KR20040053492A - Negative electrode and lithium battery employing the same - Google Patents

Abstract

PURPOSE: A negative electrode and a lithium battery employing the negative electrode are provided, to improve the binding force between a negative electrode active material layer and an electrode plate even with reducing the content of a binder. CONSTITUTION: The negative electrode comprises a negative electrode plate; and a negative electrode active material layer placed on the plate which comprises 90-98 wt% of a negative electrode active material, 0.8-5 wt% of an SBR binder, 0.8-5 wt% of a thickener, and 0.01-1 wt% of a dicarboxylic acid for improving the binding force between the negative electrode active material and the binder and the electrode plate. Preferably the dicarboxylic acid is a C2-C20 alkane dicarboxylic acid or a C4-C20 alkene dicarboxylic acid; the electrode plate is made of copper or a copper-based alloy; and the active material comprises a natural carbon, an artificial carbon, a graphitizable carbon, a non-graphitizable carbon or their combinations.

Description

Negative electrode and lithium battery employing the same}

The present invention relates to a negative electrode plate and a lithium battery comprising 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 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 movement of lithium ions during charging and discharging, and thus the electrode active materials remain 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 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 the adhesion is strong, which is advantageous for high capacity of a lithium battery by decreasing the content of the binder 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 provide a negative electrode (negative electrode) is strengthened the binding between the negative electrode plate and the negative electrode active material layer even when using a low content SBR aqueous binder system for the negative electrode active material layer to solve the above problems. will be.

Another object of the present invention is to provide a lithium battery capable of increasing battery capacity by using the negative electrode.

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.

One embodiment of the present invention to achieve the above technical problem,

Negative electrode plate; And

90 to 98% by mass of the negative electrode active material, 0.8 to 5% by mass of the SBR binder, 0.8 to 5% by mass of a thickener, and 0.01 to 1% by mass of dicarboxylic acid for enhancing the binding force between the negative electrode active material and the binder to the negative electrode plate. It provides, the negative electrode comprising a negative electrode active material layer placed on the negative electrode plate.

One embodiment of the present invention to achieve the above other technical problem,

A negative electrode composed mainly of a carbon material;

A positive electrode composed of a compound capable of occluding and releasing lithium;

A separator interposed between the positive electrode and the negative electrode; And

An electrolyte solution in which an electrolyte solute is dissolved in a non-aqueous solvent,

The negative electrode is a negative electrode comprising a negative electrode active material layer including a negative electrode active material containing the carbon material as a main material laminated on the negative electrode plate, the negative electrode active material layer is 90 to 98 mass% of negative electrode active material, 0.8 to 5 mass% of SBR binder, Provided is a lithium battery comprising 0.8 to 5% by mass of a thickener, and 0.01 to 1% by mass of dicarboxylic acid for enhancing the bonding strength of the negative electrode active material and the binder to the negative electrode plate.

In the negative electrode and lithium battery according to an embodiment of the present invention, the dicarboxylic acid is preferably C2 to C20 alkane dicarboxylic acid, C4 to C20 alkene dicarboxylic acid or a combination thereof.

In the negative electrode and lithium battery according to an embodiment of the present invention, the C2 to C20 alkane dicarboxylic acid or C4 to C20 alkene dicarboxylic acid is preferably malonic acid, maleic acid, fumaric acid or a combination thereof. Do.

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

In the negative electrode and lithium battery according to an embodiment of the present invention, the negative electrode active material is made of natural graphite, artificial graphite, graphitizable carbon, non-graphitizable carbon, or a combination thereof It is preferable that a carbon material is used as the main material.

In the lithium battery according to an embodiment of the present invention, the compound capable of occluding and releasing 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 . Do.

In a lithium battery according to an embodiment of the present invention, the electrolyte solute is 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 consisting of.

Since the negative electrode according to the present invention has sufficient adhesive strength between the negative electrode active material and the negative electrode plate even when only a small amount of SBR binder is used by the adhesion promoting action of aliphatic alkane dicarboxylic acid or alkene dicarboxylic acid of C2 to C20. It is advantageous to reduce the detachment phenomenon of the negative electrode active material layer and the negative electrode plate due to the tension in the winding process during battery manufacturing, the abnormal exothermic phenomenon caused by the shrinkage / relaxation caused by the repeated charge / discharge during use, and the decrease of the battery capacity.

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

The negative electrode according to the embodiment of the present invention,

A negative electrode plate made of copper or a copper-based alloy; And

90 to 98% by mass of the negative electrode active material, 0.8 to 5% by mass of the SBR binder, 0.8 to 5% by mass of a thickener, and 0.01 to 1% by mass of dicarboxylic acid for enhancing the binding force between the negative electrode active material and the binder to the negative electrode plate. It provides, the negative electrode comprising a negative electrode active material layer placed on the negative electrode plate.

The SBR binder can eliminate the problems that may occur when using a fluorine-containing binder such as PVDF, copolymer of vinylidene chloride and hexafluoropropylene, and also has better adhesion to the electrode plate than the fluorine-containing binder. Do. Therefore, the use of the SBR binder may not experience the above-mentioned disadvantages of health, environment, and equipment, and may also reduce the amount of binder used, thereby increasing the proportion of the negative electrode active material in the negative electrode active material layer. It is advantageous for high capacity. The content of the SBR binder is preferably 0.8 to 5% by mass, more preferably 1 to 5% by mass, and most preferably 1 to 2.0% by mass based on the mass of the entire negative electrode active material layer. 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, most preferably 1 to 2.0% by mass. Do. 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 slurry viscosity control, and specific examples include those selected from the group consisting of carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. Can be.

In the present invention, the total content of the SBR binder + thickener is preferably adjusted to 1.5 to 4% 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 dicarboxylic acid to compensate for the decrease in adhesion force due to the reduction of the binder component.

Dicarboxylic acid has two carboxyl groups in molecular structure. This carboxyl group bonds between the copper or copper alloy used as the negative electrode plate and the SBR binder, and consequently serves to increase the adhesion or bonding force between the negative electrode active material layer and the negative electrode plate. Although the nature of the bond is not clear, the carboxyl group reacts with a reactive group present at the end group of the SBR binder to form a covalent bond or a hydrogen bond or van derergy between a double bond present in a phenyl group or butadiene residue in the SBR binder. It is assumed to form secondary bonds, such as Vals bonds.

It is believed that the dicarboxylic acid can also cause dehydration condensation reaction with hydroxyl groups formed on the copper plate and / or the negative electrode active material which is the negative electrode plate to form ester covalent bonds. Therefore, dicarboxylic acid can improve the adhesive force of a negative electrode plate and a negative electrode active material layer.

The dicarboxylic acid that can be used in the present invention is not particularly limited, but specific examples thereof include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suveric acid, azelaic acid, seba Aliphatic alkanes dicarboxylic acids of C2 to C20 such as sebacic acid; It is preferable that they are C4-C20 alkene dicarboxylic acid, such as maleic acid, a fumaric acid, itaconic acid, or a combination thereof. Especially, it is preferable that it is malonic acid, maleic acid, fumaric acid, or a combination thereof from the point of the outstanding adhesive strength effect, the odor free, the solubility with an aqueous negative electrode active material composition, etc.

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

If the dicarboxylic acid compound is estimated by explaining the mechanism that can improve the adhesion between the negative electrode active material and the negative electrode plate as follows.

The dicarboxylic acid may cause 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 may chemically bond to the surface of the copper plate and / or the surface of the negative electrode active material through covalent bonds. . In addition, the dicarboxylic acid may be chemically bonded to the SBR resin through a secondary bond such as covalent bonds or hydrogen bonds, van der Waals bonds as described above. Accordingly, the dicarboxylic acid can enhance the bonding force between the copper electrode plate and the negative electrode active material or between the copper electrode plate and the SBR resin by secondary bonding such as covalent bonds or hydrogen bonds. As a result, the adhesion between the negative electrode active material layer and the negative electrode plate may be improved.

It is preferable that dicarboxylic acid is 0.01-1 mass% with respect to the gross mass of a negative electrode active material layer, It is more preferable that it is 0.01-0.5 mass%, It is most preferable that it is 0.01-0.1 mass%. If the content of the dicarboxylic acid 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 lithium battery which employ | adopted the negative electrode of this invention is demonstrated.

A lithium battery according to an embodiment of the present invention has a structure in which a separator is interposed between a negative electrode made of a carbon material as a main material and a positive electrode made of a compound capable of occluding and releasing lithium. The negative electrode is a negative electrode formed by laminating a negative electrode active material layer containing a negative electrode active material containing the carbon material as a main material on a negative electrode plate, wherein the negative electrode active material layer is 90 to 98 mass% of the negative electrode active material, 0.8 to 5 mass% of SBR binder, thickener 0.8-5 mass%, 0.01-1 mass% of dicarboxylic acid for improving the binding force of the said negative electrode active material and the said binder to the said negative electrode plate.

In the lithium battery according to the exemplary embodiment of the present invention, the negative electrode is configured as described above, and the positive electrode is LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiCrO ₂ , and LiMn ₂ O ₄ on a positive electrode plate made of aluminum or an aluminum-based alloy. The positive electrode 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 a binder, carbon black, acetylene black, and ketene black is laminated. . The binder used for the positive electrode active material layer is preferably a fluorine-containing binder such as PVDF, a copolymer of vinylidene chloride and hexafluoropropylene.

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 electrolyte solute may typically be used in the range of 0.8 to 3.0 M concentration.

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.

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 dicarboxylic acid 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. At this time, some of the dicarboxylic acid may be removed by evaporation.

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, a method of manufacturing a lithium battery according to an embodiment of the present invention will be described. 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

150 g of CMC (manufacturer: Dicell trade name: 1380) powder was added to 1000 ml of pure water having a pH of about 7, while stirring, and the stirring was continued until no precipitate was formed at room temperature. Prepared. This aqueous solution was left at room temperature for about 3 hours. Next, this 1.5 mass% CMC aqueous solution was added to 100 g of crystalline graphite (manufacturer: Nippon Carbon Co., Ltd., brand name: P15B-HG) three times, and mixed uniformly, stirring with 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, 1 g of malonic acid was added to the mixture of graphite / SBR binder / CMC and uniformly mixed to prepare a negative electrode active material slurry.

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 7.21 8.39 7.83 Comparative example 5.13 5.37 5.26

Referring to Table 1, the negative electrode prepared according to the Example showed an average adhesive strength of about 7.83 gf / mm, which was about 90% increase compared to its average value of 5.26.gf/mm prepared according to the comparative example.

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.

Claims (16)

Negative electrode plate; And 90 to 98% by mass of the negative electrode active material, 0.8 to 5% by mass of the SBR binder, 0.8 to 5% by mass of a thickener, and 0.01 to 1% by mass of dicarboxylic acid for enhancing the binding force between the negative electrode active material and the binder to the negative electrode plate. And a negative electrode active material layer on the negative electrode plate. The negative electrode of claim 1, wherein the dicarboxylic acid is C2 to C20 alkane dicarboxylic acid, C4 to C20 alkene dicarboxylic acid, or a combination thereof. The negative electrode of claim 2, wherein the C2 to C20 alkane dicarboxylic acid or C4 to C20 alkene dicarboxylic acid is malonic acid, maleic acid, fumaric acid or a combination thereof. The negative electrode of claim 1, wherein the thickener is selected from the group consisting of carboxy methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. The negative electrode of claim 1, wherein the negative electrode plate is copper or a copper-based alloy. The negative electrode of claim 1, wherein the negative electrode active material comprises a carbon material composed of natural graphite, artificial graphite, graphitizable carbon, non-graphitizable carbon, or a combination thereof. A negative electrode composed mainly of a carbon material; A positive electrode composed of a compound capable of occluding and releasing lithium; A separator interposed between the positive electrode and the negative electrode; And An electrolyte solution in which an electrolyte solute is dissolved in a non-aqueous solvent, The negative electrode is a negative electrode active material layer including a negative electrode active material containing the carbon material as a main material is laminated on a negative electrode plate, the negative electrode active material layer is a negative active material 90 ~ 98 mass%, SBR binder 0.8 ~ 5 mass%, A lithium battery comprising 0.8 to 5% by mass of a thickener, and 0.01 to 1% by mass of dicarboxylic acid for enhancing the bonding strength of the negative electrode active material and the binder to the negative electrode plate. The lithium battery according to claim 7, wherein the dicarboxylic acid is C2 to C20 alkane dicarboxylic acid, C4 to C20 alkene dicarboxylic acid or a combination thereof. The lithium battery according to claim 8, wherein the C2 to C20 alkane dicarboxylic acid or C4 to C20 alkene dicarboxylic acid is malonic acid, maleic acid, fumaric acid or a combination thereof. The lithium battery according to claim 7, wherein the thickener is selected from the group consisting of carboxy methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. The lithium battery according to claim 7, wherein the negative electrode plate is copper or a copper-based alloy. The lithium battery according to claim 7, wherein the negative electrode active material comprises a carbon material composed of natural graphite, artificial graphite, graphitized carbon, non-graphitized carbon, or a combination thereof. The 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 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 -20-80% 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 lithium battery further comprising at least one low boiling point solvent selected from the group consisting of triglyme, tetraglyme, fluorobenzene, and difluorobenzene.