Method for manufacturing metal-supported catalyst for battery anode loaded with metal nanoparticles

Abstract

The present invention relates to a method for manufacturing a metal-supported catalyst. An embodiment of the present invention provides a method for manufacturing a metal-supported catalyst used in a battery, the method comprising: a first step for adding an amine compound to a metal salt or a metal acid to produce a metal precursor; a second step for preparing a carrier and adding the metal precursor produced in the first step to the carrier; a third step for mixing and aging the metal precursor-containing carrier obtained through the second step; a fourth step for drying the metal precursor-containing carrier completely mixed through the third step, thereby removing impurities, and reducing metal particles to generate a catalyst; and a fifth step for pulverizing the catalyst generated through the fourth step.

Description

Method for manufacturing a metal-supported catalyst for a battery anode supported with metal nanoparticles

[0001] The present invention relates to a method for manufacturing a metal-supported catalyst, and more specifically, to a method for manufacturing a metal-supported catalyst for a battery anode (negative electrode) in which metal nanoparticles are supported on a carrier.

[0002] A lithium-ion battery is an electrochemical device composed of a cathode, an anode, and an electrolyte, and these three elements play a role in storing and releasing energy through the movement of lithium ions.

[0003] In lithium-ion batteries, energy is stored and released by repeatedly performing charging, in which lithium ions move from the positive electrode to the negative electrode to store energy, and discharging, in which lithium ions move from the negative electrode to the positive electrode to generate current and release energy during this process.

[0004] In this case, carbon is primarily used as the anode (negative electrode) of lithium-ion batteries. As the main material for the battery negative electrode, carbon provides a structure capable of absorbing and storing lithium ions. Furthermore, this carbon material reacts well with lithium ions in a solid state and offers high electrical conductivity and stability.

[0005] However, when using only carbon in the anode as in this way, it was difficult to suppress lithium dendrite formation (tree-branch shaped crystals that form when using lithium-ion batteries). In addition, conventional methods for manufacturing metal nanocatalysts required a separate reduction process and additional reducing agents, which increased process costs.

[0006] The present invention provides a method for manufacturing a metal-supported catalyst for an anode that can be used in the anode (negative electrode) of a battery to suppress lithium dendrite formation and improve battery performance.

[0007] In addition, a method for manufacturing a metal-supported catalyst is presented, which can be manufactured in a simple manner without a separate reduction process by utilizing an amine compound or an aldehyde compound.

[0008] Other detailed objectives of the present invention will be clearly understood and grasped by experts or researchers in the art through the specific details described below.

[0009] To solve the above problem, the present invention provides, as an example, a method for manufacturing a metal-supported catalyst used in a battery, comprising: a first step of preparing a metal precursor by adding an amine compound to a metal salt or a metal acid; a second step of preparing a carrier and introducing the metal precursor prepared in the first step into the carrier; a third step of mixing and aging the carrier into which the metal precursor obtained through the second step has been introduced; a fourth step of drying the carrier into which the metal precursor introduced after mixing through the third step has been completed to remove impurities and simultaneously reduce metal particles to produce a catalyst; and a fifth step of grinding the catalyst produced through the fourth step.

[0010] Here, the metal precursor manufactured in the first step above may be a silver precursor.

[0011] In addition, the carrier used in the second step above may be a carbon carrier.

[0012] Meanwhile, the amine compound used in the first step above may be at least one of MEA (Monoethanolamine), TEA (Triethanolamine), and DEA (Diethanolamine).

[0013] According to an embodiment of the present invention, a metal-supported catalyst can be easily manufactured without the need for filtration and reduction processes by utilizing an amine compound or an aldehyde compound, and the charge and discharge efficiency and durability of a battery using such a metal-supported catalyst can be improved.

[0014] In addition, the metal-supported catalyst prepared according to the embodiment of the present invention can suppress lithium dendrite formation and improve the initial performance and durability of the battery when used in a battery anode.

[0015] Other effects of the present invention will be clearly grasped and understood by experts or researchers in the art through the specific details described below or during the process of implementing the present invention.

[0016] FIG. 1 is a flowchart illustrating a method for manufacturing a metal-supported catalyst for a battery anode according to an embodiment of the present invention.

[0017] FIG. 2 is a diagram showing the size of Ag / C catalyst particles prepared according to an embodiment of the present invention.

[0018] FIG. 3 is a diagram showing the lattice type of Ag / C catalyst particles prepared according to an embodiment of the present invention.

[0019] Figure 4 is a TEM image showing the catalyst particle size of Ag / C prepared according to an embodiment of the present invention.

[0020] Figure 5 is an EDS photograph showing the catalyst particle size of Ag / C prepared according to an embodiment of the present invention.

[0021] FIG. 6 is a graph showing the distribution of Ag / C catalyst particles prepared according to an embodiment of the present invention.

[0022] FIG. 7 is a graph showing the results of evaluating the initial charge-discharge efficiency of an Ag / C catalyst prepared according to an embodiment of the present invention.

[0023] FIG. 8 is a graph showing the durability evaluation results of an Ag / C catalyst prepared according to an embodiment of the present invention.

[0024] FIG. 9 is a diagram showing the operation of an Ag / C catalyst prepared according to an embodiment of the present invention in a battery.

[0025] The features and effects of the present invention described above will become clearer through the following detailed description in conjunction with the attached drawings, and accordingly, a person skilled in the art to which the present invention pertains will be able to easily implement the technical concept of the present invention. Since the present invention is susceptible to various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to specific disclosed forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention. The terms used in this application are used merely to describe specific embodiments and are not intended to limit the present invention.

[0026] Hereinafter, a method for manufacturing a metal-supported catalyst according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0027] A method for manufacturing a metal-supported catalyst according to an embodiment of the present invention comprises the steps of: i) manufacturing a metal precursor; ii) mixing the metal precursor and a carrier; iii) aging the mixed metal precursor and carrier; iv) drying the generated catalyst; and v) grinding the dried catalyst.

[0028] Each step below is described in detail with reference to the drawings.

[0029] FIG. 1 is a flowchart illustrating a method for manufacturing a metal-supported catalyst for a battery anode according to an embodiment of the present invention.

[0030] As a first step, a metal precursor is manufactured (101)

[0031] Metal precursors serve to provide metal particles supported on a carrier. The metal particles for the battery anode are not specific, and any metal capable of alloying and reversible reactions with lithium-friendly properties may be used. Various metals such as Ag (silver), Au (gold), Ru (ruthenium), Rh (rhodium), Ni (nickel), Sn (tin), Mg (magnesium), and Zn (zinc) can be used as metal particles. In particular, it is most appropriate to support nano-sized Ag on the carrier.

[0032] In this manner, the metal precursor supplying the metal particles is not limited to a specific metal, but the present invention describes the use of Ag metal capable of alloying and reversibly reacting with Li (lithium).

[0033] Various types of precursors can be used for the application of Ag metal. The precursors are not limited to metal salts or metal acids, such as silver acetate (Ag Acetate), silver oxalate (Ag Oxalic Acid), silver chloride (Ag Chloride), and silver nitrate (Ag Nitrate).

[0034] Silver nitrate was used in the following embodiments of the present invention. Silver nitrate can be dissolved in various solvents, and a complex ionizing agent may be added as needed for complex ionization. Specifically, the complex ionizing agent is a substance such as ammonia (NH3) and carbon monoxide (CO), but is not limited to specific substances.

[0035] In addition, various amine compounds, alcohol compounds, etc., can be used in addition to the metal precursor, and it is preferable to use amine compounds. The amine compounds used may be primary amine compounds such as MEA (monoethanolamine), TEA (triethanolamine), and DEA (diethanolamine), and if necessary, a mixture of two substances such as secondary amine compounds may be used.

[0036] These amine compounds have the advantage of easily reducing metal nanoparticles during the drying process, eliminating the need for an additional reduction process. Depending on the ratio of the added amine compounds, the particle size can vary, and when forming Ag nanoparticles, the particle size can be controlled, allowing for the formation of smaller Ag nanoparticles.

[0037] Meanwhile, the concentration of the amine compound is suitable for 1 to 6 M, and 1 to 3 M is more preferable. If the concentration of the amine compound is less than 1 M, the reducing power of Ag decreases and oxygen compounds such as Ag2O and AgO may be formed. In addition, if it is higher than 6 M, the impurity content increases due to the excessive amine compound, and coarsening of Ag particles on the surface of the carrier may occur.

[0038] Although the metal content used in this invention is not specified, 5 to 50 wt% is appropriate, and more appropriately, 5 to 25 wt% is appropriate. If the content is lower than 5 wt%, the battery performance and the effect of suppressing Li dendrite formation may be negligible. If the metal content is higher than 50 wt%, the aggregation of metal nanoparticles intensifies, making it difficult to expect high performance of the battery.

[0039] In the second step, the precursor and the carrier are mixed (102)

[0040] To this end, a carrier is prepared. The carrier material used is not limited, and any material capable of bonding with Li, such as magnesium oxide (MgO), silicon, and carbon, can be used. In this case, carbon is suitable as it is used in existing anodes and can bond with Li. Carbon is a widely used material in anodes and can store Li, allowing it to properly perform charging and discharging functions.

[0041] The particle size of carbon is preferably approximately 40 to 80 nm. In the case of larger particles, the mobility of Li may be reduced due to the expansion of the storage material. This decreases the charge and discharge performance of the battery. Particles smaller than 40 nm make it difficult to store sufficient Li.

[0042] A metal precursor is introduced into and mixed with such a support. The mixing of the prepared metal precursor and the support is not limited to a specific reactor, and a catalyst for an anode can be prepared using various reactors such as ribbon mixers and planetary mixers.

[0043] The manufactured metal precursor can be added to the carrier in the form of droplets to ensure uniform dispersion. A pump can be used for this droplet dispersion, and it is preferable to use a metering pump to add the precursor to the carrier.

[0044] Although the dropwise addition rate of the solution is not limited, it must be carried out at the slowest possible speed to ensure uniform dispersion on the support. To this end, a calibrated peristaltic pump can be used to dropwise add the metal precursor. Through this process, a metal-supported catalyst can be produced.

[0045] In the third step, the generated catalyst is mixed and aged (103)

[0046] The catalyst, having completed the dropwise addition of the precursor according to the above-described process, is subjected to continuous mixing and aging to ensure that metal particles are uniformly distributed on the surface of the support. Aging is not limited to a specific time, but the longer the aging process, the higher the degree of metal dispersion.

[0047] However, since an excessively long time can increase the catalyst manufacturing process time and result in an inefficient catalyst manufacturing system, mixing and maturation must be carried out according to an appropriate time.

[0048] The shape of the impeller used for mixing is not limited to ribbon, 3-way, 4-way, sawtooth type, etc. The stirring speed of the impeller should be performed at a speed at which the powder vortex is properly formed.

[0049] The temperature suitable for catalyst preparation is room temperature (20~25 o C) is the optimal temperature, and if the temperature is higher, metal nanoparticles may aggregate. When mixing and aging at a temperature lower than the optimal temperature, it is difficult to expect uniform dispersion of the metal precursor. Therefore, a jacketed reactor was used to maintain a constant temperature.

[0050] In the fourth step, the mixed catalyst is dried (104)

[0051] The catalyst, once mixed, can have impurities removed through a drying process. The drying method is not specified, such as a vacuum oven or a convection oven, but preferably, a vacuum oven can be used. Additionally, when using a convection oven, drying can be performed in a nitrogen (N2) atmosphere.

[0052] The appropriate drying temperature is 40 to 120°C, and more preferably 60 to 100°C. At temperatures lower than 40°C, volatile substances or moisture cannot evaporate, making it difficult to perform charging and discharging smoothly and potentially degrading battery performance. At temperatures higher than 120°C, coarsening occurs due to the aggregation of metal (Ag) particles, and the viscosity of the anode slurry increases, which may make battery manufacturing difficult.

[0053] The drying time is not specified, but can be performed for 6 to 24 hours. If the drying time is less than 6 hours, it is difficult for catalyst impurities to volatilize. If drying is 24 hours or longer, the time required for the catalyst manufacturing process increases, and aggregation of metal nanoparticles may occur.

[0054] Meanwhile, through a drying process, the amine compound added to the precursor reduces metal ions into metal particles. At this time, the reduced metal particles need to be controlled to an appropriate size. It is preferable that the metal nanoparticles used in the present invention have a size of 200 nm or less. In particular, when using silver nanoparticles, the particle size is 100 nm or less, preferably 10 to 80 nm, and more preferably 30 to 60 nm.

[0055] In addition, the surface state of the metal nanoparticles used must be free of oxygen. This is because Li ions can combine with oxygen to form Li2O during the charging and discharging process. Such irreversible reactions can accelerate the dendrite formation of Li. Therefore, to suppress oxygen penetration of the Ag / C catalyst during the drying process, it is effective to use a vacuum oven instead of a convection oven.

[0056] In this way, an amine compound is added during the precursor manufacturing process, and as impurities volatilize during the drying process, the amine compound reduces Ag, allowing the catalyst to be produced without a separate reduction process. Additionally, the particle size of the metal ions can be appropriately controlled by using an amine compound at an appropriate concentration and drying at an appropriate temperature.

[0057] In the fifth step, the manufactured catalyst is crushed (105)

[0058] The manufactured catalyst can be pulverized through grinding. The grinding method used in the grinding process is not limited. For example, the pulverization of the dried catalyst can be performed using a high-speed mixer.

[0059] Grinding is a process of adjusting the metal-supported catalyst formed after reduction to an appropriate particle size. By controlling the particle size of the catalyst through the grinding process, the reaction surface area increases and catalyst efficiency is improved. The more uniform the particle size of the catalyst, the more consistent performance can be guaranteed in the reaction. To make the catalyst particles uniform, the grinding process can be performed 1 to 2 times for 1 to 2 minutes to obtain the final metal-supported catalyst.

[0060] A metal-supported catalyst can be manufactured through such a manufacturing process (106). Fig. 10 shows an Ag / C catalyst as an example of such a metal-supported catalyst. Referring to the figure, the manufactured Ag / C catalyst has silver nanoparticles supported on carbon and shows the movement of lithium ions during charging and discharging.

[0061] In the drawing, Ag supported on carbon is a lithiated material that has an ionic radius similar to that of Ag, allowing it to alloy and store Li ions like carbon, thereby improving battery performance.

[0062] Next, an example of a method for manufacturing according to one embodiment of the present invention will be described in detail. The following example is merely illustrative of one form of the present invention, and the scope of the present invention is not limited by the following example.

[0063] 1) Catalyst supported with metal nanoparticles (Example 1)

[0064] A metal precursor was prepared by adding 1M silver nitrate (Ag nitrate) and 1M MEA (amine compound). Meanwhile, carbon (Super P, Emeris) was prepared as a support and introduced into a double-jacketed reactor. To mix and mature the metal precursor, the Ag precursor was added to the carbon using a peristaltic pump. At this time, the temperature of the double-jacketed reactor was set to 25 ℃, and the Ag precursor was introduced to ensure 15 wt% Ag was supported. To ensure uniform Ag support, the catalyst was matured for 12 hours to produce an Ag / C catalyst. Subsequently, the catalyst was dried in a vacuum oven at 80 ℃ for 12 hours. The Ag / C catalyst was micronized through a grinding process, and finally, a 15 wt% Ag / C catalyst was prepared.

[0065] 2) Catalyst supported with metal nanoparticles (Example 2)

[0066] A 15wt% Ag / C catalyst was prepared by carrying out the process in the same manner as in Example 1, except that a metal precursor was prepared by adding 1M MEA to 3M silver nitrate.

[0067] 3) Catalyst supported with metal nanoparticles (Example 3)

[0068] A 15wt% Ag / C catalyst was prepared by carrying out the process in the same manner as in Example 1, except that a metal precursor was prepared by adding 1M MEA to 6M silver nitrate.

[0069] Evaluation example

[0070] For the Ag / C catalysts prepared according to Examples 1 to 3, the particle shape, particle size, and dispersion of Ag were measured, and the characteristics when used as electrodes for secondary batteries were measured and evaluated.

[0071] Ag particle size and crystal structure (XRD)

[0072] The crystallinity and particle size of the Ag / C catalyst were analyzed using an X-ray diffractometer (XRD, SmartLab High Temp, Rigaku, Tokyo, Japan) and copper Kα radiation (CuKa radiation, λ 0.154 nm). Measurements were performed in the 2θⅸ range of 5–90 o Lo 5 o The process was conducted at intervals of / min. In addition, the general-purpose pattern analysis program SmartLab Program was utilized to verify the crystal structure pattern of the sample. The particle size was calculated using the Scherrer Equation as shown below.

[0073]

[0074] The crystallinity of Ag supported on a carbon carrier was referenced from JCPDS NO. 04-0783. The results of the above analysis are shown in Figures 2 and 3.

[0075] Referring to Fig. 2, it was confirmed that the particle size of Example 1, in which MEA was used as the amine compound, was the smallest, followed by DEA and TEA, but all had appropriate particle sizes ranging from 1 to 60 nm. Fig. 3 shows the analysis results of Example 1, in which MEA, an amine compound, was added. The prepared Ag / C catalyst was dried without a separate reduction process, and then XRD crystallinity analysis was performed. As a result of the measurement, a peak corresponding to Ag metal was observed. This indicates that spontaneous reduction of Ag is possible by drying alone without a reduction process.

[0076] Ag particle shape, size, and dispersion (TEM, EDS)

[0077] Transmission Electron Microscope (TEM) and Energy Dispersive X-ray Spectroscopy (EDS) (JEM-ARM200F, NEOARM) analysis was performed to determine the particle shape and size of Ag supported on the carbon support of the Ag / C catalyst prepared according to Example 1. The results are shown in Figures 4 and 5.

[0078] Referring to Figure 4, which shows the results of TEM analysis, it was confirmed that Ag nanoparticles were supported on the carbon carrier. Meanwhile, referring to Figure 5, which shows the results of EDS analysis, it was confirmed that the Ag supported on the carbon carrier was dispersed in the form of nanoparticles without aggregating. As such, the Ag dispersion is Li + It can facilitate the movement of. In the case of aggregated Ag, Li + It can reduce the mobility of and consequently degrade secondary battery performance. In the case of highly dispersed Ag, Li has a large surface area + The probability of combining with is improved, which can improve the charge and discharge performance of the secondary battery.

[0079] Meanwhile, to confirm the distribution of Ag particles, an Ag / C catalyst was mixed with 50 ml of ethanol in a vial, placed on a copper grid, and ultrasonically dispersed for 1 minute. In addition, to confirm the distribution of Ag nanoparticles, the size of 100 particles was measured, and the particle distribution results are shown in Figure 6.

[0080] The average particle size was measured based on 100 Ag nanoparticles observed by TEM analysis. Referring to Figure 6, the average particle size was measured to be approximately 30–40 nm. In particular, Ag particle sizes larger than 80 nm are unsuitable as they can induce anode expansion during the charging and discharging process. Ag nanoparticles smaller than 10 nm are applied to the surface of the carbon support. +A large number of them may exist, and amorphous Ag is formed, which lowers the charge and discharge efficiency of the secondary battery. In addition, it can cause a short circuit during the continuous charge and discharge process. In the present invention, it was confirmed that the Ag / C catalyst was manufactured with an Ag nanoparticle size in the range of 10 to 80 nm, which is an appropriate size.

[0081] Secondary battery electrode evaluation (anode)

[0082] To evaluate the anode electrode, 4g of the Ag / C catalyst prepared in Example 1 and 4g of an NMP solution containing 7 wt% of PVdF (polyvinylidene fluoride) were placed in a Thinky mixer container and mixed three times for 6 minutes each at 1,500 rpm. Subsequently, a monocell was prepared by depositing the Ag / C catalyst slurry onto a SUS foil. The charge-discharge cycle characteristics of the monocell were evaluated under operating voltage ranges of 4.25V-3.0V and operating temperatures of 60℃, and the results are shown in Figures 7 and 8.

[0083] Figure 7 shows the results of the initial charge-discharge experiment based on a 0.1C standard (charge time 10 hours), confirming that no adverse reactions or short circuits occurred. In addition, Figure 8 shows the results of the charge-discharge durability evaluation of the secondary battery based on a 0.33C standard (charge time 7 hours), showing stable performance up to 30 charge-discharge cycles.

[0084] Although the detailed description of the present invention described above has been explained with reference to preferred embodiments of the invention, those skilled in the art or those with ordinary knowledge in the relevant technical field will understand that various modifications and changes can be made to the present invention without departing from the spirit and technical scope of the invention as described in the claims set forth below.

Claims

1. A method for manufacturing a metal-supported catalyst used in a battery, A first step of preparing a metal precursor by adding an amine compound to a metal salt or metal acid, A second step of preparing a carrier and introducing the metal precursor prepared in the first step into the carrier, A third step of mixing and aging a carrier into which the metal precursor obtained through the second step above has been introduced, A fourth step of drying a carrier into which the metal precursor mixed through the third step has been introduced to remove impurities while simultaneously reducing metal particles to produce a catalyst, and Step 5, grinding the catalyst generated through Step 4. A method for manufacturing a metal-supported catalyst comprising 2. In Paragraph 1, A method for manufacturing a metal-supported catalyst characterized in that the metal precursor manufactured in the first step is a silver precursor.

3. In Paragraph 2, A method for manufacturing a metal-supported catalyst characterized in that the carrier used in the second step above is a carbon carrier.

4. In Paragraph 1, A method for preparing a metal-supported catalyst, characterized in that the amine compound used in the first step above is at least one of MEA (Monoethanolamine), TEA (Triethanolamine), and DEA (Diethanolamine).

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