KR101583639B1 - Anode active material, method for manufacturing the same and secondary battery comprising the same - Google Patents

Abstract

A negative electrode active material is provided. According to an embodiment, the negative electrode active material comprises: a crystalline carbon particle; a carbon coating layer having high surface roughness in comparison with the crystalline carbon particle; and a metal particle carried in the crystalline carbon layer. The present invention provides a negative electrode and a secondary battery, with improved capacity and cycle properties.

Description

Field of the Invention [0001] The present invention relates to an anode active material, a method for producing the same, and a secondary battery including the anode active material,

The present invention relates to a negative electrode active material, a method for producing the negative electrode active material, and a secondary battery including the same.

Portable electronic devices have become lighter and more sophisticated, and output characteristics of driving power sources are gradually increasing for long-time use of the devices. Various kinds of secondary batteries such as a lead-acid battery, a nickel-metal hydride battery and a lithium secondary battery are used. The lithium secondary battery is widely used in portable electronic devices because of its high operating voltage and high energy density per unit weight.

Currently, graphite, which is an interlayer material, is most widely used as an anode active material of a lithium secondary battery. Lithium ions can be reversibly intercalated and deintercalated in the interlayer of graphite. Such intercalation / deintercalation can be repeated hundreds or thousands of times and is relatively inexpensive and widely used as an anode active material. However, the theoretical capacity is 372 mAh / g .

Research has been actively conducted to use metal and non-metal materials that form compounds by electrochemically bonding with lithium ions to improve the capacity of the negative electrode active material.

In the case of silicon (Si), Li ₄ Si compound can be reversibly formed by reacting with lithium, and when it is converted to a capacity, it is about 4200 mAh / g, which is about 11 times higher than that of graphite. In the case of tin (Sn), a compound of lithium and Li ₂₂ Sn ₅ can be formed. The theoretical capacity is about 993 mAh / g, which corresponds to about 2.7 times the capacity of graphite. In addition, various kinds of metals such as antimony (Sb), aluminum (Al), and bismuth (Bi) have been studied as candidates for negative electrode active materials.

The use of metal particles as a negative electrode active material of a lithium secondary battery has the following disadvantages. When graphite is electrochemically reacted with lithium ions to form a compound, a volume expansion of about 1.1 to 1.2 times occurs. However, when metal particles are electrochemically combined with lithium ions to form a compound, silicon (Si ), The volume expands to a maximum of about 4.12 times, which causes volume expansion and contraction repeatedly during charging and discharging to change the crystal structure and cause particle collapse, and the capacity gradually decreases.

The above conventional techniques use a mechanical mixing or the like to place metal particles on the surface of the crystalline carbon particles. The metal particles are coated on the surface of the crystalline carbon particles with a polymer resin for coating with amorphous carbon, and then subjected to a heat treatment at 700 ° C or higher . Through such a process, the crystalline carbon may be physically influenced by mechanical action, or the growth of metal particles may be induced during the heat treatment at a high temperature, which may affect cycle life as a negative electrode active material of a lithium secondary battery.

SUMMARY OF THE INVENTION The present invention provides a negative electrode active material having improved capacity and cycle characteristics and a method for producing the same.

Another object of the present invention is to provide a secondary battery having improved capacity and cycle characteristics.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method of manufacturing the same.

According to an aspect of the present invention, there is provided an anode active material comprising crystalline carbon particles; A carbon coating layer having a surface roughness larger than that of the crystalline carbon particles and disposed on the surface of the crystalline carbon particles; And metal particles supported on the carbon coating layer.

The crystalline carbon particles may be microparticles. The microparticles are particles having a particle size of several micrometers (占 퐉) to several hundreds of micrometers. In a non-limiting example, the crystalline carbon particles may have a size of greater than 1 micrometer to less than 20 micrometers. As the size of the crystalline carbon particles increases, the crystalline carbon particles can act as a resistance against lithium ions in the charging / discharging process of the lithium secondary battery, and the capacity (mAh / L) per unit volume of the lithium secondary battery can be lowered, In another non-limiting example, the size of the crystalline carbon particles may be less than 10 micrometers and may be, for example, greater than or equal to 5 micrometers and less than or equal to 10 micrometers.

The crystalline carbon particles may be composed of at least one carbon isotope selected from the group consisting of graphite, hard carbon, soft carbon, and mixtures thereof.

The carbon coating layer may have a larger surface roughness than the crystalline carbon particles. The carbon coating layer may be an amorphous carbon coating layer. The carbon coating layer may cover all or part of the surface of the crystalline carbon particles.

The thickness of the carbon coating layer is not particularly limited, but in a non-limiting example, the carbon coating layer may have a thickness of 1 nm or more and 900 nm or less.

Within the thickness range of the carbon coating layer, the carbon coating layer may not act as a resistance against lithium ions in the charge / discharge cycle of the lithium secondary battery, and the capacity (mAh / L) per unit volume of the lithium secondary battery may be minimized.

Also, since the increase of the irreversible reaction by the carbon coating layer can be suppressed within the thickness range of the carbon coating layer, the increase of the initial irreversible capacity of the lithium secondary battery can be minimized.

The metal particles may be selected from the group consisting of Si, Sn, Pb, In, As, Al, Sb, Se, (Ag), sulfur (S), bismuth (Bi), and alloys thereof.

The metal particles are nanoparticles. The metal particles may have a size of 200 nm or less. For example, the metal particles have a size of 2 nm or more and 200 nm or less.

The metal particles may be at least 5 parts by weight and not more than 70 parts by weight based on 100 parts by weight of the crystalline carbon particles.

The metal particles may be disposed on the surface of the carbon coating layer.

The carbon coating layer may include a first region and a second region, and the first region may have a higher content of the metal particles per unit area than the second region.

According to an aspect of the present invention, there is provided a method of manufacturing an anode active material, the method comprising: mixing a crystalline carbon particle and an organic compound in a first agitation step, and heat-treating the first agitated material to prepare a carbon-based anode active material precursor; step; And a step of secondly stirring the carbon-based anode active material precursor and the metal-based anode active material precursor, and adding a reducing agent to the second agitated product.

The organic compound may be an organic polymer compound. As a non-limiting example, the organic polymer compound includes a vinyl resin, a cellulose resin, a phenol resin, a pitch, a tar resin or a mixture thereof.

The carbon-based anode active material precursor may have a structure in which the carbon coating layer having a surface roughness larger than that of the crystalline carbon particles is positioned on the surface of the crystalline carbon particles. The carbon-based anode active material precursor may have a structure in which the entire surface of the crystalline carbon particles is covered with the carbon coating layer having a larger surface roughness than the crystalline carbon particles.

The metal-based anode active material precursor may be a metal chloride, a metal nitrate, a metal sulfate, a metal iodide, a metal acetate, or a mixture thereof.

The reducing agent may be NaBH ₄ , NaAlH ₄ , LiBH ₄ , LiAlH ₄ , hydrazine, aldehyde, methanol, ethanol, polyol or a mixture thereof.

The method for manufacturing the negative electrode active material may further include removing the residual reducing agent through filtration and washing processes.

The present invention also provides a secondary battery comprising the above-mentioned negative electrode active material. The secondary battery includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and the negative electrode includes the negative electrode active material. In a non-limiting example, the secondary battery may be a lithium secondary battery.

The details of other embodiments are included in the detailed description and drawings.

Embodiments of the present invention can exhibit at least the following effects.

It is possible to provide a negative electrode active material and a secondary battery with improved capacity and cycle characteristics.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

1 is a schematic cross-sectional view of an anode active material according to an embodiment of the present invention.
2 is an electron micrograph of an anode active material according to an embodiment of the present invention.
3 is an electron micrograph of graphite particles.
FIGS. 4 to 5 are schematic cross-sectional views of a process for producing a negative electrode active material according to an embodiment of the present invention.
6 is a charge-discharge voltage-capacity curve of a coin cell including a negative electrode active material according to an embodiment of the present invention.
7 to 9 are charge-discharge voltage-capacity curves of a coin cell including negative electrode active materials according to comparative examples.
10 is a graph showing a comparison of charge-discharge cycle characteristics of a coin cell including a negative active material according to an embodiment of the present invention and a negative active material according to a comparative example.
11 is a schematic cross-sectional view of a negative electrode active material according to another embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification. The dimensions and relative sizes of layers and regions in the figures may be exaggerated for clarity of illustration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and experimental examples.

1 is a schematic cross-sectional view of an anode active material according to an embodiment of the present invention.

1, the negative electrode active material 100 includes a crystalline carbon particle 101, a carbon coating layer 102, and metal particles 103. As shown in Fig. The carbon coating layer 102 is disposed on the surface of the crystalline carbon particles 101 and the metal particles 103 are supported on the carbon coating layer 102. The metal particles 103 may be disposed mainly on the surface of the carbon coating layer 102.

The crystalline carbon particles 101 may be a layered or porous carbon material, and lithium ions may be reversibly intercalated or deintercalated into intercalation or pore spaces of the crystalline carbon particles. For example, the crystalline carbon particles 101 may be composed of at least one carbon isotope selected from the group consisting of graphite, hard carbon, soft carbon, and mixtures thereof. Graphite includes both natural graphite and artificial graphite.

The shape of the crystalline carbon particles 101 is not particularly limited, and examples thereof include spherical, elliptical, plate-like, cylindrical, and the like. The crystalline carbon particles may be microparticles. The microparticles are particles having a particle size of several micrometers (占 퐉) to several hundreds of micrometers. In a non-limiting example, the crystalline carbon particles may have a size of greater than 1 micrometer to less than 20 micrometers. In another non-limiting example, the crystalline carbon particles may have a size of greater than or equal to 5 micrometers and less than or equal to 10 micrometers.

The surface roughness of the carbon coating layer 102 may be larger than that of the crystalline carbon particles 101. The rough surface of the carbon coating layer 102 provides a larger specific surface area than the crystalline carbon particles 101. The rough surface of the carbon coating layer 102 provides a site where the metal particles 103 can bind. The rough surface of the carbon coating layer 102 provides a strong binding force to the metal particles 103. This will be described below in detail with reference to FIG. 2 and FIG.

The carbon coating layer 102 may be an amorphous carbon coating layer capable of suppressing the decomposition of the electrolyte. The amorphous carbon coating layer suppresses the decomposition of the electrolyte and can provide a secondary cell of high efficiency.

The carbon coating layer 102 may cover the whole surface of the crystalline carbon particles 101. In other words, the crystalline carbon particles 101 and the carbon coating layer 102 may be formed in a core-shell structure. The core-shell structure can minimize or prevent the reaction of the crystalline carbon particles 101 with the electrolyte.

The thickness of the carbon coating layer 102 can be determined within a range in which lithium ions can permeate, and is not particularly limited. In a non-limiting example, the thickness of the carbon coating layer 102 may be in the range of more than a few nanometers to a few hundred nanometers, specifically, in the range of 1 nm or more and 900 nm or less.

The carbon coating layer 102 can be formed on the surface of the crystalline carbon particles 101 by a method of carbonizing the organic compound by heat treatment or the like. The manufacturing method will be described in detail below.

The metal particles 103 are not particularly limited as long as they are capable of reacting with lithium ions in the charging process of the secondary battery to form a lithium-metal alloy and can be converted into metal particles 103 by the elimination of lithium ions during the discharge process of the secondary battery (Si), tin (Sn), lead (Pb), indium (In), arsenic (As), aluminum (Al), antimony (Sb), selenium (Se), phosphorous ), Silver (Ag), sulfur (S), bismuth (Bi), alloys thereof, and the like.

The metal particles 103 have a size of 2 nm or more and 200 nm or less. The metal particles 103 can improve the cycle characteristics of the secondary battery at a size of 2 nm or more and 200 nm or less. Specifically, when the size of the metal particles 103 exceeds 200 nm, cracks may be generated in the metal particles 103 during the charge and discharge of the secondary battery. In other words, when the size of the metal particles 103 exceeds 200 nm, the metal particles 103 can be pulverized during charging and discharging of the secondary battery. The pulverization of the metal particles 103 can reduce the cycle characteristics of the secondary battery.

The content of the metal particles 103 may be determined in a range of 5 parts by weight or more and 70 parts by weight or less based on 100 parts by weight of the crystalline carbon particles (101).

The metal particles 103 are carried on the carbon coating layer 102, and can be disposed mainly on the rough surface of the carbon coating layer 102. The physical mutual interaction between the rough surface of the carbon coating layer 102 and the metal particles 103 may allow the metal particles 103 to be strongly bonded to the carbon coating layer 102. [ 2 is an electron micrograph of an anode active material according to an embodiment of the present invention. 3 is an electron micrograph of graphite particles.

Specifically, FIG. 2 is an electron micrograph of a negative electrode active material having a carbon coating layer formed on the surface of graphite particles and tin (Sn) nanoparticles bound to the surface of the carbon coating layer, and FIG. 3 is an electron micrograph .

Referring to FIGS. 2 and 3, it can be seen that the carbon coating layer has rough surfaces as compared with graphite particles. The rough surface of the carbon coating layer provides strong adhesion to the tin nanoparticles. On the other hand, the surface of the graphite particles can be confirmed to be smooth as compared with the carbon coating layer. The physical mutual binding force between the smooth surface of the graphite particles and the tin nanoparticles is significantly lower than the physical mutual binding force between the rough surface of the carbon coating layer and the tin nanoparticles. Therefore, the tin nano-particles are hardly adhered to the smooth surface of the graphite particles, and the tin nano-particles can be separated from the surface of the graphite particles in the charge-discharge process of the secondary battery. This phenomenon not only degrades the cycle characteristics of the secondary battery but also causes a reduction in capacity.

On the other hand, a carbon coating with a rough surface can provide strong adhesion to the tin nanoparticles even during charging and discharging. Therefore, the secondary battery using the negative electrode active material of FIG. 2 according to an embodiment of the present invention as a negative electrode may have improved cycle characteristics and capacity characteristics as compared with a secondary battery using graphite as a negative active material.

Hereinafter, a method of manufacturing the negative electrode active material 100 will be described in detail.

FIGS. 4 to 5 are schematic cross-sectional views of a manufacturing process of the negative electrode active material 100. FIG.

4 schematically shows the step of forming the organic compound coating layer 106 on the surface of the crystalline carbon particles 101. In FIG. 5 schematically shows the step of forming the carbon coating layer 102 on the surface of the crystalline carbon particles 101. As shown in FIG.

4 and 5, the step of forming the organic compound coating layer 106 on the surface of the crystalline carbon particles 101 may include a first step of stirring the crystalline carbon particles 101 and an organic compound, 1 < / RTI >

Since the crystalline carbon particles 101 have been described above, a detailed description thereof will be omitted.

The organic compound is not particularly limited as a precursor for forming the carbon coating layer 102. The organic compound may be an organic polymer compound. As a non-limiting example, the organic polymer compound may be a vinyl resin, a cellulose resin, a phenol resin, a pitch, a tar resin or a mixture thereof.

The carbon-based anode active material precursor in which the carbon coating layer 102 is formed on the surface of the crystalline carbon particles can be produced by heat-treating the first stirred material. The heat treatment temperature, time and the like are not particularly limited, and in a non-limiting example, the heat treatment temperature may be 500 ° C or higher, and the heat treatment may be conducted in an inert gas atmosphere. In a non-limiting example, the inert gas atmosphere may be a nitrogen atmosphere.

Referring to FIGS. 1 and 5, after the process shown in FIG. 5, metal particles 103 may be carried on the surface of the carbon coating layer 102. The step of supporting the metal particles 103 on the surface of the carbon coating layer 102 may include: a second step of stirring the carbon-based anode active material precursor and the metal-based anode active material precursor; And adding a reducing agent to the second stirred material. The negative electrode active material of FIG. 1 can be manufactured through the step of supporting the metal particles 103 on the surface of the carbon coating layer 102.

In the method of manufacturing an anode active material according to an embodiment of the present invention, the metal particles 103 may be supported on the surface of the carbon coating layer 102 by reducing the metal anode active material precursor to metal. The method for producing the negative electrode active material according to the present invention can produce the metal particles 103 on the carbon coating layer 102 by the reduction method in a solution state without a high temperature heat treatment process.

Specifically, the metal particles 103 may be formed in solution by a reducing agent at a temperature of 100 DEG C or lower and physically bonded to the surface of the carbon coating layer 102. [ Therefore, it is possible to prevent or suppress the growth of the metal particles 103 during the manufacturing process.

The metal particles 103 are electrochemically reacted directly with lithium ions to form a lithium-metal alloy upon charging of the secondary battery, and are reversibly separated from lithium ions and converted into metal particles 103 at the time of discharging.

The metal-based anode active material precursor is not particularly limited as long as it can serve to provide the metal particles 103, but in a non-limiting example, metal chloride, metal nitrate, metal sulfate, metal Iodide, metal acetate, or a mixture thereof.

The reducing agent as long as it can reduce the metal-based negative electrode active material precursor of a metal particle 103 is not particularly limited, but in non-limiting example, NaBH _4, NaAlH _4, LiBH _4, LiAlH _4, hydrazine (hydrazine), aldehyde (aldehyde ), Methanol, ethanol, polyol, or a mixture thereof.

The method for manufacturing the negative electrode active material may further include removing the residual reducing agent through filtration and washing processes.

On the other hand, the negative electrode active material can be manufactured such that the metal particles 103 are positioned inside the carbon coating layer 102. As a non-limiting example, the first stirring step of FIG. 4 may be carried out by stirring the crystalline carbon particles, the organic compound, and the metal particles together, followed by heat treatment. In this case, however, the metal particles may grow in the heat treatment step, and metal particles exceeding 200 nm may be generated. Metal particles exceeding 200 nm may cause separation of the lithium-metal alloy or cracking of the metal particles during charging and discharging, as described above.

6 to 10 are experimental results of a coin cell including an anode active material according to an embodiment of the present invention.

Specifically, FIG. 6 is a charge-discharge voltage-capacity curve of a coin cell including a negative electrode active material according to an embodiment of the present invention. 7 to 9 are charge-discharge voltage-capacity curves of a coin cell including negative electrode active materials according to comparative examples. 10 is a graph showing a comparison of charge-discharge cycle characteristics of a coin cell including a negative active material according to an embodiment of the present invention and a negative active material according to a comparative example.

6 to 10, an example of manufacturing coin cells including an anode active material according to an embodiment of the present invention, an experimental example, and the like will be described in detail.

≪ Example 1 >

1.0 g of C ₁₂ H ₂₂ O ₁₁ (Aldrich Co) was dissolved in distilled water and 1.8 g of graphite (Posco Chemtech) was added. The distilled water was slowly evaporated with stirring at 60 ° C and C ₁₂ H ₂₂ O ₁₁ was coated on the graphite surface. The graphite coated with C ₁₂ H ₂₂ O ₁₁ was then dried in an oven at 80 ° C for 2 hours to completely remove the solvent.

The graphite coated with C ₁₂ H ₂₂ O ₁₁ was placed in a tube furnace and subjected to heat treatment at 700 ° C for 2 hours under a nitrogen atmosphere to carbonize C ₁₂ H ₂₂ O ₁₁ . As a result, an amorphous carbon coating layer of 10% by weight was formed on the graphite surface.

0.7 g of graphite in which an amorphous carbon coating layer was formed was dispersed in distilled water, and SnCl ₂ (Aldrich Co) were added and stirred. 250 ml of a 0.2 M NaBH ₄ solution as a reducing agent was slowly added thereto. After all of the reducing agent solution was added, the Sn nanoparticles were allowed to be carried on the amorphous carbon coating layer on the graphite surface while stirring for 12 hours. In order to remove residual reducing agent, filtration and washing were repeated, followed by drying to prepare a negative electrode active material carrying 20 wt% of Sn nanoparticles on a weight basis.

The prepared negative electrode active material and polyvinylidene fluoride (PVDF, Arkema) were mixed in NMP (N-methyl-2-pyrrolidone, Aldrich) solution at a weight ratio of 90:10 to prepare a negative electrode active material slurry, The entire foil collector was cast by Dr. blade method, followed by drying and pressing to prepare a negative electrode.

The anode was cut into 1 cm ² and placed in a coin cell 2032 (Hoshen). A polypropylene porous film (Celgard 2400) as a separator and a lithium metal foil were placed thereon, and 1M LiPF ₆ dissolved ethylene A coin cell was prepared by adding a mixed solution of ethylene carbonate (EC), diethylene carbonate (DEC) and ethyl methyl carbonate (EMC).

≪ Comparative Example 1 &

Except that the formation of the amorphous carbon coating layer using C ₁₂ H ₂₂ O ₁₁ was carried out in the same manner as in Example 1, to thereby prepare an anode active material having Sn nanoparticles on the surface of graphite. Thereafter, a coin cell was produced in the same manner as in Example 1.

≪ Comparative Example 2 &

A coin cell was fabricated in the same manner as in Example 1 using graphite as the negative electrode active material.

≪ Comparative Example 3 &

The negative electrode active material having an amorphous carbon coating layer formed on the surface of graphite was prepared using the same method as in Example 1 except for the loading of Sn nanoparticles. A coin cell was fabricated in the same manner as in Example 1.

<Experimental Example>

Charge-discharge experiments were carried out using the coin cells of Example 1 and Comparative Examples 1 to 3. Charging and discharging tests were conducted 30 times at 0.01 to 1.0 V (vs. Li / Li +). The first discharge capacity, the charge-discharge efficiency and the capacity retention rate after 30 cycles of the charge-discharge test results of Example 1 and Comparative Examples 1 to 3 are shown in Table 1 below.

division First discharge capacity
(mAh / g) First charge / discharge efficiency
(%) Capacity retention rate (%)
(After 30 charge / discharge cycles) Example 1 479 80.2 99.7 Comparative Example 1 447 82.5 89.5 Comparative Example 2 351 80.3 99.8 Comparative Example 3 318 64.4 99.5

As shown in Table 1 and Figs. 7 to 11, the first discharge capacity of Example 1 was about 27.8% higher than the theoretical graphite capacity (372 mAh / g) of general graphite, and the first charge- Respectively. Also, after 30 cycles, the capacity retention rate maintained 99.7% of the initial capacity value and the cycle life was also excellent.

When the capacity of graphite, which is carbon particles in Example 1, is assumed to be 372 mAh / g, the capacity of the metal nanoparticle Sn alone can be calculated to be about 850 mA / g, which is equivalent to the theoretical capacity of Sn (993 mAh / g) 85.6%.

The initial capacity of graphite coated with amorphous carbon was as low as 318 mAh / g, but as shown in FIG. 11, the capacity increased to about 380 mAh / g in the following cycle. It is due to the reaction that the ions are inserted and desorbed.

11 is a schematic cross-sectional view of a negative electrode active material according to another embodiment of the present invention.

Referring to FIG. 11, the negative electrode active material according to another embodiment may include the carbon coating layer 102 in the first region R1 and the second region R2. The content of the metal particles 103 in the first region R1 may be higher than that in the second region R2.

Meanwhile, one embodiment of the present invention provides a secondary battery (not shown) including the negative electrode active material of FIG. 1 or FIG. The secondary battery includes a positive electrode (not shown), a negative electrode (not shown), a separator (not shown) disposed between the positive and negative electrodes, and an electrolyte, and the negative electrode includes the negative electrode active material shown in FIG. 1 or FIG. In a non-limiting example, the secondary battery may be a lithium secondary battery.

The anode can include, in a non-limiting example, the following cathode active material. However, it is not limited thereto. The cathode active material can be produced by a solid phase method, a hydrothermal method, a sol-gel method, or the like.

The positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + y} Mn _{2 - y} O ₄ (where y is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li2CuO2); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula _{LiNi 1 - y M y O 2} ( where, the M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, y = 0.01 ~ 0.3 Im) Ni site type lithium nickel oxide which is represented by; Formula _{LiMn 2 - y M y O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, y = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like.

The separator may be, for example, an olefinic polymer such as polypropylene, which is chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like; Kraft paper and the like can be used. Representative examples currently on the market include Celgard® 2400, 2300 (from Hoechest Celanese Corp.), polypropylene separator (from Ube Industries Ltd. or Pall RAI), and polyethylene series (from Tonen or Entek).

The electrolyte may be a non-aqueous electrolyte, a non-aqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte, or the like.

Examples of the nonaqueous electrolyte include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate , Gamma -butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, Diethyl ether, formamide, dimethyl formamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane A derivative thereof, a sulfone, a methylsulfolane, a 1,3-dimethyl-2-imidazolidinone, a propylene carbonate derivative, a tetrahydrofuran derivative, ether, methyl pyrophosphate, ethyl propionate, a polyethylene derivative, Polypropylene oxide Li ₃ N, Li ₅ , Li ₅ NI ₂ , Li ₃ , Li ₂ O ₃ , Li ₂ O, Li ₂ O, Li ₂ O, _{N-LiI-LiOH, LiSiO 4} , LiSiO 4 -LiI-LiOH, Li 2 SiS 3, Li 4 SiO 4, Li 4 SiO 4 , etc. _{-LiI-LiOH, Li 3 PO 4} -Li 2 S-SiS 2 can be used But are not limited to these.

Other methods for producing a lithium secondary battery and the like are known in the related art, so a detailed description thereof will be omitted.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is to be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

100: anode active material
101: crystalline carbon particles
102: amorphous carbon coating layer
103: metal particles
106: organic compound coating layer

Claims (16)

Crystalline carbon particles;
A carbon coating layer having a surface roughness larger than that of the crystalline carbon particles and disposed on the surface of the crystalline carbon particles;
Metal particles disposed only on the surface of the carbon coating layer;
And a negative electrode active material. The method according to claim 1,
Wherein the carbon coating layer is an amorphous carbon coating layer. The method according to claim 1,
Wherein the crystalline carbon particles have a size of 1 micrometer (占 퐉) or more to 20 占 퐉 or less. The method according to claim 1,
Wherein the crystalline carbon particles comprise at least one carbon isotope selected from the group consisting of graphite, hard carbon, soft carbon, and mixtures thereof. The method according to claim 1,
Wherein the carbon coating layer covers all or a part of the surface of the crystalline carbon particles. The method according to claim 1,
The metal particles may be selected from the group consisting of Si, Sn, Pb, In, As, Al, Sb, Se, (Ag), sulfur (S), bismuth (Bi), and alloys thereof. The method according to claim 1,
Wherein the metal particles have a size of 2 nm or more and 200 nm or less. delete The method according to claim 1,
Wherein the carbon coating layer comprises a first region and a second region,
Wherein the first region has a higher content of the metal particles per unit area than the second region. Preparing a carbon-based anode active material precursor by firstly stirring the crystalline carbon particles and the organic compound and heat-treating the first stirred material; And
Mixing the carbon-based anode active material precursor and the metal-based anode active material precursor with a second agitation, and adding a reducing agent to the second agitated material;
And a negative electrode active material. 11. The method of claim 10,
The reducing agent is not less than _{NaBH 4, NaAlH 4, LiBH 4} , LiAlH 4, hydrazine (hydrazine), aldehyde (aldehyde), methanol (methanol), ethanol (ethanol), polyols (polyol) and one selected from the group consisting of A method for producing an anode active material. 11. The method of claim 10,
The metal-based anode active material precursor may be at least one selected from the group consisting of a metal chloride, a metal nitrate, a metal sulfide, an iodide, a metal acetate, A method for producing an active material. 11. The method of claim 10,
Wherein the organic compound is an organic polymer compound. 14. The method of claim 13,
Wherein the organic polymer compound is at least one selected from the group consisting of a vinyl resin, a cellulose resin, a phenol resin, a pitch, a tar resin, and combinations thereof. 11. The method of claim 10,
And removing the residual reducing agent through a filtration and washing process. A negative electrode comprising the negative electrode active material according to any one of claims 1 to 7 and 9;
anode; And
A separation membrane disposed between the cathode and the anode;
And a secondary battery.

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