KR100771840B1 - Heterogeneous-carbonaceous materials-inserted globule carbonaceous powders and process for preparation thereof - Google Patents

Abstract

A noble globular carbonaceous powder and a process for preparing the globular carbonaceous powder are provided to have excellent lithium moving characteristics. A heterogeneous carbonaceous material-containing globular carbonaceous powder comprises carbonaceous material scale piece flakes distributed longitudinally and laterally to form a powder globule in such a structure that a carbonaceous material and a heterogeneous carbonaceous material coexist between the flakes in the globule. The carbonaceous material is selected from graphite, hard carbon, and soft carbon. The heterogeneous carbonaceous material-containing globular carbonaceous powder comprises 1 to 90 wt.% of the heterogeneous carbonaceous material. The heterogeneous carbonaceous material-containing globular carbonaceous powder further comprises a surface covering layer formed of at least one material of a petroleum-based pitch, a mortar-based pitch, and a thermoplastic resin.

Description

Globular carbon powder with heterogeneous carbon material coexisting therein and its manufacturing method {HETEROGENEOUS-CARBONACEOUS MATERIALS-INSERTED GLOBULE CARBONACEOUS POWDERS AND PROCESS FOR PREPARATION THEREOF}

1 is a schematic diagram showing the process of pelletizing a single carbon material by rotary pressure,

FIG. 2 is a SEM photograph showing that the scaly globule-shaped spherical carbon material and the heterogeneous carbon material by soft carbon coexisted according to Example 1,

3 is a SEM photograph showing a soft carbon according to Comparative Example 1;

4 is a SEM photograph showing a carbon powder obtained by compacting a single carbon material by the process of FIG. 1 as in Comparative Example 3.

The present invention relates to a spherical carbon powder having a heterogeneous carbon material coexisting therein and having improved properties, and a method of manufacturing the same.

Recently, mobile phones, laptops, digital cameras, and the like have been rapidly spread, and as the usage thereof increases, there is a demand for improving the performance of energy density and power density for secondary batteries, which are driving powers of these devices. In addition, as environmental problems become more severe, legal restrictions are being placed on the production of products such as automobiles using fossil fuel as driving energy. Accordingly, hybrid electric vehicles and electric vehicles are being developed, and development and performance improvement of secondary batteries, which are driving energy of these products, are required.

As secondary batteries used in these products, lithium secondary batteries have been used a lot, and improvements of negative and positive electrode active materials have been continuously studied to improve energy density and power density of these lithium secondary batteries. Materials generally used as the negative electrode active material here are carbon-based graphite and coke, which can be inserted and detached.

Graphite has a theoretical capacity of 372 mAh / g. Natural graphite closest to the theoretical capacity has a relatively high charge / discharge capacity, but has low efficiency and high rate charge / discharge and long life characteristics due to its high reactivity with electrolyte. There is a drawback to not doing it. In addition, in the case of soft carbon such as coke, the charge and discharge capacity is low, but there is an advantage in high rate characteristics and long life characteristics.

It is an object of the present invention to provide a novel globule carbon powder having excellent lithium transfer properties and a method for producing the same.

In order to achieve the above object, in the present invention, the carbon material scale pieces of flakes are distributed longitudinally and horizontally to form one powder globule, and the carbon material and the other heterogeneous carbon material coexist between the flakes in the globules. It provides a different carbon material-containing globule carbon powder having a.

In another aspect, the present invention provides a method for producing heterogeneous carbon powder-containing globule carbon powder comprising the step of mixing the carbon material flakes with the heterogeneous carbon material in the powder state and then rotating pressure.

Hereinafter, the present invention will be described in detail.

As used herein, "carbon material" refers to carbon materials such as graphite, hard carbon, soft carbon, and the like.

The heterogeneous carbonaceous material-containing globule carbon powder of the present invention is used to form the globules between the flakes in the globules while forming one powder globule by dispersing the carbonaceous material scale pieces with average particle diameters of 1 μm to 10 mm. It is characterized in that it has a structure in which the carbon material component and the carbon material of other components coexist.

If the particle size of the carbon material used to form the globules is less than 1 μm in average particle diameter, the particles are too small to prevent the particles from flying and forming globules during rotational pressurization in the globule forming machine. It is not suitable because large particles can be formed.

Forming the carbonaceous scaly flakes into globules is performed through a process such as rotary pressing, wherein the carbonaceous flakes are granulated by a rotary pressing process as shown in FIG. 1 to form globules. The heterogeneous carbon material introduced together with the carbon material flakes forms a shape coexisting inside the globules composed of these scale pieces.

The heterogeneous carbon materials coexisting in the carbon powder globules are graphite, soft carbon, hard carbon, and the like, and are selected from those different from the carbon materials used for forming the basic globules. At this time, the heterogeneous carbon material may be used in an amount of 1 to 90% by weight in the total globule powder.

The particle size of the carbonaceous scaly flakes to be used is, on average, 1 µm to 10 mm, preferably 10 µm to 5000 µm, and more preferably 20 µm to 1000 µm.

In addition, the average particle size before the introduction of the globule former of the heterogeneous carbon material coexisting in the carbon powder globules consisting of the flake pieces of the carbon material scales is 0.01 μm to 1000 μm, preferably 0.1 μm to 100 μm, and more preferably. Preferably it is 1 micrometer-50 micrometers. When the average particle size of the heterogeneous carbonaceous material is less than 0.01 μm before the injection, the particles are too small and have a low density so that they do not coexist in the globules, and when the average particle size is 1000 μm or more, the particles do not coexist in the globules. Even if the particle size is too large, it cannot be used as a battery material.

Rotating pressure for producing the globules in the process can be carried out under a shear stress of 1 to 1,000Kg / cm ² and a tangential speed of 300 to 20,000mm / sec. When the rotational pressure and the shear stress are respectively lower than the lower limit, the globules are not formed at all, and when the upper pressure is higher than the upper limit, the powder is pulverized rather than the globules are formed.

Since the carbon powder containing heterogeneous carbon material according to the present invention obtained by such a process is a globule composed of different carbon materials, the characteristics of each material are combined to compensate for the disadvantages of each other and the characteristics of the advantages. Can be expressed.

The coating process may be further performed by a conventional method known on the surface of the spherical carbon powder. In the coating step, the spherical carbon powder is mixed with a coating material such as petroleum pitch, coal tar pitch, or thermoplastic resin, and pressure is rotated, and then carbonized by heating at 100 to 3,000 ° C., preferably 1,200 to 3,000 ° C. to remove impurities, Surface improvement and graphitization processes.

Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited to the following examples.

Example 1 Preparation of Globule Carbon Powder in which Soft Carbon Coexists in Flaky Graphite

100 g of flaky graphite having an average particle diameter of 100 μm and 100 g of soft carbon having an average particle diameter of 25 μm were placed in a globule forming machine and rotated for 10 minutes under conditions of a shear stress of 300 Kg / cm ² and a tangential velocity of 1000 mm / sec. Different carbon material-containing globule carbon powder was prepared.

The electron scanning microscope (SEM) photograph of the heterogeneous carbon material containing globule carbon powder obtained above is shown in FIG. In the case of flaky graphite, the plate-like graphite is dried roundly during rotational pressurization, and the mixed soft carbon is coexisted between the flaky graphite, and the globule powder is pressed together with the graphite and soft carbon. Therefore, it can be seen that the two represent a mixed particle diameter, and the particle diameter is widely distributed about 0.01 to 1000 μm. The average particle diameter was 1-100 micrometers.

Example 2 Preparation of Globule Carbon Powder in which Soft Carbon Coexists in Flaky Graphite

It was prepared under the same conditions as in Example 1 except that 100 g of flaky graphite and 100 g of soft carbon having an average particle diameter of 25 µm were ground to have an average particle diameter of 30 µm.

Example 3 Preparation of Globule Carbon Powder in which Hard Carbon Coexists in Flaky Graphite

It was prepared under the same conditions as in Example 1 except that 100 g of flaky graphite having an average particle diameter of 100 μm and 100 g of hard carbon having an average particle diameter of 10 μm were used.

Comparative Example 1 Soft Carbon

Soft carbon having an average particle diameter of 25 µm used in Example 1. SEM image thereof is shown in FIG. 3.

(Comparative Example 2) Hard Carbon

A hard carbon having an average particle diameter of 10 µm used in Example 3.

Comparative Example 3 Flaky Graphite Globule Powder

A flaky graphite having an average particle diameter of 100 μm used in Example 1 was put into a globule forming machine, and was spun in the same manner as in Example 1 to prepare spherical flaky graphite having an average particle diameter of 20 μm. The SEM photograph of the is shown in FIG.

(Test example)

The carbon materials of Examples 1 to 3 and Comparative Examples 1 to 3 were heat-treated at 1,000 ° C. for 2 hours to evaluate the performance as a negative electrode active material for lithium secondary batteries, and a sieve having an eye size of 45 μm. Battery characteristics were evaluated by classifying and removing large particles so that the average particle diameter was 1 to 50 µm.

Specifically, the slurry is prepared by mixing the binder (SBR, Styrene Butadien Rubber) and the thickener (CMC, Carboxymethyl Cellulose) to the material prepared in the above example so that the weight ratio of carbon material: binder: thickener is 96: 2: 2. It was. The slurry was coated on a copper current collector, dried, and rolled to prepare a negative electrode plate. The negative electrode, the separator, the electrolyte, and the lithium electrode were laminated in this order to manufacture a half cell for a lithium secondary battery. At this time, the lithium metal and the separator used as the reference electrode were used without special purification of the product, and the electrolyte solution contained ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl containing 1 mol lithium hexafluoride (LiPF ₆ ). A solution of Cheil Industries (DEC) in a 2: 3: 1 volume ratio was used.

Charge and discharge test conditions of the half-cell produced as described above were as follows. Assuming that 300 mA per 1g weight is 1C, the charging condition was controlled at a constant current from 0.01V to 0.01V and a constant voltage from 0.01V to 0.01C at 0.2C, and the discharge condition was controlled at a constant current to 1.5V at 0.2C. In addition, to measure the high rate characteristics, it was discharged at a constant current to 1.5V at 5C.

The results are shown in Table 1 below.

As can be seen in Table 1, the heterogeneous carbon material-containing globule carbon powder according to the present invention can be seen that the high rate and efficiency characteristics at the same time excellent effect while complementing the disadvantages of each carbon material.

The globule carbon powder according to the production method of the present invention can produce a negative active material for a lithium secondary battery having both high efficiency and improved high rate characteristics.

Claims (10)

A carbonaceous material-scale globule carbon powder having a structure in which flake slices are vertically and horizontally distributed to form one powder globule, and the carbon material and other heterogeneous carbon materials coexist between the flakes in the globules. The method of claim 1, Carbon material is a heterogeneous carbon material-containing globular carbon powder, characterized in that selected from graphite, hard carbon and soft carbon. The method of claim 1, A heterogeneous carbon material-containing globular carbon powder, characterized in that the heterogeneous carbon material is included in an amount ranging from 1 to 90% by weight. The method of claim 1, A heterogeneous carbon material-containing globular carbon powder, further comprising a surface coating layer made of at least one of petroleum pitch, coal tar pitch, and thermoplastic resin. Mixing the carbon material flakes and the carbon material with other heterogeneous carbon materials and placing them in a globule forming machine, and rotating and pressing at a shear stress of 1 to 1000 Kg / cm ² and a tangential velocity of 300 to 20000 mm / sec. A method for producing the hetero carbon material-containing globule carbon powder according to any one of claims 1 to 4. The method of claim 5, A method for producing heterogeneous carbon material-containing globular carbon powder, wherein the carbon material flakes have an average particle diameter of 1 μm to 10 mm. The method of claim 5, A method for producing heterogeneous carbon material-containing globular carbon powder, characterized in that the heterogeneous carbon material has an average particle diameter of 0.01 to 1000 µm. The method of claim 5, A method for producing a heterogeneous carbon material-containing globular carbon powder, wherein the carbon material flakes are graphite and the different carbon materials are hard carbon or soft carbon. The method of claim 5, Further comprising a step of surface coating the resulting globule carbon powder with at least one of petroleum pitch, coal tar pitch and thermoplastic resin, followed by heating and carbonizing at 100 to 3,000 ° C. Method for producing carbon powder. A lithium secondary battery comprising the heterogeneous carbon material-containing globular carbon powder according to any one of claims 1 to 4 as a negative electrode active material.

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