KR101664811B1 - Anode slurry for lithium-ion battery, and lithium-ion battery having the anode slurry - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative electrode material mixture for a lithium ion secondary battery, a method for producing the same, and a lithium ion secondary battery having the same. More specifically, the present invention relates to a negative electrode material mixture for a lithium ion secondary battery, To provide a binder comprising a material comprising a dicarboxylic acid to improve process characteristics while achieving uniform electrode density by improving sedimentation characteristics in which solids are separated in a solvent as well as preventing or inhibiting , A negative electrode material mixture for a lithium ion secondary battery includes a binder containing a dicarboxylic acid, an active material containing silicon, a conductive agent for increasing the conductivity of the active material, and a solvent.

Description

TECHNICAL FIELD [0001] The present invention relates to a negative electrode material for a lithium ion secondary battery, and a lithium ion secondary battery having the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to an anode mix for a lithium ion secondary battery and a lithium ion secondary battery having the same. More particularly, the present invention relates to a lithium ion secondary battery for preventing or suppressing peeling due to volume expansion and contraction of a negative electrode of a lithium- In addition, a lithium ion secondary battery including a binder containing a substance including a dicarboxylic acid for improving process characteristics while improving uniformity of electrode density by improving sedimentation property in which solid matters are separated in a solvent A negative electrode material mixture and a lithium ion secondary battery having the same.

Lithium ion secondary batteries are one of the energy storage devices that store energy.

The lithium ion secondary battery has a higher energy density than the nickel cadmium battery, has no memory effect, is environmentally friendly, has a long life cycle, can output a high voltage, and can be miniaturized Recently, it is widely used in small portable electronic products such as mobile phones, tablet PCs and camcorders.

Conventional lithium ion secondary batteries include a positive electrode, a negative electrode, a separator, and an electrolytic solution as main components.

Conventionally, a cathode of a lithium ion secondary battery includes lithium oxide, and a cathode includes a carbon compound such as graphite capable of storing lithium ions. The separator prevents direct contact between the anode and the cathode, And serves as a medium for allowing lithium ions to move.

Recently, a technique for increasing the reversible capacity of a lithium ion secondary battery by changing a negative electrode material of a lithium ion secondary battery from a carbon-based material to a silicon-based material has been studied.

However, when the anode material of the lithium ion secondary battery is changed from the carbon material to the silicon material, the reversible capacity of the lithium ion secondary battery having a silicon-based negative electrode can be greatly increased. On the other hand, Deterioration of the electrode due to volume expansion and contraction of the material, and peeling of the binder of the silicon-based material from the negative electrode, thereby significantly shortening the battery life.

In order to solve the problem caused by employing the silicon-based negative electrode of such a lithium ion secondary battery, Korean Unexamined Patent Publication No. 2007-0110569, published on November 20, 2007, discloses a binder containing polyacrylic acid physically mixed with polyurethane And a lithium secondary battery based thereon disclose a binder in which polyurethane is physically mixed with polyacrylic acid.

In order to solve the problems caused by employing a silicon-based negative electrode of a lithium ion secondary battery, Korean Unexamined Patent Publication No. 2014-0012464, published on Feb. 3, 2014, a silicon alloy based negative electrode active material, an anode active material composition containing the same, A manufacturing method thereof and a technique in which an organic binder including a polyamideimide is used for a lithium secondary battery are disclosed.

When a negative electrode material mixture is prepared by using a binder, a silicon-based active material, a conductive material, and a solvent having polyacrylic acid as a binder of a silicon-based negative electrode of a lithium ion secondary battery, the solubility of a solid component including a silicon-based active material, And when the negative electrode mixture having the settling phenomenon is applied to the negative electrode, the electrode density of the negative electrode becomes uneven.

Korean Patent Publication No. 2007-0110569, an electrode mixture containing polyacrylic acid physically mixed with polyurethane as a binder, and a lithium secondary battery based thereon (2007. 11. 20) Korean Unexamined Patent Publication No. 2014-0012464, a silicon alloy-based negative electrode active material, a negative electrode active material composition containing the same, a manufacturing method thereof, and a lithium secondary battery (Apr.

Disclosure of Invention Technical Problem [10] The present invention relates to a silicone-based negative electrode material mixture which prevents deterioration of the battery life due to volumetric expansion and contraction due to charging and discharging, prevents sedimentation of solid components, uniformly distributes the negative electrode material mixture to a negative electrode, , An excellent recovery rate, and an excellent rigidity, a method for producing the same, and a lithium ion secondary battery having the same.

In one embodiment, the anode mix for a lithium ion secondary battery includes a binder containing a dicarboxylic acid, an active material containing silicon, a conductive agent for increasing the conductivity of the active material, and a solvent.

The binder of the negative electrode mixture for a lithium ion secondary battery includes poly (maleic acid) (PMA).

The binder of the negative electrode mixture for a lithium ion secondary battery includes a first binder containing poly (maleic acid) (PMA) and a first synthetic binder synthesizing a second binder.

The second binder of the negative electrode material mixture for a lithium ion secondary battery is selected from the group consisting of polyacrylic acid (PAA), poly (aryl ether ketone), poly (arylamide), aromatic polyimide, aromatic poly Aromatic poly (phenylene sulfide) based, aromatic polyphosphazene, and aromatic poly (arylene sulfide), based on the total weight of the aromatic poly (arylene ether), poly Modified polystyrenes, and modified polystyrenes of these polymers.

The binder of the negative electrode material mixture for a lithium ion secondary battery includes a second synthetic binder chemically synthesized with the third binder.

The third binder of the negative electrode material mixture for a lithium ion secondary battery may be at least one selected from the group consisting of polyacrylic acid (PAA), poly (aryl ether ketone), poly (arylamide), aromatic polyimide, Aromatic poly (phenylene sulfide) based, aromatic polyphosphazene, and aromatic poly (arylene sulfide), based on the total weight of the aromatic poly (arylene ether), poly Modified polystyrenes, and modified polystyrenes of these polymers.

A method for producing a negative electrode mixture of a lithium ion secondary battery includes the steps of: dissolving a first binder containing a carboxylic acid (-COOH) in a solvent; Providing a second binder comprising a dicarboxylic acid in the solvent in which the first binder is dissolved; And synthesizing a synthetic binder by providing a reaction inducing agent for inducing a reaction of the first and second binders to the solvent.

In the method for manufacturing a negative electrode mixture of a lithium ion secondary battery, the first binder includes polyacrylic acid (PAA), and the second binder includes poly (maleic acid) (PMA). do.

A lithium ion secondary battery includes a cathode having a cathode coated with a cathode mixture containing a cathode active material, a conductive agent, and a binder, a cathode separated from the cathode, and a cathode mixture coated with a cathode active material, a conductive agent, and a binder; A separator separating the anode and the cathode; And an electrolyte solution for ion transfer between the anode and the cathode, wherein the binder contained in the negative electrode mixture includes a first binder including a carboxylic acid (-COOH) and a second binder including a dicarboxylic acid And synthetic binders chemically synthesized.

The first binder of the lithium ion secondary battery includes polyacrylic acid (PAA), and the second binder includes poly (maleic acid) (PMA).

A binder for a lithium ion secondary battery, a method for producing the same, and a lithium ion secondary battery having the same according to the present invention suppress the volume expansion and contraction due to charging / discharging caused by using a negative electrode mixture containing silicon to increase the capacity, It is possible to prevent the reduction of the lifetime and to prevent the settling phenomenon of the solid component to uniformly distribute the negative electrode mixture to the electrode so as to uniformly form the electrode density and to have an excellent binding force with respect to the conventional binder and excellent recovery rate and excellent rigidity, Greatly improves.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a chemical formula of a binder included in an anode mix according to an embodiment of the present invention; FIG.
Fig. 2 is a chemical formula of the first synthetic binder using the binder of Fig. 1; Fig.
3 is a view showing a process of synthesizing a second synthetic binder using the first synthetic binder of FIG.
4 is a flowchart showing a process of manufacturing the second synthetic binder shown in FIG.
FIG. 5 is a cross-sectional view conceptually showing a lithium ion secondary battery including a negative electrode coated with a negative electrode mixture including the second synthetic binder shown in FIG. 3;
FIGS. 6 and 7 are SEM photographs of the cracks generated after charge and discharge of the lithium ion secondary cell shown in FIG. 5. FIG.
8 is a graph showing the electrochemical evaluation results of Table 2.
9 is a graph showing the comparative example according to charging / discharging and the holding capacity in the embodiment.

In the following description, only parts necessary for understanding the embodiments of the present invention will be described, and the description of other parts will be omitted so as not to obscure the gist of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and the inventor is not limited to the meaning of the terms in order to describe his invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention, so that various equivalents And variations are possible.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a chemical formula of a binder included in an anode mix according to an embodiment of the present invention; FIG.

Referring to FIG. 1, a negative electrode material mixture of a lithium ion secondary battery may include a binder 100, an active material, a conductive agent, and a solvent.

In one embodiment of the present invention, the active material used in the negative electrode mixture of the lithium ion secondary battery reversibly absorbs or discharges lithium ions supplied from the positive electrode of the lithium ion secondary battery while allowing electrons (current) .

In one embodiment of the present invention, the active material contained in the negative electrode material mixture of the lithium ion secondary battery includes silicon and graphite, and the active material contained in the negative electrode material mixture includes silicon and graphite, for example, 3: 7 Mixing ratio.

The conductive agent serves to improve the conductivity of the active material contained in the negative electrode mixture, and the solvent has a form of a slurry suitable for being applied to the negative electrode by mixing the binder, the active material and the conductive agent contained in the negative electrode mixture at a uniform density.

When the active material contained in the negative electrode mixture of the lithium ion secondary battery contains silicon, the lithium ion secondary battery has a very high theoretical capacity and reversible capacity as compared with the active material containing only graphite.

However, when the active material contained in the negative electrode material mixture of the lithium ion secondary battery contains silicon, the theoretical capacity and the reversible capacity are dramatically increased, while the negative electrode material mixture expands or shrinks during charging or discharging of the lithium ion secondary battery do. In the case of a negative electrode mixture containing an active material containing silicon, a volume expansion or contraction of about 400% or more occurs during charging or discharging.

Cracks or tears are generated on the surface of the negative electrode mixture when excessive volume expansion or volume shrinkage occurs in the negative electrode mixture containing the active material containing silicon upon charging or discharging.

Also, as the charging or discharging is repeated, the negative electrode mixture is repeatedly expanded or contracted, and the negative electrode mixture is separated or eliminated from the negative electrode, so that the lifetime of the lithium ion secondary battery is greatly shortened and the performance of the lithium ion secondary battery is greatly reduced.

In an embodiment of the present invention, the binder 100 is used to prevent cracks, tearing, peeling, and tearing of the negative electrode mixture in a lithium ion battery including an active material containing silicon.

In one embodiment of the present invention, the binder 100 is used in combination with a silicon-containing active material in the negative mixture to prevent cracking, tearing, peeling, and tearing of the negative mixture, A dicarboxylic acid, and a dicarboxylic acid-containing chemical may include poly (maleic acid) (PMA).

In one embodiment of the present invention, the binder 100 may be used by using polymaleic acid (PMA) alone or by mixing or polymerizing polymaleic acid (PMA) with other chemicals.

When the binder 100 containing polyamic acid (PMA) is mixed with the negative electrode mixture of the lithium ion secondary battery, the solid component is prevented from being separated (settled) in the solvent so that the negative electrode mixture is adhered to the negative electrode of the lithium ion secondary battery A very uniform electrode density can be realized in the anode mixture when formed.

Fig. 2 is a chemical formula of the first synthetic binder using the binder of Fig. 1; Fig.

Referring to FIG. 2, the first synthetic binder 200 forming the negative electrode mixture of the lithium ion secondary battery includes a first binder 210 and a second binder 220, 1 binder 210 and the second binder 220 are combined.

In one embodiment of the present invention, the first binder 210 comprises a dicarboxylic acid comprising at least two carboxy groups and the chemical comprising a dicarboxylic acid may be a poly (maleic acid, PMA).

The second binder 220 may include polyacrylic acid (PAA) containing a carboxyl group.

A negative electrode mixture containing a first synthetic binder 200 synthesized with polyacrylic acid (PAA) which is a second binder 220 synthesized with polyamic acid (PMA) as a first binder 210 is applied to a negative electrode The sintering temperature can be lowered when the sintering is performed, and the process characteristics can be greatly improved.

In one embodiment of the present invention, the second binder 220 to be combined with the polyamine acid (PMA) as the first binder 210 may be poly (aryl ether ketone) based, poly (arylamide) Aromatic polyimide, aromatic polyimide, aromatic poly (amide-imide), aromatic polyurethane, aromatic polyester (polyarylate), polybenzimidazole, polybenzoxazole, aromatic polysulfone, aromatic poly Ether sulfone), aromatic poly (phenylene sulfide), aromatic polyphosphazene, and modified polymers of these polymers.

In this way, the first composite binder 200 formed by synthesizing the first binder 210 and the second binder 220 is mixed with an active material including silicon and graphite, a conductive agent for improving the conductivity of the active material, (Precipitate) of the solid material including the active material, the conductive agent, and the first synthetic binder in the solvent from the solvent, so that when the negative electrode material mixture is formed on the negative electrode of the lithium ion secondary battery, The sintering temperature of the negative electrode mixture can be greatly reduced by polyacrylic acid (PAA), which is the second binder 220 included in the first synthetic binder 200, and the process characteristics can be improved.

Fig. 3 is a chemical formula of a second synthetic binder using the binder of Fig. 2; Fig.

Referring to FIG. 3, the second synthetic binder 300 forming the negative electrode mixture of the lithium ion secondary battery is formed by synthesizing the first synthetic binder 325 and the third binder 230.

The second synthetic binder 200 is formed by synthesizing the first binder 310 and the second binder 320 as shown in FIG.

In one embodiment of the present invention, the first binder 310 comprises a dicarboxylic acid comprising at least two carboxy groups and the chemical comprising a dicarboxylic acid may be a poly (maleic acid, PMA).

The second binder 320 may include, for example, polyacrylic acid (PAA) containing a carboxyl group.

A first binder 310 containing polyamic acid (PMA) and a first synthetic binder 325 synthesizing polyacrylic acid (PAA) which is a second binder 320 synthesized with the first binder 310 The third binder 330 is synthesized with the first synthetic binder 325 to form the second synthetic binder 300.

In one embodiment of the present invention, the third binder 330 combined with the first composite binder 325 may be polyacrylic acid (PAA). Examples of the third binder 330 that can be used as the third binder 330 include poly (aryl ether ketone) based, poly (arylamide) based, aromatic polyimide based, aromatic poly (amide-imide) based, Aromatic poly (phenylene sulfide) based, aromatic polyphosphazene, and aromatic poly (arylene sulfide), based on the total weight of the aromatic poly (arylene ether), poly Modified polystyrenes, and modified polystyrenes of these polymers.

As described above, the second synthetic binder 300 formed by synthesizing the first synthetic binder 325 and the third binder 330 is mixed with an active material including silicon and graphite, a conductive agent for improving the conductivity of the active material, When the negative electrode material mixture is formed on the negative electrode of the lithium ion secondary battery, it is possible to prevent the solid material including the active material, the conductive agent and the second synthetic binder from being separated (precipitated) from the solvent in the solvent, Not only the electrode density can be realized but also the sintering temperature of the negative electrode mixture is greatly reduced by the polyacrylic acid (PAA) which is the third binder 330 included in the second synthetic binder 300, thereby improving the process characteristics.

Hereinafter, with reference to Table 1, the sedimentation solids in the negative electrode mixture including polyacrylic acid (PAA), the first synthetic binder and the second synthetic binder were compared to find that the binder containing polyacrylic acid (PAA) The performance of the binder and the second synthetic binder will be described.

Polyacrylic acid (PAA) The first synthetic binder The second synthetic binder Settled solid content (%) 20% 2.3% 3.8%

Referring to Table 1, when the binder using polyacrylic acid (PAA) alone is applied to the negative electrode mixture, the settling rate at which the active material, the conductive agent and the binder contained in the negative electrode mixture are separated (settled) in the solvent is It was about 20%.

On the other hand, in the case of the negative electrode mixture using the first synthetic binder 325, the sedimentation rate at which the active material, the conductive agent, and the binder contained in the negative electrode mixture were separated (precipitated) in the solvent was about 2.3%.

In the case of the negative electrode mixture using the second composite binder 300, the sedimentation rate at which the active material, the conductive agent, and the binder contained in the negative electrode mixture were separated (settled) in the solvent was about 3.8%.

As a result, in the case of the first synthetic binder 325 or the second synthetic binder 3.8, the sedimentation rate was very low as compared with the binder using polyacrylic acid (PAA) alone. As a result, So that a very uniform electrode density can be realized.

4 is a flowchart illustrating a process of manufacturing a synthetic binder included in a negative electrode material mixture according to an embodiment of the present invention. In one embodiment of the present invention, the synthetic binder process shown in FIG. 4 will be described as an example of a process for forming the synthetic binder shown in FIG.

4, in order to produce the second synthetic binder 300, a third binder 330 of A [g] is provided in water and the third binder 330 is dissolved in water (step S10)

In one embodiment of the present invention, the third binder 330 may comprise polyacrylic acid (PAA). Alternatively, the third binder 330 may be a poly (aryl ether ketone) based, a poly (aryl amide) based, an aromatic polyimide based, an aromatic poly (amide-imide) based, an aromatic polyurethane based, Aromatic poly (phenylene sulfide) system, aromatic polyphosphazene, and modified polymers of these polymers, as well as polyesters, such as polystyrenes, polybenzimidazole, polybenzoxazole, aromatic polysulfone, And the like.

After the third binder 330 is dissolved in the solvent, the solvent in which the third binder 330 is dissolved is provided with the first synthetic binder 325 shown in Fig. 3B [g].

The first synthetic binder 325 is formed by synthesizing the first binder 310 and the second binder 320. The first binder 310 included in the first synthetic binder 325 is formed by combining poly (PMA), and the second binder 320 comprises polyacrylic acid (PAA) to improve process characteristics.

In an embodiment of the present invention, the second binder 320 may be a poly (aryl ether ketone) based, a poly (arylamide) based, an aromatic polyimide based, an aromatic poly (amide- imide) based, an aromatic polyurethane based, Aromatic polyphosphazenes, aromatic polyphosphazenes, aromatic polyphosphazenes, aromatic polyphosphazenes, aromatic polyphosphazenes, aromatic polyphosphazenes, aromatic polyphosphazenes, aromatic polyphosphazenes, aromatic polyphosphazenes, Modified water, and the like.

Next, C [g] is added to induce reaction period of the third binder 300 and the first synthetic binder 325 in the operating period (step S30). (Step S30)

In one embodiment of the present invention, the reaction inducing agent may be, for example, sulfuric acid, and the ratio of the third binder 330, the first synthetic binder 325, and the reaction inducing agent may be 1: 1: 0.02. For example, when the third binder 330 is about 10 [g], the first synthetic binder 325 may be about 10 [g] and the reaction inducing agent may be about 0.2 [g].

After the third binder 300, the first synthetic binder 325 and sulfuric acid as a reaction inducing agent are added to the solvent, the mixed solution is stirred for 24 hours under reflux conditions (Step S40)

After the third binder 330, the first synthetic binder 325, and the reaction inducing agent are dissolved in water and then stirred to produce the second synthetic binder 300, the second synthetic binder 300 may not participate in producing the second synthetic binder 300 The unreacted third binder 330 and the first synthetic binder 325 are filtered and removed from the second synthetic binder 300 and the remaining water is also removed using a pressurized distillation apparatus.

Subsequently, a trace amount of impurities that can be formed during the synthesis of the second synthetic binder 300 is removed by decantation a plurality of times with ethyl acetate and diethyl ether.

Thereafter, the unreacted material and the second binder binder 300 remaining after the third binder 330, the first binder 325, the solvent, and the impurities are removed are dried under vacuum for 24 hours (Step S50) 2 composite binder 300 is produced.

FIG. 5 is a cross-sectional view conceptually showing a lithium ion secondary battery including a negative electrode coated with a negative electrode mixture containing the synthetic binder shown in FIG. 3. FIG.

The lithium ion secondary battery 500 includes a cathode 510, a cathode 520, a separator 530, and an electrolyte 540.

The anode 510 includes an anode electrode 511 and a cathode mixture 515.

The positive electrode mixture 515 includes a positive electrode active material containing lithium oxide, a conductive agent for improving the conductivity of the positive electrode active material, and a second synthetic binder 300 shown in FIG. 3. The positive electrode mixture 515 includes an anode electrode 511 Or the like.

The cathode 520 includes a cathode electrode 521 and a cathode mixture 525.

The negative electrode 521 is disposed apart from the positive electrode 511. The negative electrode mixture 525 is composed of a negative electrode active material mixed with silicon and graphite in a ratio of 3: 7, a conductive agent for improving the conductivity of the negative electrode active material, For example, the second synthetic binder 300 shown in Fig.

In one embodiment of the present invention, the active material contained in the negative electrode mixture 525, the second synthetic binder 300, and the conductive agent are prepared at a ratio of 8: 1: 1. The cathode mixture 525 is applied and formed on the surface of the cathode electrode 511. [

The separation membrane 530 has a structure having pores through which the electrolytic solution passes. For example, PE (poly (ethylene) is used as the separation membrane.

The electrolyte solution 540 contains EC: EMC in a ratio of 1: 2, and the electrolyte solution 540 includes 1M LiPF ₆ and 10% F-EC.

In an embodiment of the present invention, the second synthetic binder 300 included in the negative electrode mixture 525 includes a third binder 330 including polyacrylic acid (PAA) as shown in FIG. 3, The first synthetic binder 325 is formed by synthesizing a first binder 310 containing polyamic acid (PMA) d and a second binder 320 including polyacrylic acid (PAA) .

6 is a SEM photograph of a crack generated after charge and discharge of a lithium ion secondary battery including a binder containing polyacrylic acid according to a comparative example.

Referring to FIG. 6, when charging or discharging the lithium ion secondary battery in the state where polyacrylic acid (PAA) is contained in the binder included in the negative electrode mixture mixed with the negative electrode of the lithium ion secondary battery, It was observed that very large size cracks were generated. When the volume expansion or contraction of the negative electrode mixture is not controlled, the charging or discharging of the lithium ion secondary battery is repeated so that the negative electrode mixture tears or tears from the negative electrode.

FIG. 7 is a SEM photograph of a crack after charging / discharging of a lithium ion secondary battery including a negative electrode material mixture containing the second synthetic binder shown in FIG. 3; FIG.

Referring to FIG. 7, when the lithium ion secondary battery is charged or discharged in a state where the second synthetic binder (PAA-PAA / PMA) is included in the binder included in the negative electrode mixture to be applied to the negative electrode of the lithium ion secondary battery, It was observed that the second synthetic binder controlled the volume expansion or shrinkage of the mixture to generate a very small-sized crack as compared with the crack shown in Fig. By controlling the volume expansion or contraction of the negative electrode mixture in this manner, it is possible to prevent the negative electrode mixture from being torn or separated from the negative electrode even if the charging or discharging of the lithium ion secondary battery is repeated.

[Table 2] discloses electrochemical evaluation results of a lithium ion secondary battery comprising a lithium ion secondary battery including a binder according to a comparative example including polyacrylic acid (PAA) and the second synthetic binder of Fig. 3.

Comparative Example
(PAA) 1st 10th 20th 30th 40th 50th 60th 70th 80th 90th Volume
(mAh / g) 1122.5 1000.3 935.4 894.2 868.5 850.1 834.3 820.6 808.9 798.4 Retention rate
(%) 100 88.6 83.3 79.7 77.4 75.7 74.3 73.1 72.1 71.7 Example
(PAA-PAA / PMA) 1st 10th 20th 30th 40th 50th 60th 70th 80th 90th Volume
(mAh / g) 1291.3 1207.9 1125.5 1069.0 1036.2 1012.2 991.7 974.5 960.8 948.2 Retention rate
(%) 100 92.5 87.2 82.8 80.2 78.4 76.8 75.5 74.4 73.4

FIG. 8 is a graph showing the electrochemical evaluation results of Table 2, and FIG. 9 is a graph showing the comparative example according to charging and discharging and the holding capacity in the embodiment.

Referring to [Table 2], FIG. 8, and FIG. 9, in the case of the lithium ion secondary battery including the second synthetic binder synthesized as the evaluation result in the embodiment, In the case of a lithium ion secondary battery including a binder using polyacrylic acid (PAA), the capacity was 1122.5 [mAh / g] at the time of the first charge. As a result of performing charge and discharge at 90 times, In the case of the lithium ion secondary battery including the second synthetic binder, the capacity was 948.5 [mAh / g]. In the case of the lithium ion secondary battery including the binder using the polyacrylic acid (PAA) according to the comparative example, / g], the capacity of the lithium ion secondary battery including the second synthetic binder was superior to that of the lithium ion secondary battery according to the comparative example.

In terms of the retention rate, the lithium ion secondary battery including the second synthetic binder was tested to have an excellent retention ratio after 90 charge / discharge cycles compared to the lithium ion secondary battery including the binder containing polyacrylic acid, which is a comparative example.

As described above in detail, the use of the negative electrode mixture containing silicon to increase the capacity prevents volume expansion and contraction caused by charging and discharging caused by charging and discharging, thereby preventing a reduction in battery life, It is possible to uniformly distribute the negative electrode mixture to the electrode to uniformly form the electrode density and reduce the sintering temperature of the negative electrode mixture to improve the manufacturing process characteristics, thereby greatly improving the performance of the lithium ion secondary battery.

It should be noted that the embodiments disclosed in the drawings are merely examples of specific examples for the purpose of understanding, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims (10)

A binder including a carboxylic acid and a dicarboxylic acid, an active material including silicon, a conductive agent for increasing the conductivity of the active material, and a solvent,
The binder is a second synthetic binder chemically synthesized with polyacrylic acid (PAA) in a first synthetic binder chemically synthesized with poly (maleic acid) (PMA) and polyacrylic acid (PAA)
Wherein the first synthetic binder prevents sedimentation of the solid material including the active material and the conductive agent contained in the solvent against the solvent and reduces the sintering temperature of the negative electrode material mixture for a lithium ion secondary battery. delete delete delete delete delete delete delete A positive electrode coated with a positive electrode mixture including a positive electrode active material, a conductive agent, and a binder on the positive electrode;
A negative electrode spaced apart from the positive electrode and coated with a negative electrode mixture mixed with a negative electrode active material, a conductive agent, and a binder on the negative electrode;
A separator separating the anode and the cathode;
An electrolyte for ion transfer between the anode and the cathode; / RTI >
Wherein the negative electrode material mixture contains a binder including a carboxylic acid and a dicarboxylic acid, an active material including silicon, a conductive agent for increasing the conductivity of the active material, and a solvent,
The binder contained in the negative electrode material mixture may be a second synthetic resin obtained by chemically synthesizing polyacrylic acid (PAA) in a first synthetic binder chemically synthesized with poly (maleic acid) (PMA) and polyacrylic acid (PAA) Binder,
Wherein the first synthetic binder prevents sediments of the solid material including the active material and the conductive agent contained in the solvent from being settled to the solvent and reduces the sintering temperature. delete

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