KR101120437B1 - Negative Electrode Coated with Conductive Polymer in Uniform Pattern and Secondary Battery Containing the Same - Google Patents

Abstract

The present invention is a negative electrode that is in close contact with a negative electrode mixture composed of a negative electrode active material, a binder and a conductive material coated on the current collector, to improve the binding strength and electrical conductivity of the negative electrode mixture to the current collector, It provides a negative electrode for a secondary battery, characterized in that the thin coating of the conductive polymer in a uniform pattern on the whole, and is applied by applying a negative electrode mixture on the coating layer, the negative electrode maintains the electrical conductivity between the current collector and the mixture At the same time, there is an effect of improving the bonding strength of the negative electrode mixture to the current collector.

Description

Negative Electrode Coated with Conductive Polymer in Uniform Pattern and Secondary Battery Containing the Same}

1 is a schematic diagram of a manufacturing process for forming a polymer layer and a mixture layer in the negative electrode according to an embodiment of the present invention;

2A-2C are plan views of release paper that may be used as an example in the cathode of FIG. 1.

The present invention relates to a negative electrode in which a conductive polymer is coated in a uniform pattern, and more particularly, to a negative electrode in which a negative electrode mixture composed of a negative electrode active material, a binder, and a conductive material is adhered to a current collector and adhered thereto. To improve the bonding strength and electrical conductivity of the negative electrode mixture to the current collector, the secondary polymer, characterized in that the thin coating of a conductive polymer in a uniform pattern on the current collector, and the negative electrode mixture on the coating layer A negative electrode for a battery, and a secondary battery comprising such a negative electrode are provided.

As technology development and demand for mobile devices have increased, the demand for secondary batteries as energy sources has been rapidly increasing. Many researches have been conducted on lithium secondary batteries with high energy density and discharge voltage among such secondary batteries. .

In general, a lithium secondary battery uses a negative electrode produced by applying an electrode mixture obtained by mixing a conductive material and a binder with graphite carbon as a negative electrode active material to a current collector such as copper, and then pressing the electrode mixture.

However, in the negative electrode having the above structure, the electrode mixture adhering to the surface of the current collector is peeled off due to the volume change during repeated charging and discharging of the battery. This peeling phenomenon is one of the main causes of deterioration of battery performance and safety. In particular, the adhesion between the current collector and the electrode mixture mainly depends on the binder contained in the mixture, and PVdF, which is generally used as the binder, exhibits adhesive strength by physical bonding, and thus has a problem due to the weak bonding strength of the binder. There is a need for a solution.

On the other hand, due to the continuous development of secondary batteries, the natural graphite-based material as a negative electrode active material reaches its theoretical maximum capacity of 372 mAh / g (844 mAh / cc) almost to increase the capacity, there is a limit, so the next generation that changes rapidly It is difficult to play a sufficient role as an energy source of mobile devices.

Therefore, it is known that silicon, tin, or alloys thereof can reversibly occlude and release a large amount of lithium through a compound formation reaction with lithium, and much research has recently been conducted. have. For example, silicon is promising as a high capacity cathode material because the theoretical maximum capacity is about 4020 mAh / g (9800 mAh / cc, specific gravity 2.23), which is much larger than graphite-based materials.

However, since silicon, tin, and alloys thereof have a large volume change of 200 to 300% due to reaction with lithium during charging and discharging, the negative electrode active material detaches from the current collector or contacts the negative electrode active materials during continuous charge and discharge. Due to the increase in resistance due to a large change in the interface, as the charge and discharge cycle proceeds, there is a problem that the capacity is drastically lowered and the cycle life is shortened. Due to these problems, conventional binders for graphite-based negative electrode active materials, that is, polyvinylidene fluoride, styrene-butadiene rubber, etc. are used as they are for silicon-based or tin-based negative electrode active materials. In case you do not get the desired effect. In addition, when an excessive polymer is used as a binder to reduce volume change during charging and discharging, the detachment of the active material from the current collector may be slightly reduced, but the electrical resistance of the negative electrode is increased by the electrically insulating polymer as a binder, and the active material is relatively high. As the amount of is reduced, problems such as a decrease in capacity arise.

Therefore, in the conventional carbon-based lithium secondary battery, it is possible to improve the capacity of the battery by securing the adhesion between the active material and the current collector and the active materials, and when charging and discharging in a lithium secondary battery using a silicon or tin-based negative electrode active material There is an urgent need for development of a binder or electrode composition having excellent adhesion and mechanical properties capable of withstanding large volume changes of the negative electrode active material.

As a method for solving this problem, for example, there is a method of increasing the bonding strength with the electrode mixture by etching the surface of the copper current collector to form fine unevenness. This method has the advantage that a high specific surface area copper current collector can be obtained by a simple process, but has a problem in that the life of the copper current collector decreases due to the etching process.

As another method, Korean Patent No. 0362281 and Korean Patent No. 0573098 disclose a method of improving a bonding force with an electrode mixture by coating a conductive polymer on the surface of a current collector. However, the conductive polymer has an advantage of improving the bonding strength between the current collector and the electrode mixture, but has a disadvantage of lowering the electrical conductivity between the current collector and the electrode mixture. That is, when the conductive polymer is coated between the current collector and the electrode mixture, the electrical conductivity between the current collector and the electrode mixture is reduced than when the current collector and the electrode mixture are in direct contact. In particular, when the conductive polymer is applied to the entire surface of the current collector as in the above technique, the degree of decrease in electrical conductivity becomes more serious.

Therefore, there is a high demand for a technology capable of improving the bonding strength without compromising the electrical conductivity between the current collector and the mixture.

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

After extensive research and various experiments, the inventors of the present application have applied a conductive polymer on a current collector in a negative electrode on which a negative electrode mixture composed of a negative electrode active material, a binder, and a conductive material is applied onto a current collector. When a thin coating in a uniform pattern and the application of the negative electrode mixture on the coating layer, it was found that it is possible to improve the bonding strength of the negative electrode mixture to the current collector, while maintaining a significant electrical conductivity between the current collector and the mixture, The invention has been completed.

Accordingly, the negative electrode according to the present invention is a negative electrode in which a negative electrode mixture composed of a negative electrode active material, a binder, and a conductive material is adhered to a current collector and is in close contact with each other. In order to improve, the conductive polymer is thinly coated in a uniform pattern on the current collector, and the negative electrode mixture is coated on the pattern coating layer.

That is, the negative electrode according to the present invention can increase the bonding strength of the negative electrode mixture to the current collector at the portion where the conductive polymer is coated, and the electrode mixture directly contacts the current collector at the portion where the conductive polymer is not coated, The fall of conductivity can be minimized.

The conductive polymer is not particularly limited so long as it is a polymer having electrical conductivity, and preferably, may be one or two or more selected from the group consisting of polyacetylene, polypyrrole, polyaniline, and polythiophene.

The pattern coating layer of the conductive polymer is a range that does not adversely affect the overall volume of the finished battery without deteriorating the electrical conductivity while maintaining a stable bond between the current collector and the negative electrode mixture, preferably, 1 to 100 ㎛ thickness And an area of 20 to 80% of the current collector area. That is, if the thickness of the pattern coating layer is too thin or the coating area is too small, it is difficult to expect the improvement of the bonding strength due to the formation of the conductive polymer layer. On the contrary, if the pattern coating layer is too thick or the coating area is large, the internal resistance increase becomes large. May degrade performance.

In one preferred example, the pattern coating layer may be formed by applying a mixture containing a conductive polymer on the current collector and then drying. At this time, the coating method of the coating layer is not particularly limited and may be various, a representative example may be a spray coating method. In addition to the conductive polymer, the mixture may include a surfactant or the like such that the conductive polymer can be easily adhered to the surface of the current collector, and the conductive polymer and the surfactant may be, for example, in a solution such as NMP. It can be prepared by melting.

In another preferred example, the coating layer may be formed by putting a current collector in a mixture containing a conductive polymer forming monomer and an initiator and the conductive polymer is synthesized by the polymerization of the monomer on the current collector. In this case, in order to speed up the synthesis rate of the conductive polymer, a current may be applied to the current collector. More specifically, a mixture containing the monomer for forming the conductive polymer and the initiator is used as an electrolyte, and an electrochemical cell for synthesizing the conductive polymer is prepared by using, for example, a copper current collector and platinum as the counter electrode. By applying a current to the copper current collector and the platinum electrode, the conductive polymer can be electrochemically synthesized. That is, the monomer of the conductive polymer may be anodized polarization by an applied current to be coated with the conductive polymer on the surface of the current collector. As in the above-described example, the mixture may include a surfactant and the like so that the conductive polymer can be easily adhered to the surface of the current collector, and the monomer and initiator for forming the conductive polymer, and the surfactant, for example For example, it may be prepared by dissolving in a solution such as NMP.

In the above example, the monomer is not particularly limited as long as it can synthesize the conductive polymer by a polymerization reaction, and may vary. Preferably, in the group consisting of acetylene monomer, pyrrole monomer, aniline monomer, and thiophene monomer It may be one or more than one selected.

In the present invention, release paper may be used to thinly coat the conductive polymer in a uniform pattern, and the type of such release paper may be varied, for example, stripes (FIG. 2A), islands (FIG. 2B), Or honeycomb patterns (FIG. 2C). An exemplary method of patterning a conductive polymer using the release paper may be more easily confirmed in FIG. 1, in which a manufacturing process of a negative electrode is schematically illustrated.

Referring to FIG. 1, in the state in which the release paper 120 is attached on the copper current collector 110 a, the cathode 100 is coated and dried with a mixture 130 containing a conductive polymer (c). ), The release paper 120 may be removed (c), and then the negative electrode mixture 140 including the negative electrode active material, the binder, and the conductive material may be coated.

Although the above example is described as applying the conductive polymer to the copper current collector with release paper, it is possible to form a pattern coating layer by using the copper current collector with release paper in the polymerization reaction system of the conductive polymer as in the above example. Of course.

Examples of the negative electrode active material include carbon such as hardly graphitized carbon and graphite carbon; Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), Sn _x Me _{1 - x} Me ' _y O _z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, 2, 3 of the periodic table) Metal composite oxides such as a group element, halogen, 0 <x ≦ 1, 1 ≦ y ≦ 3, 1 ≦ z ≦ 8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , and metal oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like, but are not limited to these.

According to the present invention, a silicon-based compound, a tin-based compound, a tin-silicon-based compound, a silicon-carbon-based compound, etc., which have a high capacity but have a large volume change during charging and discharging, are more preferable. .

The binder is a component that assists in bonding the active material and the conductive agent to the current collector, and is generally added in an amount of 5 to 30 wt% based on the total weight of the mixture including the negative electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery. Examples of the conductive material include graphite such as natural graphite and artificial graphite; Carbon blacks 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 powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used. Specific examples of commercially available conducting agents include acetylene black Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company, Ketjenblack, EC series (Armak Company), Vulcan XC-72 (Cabot Company), and Super P (Timcal).

In the present invention, a filler may be further added to the negative electrode mixture as necessary. Such a filler is optionally used as a component that suppresses the expansion of the negative electrode, and is not particularly limited as long as it is a fibrous material without causing chemical change in the battery. Examples thereof include olefinic polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The negative electrode mixture may be added to a solvent such as NMP, prepared as a slurry, and then coated on a current collector having a conductive polymer coated thereon, followed by drying and compression to prepare a negative electrode.

The current collector for the cathode is generally made of a thickness of 3 to 500 ㎛. Such an anode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, and may be formed of a material such as copper, stainless steel, aluminum, nickel, titanium, fired carbon, 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 current collector, fine concavities and convexities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The present invention also provides a lithium secondary battery comprising such a negative electrode.

The lithium secondary battery according to the present invention is composed of a negative electrode, a positive electrode, a separator, and a lithium salt-containing nonaqueous electrolyte prepared by the above method.

The positive electrode is manufactured by applying, drying, and compressing a positive electrode material on a current collector, and, as necessary, may further include components as described above.

The current collector for the positive electrode is generally made to a thickness of 3 to 500 ㎛. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like on the surface may be used. The current collector may form fine irregularities on its surface to increase the adhesion of the positive electrode active material, and may be in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The positive electrode material may be, for example, a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO _2, and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , Cu ₂ V ₂ O ₇ and the like; Ni-site type lithium nickel oxide represented by the formula LiNi _1-x M _x O ₂ , wherein M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3; Formula LiMn _2-x M _x O ₂ (wherein M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (wherein M = Fe, Co, Lithium manganese composite oxide represented by Ni, Cu or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with alkaline earth metal ions; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The separator is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally from 0.01 to 10 ㎛ ㎛, thickness is generally 5 ~ 300 ㎛. As such a separator, for example, olefin polymers such as chemical resistance and hydrophobic polypropylene; Sheets or non-woven fabrics made of glass fibers or polyethylene are used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

The lithium salt-containing non-aqueous electrolyte consists of a nonaqueous electrolyte and a lithium salt. As the non-aqueous electrolyte, a non-aqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte and the like are used.

Examples of the nonaqueous electrolytic solution include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, But are not limited to, lactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, Nitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives , Tetrahydrofuran derivatives, ether, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, Polymers containing ionic dissociation groups, and the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides, sulfates and the like of Li, such as Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ , and the like, may be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4, LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide have.

In addition, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, etc. Nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxy ethanol, aluminum trichloride, etc. It may be. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or a carbon dioxide gas may be further added to improve high-temperature storage characteristics.

In one preferred embodiment, lithium salts such as LiPF ₆ , LiClO ₄ , LiBF ₄ , LiN (SO ₂ CF ₃ ) _2, and the like, may be prepared by cyclic carbonate of EC or PC as a highly dielectric solvent and DEC, DMC or EMC as a low viscosity solvent. The lithium salt-containing non-aqueous electrolyte can be prepared by adding to a mixed solvent of linear carbonate.

Hereinafter, the present invention will be described in more detail based on the following examples, but the scope of the present invention is not limited thereto.

Example 1

1-1. Manufacture of anode

94.5% by weight of LiCoO ₂ , 2.5% by weight of Super-P (conductor), and 2.5% by weight of PVDF (binder) were added to NMP (N-methyl-2-pyrrolidone) as a positive electrode active material to prepare a slurry for positive electrode mixture. After that, an anode was prepared by applying, drying and pressing on aluminum foil.

1-2. Preparation of Cathode

20% by weight polypyrrole and 0.5% by weight Pluronic ^™ F127 (BASF) as a surfactant were added to the NMP solution to prepare a mixture comprising the conductive polymer. Striped release paper with a size of 40% of the current collector area was coated and dried on a copper foil to which the stripe release paper was regularly attached as shown in FIG. 2A, and then the release paper was removed, and a conductive polymer was coated on the copper foil. Then, 95% by weight of artificial graphite, 2.5% by weight of Super-P (conductive material), and 2% by weight of PVDF (binder) were added to NMP as a solvent to prepare a negative electrode mixture, and then the conductive polymer was coated. The negative electrode was prepared by coating, drying and pressing on copper foil.

1-3. Preparation of Electrolyte

As the electrolyte solution, an EC / EMC solution containing a lithium salt of 1M LiPF ₆ was used.

1-4. Manufacture of batteries

A porous separator (Celgard ^TM ) was placed between the positive electrode and the negative electrode prepared in 1-1 and 1-2, respectively, and a non-aqueous electrolyte prepared in 1-3 was prepared to manufacture a lithium secondary battery.

[Example 2]

25% by weight of pyrrole monomer, 2% by weight of initiator and 0.5% by weight of Pluronic ^™ F127 (from BASF) as a surfactant were added to the NMP solution to prepare a mixture comprising a monomer for forming a conductive polymer, and the release paper contained Applying a current of 0.5 Ma / cm ² in a state of immersing the copper foil and platinum attached, remove the release paper by removing the copper current collector, except that the conductive polymer was coated on the copper current collector Was prepared in the same manner as in Example 1, the negative electrode and the battery.

Example 3

88% by weight of a silicon-carbon composite (Si-C) as a negative electrode active material, 10% by weight of PVA-26 (average degree of polymerization of 2600, saponification degree of 99% or more) as a binder, and 2% by weight of carbon black powder as a conductive material to DMSO. A negative electrode and a battery were prepared in the same manner as in Example 1 except for mixing and stirring for about 15 minutes to prepare a slurry for negative electrode mixture, and using the same to prepare a negative electrode.

Comparative Example 1

A negative electrode and a battery were manufactured in the same manner as in Example 1, except that the slurry for negative electrode mixture was applied, dried, and pressed without coating the conductive polymer on the copper foil.

Comparative Example 2

After the conductive polymer was coated on the entire surface of the copper foil, a negative electrode and a battery were manufactured in the same manner as in Example 1, except that the slurry for negative electrode mixture was applied, dried, and pressed.

Comparative Example 3

A negative electrode and a battery were manufactured in the same manner as in Example 3, except that the slurry for negative electrode mixture was applied, dried, and compressed without directly forming a pattern coating layer on the copper foil.

Experimental Example 1

In the negative electrode according to Examples 1 to 3 and Comparative Examples 1 to 3, in order to compare the bonding strength of the negative electrode mixture to the current collector, each of the prepared negative electrode surface was cut to a fixed size and fixed to the slide glass, copper foil Stripping strength was measured by peeling off 180, and the results are shown in Table 1 below. The peeling strength is a value measured at a negative electrode separated from the battery by discharging and discharging the battery 50 times continuously according to Examples and Comparative Examples. In this case, the cathode is in a state where the electrolyte is completely removed.

TABLE 1

As shown in Table 1, the negative electrodes of Examples 1 and 2 and Comparative Example 2 according to the present invention showed a higher electrode adhesion than the negative electrode of Comparative Example 1 is not coated with a conductive polymer. That is, it can be seen that the bonding strength of the negative electrode mixture to the current collector is improved by the conductive polymer. In the negative electrode of Comparative Example 3, the use of a large number of binders showed a high electrode adhesive force compared to Comparative Example 1, it can be seen that greatly falls compared to Example 3.

Experimental Example 2

In order to compare the electrical conductivity between the current collector and the negative electrode mixture in the negative electrode according to Examples 1 to 3 and Comparative Example 2, the resistance of the prepared negative electrode was measured, and the results are shown in Table 2 below.

TABLE 2

As shown in Table 2, in the cathodes of Examples 1 to 3 according to the present invention, since the conductive polymer is coated in a pattern shape, compared with the case where the conductive polymer is coated on the entire surface, the internal resistance is much smaller. Able to know.

As described above, the negative electrode according to the present invention has the effect of improving the bonding strength of the negative electrode mixture to the current collector, while maintaining a significant electrical conductivity between the current collector and the mixture.

Those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (11)

A negative electrode in which the negative electrode mixture composed of a negative electrode active material, a binder, and a conductive material is adhered to the current collector in close contact with the current collector, so that the binding strength and electrical conductivity of the negative electrode mixture to the current collector can be improved. Coating a conductive polymer in a uniform pattern, is prepared by applying a negative electrode mixture on the pattern coating layer and the pattern coating layer is a negative electrode for a secondary battery, characterized in that the thickness of 1 to 100 ㎛. The negative electrode of claim 1, wherein the conductive polymer is one or two or more selected from the group consisting of polyacetylene, polypyrrole, polyaniline, and polythiophene. delete The negative electrode of claim 1, wherein the pattern coating layer is coated with a coating area of 20 to 80% based on the area of the current collector. The negative electrode for a secondary battery of claim 1, wherein the pattern coating layer is formed by applying a mixture containing a conductive polymer onto a current collector having a release paper attached thereto in a pattern shape and drying the sheet, and then removing the release paper. The method of claim 1, wherein the pattern coating layer is a mixture containing a monomer for forming a conductive polymer and an initiator, the current collector is attached to the release paper in a pattern shape, and the conductive polymer is synthesized by the polymerization reaction of the monomer on the current collector After that, the secondary battery negative electrode, characterized in that formed by removing the release paper. The negative electrode of claim 6, wherein the monomer is one or two or more selected from the group consisting of an acetylene monomer, a pyrrole monomer, an aniline monomer, and a thiophene monomer. The negative electrode of claim 1, wherein the negative electrode active material is selected from the group consisting of crystalline carbon, amorphous carbon, silicon compound, tin compound, tin-silicon compound, and silicon-carbon compound. The negative electrode of claim 8, wherein the negative electrode active material is selected from the group consisting of a silicon compound, a tin compound, a tin-silicon compound, and a silicon-carbon compound. A secondary battery comprising the negative electrode according to any one of claims 1, 2 and 4 to 9. The secondary battery of claim 10, wherein the battery is a lithium secondary battery.

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