KR20230124793A - Method for fabrication of metal-coated carbon composite material and anode for a solid state battery using the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a composite material having a carbon structure coated with metal nanoparticles and a negative electrode for an all-solid-state battery manufactured using the same. A first step of preparing a mixture by dispersing the nanoparticles in a solvent; A metal-containing precursor is added to the mixture so that the carbon nanoparticles are coated with the metal nanoparticles reduced from the metal-containing precursor, but the amount of the metal nanoparticles is 1 to 50% by weight based on 100% by weight of the carbon nanoparticles. A second step of adjusting the amount of the metal-containing precursor so as to be coated on the carbon nanoparticles is provided.

Description

Method for fabrication of metal-coated carbon composite material and anode for a solid state battery using the same}

The present invention relates to a method for manufacturing a composite material having a carbon structure coated with metal nanoparticles and an anode for an all-solid-state battery manufactured using the same, and more specifically, to a composite material by coating carbon nanoparticles with metal nanoparticles at a certain level. When used as an anode material for a secondary battery by the configuration, the size of the metal nanoparticles coated on the carbon nanoparticles is adjusted through temperature control or viscosity control of the mixture in which the carbon nanoparticles are dispersed, and the desired performance is achieved with the minimum content. It relates to a method for manufacturing a composite material having a carbon structure coated with metal nanoparticles, which can reduce costs while securing, and an anode for an all-solid-state battery manufactured using the same.

Secondary batteries that can be charged and discharged are used not only for small electronic devices such as mobile phones and laptop computers, but also for large vehicles such as hybrid vehicles and electric vehicles. Accordingly, higher stability and higher energy density are required.

Since most of the general secondary batteries are composed of liquid electrolyte-based cells, there is a problem in that there is a risk of safety accidents when the battery is damaged, such as expansion of the battery due to temperature change or leakage due to external shock. In order to improve these problems and increase safety, an all-solid-state battery using a solid electrolyte that can be manufactured in a safe and simple type of cell has recently been in the limelight.

Since all-solid-state batteries use a solid electrolyte, they are structurally hard and can maintain their shape even if the electrolyte is damaged, so they have the advantage of improving safety.

In manufacturing the negative electrode of such an all-solid-state battery, in the conventional case, lithium metal has been used as the negative electrode of the all-solid-state battery to improve energy density.

However, when lithium metal is used as an anode of an all-solid-state battery, there are problems in that coulombic efficiency (or charge/discharge efficiency) decreases and short circuit occurs due to the growth of dendrites. Efforts have been made to resolve it.

Dendrites are crystals that accumulate on the surface of lithium metal in the shape of branches and are known to hinder the movement of lithium ions, resulting in reduced charge and discharge efficiency and shortened lifespan of all-solid-state batteries.

As a conventional method for suppressing such dendrite, a method of suppressing dendrite growth by forming a protective layer on lithium metal or applying a Li-In alloy is known. Since it is necessary to use, there is a problem in the process, and there is a problem of shortening the life due to the volume expansion of the lithium metal during the charging and discharging process.

Accordingly, there has been a demand for an anode material capable of securing stability and having a high energy density without deterioration in charge/discharge efficiency without using lithium metal as an anode material.

Republic of Korea Patent Publication No. 10-2019-0041736 (2019.04.23.)

Accordingly, an object of the present invention is to provide a method for manufacturing a composite material having a carbon structure coated with metal nanoparticles capable of overcoming the above conventional problems and a negative electrode for an all-solid-state battery manufactured using the same.

Another object of the present invention is to manufacture a composite material having a carbon structure coated with metal nanoparticles capable of controlling the size or uniformity of the metal nanoparticles coated on the carbon nanoparticles through temperature control or viscosity control of a mixture in which the carbon nanoparticles are dispersed. It is to provide a method and a negative electrode for an all-solid-state battery manufactured using the same.

Another object of the present invention is a method for manufacturing a composite material having a carbon structure coated with metal nanoparticles capable of overcoming instability at the interface between an anode and an electrolyte, having a high energy density, and securing stability in an all-solid-state battery, and using the same It is to provide a negative electrode for an all-solid-state battery manufactured by.

Another object of the present invention is a method for manufacturing a carbon structured composite material coated with metal nanoparticles, which has high energy density and can secure stability without deterioration in charge/discharge efficiency without using lithium metal as an anode material. And to provide a negative electrode for an all-solid-state battery manufactured using the same.

According to the embodiment of the present invention for achieving some of the above technical problems, a method for producing a composite material having a carbon structure coated with metal nanoparticles according to the present invention comprises a first step of preparing a mixture by dispersing the carbon nanoparticles in a solvent. step; A metal-containing precursor is added to the mixture so that the carbon nanoparticles are coated with the metal nanoparticles reduced from the metal-containing precursor, but the amount of the metal nanoparticles is 1 to 50% by weight based on 100% by weight of the carbon nanoparticles. and a second step of adjusting the amount of the metal-containing precursor so as to be coated on the carbon nanoparticles, and the mixture satisfies the following equation representing a correlation between temperature (° C.) and viscosity (cP), The average size of the metal nanoparticles coated on the carbon nanoparticles in the second step is controlled by controlling the viscosity or temperature of the mixture.

By controlling the viscosity of the mixture by setting the temperature of the mixture to 20 to 40 ° C, the average size of the metal nanoparticles coated on the carbon nanoparticles in the second step can be adjusted to 1 to 100 nm. there is.

In the second step, the metal nanoparticles may be reduced from the metal-containing precursor to be coated on the carbon nanoparticles by using a Taylor flow method using a Kuett-Taylor reactor or an electron beam irradiation method using an electron beam.

In the second step, when the metal-containing precursor is added to the mixture, a reducing agent may be added together.

The reducing agent is sodium borohydride (NaBH ₄ ), hydrazine (N ₂ H ₄ ), ascorbic acid (C ₆ H ₈ O ₆ ), hydroquinone (C ₆ H ₆ O ₂ ), citric acid (C ₆ H ₈ O ₇ ) And it may be at least one selected from the group consisting of glucose (C ₆ H ₁₂ O ₆ ).

After the second step, a step of separating the carbon nanoparticles coated with the metal nanoparticles from the mixture, drying and firing the mixture may be further included.

The firing may be performed at 300 ° C to 800 ° C for 1 hour to 24 hours in an inert or reducing gas atmosphere.

The carbon nanoparticles may be composed of at least one selected from carbon black, graphene, activated carbon, carbon fiber, acetylene black, ketjen black, and carbon nanotubes.

The carbon nanoparticles may have an average size of 1 to 500 nm.

The solvent may be any one selected from distilled water, methanol, ethanol, propanol, butanol, acetone, glycerol, and tetrahydrofuran, or a mixture of at least two of them.

The metal-containing precursor is a water-soluble precursor, and at least one is selected from oxide salts, oxyhydroxide salts, chloride salts, carbonates, acetates, citrates, nitrosilnitrates, nitrates, hydroxides, oxalates, carboxylates, and sulfates of metals. , At least one of an alkoxy precursor and an ammonium precursor containing a hydrocarbon may be selected as a lipophilic precursor.

The metal contained in the metal-containing precursor is silver (Ag), platinum (Pt), palladium (Pd), gold (Au), iridium (Ir), osmium (Os), rhodium (Rh) and ruthenium (Ru). It may be at least one selected metal.

The metal-containing precursor may be a silver precursor containing silver (Ag).

The composite material having a carbon structure coated with the metal nanoparticles may form an anode for an all-solid-state battery.

A negative electrode for an all-solid-state battery according to another embodiment of the present invention for achieving some of the above technical problems includes a negative electrode current collector; An anode active material layer formed on the anode current collector is provided, and the anode active material layer includes a composite material having a carbon structure coated with metal nanoparticles manufactured according to any one of claims 1 to 13.

The negative electrode active material layer may be formed by depositing a composite material having a carbon structure coated with the metal nanoparticles on the surface of the negative electrode current collector to a predetermined thickness.

The negative electrode active material layer may be formed in a layered structure on the surface of the negative electrode current collector by compressing powder or slurry of a composite material having a carbon structure coated with the metal nanoparticles.

The negative electrode active material layer may have a structure in which a solid electrolyte and a composite material having a carbon structure coated with the metal nanoparticles are dispersed.

The solid electrolyte may include at least one of an organic solid electrolyte, an inorganic solid electrolyte, and a sulfide-based solid electrolyte.

The solid electrolyte may be a sulfide-based solid electrolyte.

According to the present invention, the size or uniformity of the metal nanoparticles coated on the carbon nanoparticles can be adjusted by controlling the temperature or viscosity of the mixture in which the carbon nanoparticles are dispersed. There is an advantage in that it is possible to manufacture a negative electrode material for an all-solid-state battery by coating the carbon nanoparticles with the metal nanoparticles having an appropriate range.

In addition, it is possible to construct an anode for an all-solid-state battery using a composite material having a carbon structure coated with metal nanoparticles without using lithium metal as an anode material, and it is possible to reduce the nucleation energy of lithium and to generate lithium ion There is an advantage in suppressing dendrite generation by minimizing isolated lithium in the process of being electrodeposited and desorbed on the negative electrode current collector. In addition, by overcoming the instability at the interface between the cathode and the solid electrolyte, an all-solid-state battery having high energy density and securing stability is possible. In particular, since the instability of a sulfide-based all-solid-state battery mainly occurs at the interface between the positive electrode and the electrolyte and the interface between the negative electrode and the electrolyte, an all-solid-state battery that has high energy density and secures stability by overcoming the instability at the interface between the negative electrode and the electrolyte. becomes possible

1 is a process flow chart for manufacturing a composite material having a carbon structure coated with metal nanoparticles according to the present invention;
2 is a TEM (Transmission Electron Microscopy) photograph of carbon nanoparticles,
3 is a TEM photograph of a composite material including carbon nanoparticles coated with metal nanoparticles;
4 is a TEM photograph of a composite material having a carbon structure coated with metal nanoparticles prepared in Example 1;
5 is a TEM photograph of a composite material having a carbon structure coated with metal nanoparticles prepared in Example 2;
6 is a TEM photograph of a composite material having a carbon structure coated with metal nanoparticles prepared according to Comparative Example;
7 is a graph showing the particle distribution of metal nanoparticles coated in the composite materials of Example 1, Example 2, and Comparative Example;
8 is a schematic cross-sectional view of an all-solid-state battery according to the present invention;
9 is a graph showing the charge/discharge efficiency of an all-solid-state battery using a composite material having a carbon structure coated with metal nanoparticles as an anode material.

Hereinafter, preferred embodiments of the present invention will be described in detail without any intention other than to provide a thorough understanding of the present invention to those skilled in the art to which the present invention belongs.

1 is a process flow chart for manufacturing a composite material having a carbon structure coated with metal nanoparticles according to the present invention.

As shown in FIG. 1, the composite material having a carbon structure coated with metal nanoparticles according to the present invention is prepared through a mixture preparation step (S110), a coating step (S120), and a drying and firing step (S130).

The mixture preparation step (S110) is a step of preparing a mixture by dispersing carbon nanoparticles in a solvent.

As shown in the TEM (Transmission Electron Microscopy) photograph shown in FIG. 2, each of the carbon nanoparticles may have a spherical or elliptical structure, and may have an average diameter within a range of 1 to 500 nm. The carbon nanoparticles can be obtained from various commercial sources or prepared by methods well known to those skilled in the art.

Each of the carbon nanoparticles can be used without limitation as long as it has electrical conductivity and can be applied to an all-solid-state battery. For example, carbon black, graphene, activated carbon, carbon fiber, carbon powder, acetylene black, Ketjen black, and At least one of carbon nanotubes may be selected and used. Among these, carbon black may be advantageous in terms of cost reduction and process simplification.

Each of the carbon nanoparticles is a porous material and contains many pores, so that metal nanoparticles can be coated in the pores, so that the coated metal nanoparticles can be sufficiently supported, and there is no reactivity with the coated metal nanoparticles, and the carbon nanoparticles are not reactive to the temperature. It is desirable to select a material that is not sensitive to changes.

Since the carbon nanoparticles have many sites capable of bonding with lithium ions, when the composite material is used for a negative electrode of an all-solid-state battery, it can store lithium ions moved to the negative electrode by charging and maintain the potential of the battery. allows you to

The solvent may be used without limitation in capacity or type as long as the conditions are suitable for coating the metal nanoparticles on the carbon nanoparticles during the mixing process for the reaction. In addition, any solvent capable of mixing metal-containing precursors, reducing agents, and carbon nanoparticles, including silver precursors, may be used without limitation in capacity or type.

The solvent may be selected to uniformly mix the components contained in the mixture and to control the viscosity so that the carbon nanoparticles are uniformly dispersed. In addition, a solvent that can be well mixed with the metal-containing precursor introduced in the coating step (S120), which is a subsequent process, may be selected. For example, the solvent may be composed of any one selected from distilled water, methanol, ethanol, propanol, butanol, acetone, glycerol, and tetrahydrofuran, or a mixture of at least two of them. The solvent is preferably distilled water in consideration of the environmental aspect.

The coating step (S120) is a step of adding a metal-containing precursor to the mixture so that the carbon nanoparticles are coated with the reduced metal nanoparticles from the metal-containing precursor. At this time, in order to reduce the metal nanoparticles from the metal-containing precursor, a method well known to those skilled in the art, such as a Taylor flow method using a Kuett-Taylor reactor, an electron beam irradiation method using an electron beam, or a method using a simple mixing reaction, may be used. can

The Taylor flow method uses a Couette-Taylor reactor, and is a method of reducing time, high quality, and high productivity through continuous production, and the electron beam irradiation method irradiates electron beams so that silver nanoparticles are coated on carbon nanoparticles. In such a way, it is known that production of high purity and high quality materials is possible. The Taylor flow method and the electron beam irradiation method are well known to those skilled in the art, and the composite material can be produced by changing some process conditions and process sequence to these known manufacturing methods. .

The metal-containing precursor is a water-soluble precursor, and at least one is selected from oxide salts, oxyhydroxide salts, chloride salts, carbonates, acetates, citrates, nitrosilnitrates, nitrates, hydroxides, oxalates, carboxylates, and sulfates of metals. , At least one of an alkoxy precursor and an ammonium precursor containing a hydrocarbon may be selected as a lipophilic precursor. Preferably, the metal-containing precursor may be a silver precursor containing silver (Ag).

In addition, the metal contained in the metal-containing precursor is silver (Ag), platinum (Pt), palladium (Pd), gold (Au), iridium (Ir), osmium (Os), rhodium (Rh) and ruthenium (Ru ) It may be at least one metal selected from among.

When the metal-containing precursor is added to the mixture in the coating step (S120), a reducing agent may be added together.

In the case of reducing metal nanoparticles using an electron beam irradiation method in which electron beam irradiation is used, a separate reducing agent is not required, but a reducing agent may be added when using another method or to maximize the effect.

The reducing agent is an agent that reduces metal cations in a solution in which the metal-containing precursor is added to the mixture in which the carbon nanoparticles are dispersed are bound to metal nanoparticles by the electrostatic attraction of the oxygen-containing carbon nanoparticles. As, the ratio of the metal-containing precursor and the reducing agent may be determined according to a commonly known method without limitation depending on the type of reducing agent. The reducing agent is sodium borohydride (NaBH ₄ ), hydrazine (N ₂ H ₄ ), ascorbic acid (C ₆ H ₈ O ₆ ), hydroquinone (C ₆ H ₆ O ₂ ), citric acid (C ₆ H ₈ O ₇ ) And it may be at least one selected from the group consisting of glucose (C ₆ H ₁₂ O ₆ ).

In the present invention, when a metal-containing precursor is added to the mixture, the amount of metal nanoparticles coated on the carbon nanoparticles is 1 to 50% by weight with respect to 100% by weight of the carbon nanoparticles. You will control the dosage. Preferably, the amount of the metal-containing precursor is adjusted so that 1 to 25 wt% of the metal nanoparticles are coated on the carbon nanoparticles with respect to 100 wt% of the carbon nanoparticles.

When the amount of the metal-containing precursor is too small and the content of the metal nanoparticles coated on the carbon nanoparticles is less than 1% by weight, the activity of the reaction may decrease when used as an anode material for an all-solid-state battery. When the content of metal nanoparticles coated on the nanoparticles exceeds 50% by weight, the amount of metal coated on the carbon nanoparticles is too large, so that they are not completely coated on the carbon nanoparticles in the process of manufacturing a negative electrode of an all-solid-state battery. Some of the metal nanoparticles may be leached, and at the same time, the interaction between the carbon nanoparticles and the metal nanoparticles may be weakened, causing a problem of sintering between the metal nanoparticles during manufacturing and reaction processes.

The average size (average diameter) of the metal nanoparticles coated on the carbon nanoparticles may range from 1 to 100 nm, and the average size should be smaller than that of the carbon nanoparticles. In addition, when the metal nanoparticles are coated on the carbon nanoparticles, it is necessary to have a small particle size and be uniformly synthesized in order to secure uniformity. In this case, the average size (average diameter) set to have a size advantageous in the manufacturing process and advantageous in securing uniformity of coating is in the range of 1 to 100 nm. That is, when the composite material is used for the negative electrode of an all-solid-state battery, the metal nanoparticle may have an alloy reaction with lithium in the charging step and a uniform lithium ion (Li+) flux and electric field. As the optimal average particle size (diameter) in the range, 1 to 100 nm was selected.

The metal nanoparticles are intended to have a low atomic mismatch and high binding energy with copper (Cu), which is mainly used as an anode current collector, when the composite material of the present invention is used for an anode of an all-solid-state battery. . In the conventional case, when lithium is used for an anode, an atomic mismatch occurs at an interface with copper used as an anode current collector. Accordingly, there is a problem of causing a low binding energy (approximately ~ 1.4 eV). However, metal nanoparticles (eg, silver nanoparticles) have an atomic diameter of 0.172 nm, a lower atomic mismatch compared to lithium and copper, and a high binding energy (approximately ~2.3 eV). There are advantages. In addition, the metal nanoparticles may have an effect of reducing resistance in seed formation with respect to lithium ions moving to the negative electrode during charging of the all-solid-state battery.

The reason why nano-sized particles such as the carbon nanoparticles and the metal nanoparticles are used in the manufacture of the composite material is that when the composite material is used as a negative electrode of an all-solid-state battery, when a micro-sized particle is used, in the case of a nano-sized There is a problem in that variation occurs in the distance between the positive electrode and the negative electrode because the expansion and contraction according to charge and discharge are greater. There is a problem in that a portion where the distance between the anode and the cathode is far apart is difficult to charge due to high overvoltage during charging, and a portion where the distance between the anode and cathode is close to each other is easy to charge due to a low overvoltage. That is, there is a problem that battery capacity may decrease each time a charge/discharge cycle is repeated due to the formation of a portion that is difficult to charge and a portion that is easy to charge. will manufacture

The TEM picture shown in FIG. 3 shows a composite material in which carbon nanoparticles with relatively large particles are coated with relatively fine metal nanoparticles (eg, silver nanoparticles) represented by small white dots. there is.

At this time, pores are formed between the carbon nanoparticles constituting the composite material, and the average size (diameter) of the pores is 15 to 15 so that the metal nanoparticles are uniformly coated in a state in which the carbon nanoparticles are uniformly dispersed. It can be made to be 20nm.

In addition, the metal nanoparticles may be coated on the carbon nanoparticles in a powder form or a slurry form.

On the other hand, in order for the metal nanoparticles to be small and uniform, that is, to maintain uniformity and cover the carbon nanoparticles with a relatively small average size within the range of 1 to 100 nm, the carbon nanoparticles must be uniformly dispersed in the mixture. need something

That is, the degree of dispersion of the carbon nanoparticles has a great influence on the physical properties of the metal nanoparticles coated on the carbon nanoparticles. When aggregates of carbon nanoparticles exist due to poor dispersion of the carbon nanoparticles, metal nanoparticles are not uniformly supported due to the existence of the agglomerates. Accordingly, in the present invention, by measuring the viscosity of the mixture, factors influencing the synthesis of the mixture in which carbon nanoparticles are dispersed and small and uniform metal nanoparticles using the mixture were examined.

Through a number of experiments for the preparation of the composite material of the present invention, in the case of the mixture, when the viscosity of the mixture, which can determine the degree of dispersion of the carbon nanoparticles, changes, the carbon nanoparticles in the coating step (S120). It was confirmed that the average size (or average diameter) and uniformity of the reduced metal nanoparticles to be coated on the field varied.

In addition, it was confirmed that the viscosity of the mixture was correlated with temperature, and that the viscosity of the mixture was controlled by a change (adjustment) of the temperature of the mixture as shown in the following equation. This is a product of the results of a number of experiments on mixtures of various compositions, and through this, it was confirmed that the mixture had a viscosity-temperature correlation such as the equation described later.

Calculating this mathematically, the mixture prepared by dispersing carbon nanoparticles in a solvent satisfies the following equation representing the correlation between temperature (℃) and viscosity (cP), and the viscosity (cP) of the mixture is It can be seen that control is possible by adjusting the temperature (° C.) of the mixture through the following equation.

The above formula can be applied at a low shear rate, which is to minimize the effect of viscous heating and the shear rate according to the composition of the mixture. In addition, the mixture applied to the present invention may be limited to a mixture to which the correlation according to the above formula is applied.

In addition, through a number of experiments and analyzes, when the mixture is in a specific viscosity range, the average size of the metal nanoparticles reduced to be coated on the carbon nanoparticles in the coating step (S120) is uniform at 1 to 100 nm. It was confirmed that it was formed. That is, it was confirmed that the metal nanoparticles coated on the carbon nanoparticles were small and uniform with an average size of 1 to 100 nm. The viscosity (cP) of the mixture can be controlled by adjusting the temperature (° C.) of the mixture as shown in the above equation.

Accordingly, it can be seen that the average size or uniformity of the metal nanoparticles coated on the carbon nanoparticles can be adjusted by controlling the viscosity or temperature of the mixture.

In particular, when the mixture is in a specific temperature range (for example, a range of 20 to 40° C.), the average size of the metal nanoparticles coated on the carbon nanoparticles in the coating step (S120) is as small as 1 to 100 nm. It was found to be uniform. This can be confirmed through Examples 1 and 2, and Comparative Examples to be described later.

The drying and firing step (S130) is a step of separating the carbon nanoparticles coated with metal nanoparticles from the mixture, washing with water, drying and firing.

First, in order to separate the carbon nanoparticles coated with the metal nanoparticles, the solvent is evaporated using a filter method or solid-liquid phase separation through a rotary evaporator, or a phase separation process is performed by a method well known to those skilled in the art. Through this, only carbon nanoparticles coated with metal nanoparticles are separated.

Thereafter, purification may be performed by washing and washing with distilled water, ethanol, acetone, etc. to remove unstable cations and anions that may remain in the carbon nanoparticles.

Then, drying may be performed at room temperature to 120 ° C. by a method well known to those skilled in the art, such as hot air, constant temperature and humidity, microwave, and vacuum.

Next, firing may be variously changed in consideration of the unique glass transition temperature according to the type of the carbon nanoparticles, but preferably, in order to prevent oxidation of the coated metal nanoparticles (for example, silver nanoparticles), inert or It is carried out in a reducing gas atmosphere and can be fired at 300 ℃ ~ 800 ℃ for 1 hour to 24 hours.

If the calcination temperature is too low, organic impurities reacted with the metal-containing precursor and the reducing agent may remain on the carbon nanoparticles coated with the metal nanoparticles, increasing side reactions. This is undesirable because the particle size may increase, thereby reducing the dispersibility or reducing the specific surface area of the carbon nanoparticles. Since rapid calcination temperature change may cause the structure of carbon nanoparticles to become unstable due to rapid evaporation or sintering of the solvent, it is preferable to prepare the carbon nanoparticles by gradually increasing the temperature to 10° C. or less per minute.

Through the above-described drying and firing step (S130), a composite material in which metal nanoparticles are coated with carbon nanoparticles, that is, a composite material having a carbon structure coated with metal nanoparticles is manufactured.

Hereinafter, manufacturing examples and comparative examples of the composite material will be described.

[Example 1]

3000 g of distilled water, 3000 g of glycerol, 1500 g of ethanol, and 750 g of tetrahydrofuran were mixed and dispersed while maintaining the mixture with 30 g of carbon black at a temperature of 23 to 28 ° C. for 30 minutes with uniform stirring. Next, 22.52 g of silver nitrate was put into a beaker to prepare a silver precursor solution so that 20% of the total weight of the carbon nanoparticles was coated with the silver nanoparticles. In the case of preparing a reducing agent solution, the molar ratio of silver (Ag) and hydrazine (N ₂ H ₄ ) was prepared to be 1:2. The reaction was carried out by injecting a certain amount of the three solvent mixtures, the silver nitrate solution, and the reducing agent solution into the inlet of the continuous reactor using a metering pump while sufficiently stirring to form a slurry. Thereafter, the carbon nanoparticles coated with the solvent and the silver nanoparticles were separated using a filter, and washed with distilled water and ethanol several times until impurities were removed. Thereafter, drying was performed at 80° C. for 24 hours in an air atmosphere oven and firing was performed to prepare a composite material having a carbon structure in which silver nanoparticles were uniformly supported.

FIG. 4 is a TEM photograph of a composite material having a carbon structure coated with metal nanoparticles prepared in Example 1. As shown in FIG. 4, silver nanoparticles, which are metal nanoparticles, are coated on the carbon nanoparticles. As the temperature of the mixture is controlled at a temperature of 23 to 28 ° C., and the viscosity of the mixture is controlled, it can be confirmed that the average size of the coated silver nanoparticles is adjusted to be small and uniform at 25 nm.

[Example 2]

3000 g of distilled water, 3000 g of glycerol, 1500 g of ethanol, and 750 g of tetrahydrofuran were mixed and dispersed while maintaining the mixture with 30 g of carbon black at a temperature of 32 to 38 ° C. for 30 minutes with uniform stirring. Next, to prepare a silver precursor solution, 22.52 g of silver nitrate was put in a beaker, and 20% of the total weight of the carbon nanoparticles was covered with silver nanoparticles. In the case of preparing a reducing agent solution, the molar ratio of silver (Ag) and hydrazine (N ₂ H ₄ ) was prepared to be 1:2. The reaction was carried out by injecting a certain amount of the three solvent mixtures, the silver nitrate solution, and the reducing agent solution into the inlet of the continuous reactor using a metering pump while sufficiently stirring to form a slurry. Thereafter, the carbon nanoparticles coated with the solvent and the silver nanoparticles were separated using a filter, and washed with distilled water and ethanol several times until impurities were removed. Thereafter, drying was performed at 80° C. for 24 hours in an air atmosphere oven and firing was performed to prepare a composite material having a carbon structure in which silver nanoparticles were uniformly supported.

FIG. 5 is a TEM photograph of a composite material having a carbon structure coated with metal nanoparticles prepared in Example 2. As shown in FIG. 5, silver nanoparticles, which are metal nanoparticles, are coated on the carbon nanoparticles. As the temperature of the mixture is controlled at a temperature of 32 to 38 ° C. to control the viscosity of the mixture, it can be confirmed that the average size of the coated silver nanoparticles is adjusted to be small and uniform at 39 nm.

[Comparative example]

3000 g of distilled water, 3000 g of glycerol, 1500 g of ethanol, and 750 g of tetrahydrofuran were mixed and dispersed while maintaining the mixture containing 30 g of carbon black at a temperature of 41 to 48 ° C. for 30 minutes with uniform stirring. Next, to prepare a silver precursor solution, 22.52 g of silver nitrate was put in a beaker, and 20% of the total weight of the carbon nanoparticles was covered with silver nanoparticles. In the case of preparing a reducing agent solution, the molar ratio of silver (Ag) and hydrazine (N ₂ H ₄ ) was prepared to be 1:2. The reaction was carried out by injecting a certain amount of the three solvent mixtures, the silver nitrate solution, and the reducing agent solution into the inlet of the continuous reactor using a metering pump while sufficiently stirring to form a slurry. Thereafter, the carbon nanoparticles coated with the solvent and the silver nanoparticles were separated using a filter, and washed with distilled water and ethanol several times until impurities were removed. Thereafter, drying was performed at 80° C. for 24 hours in an air atmosphere oven and firing was performed to prepare a composite material having a carbon structure in which silver nanoparticles were uniformly supported.

6 is a TEM photograph of a composite material having a carbon structure coated with metal nanoparticles prepared according to a comparative example. As shown in FIG. 6, silver nanoparticles, which are metal nanoparticles, are coated with carbon nanoparticles As the viscosity of the mixture is controlled by controlling the temperature of the mixture at a temperature of 41 to 48 ° C, it can be confirmed that the average size of the coated silver nanoparticles is 105 nm, which is relatively large and non-uniform.

7 is a graph showing the particle distribution of metal nanoparticles coated in the composite materials of Example 1, Example 2, and Comparative Example.

As shown in FIG. 7, in the case of Example 1 in which the viscosity of the mixture is controlled by setting the temperature of the mixture to 23 to 28 ° C, the produced metal nanoparticles (shown in blue) are in the range of 1 to 100 nm It can be seen that the average size is small and uniformly distributed at 25 nm, and even in Example 2 in which the viscosity of the mixture is controlled by setting the temperature of the mixture to 32 to 38 ° C, the produced metal nanoparticles (marked in orange) are 1 In the range of ~100 nm, it can be seen that the average size is relatively small and uniformly distributed with an average size of 39 nm.

In contrast, in the case of a comparative example in which the viscosity of the mixture is controlled by setting the temperature of the mixture to 41 to 48 ° C, the generated metal nanoparticles (shown in gray) are out of the range of 1 to 100 nm and have an average size of 105 nm, which is relatively It can be seen that it is large and unevenly distributed.

As described above, the composite material having a carbon structure coated with the metal nanoparticles is 1 to 50% by weight of metal nanoparticles (eg, silver (Ag) nanoparticles) based on the total weight of the carbon nanoparticles. When the composite material is manufactured to have this coated structure and the average size of the coated metal nanoparticles is 1 to 100 nm, and this composite material is used as a negative electrode of an all-solid-state battery, the metal nanoparticles are During charging, the nucleation energy of lithium ions moving to the negative electrode is lowered so that lithium can be uniformly deposited on the current collector.

In the case of carbon nanoparticles, they separate the deposited lithium from the solid electrolyte and play a role in securing chemical stability. Accordingly, dendrite generation can be suppressed by reducing nucleation energy and minimizing lithium isolated in the process of electrodeposition and desorption of lithium ions on the negative electrode current collector. And, by overcoming the instability at the interface between the cathode and the solid electrolyte, an all-solid-state battery having high energy density and securing stability is possible. In particular, since the instability of a sulfide-based all-solid-state battery mainly occurs at the interface between the positive electrode and the electrolyte and the interface between the negative electrode and the electrolyte, an all-solid-state battery that has high energy density and secures stability by overcoming the instability at the interface between the negative electrode and the electrolyte. becomes possible

Due to the above effects, the composite material having a carbon structure coated with metal nanoparticles can be used as an anode material for an all-solid-state battery.

8 is a schematic cross-sectional view of an all-solid-state battery according to the present invention. As shown in FIG. 8, the all-solid-state battery according to the present invention includes a positive electrode 10, a negative electrode 20, and the positive electrode 10 and the negative electrode ( 20) and a solid electrolyte layer 30 interposed therebetween.

The positive electrode 10 includes a positive electrode current collector 12 and a positive electrode active material layer 14, and the negative electrode 20 includes a negative electrode current collector 22 and a negative electrode active material provided on at least one surface of the negative electrode current collector 22. layer 24. The positive electrode 10 may have a structure well known to those skilled in the art.

The negative electrode 20 includes the negative electrode current collector 22 and the negative electrode active material layer 24, and the negative electrode 20 is configured using a composite material having a carbon structure coated with the metal nanoparticles. do. In the conventional case, lithium metal has been used as the anode 20 to improve energy density. Lithium metal is expensive, has a slow reaction rate, and has problems in that coulombic efficiency (or charge/discharge efficiency) decreases and short circuits occur due to the growth of dendrites. there is.

The negative current collector 22 is not particularly limited as long as it does not cause chemical change in the all-solid-state battery and has high conductivity. For example, stainless steel, copper, aluminum, nickel, titanium, fired carbon, aluminum or It may include at least one selected from the group consisting of surface treatment of carbon, nickel, titanium, silver, etc. on the surface of stainless steel, and combinations thereof.

The negative electrode active material layer 24 may include a composite material layer having a carbon structure coated with the metal nanoparticles. The composite material having a carbon structure coated with the metal nanoparticles may be deposited on the surface of the anode current collector 22 to a certain thickness using a deposition method well known to those skilled in the art. Alternatively, it is also possible to form the negative active material layer 24 by compressing composite material powder or slurry coated with the metal nanoparticles to form a layered structure on the surface of the negative electrode current collector 22 .

If necessary, the negative electrode active material layer 24 may include a conductive material and a binder.

According to another embodiment, it is also possible to configure the negative electrode active material layer 24 to have a structure in which a solid electrolyte and a composite material having a carbon structure coated with the metal nanoparticles are dispersed.

Here, the solid electrolyte may include at least one of an organic solid electrolyte, an inorganic solid electrolyte, and a sulfide-based solid electrolyte. For example, a sulfide-based solid electrolyte having high ion conductivity of lithium ions may be applied.

The organic solid electrolyte may be a polymer solid electrolyte in which solvated lithium and a polymer material are mixed. The inorganic solid electrolyte includes an oxide-based solid electrolyte.

The sulfide-based solid electrolyte material contains sulfur (S) and has ionic conductivity of a metal belonging to group 1 or group 2 of the periodic table, and may include Li-PS-based glass or Li-PS-based glass ceramics.

Here, the solid electrolyte constituting the negative electrode active material layer 24 and the solid electrolyte included in the solid electrolyte layer 30 interposed between the positive electrode 10 and the negative electrode 20 of the all-solid-state battery are the same type or different from each other. It is possible to include it as a kind.

As described above, when the negative electrode 20 for an all-solid-state battery is constructed using the composite material having a carbon structure coated with the metal nanoparticles, unlike the prior art, the carbon structure coated with the metal nanoparticles is replaced with lithium metal. As the composite material is used as an anode material, dendrite generation can be suppressed by reducing the nucleation energy of lithium and minimizing the isolated lithium in the process of electrodeposition and desorption of lithium ions on the anode current collector. be able to

And, by overcoming the instability at the interface between the cathode and the solid electrolyte, an all-solid-state battery having high energy density and securing stability is possible. In particular, since the instability of a sulfide-based all-solid-state battery mainly occurs at the interface between the positive electrode and the electrolyte and the interface between the negative electrode and the electrolyte, an all-solid-state battery that has high energy density and secures stability by overcoming the instability at the interface between the negative electrode and the electrolyte. becomes possible

9 is a graph showing the charge/discharge efficiency (coulombic efficiency) of a battery using a composite material having a carbon structure coated with metal nanoparticles (silver nanoparticles) according to the present invention as an anode material.

The carbon-structured composite material coated with metal nanoparticles was composed by coating spherical silver nanoparticles with an average diameter of 1 to 100nm on elliptical carbon particles with an average diameter in the range of 1 to 500nm. , a negative electrode was manufactured using this composite material.

As shown in FIG. 9 , it can be seen that the charge/discharge efficiency is maintained at 99.88% even after 100 cycles of charge/discharge, and there is no decrease in charge/discharge efficiency.

The description of the above embodiment is merely an example with reference to the drawings for a more thorough understanding of the present invention, and should not be construed as limiting the present invention. In addition, it will be apparent to those skilled in the art that various changes and modifications are possible within a range that does not deviate from the basic principles of the present invention.

10: positive electrode 12: positive electrode current collector
14: positive electrode active material layer 20: negative electrode
22: negative electrode current collector 24: negative electrode active material layer
30: solid electrolyte layer

Claims (20)

A first step of preparing a mixture by dispersing carbon nanoparticles in a solvent;
A metal-containing precursor is added to the mixture so that the carbon nanoparticles are coated with the metal nanoparticles reduced from the metal-containing precursor, but the amount of the metal nanoparticles is 1 to 50% by weight based on 100% by weight of the carbon nanoparticles. And a second step of adjusting the amount of the metal-containing precursor so that it is coated on the carbon nanoparticles,
The mixture satisfies the following equation representing the correlation between temperature (°C) and viscosity (cP), and the metal nanoparticles coated on the carbon nanoparticles in the second step through viscosity control or temperature control of the mixture. A method of manufacturing a composite material having a carbon structure coated with metal nanoparticles, characterized in that the average size of the particles is controlled.

The method of claim 1,
The average size of the metal nanoparticles coated on the carbon nanoparticles in the second step is adjusted to 1 to 100 nm by controlling the viscosity of the mixture so that the temperature of the mixture is 20 to 40 ° C. Method for producing a composite material having a carbon structure coated with metal nanoparticles.
The method of claim 1,
In the second step, the metal nanoparticles are reduced from the metal-containing precursor to be coated on the carbon nanoparticles by using a Taylor flow method using a Kuett-Taylor reactor or an electron beam irradiation method that irradiates an electron beam. A method for producing a composite material having a carbon structure coated with metal nanoparticles.
The method of claim 1,
In the second step, a method for producing a composite material having a carbon structure coated with metal nanoparticles, characterized in that a reducing agent is added together when the metal-containing precursor is added to the mixture.
The method of claim 4,
The reducing agent is sodium borohydride (NaBH ₄ ), hydrazine (N ₂ H ₄ ), ascorbic acid (C ₆ H ₈ O ₆ ), hydroquinone (C ₆ H ₆ O ₂ ), citric acid (C ₆ H ₈ O ₇ ) and glucose (C ₆ H ₁₂ O ₆ ).
The method of claim 1,
After the second step, the method of manufacturing a composite material having a carbon structure coated with metal nanoparticles, characterized in that it further comprises the step of separating the carbon nanoparticles coated with metal nanoparticles from the mixture, drying and firing.
The method of claim 6,
The firing is a method for producing a composite material of a carbon structure coated with metal nanoparticles, characterized in that carried out for 1 hour to 24 hours at 300 ° C to 800 ° C in an inert or reducing gas atmosphere.
The method of claim 1,
Wherein the carbon nanoparticles are composed of at least one selected from carbon black, graphene, activated carbon, carbon fiber, acetylene black, ketjen black, and carbon nanotubes.
The method of claim 1,
The method of manufacturing a composite material having a carbon structure coated with metal nanoparticles, characterized in that the carbon nanoparticles have an average size of 1 to 500 nm.
The method of claim 1,
The solvent is any one selected from distilled water, methanol, ethanol, propanol, butanol, acetone, glycerol, and tetrahydrofuran, or a mixture of at least two of them. Preparation of a carbon structured composite material coated with metal nanoparticles method.
The method of claim 1,
The metal-containing precursor is a water-soluble precursor, and at least one is selected from oxide salts, oxyhydroxide salts, chloride salts, carbonates, acetates, citrates, nitrosilnitrates, nitrates, hydroxides, oxalates, carboxylates, and sulfates of metals. , A method for producing a composite material having a carbon structure coated with metal nanoparticles, characterized in that at least one is selected from an alkoxy precursor and an ammonium precursor containing a hydrocarbon as a lipophilic precursor.
The method of claim 1,
The metal contained in the metal-containing precursor is silver (Ag), platinum (Pt), palladium (Pd), gold (Au), iridium (Ir), osmium (Os), rhodium (Rh) and ruthenium (Ru). A method for producing a composite material having a carbon structure coated with metal nanoparticles, characterized in that the selected at least one metal.
The method of claim 1,
The method for producing a composite material having a carbon structure coated with metal nanoparticles, characterized in that the metal-containing precursor is a silver precursor containing silver (Ag).
The method of claim 1,
A method for producing a composite material having a carbon structure coated with metal nanoparticles, characterized in that the composite material having a carbon structure coated with the metal nanoparticles forms a negative electrode for an all-solid-state battery.
a negative electrode current collector;
A negative electrode active material layer formed on the negative electrode current collector,
In the negative electrode active material layer,
An anode for an all-solid-state battery, characterized in that it includes a composite material having a carbon structure coated with metal nanoparticles manufactured according to any one of claims 1 to 13.
The method of claim 15
The negative electrode active material layer is formed by depositing a composite material having a carbon structure coated with the metal nanoparticles on the surface of the negative electrode current collector to a predetermined thickness.
The method of claim 15
The negative electrode active material layer is formed in a layered structure on the surface of the negative electrode current collector by compressing powder or slurry of a composite material having a carbon structure coated with the metal nanoparticles.
The method of claim 15
A negative electrode for an all-solid-state battery, characterized in that the negative electrode active material layer has a structure in which a solid electrolyte and a composite material having a carbon structure coated with the metal nanoparticles are dispersed.
The method of claim 18
The solid electrolyte is an anode for an all-solid-state battery, characterized in that it comprises at least one of an organic solid electrolyte, an inorganic solid electrolyte and a sulfide-based solid electrolyte.
The method of claim 19
The solid electrolyte is a negative electrode for an all-solid-state battery, characterized in that the sulfide-based solid electrolyte.

Images