polynorbornene polymer (PNB) and a first conductive material on at least one side of the conductive base.

In addition, the present invention is characterized in that: the current collector; And an active material layer formed on at least one surface of the current collector.

According to another aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: forming a coating layer on at least one surface of a conductive substrate by coating a coating liquid containing a polynorbornene polymer (PNB), a first conductive material, and a first solvent; And coating the active material slurry on at least one surface of the coating layer to form an active material layer.

Further, the present invention provides a lithium secondary battery including the electrode.

The current collector according to an embodiment of the present invention includes a coating layer containing a polynorbornene-based polymer on at least one surface of the conductive base material, thereby improving the interfacial adhesion with the electrode active material and reducing the contact resistance. In addition, the secondary battery including the current collector can minimize the desorption of the active material layer from the current collector during the secondary battery assembling process and charge / discharge, and can further improve the cycle characteristics of the secondary battery due to low contact resistance.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention and, together with the description of the invention, It should not be construed as limited.
1 is a schematic view showing an electrode including a current collector according to an embodiment of the present invention.

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.

Unless otherwise defined, the term "substituted" refers to an alkyl group having 1 to 20 carbon atoms, a C1 to C20 alkoxy group, a carboxy group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C3 to C20 cycloalkyl group, a C3 A C3 to C20 cycloalkynyl group, a C3 to C20 heterocycloalkyl group, a C3 to C20 heterocycloalkenyl group, a C3 to C20 heterocycloalkynyl group, a C6 to C20 aryl group, and a C2 to C20 heterocycloalkenyl group, C20 < / RTI > heteroaryl group. &Quot; Hetero "means a functional group containing 1-3 heteroatoms selected from the group consisting of N, O, S, P, and Si, unless otherwise defined.

A current collector according to an embodiment of the present invention includes a conductive substrate; And a coating layer containing a polynorbornene (PNB) polymer and a first conductive material on at least one side of the conductive base.

In the current collector according to an embodiment of the present invention, the polynorbornene-based polymer may include a polymer having the following formula:

≪ Formula 1 >

Wherein n is an integer from 1 to 4,

R ₁ represents hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a carboxylate ester group (-COOR ₂ ), a silyl group (-SiR ₃ R ₄ R ₅ ), an alkoxysilyl group (-Si (OR ₆ ) OR ₇ ) (OR ₈ ), a siloxy group (-OSi (R ₉ ) (R ₁₀ ) (R ₁₁ )), a hydroxy and an amine group,

R ₂ to R ₁₁ are the same or different and each represents a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 heterocycloalkyl group, An unsubstituted C6 to C20 aryl group and a substituted or unsubstituted C2 to C20 heteroaryl group.

The polynorbornene-based polymer which is a polymer contained in the coating layer of the current collector can be obtained by three types of polymerization as shown in the following Reaction Scheme 1:

<Reaction Scheme 1>

First, polynorbornene by Ring Opening Methathesis Polymerization (ROMP) contains a double bond, and an ARTON® polymer can be synthesized by a hydrogen-lowering reaction. Second, polynorbornene by vinyl addition polymerization shows high glass transition temperature due to the rigid structure in the main chain of the polymer, and has characteristics of amorphous polymer. Thirdly, the polynorbornene by cationic or radical polymerization can obtain a polynorbornene polymer of low molecular weight.

The polynorbornene-based polymer contained on the current collector according to an embodiment of the present invention is a polynorbornene-based polymer produced by vinyl addition polymerization and contains a multicyclic compound having a high glass transition temperature as a main chain, , Since the vacant lattice sites are relatively large, it can be well mixed with, for example, a carbon-based conductive material, and is excellent in dispersion stability.

Therefore, when the coating layer containing the polynorbornene-based polymer is formed on one surface of the conductive base material, the interface adhesion with the electrode active material can be improved and the contact resistance to the current collector can be reduced. In addition, the secondary battery including the current collector can minimize the desorption of the active material layer from the current collector during the secondary battery assembling process and charge / discharge, and further improve the performance, especially the cycle characteristics, .

The polynorbornene polymer is preferably selected from the group consisting of polynorbornene, poly (methyl norbornene), poly (ethyl norbornene), poly (butyl norbornene), poly (butyl norbornene) (Norbornene carboxylic acid methyl ester), poly (norbornene carboxylic acid n-butyl ester), poly (trimethylsilyl norbornene), poly (triethoxysilyl norbornene), poly Poly (ethylhydroxy norbornene), poly (ethylhydroxy norbornene), poly (hydroxy norbornene), poly (methylhydroxy norbornene) (Triarylamine norbornene), or a mixture of two or more thereof. The polynorbornene-based polymer may include, for example, methylnorbornene, butylnorbornene, and hydroxyethylnorbornene Were synthesized by mixing an appropriate amount of poly Novo can nenil.

In the current collector according to an embodiment of the present invention, the polynorbornene-based polymer preferably has a weight average molecular weight (Mw, GPC) of 5,000 to 300,000, preferably 50,000 to 200,000.

When the polynorbornene-based polymer has a weight average molecular weight of less than 5,000, the effect of improving the interface adhesion between the current collector and the electrode active material may be insignificant. When the polynorbornene polymer is more than 300,000, dispersion stability of the conductive material may be deteriorated.

According to an embodiment of the present invention, organic polymers or water-based polymers commonly used in addition to the polynorbornene-based polymer may be further included.

The organic polymer is a polymer dissolved or dispersed in an organic solvent, particularly N-methyl pyrrolidone (NMP), and the aqueous polymer may be a polymer containing water as a solvent or a dispersion medium. Non-limiting examples of the organic polymer include polyvinylidene fluoride (PVDF), polyimide, polyamideimide, and combinations thereof. Non-limiting examples of the water-based polymer include styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber or combinations thereof.

The first conductive material included in the coating layer of the current collector according to an embodiment of the present invention is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery. The first conductive material is not particularly limited as long as it is compatible with the polynorbornene polymer Based conductive material may be preferable. For example, the first conductive material may include any one selected from the group consisting of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, and carbon fiber, or a mixture of two or more thereof.

According to one embodiment of the present invention, in the coating layer, the polynorbornene-based polymer and the first conductive material are preferably contained in an amount of 1: 0.2 to 1: 1 by weight. In this case, The interface adhesion with the active material can be improved and the contact resistance to the current collector can be reduced.

The conductive base material may include any one selected from the group consisting of aluminum, copper, stainless steel, nickel, titanium, sintered carbon, and aluminum-cadmium alloy or a mixed base material of two or more thereof.

In the current collector according to an embodiment of the present invention, the thickness of the coating layer included in the conductive base material is preferably 500 nm to 5 占 퐉, preferably 800 nm to 3 占 퐉, To about 5% to about 30% of the thickness of the substrate.

The contact resistance (surface resistance) of the current collector may be 0.1 to 10 mΩ / sq, preferably 0.5 to 5 mΩ / sq based on the thickness of the conductive base material of 10 μm to 30 μm. In one embodiment of the present invention The current collector according to the present invention includes the coating layer on the conductive substrate so that the surface resistance can be lowered to about 20% to 90% as compared with the case where the active material layer is coated directly on the conductive substrate by uniformly connecting the active material with the substrate.

Also, according to an embodiment of the present invention, the current collector, And an active material layer formed on at least one surface of the current collector.

1, an electrode 100 according to an exemplary embodiment of the present invention includes a conductive base 110 such as aluminum or the like, A current collector 150 including a coating layer 140 on at least one side of the conductive base 110; And the active material layer 170 may be formed on at least one surface of the current collector 150. The coating layer 140 includes a polynorbornene polymer 130 and a first conductive material 120. The active material layer 170 includes an electrode active material 160, a second conductive material 125, and a binder 135 &lt; / RTI &gt;

An electrode according to an embodiment of the present invention may be formed by using a current collector including a coating layer containing a polynorbornene polymer as a conductive base material and not directly forming an active material layer on a conductive base material such as aluminum, By forming the layer, the interfacial adhesion between the current collector and the electrode active material can be improved. In addition, it is possible to minimize the desorption of the active material layer from the current collector during the secondary battery assembling process and the charge / discharge cycle, and further improve the performance of the secondary battery due to the low contact resistance.

The ratio of the thickness of the coating layer to the thickness of the active material layer of the current collector is preferably from 1:10 to 50. In this case, the interface adhesion between the current collector and the electrode active material and the conductivity can be further improved.

According to another embodiment of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a coating layer on at least one surface of a conductive substrate by coating a coating liquid containing a polynorbornene polymer (PNB), a first conductive material, i); And coating the active material slurry on at least one surface of the coating layer to form an active material layer (step ii).

In the step i), a coating method capable of forming a coating layer on a conductive substrate may be a conventional coating method known in the art, for example, a die coating, a roll coating or a dip ) Coating or the like can be used. In addition, a Meyer bar can be used for uniform coating.

The step i) may further include a step of drying at 80 ° C to 150 ° C after coating, and after the drying is sufficiently performed, an active material layer may be formed on the coating layer (step ii).

The first solvent may be used without limitation as long as it can dissolve the polynorbornene polymer. For example, water, any one selected from the group consisting of dimethylformamide (DMF), dimethylacetamide, dimethyl sulfoxide (DMSO), alcohol, acetone and N-methylpyrrolidone (NMP) Mixed solvents of more than two kinds can be used.

The polynorbornene-based polymer may be contained in an amount of 5 to 30 parts by weight based on 100 parts by weight of the solvent. When the amount of the polynorbornene polymer is less than 5 parts by weight, the effect of improving the interface adhesion between the current collector and the electrode active material may be insignificant. When the amount is more than 30 parts by weight, the distribution of the conductive material becomes uneven due to an excessive amount of polymer, In this case, a channel through which current can flow in the electrode is not locally formed, so that the contact resistance of the current collector may increase.

The first conductive material may be included in an amount of 2 to 30 parts by weight based on 100 parts by weight of the solvent.

According to an embodiment of the present invention, the current collector can be used for a positive electrode, a negative electrode, or a positive electrode and a negative electrode, and preferably used as a current collector for a positive electrode is more effective in lowering the overall resistance of the lithium secondary battery Lt; / RTI &gt;

According to an embodiment of the present invention, when the current collector is applied to a cathode, the cathode active material layer is a cathode active material commonly used in the art, including a manganese-based spinel active material, a lithium metal oxide, . Further, the lithium metal oxide may be selected from the group consisting of a lithium-manganese-based oxide, a lithium-nickel-manganese-based oxide, a lithium-manganese-cobalt oxide, and a lithium-nickel-manganese-cobalt oxide, is _{LiCoO 2, LiNiO 2, LiMnO 2} , LiMn 2 O 4, Li (Ni a Co b Mn c) O 2 ( where, 0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1), LiNi 1 - Y Co Y O 2, LiCo 1-Y Mn Y O 2, LiNi 1 - Y Mn Y O 2 ( here, 0≤Y <1), Li ( Ni a Co b _{Mn c) O 4 (0 <} a <2, 0 <b <2, 0 <c <2, a + b + c = 2), LiMn 2 - z Ni z O 4, LiMn 2 -z Co z O 4 (Where 0 &lt; Z &lt; 2).

According to another embodiment of the present invention, when the current collector is applied to a negative electrode, the negative active material layer may be formed of a carbonaceous anode active material such as crystalline carbon, amorphous carbon, or carbon composite, And may include graphite carbon such as natural graphite and artificial graphite, preferably crystalline carbon. Also, a Si-based negative active material containing Si may be included. Specifically, for example, Si alone; A Si-C composite (Si-C composite) formed by mechanically alloying Si and a carbonaceous material; A composite in which Si and a metal are mechanically alloyed; Carbon-Si nanocomposite; Si oxide (SiOx (1? X? 2), and Si or Si oxide coated with carbon, or a mixture of two or more thereof. In the Si-C composite, Natural graphite, artificial graphite, MCMB (MesoCarbon MicroBead), carbon fiber and carbon black, or a mixture of two or more thereof.

In the step ii), the active material slurry may be prepared by mixing the active material, the second conductive material, and the binder with the second solvent.

The second conductive material is typically added in an amount of 1 to 20% by weight based on the total weight of the active material slurry containing the active material. The second conductive material is not particularly limited as long as it has electrical conductivity without causing any chemical change in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, 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 oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component that assists in bonding of the active material to the second conductive material and bonding to the current collector. The binder is usually added in an amount of 1 to 20 wt% based on the total weight of the active material slurry containing the active material. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene And examples thereof include ethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber and various copolymers thereof.

In addition, preferred examples of the second solvent include dimethyl sulfoxide (DMSO), alcohol, N-methylpyrrolidone (NMP), acetone or water, and may be removed during drying.

In addition, the present invention provides a lithium secondary battery including the electrode.

The electrode may be a positive electrode or a negative electrode. When the negative electrode including the positive electrode active material and the negative electrode including the negative electrode active material are manufactured, a separator and an electrolyte solution interposed between the positive electrode and the negative electrode, A lithium secondary battery can be manufactured.

As the separator, a conventional porous polymer film conventionally used as a separator, for example, 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 The porous polymer film made of a polymer may be used alone or in a laminated form, 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 may be used. no.

A separator is disposed between the positive electrode and the negative electrode to form an electrode assembly. The electrode assembly is inserted into a cylindrical battery case or a prismatic battery case, and then an electrolyte is injected to complete the secondary battery. Alternatively, the electrode assembly is laminated, then impregnated with the electrolytic solution, and the resulting product is sealed in a battery case to complete the lithium secondary battery.

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.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Example

Example 1: Preparation of lithium secondary battery

&Lt; Production of positive electrode current collector &

Step 1: Preparation of coating liquid composition

, 10 parts by weight of PNB (methyl norbornene: butyl norbornene: hydroxyethyl norbornene = 80: 15: 5 mol% synthesized polynorbornene) having a weight average molecular weight of 100,000 was added to 85 parts by weight of N-methyl pyrrolidone (NMP) , And 5 parts by weight of carbon black (Timcal super P) was added to the mixed solution. The polynorbornene-based polymer and the first conductive material were uniformly dispersed using a planetary mixer (revolution 2000 rpm, rotation 800 rpm) to prepare a coating liquid composition.

Step 2: Production of current collector

The coating liquid composition prepared in the above step 1 was coated on an aluminum foil (thickness: 15 탆) as a conductive substrate using a Mayer bar, and then dried at 130 캜 for 5 minutes. The thickness of the coating layer was about 2 mu m.

&Lt; Preparation of positive electrode &

On the coating layer of the cathode current collector prepared in the step 2, 92 wt% of LiNi _0.6 Mn _0.2 Co _0.2 O ₂ was used as a cathode active material, 4 wt% of super-p was used as a second conductive material and 4 wt% of polyvinylidene fluoride was used as a binder. Was coated on the positive electrode active material slurry, dried, and rolled to produce a positive electrode.

&Lt; Preparation of negative electrode &

96.3% by weight of carbon powder, 1.0% by weight of super-p as a second conductive material, 1.5% by weight and 1.2% by weight of SBR and carboxymethyl cellulose (CMC) as a binder were added to the NMP as a negative electrode active material, Slurry. The negative electrode active material slurry was applied to a copper (Cu) thin film as an anode current collector having a thickness of 10 mu m, dried, and rolled to produce a negative electrode.

&Lt; Preparation of non-aqueous electrolytic solution &

LiPF ₆ was added to a nonaqueous electrolyte solvent prepared by mixing ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) as electrolytes in a volume ratio of 1: 1: 1 to prepare a 1 M LiPF ₆ non- .

&Lt; Preparation of lithium secondary battery &

The prepared positive electrode and negative electrode were sandwiched between a polyethylene separator and a polypropylene mixed separator, followed by preparing a polymer type battery by a conventional method, and then injecting the prepared non-aqueous electrolyte solution to complete the production of a lithium secondary battery.

Example 2

Except that 10 parts by weight of PNB having a weight average molecular weight of 90,000 (polynorbornene synthesized with 80: 16: 4 mol% of methyl norbornene: butyl norbornene: triethoxysilyl norbornene) , And a lithium secondary battery was produced in the same manner as in Example 1.

Comparative Example 1

A lithium secondary battery was produced in the same manner as in Example 1, except that, in the production of the positive electrode, a positive electrode current collector including the coating layer of Example 1 was used instead of a current collector made of only an aluminum thin film.

Experimental Example

<Surface resistance>

The surface resistivities of the positive electrodes obtained in Examples 1 and 2 and Comparative Example 1 were measured by a 4 probe CMT-SERIES (Changmin Tech) equipment.

&Lt; Peel test >

The positive electrode current collector obtained in Examples 1 and 2 and Comparative Example 1 was fixed to a slide glass, and the force applied when the current collector was stripped at 180 was measured.

&Lt; Test of characteristics of electrolyte solution >

The positive electrodes obtained in Examples 1 and 2 and Comparative Example 1 were immersed in an electrolytic solution at 60 占 폚 for 5 days, and then the expansion and peeling of the positive electrode were visually observed to confirm that the resistance characteristics were maintained.

<Cycle characteristics>

To evaluate the life characteristics of the lithium secondary batteries obtained in Examples 1 and 2 and Comparative Example 1, electrochemical evaluation experiments were performed as follows.

The lithium secondary batteries obtained in Examples 1 and 2 and Comparative Example 1 were charged at a constant current (CC) of 4.1 C at a temperature of 45 DEG C to 0.15 C, and then charged at a constant voltage (CV) of 4.15 V, The first charging was performed until mAh was reached. Thereafter, the battery was allowed to stand for 20 minutes, discharged at a constant current of 1.0 C until it reached 2.5 V, and then repeatedly cycled through 60 cycles. The cycle capacity was measured as a percentage by comparing the capacity after 60 cycles to the initial capacity. The results are shown in Table 1 below.

Experimental Example Example 1 Example 2 Comparative Example 1 Surface resistance (mΩ / sq) 0.244 0.262 0.706 Peel test (gf / cm) 30.6 32.3 21.2 Characteristics of electrolyte Good Good Good Cycle characteristics (%) 96 95 91

As can be seen from the above Table 1, when the current collector including the coating layer containing the polynorbornene-based polymer and the conductive material is used as the aluminum foil as the conductive base material as in Examples 1 and 2, It was found that the surface resistance was reduced by three times or more as compared with Comparative Example 1 using only the collector. This means that the active material and the substrate are uniformly connected to each other by including the coating layer in the conductive base material, thereby improving the interfacial adhesion with the active material, thereby reducing the surface resistance compared to the case where the active material layer is directly coated on the conductive base material .

In the case of the fill test, Examples 1 and 2 were increased by about 50% or more as compared with Comparative Example 1. As a result, it can be predicted that the separation of the active material layer from the current collector can be minimized during the secondary battery assembling process and charging / discharging.

It is also confirmed that the cycle characteristics of the lithium secondary batteries of Examples 1 and 2 are improved by about 5% or more as compared with the lithium secondary batteries of Comparative Example 1.

100: electrode
110: conductive substrate
120: first conductive material 125: second conductive material
130: Polynorbornene-based polymer
135: binder
140: Coating layer
150: The whole house
160: electrode active material
170: active material layer

Claims (19)

Conductive substrates; And a coating layer containing at least one polynorbornene-based polymer (PNB) and a first conductive material on at least one side of the conductive base.
The method according to claim 1,
Wherein the polynorbornene-based polymer comprises a polymer of the following formula (1): < EMI ID =
&Lt; Formula 1 &gt;

Wherein n is an integer from 1 to 4,
R ₁ represents hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a carboxylate ester group (-COOR ₂ ), a silyl group (-SiR ₃ R ₄ R ₅ ), an alkoxysilyl group (-Si (OR ₆ ) OR ₇ ) (OR ₈ ), a siloxy group (-OSi (R ₉ ) (R ₁₀ ) (R ₁₁ )), a hydroxy and an amine group,
R ₂ to R ₁₁ are the same or different and each represents a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C3 to C20 heterocycloalkyl group, An unsubstituted C6 to C20 aryl group and a substituted or unsubstituted C2 to C20 heteroaryl group.
3. The method of claim 2,
The polynorbornene-based polymer may be at least one selected from the group consisting of polynorbornene, poly (methyl norbornene), poly (ethyl norbornene), poly (butyl norbornene), poly (hexyl norbornene), poly (norbornenecarboxylic acid methyl ester) (Norbornenecarboxylic acid n-butyl ester), poly (trimethylsilyl norbornene), poly (triethoxysilyl norbornene), poly (trimethylsiloxy norbornene), poly (hydroxy norbornene) (Trihydroxy norbornene), poly (ethylhydroxy norbornene), poly (ethyl norbornene), poly (ethyl norbornene), poly Or a mixture of two or more of them.
The method according to claim 1,
Wherein the polynorbornene-based polymer has a weight average molecular weight (Mw) of 5,000 to 300,000.
The method according to claim 1,
Wherein the first conductive material comprises any one selected from the group consisting of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, and carbon fiber, or a mixture of two or more thereof.
The method according to claim 1,
Wherein the polynorbornene-based polymer and the first conductive material are contained in an amount of 1: 0.2 to 1: 1 by weight.
The method according to claim 1,
Wherein the thickness of the coating layer is 500 nm to 5 占 퐉.
The method according to claim 1,
Wherein the current collector has a contact resistance (surface resistance) of 0.1 to 10 m? / Sq based on the thickness of the conductive base of 10 占 퐉 to 30 占 퐉.
The method according to claim 1,
Wherein the conductive base material comprises any one selected from the group consisting of aluminum, copper, stainless steel, nickel, titanium, sintered carbon, and aluminum-cadmium alloy or a mixed material of two or more thereof.
The collector of claim 1; And an active material layer formed on at least one side of the current collector.
11. The method of claim 10,
Wherein the ratio of the thickness of the coating layer to the thickness of the active material layer of the current collector is 1:10 to 50.
11. The method of claim 10,
Wherein the electrode is an anode.
Forming a coating layer on at least one surface of a conductive substrate by coating a coating liquid containing a polynorbornene (PNB) polymer, a first conductive material, and a first solvent; And
And coating the active material slurry on at least one surface of the coating layer to form an active material layer.
14. The method of claim 13,
Wherein the coating is a die coating, a roll coating, a dip coating or a MAYER BAR coating.
14. The method of claim 13,
And drying the coated film at a temperature of 80 ° C to 150 ° C after the coating.
14. The method of claim 13,
The first solvent may be any one selected from the group consisting of water, dimethylformamide (DMF), dimethylacetamide, dimethyl sulfoxide (DMSO), alcohol, acetone and N-methylpyrrolidone (NMP) And a mixture of two or more thereof.
14. The method of claim 13,
Wherein the polynorbornene-based polymer is contained in an amount of 5 to 30 parts by weight based on 100 parts by weight of the first solvent.
14. The method of claim 13,
Wherein the first conductive material is contained in an amount of 2 to 30 parts by weight based on 100 parts by weight of the first solvent.
A lithium secondary battery comprising the electrode of claim 10.

Images