KR100490543B1 - Methods for producing negative electrode and lithium battery - Google Patents

Abstract

90 to 98 mass% of negative electrode active material, 0.8 to 5 mass% of SBR binder, 0.8 to 5 mass% of thickener, 0.01 to 1 mass% of silane coupling agent for improving the bonding strength of the negative electrode active material and the binder to the negative electrode plate Forming a negative electrode active material composition containing an amount of water; And laminating and drying the negative electrode active material on the negative electrode plate to form a negative electrode active material layer. Employing the method for producing a negative electrode according to the present invention can reduce the content of the binder and maintain sufficient adhesion between the negative electrode active material layer and the negative electrode plate, so that the amount of the negative electrode active material can be increased by that amount can increase the capacity of the lithium battery.

Description

Method for producing negative electrode and lithium battery

The present invention relates to a negative electrode plate and a method for manufacturing a lithium battery including the same, and more particularly to a negative electrode plate having excellent adhesion between the current collector and the negative electrode active material and a method for manufacturing a lithium battery comprising the same.

Recently, as the electronic equipment becomes smaller and lighter due to the development of advanced electronic devices, the use of portable electronic devices is gradually increasing. Accordingly, the necessity of a battery having a high energy density characteristic used as a power source of such an electronic device is increasing, and researches on lithium batteries, particularly lithium secondary batteries capable of charging and discharging are being actively conducted.

A lithium secondary battery is a battery manufactured by combining a separator and an organic electrolyte which provides a movement path of lithium ions between a cathode, an anode, and lithium ions, and intercalation / deintercalation of lithium ions at the anode and the cathode. The electrical energy is generated by the oxidation and reduction reactions at the same time. Such lithium secondary batteries can be classified into lithium ion batteries using liquid electrolytes and lithium polymer batteries using solid electrolytes, depending on the type of separator.

In the lithium secondary battery, the positive electrode and the negative electrode are made of a material capable of inserting and deinserting lithium ions. Looking at the forming material of the electrode, a lithium-containing metal oxide such as LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiMnO _2, and the like are used as a cathode active material.

As an anode active material of a lithium battery, the chemical potential at the time of insertion / deintercalation of lithium metal, a lithium-containing alloy, or lithium ion capable of reversibly accepting or supplying lithium ions while maintaining structural and electrical properties is substantially different from that of metallic lithium. Similar carbonaceous materials are mainly used.

The use of lithium metal or an alloy thereof as a negative electrode active material is called a lithium metal battery, and the use of a carbon material is called a lithium ion battery.

Lithium metal batteries using lithium metal or lithium alloys as negative electrodes are explosive due to battery short circuits due to the formation of dendrite, and are therefore being replaced by lithium ion batteries using carbon materials having no such risk as negative electrode active materials. . Lithium ion batteries have only a movement of lithium ions during charge and discharge, and thus the electrode active material remains intact, thereby improving battery life and stability compared to lithium metal batteries.

However, in accordance with the trend toward higher capacities of batteries, safety requirements are further increased, and thus, in the case of lithium ion batteries, a functional material should be selected to ensure safety even at a high capacity. In particular, as the capacity of the battery increases, battery safety must also be accompanied by an increase, and battery manufacturers continue to make efforts to secure safety with increasing battery capacity.

In the case of a lithium ion battery, a non-aqueous system in which polyvinylidene fluoride (PVDF) is dissolved in N-methyl-2-pyrrolidone (hereinafter referred to as NMP) or an acetone organic solvent is known as a binder of a negative electrode plate. I use it. However, in the case of using such a PVDF / NMP non-aqueous system as a binder, there are the following problems.

First, an organic solvent such as NMP or acetone has a health problem that seriously harms the health of workers who have been exposed to vapor evaporated therefrom for a long time.

Second, the organic solvent may pollute the environment, and the price is relatively high, thereby increasing the manufacturing cost of the lithium battery.

Third, since most of the organic solvents are highly volatile, when used in an enclosed space, there is a problem that explosion-proof equipment is required in order to prevent the explosion.

Fourth, PVDF has to use at least 6 ~ 8% by mass or more based on the total weight of the negative electrode active material layer in order to give sufficient binding force between the electrode plate and the active material due to poor adhesion. As such, when the amount of the binder is increased, the amount of the negative electrode active material decreases, so that a large capacity of the battery cannot be obtained.

Fifth, fluorine and lithium ions in PVDF react to form LiF, which is one of the causes of thermal runaway, which reduces the safety of lithium ion batteries. In particular, as the lithium ion battery becomes higher in capacity, such a phenomenon is increased, so it is difficult to secure battery safety.

Therefore, recently, in order to overcome this problem, in the production of a negative electrode plate, styrene-butadiene rubber (hereinafter referred to as "SBR") is dispersed in water together with a thickening agent carboxymethylcellulose (hereinafter referred to as "CMC"). Attempts have been made to use aqueous binder systems. This is because SBR can be dispersed in water in the form of an emulsion, which does not require the use of an organic solvent, and because the adhesion is strong, it is advantageous for high capacity of a lithium battery by reducing the binder content and increasing the content of the negative electrode active material. However, even in this case, if the content of SBR is reduced too much, the following new problem occurs.

First, since the adhesive force between the negative electrode active material and the negative electrode plate is insufficient, the negative electrode active material and the negative electrode plate are detached by the tension in the winding process during battery manufacturing.

Second, since the negative electrode active material layer and the negative electrode plate are partially detached due to shrinkage and relaxation due to repeated charging and discharging during use, abnormal resistance may occur due to an increase in resistance, thereby reducing the capacity of the battery.

Therefore, the technical problem to be achieved by the present invention is to solve the above problems, even when using a low-content SBR aqueous binder system for the negative electrode active material layer can obtain a negative electrode (negative electrode) is enhanced the binding strength of the negative electrode plate and the negative electrode active material layer It is to provide a method for producing a negative electrode.

Another technical problem to be achieved by the present invention is to provide a method of manufacturing a lithium battery which can increase the battery capacity by using the negative electrode.

In order to achieve the above technical problem, the present invention, the negative electrode active material 90 ~ 98% by mass, SBR binder 0.8 ~ 5% by mass, thickener 0.8 ~ 5% by mass, to improve the binding force of the negative electrode active material and the binder to the negative electrode plate Forming a negative electrode active material composition containing 0.01 to 1% by mass of the silane coupling agent and the remaining amount of water for; And

It provides a method for producing a negative electrode comprising the step of laminating the negative electrode active material on the negative electrode plate and dried to form a negative electrode active material layer.

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In order to achieve the above another technical problem, the present invention also provides a negative electrode active material 90 to 98 mass%, SBR binder 0.8 to 5 mass%, thickener 0.8 to 5 mass%, the bonding strength of the negative electrode active material and the binder to the negative electrode plate Preparing a negative electrode by laminating a negative electrode active material composition containing 0.01 to 1% by mass of a silane coupling agent and a residual amount of water on the negative electrode plate and drying to form a negative electrode active material layer; Inserting a separator between the positive electrode made of a compound capable of occluding and releasing, and winding or stacking the separator to form an electrode structure, and then placing the separator in a battery case; And

It provides a method of manufacturing a lithium battery comprising the step of injecting a non-aqueous electrolyte in which the lithium salt electrolyte solute is dissolved in the battery case.

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In the method of manufacturing a negative electrode and a lithium battery according to the present invention, the silane coupling agent is a vinyl silane coupling agent, an amino silane coupling agent, a (meth) acrylic silane coupling agent, an epoxy silane coupling agent, a mercapto silane coupling agent. , An alkoxy silane coupling agent or a combination thereof.

In the method for producing a negative electrode and a lithium battery according to the present invention, the vinyl silane coupling agent is vinyl trimethoxy silane, vinyl triethoxy silane, vinyl trichlorosilane, vinyl tris (2-methoxy ethoxy) silane, or It is preferable that it is a combination of these.

In the method of manufacturing a negative electrode and a lithium battery according to the present invention, the thickener is preferably selected from the group consisting of carboxy methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

In the method of manufacturing a negative electrode and a lithium battery according to the present invention, the negative electrode plate is preferably copper or a copper-based alloy.

In the method of manufacturing a negative electrode and a lithium battery according to the present invention, the negative electrode active material is preferably made of a carbon material composed of natural graphite, artificial graphite, graphitizable carbon, non-graphitizable carbon, or a combination thereof as a main material.

In the method of manufacturing a lithium battery according to the present invention, the compound that can occlude and release lithium is preferably at least one selected from the group consisting of LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiCrO ₂ , and LiMn ₂ O ₄ . .

In the method of manufacturing a lithium battery according to the present invention, the electrolyte solute consists of LiPF ₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ and LiAsF ₆ It is preferably selected from the group.

In the negative electrode according to the present invention, even when only a small amount of SBR binder is used by the adhesion enhancing action of the silane coupling agent, the negative electrode active material due to the tension in the winding process during battery manufacturing is sufficient because the adhesive force between the negative electrode active material and the negative electrode plate is sufficient for practical purposes. It is advantageous to reduce the detachment phenomenon of the layer and the negative electrode plate, the abnormal exothermic phenomenon caused by shrinkage and relaxation caused by repeated charge and discharge during use, and the subsequent decrease in battery capacity.

Hereinafter, a negative electrode according to the present invention and a method of manufacturing a lithium battery employing the same will be described.

According to an embodiment of the present invention, a method of manufacturing a negative electrode includes: 90 to 98 mass% of a negative electrode active material, 0.8 to 5 mass% of a SBR binder, 0.8 to 5 mass% of a thickener, and a bonding force between the negative electrode active material and the binder to the negative electrode plate. Forming a negative electrode active material composition containing 0.01 to 1 mass% of silane coupling agent and a residual amount of water to enhance the amount of water; And

It provides a method for producing a negative electrode comprising the step of laminating the negative electrode active material on the negative electrode plate and dried to form a negative electrode active material layer.

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The SBR binder can eliminate the problems that can occur when using a fluorine-containing binder such as PVDF, a copolymer of vinylidene chloride and hexafluoropropylene, and also has an adhesive force with the electrode plate. Better than Therefore, the use of the SBR binder may not experience the above-mentioned disadvantages of dry, environmental and equipment, and may also reduce the amount of use, and increase the proportion of the negative electrode active material in the negative electrode active material layer, thereby increasing the capacity of the battery. It is advantageous to It is preferable that it is 0.8-5 mass% with respect to the mass of the whole negative electrode active material layer, and, as for content of an SBR binder, it is more preferable that it is 1-5 mass%. If the content of SBR binder is less than 0.8% by mass, the content of the binder is too small, resulting in insufficient adhesion between the negative electrode active material layer and the negative electrode plate. This is disadvantageous since the advantage of using an SBR binder instead of a fluorine-based polymer such as PVDF is eliminated.

In the negative electrode active material of the present invention, a thickener is used for the purpose of viscosity control, and the content of the thickener is preferably 0.8 to 5% by mass, more preferably 1 to 5% by mass. If the content of the thickener is less than 0.8% by mass, there is a problem flowing down when coating the active material, when the content exceeds 5% by mass, the viscosity is too high, there is a problem that the coating is difficult and serves as a resistance.

The thickener is not particularly limited as long as it can play a role of viscosity control of the active material slurry, but is specifically selected from the group consisting of carboxy methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. Can be used.

In the present invention, the total content of the SBR binder + thickener is preferably adjusted to 1.5 to 5% by mass based on the mass of the negative electrode active material layer in order to maximize the capacity of the battery. The total content of the SBR binder + thickener is significantly higher than that of 6 to 8 mass% based on the total mass of the negative electrode active material layer, which is a conventional content when adopting a fluorine-based polymer binder such as PVDF. It is degraded. Accordingly, the negative electrode of the present invention uses a silane coupling agent to compensate for the decrease in adhesion force due to the decrease in the binder component.

Silane coupling agents have two or more different reactors in their molecular structure. One is a methoxy group, an ethoxy group, etc., capable of chemically bonding inorganic materials such as glass, metal, sand, etc. The other is a vinyl group, an epoxy group, an amino group, (m) acryl, which can be chemically bonded to an organic polymer binder. Groups, mercapto groups and the like. Thus, the silane coupling agent serves to increase the adhesion or bonding force between materials with significantly different material properties, such as organic and inorganic materials.

The silane coupling agent that can be used in the present invention is not particularly limited, but specific examples thereof include vinyltrichlorosilane, vinyltris (2-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, and the like. Vinylsilane-based coupling agents; (Meth) acrylic silane coupling agents such as 3-methacryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; Epoxy silane coupling agents such as 2- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, and 3-glycidyloxypropylmethyldiethoxysilane; N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3 Amino silane coupling agents such as -aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; Alkoxy silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane; 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, etc. are mentioned.

Among the above silane coupling agents, vinyltrichlorosilane, vinyltris (2-methoxyethoxy) silane, vinyltriethoxysilane, vinyl in terms of increasing the adhesion between the negative electrode plate made of copper and a copper-based alloy and the SBR binder. Vinyl silane coupling agents, such as trimethoxysilane, are preferable.

In the present invention, as the negative electrode plate, a copper plate or a copper-based alloy plate (hereinafter simply referred to as "copper plate") is preferably used. When the copper plate is exposed to air, the first copper oxide (Cu ₂ O), the second copper oxide (CuO), copper hydroxide (Cu (OH) ₂ ), chemisorbed water, and carboxylate species ( The film layer is mixed with carboxylate species. In addition, oxygen-dissolved water generates hydroxyl groups on the copper surface and activates the surface of the copper plate by the following chemical reaction.

Cu + H ₂ O → CuO + H ₂

2Cu + H ₂ O → Cu ₂ O + H ₂

Cu + 2H ₂ O → Cu (OH) ₂ + H ₂

Taking the vinyltriethoxysilane coupling agent as an example, the silane coupling agent used in the present invention will be described as follows to improve the adhesion between the negative electrode active material and the negative electrode plate.

When ethoxy of vinyltriethoxysilane is hydrolyzed, silanol groups are formed. This silanol group causes a dehydration condensation reaction with hydroxyl groups formed on the copper plate and / or the negative electrode active material by a mechanism as described above, and consequently, a silane organic layer having vinyl groups on the surface of the copper plate and / or the negative electrode active material through covalent bonds. Will form. Thus, by forming such a layer, the copper plate and / or the negative electrode active material can be combined with the SBR resin. Silane coupling agents other than the vinyl silane coupling agent firmly bond the SBR resin with the copper plate and / or the negative electrode active material by a similar mechanism.

In addition to the above covalent bonds, it is speculated that secondary chemical bonds such as hydrogen bonds or van der Waals bonds, which may be formed between the copper plate and / or the negative electrode active material and the silane coupling agent, may increase adhesion. As a result, the silane coupling agent serves to enhance the adhesion between the negative electrode active material and the negative electrode plate.

The content of the silane coupling agent is preferably 0.01 to 1% by mass, more preferably 0.01 to 0.5% by mass, and most preferably 0.01 to 0.1% by mass based on the total mass of the negative electrode active material layer. When the content of the silane coupling agent is less than 0.01% by mass, the effect of strengthening the adhesion is insufficient, and even more than 1% by mass, it is difficult to expect more adhesion strengthening effect.

As the negative electrode active material used for the negative electrode active material layer, a carbon material composed of natural graphite, artificial graphite, graphitizable carbon, non-graphitizable carbon, or a combination thereof is used as the main material.

Hereinafter, the manufacturing method of the lithium battery which employ | adopted the negative electrode of this invention is demonstrated.

Method for manufacturing a lithium battery according to an embodiment of the present invention, the negative electrode active material 90 ~ 98 mass%, SBR binder 0.8 ~ 5 mass%, thickener 0.8 ~ 5 mass%, the negative electrode active material and the binder to the negative electrode plate Preparing a negative electrode by laminating a negative electrode active material composition containing 0.01 to 1% by mass of a silane coupling agent and a residual amount of water to enhance bonding strength and drying the negative electrode active material to form a negative electrode active material layer; Inserting a separator between the positive electrode made of a compound capable of occluding and releasing lithium and winding or stacking the separator to form an electrode structure, and then placing the separator in a battery case; And injecting a non-aqueous electrolyte in which a lithium salt electrolyte solute is dissolved into the battery case.

In the method of manufacturing a lithium battery according to an embodiment of the present invention, the configuration of the negative electrode is as described above, and the positive electrode is LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiCrO ₂ , and LiMn on a positive electrode plate made of aluminum or an aluminum-based alloy. A structure in which a cathode active material layer including at least one conductive material selected from the group consisting of a compound capable of occluding and releasing any one or more lithium selected from the group consisting of ₂ O ₄ , a binder, carbon black, acetylene black, and ketene black is laminated It is. The binder used in the positive electrode active material layer may be a fluorine-containing binder such as PVDF, a copolymer of vinylidene chloride and hexafluoropropylene, as well as the SBR / thickener used in the negative electrode active material layer.

The separator is used to separate the cathode and the anode and to provide a migration path for lithium ions. The polyethylene separator, polypropylene separator, polyvinylidene fluoride separator, vinylidene fluoride and hexafluoropropylene copolymer separator, polyethylene / poly Polyolefin separators or fluorinated polyolefin separators such as a two-layer separator of propylene, a three-layer separator of polypropylene / polyethylene / polypropylene, or a three-layer separator of polyethylene / polypropylene / polyethylene can be used.

The electrode assembly consisting of the cathode / separator / anode is impregnated with an electrolyte. This electrolyte has a structure in which an electrolyte solute is dissolved in a non-aqueous solvent.

As the electrolyte solute, one selected from the group consisting of LiPF ₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) _2, and LiAsF ₆ can be preferably used. The concentration of the electrolyte solute can be used typically 0.8 ~ 3.0M.

The non-aqueous solvent is 20 to 80% by volume of ethylene carbonate based on the volume of the solvent; And ethylene thiocarbonate, γ-thiobutyrolactone, α-pyrrolidone, γ-butyrolactone, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, γ-valerolactone, γ -Ethyl-γ-butyrolactone, β-methyl-γ-butyrolactone, thiolane, pyrazolidine, pyrrolidine, tetrahydrofuran, 3-methyltetrahydrofuran, sulfolane, 3-methylsulfuran, A mixed solvent of 20 to 80% by volume of at least one cyclic compound selected from the group consisting of 2-methyl sulfolane, 3-ethyl sulfolane and 2-ethyl sulfolane can be preferably used.

The non-aqueous solvent is dimethyl carbonate, diethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane and 1,2-diethoxymethoxyethane, methylethyl carbonate, vinylene carbonate, triglyme, It may further comprise at least one low boiling point solvent selected from the group consisting of tetraglyme, fluorobenzene, difluorobenzene.

Next, a negative electrode according to an embodiment of the present invention and a method of manufacturing a lithium battery employing the same will be described in more detail.

First, the method of preparing the negative electrode active material composition is as follows. Thickener powders such as carboxy methyl cellulose (hereafter CMC) are added to pure water at pH about 7 with stirring. Stirring is continued until no precipitate is formed at room temperature, thereby preparing a thickener aqueous solution having a concentration of about 1 to 2% by mass. Subsequently, it is left at room temperature for 0.5 to 5 hours to stabilize the molecular chain of CMC. At this time, it is preferable that there is little change in viscosity of this CMC aqueous solution. Next, the CMC aqueous solution is mixed so as to be uniformly mixed with a homogenizer and added to the negative electrode active material several times. Once the mixing of both is made uniform, the SBR binder is added to the mixture and stirred to mix uniformly.

Finally, an appropriate amount of silane coupling agent is added to the mixture of the negative electrode active material / SBR binder / thickener thus prepared and uniformly mixed to complete the preparation of the negative electrode active material composition. The negative electrode can be obtained by applying this negative electrode active material composition onto a thin copper plate using a doctor blade and drying in an oven at 60 to 90 ° C.

In preparing the negative electrode active material composition, the content of the solid content including the negative electrode active material, the binder, and the thickener in pure water is preferably controlled to 35 to 60 mass% for easy process. The content of each component in the solid is as described above.

On the other hand, the negative electrode active material composition may be prepared by further including an additive commonly used in the field of the present invention in order to improve the conductivity or to facilitate the process, if necessary.

Next, the manufacturing method of the lithium battery which concerns on this invention is demonstrated. The lithium battery according to the present invention may be manufactured according to a conventional method for manufacturing a lithium battery.

That is, a positive electrode is manufactured by the conventional method used at the time of manufacturing a lithium battery. The negative electrode is prepared according to the method described above. In this case, in addition to the lithium metal oxide described above, a lithium metal composite oxide, a transition metal compound, a sulfur compound, and the like may be used as the positive electrode active material.

Thereafter, a separator is inserted between the positive electrode plate and the negative electrode plate, and the electrode structure is formed by winding or stacking the separator and then putting the separator into a battery case to assemble the battery.

Thereafter, the non-aqueous electrolyte solution in which the lithium salt is dissolved or dispersed is injected into the battery case in which the electrode structure is stored, and then thermally crimped to complete the lithium secondary battery.

Hereinafter, the present invention will be described in detail with reference to the following examples, but the present invention is not limited only to the following examples.

Example

After adding 150 g of CMC (manufacturer: Dicell, brand name: 1380) powder to a pure water of 1000 ml pH of about 7 with stirring, the mixture was stirred at room temperature until there was no precipitate. Prepared. The aqueous solution was left at room temperature for about 3 hours. Next, 100 g of crystalline graphite (manufactured by Nippon Carbon Co., Ltd., trade name: P15B-HG) was added three times and mixed uniformly while stirring this 1.5 mass% CMC aqueous solution in a homogenizer. Subsequently, 3.87 g of 40 mass% SBR binder aqueous emulsion was added to the mixture and stirring was continued to mix uniformly. Finally, to the mixture of graphite / SBR binder / CMC, 1 g of 0.1% by mass of the silane coupling agent diluted with 0.1 g of the silane coupling agent in 100 g of a mixture of methanol / pure = 5/95% by mass was added and mixed uniformly. A negative electrode active material slurry was prepared.

The negative electrode active material composition was coated on a copper foil having a thickness of 25 μm using a doctor blade, then dried and rolled in an oven at 80 ° C., and cut into predetermined dimensions to prepare a negative electrode.

Comparative example

A negative electrode was manufactured in the same manner as in the above example except that a silane coupling agent was not used in preparing the negative electrode active material slurry.

Anti-peeling test

The anti-pilling test was performed based on ASTM D903 for the negative electrode prepared according to the above Examples and Comparative Examples.

1 illustrates a negative electrode specimen shape used in the peeling resistance test of the present invention. Referring to FIG. 1, the negative electrode specimen was a 2.5cm × 7cm rectangular flake having an area of 2.5cm × 3cm to which the anode active material layer and the copper foil were bonded and the remaining area.

2 is a schematic view for explaining a method of performing a peeling resistance test using the negative electrode specimen. As shown in FIG. 2, the foil foil which is not covered with the negative electrode active material layer and the unbonded region are bent and held in a tensile tester, and then stretched at a tensile speed of 10 cm / min to provide a gap between the negative electrode active material layer and the copper foil. Adhesion was measured.

Peeling resistance was measured for each of the ten negative electrode specimens prepared according to Examples and Comparative Examples, and then evaluated as the lowest, highest and average values. The results are shown in Table 1 below.

division Adhesive force (gf / mm) Minimum value Value medium Example 8.51 10.78 9.85 Comparative example 5.13 5.37 5.26

Referring to Table 1, the negative electrode prepared according to the Example showed an increase in adhesion of about 90% compared to its average value of 5.26.gf/mm, which was prepared according to the comparative example, with an average value of adhesion of 9.85 gf / mm.

As described above, the negative electrode of the present invention can exhibit an effect of significantly increasing the adhesive force between the negative electrode plate and the negative electrode active material layer as compared with the case where no silane coupling agent is used. Therefore, employing the negative electrode according to the present invention in a lithium battery has the following advantages.

(1) The negative electrode active material and the negative electrode plate are detached by the tension during the winding step.

(2) Abnormal exothermic phenomena due to increased resistance caused by partial detachment of the negative electrode active material layer and the negative electrode plate due to shrinkage and relaxation due to repeated charging and discharging can be reduced.

(3) Compared with the case of using a conventional fluorine-based binder, the amount of binder used can be greatly reduced, and the lithium battery can be made high in capacity.

Although the present invention has been described with reference to the above embodiments, it is merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. . For example, while the present invention has been described for lithium ion batteries, those skilled in the art will recognize that the negative electrode of the present invention can also be applied to lithium polymer batteries. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 illustrates a negative electrode specimen shape used in the peeling resistance test of the present invention.

Figure 2 is a schematic diagram for explaining a method of performing a peeling resistance test using a negative electrode specimen.

Claims (16)

90 to 98 mass% of negative electrode active material, 0.8 to 5 mass% of SBR binder, 0.8 to 5 mass% of thickener, 0.01 to 1 mass% of silane coupling agent for improving the bonding strength of the negative electrode active material and the binder to the negative electrode plate Forming a negative electrode active material composition containing an amount of water; And Stacking and drying the negative electrode active material on the negative electrode plate to form a negative electrode active material layer. The silane coupling agent according to claim 1, wherein the silane coupling agent is a vinyl silane coupling agent, an amino silane coupling agent, a (meth) acrylic silane coupling agent, an epoxy silane coupling agent, a mercapto silane coupling agent, an alkoxy silane coupling agent or these Method for producing a negative electrode, characterized in that the combination. The vinyl silane coupling agent is vinyl trimethoxy silane, vinyl triethoxy silane, vinyl trichlorosilane, vinyl tris (2-methoxy ethoxy) silane, or a combination thereof. Method for producing a negative electrode. The method of claim 1, wherein the thickener is selected from the group consisting of carboxy methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. The method of claim 1, wherein the negative electrode plate is a copper or copper-based alloy manufacturing method of the negative electrode. The method of claim 1, wherein the negative electrode active material is made of a carbon material consisting of natural graphite, artificial graphite, graphitizable carbon, non-graphitizable carbon, or a combination thereof as a main material. The manufacturing method of the negative electrode made into. 90 to 98 mass% of negative electrode active material, 0.8 to 5 mass% of SBR binder, 0.8 to 5 mass% of thickener, 0.01 to 1 mass% of silane coupling agent for improving the bonding strength of the negative electrode active material and the binder to the negative electrode plate Preparing a negative electrode by laminating a negative electrode active material composition containing an amount of water on a negative electrode plate and drying the same to form a negative electrode active material layer; Inserting a separator between the negative electrode obtained above and a positive electrode made of a compound capable of occluding and releasing lithium, and winding or stacking the separator to form an electrode structure and then placing the separator in a battery case; And A method of manufacturing a lithium battery comprising the step of injecting a non-aqueous electrolyte in which a lithium salt electrolyte solute is dissolved in the battery case. 8. The silane coupling agent of claim 7, wherein the silane coupling agent is a vinyl silane coupling agent, an amino silane coupling agent, an acrylic silane coupling agent, an epoxy silane coupling agent, a halogenated alkyl silane coupling agent, a mercapto silane coupling agent, an alkoxy silane. It is a coupling agent or a combination thereof, The manufacturing method of the lithium battery characterized by the above-mentioned. The vinyl silane coupling agent is vinyl trimethoxy silane, vinyl triethoxy silane, vinyl trichlorosilane, vinyl tris (2-methoxy ethoxy) silane, or a combination thereof. Method for producing a lithium battery. The method of claim 7, wherein the thickener is selected from the group consisting of carboxy methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. The method of manufacturing a lithium battery according to claim 7, wherein the negative electrode plate is copper or a copper-based alloy. 8. The negative electrode active material of claim 7, wherein the anode active material is made of a carbon material composed of natural graphite, artificial graphite, graphitizable carbon, non-graphitizable carbon, or a combination thereof. The manufacturing method of the lithium battery. The method of manufacturing a lithium battery according to claim 7, wherein the compound capable of occluding and releasing lithium is at least one selected from the group consisting of LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiCrO ₂ , and LiMn ₂ O ₄ . . 8. The method of claim 7, wherein the electrolyte solute is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ and LiAsF ₆ Method for producing a lithium battery. The method of claim 7, wherein the solvent is based on the volume of the solvent, 20 to 80% by volume ethylene carbonate; And Ethylene thiocarbonate, γ-thiobutyrolactone, α-pyrrolidone, γ-butyrolactone, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, γ-valerolactone, γ- Ethyl-γ-butyrolactone, β-methyl-γ-butyrolactone, thiolane, pyrazolidine, pyrrolidine, tetrahydrofuran, 3-methyltetrahydrofuran, sulfolane, 3-methylsulfuran, 2 -20 to 80% by volume of at least one cyclic compound selected from the group consisting of methyl sulfolane, 3-ethyl sulfolane and 2-ethyl sulfolane. The method of claim 15, wherein the solvent is dimethyl carbonate, diethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-diethoxymethoxyethane, methylethyl carbonate, vinylene carbonate, A method for manufacturing a lithium battery, further comprising at least one low boiling point solvent selected from the group consisting of triglyme, tetraglyme, fluorobenzene, and difluorobenzene.