KR20220012013A - Method of manufacturing pitch for secondary battery anode material, and anode material manufactured from the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a pitch for a secondary battery negative electrode material, including the steps of: mixing a petrochemical by-product and a boron compound; firstly heat-treating the mixed petrochemical by-product and the boron compound at 150 deg. C to less than 350 deg. C; and forming pitch by secondly heat-treating the mixed petrochemical by-product and the boron compound at 350 deg. C to 500 deg. C.

Description

Method of manufacturing pitch for secondary battery anode material, and anode material manufactured from the same}

The present invention relates to a method for manufacturing a pitch for a secondary battery negative electrode material and to a secondary battery negative electrode material manufactured therefrom.

As governments in each country strengthen environmental regulations, it is expected that the battery market will grow along with the electric vehicle (EV) industry in the automobile sector. The battery is a key component that accounts for 30-40% of the cost of electric vehicles, and cost reduction, high energy and good stability are important. In particular, lithium secondary batteries, which were commercialized in the early 1990s, are widely used among various types of batteries and are very important. .

Lithium secondary batteries have excellent characteristics that can satisfy various conditions required for batteries of electronic devices by not only having high operating voltage and energy density compared to other secondary batteries, but also being able to use them for a long time. Efforts are being made to further develop and expand its application fields to transportation devices, power storage devices, medical devices, and defense devices.

Graphite used as a negative electrode material for lithium secondary batteries is largely divided into natural graphite and artificial graphite. Natural graphite is currently manufactured by methods such as flotation, acid treatment, and spheronization, and by this manufacturing method, defects or corners on the surface are exposed to the surface, so it is directly used as a high-performance and high-efficiency anode material for lithium secondary batteries. has limitations.

On the other hand, artificial graphite can be produced by graphitizing pitch, which is a coke precursor, but heat treatment for graphitization requires a high temperature of 3000 ° C. or higher, so the price is expensive and localization is difficult because of the technical limitations of the high temperature process. Methods to do this have been studied.

In this regard, Republic of Korea Patent No. 10-1597208 discloses a method for producing a pitch for an anode material using a boron compound, and a method for producing a pitch prepared by reacting a boron compound and a pitch in a closed system and an open system has been disclosed. A method of manufacturing a carbon negative electrode material by carbonizing pitch has been disclosed.

However, the carbon anode material of the above literature is soft carbon, which is a low-temperature heat-treated carbon, and the soft carbon is relatively inexpensive and has excellent output characteristics by manufacturing a pitch intermediate using petroleum and coal-based organic materials as raw materials and performing low-temperature carbonization at around 1000 ° C. has advantages, but has a disadvantage in that the capacity is relatively low compared to graphite anode materials and the yield is low during pitch manufacturing.

On the other hand, when graphitizing the pitch, it is known that boron can be used as a catalyst to lower the graphitization temperature of the pitch. There are problems such as lowering

Accordingly, the present inventors prepare pitch by reacting a boron compound and a petrochemical by-product in order to solve the above problem, but by controlling the reaction conditions, the graphitization degree of the pitch is increased and the generation of boron carbide is suppressed and used as an anode material A method for producing an excellent pitch and a method for producing graphite doped with boron were developed and completed the present invention.

Republic of Korea Patent No. 10-1597208

The object of the present invention is

An object of the present invention is to provide a method for manufacturing a pitch for a secondary battery negative electrode material and a secondary battery negative electrode material manufactured therefrom.

In order to achieve the above object,

In one aspect,

mixing a petrochemical by-product and a boron compound;

Primary heat treatment of the mixed petrochemical by-products and boron compound at 150°C to less than 350°C; and

Secondary heat treatment of the mixed petrochemical by-product and boron compound at 350°C to 500°C to form a pitch;

In this case, the first heat treatment may be performed at 150° C. to less than 350° C. for 30 minutes to 180 minutes, and the second heat treatment may be performed at 350° C. to 500° C. for 60 minutes to 300 minutes.

In addition, the first heat treatment may be preferably performed at 180° C. to 300° C. for 30 minutes to 120 minutes.

In addition, the mixing may be performed by adding and mixing the petrochemical by-product to the solution in which the boron compound is dispersed.

In addition, in the mixing, petrochemical by-products and boron compounds may be mixed in a weight ratio of 100: 1 to 100: 10, preferably 100: 3 to 100: 5 by weight.

The petrochemical by-product is 1 selected from the group consisting of pyrolysis fuel oil, heavy oil, extract heavyoil, vacuum residue, atmospheric residue and oil sand bitumen may be more than one species.

The boron compound may be at least one compound selected from the group consisting of H ₃ BO ₃ , B ₂ O ₃ and Na ₂ B ₄ O ₇ .

Also, in another aspect,

A pitch for a secondary battery negative electrode material manufactured by the above manufacturing method and containing boron is provided.

Also, in another aspect,

producing a pitch by the above method; and

There is provided a method for manufacturing a secondary battery negative electrode material comprising a graphite doped with boron;

In this case, the heat treatment step is

third heat treatment of the pitch at 700° C. to 1100° C.; and

The tertiary heat treatment of the pitch at 2400 °C to 2800 °C quaternary heat treatment; may include.

In another aspect

There is provided a secondary battery negative electrode material manufactured by the above manufacturing method and comprising boron-doped graphite.

The negative electrode material may include boron carbide (B ₄ C) in an amount of 1 wt% or less.

The method for producing a pitch for a secondary battery negative electrode material according to an embodiment is prepared by reacting a boron compound and a petrochemical by-product at a low temperature, and using the pitch, graphite with a high graphitization degree at a low temperature of 3000 ° C. or less. can

The method for manufacturing a secondary battery negative electrode material including boron-doped graphite according to an embodiment is a method of manufacturing a negative electrode material containing boron-doped graphite using the pitch, and by including boron, graphite having a high degree of crystallinity is It is possible to improve the low speed characteristic, which is a disadvantage of the present invention.

In addition, the production method can suppress the generation of boron carbide (B ₄ C), and it is possible to solve the problem caused by the inclusion of boron carbide (B ₄ C) in the negative electrode material, for example, the problem of lowering the capacity characteristics of the battery. have.

1 is a flowchart showing a method of manufacturing a pitch for a secondary battery negative electrode material according to an embodiment;
2 is a flowchart illustrating a method of manufacturing a secondary battery negative electrode material including boron-doped graphite according to an embodiment;
3 is a graph showing the results of X-ray diffraction analysis (XRD) of a secondary battery negative electrode material containing boron-doped graphite prepared according to Examples and Comparative Examples;
4 is a graph showing an enlarged part of the XRD graph of FIG. 3,
5 is an electrochemical characteristic evaluation graph of a secondary battery negative electrode material including boron-doped graphite prepared according to Examples and Comparative Examples.

Hereinafter, the present invention will be described using examples and drawings. However, the following embodiments may be modified in various other examples, and the scope of the present invention is not limited to the embodiments described below. In addition, the following examples are provided in order to more completely explain the present invention to those with average knowledge in the art. In addition, "including" a certain component throughout the specification means that other components may be further included, rather than excluding other components, unless otherwise stated.

In one aspect,

mixing a petrochemical by-product and a boron compound;

Primary heat treatment of the mixed petrochemical by-products and boron compound at 150°C to less than 350°C; and

Secondary heat treatment of the mixed petrochemical by-product and boron compound at 350°C to 500°C to form a pitch;

Hereinafter, a method of manufacturing a pitch for a secondary battery negative electrode material provided in one aspect will be described in detail for each step with reference to the drawings.

1 is a flowchart illustrating a method of manufacturing a pitch for a secondary battery negative electrode material according to an embodiment.

The method of manufacturing a pitch for a secondary battery negative electrode material according to an embodiment includes mixing a petrochemical by-product and a boron compound.

In this case, the petrochemical by-product means a by-product generated in the process of producing a petrochemical product.

Specifically, by-products generated in the terephthalic acid manufacturing process, phthalic acid manufacturing process, isophthalic acid manufacturing process, 2,6-naphthalene dicarboxylic acid manufacturing process, trimelic acid manufacturing process, methmethylacrylic acid manufacturing process, or nitro toluene manufacturing process means

The petrochemical by-products include, but are not limited to, a compound having a carbonyl group (C=O), a compound having a sulfate group (-SOx) by sulfation, or a compound having a nitrate group (-NOx) by nitration. More specifically, the petrochemical by-products include benzoic acid, para-toluic acid, styrone oxide, 1,2-epoxy-phenoxypropane, glycidyl-2-methylphenyl ether, (2,3-epoxypropyl)benzene, 1- Phenylpropylene oxide, stilbene oxide, 2- (or 3- or 4-) halo (eg chloro, fluorine, bromo, or iodo) stilbene oxide, benzyl glycidyl ether, C1-10 straight chain or branched chain alkyl (e.g. methyl, ethyl, propyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, etc.) phenyl glycidyl ether, 4-halo (e.g. chloro, fluoro Furnace, bromo, or iodo) phenyl glycidyl ether, etc. may be present, but preferably Pyrolysis Fuel Oil (PFO), heavy crude, extract heavy crude, decompression residue It may be at least one selected from the group consisting of vacuum residue (VR), atmospheric residue, and oil sand bitumen.

In addition, the boron compound may be one or more compounds selected from the group consisting of H ₃ BO ₃ , B ₂ O ₃ and Na ₂ B ₄ O ₇ for the reaction with the petrochemical by-product, but preferably the petroleum H ₃ BO ₃ having excellent reaction activity with the chemical by-product may be used.

In the above step, the petrochemical by-product and boron compound may be mixed in a weight ratio of 100:1 to 100:10, preferably 100:3 to 100:5 by weight.

If, when mixing the boron compound in an amount of less than 1% by weight compared to the petrochemical by-product, the effect of the addition of the boron compound, that is, the effect of lowering the graphitization temperature of the produced pitch and increasing the graphitization degree, is insufficient. When mixed by adding and mixing the boron compound in an amount exceeding 5% by weight compared to the petrochemical by-product, graphite is produced by graphitizing the produced pitch, and boron carbide is produced together, and battery characteristics when used as an anode material There may be a problem of lowering the

In addition, in order to increase the reactivity of the boron compound and the petrochemical by-product, the mixing in the above step is preferably performed by a method of uniformly mixing the petrochemical by-product and the boron compound. Accordingly, it may be carried out by a method of adding the petrochemical by-product and the boron compound to a solvent, preferably preparing a solution in which a boron compound is dispersed in a solvent, and adding the petrochemical by-product to the solution and mixing it. can be performed.

In this case, the solvent may be at least one selected from the group consisting of water, ethanol and methanol, but is not limited thereto, and various solvents capable of dispersing the petrochemical by-product and boron compound may be used.

In addition, the boric acid compound and the solvent in a solution in which the boron compound is dispersed may be included in a mass ratio of 1:6 to 1:20. This is for uniformly dispersing the boron compound and uniformly reacting with the petrochemical compound thereafter. Since the boron compound is not sufficiently dispersed within, there may be a problem in that the boric acid compound is agglomerated during pitch production, and the boric acid compound is included in less than the mass ratio range of 1:6 to 1:20 compared to the solvent, During the pitch production reaction, the rate at which the solvent is vaporized becomes too high, and the pressure in the reactor rises quickly, which can be dangerous.

In addition, the mixing, which is performed by adding the petrochemical by-product to a solution in which the boron compound is dispersed in a solvent, may be performed using a ball mill, a stirrer, etc., but is not limited thereto, and various methods for dispersing the particles in the solution can be performed.

In addition, during the mixing, an organic solvent, preferably tetrahydrofuran (THF), may be further added to increase dispersibility.

The method of manufacturing a pitch for a secondary battery negative electrode material according to an embodiment includes the step of heat-treating the mixed petrochemical by-product and boron compound at 150° C. to 500° C. to form a pitch.

The step is a step of forming a pitch containing carbon and boron by reacting the petrochemical by-product and the boron compound.

Accordingly, if the heat treatment is performed at less than 150° C., the reaction of the petrochemical by-product and the boron compound is not sufficiently performed, so a problem that the pitch is not manufactured may occur, and the heat treatment is performed at a temperature exceeding 500° C. When performed, a problem in which the yield of the pitch is lowered may occur due to the rapid coking of the pitch.

The heat treatment may be preferably performed at 150° C. to 500° C. for 1 hour to 10 hours, and more preferably in an inert atmosphere.

At this time, in order to ensure that boron is uniformly dispersed in the produced pitch, the heat treatment is performed in a first heat treatment at a lower temperature at which the reaction is initiated, and then the second heat treatment is performed at a higher temperature at which the reaction is completed, step by step It may be preferable to carry out a heat treatment method.

Accordingly, the step is a step of primary heat treatment of the mixed petrochemical by-product and boron compound at 150 ℃ to less than 350 ℃; and forming a pitch by performing secondary heat treatment of the mixed petrochemical by-product and boron compound at 350°C to 500°C.

In this case, the first heat treatment may be performed at 150° C. to less than 350° C. for 30 minutes to 180 minutes, and the second heat treatment may be performed at 350° C. to 500° C. for 60 minutes to 300 minutes.

In addition, it may be more preferable to perform the first heat treatment at 180° C. to 300° C. for 30 minutes to 120 minutes.

The primary heat treatment is to ensure that the boron compound is uniformly distributed in the pitch produced by the reaction of the petrochemical by-product and the boron compound, and if the primary heat treatment is not performed, the graphitization degree of the produced pitch is It may be low, and in the process of graphitizing the produced pitch, the boron is not doped in the crystal of the graphite and there may be a problem of generating a separate compound, boron carbide (B ₄ C), the boron carbide (B ₄ C) is an insulating material, and when included in the negative electrode material, may cause a problem of reducing the capacity characteristics and speed characteristics of the battery.

The method for producing a pitch for a secondary battery negative electrode material provided in one aspect can prepare a pitch in which boron is uniformly dispersed in the pitch by controlling the reaction rate of a petrochemical by-product and a boron compound as described above.

Since the prepared pitch is contained in graphite crystals without generating boron carbide (B ₄ C) in the graphitization process by uniformly dispersed boron, the speed characteristics of the battery when graphitizing the prepared pitch and using it as an anode material At the same time, it is possible to improve the specific capacity characteristics.

In another aspect,

It is manufactured by the above manufacturing method and provides a pitch for a secondary battery negative electrode material containing boron.

The pitch includes uniformly dispersed boron, and since the boron is contained in graphite crystals without generating boron carbide (B ₄ C) during the graphitization process, the pitch is graphitized and used as a secondary battery negative electrode material. It is possible to improve the specific capacity characteristics while improving the speed characteristics.

In another aspect,

producing a pitch by the above method; and

There is provided a method for manufacturing a secondary battery negative electrode material comprising a graphite doped with boron;

2 is a flowchart illustrating a method of manufacturing a secondary battery negative electrode material including graphite doped with boron according to an embodiment.

The method for manufacturing a secondary battery negative electrode material including boron-doped graphite according to an embodiment includes manufacturing a pitch by the above-described method.

That is, the step comprises mixing the petrochemical by-product and the boron compound and forming a pitch by heat-treating the mixed petrochemical by-product and the boron compound at 150° C. to 500° C.

In this case, the petrochemical by-product means a by-product generated in the process of producing a petrochemical product.

Specifically, by-products generated in the terephthalic acid manufacturing process, phthalic acid manufacturing process, isophthalic acid manufacturing process, 2,6-naphthalene dicarboxylic acid manufacturing process, trimelic acid manufacturing process, methmethylacrylic acid manufacturing process, or nitro toluene manufacturing process means

The petrochemical by-products include, but are not limited to, a compound having a carbonyl group (C=O), a compound having a sulfate group (-SOx) by sulfation, or a compound having a nitrate group (-NOx) by nitration. More specifically, the petrochemical by-products include benzoic acid, para-toluic acid, styrone oxide, 1,2-epoxy-phenoxypropane, glycidyl-2-methylphenyl ether, (2,3-epoxypropyl)benzene, 1- Phenylpropylene oxide, stilbene oxide, 2- (or 3- or 4-) halo (eg chloro, fluorine, bromo, or iodo) stilbene oxide, benzyl glycidyl ether, C1-10 straight chain or branched chain alkyl (e.g. methyl, ethyl, propyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, etc.) phenyl glycidyl ether, 4-halo (e.g. chloro, fluoro Furnace, bromo, or iodo) phenyl glycidyl ether, etc. may be present, but preferably Pyrolysis Fuel Oil (PFO), heavy crude, extract heavy crude, decompression residue It may be at least one selected from the group consisting of vacuum residue (VR), atmospheric residue, and oil sand bitumen.

In addition, the boron compound may be one or more compounds selected from the group consisting of H ₃ BO ₃ , B ₂ O ₃ and Na ₂ B ₄ O ₇ for the reaction with the petrochemical by-product, but preferably the petroleum H ₃ BO ₃ having excellent reaction activity with the chemical by-product may be used.

In the step of mixing the petrochemical by-product and the boron compound, the petrochemical by-product and the boron compound may be mixed in a weight ratio of 100: 1 to 100: 10, preferably in a weight ratio of 100: 3 to 100: 5. can do.

If, when mixing the boron compound in an amount of less than 1% by weight compared to the petrochemical by-product, the effect of the addition of the boron compound, that is, the effect of lowering the graphitization temperature of the produced pitch and increasing the graphitization degree, is insufficient. When mixed by adding and mixing an amount exceeding 10% by weight of the boron compound compared to the petrochemical by-product, graphite is produced by graphitizing the produced pitch, and boron carbide is produced together, and battery characteristics when used as an anode material There may be a problem of lowering the

In order to increase the reactivity of the boron compound and the petrochemical by-product, the mixing is preferably performed by uniformly mixing the petrochemical by-product and the boron compound.

Accordingly, it may be carried out by a method of adding the petrochemical by-product and the boron compound to a solvent, preferably preparing a solution in which a boron compound is dispersed in a solvent, and adding the petrochemical by-product to the solution and mixing it. can be performed.

In this case, the solvent may be at least one selected from the group consisting of water, ethanol and methanol, but is not limited thereto, and various solvents capable of dispersing the petrochemical by-product and boron compound may be used.

In addition, the boric acid compound and the solvent in a solution in which the boron compound is dispersed may be included in a mass ratio of 1:6 to 1:20. This is for uniformly dispersing the boron compound and uniformly reacting with the petrochemical compound thereafter. Since the boron compound is not sufficiently dispersed within, there may be a problem in that the boric acid compound is agglomerated during pitch production, and the boric acid compound is included in less than the mass ratio range of 1:6 to 1:20 compared to the solvent, During the pitch production reaction, the rate at which the solvent is vaporized becomes too high, and the pressure in the reactor rises quickly, which can be dangerous.

In addition, the mixing, which is performed by adding the petrochemical by-product to a solution in which the boron compound is dispersed in a solvent, may be performed using a ball mill, a stirrer, etc., but is not limited thereto, and various methods for dispersing the particles in the solution can be performed.

In addition, during the mixing, an organic solvent, preferably tetrahydrofuran (THF), may be further added to increase dispersibility.

In addition, the step of forming a pitch by heat-treating the mixed petrochemical by-product and boron compound at 150° C. to 500° C. is a step of forming a pitch containing carbon and boron by reacting the petrochemical by-product and boron compound.

Accordingly, if the heat treatment is performed at less than 150° C., the reaction of the petrochemical by-product and the boron compound is not sufficiently performed, so a problem that the pitch is not manufactured may occur, and the heat treatment is performed at a temperature exceeding 500° C. When performed, a problem in which the yield of the pitch is lowered may occur due to the rapid coking of the pitch.

The heat treatment may be preferably performed at 150° C. to 500° C. for 1 hour to 10 hours, and more preferably in an inert atmosphere.

At this time, in order to ensure that boron is uniformly dispersed in the produced pitch, the heat treatment is performed in a first heat treatment at a lower temperature at which the reaction is initiated, and then the second heat treatment is performed at a higher temperature at which the reaction is completed, step by step It may be preferable to carry out a heat treatment method.

Accordingly, the step is a step of primary heat treatment of the mixed petrochemical by-product and boron compound at 150 ℃ to less than 350 ℃; and forming a pitch by performing secondary heat treatment of the mixed petrochemical by-product and boron compound at 350°C to 500°C.

In this case, the first heat treatment may be performed at 150° C. to less than 350° C. for 30 minutes to 180 minutes, and the second heat treatment may be performed at 350° C. to 500° C. for 60 minutes to 300 minutes.

It may be more preferable to perform the first heat treatment at 180° C. to 300° C. for 30 minutes to 120 minutes.

The primary heat treatment is to ensure that the boron compound is uniformly distributed in the pitch produced by the reaction of the petrochemical by-product and the boron compound, and if the primary heat treatment is not performed, the graphitization degree of the produced pitch is It may be low, and in the process of graphitizing the produced pitch, the boron is not doped in the crystal of the graphite and there may be a problem of generating a separate compound, boron carbide (B ₄ C), the boron carbide (B ₄ C) is an insulating material, and when included in the negative electrode material, may cause a problem of reducing the capacity characteristics and speed characteristics of the battery.

A method of manufacturing a secondary battery negative electrode material including boron-doped graphite provided in one aspect includes heat-treating the pitch at a temperature of 700°C to 2800°C.

The heat treatment is for producing graphite by heat-treating the pitch at a high temperature, and may be preferably performed in an inert atmosphere.

In addition, the step of heat treatment is preferably a third heat treatment step of the pitch at 700 ℃ to 1100 ℃; and heat-treating the tertiary heat-treated pitch at 2400°C to 2800°C.

The third heat treatment is to remove the volatile material in the pitch for carbonization, and may preferably be performed at 700° C. to 1100° C. for 30 minutes to 3 hours.

If the secondary heat treatment is performed at less than 700°C or for a time of less than 30 minutes, the volatile material is not sufficiently discharged, so graphitization may not be performed properly in the high-temperature process thereafter, exceeding 1200°C If it is carried out at a temperature of a certain temperature or for a time exceeding 3 hours, too much energy is consumed and a problem of increasing the process cost may occur.

The step of graphitizing the tertiary heat-treated pitch at 2400 ° C. to 2800 ° C. is to prepare graphite having crystallinity from the carbonized pitch, preferably at 2400 ° C. to 2800 ° C. for 30 minutes to 1 hour. can

If the fourth heat treatment is performed at less than 2400° C., graphitization may not occur, and if it is performed for less than 30 minutes, a low yield of the produced boron-doped graphite may occur. have.

In addition, when the fourth heat treatment step is performed at a temperature exceeding 2800° C. or for a time exceeding 1 hour, too much energy is consumed and a problem of increasing the process cost may occur.

The method of manufacturing a secondary battery negative electrode material including boron-doped graphite according to an embodiment is a method of manufacturing a negative electrode material by graphitizing a pitch containing uniformly dispersed boron, and the boron dispersed in the pitch is boron carbide (B ₄ ). C) can be made to be doped in the graphite crystal without being produced as a separate compound, so that the negative electrode material prepared by the above method may contain boron carbide (B ₄ C) in an amount of 1 wt% or less.

Accordingly, the negative electrode material prepared by the above manufacturing method is doped with boron in the graphite crystal, so that it has excellent speed characteristics of the secondary battery, is inert to lithium ions, and contains a trace amount of boron carbide (B ₄ C) having insulation in 1 wt% or less. By having or not including it, there is an advantage in that the specific capacity of the battery is high.

In another aspect,

A secondary battery negative electrode material is provided, which is manufactured by the above manufacturing method and includes graphite doped with boron.

The negative electrode material is doped with boron in the graphite crystal, so that the speed characteristics of the secondary battery are excellent, and boron carbide (B ₄ C) which is inert to lithium ions and has insulation is included in a trace amount of 1 wt% or less or not, It has the advantage of high specific capacity of the battery.

Hereinafter, the present invention will be described in detail through Examples and Experimental Examples.

However, the following examples and experimental examples are only to illustrate the present invention, the content of the present invention is not limited by the following examples.

<Example 1>

Step 1: A solution of 25 g of boric acid (H ₃ BO ₃ ) dispersed in 150 ml of ethanol was stirred at 60° C. for 1 hour to prepare a boric acid solution.

Step 2: The boric acid solution was put into the reactor, and 500 g of PFO, a petroleum residue, was added, followed by stirring at a speed of 50 rpm for 30 minutes. In the reactor, nitrogen gas was flowed to form an inert atmosphere inside the reactor.

Step 3: A pitch was prepared by adjusting the temperature inside the reactor to 180° C. for 30 minutes, 250° C. for 30 minutes, 300° C. for 30 minutes, and 420° C. for 3 hours.

Step 4: After putting the prepared pitch into a carbonization furnace through which nitrogen gas flows, heat treatment at 1200° C. for 1 hour, and then cooling to room temperature to prepare a boric acid-doped carbon material.

Step 5: The prepared boric acid-doped carbon material was heat-treated at 2500° C. for 1 hour to graphitize, and then the particle size was adjusted to 10 to 25 μm to prepare an anode material for a secondary battery including boron-doped graphite.

<Comparative Example 1>

A negative electrode material for a secondary battery was manufactured in the same manner as in Example 1, except that in Example 1, no boric acid solution was added to the reactor.

<Comparative Example 2>

In Example 1, a negative electrode material for a secondary battery comprising boron-doped graphite was prepared in the same manner as in Example 1, except that the temperature inside the reactor was changed at 420° C. for 3 hours in step 3 .

<Experimental Example 1>

X-ray diffraction analysis using X-ray diffraction (Rigaku D/Max 2200 V, Bruker: CuK α radiation) to analyze the components of the negative electrode material prepared in Example 1, Comparative Example 1 and Comparative Example 2 ( XRD) was performed, and the results are shown in FIGS. 2 and 3 .

As shown in FIG. 2 , it can be seen that the negative electrode materials prepared by the manufacturing methods of Example 1, Comparative Example 1, and Comparative Example 2 all include graphite.

In addition, as shown in FIG. 3 , boron carbide (B ₄ C) was contained in the negative electrode material prepared by Comparative Example 2 among Examples 1 and 2 prepared using boric acid, whereas in Example 1 It can be seen that boron carbide (B ₄ C) is not included in the anode material manufactured by

This is in the case of Comparative Example 2, in which the pitch is formed by heat treatment at a temperature of 350 ° C. to 500 ° C., the boron in the pitch cannot be uniformly dispersed, while boron carbide (B ₄ C) is produced in the graphitization process, while 180 ° C. to 350 ° C. In the case of Example 1 in which the pitch is generated by performing the primary heat treatment at a temperature of less than ℃ and then performing the secondary heat treatment at a temperature of 350 to 500℃, boron in the pitch can be uniformly dispersed, so that the graphitization process In , it can be seen that boron is uniformly doped in the graphite crystal, so that boron carbide (B ₄ C) is not generated.

<Experimental Example 2>

For the negative electrode materials prepared in Example 1, Comparative Example 1, and Comparative Example 2, the graphitization degree was measured by the following method, and the results are shown in Table 1 below.

At this time, the graphitization degree was calculated by the following formula.

P(Graphitization degree, %)=(3.44-d(002)/(0.086)*100

(In this case, d(002) is the interplanar distance calculated through the graphtite(002) peak of the XRD graph of FIG. 2)

Example 1 Comparative Example 1 Comparative Example 2 d(002) 3.358 Å 3.374 Å 3.362 Å Graphitization degree (%) 94.5 76.5 91.1

As shown in Table 1, it can be seen that the graphitization degree of Example 1 and Comparative Example 2 using boric acid compared to Comparative Example 1 not using boric acid was significantly higher.

In addition, as a result of comparison of Example 1 and Comparative Example 2, after performing the primary heat treatment at a temperature of 180 ° C. to less than 350 ° C. compared to the case of manufacturing the pitch by performing a single heat treatment, the second at a temperature of 350 ° C. to 500 ° C. When the pitch is manufactured by a method of performing heat treatment, it can be seen that the graphitization degree (%) is higher.

<Experimental Example 3>

In order to confirm the electrochemical properties of the negative electrode materials prepared in Example 1, Comparative Example 1 and Comparative Example 2, a half-cell was constructed in the following manner, and then, in order to evaluate the electrochemical properties of the half-cell, Battery Cycler (WBCS 3000, Won A Tech) was used to test charge-discharge and speed characteristics. At this time, the charging/discharging test was conducted in CC-CV mode, the cut-off voltage was 0.01 ~ 1.5 V, and the rate characteristic changed the discharge current to 0.1 C, 0.5 C, 1 C, 2 C, 0.1 C, and various C The test was performed at -rate, and the results are shown in FIG. 5 .

(Half-cell manufacturing)

A coin-type half-cell was manufactured using a lithium foil as a counter electrode.

The prepared negative electrode material was used as the active material of the measuring electrode, and CMC (Carboxymethyl Cellulose, MTI Korea) and SBR (Styrene-Butadiene Rubber, MTI Korea) were used as the binder. The active material, SBR and CMC were mixed in a weight ratio of 97:1.5:1.5, and 20 ml of distilled water was added, and then an electrode slurry was prepared by a thinky mixer (ARE-310, Thinky Corporation). The prepared electrode slurry was coated on a copper foil to a thickness of 130 μm and dried at room temperature for 12 hours and at 120° C. for 12 hours. By rolling the completely dried electrode, the electrode density was adjusted to 1.5 ± 0.1 g/cm ³ to complete the preparation of the measuring electrode. At this time, LiPF6 (EC : DEC = 1 : 1 vol.%) was used as the electrolyte to investigate the characteristics of the battery.

As shown in FIG. 5 , in the case of Comparative Example 2, it can be seen that the specific capacity was lower than that of Comparative Example 1 in which boron was not used. This is considered to be because, in the case of Comparative Example 1, boron carbide (B ₄ C), which is an insulator, was generated during the graphitization process.

In addition, it can be seen that the specific capacity of the negative electrode material prepared in Example 1 is superior to those of Comparative Examples 1 and 2. This is, the anode material prepared in Example 1 was prepared by producing pitch using petroleum chemical by-product and boron, but performing multi-step heat treatment under specific conditions to prepare pitch, and graphitizing it, compared to Comparative Examples 1 and 2 It can be seen that this is because the graphitization degree is high and at the same time, it does not contain boron carbide (B ₄ C), which is an insulator.

Claims (12)

mixing a petrochemical by-product and a boron compound;
Primary heat treatment of the mixed petrochemical by-products and boron compound at 150°C to less than 350°C; and
Secondary heat treatment of the mixed petrochemical by-product and boron compound at 350°C to 500°C to form a pitch;
The method of claim 1,
The first heat treatment is performed at 150 ° C. to less than 350 ° C. for 30 minutes to 180 minutes, and the secondary heat treatment is performed at 350 ° C. to 500 ° C. for 60 minutes to 300 minutes, a method for producing a pitch for a secondary battery negative electrode material.
The method of claim 1,
The primary heat treatment is performed at 180 ° C. to 300 ° C. for 30 minutes to 120 minutes, a method for producing a pitch for a secondary battery negative electrode material.
The method of claim 1,
The mixing is performed by adding and mixing the petrochemical by-product to the solution in which the boron compound is dispersed, a method for producing a pitch for a secondary battery negative electrode material.
The method of claim 1,
The mixing is a method for producing a pitch for a secondary battery negative electrode material by mixing a petrochemical by-product and a boron compound in a weight ratio of 100:1 to 100:10.
The method of claim 1,
The petrochemical by-product is 1 selected from the group consisting of pyrolysis fuel oil, heavy oil, extract heavyoil, vacuum residue, atmospheric residue and oil sand bitumen A method of producing a pitch for a secondary battery negative electrode material, which is more than a species.
The method of claim 1,
The boron compound is at least one compound selected from the group consisting of H ₃ BO ₃ , B ₂ O ₃ and Na ₂ B ₄ O ₇ A method for producing a pitch for a secondary battery negative electrode material.
A pitch for a secondary battery negative electrode material manufactured by the manufacturing method of claim 1 and containing boron.
The method of claim 1 comprising the steps of producing a pitch; and
Heating the pitch at a temperature of 700 °C to 2800 °C; Method of manufacturing a secondary battery negative electrode material comprising boron-doped graphite comprising a.
10. The method of claim 9,
The heat treatment step
third heat treatment of the pitch at 700° C. to 1100° C.; and
A method of manufacturing a secondary battery negative electrode material comprising boron-doped graphite comprising a; quaternary heat treatment of the tertiary heat-treated pitch at 2400° C. to 2800° C.
A secondary battery negative electrode material manufactured by the manufacturing method of claim 9 and comprising boron-doped graphite.
12. The method of claim 11,
The negative electrode material is a secondary battery negative electrode material comprising boron carbide (B ₄ C) in an amount of 1 wt% or less.

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