KR102424526B1 - Manufacturing method of negative active material for secondary battery and negative active material for secondary battery therefrom, and Lithium secondary battery comprising the material - Google Patents

Abstract

The present invention comprises the steps of coating natural graphite with a heavy oil-based liquid coating material; And heat-treating to satisfy the following Relation 3; and a method for producing a negative active material for a secondary battery for preparing a negative active material satisfying the following Relations 1 and 2 including; It relates to a lithium secondary battery comprising.
[Relational Expression 1]
0 ≤ I _R1 /I _hcp ≤ 0.2
[Relational Expression 2]
0 ≤ I _R2 /I _hcp ≤ 0.2
[Relational Expression 3]
I _{286 eV} /I _max ≤ 0.1
(In Relations 1 or 2, I _R1 is the intensity of the peak at 2θ = 43.2 to 43.5 °, which is the diffraction angle of the rumbohedral structure on the XRD, and I _R2 is the diffraction angle of the rumbohedral structure on the XRD 2θ = 46 is the intensity of the peak at ~46.2°, I _hcp is the intensity of the peak at 2θ = 42.2~42.5°, which is the diffraction angle due to the hexagonal dense structure (hcp) on XRD, in Relation 3, I _286eV is the It is the intensity of the peak, and I _max is the intensity of the peak appearing at 284 ~ 285 eV on XPS.)

Description

A method of manufacturing a negative active material for a secondary battery, a negative active material for a secondary battery prepared therefrom, and a lithium secondary battery comprising a negative active material for a secondary battery {Manufacturing method of negative active material for secondary battery and negative active material for secondary battery therefrom, and Lithium secondary battery comprising the material}

The present invention relates to a method of manufacturing a negative active material for a secondary battery, and also to a lithium secondary battery comprising a negative active material for a secondary battery prepared therefrom, and a negative active material for a secondary battery.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and among such secondary batteries, lithium secondary batteries having high energy density and voltage are commercialized and widely used.

In particular, lithium secondary batteries for electric vehicles require good long-life characteristics and high-temperature storage characteristics due to the nature of their use. is necessary to suppress

In the case of artificial graphite used as an anode active material, compared to natural graphite, it shows excellent lifespan characteristics and high temperature storage characteristics, but has a problem of high manufacturing cost and low capacity. In the case of natural graphite, the price is low as opposed to artificial graphite And it has a high capacity, but there are problems in that the initial efficiency is low and the chemical stability is poor due to the functional groups contained in natural graphite.

Accordingly, there is a demand for the development of an anode active material having both the advantages of artificial graphite and the advantages of natural graphite.

As a similar prior document for this, Korean Patent Application Laid-Open No. 10-2015-0030705 (2015.03.20) is presented.

Korean Patent Publication No. 10-2015-0030705 (2015.03.20)

An object of the present invention is to provide a method for preparing a negative active material for secondary batteries capable of improving lifespan characteristics and high-temperature storage characteristics by improving structural and chemical stability, a negative electrode active material for secondary batteries prepared therefrom, and lithium containing an anode active material for secondary batteries To provide a secondary battery.

The present invention comprises the steps of coating natural graphite with a heavy oil-based liquid coating material; And heat-treating to satisfy the following Relational Equation 3; including; It relates to a lithium secondary battery.

[Relational Expression 1]

0 ≤ I _R1 /I _hcp ≤ 0.2

[Relational Expression 2]

0 ≤ I _R2 /I _hcp ≤ 0.2

[Relational Expression 3]

I _{286 eV} /I _max ≤ 0.1

In Relations 1 or 2, I _R1 is the intensity of the peak at 2θ = 43.2 to 43.5°, which is a diffraction angle by the rumbohedral structure on XRD, and I _R2 is the diffraction angle 2θ = 46 to 46.2 by the rumbohedral structure on the XRD is the intensity of the peak at °, I _hcp is the intensity of the peak at 2θ = 42.2 ~ 42.5 °, which is the diffraction angle by the hexagonal dense structure (hcp) on the XRD,

In Relation 3, I _{286 eV} is the intensity of the peak appearing at 286 eV on XPS, and I _max is the intensity of the peak appearing at 284 ~ 285 eV on XPS.

The method for manufacturing a negative active material for a secondary battery according to the present invention can prepare an anode active material for a secondary battery with improved chemical and structural stability, thereby obtaining an anode active material with improved lifespan characteristics and high temperature storage characteristics. In addition, an anode active material having a high reversible capacity and initial efficiency can be obtained, and the cost can be reduced by using natural graphite as a raw material.

1 is an anode active material prepared according to Example 1 and XRD (X-ray diffraction) measurement data of Comparative Examples 1 and 2,
2 is an X-ray photoelectron spectroscopy (XPS) measurement data of the negative active material prepared according to Example 1 and Comparative Examples 1 and 2;

Hereinafter, with reference to the accompanying drawings, a method for manufacturing a negative active material for a secondary battery of the present invention, a negative active material for a secondary battery prepared therefrom, and a lithium secondary battery including a negative active material for a secondary battery will be described in detail. At this time, if there is no other definition in the technical terms and scientific terms used, it has the meaning commonly understood by those of ordinary skill in the art to which this invention belongs, and the gist of the present invention in the following description and accompanying drawings Descriptions of known functions and configurations that may be unnecessarily obscure will be omitted.

The present invention relates to a method for manufacturing an anode active material for a secondary battery, comprising the steps of: coating natural graphite with a heavy oil-based liquid coating material; And it relates to a method of manufacturing a negative electrode active material satisfying the following Relations 1 and 2, including;

[Relational Expression 1]

0 ≤ I _R1 /I _hcp ≤ 0.2

[Relational Expression 2]

0 ≤ I _R2 /I _hcp ≤ 0.2

[Relational Expression 3]

I _{286 eV} /I _max ≤ 0.1

In Relations 1 or 2, I _R1 is the intensity of the peak at 2θ = 43.2 to 43.5°, which is a diffraction angle by the rumbohedral structure on XRD, and I _R2 is the diffraction angle 2θ = 46 to 46.2 by the rumbohedral structure on the XRD is the intensity of the peak at °, I _hcp is the intensity of the peak at 2θ = 42.2 ~ 42.5 °, which is the diffraction angle by the hexagonal dense structure (hcp) on the XRD,

In Relation 3, I _{286 eV} is the intensity of the peak appearing at 286 eV on XPS, and I _max is the intensity of the peak appearing at 284 to 285 eV on XPS. It is the peak measured due to

In the case of conventional natural graphite manufactured by using a solid coating material and undergoing heat treatment at around 1100°C, chemical stability is lowered due to functional groups such as O and H contained in natural graphite, and not only hexagonal dense structure but also rumbohedral structure Structural stability is also somewhat low because it has a crystalline structure, which limits its use as an anode material despite its low price and high capacity.

However, as described above, natural graphite is coated with a specific liquid coating material and then subjected to a heat treatment process, thereby having a crystal structure satisfying Relations 1 and 2, and reducing functional groups such as O and H, which satisfies Relation 3 , it is possible to prepare a graphite negative electrode material with improved structural stability and chemical stability, thereby obtaining an anode active material with improved lifespan characteristics and high temperature storage characteristics. In addition, the high reversible capacity, which is an advantage of natural graphite, is maintained, and it can have a high initial efficiency similar to that of artificial graphite.

In the method of manufacturing a negative electrode active material according to an embodiment of the present invention, an assembly process may be further performed as a process before coating with a liquid coating material. The assembling process is a process of assembling flaky natural graphite into spherical natural graphite having an average aspect ratio of less than 2, and may be performed using a rotary processing machine. Due to the anisotropy of the material itself, flaky natural graphite deteriorates processability due to reduced fluidity in the process of mixing and slurrying with a solvent or binder during battery manufacturing, and it is difficult to form an applied layer of a predetermined thickness, so there are problems such as peeling. Since this may occur, it is preferable to granulate the natural graphite in a spherical shape.

Specifically, in the granulation process, granulation of flaky natural graphite is achieved through crushing by collision between the inner surface of the rotary processing machine and the natural graphite powder in the form of scale, friction processing between the powders, and shear processing of the powder by shear stress. It is possible to prepare spherical natural graphite particles having an aspect ratio of less than 2 and an average particle diameter of 1 to 100 μm. At this time, the speed of the rotary processing machine is 700 to 2000 rpm, and it is recommended to perform it for 10 to 30 minutes. can do.

Next, a step of coating the spherical natural graphite that has undergone the assembly process with a heavy oil-based liquid coating material may be performed. Specifically, the coating step of natural graphite according to an example of the present invention is not particularly limited as long as it is a method capable of coating a liquid coating material on a solid base material, but stress is not applied rather than a mechno fusion type coating machine. It is preferable to use a coating machine that does not have a coating machine, and specifically, it is more effective to improve performance by using a mixer for coating of a solid-liquid mixing type (mixer type) that is weakly subjected to mechanical impact. In the existing mechano-fusion coating method, which is widely used in dry coating, a shear force is applied between the base material and the coating material to coat, and at this time, the shear force causes structural defects in the spherical natural graphite, which is the base material. . On the other hand, the solid-liquid mixed coating method can minimize the structural defects that occur in the spherical natural graphite because the force transmitted to the base material is small, thereby preventing the development of the lombohedral structure inside the material. The thickness of the coating is preferably 3 to 100 nm after carbonization, and in order to effectively exhibit the performance as an anode material, it may be preferable to coat to a thickness of 5 to 20 nm.

In this case, the heavy oil-based liquid coating material may be, for example, heavy oil, heavy oil, bunker oil, or a mixture thereof. The liquid coating material can be used as it is or diluted in a solvent, and when diluted, 10 to 200 parts by weight of the solvent can be mixed with respect to 100 parts by weight of the liquid coating material, preferably 50 to 100 parts by weight of the solvent. However, the dilution ratio may be changed in consideration of the workability of the coating. At this time, the solvent may be used without particular limitation as long as it can dilute the liquid coating material well, but specifically, for example, an organic solvent such as toluene, benzene, tetrahydrofuran, quinoline, benzoquinone or acetone may be used.

Next, a heat treatment step can be performed. By heat-treating and carbonizing the natural graphite coated with the liquid coating material, it is possible to reduce the functional groups contained in the initial natural graphite and the coating material to satisfy Relation 3, and at high temperature, Structural defects are reduced by partially removing the lombohedral structure by relaxing the physical stress transferred to the base material, and the anode material manufactured in this way satisfies Relations 1 and 2.

The heat treatment step according to an example may be performed under a high temperature condition under an inert gas atmosphere such as argon (Ar), helium (He), neon (Ne), and it may be preferable to proceed over two steps. Specifically, for example, after the primary heat treatment is performed at a temperature of 450 to 800 ° C, it is preferable to perform the secondary heat treatment at a high temperature of 2800 ° C or higher, and in the case of the secondary heat treatment, preferably at a high temperature of 3000 to 3500 ° C. It may be desirable to perform If the secondary heat treatment is performed at a temperature of less than 2800° C., it may be difficult to suppress the rumbohedral structure, and the removal efficiency of the functional group may decrease, which is not good.

At this time, the carbonization yield of the liquid coating material according to an example may be 25% or more, and the upper limit is not particularly limited, but the maximum yield that the coating layer carbonized by high temperature heat treatment of 2800° C. or more can be limited to the upper limit, and specifically For example, it may be 80% or less. When the carbonization yield is less than 25%, the structural-chemical stability improvement effect by the coating layer may be insignificant.

The carbonization yield in the present invention was calculated through the following formula.

Carbonization yield (%) = (W ₀ /W _C ) × 100

In this case, W _C is the weight of the coating layer before carbonization, and W ₀ is the weight of the coating layer after carbonization.

As described above, the anode active material manufactured by the manufacturing method according to the present invention has a reversible capacity equivalent to that of conventional natural graphite and an initial efficiency equivalent to that of artificial graphite, and has improved compared to natural graphite and high-temperature storage characteristics equal to or higher than that of artificial graphite. and lifespan characteristics.

As a specific example, the negative active material may have an initial reversible capacity of 355 mAh/g or more and an initial performance of 95% or more.

In addition, a lithium ion battery including an anode active material manufactured by the manufacturing method according to an embodiment of the present invention may have excellent high-temperature storage characteristics satisfying the following relational equation (4).

[Relational Expression 4]

(CC ₀ )/C ₀ × 100 ≥ 10

In Relation 4, C is the storage capacity (%) of a lithium ion battery using the anode active material prepared by the manufacturing method of the present invention as a negative electrode, and C ₀ is a negative electrode of natural graphite manufactured by the conventional solid-state coating and 1100 ° C heat treatment method. It is the storage capacity (%) of the lithium-ion battery used as However, at this time, the storage capacity (%) is based on measuring the change in capacity by leaving it at 60°C for 21 days.

In addition, the manufacturing method according to an embodiment of the present invention may further include a purification process prior to performing the assembly process.

The purification process is not particularly limited as long as it is a method capable of purifying the purity of natural graphite to 99% by weight or more, and may be performed using a commonly used method. If the purity is less than 99% by weight, it is preferable to increase the purity as possible because structural defects of the negative electrode active material may increase due to impurities, and it is preferable to perform the purification process to have a purity of 99.9% by weight or more.

Alternatively, in the manufacturing method according to an embodiment of the present invention, a spherical negative electrode active material coated with flaky natural graphite with a coating material can be obtained by dispersing flaky natural graphite in a heavy oil-based liquid coating material and then spraying it with droplets to heat treatment. .

Specifically, it is preferable that the dispersion in which natural graphite is dispersed in the liquid coating material is mixed in such a proportion that it can be sprayed into droplets. If the mixing ratio of the liquid coating material is too small, spraying into droplets may not work properly. It may not be as good as it can be. As a specific example, the dispersion is preferably mixed with natural graphite:liquid coating material in a volume ratio of 1: 5 to 100, more preferably, in a volume ratio of 1: 10 to 50, but is not limited thereto.

The atomization of droplets may use ultrasonic atomization, electrostatic atomization, or nozzle atomization. It can be moved to heat treatment. The heat treatment conditions may be the same as those described in the heat treatment step above, and specifically, after performing the first heat treatment at a temperature of 450 to 800 ° C, the second heat treatment is performed at a high temperature of 2800 ° C. An active material can be prepared.

Such a method can further reduce the stress received by the particles by assembling and/or coating, and as the coating thickness can be controlled by controlling the size of the droplets, it is possible to obtain a coated anode active material with a very uniform thickness. There are advantages. In addition, since a spherical anode active material satisfying Relations 1 to 3 can be prepared in one step after purification, the process is very simple.

Hereinafter, a method of manufacturing a negative active material for a secondary battery according to an example of the present invention will be described in more detail. The physical properties of the lithium secondary batteries prepared through the following Examples and Comparative Examples were measured as follows.

(reversible capacity)

It is the value obtained by dividing the capacity (mAh) at the time of discharging by the mass of the active material inside the electrode by manufacturing a coin half cell using lithium metal as a counter electrode and performing charging/discharging at 0.1C/0.1C.

(Initial efficiency)

It is a percentage value obtained by dividing the discharge capacity by the charge capacity in the reversible capacity measurement method.

(lifetime characteristics)

It is a percentage value obtained by dividing the reversible capacity of each cycle by the reversible capacity of the first cycle by manufacturing a full cell (capacity 10Ah) using a commonly used commercial anode as a counter electrode and performing a cycle at 1.0C/1.0C.

(high temperature storage characteristics)

The same full cell used in the lifetime characteristic is stored in a chamber where a constant temperature is maintained at 60°C in a state where it is charged up to 95% of the total capacity, and the reversible capacity is measured according to the set measurement cycle, and the value is divided by the reversible capacity of the first cycle. is the value

[Example 1]

Spherical natural graphite having an average particle diameter of 20 μm and liquid heavy oil were put in a mixing type coating mixer to prepare natural graphite particles whose surface was coated with heavy oil. At this time, the mixing ratio of spherical natural graphite and liquid heavy oil was adjusted so that the weight of the coating layer (heavy oil layer) was 5% by weight based on the weight of the particles after carbonization. The natural graphite particles coated with heavy oil were heat-treated at 600° C. for 180 minutes and 3000° C. for 360 minutes, in two steps to prepare an anode active material, wherein the carbonization yield of the coating layer was 35%. The physical properties of the prepared negative electrode active material are shown in Table 1.

Next, the prepared negative electrode active material: styrene-butadiene rubber (SBR): carboxyl methyl cellulose (CMC) was mixed in a weight ratio of 95: 2: 3, coated on a copper thin film, dried and rolled to prepare a negative electrode. In the case of a positive electrode, a nickel-cobalt-aluminum-based (NCA) positive electrode active material: polyvinylidene fluoride (PvDF): graphite flake was mixed in a weight ratio of 92: 3: 5, followed by N-methylpyrrolidone (NMP) to prepare a positive electrode slurry. This positive electrode slurry was coated on an aluminum thin film, dried and rolled to prepare an NCA-based positive electrode.

Next, it was prepared by adjusting the capacity ratio of the positive electrode to the negative electrode to be 1:1.1, and the lithium secondary battery was assembled so that the capacity was 10 Ah ± 10%. As the electrolyte, a solution in which ethylene carbonate/ethylmethyl carbonate/diethyl carbonate was mixed in a volume ratio of 3/4/3 containing 1M LiPF ₆ and 1% by weight of vinylene carbonate (VC) was used. The physical properties of the prepared lithium secondary battery are shown in Tables 2 to 4.

[Example 2]

All processes were performed in the same manner as in Example 1 except that the heat treatment temperature was performed at 600° C. for 180 minutes and at 2800° C. for 360 minutes to prepare the negative electrode active material. In addition, the carbonization yield of the coating layer of the prepared negative electrode active material was 33%, the physical properties are shown in Table 1, and the physical properties of the prepared lithium secondary battery are shown in Tables 2 to 4.

[Example 3]

All processes were performed in the same manner as in Example 1, except that the heat treatment temperature was performed at 600° C. for 180 minutes and at 3000° C. for 240 minutes to prepare the negative electrode active material. In addition, the carbonization yield of the coating layer of the prepared negative electrode active material was 32%, the physical properties are shown in Table 1, and the physical properties of the prepared lithium secondary battery are shown in Tables 2 to 4.

[Comparative Example 1]

A natural graphite anode active material was prepared in a conventional manner. Specifically, spherical natural graphite having an average particle diameter of 20 μm and solid pitch were put into a mechano fusion mixer instead of a mixing mixer for coating to prepare natural graphite particles whose surface was coated with pitch. At this time, the mixing ratio of spherical natural graphite and solid pitch was adjusted so that the weight of the coating layer (pitch) was 5% by weight based on the weight of the particles after carbonization. The pitch-coated natural graphite particles were heat-treated in two steps at 600° C. for 180 minutes and 1100° C. for 360 minutes to prepare an anode active material. In addition, the carbonization yield of the coating layer of the prepared anode active material was 23%, and its physical properties are shown in Table 1.

Thereafter, a lithium secondary battery was manufactured by performing all processes in the same manner as in Example 1 except that the negative electrode active material was changed, and the physical properties thereof are shown in Tables 2 to 4.

[Comparative Example 2]

A commercially available artificial graphite was prepared, and its physical properties are shown in Table 1. Specifically, artificial graphite is manufactured by using coke as a raw material, heat-treating it at 3000° C., and then classifying it so that the average particle diameter is 20 μm through crushing in a collision chamber.

Thereafter, a lithium secondary battery was manufactured by performing all processes in the same manner as in Example 1 except for changing the negative electrode active material, and the physical properties thereof are shown in Tables 2 to 4.

[Comparative Example 3]

All processes were performed in the same manner as in Example 1, except that the heat treatment temperature was performed at 600° C. for 180 minutes and at 2500° C. for 360 minutes to prepare the negative electrode active material. In addition, the carbonization yield of the coating layer of the prepared negative electrode active material was 32%, the physical properties are shown in Table 1, and the physical properties of the prepared lithium secondary battery are shown in Tables 2 to 4.

I _R1 /I _hcp I _R2 /I _hcp I _{286 eV} /I _max Example 1 0.13 0.06 0.08 Example 2 0.15 0.09 0.08 Example 3 0.13 0.07 0.10 Comparative Example 1 0.44 0.21 0.17 Comparative Example 2 0.01 0.00 0.19 Comparative Example 3 0.24 0.11 0.12

(In Table 1, I _R1 is the intensity of the peak at 2θ = 43.2 to 43.5 °, which is the diffraction angle by the rumbohedral structure on XRD, and I _R2 is the diffraction angle by the rumbohedral structure on the XRD 2θ = 46 to 46.2 ° is the intensity of the peak in , I _hcp is the intensity of the peak at 2θ = 42.2 to 42.5°, which is a diffraction angle by hexagonal dense structure (hcp) on XRD, and I _{286 eV is the intensity of the peak appearing at 286 eV} on XPS, I _max is the intensity of the peak appearing at 284~285eV on XPS.)

As shown in Table 1, Examples 1 to 3 prepared by the method of the present invention used liquid heavy oil and heat treatment was performed at a high temperature of 2800° C. or higher to obtain negative active materials satisfying Relations 1 to 3. . On the other hand, in the case of Comparative Example 1, in which the negative electrode active material was prepared in the conventional manner, a mechano-fusion type mixer that receives a lot of mechanical shock by putting a solid pitch was used, and secondary heat treatment was performed at a relatively low temperature of 1100 ° C. It can be seen that the headral structure could not be suppressed and thus structurally unstable, and the functional group could not be removed. In the case of Comparative Example 2, which is artificial graphite, it was structurally very stable because there was almost no _rumbohedral structure. there was. In the case of Comparative Example 3, it was confirmed that the liquid coating material was used the same, but by performing heat treatment at a relatively low 2500° C., both physical and chemical stability were somewhat inferior compared to the present invention.

Reversible capacity (mAh/g) Initial efficiency (%) Example 1 365 96.0 Example 2 361 95.8 Example 3 360 95.7 Comparative Example 1 364 92.7 Comparative Example 2 350 96.6 Comparative Example 3 357 94.2

As shown in Table 2, in the case of Examples 1 to 3, it can be confirmed that the reversible capacity is 360 mAh/g or more, and the initial efficiency is 95.7% or more, showing very good performance. As such, it was possible to have a high capacity by using natural graphite as a raw material for the negative electrode active material, and also to have high initial efficiency, which is an advantage of artificial graphite. That is, it can be seen that the present invention can obtain an excellent anode active material having both the advantages of artificial graphite and the advantages of natural graphite.

Storage capacity (%) 0 times 10 episodes Episode 20 30 episodes 40 episodes 50 episodes Example 1 100 99.9 99.7 99.6 99.3 98.9 Example 2 100 99.9 99.6 99.5 99.1 98.7 Example 3 100 99.9 99.5 99.4 99.0 98.5 Comparative Example 1 100 99.7 99.1 98.8 98.4 98.1 Comparative Example 2 100 99.5 99.2 99.0 98.8 98.3 Comparative Example 3 100 99.5 99.1 98.8 98.4 98.0

Table 3 confirms the lifespan characteristics of the secondary battery. A full cell (capacity 10Ah) was manufactured using a commonly used commercial positive electrode as a counter electrode, and the cycle was performed at 1.0C/1.0C to obtain the reversible capacity of each cycle. It is a percentage value divided by the reversible capacity of the first cycle. As shown in Table 3, it was confirmed that Examples 1 to 3 showed a high capacity retention rate of 98.5% or more even after 50 charging and discharging times.

Storage capacity (%) (C ₂₁ -C ^* )/C ^* Day 0 (C ₀ ) 7 days (C ₇ ) 14 days (C ₁₄ ) Day 21 (C ₂₁ ) Example 1 100 93.8 88.2 84.0 0.129 Example 2 100 93.1 86.8 82.6 0.110 Example 3 100 93.5 87.3 83.0 0.116 Comparative Example 1 100 85.4 79.0 74.4 0 Comparative Example 2 100 93.7 85.1 81.8 0.099 Comparative Example 3 100 89.9 82.2 76.8 0.028

Table 4 confirms the high-temperature storage characteristics of the secondary battery. The same full cell used in the lifespan characteristic is stored in a chamber where a constant temperature of 60°C is maintained in a state where it is charged up to 95% of the total capacity, and the reversible capacity according to the set measurement cycle. It is the value obtained by measuring , and dividing the value by the reversible capacity of the first cycle. At this time, in Table 4, C ₂₁ is the storage capacity (%) when each lithium secondary battery is stored for 21 days, and C ^* is the storage capacity (74.4%) of Comparative Example 1 among them.

As shown in Table 4, Examples 1 to 3 were stored at 60 ° C. for 21 days, and then the storage capacity increased by 10% or more compared to the lithium secondary battery of Comparative Example 1 prepared using the conventional natural graphite It can be seen that by having a very excellent high-temperature storage characteristics.

Claims (14)

mixing natural graphite having a purity of 99.9% or more and a heavy oil-based liquid coating material at room temperature with a solid-liquid mixing method, and coating the natural graphite with the heavy oil-based liquid coating material; and
heat-treating to satisfy the following relation (3);
A method of manufacturing a negative active material for a secondary battery for preparing a negative active material satisfying the following Relations 1 and 2, including:
[Relational Expression 1]
0 ≤ I _R1 /I _hcp ≤ 0.15
[Relational Expression 2]
0 ≤ I _R2 /I _hcp ≤ 0.09
[Relational Expression 3]
I _{286 eV} /I _max ≤ 0.1
(In Relations 1 or 2, I _R1 is the intensity of the peak at 2θ = 43.2 to 43.5 °, which is the diffraction angle of the rumbohedral structure on the XRD, and I _R2 is the diffraction angle of the rumbohedral structure on the XRD 2θ = 46 The intensity of the peak at ~46.2°, I _hcp is the intensity of the peak at 2θ = 42.2~42.5°, which is the diffraction angle by the hexagonal dense structure (hcp) on the XRD,
In Relation 3, I _{286 eV} is the intensity of the peak appearing at 286 eV on XPS, and I _max is the intensity of the peak appearing at 284 ~ 285 eV on XPS.) The method of claim 1,
A method of manufacturing a secondary battery negative active material having a coating thickness of 3 to 100 nm by the coating. The method of claim 1,
The heavy oil-based liquid coating material is heavy oil, heavy oil, bunker oil, or a mixture thereof. The method of claim 1,
The heavy oil-based liquid coating material is a method of manufacturing a secondary battery negative active material having a carbonization yield of 25% or more. The method of claim 1,
The heat treatment is a method of manufacturing a negative active material for a secondary battery is performed at 2800 ℃ or more. The method of claim 1,
The negative active material is a method of manufacturing a negative active material for a secondary battery that satisfies the following relational formula (4).
[Relational Expression 4]
(CC ₀ )/ C ₀ × 100 ≥ 10
(In Relation 4, C is the storage capacity (%) of a lithium ion battery using the negative electrode active material prepared by the manufacturing method of the present invention as the negative electrode, and C ₀ is the lithium ion prepared in the conventional manner using natural graphite as the negative electrode This is the storage capacity (%) of the battery, however, the storage capacity (%) is based on the measurement of capacity change by leaving it at 60℃ for 21 days.) A negative active material for a secondary battery prepared by the method of any one of claims 1 to 6. A negative active material for a secondary battery that satisfies Relations 1, 2 and 3.
[Relational Expression 1]
0 ≤ I _R1 /I _hcp ≤ 0.15
[Relational Expression 2]
0 ≤ I _R2 /I _hcp ≤ 0.09
[Relational Expression 3]
I _{286 eV} /I _max ≤ 0.1
(In Relations 1 or 2, I _R1 is the intensity of the peak at 2θ = 43.2 to 43.5 °, which is the diffraction angle of the rumbohedral structure on the XRD, and I _R2 is the diffraction angle of the rumbohedral structure on the XRD 2θ = 46 The intensity of the peak at ~46.2°, I _hcp is the intensity of the peak at 2θ = 42.2~42.5°, which is the diffraction angle by the hexagonal dense structure (hcp) on the XRD,
In Relation 3, I _{286 eV} is the intensity of the peak appearing at 286 eV on XPS, and I _max is the intensity of the peak appearing at 284 ~ 285 eV on XPS) 9. The method of claim 8,
The negative active material is a base material of natural graphite; and a coating layer for coating the base material, wherein the coating layer contains a carbide of a heavy oil-based liquid coating material. 10. The method of claim 9,
The base material is an anode active material for a secondary battery of spherical natural graphite having an average aspect ratio of less than 2. 10. The method of claim 9,
The coating layer is an anode active material for a secondary battery further containing flaky natural graphite. 10. The method of claim 9,
The thickness of the coating layer is 3 to 100nm anode active material for a secondary battery. A lithium secondary battery comprising the negative active material for a secondary battery according to any one of claims 8 to 12. 14. The method of claim 13,
The lithium secondary battery is a lithium secondary battery having a capacity retention rate of 98.5% or more in 50 charge/discharge cycles.

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