KR20240047128A - Anode active material for lithium battery, method for preparing the same, and rechargeable lithium battery comprising the same - Google Patents

Abstract

The present invention provides primary particles having a core portion containing metal particles and a shell portion containing amorphous carbon; and an ion conductive material surrounding a plurality of the primary particles; It relates to a negative electrode active material for a lithium secondary battery comprising secondary particles formed including a method for manufacturing the same, and an electrode and a lithium secondary battery comprising the same.

Description

Anode active material for lithium battery, manufacturing method thereof, and lithium secondary battery comprising the same {Anode active material for lithium battery, method for preparing the same, and rechargeable lithium battery comprising the same}

The present invention relates to a negative electrode active material for lithium batteries, a manufacturing method thereof, and a lithium secondary battery containing the same. Specifically, the present invention relates to a negative electrode active material containing an ion conductive material for a next-generation lithium battery that enables stable long life characteristics and rapid charge/discharge characteristics by applying a negative electrode active material containing an ion conductive material. It relates to cathode active materials.

Lithium Ion Battery (LIB) has high energy density and is easy to design, so it has been adopted and used as a main power source for mobile electronic devices. In the future, it will be applied to electric vehicles or renewable energy power storage devices. The scope is becoming wider.

In order to apply it to new application fields, research on LIB materials with characteristics such as higher energy density and longer lifespan is continuously required. In particular, in the case of cathode materials, research has been conducted on various materials such as carbon, silicon, tin, and germanium.

Among these, silicon-based anode materials have received much attention because they have a much higher theoretical capacity compared to currently commercialized graphite anode materials. However, in silicon-based anode materials, electrochemical properties deteriorate due to the formation of an unstable SEI (Solid Electrolyte Interphase) layer due to a side reaction between the silicon surface and the electrolyte, or the electrode material is pulverized due to internal stress due to rapid volume expansion that occurs during charging and discharging. There are problems that arise.

Meanwhile, since conventional lithium-ion batteries mainly used flammable organic liquid electrolytes as electrolytes, there were safety problems such as ignition and explosion due to overheating, so recently, all-solid state batteries using non-flammable solid electrolytes have been developed. ) is attracting attention. However, in all-solid-state batteries, a lithium ion deficiency layer is formed at the interface between the electrode active material and the sulfide-based electrolyte, resulting in large interfacial resistance, resulting in problems such as reduced battery capacity, reduced output characteristics, and shortened charge and discharge life.

In order to solve the structural problems of the silicon-based anode material and the problem of solid electrolyte interface resistance mentioned above, various material design methods and process methods were proposed, but only improvements in each element were considered, so there were limitations in applying them to actual commercialization. Accordingly, in order to achieve actual commercialization, the manufacturing method and structural design of electrode materials and solid electrolytes must be comprehensively considered.

The present invention was developed to solve the above problems, and is a negative electrode active material for a secondary battery that has high capacity and high energy density and has long life characteristics that enable stable and rapid charge/discharge behavior due to low interfacial resistance between the electrode active material and the solid electrolyte. The purpose is to provide.

Another object is to provide a manufacturing method capable of producing the negative electrode active material with high efficiency and low cost, and an electrode and lithium secondary battery containing the negative electrode active material.

However, the problem to be solved by the present invention is not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

According to one embodiment of the present invention,

Primary particles having a core portion containing metal particles and a shell portion containing amorphous carbon; and

an ion conductive material surrounding a plurality of the primary particles;

A negative electrode active material for a lithium secondary battery is provided, which includes secondary particles formed by including.

According to one embodiment of the present invention,

A step (S1) of mixing metal particles, solvent, and organic fatty acids, pulverizing them, and then drying them to produce metal precursor powder;

Mixing and stirring the metal precursor powder with tetrahydrofuran (THF) and an amorphous carbon precursor, drying and heat treating to form a silicon-carbon composite powder (S2);

Step (S3) of mixing lithium sulfide (Li ₂ S), phosphorus pentasulfide (P ₂ S ₅ ), and THF solvent and drying them to obtain LPS powder; and

Dispersing the silicon-carbon composite powder and LPS powder in a THF solvent, followed by spray drying and heat treatment (S4);

A method for producing a negative electrode active material is provided, including.

According to one embodiment of the present invention,

An electrode containing a negative electrode active material according to an embodiment of the present invention is provided.

According to one embodiment of the present invention,

In a lithium secondary battery including a negative electrode, a positive electrode, and an electrolyte,

A lithium secondary battery is provided, wherein the negative electrode includes a negative electrode active material according to an embodiment of the present invention.

The anode active material according to an embodiment of the present invention is composed of secondary particles composed of primary particles surrounded by silicon nanoparticles with amorphous carbon, and a high ionic conductivity material that uniformly surrounds the inside and outside of the secondary particles. , enabling a stable electrochemical reaction even during charging and discharging, enabling stable lifespan characteristics and excellent rapid charging and discharging characteristics.

The effects of the present invention are not limited to the effects described above, but should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a schematic diagram of a negative electrode active material according to an embodiment of the present invention.
Figure 2 is a graph showing the results of full cell life characteristics of manufacturing examples conducted in the present invention.
Figure 3 is a graph showing the impedance measurement results (ion conductivity measurement results) in the half cells of the manufacturing examples performed in the present invention.

Hereinafter, embodiments will be described in detail with reference to the attached drawings. However, various changes can be made to the embodiments, so the scope of the patent application is not limited or limited by these embodiments. It should be understood that all changes, equivalents, or substitutes for the embodiments are included in the scope of rights.

The terms used in the examples are for descriptive purposes only and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the embodiments belong. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless explicitly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

In addition, when describing with reference to the accompanying drawings, identical components will be assigned the same reference numerals regardless of the reference numerals, and overlapping descriptions thereof will be omitted. In describing the embodiments, if it is determined that detailed descriptions of related known technologies may unnecessarily obscure the gist of the embodiments, the detailed descriptions are omitted.

According to one aspect of the present invention,

Primary particles having a core portion containing metal particles and a shell portion containing amorphous carbon; and

an ion conductive material surrounding a plurality of the primary particles;

It provides a negative electrode active material for a lithium secondary battery, which includes secondary particles formed by including.

Among the primary particles of the negative electrode active material, the metal particles included in the core portion may include one or more selected from the group consisting of Si, Al, Zn, Ca, Mg, Fe, Mn, Co, Ni, and Ge, and the negative electrode In terms of improving the energy density and maximum capacity of the active material, silicon (Si) particles are preferred.

In addition, in order to suppress the volume change of the silicon, etc., it may be more preferable to use silicon-containing nanoparticles with a size of 1000 nm or less, and the silicon-containing nanoparticles are specifically silicon nanoparticles, silicon oxide nanoparticles, and silicon carbide. It may include one or more of nanoparticles and silicon alloy nanoparticles. Among them, the most preferred form may be one containing silicon nanoparticles.

In addition, according to an embodiment of the present invention, the outer surface of the core portion of the primary particle, such as a silicon-containing nanoparticle, may include a shell portion homogeneously wrapped with a material such as amorphous carbon.

By including this shell layer, the metal particles inside the core can have a configuration that does not directly contact the external ion conductive material, and the shell layer of the amorphous carbon forms an interface with the ion conductive material on the surface of the primary particle. By preventing alloying reactions between different elements at the interface, an electrochemically stable interface is formed. This enables a stable electrochemical reaction even during charging and discharging, ultimately contributing to stable battery life characteristics and excellent rapid charging and discharging characteristics.

On the other hand, when metal particles such as silicon and the ion conductive material come into direct contact, the problem of silicon elution may occur, and in addition, an alloy may be formed between silicon and the ion conductive material.

Meanwhile, the types of amorphous carbon are not greatly limited, but include sucrose, phenol resin, naphthalene resin, polyvinyl alcohol resin, and furfuryl alcohol resin. , furan resin, cellulose resin, styrene resin, polyimide resin, epoxy resin or vinyl chloride resin, coal-based pitch, petroleum-based pitch, polyvinyl chloride. , mesophase pitch, tar, block-copolymer, polyol, and low molecular weight heavy oil. More specifically, it may be formed from coal-based pitch, petroleum-based pitch, and acrylic resin. It may apply.

The shell portion may additionally include crystalline carbon as well as amorphous carbon of the series listed above.

In addition, the average particle size of the silicon-containing nanoparticles may be 50 nm to 1000 nm based on D ₅₀ , and preferably 80 nm to 500 nm.

If the average particle size (D ₅₀ ) of the silicon-containing nanoparticles exceeds the above range, the effect of suppressing volume change may decrease, resulting in a reduced battery life, and the average particle size (D ₅₀ ) may be less than the above lower limit. If it is less than that, manufacturing costs may increase and battery capacity and efficiency may decrease.

Additionally, the thickness of the shell layer containing the amorphous carbon may range from 50 nm to 1 μm.

Meanwhile, as described above, the negative electrode active material according to an embodiment of the present invention has a structure in which an ion conductive material is located outside of primary particles having a core-shell structure, thereby forming secondary particles. It represents.

The ion conductive material may be, specifically, a sulfide-based compound formed from lithium sulfide (Li ₂ S), phosphorus pentasulfide (P ₂ S ₅ ), and lithium halogen compound (LiX). there is.

Meanwhile, among the lithium halogen compounds, the halogen compound (X) may be one or more selected from the group consisting of chlorine (Cl), bromine (Br), and iodine (I). Through this, it is possible to secure electrochemical interface stability and lower the ion activation energy between the negative electrode active material and the electrolyte.

Meanwhile, the porosity of the secondary particles of the negative electrode active material according to an embodiment of the present invention may be 10% to 50%, and the average particle size of the secondary particles may be 3㎛ to 10㎛ based on D ₅₀ , more preferably Typically, it may be 5㎛ to 8㎛.

If the porosity is less than 10%, the expansion of the silicon particles may cause destruction of the composite, causing deterioration of lifespan characteristics, and if the porosity exceeds 50%, a decrease in initial efficiency and deterioration of lifespan characteristics may occur. It can cause it.

If the average particle size (D ₅₀ ) of the secondary particles is less than 3㎛, there may be a problem of reduced dispersibility in the electrode manufacturing process due to fine powder, and if it exceeds 10㎛, volume expansion of the secondary particles This may cause problems with lifespan and safety due to worsening electrode expansion.

According to one aspect of the present invention,

A step (S1) of mixing metal particles, solvent, and organic fatty acids, pulverizing them, and then drying them to produce metal precursor powder;

Mixing and stirring the metal precursor powder with tetrahydrofuran (THF) and an amorphous carbon precursor, drying and heat treating to form a silicon-carbon composite powder (S2);

Step (S3) of mixing lithium sulfide (Li ₂ S), phosphorus pentasulfide (P ₂ S ₅ ), and THF solvent and drying them to obtain LPS powder; and

Dispersing the silicon-carbon composite powder and LPS powder in a THF solvent, followed by spray drying and heat treatment (S4);

It provides a method for manufacturing a negative electrode active material, including.

The metal particles may correspond to one or more silicon-containing nanoparticles selected from the group consisting of silicon nanoparticles, silicon oxide nanoparticles, silicon carbide nanoparticles, and silicon alloy nanoparticles, as described above, and the solvent used in step S1 includes one or more selected from the group consisting of methanol, ethanol, propanol, and butanol, and is preferably isopropyl alcohol (IPA).

Meanwhile, the organic fatty acid is used to improve dispersion stability in the process and ensure chemical stability of the silicone precursor. Specific types include lauric acid, myristic acid, palmitic acid, stearic acid, and arachidic acid. there is.

Furthermore, the amorphous carbon can be considered to be substantially the same as the type of amorphous carbon described above, and the heat treatment in step S4 is performed at a temperature of about 300 to 500°C and an inert gas (e.g., Ar) atmosphere. The heat treatment may be carried out while raising the temperature at a rate of about 5°C/min for 2 to 4 hours, but is not limited thereto.

Meanwhile, according to one aspect of the present invention,

An electrode containing a negative electrode active material according to an embodiment of the present invention is provided,

In addition, a lithium secondary battery including a negative electrode, a positive electrode, and an electrolyte according to an embodiment of the present invention can also be provided.

In addition to the negative electrode active material described above, the negative electrode (electrode) may additionally include a negative electrode active material commonly used as a negative electrode active material for lithium batteries in the art. Materials of the commonly used anode active material may include, for example, one or more selected from the group consisting of lithium metal, metal alloyable with lithium, transition metal oxide, non-transition metal oxide, and carbon-based material.

In addition, the positive electrode may include a positive electrode active material, and the type of the positive electrode active material may be a lithium-containing metal oxide, and any type commonly used in the technical field can be applied to the lithium secondary battery of the present invention. .

Furthermore, the electrolyte may include a lithium salt-containing non-aqueous electrolyte, and specifically, a non-aqueous electrolyte solution, a solid electrolyte, an inorganic solid electrolyte, etc. may be used, and may preferably correspond to a solid electrolyte.

In addition, a separator such as glass fiber, polyester, Teflon, polyethylene, polypropylene, or polytetrafluoroethylene (PTFE) may be additionally disposed between the positive and negative electrodes and included in the lithium secondary battery.

Hereinafter, the configuration of the present invention and its effects will be described in more detail through examples and comparative examples. However, these examples are for illustrating the present invention in more detail, and the scope of the present invention is not limited to these examples.

- Example

(1) Manufacturing of negative electrode active material

a) Example 1

Silicone (D ₅₀ = 10㎛), isopropyl alcohol (IPA), and organic fatty acid were mixed in weight parts of 5:93:2, respectively, and the silicone was pulverized to a particle size of 158nm. The solute was obtained from the solution through a vacuum filter and then freeze-dried to prepare silicon particle powder composed of agglomerated silicon nanoparticles.

Afterwards, 2 g of petroleum pitch was added to 200 ml of tetrahydrofuran (THF) solvent and dispersed ultrasonically for 1 hour. 10 g of the silicon precursor powder was mixed, dispersed ultrasonically for 1 hour, and stirred at 75° C. overnight. The mixed solution was vacuum-dried in an oven at 90°C to remove the solvent, and then heat-treated in an inert atmosphere at 950°C to prepare silicon/carbon composite powder.

Afterwards, 10 g of raw material was prepared by mixing Li ₂ S and P ₂ S ₅ at a molar ratio of 7:3, 30 ml of THF solvent was added, wet ball milling was performed, and the solvent was dried at 55°C for more than 8 hours. After removal, LPS powder (Li ₇ P ₃ S ₁₁ ) was obtained. 2 g of the LPS powder was added to 400 ml of THF solvent and ultrasonic dispersion was performed for 1 hour. 4 g of silicon/carbon composite powder was added to the THF solution, and then ultrasonic dispersion was performed for 1 hour. The mixed solution was spray-dried in an inert atmosphere and then heat-treated at 400°C in an argon (Ar) atmosphere for 3 hours (temperature rise: 5°C/min) to obtain the final powder.

b) Example 2

A negative electrode active material was manufactured in the same manner as in Example 1 except that the silicon particle size was pulverized to 108 nm.

c) Example 3

A negative electrode active material was manufactured in the same manner as in Example 1 except that the silicon particle size was pulverized to 301 nm.

d) Example 4

A negative electrode active material was prepared in the same manner as in Example 1 except that the mixing ratio of LPS and silicon/carbon composite powder was set to 1:1.

e) Example 5

A negative electrode active material was prepared in the same manner as in Example 1 except that the mixing ratio of LPS and silicon/carbon composite powder was set to 2:1.

f) Comparative Example 1 (Manufacture of negative electrode active material composed of pure silicon primary particles)

Silicone (D ₅₀ = 10㎛), IPA, and organic fatty acid were mixed in weight parts of 5:93:2, respectively, and the silicone was pulverized to a particle size of 158nm. The solute was obtained from the solution through a vacuum filter and then freeze-dried to prepare silicon particle powder composed of agglomerated silicon nanoparticles.

Afterwards, 2 g of LPS powder was added to 400 ml of THF solvent and ultrasonic dispersion was performed for 1 hour. 4 g of silicon particle powder was added to the THF solution, and then ultrasonic dispersion was performed for 1 hour. The mixed solution was spray-dried in an inert atmosphere and then heat-treated at 400°C in an argon (Ar) atmosphere for 3 hours (temperature rise: 5°C/min) to obtain the final powder.

g) Comparative Example 2 (Preparation of negative electrode active material without ion conductive material)

Silicone (D ₅₀ = 10㎛), IPA, and organic fatty acid were mixed in weight parts of 5:93:2, respectively, and the silicone was pulverized to a particle size of 158nm. The solution was dried with a spray dryer to prepare a silicon precursor powder composed of agglomerated silicon nanoparticles with a D50 = 6㎛.

Afterwards, 2 g of petroleum pitch was added to 200 ml of THF solvent and ultrasonic dispersion was performed for 1 hour, and 10 g of the silicon precursor powder was mixed, followed by ultrasonic dispersion for 1 hour and stirring at 75°C overnight. The mixed solution was vacuum-dried in an oven at 90°C to remove the solvent, and then heat-treated in an inert atmosphere at 950°C to finally obtain a silicon/carbon composite powder.

h) Comparative Example 3 (Manufacture of negative electrode active material adding carbon nanotubes (CNT))

Silicone (D ₅₀ = 10㎛), isopropyl alcohol (IPA), and organic fatty acid were mixed in weight parts of 5:93:2, respectively, and the silicone was pulverized to a particle size of 158nm. CNTs were added to the solution in an amount of 2% by weight relative to silicon and stirred for 4 hours, and the solution was dried with a spray dryer to prepare silicon precursor powder with D ₅₀ = 6㎛. The subsequent process was carried out in the same manner as in Example 1, and the final powder was obtained.

(2) Manufacturing of coin cells

a) Fabrication of coin half shell

The negative electrode active material, conductive material (Super P), binder (PVDF), and solid electrolyte prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were uniformly mixed at a weight ratio of 90:2:4:4 to prepare a negative electrode slurry. Ready. Afterwards, the negative electrode slurry was coated on a copper thin film current collector with a thickness of 10㎛, and the coated electrode was dried at 120°C for 30 minutes and then pressed to produce a negative electrode.

The solid electrolyte was manufactured in the form of a circular pellet with a diameter of 16 mm by pressing LPS powder at 250 MPa for 40 minutes. A cell was manufactured by attaching Li foil to the solid electrolyte pellet and then attaching a cathode to the other side, and sealing/pressurizing it. A half cell was manufactured.

b) Fabrication of coin pool cell

Using the same cathode and solid electrolyte used in the coin half cell above, the anode was prepared as follows:

As a positive electrode active material, a positive electrode slurry was prepared by mixing LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , a conductive material, a binder (PVDF), and a solid electrolyte at a weight ratio of 92:3:3:2, and then the positive electrode slurry was mixed with a thickness of 12㎛. It was coated on an aluminum foil current collector, and the coated electrode plate was dried at 120°C for 30 minutes and pressed to produce a positive electrode.

A full cell was manufactured in the same manner as the half cell, using the above-prepared positive electrode instead of lithium metal as the counter electrode.

(3) Physical property evaluation method (Table 1)

a) Particle size measurement

The average particle size of the silicon particles and precursor was measured using a particle size meter (Mastersizer3000, Malvern Panalytical) using an organic solution in which the anode active material was dispersed.

b) Specific surface area measurement

The specific surface area of the sample was measured using TriStar Ⅱ 3020 equipment from Micromeritics, and was measured through the amount of nitrogen gas adsorption according to relative pressure changes at liquid nitrogen temperature (77K).

c) Measurement of powder electrical conductivity

The powder electrical conductivity of the negative electrode active materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3 was measured.

In this measurement method, the powder was pelletized and the electrical conductivity of the powder was measured using a 4-probe measurement method. After charging 500 mg of each negative active material powder into the powder resistance measurement container, a potential difference of 1 V was measured by 15% to measure DC resistance. It was applied for a minute, and the changing current was measured to calculate the DC resistance.

d) Measurement of powder ionic conductivity

The sample to be measured was charged into the electrochemical cell of the compression chamber and pressure was applied. The pellet produced at this time has a diameter of 13pi and a thickness of 90㎛.

Impedance measurement was performed to measure ionic conductivity, at room temperature (25°C) under conditions of an excitation amplitude of 5 to 10 mV and a frequency of 1 MHz to 1 Hz. The results are shown in Figure 3.

In addition, the data results summarizing the experiments of Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 1 below.

silicone size
(D50=㎚) secondary particle size
(D50=㎛) specific surface area
(m ² g ^-One ) Ion conductivity
(S cm ^-One ) electrical conductivity
(S cm ^-One ) Example 1 158 8.8 23.381 1.81×10 ^-5 2.9×10 ^-2 Example 2 108 8.3 21.987 7.96×10 ^-7 9.0×10 ^-3 Example 3 301 8.6 15.315 2.80×10 ^-5 4.2×10 ^-2 Example 4 158 7.9 34.821 9.17×10 ^-6 3.7×10 ^-2 Example 5 158 8.4 18.611 6.33×10 ^-5 7.9×10 ^-3 Comparative Example 1 158 7.7 63.106 3.86×10 ^-6 8.5×10 ^-4 Comparative Example 2 158 8.0 34.719 6.27×10 ^-9 9.5 Comparative Example 3 158 8.3 41.590 9.89×10 ^-7 1.4×10 ^-1

(4) Electrochemical evaluation method (Table 2)

Coin full cells were used to evaluate lifespan characteristics and high rate characteristics, and coin half cells were used to evaluate other battery characteristics.

a) Coin Half Cell

Coin half cells manufactured using the negative electrode active materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3 according to the present invention were operated at a current of 0.1 C at 25°C and a voltage of 0.01 V (vs. Li). It was charged at a constant current until this point, and while maintaining 0.01V, it was charged at a constant voltage until the current reached 0.05C. After the fully charged cell was rested for 10 minutes, it was discharged at a constant current of 0.1C until the voltage reached 1.5V (vs. Li) (performed twice, initial formation).

Meanwhile, “C” refers to the discharge rate of the cell, which is a value obtained by dividing the total capacity of the cell by the total discharge time.

The initial charge capacity and initial discharge capacity are the charge and discharge capacities in the first cycle, which were calculated from the following equation.

Initial efficiency [%] = (1st cycle discharge capacity/1st cycle charge capacity) × 100

b) Coin full cell

Coin full cells manufactured using the negative electrode active materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were charged at a constant current of 0.1C rate at 25°C until the voltage reached 4.2V, respectively. was charged at a constant voltage until the current reached 0.05C. After the fully charged cell was rested for 10 minutes, it was discharged at a constant current of 0.1C until the voltage reached 2.7V (performed twice, initial formation).

Afterwards, the cell was charged at a constant current of 1.0C at 25°C until the voltage reached 4.2V, and then charged at a constant voltage while maintaining 4.2V until the current reached 0.05C. After the fully charged coin cell was left to rest for 10 minutes, the discharging cycle was repeated with a constant current of 1.0C until the voltage reached 2.7V (1st to 50th cycles).

The lifespan characteristics were calculated from the following equation, and the results are shown in Table 2 and Figure 2.

Life characteristics [%] = (300th cycle discharge capacity/1st cycle discharge capacity) × 100

In addition, the data results summarizing the electrochemical evaluation experiments of Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 2 below.

Initial charging capacity
(mAh g-1) Initial discharge capacity
(mAh g-1) Initial efficiency (%) Life characteristics
(%@50th) Coin Half Cell coin full cell Example 1 1613.5 1402.4 86.9 87.1 Example 2 1649.5 1380.6 83.7 89.8 Example 3 1685.2 1479.6 87.8 83.1 Example 4 1629.6 1411.2 86.6 82.9 Example 5 1613.3 1398.7 86.7 85.6 Comparative Example 1 1639.0 1312.8 80.1 55.1 Comparative Example 2 1636.3 1402.3 85.7 47.9 Comparative Example 3 1455.8 1198.1 82.3 61.2

Through this, it was confirmed that Examples 1 to 5 containing the negative electrode active material according to an embodiment of the present invention had significantly superior lifespan characteristics and relatively good initial efficiency compared to Comparative Examples 1 to 3. You can.

As described above, although the embodiments have been described with limited drawings, those skilled in the art can apply various technical modifications and variations based on the above. For example, even if the described techniques are performed in a different order than the described method, and/or the described components are combined or combined in a different form than the described method, or are replaced or substituted by other components or equivalents. Adequate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents of the claims also fall within the scope of the following claims.

1: solid electrolyte
2: Silicon nanoparticles
3: Amorphous carbon

Claims (16)

Primary particles having a core portion containing metal particles and a shell portion containing amorphous carbon; and
an ion conductive material surrounding a plurality of the primary particles;
A negative electrode active material for a lithium secondary battery comprising secondary particles formed including. According to paragraph 1,
A negative active material for a lithium secondary battery, wherein the metal particles include one or more selected from the group consisting of Si, Al, Zn, Ca, Mg, Fe, Mn, Co, Ni, and Ge. According to paragraph 1,
A negative electrode active material, wherein the metal particles are one or more silicon-containing nanoparticles selected from the group consisting of silicon nanoparticles, silicon oxide nanoparticles, silicon carbide nanoparticles, and silicon alloy nanoparticles. According to paragraph 1,
A negative electrode active material, characterized in that the metal particles do not directly contact the ion conductive material. According to paragraph 1,
The ion conductive material is a sulfide-based compound formed from lithium sulfide (Li ₂ S), phosphorus pentasulfide (P ₂ S ₅ ), and lithium halogen compound (LiX),
Among the lithium halogen compounds, the halogen compound (X) is at least one selected from the group consisting of chlorine (Cl), bromine (Br), and iodine (I). According to paragraph 1,
An anode active material for a lithium secondary battery, wherein the shell portion additionally includes crystalline carbon. According to paragraph 3,
The average particle size of the silicon-containing nanoparticles is 80 nm to 500 nm based on D ₅₀ ,
A negative electrode active material wherein the shell portion has a thickness of 50 nm to 1 μm. According to paragraph 1,
The average particle size of the secondary particles is 3㎛ to 10㎛ based on D ₅₀ , a negative electrode active material. According to paragraph 1,
A negative electrode active material wherein the secondary particles have a porosity of 10% to 50%. According to paragraph 1,
The amorphous carbon includes sucrose, phenol resin, naphthalene resin, polyvinyl alcohol resin, furfuryl alcohol resin, furan resin, and cellulose. Resin, styrene resin, polyimide resin, epoxy resin or vinyl chloride resin, coal-based pitch, petroleum-based pitch, polyvinyl chloride, mesophase pitch, tar, block copolymer ( A negative electrode active material formed from one or more selected from the group consisting of block-copolymer), polyol, and low molecular weight heavy oil. A step (S1) of mixing metal particles, solvent, and organic fatty acids, pulverizing them, and then drying them to produce metal precursor powder;
Mixing and stirring the metal precursor powder with tetrahydrofuran (THF) and an amorphous carbon precursor, drying and heat treating to form a silicon-carbon composite powder (S2);
Step (S3) of mixing lithium sulfide (Li ₂ S), phosphorus pentasulfide (P ₂ S ₅ ), and THF solvent and drying them to obtain LPS powder; and
Dispersing the silicon-carbon composite powder and LPS powder in a THF solvent, followed by spray drying and heat treatment (S4);
Method for producing a negative electrode active material, including. According to clause 11,
The metal particles are one or more silicon-containing nanoparticles selected from the group consisting of silicon nanoparticles, silicon oxide nanoparticles, silicon carbide nanoparticles, and silicon alloy nanoparticles,
The solvent in step S1 is a solvent containing at least one selected from the group consisting of methanol, ethanol, propanol, and butanol,
The organic fatty acid is one or more selected from the group consisting of lauric acid, myristic acid, palmitic acid, stearic acid, and arachidic acid. According to clause 11,
The amorphous carbon precursor includes sucrose, phenol resin, naphthalene resin, polyvinyl alcohol resin, furfuryl alcohol resin, furan resin, and cellulose. Resin, styrene resin, polyimide resin, epoxy resin or vinyl chloride resin, coal-based pitch, petroleum-based pitch, polyvinyl chloride, mesophase pitch, tar, block copolymer ( A method of producing a negative electrode active material comprising at least one selected from the group consisting of block-copolymer), polyol, and low molecular weight heavy oil. According to clause 11,
A method of producing a negative electrode active material, wherein the heat treatment is performed at a temperature of 700°C to 1100°C for about 5 minutes to 5 hours. An electrode comprising the negative electrode active material of any one of claims 1 to 10. In a lithium secondary battery including a negative electrode, a positive electrode, and an electrolyte,
A lithium secondary battery, wherein the negative electrode includes the negative electrode active material of any one of claims 1 to 10.