KR20230039947A - Method for manufacturing Si nanoparticle lithium negative plate coated with porous carbon - Google Patents

Abstract

The present invention relates to a manufacturing method of a Si nanoparticle lithium negative electrode plate surface-coated with porous carbon and, more specifically, to a manufacturing method of a Si nanoparticle lithium negative electrode plate surface-coated with porous carbon which applies an active material mixture including Si nanoparticle materials surface-coated with porous carbon onto a lithium negative electrode plate, thereby increasing high electrical conductivity and durability.

Description

Method for manufacturing Si nanoparticle lithium negative plate coated with porous carbon

The present invention relates to a method for manufacturing a lithium negative plate of Si nanoparticles coated with porous carbon, and more particularly, by applying an active material mixture including Si nanoparticles coated with porous carbon to a lithium negative plate, thereby improving high electrical conductivity and durability. It relates to a method for manufacturing a lithium negative electrode plate of Si nanoparticles coated with porous carbon that can be improved.

In order to improve the problem of low capacity (372mAh/g) of graphite, an anode active material for lithium secondary batteries, negative electrodes for lithium secondary batteries are being manufactured based on silicon, which is abundantly distributed on the earth and has a low price.

However, silicon as an anode active material for a lithium secondary battery has chronic problems such as reduced electrical conductivity, volume expansion, and destabilization of an electrode-electrolyte interface, and has become a major cause of reduced cycle performance of a lithium ion battery.

A lithium secondary battery is a battery that generates electrical energy by a change in chemical potential when lithium ions are intercalated/deintercalated in a positive electrode and a negative electrode.

Such a lithium secondary battery is manufactured by using a material capable of reversible intercalation/deintercalation of lithium ions as a positive electrode and a negative electrode active material, and filling an organic electrolyte or polymer electrolyte between the positive electrode and the negative electrode.

Lithium composite metal compounds are used as cathode active materials for lithium secondary batteries. For example, composite metal oxides such as LiCoO2, LiMn2O4, LiNiO2, LiNi1-xCoxO2 (0 < x < 1), and LiMnO2 are being studied.

As an anode active material of a lithium secondary battery, graphite capable of intercalation/deintercalation of lithium has been typically applied.

However, since the electrode using graphite has a low charge capacity of 365 mAh/g (theoretical value: 372 mAh/g), there is a limit to providing a lithium secondary battery exhibiting excellent capacity characteristics.

Accordingly, inorganic active materials such as silicon (Si), germanium (Ge), or antimony (Sb) have been studied.

Such an inorganic active material, in particular, a silicon-based negative electrode active material, may exhibit a very large lithium bond amount (theoretical maximum value: Li 4 4 Si), which is close to a theoretical capacity of about 4200 mAh/g.

However, the silicon-based negative electrode active material causes intercalation/deintercalation of lithium, that is, a large volume change during charging and discharging of the battery, so that the active material may be pulverized.

As a result, fragments of the anode active material may be electrically detached from the current collector, which may result in irreversible capacity loss under a long cycle.

Another disadvantage of the silicon-based negative electrode active material is low electrical conductivity.

Due to this, the silicon-based negative electrode active material has a problem in that the output characteristics are inferior to those of the conventional carbon negative electrode active material, and this problem must be solved in the development of next-generation lithium secondary batteries.

In order to solve this problem, the cycle characteristics and output characteristics of the silicon-based negative electrode active material were improved by introducing a composite of a carbon material with excellent electrical conductivity and excellent mechanical properties and a silicon-based negative electrode material or a carbon surface coating.

Republic of Korea Patent Publication No. 10-2011-0134793 discloses carbon-coated silicon nanoparticles and a manufacturing method thereof.

Specifically, the above published patent relates to carbon-coated nanoparticles synthesized through hydrofluoric acid solution immersion, chloroform solution immersion, and ultrasonic treatment, and a method for preparing the same.

However, when these carbon-coated silicon nanoparticles are used as an anode active material, capacity and output characteristics are insufficient.

Accordingly, the present inventors have completed the present invention to improve these shortcomings.

Republic of Korea Patent Publication No. 10-2011-0134793

Therefore, the present invention has been made to solve the above conventional problems,

An object of the present invention is to improve high electric conductivity and durability by applying an active material mixture including porous carbon-surface-coated Si nanoparticles to a lithium negative plate.

In order to achieve the object to be solved by the present invention, a method for manufacturing a Si nanoparticle lithium negative electrode plate surface-coated with porous carbon according to an embodiment of the present invention,

A silicon organic compound, oleylamine, and 1-octadecene are put into a reactor and ultrasonic dispersion is performed for 30 minutes to 1 hour to prepare a first mixture, and the prepared first mixture is stored in a separate container. A first ultrasonic dispersion step for storage (S100); and

Thereafter, the first mixture, graphite, oleylamine, and 1-octadecene are put into a reactor and ultrasonic dispersion is performed for 30 minutes to 1 hour to prepare a second mixture, A second ultrasonic dispersion step (S200) for storing the second mixture in a separate container; and

After introducing the second mixture into the reactor, a thermal decomposition reaction step (S300) for performing 1 hour at 120 ° C. to remove moisture in an argon atmosphere and stirring at 300 ° C. for 2 hours for a thermal decomposition reaction; and

After completing the thermal decomposition reaction in the reactor, cooling the mixed solution to 80 ° C., and then filtering and washing using hexane and ethanol (S400); and

After drying the filtered and washed mixed solution in a vacuum oven at 60 ° C., grinding the dried composite, and annealing at high temperature for 1 hour in an Ar atmosphere using a furnace to Si nanoparticles coated with porous carbon on the surface. Si@C nanoparticle completion step (S500) to complete the material; and

A high-temperature aging and drying step (S600) for applying the active material mixture containing the Si nanoparticle material on which the porous carbon is surface-coated to a lithium negative plate (Cu or Al substrate) and then vacuum-drying it at a temperature of 120 degrees; By doing so, the problem of the present invention is solved.

Through the method of manufacturing the Si nanoparticle lithium anode plate surface-coated with the porous carbon of the present invention,

By applying an active material mixture including Si nanoparticles coated with porous carbon on a lithium negative plate (Cu or Al substrate), high electrical conductivity and durability are improved.

1 is a process diagram of a method for manufacturing a lithium negative electrode plate with Si nanoparticles surface-coated with porous carbon according to an embodiment of the present invention.
2 is an exemplary view showing Si nanoparticles surface-coated with porous carbon prepared by a method for manufacturing a lithium negative electrode plate with surface-coated porous carbon Si nanoparticles according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Since the present invention can have various changes and various forms, specific embodiments will be illustrated in the drawings and described in detail in the text.

However, it should be understood that this is not intended to limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms.

These terms are only used for the purpose of distinguishing one component from another.

For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention.

Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this application, the terms "comprise" or "have" are intended to designate that the features, steps, functions, components, or combinations thereof described in the specification exist, but other features, steps, functions, or components Or it should be understood that it does not exclude in advance the possibility of existence or addition of those in combination.

Meanwhile, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs.

Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

A method for manufacturing a Si nanoparticle lithium negative electrode plate surface-coated with porous carbon according to an embodiment of the present invention,

A silicon organic compound, oleylamine, and 1-octadecene are put into a reactor and ultrasonic dispersion is performed for 30 minutes to 1 hour to prepare a first mixture, and the prepared first mixture is stored in a separate container. A first ultrasonic dispersion step for storage (S100); and

Thereafter, the first mixture, graphite, oleylamine, and 1-octadecene are put into a reactor and ultrasonic dispersion is performed for 30 minutes to 1 hour to prepare a second mixture, A second ultrasonic dispersion step (S200) for storing the second mixture in a separate container; and

After introducing the second mixture into the reactor, a thermal decomposition reaction step (S300) for performing 1 hour at 120 ° C. to remove moisture in an argon atmosphere and stirring at 300 ° C. for 2 hours for a thermal decomposition reaction; and

After completing the thermal decomposition reaction in the reactor, cooling the mixed solution to 80 ° C., and then filtering and washing using hexane and ethanol (S400); and

After drying the filtered and washed mixed solution in a vacuum oven at 60 ° C., grinding the dried composite, and annealing at high temperature for 1 hour in an Ar atmosphere using a furnace to Si nanoparticles coated with porous carbon on the surface. Si@C nanoparticle completion step (S500) to complete the material; and

A high-temperature aging and drying step (S600) for applying the active material mixture containing the Si nanoparticle material on which the porous carbon is surface-coated to a lithium negative plate (Cu or Al substrate) and then vacuum-drying it at a temperature of 120 degrees; It is characterized by doing.

Specifically, the present invention, a method for producing a Si nanoparticle lithium negative electrode plate surface-coated with porous carbon,

5 parts by weight of a silicon organic compound, 5 parts by weight of oleylamine (70%), and 150 parts by weight of 1-octadecene (90%) were added to a reactor and ultrasonic dispersion was performed for 30 minutes to 1 hour to obtain A first ultrasonic dispersion step (S100) for preparing a first mixture and storing the prepared first mixture in a separate container; and

Thereafter, the first mixture, 3 parts by weight of graphite, 5 parts by weight of oleylamine, and 150 parts by weight of 1-octadecene were put into a reactor and ultrasonic dispersion was performed for 30 minutes to 1 hour. A second ultrasonic dispersion step (S200) for preparing a second mixture and storing the prepared second mixture in a separate container; and

After introducing the second mixture into the reactor, a thermal decomposition reaction step (S300) for performing 1 hour at 120 ° C. to remove moisture in an argon atmosphere and stirring at 300 ° C. for 2 hours for a thermal decomposition reaction; and

After completing the thermal decomposition reaction in the reactor, the mixed solution is cooled to 80 ° C., and then a cooling filtration step (S400) for filtering and washing using hexane (95%) and ethanol (95%); and

After drying the filtered and washed mixed solution in a vacuum oven at 60 ° C, grinding the dried composite, and annealing within the range of 800 ° C to 850 ° C for 1 hour in an Ar atmosphere using a furnace to form a porous A Si@C nanoparticle completion step (S500) of completing a surface-coated Si nanoparticle material with carbon; and

A high-temperature aging and drying step (S600) for applying the active material mixture containing the Si nanoparticle material on which the porous carbon is surface-coated to a lithium negative plate (Cu or Al substrate) and then vacuum-drying it at a temperature of 120 degrees; It is characterized by doing.

At this time, the silicon organic compound,

It is characterized by using triethoxysilane as a precursor.

At this time, the surface-coated Si nanoparticle material of the porous carbon,

In the annealing process, Si and Carbon are ionized and the segregation energy difference between the elements occurs during growth into bulk particles, and carbon is eluted on the surface of the powder body.

At this time, by the above manufacturing method,

It is possible to provide a battery including a lithium negative electrode plate with Si nanoparticles coated on the surface of the manufactured porous carbon.

Hereinafter, a method for manufacturing a lithium negative electrode plate with porous carbon surface-coated Si nanoparticles according to the present invention will be described in detail through examples.

1 is a process diagram of a method for manufacturing a lithium negative electrode plate with Si nanoparticles surface-coated with porous carbon according to an embodiment of the present invention.

As shown in FIG. 1, the present invention, a method for manufacturing a Si nanoparticle lithium negative plate coated with porous carbon,

5 parts by weight of a silicon organic compound, 5 parts by weight of oleylamine (70%), and 150 parts by weight of 1-octadecene (90%) were added to a reactor and ultrasonic dispersion was performed for 30 minutes to 1 hour to obtain A first ultrasonic dispersion step (S100) for preparing a first mixture and storing the prepared first mixture in a separate container; and

Thereafter, the first mixture, 3 parts by weight of graphite, 5 parts by weight of oleylamine, and 150 parts by weight of 1-octadecene were put into a reactor and ultrasonic dispersion was performed for 30 minutes to 1 hour. A second ultrasonic dispersion step (S200) for preparing a second mixture and storing the prepared second mixture in a separate container; and

After introducing the second mixture into the reactor, a thermal decomposition reaction step (S300) for performing 1 hour at 120 ° C. to remove moisture in an argon atmosphere and stirring at 300 ° C. for 2 hours for a thermal decomposition reaction; and

After completing the thermal decomposition reaction in the reactor, the mixed solution is cooled to 80 ° C., and then a cooling filtration step (S400) for filtering and washing using hexane (95%) and ethanol (95%); and

After drying the filtered and washed mixed solution in a vacuum oven at 60 ° C, grinding the dried composite, and annealing within the range of 800 ° C to 850 ° C for 1 hour in an Ar atmosphere using a furnace to form a porous A Si@C nanoparticle completion step (S500) of completing a surface-coated Si nanoparticle material with carbon; and

A high-temperature aging and drying step (S600) for applying the active material mixture containing the Si nanoparticle material on which the porous carbon is surface-coated to a lithium negative plate (Cu or Al substrate) and then vacuum-drying it at a temperature of 120 degrees; It is characterized by doing.

The present invention goes through the above manufacturing process, and through this, an active material mixture including Si nanoparticles coated with porous carbon is applied to a lithium negative plate (Cu or Al substrate), thereby improving high electrical conductivity and durability. will be.

That is, it provides a lifespan improvement effect that can prevent performance degradation and ultimately improve the basic performance and charging efficiency of the lithium battery.

In order to provide the above function, a specific process will be described as follows.

In the first ultrasonic dispersion step (S100), a silicon organic compound, oleylamine, and 1-octadecene are placed in a reactor and ultrasonic dispersion is performed for 30 minutes to 1 hour to prepare a first mixture. and storing the prepared first mixture in a separate container.

Specifically, 5 parts by weight of a silicon organic compound, 5 parts by weight of oleylamine (70%), and 150 parts by weight of 1-octadecene (90%) were placed in a reactor and ultrasonicated for 30 minutes to 1 hour. Dispersion is performed to prepare a first mixture, and the prepared first mixture is stored in a separate container.

As described above, the reason for performing ultrasonic dispersion is to facilitate dissolution.

In the second ultrasonic dispersion step (S200), the first mixture, graphite, oleylamine, and 1-octadecene are put into a reactor and ultrasonic dispersion is performed for 30 minutes to 1 hour. This is a step of preparing a second mixture and storing the prepared second mixture in a separate container.

Specifically, the first mixture, 3 parts by weight of graphite, 5 parts by weight of oleylamine, and 150 parts by weight of 1-octadecene were placed in a reactor and ultrasonicated for 30 minutes to 1 hour. Dispersion is performed to prepare a second mixture, and the prepared second mixture is stored in a separate container.

Thereafter, the thermal decomposition reaction step (S300) is a step for performing 1 hour at 120 ° C. to remove moisture in an argon atmosphere after introducing the second mixture into the reactor, and stirring at 300 ° C. for 2 hours for the thermal decomposition reaction. am.

As described above, the reason for removing moisture in the argon atmosphere is to make the mixtures more homogeneous.

At this time, if it exceeds 1 hour, too much moisture evaporates and during the thermal decomposition reaction, a problem of carbonization may occur, so the above time must be observed.

Thereafter, the cooling filtration step (S400) is a step of completing the thermal decomposition reaction in the reactor, cooling the mixed solution to 80 ° C, and then performing filtration and washing using hexane (95%) and ethanol (95%). .

Thereafter, in the Si@C nanoparticle completion step (S500), the filtered and washed mixed solution is dried in a vacuum oven at 60 ° C, the dried composite is ground, and the dried composite is ground for 1 hour in an Ar atmosphere using a furnace. This is a step of completing the Si nanoparticle material coated with porous carbon through annealing in the range of 800 ° C to 850 ° C.

Thereafter, in the high-temperature aging and drying step (S600), the active material mixture containing the porous carbon-surface-coated Si nanoparticles is applied to a lithium negative plate (Cu or Al substrate), followed by vacuum drying at a temperature of 120 degrees. It is a step.

For example, it is vacuum dried for 2 hours at a temperature of 120 degrees, and since vacuum drying technology is a general technology, detailed description will be omitted.

In addition, an attempt was made to fabricate porous carbon-coated Si@C through an annealing process of the silicon organic compound described in the present invention.

The above silicon organic compound precursor used triethoxysilane (triethoxysilane, (C2H5O)3SiH), and oleylamine was used as a dispersant to prevent aggregation of nanomaterials generated during sintering, and 1 as a solvent -octadecene (1-octadecene) was used.

In addition, graphite (graphite, graphite) was added as a conductive agent and silicon nano oxide carrier to improve conductivity and disperse nano silicon.

As shown in FIG. 2, the main principle is to manufacture nano-silicon coated with porous carbon through annealing, which is one of the Botton Up methods of silicon organic oxide precursors. In the annealing process, Si and Carbon are ionized to form bulk particles. Due to the segregation energy difference between elements generated during growth, the carbon material is eluted on the surface of the powder body, and it is eluted on the surface according to the annealing temperature.

The porous pores and carbon material coating formed on the surface are used to buffer volume change and increase electrical conductivity, thereby providing stable cycle and high electrical conductivity.

On the other hand, according to an additional aspect, in the Si@C nanoparticle completion step (S500),

The high temperature annealing temperature is

It is characterized in that within the range of 800 ℃ ~ 850 ℃.

That is, the degree to which carbon black is pushed out to the surface varies depending on the temperature.

For example, since the carbon source melted inside at 600 ° C. is appropriately pushed out to the surface of the nanoparticles, a carbon shell with pores is formed.

However, when the temperature exceeds 850 ° C., for example, at 855 ° C., the nanoparticles come out too much, blocking pores and preventing ion transmission, resulting in poor basic performance.

That is, when the annealing temperature exceeds the temperature condition, the crystallinity of the carbon improves and the density increases and the pore size gradually decreases.

Therefore, high-temperature annealing is performed within the above temperature range.

As described above, in order to grasp the effect of the present invention, basic performance and life test were conducted with a battery having a conventional lithium negative plate and a battery including a lithium negative plate made of porous carbon coated with Si nanoparticles manufactured according to the present invention. did

In an embodiment of the present invention, a lithium secondary battery including a lithium negative electrode plate of Si nanoparticles coated with porous carbon was prepared and the electrochemical characteristics were analyzed.

In Comparative Example 1, a lithium secondary battery was manufactured using commercially available silicon-based particles (SiO, Sigma Aldrich).

In Comparative Example 2, a silicon-based negative electrode active material coated with carbon not doped with nitrogen obtained after mixing commercial silicon-based particles and sucrose and then undergoing a carbonization process was prepared, and a lithium secondary battery was manufactured using the same.

In the case of Comparative Example 2, after mixing 0.6 g of commercially available silicon-based particles with 7.0 g of sucrose, silicon-based particles including a carbon coating layer not doped with nitrogen were prepared by heat treatment at 1,000 ° C. for 1 hour in the presence of nitrogen gas.

At this time, with respect to the cell manufactured according to the above, electrochemical characteristics were analyzed through a galvanostatic method.

As a result of driving the initial charge and discharge under a constant current condition of 0.1 C (150 mA / g), the initial discharge capacities of Example, Comparative Example 1, and Comparative Example 2 were 1258, 1429, and 1495 mAh / g in order.

In addition, in the case of the initial charge and discharge efficiency, it was found that the case of the embodiment has the best efficiency at 51.0, 71.4, and 72.9%.

It is judged that, in the case of nitrogen-doped carbon according to the present invention, it has excellent discharge capacity and efficiency due to excellent electrical conductivity.

As a result of measuring the discharge capacity while increasing the current density from 0.2C to 2C, in the case of the example, it was shown that a large discharge capacity of 732.3 mAh/g was implemented under a high driving current condition of 2C (3000mA/g).

This is a high capacity value that is twice as high as the discharge capacity of currently commercialized graphite anodes.

In the case of the examples, it can be seen that the size of the semicircle, which means the interfacial resistance of the electrode, did not significantly increase after initial charge and discharge and after 200 cycles.

On the other hand, in the case of Comparative Example 2, the interfacial resistance value greatly increased after 200 cycles, and the interfacial resistance was greater than that of Example.

This is considered to be that the interface of the Si nanoparticle lithium negative plate coated with porous carbon according to the present invention is stabilized.

According to the present invention, the Si nanoparticle lithium negative plate coated with porous carbon may have excellent discharge capacity and improved output characteristics compared to particles manufactured with a general carbon coating.

In particular, an excellent discharge capacity of 732.3 mAh/g can be realized even under a high charge/discharge driving current condition of 2C-rate (3000 mA/g).

Through the above manufacturing method, the active material mixture including the Si nanoparticle material coated with porous carbon is applied to the lithium negative plate (Cu or Al substrate), thereby exhibiting an effect of improving high electrical conductivity and durability.

Those skilled in the art to which the present invention pertains as described above will understand that it can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, the embodiments described above are illustrative in all respects and should be understood as not being limiting.

S100: 1st ultrasonic dispersing step
S200: Second ultrasonic dispersing step
S300: thermal decomposition reaction step
S400: Cooling filtration step
S500: Si@C nanoparticle completion step
S600: high temperature aging and drying step

Claims (5)

In the method for manufacturing a lithium negative electrode plate with Si nanoparticles coated with porous carbon,
A silicon organic compound, oleylamine, and 1-octadecene are put into a reactor and ultrasonic dispersion is performed for 30 minutes to 1 hour to prepare a first mixture, and the prepared first mixture is stored in a separate container. A first ultrasonic dispersion step for storage (S100); and
Thereafter, the first mixture, graphite, oleylamine, and 1-octadecene are put into a reactor and ultrasonic dispersion is performed for 30 minutes to 1 hour to prepare a second mixture, A second ultrasonic dispersion step (S200) for storing the second mixture in a separate container; and
After introducing the second mixture into the reactor, a thermal decomposition reaction step (S300) for performing 1 hour at 120 ° C. to remove moisture in an argon atmosphere and stirring at 300 ° C. for 2 hours for a thermal decomposition reaction; and
After completing the thermal decomposition reaction in the reactor, cooling the mixed solution to 80 ° C., and then filtering and washing using hexane and ethanol (S400); and
After drying the filtered and washed mixed solution in a vacuum oven at 60 ° C., grinding the dried composite, and annealing at high temperature for 1 hour in an Ar atmosphere using a furnace to Si nanoparticles coated with porous carbon on the surface. Si@C nanoparticle completion step (S500) to complete the material; and
A high-temperature aging and drying step (S600) for applying the active material mixture containing the Si nanoparticle material on which the porous carbon is surface-coated to a lithium negative plate (Cu or Al substrate) and then vacuum-drying it at a temperature of 120 degrees; A method for producing a Si nanoparticle lithium negative electrode plate surface-coated with porous carbon, characterized in that for doing.
According to claim 1,
The silicon organic compound,
A method for producing a Si nanoparticle lithium negative electrode plate surface-coated with porous carbon, characterized by using triethoxysilane as a precursor.
According to claim 1,
In the Si@C nanoparticle completion step (S500),
The high temperature annealing temperature is
Method for producing a Si nanoparticle lithium negative electrode plate surface-coated with porous carbon, characterized in that within the range of 800 ℃ ~ 850 ℃.
According to claim 1,
The Si nanoparticle material on which the porous carbon is surface-coated,
In the annealing process, Si and Carbon are ionized to form bulk particles, and segregation energy differences between the elements occur during growth, so that carbon is eluted on the surface of the powder body. Method for producing Si nanoparticle lithium negative plate coated with porous carbon .
By the manufacturing method of claim 1,
A battery comprising a lithium negative electrode plate of Si nanoparticles coated with porous carbon.

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