KR101613772B1 - Complex for negative electrode active material and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a composite for a negative electrode active material and a method for producing the same, and more particularly, to a composite for a negative electrode active material comprising a (pseudo) metal oxide and a (pseudomorphic) And physically bonding and dispersing the point-like conductive material on the surface of the composite material.

Description

[0001] The present invention relates to a composite material for an anode active material,

The present invention relates to a composite body for a negative electrode active material in which a point conductive material is bonded to the surface of a negative active material, and a method for manufacturing the same.

With the development of portable electronic devices, a high capacity battery is continuously required. Therefore, studies on high capacity anode active materials such as Sn and Si, which have much higher capacity per unit weight than carbon used as a conventional negative electrode active material, have been actively conducted.

However, when Si or an Si alloy is used as the negative electrode active material, there is a problem that the volume expansion becomes large and the cycle characteristics become poor.

To solve this problem, a negative electrode active material mixed with graphite has been proposed. However, cracks (internal cracks) are generated on the negative active material during charging and discharging, and the electrical conductivity of the negative active material is deteriorated. There is a problem.

Thus, it is necessary to develop a novel negative electrode active material having improved capacity while maintaining uniform electrical conductivity.

The present invention provides a composite for a negative electrode active material capable of preventing a crack generated on a negative electrode active material during charging and discharging and eliminating a decrease in electric conductivity.

In addition, the present invention provides a method for producing the composite for the anode active material.

The present invention also provides a secondary battery having a negative electrode including the composite for the negative electrode active material.

Specifically, in the present invention,

There is provided a composite for a negative electrode active material comprising a (quasi) metal oxide and a point-like conductive material on the surface of the (quasi-) metal oxide.

Further, in one embodiment of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: preparing (sub) metal oxide particles; And dispersing and bonding the point conductive material to the surface of the (quasi-) metal oxide particle to form a composite material for a negative electrode active material.

The present invention also provides a secondary battery having a negative electrode including the composite for the negative electrode active material.

In the present invention, the point conductive material is uniformly dispersed and bonded to the surface of the (quasi-) metal oxide to prevent cracks occurring on the negative electrode active material during charging and discharging and to prevent deterioration of the electrical conductivity of the negative electrode active material, Can be maintained.

1 is a graph showing lifetime characteristics of a battery manufactured according to an experimental example of the present invention.

Hereinafter, the present invention will be described in detail.

Sn and Si-based compounds which are currently used as high-capacity negative electrode active materials are disadvantageous in that their volume expands with the progress of charge and discharge, cracks are generated therein, and the electrical conductivity of the negative electrode active material is lowered.

Accordingly, the present invention provides a composite for a negative electrode active material having improved conductivity while preventing cracks generated in the negative active material during charging and discharging.

Specifically, in one embodiment of the present invention, there is provided a composite for a negative electrode active material in which a point conductive material having a size of several tens of nanometers is dispersed and bonded on the surface of the (sub) metal oxide and the (sub) metal oxide.

In the composite material for the negative electrode active material of the present invention, the (semi) metal oxide is SiO _x, AlO _x, SnO _x, SbO _x, BiO _x, AsO _x, GeO _x, PbO _x, ZnO _x, CdO _x, InO _x , TiO _x and GaO _x (where 0 <x <2), or a mixture of two or more thereof.

In the composite for a negative electrode active material of the present invention, the point conductive material may include at least one selected from the group consisting of carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, have.

At this time, the aspect ratio (the length of the major axis / the length of the minor axis) of the point conductive material may be 1 to 1.5.

The punctiform conductive material may be included in an amount of 1 to 19% by weight based on the total weight of the composite material for the anode active material. If the content of the active material is less than 1% by weight, the effect of improving the electrical conductivity may be insufficient. If the content of the active material is more than 19% by weight, .

The point conductive material may be bonded to the surface of the (sub) metal oxide by physical (e.g., electrostatic attraction force). The composite for a negative electrode active material is not a form in which a (quasi-) metal oxide and a point-type conductive material are bonded by a binder or the like and a surface of a (quasi-) metal oxide is coated with a point-like carbon material. &Lt; / RTI &gt; and evenly dispersed. At this time, the spacing distance between the dispersed conductive materials is not limited, and may be uniform or non-uniform.

In one embodiment of the present invention, the composite for a negative electrode active material may further include a negative electrode active material containing a point conductive material on the surface of the (quasi-) metal oxide and the (quasi-) metal oxide, After composite preparation, the carbonaceous material may be further mixed.

The carbon material may include graphite. Examples of the carbon material include softened carbon, cured carbon, natural graphite, artificial graphite, kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber, carbon microspheres, Pitch, petroleum coke, and coal-based coke, but the present invention is not limited thereto.

The carbon material may be included in an amount of 20 to 80 parts by weight based on 100 parts by weight of the negative electrode active material. When the carbon material is outside the above range, the effect of dispersing the point conductive material in the (sub) metal oxide and selectively imparting electrical conductivity may be insignificant.

As described above, in the present invention, by dispersing the point conductive material on the surface of the (quasi-) metal oxide and physically bonding it to each other, it is possible to prevent the electrical conductivity of the negative active material from being lowered due to cracking, Lt; / RTI &gt;

In another embodiment of the present invention,

Preparing a (sub) metal oxide particle; And

And dispersing and bonding the point conductive material to the surface of the (quasi) metal oxide particle to form a composite material for a negative electrode active material.

At this time, the method of the present invention may further include a step of mixing the carbonaceous material after manufacturing the composite for the anode active material.

In the method for manufacturing a composite for a negative electrode active material according to the present invention, a NOBILTA device (NOBILTA, manufactured by Hosokawa) or a Mechano fusion device is used to disperse and physically bond the point conductive material to the surface of the (quasi-) metal oxide . The NOBILTA device can physically bond and disperse the point-like conductive material to the (quasi) metal oxide surface using only mechanical force, without additional material such as a binder, in the dry state of the solid (quasi) metal oxide and the point conductive material . The Mechano fusion device may be performed using a high energy ball mill, a planetary mill, a stirred ball mill, a vibrating mill, or the like, But is not limited thereto.

The physical bonding and dispersion of the point conductive material and the (quasi-) metal oxide may be performed at room temperature for 1 to 60 minutes at a rotation speed of 1300 to 1700 rpm.

Also, when the mechano fusion device is used, the weight of the ball may be 10 to 20, assuming that the weight of the (sub) metal oxide and the point conductive material is 1. [ If it is out of the above range, compressive stress can not be applied to the (quasi-) metal oxide and the point conductive material, and if unnecessary ball is used, it may be inefficient in terms of energy efficiency. The ball may be of stainless steel or zirconia material, and the diameter of the ball may be 0.1 to 10 mm.

At this time, the average particle diameter of the (sub) metal oxide and the point conductive material is not particularly limited, but a material having a small particle diameter may be used in order to shorten the mixing time and the mechanical alloying treatment time.

In addition, in the method for producing a composite for a negative electrode active material according to an embodiment of the present invention, the point conductive agent and the (quasi-) metal oxide may be combined with each other in a weight ratio of 1 to 19:81 to 99 for the same reason as the content range of the above- To form a complex.

In an embodiment of the present invention,

A cathode comprising a cathode active material; A negative electrode comprising a composite for a negative electrode active material comprising a (quasi) metal oxide and a point-like conductive material on a surface of the (quasi-) metal oxide; A separator, and an electrolyte.

At this time, the composite for a negative electrode active material of the present invention may further include a carbonaceous material.

The secondary battery according to an embodiment of the present invention includes a negative electrode active material including a pseudo-metal oxide and a pseudo-conductive material on the surface of the (quasi-) metal oxide, Cracks (internal cracks) are generated in the negative electrode active material due to the combined and dispersed charge and discharge processes, thereby preventing the deterioration of the electrical conductivity of the negative electrode active material, thereby maintaining the performance of the secondary battery.

The negative electrode is prepared, for example, by coating a negative electrode current collector with a mixture of a negative electrode active material, a conductive material and a binder, followed by drying. If necessary, a filler may be further added. The anode can also be manufactured by applying a cathode active material on a cathode current collector and drying the cathode active material.

The separation membrane is interposed between the cathode and the anode, and an insulating thin film having high ion permeability and mechanical strength is used. The current collector, the electrode active material, the conductive material, the binder, the filler, the separator, the electrolyte, the lithium salt, and the like are well known in the art, and a detailed description thereof will be omitted herein.

A battery current collector is formed with a separator interposed between the positive electrode and the negative electrode. The battery current collector is wound or folded into a cylindrical battery case or a prismatic battery case, and then an electrolyte is injected to complete the secondary battery. Alternatively, the battery current collector may be laminated in a bi-cellular structure, then impregnated with an electrolyte, and the resulting product is sealed in a pouch to complete the secondary battery.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

Example

(Example 1: Production of composite for negative electrode active material 1)

95% by weight of SiO 2 (quasi) metal oxide and 5% by weight of carbon black as a point conductive material were placed in a NOBILTA apparatus and mixed at a rotational speed of 1,500 rpm at room temperature for 10 minutes so that the point conductive material was physically bonded to the SiO 2 surface, To prepare a composite for an active material.

(Example 2: Production of composite for negative electrode active material 2)

The mixture for anode active material was prepared in the same manner as in Example 1 except that the mixture was mixed at a rotational speed of 1500 rpm for 20 minutes.

(Example 3: Production of composite for negative electrode active material 3)

The mixture for negative electrode active material was prepared in the same manner as in Example 1 except that the mixture was mixed at a rotation speed of 1500 rpm for 30 minutes.

(Example 4: Production of composite for negative electrode active material 3)

95% by weight of SiO 2 (quasi) metal oxide and 5% by weight of carbon black as a point conductive material were placed in a NOBILTA apparatus and mixed at a rotational speed of 1,500 rpm at room temperature for 10 minutes so that the point conductive material was physically bonded to the SiO 2 surface, To prepare a composite for an active material.

Next, 40% by weight of graphite, which is a carbon material, was mixed with the negative electrode active material composite to prepare a composite for a negative electrode active material in which a carbon material was further combined.

(Example 5)

LiCoO ₂ as a cathode active material, artificial graphite as a conductive agent, and polyvinylidene fluoride as a binder were mixed in a weight ratio of 94: 3: 3, followed by addition of N-methylpyrrolidone to prepare a slurry. The slurry thus prepared was applied to an aluminum foil and dried at 130 DEG C for 2 hours to prepare a positive electrode.

A slurry was prepared by mixing the negative active material composite of Example 1 and a binder (styrene butadiene rubber) in a weight ratio of 97: 3 and adding N-methyl pyrrolidone. The prepared slurry was applied to a copper foil and dried at 130 캜 for 2 hours to prepare a negative electrode.

A polyethylene separator was inserted between the negative electrode and the positive electrode plate, inserted into a battery case, and then an electrolyte solution was injected to assemble the coin cell battery. At this time, a mixed solution of ethylene carbonate / ethylmethyl carbonate and diethyl carbonate (1/2/1 by volume) in which 1.0 M LiPF ₆ was dissolved was used as an electrolyte solution.

(Example 6)

A negative electrode, a positive electrode and a battery including the same were prepared in the same manner as in Example 5 except that the composite for negative active material of Example 2 was used instead of the composite for negative active material of Example 1 above.

(Example 7)

A negative electrode, a positive electrode, and a battery including the same were prepared in the same manner as in Example 5 except that the composite for negative active material of Example 3 was used instead of the composite for negative active material of Example 1 above.

(Example 8)

A negative electrode, a positive electrode and a battery including the same were prepared in the same manner as in Example 5 except that the composite for negative active material of Example 4 was used instead of the composite for negative active material of Example 1 above.

(Comparative Example 1)

A negative electrode active material (artificial graphite), a conductive material (Super-P) and a binder (styrene butadiene rubber) were mixed at a weight ratio of 94: 3: 3 and N-methylpyrrolidone was added to prepare a slurry. The prepared slurry was applied to a copper foil and dried at 130 캜 for 2 hours to prepare a negative electrode.

LiCoO ₂ as a cathode active material, artificial graphite as a conductive agent, and polyvinylidene fluoride as a binder were mixed in a weight ratio of 94: 3: 3, followed by addition of N-methylpyrrolidone to prepare a slurry. The slurry thus prepared was applied to an aluminum foil and dried at 130 DEG C for 2 hours to prepare a positive electrode.

A polyethylene separator was inserted between the negative electrode and the positive electrode plate, inserted into a battery case, and then an electrolyte solution was injected to assemble the coin cell battery. At this time, a mixed solution of ethylene carbonate / ethylmethyl carbonate and diethyl carbonate (1/2/1 by volume) in which 1.0 M LiPF ₆ was dissolved was used as an electrolyte solution.

(Experimental Example 1 Life characteristics)

The charge and discharge life characteristics of the battery prepared in Example 5 and Comparative Example 1 were measured at 0.7 C-rate, and the results are shown in FIG.

1, the battery of Example 5 including the negative electrode active material composite of the present invention exhibited excellent battery life characteristics, while the battery of Comparative Example 1 exhibited a deterioration in life characteristics.

Therefore, it can be seen that the battery of Example 5 including the negative electrode active material composite according to the present invention has improved cycle characteristics as compared with the battery of Comparative Example 1. [

Claims (16)

(Quasi-) metal oxide and a point-like conductive material on the surface of the (quasi-) metal oxide,
The point conductive material is 1 to 19% by weight based on the total weight of the composite material for a negative electrode active material,
Wherein the aspect ratio of the spot-like conductive material is 1 to 1.5. The method according to claim 1,
The (semi) metal oxide is SiO _x, AlO _x, SnO _x, SbO _x, BiO _x, AsO _x, GeO _x, PbO _x, ZnO _x, CdO _x, InO _x, TiO _x, and GaO _x (wherein, 0 < x < 2), or a mixture of two or more thereof. The method according to claim 1,
Wherein the spot-type conductive material comprises a single material selected from the group consisting of carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black, or a mixture of two or more thereof. The method according to claim 1,
Wherein the spot-like conductive material is uniformly dispersed and physically bonded to the surface of the (quasi) metal oxide. delete delete A composite for a negative electrode active material further comprising a composite for a negative electrode active material according to claim 1 and a carbonaceous material. The method of claim 7,
The carbon material is selected from the group consisting of softened carbon, cured carbon, natural graphite, artificial graphite, kish graphite, pyrolytic carbon, liquid crystal pitch-based carbon fiber, carbon microspheres, liquid crystal pitch, petroleum coke and coal coke A composite for a negative electrode active material, comprising a single material or a mixture of two or more materials. The method of claim 7,
Wherein the carbon material is included in an amount of 20 to 80 parts by weight based on 100 parts by weight of the negative electrode active material. A negative electrode active material comprising the negative electrode active material composite according to claim 1. The negative electrode active material according to claim 7, comprising a composite for a negative electrode active material. Preparing a (sub) metal oxide particle; And
Dispersing and bonding the point conductive material to the surface of the (quasi) metal oxide particle,
Wherein the aspect ratio of the pointed conductive material is from 1 to 1.5,
Wherein the spot-like conductive material and the (quasi-) metal oxide are bonded at a weight ratio of 1 to 19: 81 to 99. The method of claim 12,
Wherein the dispersion and the physical coupling are performed at 1300 to 1700 rpm for 1 to 60 minutes. The method of claim 12,
Wherein the method further comprises mixing the carbonaceous material composite with the carbonaceous material composite. A cathode comprising a cathode active material;
An anode including the anode active material of claim 10;
A separator interposed between the anode and the cathode; And
Wherein the secondary battery comprises an electrolyte. A cathode comprising a cathode active material;
A negative electrode comprising the negative electrode active material of claim 11;
A separator interposed between the anode and the cathode; And
Wherein the secondary battery comprises an electrolyte.

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