Manufacturing method of Prussian blue cathode material for sodium batteries using a Taylor reactor

Abstract

The present invention relates to a method for manufacturing a Prussian blue cathode material for sodium batteries using a Taylor reactor. More specifically, the method includes a first mixture preparation step of preparing a first mixture containing an aqueous iron chloride solution, a second mixture preparation step of preparing a second mixture containing an aqueous sodium ferrocyanide solution, a synthesis step of introducing the mixtures prepared in the first mixture preparation step and the second mixture preparation step into a Taylor reactor and reacting them under nitrogen injection conditions to synthesize a Prussian blue analog, a aging step of aging the Prussian blue analog prepared in the synthesis step, a washing and filtration step of washing and filtration the aged Prussian blue analog with a detergent, and a drying step of drying the washed and filtrated Prussian blue analog. The method for manufacturing a Prussian blue cathode material for sodium batteries using the above steps provides a Prussian blue cathode material that exhibits excellent production efficiency and provides sodium batteries with improved charge / discharge efficiency and capacity retention.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a Prussian blue cathode material for sodium batteries using a Taylor reactor, and to a method for producing a Prussian blue cathode material for sodium batteries using a Taylor reactor that exhibits excellent production efficiency for Prussian blue cathode materials and provides sodium batteries with improved charge / discharge efficiency and capacity retention. [Background technology]

[0002] 2. Description of the Related Art In recent years, there has been a significant increase in demand for secondary cells as a power supply source for personal portable terminal devices such as mobile phones and tablet PCs, and for machinery such as hybrid electric vehicles and plug-in electric vehicles.

[0003] Conventionally, lithium secondary batteries have been most commonly used as power supply devices for machines such as the above-mentioned personal portable terminal devices and electric vehicles. However, because lithium secondary cells use large amounts of rare metals such as cobalt (Co), nickel (Ni), manganese (Mn), and lithium (Li), there has been a problem in that the supply of rare metals is not smooth due to the increasing demand for large secondary batteries.

[0004] In order to solve the above problems and reduce the manufacturing cost of secondary batteries, development is underway on sodium secondary cells, which are inexpensive and cost about one-sixth the cost of lithium secondary batteries. Sodium secondary batteries can be made from inexpensive materials that are in abundant supply, and commercialization of these batteries is expected to enable the mass supply of secondary batteries.

[0005] A sodium secondary battery is a secondary battery containing an electrolyte, and is composed of a positive electrode and a negative electrode, each containing a positive electrode active material and a negative electrode active material capable of charging and discharging sodium (Na) ions, and an electrolyte containing sodium ions. In such a sodium secondary battery, sodium ions travel back and forth between the negative electrode and the positive electrode through the electrolyte, similar to the lithium ions in a lithium secondary battery. Charging refers to the doping of sodium ions into the negative electrode active material, and discharging refers to the removal of sodium ions from the negative electrode active material.

[0006] Recently, attempts have been made to use Prussian blue, which exhibits excellent cycle life, low cost, and high speed, as a positive electrode active material for such sodium secondary batteries. However, a method using a stirring tank has been used in the production of Prussian blue.

[0007] However, conventional production methods using a stirring tank have had problems such as low productivity of Prussian blue and low charge / discharge efficiency and capacity retention rate of the Prussian blue produced.

[0008] The background technology of the present invention is disclosed in Korean Patent Registration No. 10-2266574 (2021.06.14) and Korean Patent Registration No. 10-2406480 (2022.06.02). Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor, which shows excellent production efficiency for the Prussian blue cathode material and can provide a sodium battery with improved charge / discharge efficiency and capacity retention. [Means for solving the problem]

[0010] The object of the present invention is achieved by providing a method for manufacturing a Prussian blue cathode material for a sodium battery using a Taylor reactor, the method comprising: a first mixture-preparing step of preparing a first mixture containing an aqueous iron chloride solution; a second mixture-preparing step of preparing a second mixture containing an aqueous sodium ferrocyanide solution; a synthesis step of introducing the mixture prepared in the first mixture-preparing step and the mixture prepared in the second mixture-preparing step into a Taylor reactor and reacting them under nitrogen injection conditions to synthesize a Prussian blue analog; an aging step of maturing the Prussian blue analog prepared in the synthesis step; a washing / filtration step of washing and filtering the Prussian blue analog matured in the aging step with a detergent and filtering it; and a drying step of drying the Prussian blue analog washed and filtered in the washing / filtration step.

[0011] According to a preferred feature of the present invention, the first mixture preparation step is carried out by mixing 0.001 to 4 M trisodium citrate with 0.001 to 6 M aqueous iron chloride solution containing nitrogen-purged distilled water.

[0012] According to a more preferred feature of the present invention, the second mixture preparation step is carried out by mixing 0.001 to 4 M trisodium citrate with 0.001 to 1 M aqueous sodium ferrocyanide solution containing nitrogen-purged distilled water.

[0013] According to a more preferred aspect of the present invention, the synthesis step is carried out by adding 100 parts by weight of the mixture prepared in the first mixture preparation step and 80 to 120 parts by weight of the mixture prepared in the second mixture preparation step to a Taylor reactor and stirring at a temperature of 10 to 100°C and a speed of 50 to 1500 rpm for 1 to 1440 minutes.

[0014] According to a further preferred feature of the present invention, the drying step is carried out at a temperature of 40 to 130° C. for 10 to 30 hours. [Effects of the Invention]

[0015] The method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor according to the present invention exhibits excellent production efficiency for the Prussian blue cathode material and has the outstanding effect of providing a Prussian blue cathode material that can be used to produce a sodium battery with improved charge / discharge efficiency and capacity retention. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a flowchart illustrating a method for manufacturing a Prussian blue cathode material for a sodium battery using a Taylor reactor according to the present invention.

[0017] [Figure 2] 1 is a schematic diagram showing the reaction process of Prussian blue analogues that proceeds in the synthesis steps of the present invention.

[0018] [Figure 3] 1 is a photograph showing Prussian blue cathode materials prepared in Examples 1 to 4 of the present invention, taken by SEM.

[0019] [Figure 4] 1 is a photograph showing Prussian blue cathode materials prepared in Comparative Examples 1 to 4 of the present invention, taken by SEM.

[0020] [Figure 5] 1 is a graph showing XRD patterns of Prussian blue cathode materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 of the present invention. [Figure 6] 1 is a graph showing XRD patterns of Prussian blue cathode materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 of the present invention. [Figure 7] 1 is a graph showing XRD patterns of Prussian blue cathode materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 of the present invention. [Figure 8] 1 is a graph showing XRD patterns of Prussian blue cathode materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 of the present invention.

[0021] [Figure 9] 1 is a graph showing the measured charge / discharge capacity of Prussian blue cathode materials prepared in Examples 1, 3, and 4 of the present invention and Comparative Examples 1 to 3.

[0022] [Figure 10] 1 is a graph showing test results of charge / discharge capacity of Prussian blue cathode materials prepared in Examples 1, 3, and 4 of the present invention and Comparative Examples 1 to 3.

[0023] [Figure 11] 1 is a graph showing the measured capacity retention rates of Prussian blue cathode materials prepared in Examples 1, 3, and 4 of the present invention and Comparative Examples 1 to 3. BEST MODE FOR CARRYING OUT THE INVENTION

[0024] Hereinafter, preferred examples of the present invention and the physical properties of each component will be described in detail. However, this is intended to provide a detailed description to the extent that a person skilled in the art to which the present invention pertains can easily carry out the invention, and is not intended to limit the technical concept and scope of the present invention.

[0025] The method for manufacturing a Prussian blue cathode material for a sodium battery using a Taylor reactor according to the present invention includes a first mixture preparation step (S101) of preparing a first mixture containing an aqueous iron chloride solution; a second mixture preparation step (S101-1) of preparing a second mixture containing an aqueous sodium ferrocyanide solution; a synthesis step (S103) of introducing the mixture prepared in the first mixture preparation step (S101) and the mixture prepared in the second mixture preparation step (S101-1) into a Taylor reactor and reacting them under nitrogen injection conditions to synthesize a Prussian blue analog; an aging step (S105) of aging the Prussian blue analog prepared in the synthesis step (S103); a washing and filtration step (S107) of washing and filtering the Prussian blue analog aged in the aging step (S105) with a detergent and filtering it; and a drying step (S109) of drying the Prussian blue analog washed and filtered in the washing and filtration step (S107).

[0026] The first mixture preparation step (S101) is a step of preparing a first mixture containing an aqueous iron chloride solution (FeCl2·4H2O), and preferably comprises a process of preparing the first mixture by mixing trisodium citrate and an aqueous iron chloride solution, and more preferably, the first mixture is prepared by mixing 0.001 to 4 M trisodium citrate with 0.001 to 6 M aqueous iron chloride solution containing nitrogen-purged distilled water, and stirring at a speed of 800 to 900 rpm.

[0027] In this case, the nitrogen-purged distilled water is more preferably obtained by injecting nitrogen into distilled water at a rate of 18 to 22 cc / min.

[0028] The second mixture preparation step (S101-1) is a step of preparing a second mixture containing an aqueous sodium ferrocyanide solution (NaFe(CN)·10H0), and preferably comprises a process of preparing the second mixture by mixing an aqueous sodium ferrocyanide solution containing trisodium citrate and nitrogen-purged distilled water, and more preferably, the second mixture is prepared by mixing 0.001 to 4 M trisodium citrate with 0.001 to 1 M aqueous sodium ferrocyanide solution containing nitrogen-purged distilled water, and stirring at a speed of 800 to 900 rpm.

[0029] In this case, the nitrogen-purged distilled water is more preferably obtained by injecting nitrogen into distilled water at a rate of 18 to 22 cc / min.

[0030] The synthesis step (S103) is a step of synthesizing a Prussian blue analog by adding the mixture prepared through the first mixture preparation step (S101) and the mixture prepared through the second mixture preparation step (S101-1) to a Taylor reactor and reacting them under nitrogen injection conditions. Preferably, the synthesis step (S103) is carried out by adding 100 parts by weight of the mixture prepared through the first mixture preparation step (S101) and 80 to 120 parts by weight of the mixture prepared through the second mixture preparation step (S101-1) to a Taylor reactor and stirring at a temperature of 10 to 100°C and a speed of 50 to 1500 rpm for 10 to 1200 minutes.

[0031] The Prussian blue analog is synthesized through the synthesis step (S103), and it is more preferable that the nitrogen injection is carried out under the condition of 18 to 22 cc / min.

[0032] The reaction process of the Prussian blue analogue that proceeds in the synthesis step (S103) is carried out by a coprecipitation method, and the reaction process of the Prussian blue analogue that proceeds by the coprecipitation method is shown in Reaction Scheme 1 and FIG. 2 below.

[0033] <Reaction Scheme 1>

[0034] TIFF2026503894000002.tif13154

[0035] In the synthesis step of the present invention, as shown in Reaction Scheme 1, a first mixture containing iron ions is reacted with a second mixture containing ferrocyanide to synthesize the final product, a Prussian blue analog (NaFe(CN)).

[0036] Coprecipitation is a phenomenon in which a substance is precipitated together with other substances. It refers to a method in which several different ions are precipitated together in an aqueous or non-aqueous solution, and is the most commonly used method for producing precursors.

[0037] The aging step (S105) is a step of aging the Prussian blue analogue synthesized through the synthesis step (S103), and preferably comprises a step of wrapping the Prussian blue analogue synthesized through the synthesis step (S103) in parafilm at room temperature without stirring or heating and aging it in a desiccator for 22 to 26 hours.

[0038] After the aging step (S105) consisting of the above processes, the performance of the synthesized Prussian blue cathode material can be improved.

[0039] The washing and filtering step (S107) is a step of washing and filtering the Prussian blue analogue matured in the aging step (S105) with a detergent, and preferably includes a process of washing 100 parts by weight of the Prussian blue analogue matured in the aging step (S105) with 650 to 700 parts by weight of a detergent two to three times.

[0040] In this case, the cleaning agent is preferably a mixture of 100 parts by weight of distilled water and 1 to 1.5 parts by weight of trisodium citrate, and after the completion of the cleaning, it is preferable to carry out a filtration process using a centrifuge or a continuous centrifuge and an SS filter.

[0041] The drying step (S109) is a step of drying the Prussian blue analogue washed and filtered through the washing and filtering step (S107), and is preferably performed at a temperature of 40 to 130°C for 10 to 30 hours.

[0042] In this case, the apparatus used for drying is not particularly limited, and various equipment can be used, but a vacuum oven, a continuous dryer, etc. can be used. When drying a small amount, it is efficient to use a vacuum oven, and when drying a large amount, it is preferable to use a continuous dryer.

[0043] Hereinafter, a method for manufacturing a Prussian blue cathode material for a sodium battery using a Taylor reactor according to the present invention and physical properties of the Prussian blue cathode material for a sodium battery manufactured by the method will be described with reference to examples.

[0044] <Production Example 1> Production of first mixture

[0045] 2M trisodium citrate was mixed with 3M aqueous iron chloride solution containing distilled water purged with nitrogen (20 cc / min) and stirred at a speed of 850 rpm to prepare a first mixture.

[0046] <Production Example 2> Production of second mixture

[0047] A second mixture was prepared by mixing 2M trisodium citrate with 0.5M aqueous sodium ferrocyanide solution containing nitrogen-purged (20cc / min) distilled water and stirring at a speed of 850 rpm.

[0048] Comparative Preparation Example 1: Preparation of second mixture

[0049] A second mixture was prepared by mixing 2M trisodium citrate with 0.5M aqueous sodium ferrocyanide solution and stirring at a speed of 850 rpm.

[0050] Example 1

[0051] 100 parts by weight of the first mixture prepared in Preparation Example 1 and 100 parts by weight of the second mixture prepared in Preparation Example 2 were introduced into a Taylor reactor and stirred at 80°C and 600 rpm for a residence time of 1τ under nitrogen purging conditions (20 cc / min). A Prussian blue analog was synthesized. The synthesized Prussian blue analog was wrapped in parafilm and aged in a desiccator for 24 hours. The aged Prussian blue analog was washed twice with a cleaning solution, introduced into a centrifuge, centrifuged at 8,500 rpm for 5 minutes, and filtered. The filtered Prussian blue analog was introduced into a vacuum oven and dried at 120°C for 24 hours to produce a Prussian blue cathode material for a sodium battery.

[0052] <Example 2>

[0053] The same procedure as in Example 1 was carried out, but the residence time was set to 4τ to prepare a Prussian blue cathode material for a sodium battery.

[0054] Example 3

[0055] The same procedure as in Example 1 was carried out, but the residence time was set to 5τ to prepare a Prussian blue cathode material for a sodium battery.

[0056] Example 4

[0057] The same procedure as in Example 1 was carried out, but the residence time was set to 6τ to prepare a Prussian blue cathode material for a sodium battery.

[0058] <Comparative Example 1>

[0059] 100 parts by weight of the first mixture prepared in Preparation Example 1 and 100 parts by weight of the second mixture prepared in Comparative Preparation Example 1 were placed in a reaction tank and reacted at 80°C and 850 rpm for 1 hour under nitrogen purging conditions (20 cc / min), to synthesize a Prussian blue analog. The synthesized Prussian blue analog was wrapped in parafilm and aged in a desiccator for 24 hours. The aged Prussian blue analog was washed twice with a cleaning solution, placed in a centrifuge, centrifuged at 8,500 rpm for 5 minutes, and filtered. The filtered Prussian blue analog was placed in a vacuum oven and dried at 120°C for 24 hours to prepare a Prussian blue cathode material for a sodium battery.

[0060] <Comparative Example 2>

[0061] The same procedure as in Comparative Example 1 was carried out, but the reaction was carried out in a reaction tank for 4 hours to prepare a Prussian blue cathode material for a sodium battery.

[0062] <Comparative Example 3>

[0063] The same procedure as in Comparative Example 1 was carried out, but the reaction was carried out in a reaction tank for 8 hours to prepare a Prussian blue cathode material for a sodium battery.

[0064] <Comparative Example 4>

[0065] The same procedure as in Comparative Example 1 was carried out, but the reaction was carried out in a reaction tank for 15 hours to prepare a Prussian blue cathode material for a sodium battery.

[0066] The amounts of the Prussian blue cathode materials prepared in Examples 2 to 4 were measured and are shown in Table 1 below, and the amounts of the Prussian blue cathode materials prepared in Comparative Examples 1 to 4 were measured and are shown in Table 2 below.

[0067] (However, in the case of the Taylor reactor experiment, sampling was continued after 4 tons, as it was determined that the samples had stabilized due to their characteristics.)

[0068] [Table 1]

[0069] [Table 2]

[0070] As shown in Tables 1 and 2, the Prussian blue cathode materials prepared in Examples 2 to 4 of the present invention exhibited yields 1.2 to 1.95 times higher than those of the Prussian blue cathode materials prepared in Comparative Examples 1 to 4.

[0071] In addition, the Prussian blue cathode materials prepared in Examples 1 to 4 were photographed by SEM and shown in FIG. 3 below, and the Prussian blue cathode materials prepared in Comparative Examples 1 to 4 were photographed and shown in FIG. 4 below.

[0072] As shown in Figures 3 and 4 below, in the case of the Prussian blue cathode materials prepared in Examples 1 to 4 of the present invention, the particle surfaces become cleaner as they enter a normal state compared to the Prussian blue cathode materials prepared in Comparative Examples 1 to 4.

[0073] Meanwhile, in the case of the Prussian blue cathode materials prepared in Comparative Examples 1 to 4, it can be seen that the particle surfaces become smoother as the reaction time increases.

[0074] In addition, the average particle size of the Prussian blue cathode materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 was measured and is shown in Table 3 below.

[0075] [Table 3]

[0076] As shown in Table 3, in both Examples 1 to 4 and Comparative Examples 1 to 4, as the reaction time or residence time (τ) increases, the particle size also increases. This indicates that the particle size of the Prussian blue cathode materials prepared in Examples 1 to 4 is larger.

[0077] In addition, the XRD patterns of the Prussian blue cathode materials prepared in Examples 1 to 4 are shown in FIG. 5, and the XRD patterns of the Prussian blue cathode materials prepared in Comparative Examples 1 to 4 are measured and shown in FIG. 6 below. Examples 1 to 4 and Comparative Examples 1 to 4 are compared and shown in FIG. 7 below.

[0078] As shown in Figures 5 and 6 below, the XRD results show that there are double peaks at around 25 degrees, 40 degrees, 50 degrees, and 55 degrees, indicating that there is a high sodium content. Research has shown that a high sodium content has a positive effect on battery performance and capacity, so the more sodium a powder contains, the better its quality.

[0079] In addition, as shown in Figure 7 below, the higher the sodium content, the wider the lattice spacing within the structure, which is why the XRD peak at around 17 degrees shifts to the left. Comparing Comparative Example 1 (1 h) and Comparative Example 2 (4 h), the peak shifts to the right, and as the reaction time increases, the peak shifts to the left.

[0080] On the other hand, when Example 1 (1τ) is compared with Example 2 (4τ), it is seen that the signal moves to the right, and then, when it reaches a stable state, it moves to the left again.

[0081] In addition, the XRD patterns of the Prussian blue cathode materials prepared in Example 4 and Comparative Example 4 were measured and are shown in FIG. 8 below.

[0082] As shown in FIG. 8 below, the XRD result of the Prussian blue cathode material prepared in Example 4 is shifted more to the left, indicating better quality.

[0083] In addition, the charge / discharge capacities of the Prussian blue cathode materials prepared in Examples 1, 3, and 4 and Comparative Examples 1 to 3 were measured and are shown in Table 4 and FIG.

[0084] [Table 4]

[0085] As shown in Table 4 above and FIG. 9 below, in the comparative example, the charge / discharge capacity increases as the reaction time (h) increases, while in the example, the charge / discharge capacity increases and stabilizes as the residence time (τ) increases.

[0086] In addition, the test results of the charge / discharge capacity of the Prussian blue cathode materials prepared in Examples 1, 3, 4 and Comparative Examples 1 to 3 are shown in FIG.

[0087] As shown in FIG. 10 below, the results of Comparative Example 3 and Example 4 were almost identical, which indicates that the time required for Example 4 of the present invention using a Taylor reactor was further reduced.

[0088] In addition, the capacity retention rates of the Prussian blue cathode materials prepared in Examples 1, 3, and 4 and Comparative Examples 1 to 3 were measured and are shown in Table 5 and FIG.

[0089] (However, the capacity retention rate was calculated by comparing the trend of coulomb efficiency (200 cycles).)

[0090] [Table 5]

[0091] As shown in Table 5 above and FIG. 11 below, it can be seen that in both the Examples and Comparative Examples, the capacity retention rate improves with an increase in the reaction time (h) and residence time (τ), and it can be seen that Examples 1, 3, and 4 had a shorter reaction time and an increased capacity retention rate compared to Comparative Examples 1 to 3.

[0092] Therefore, the method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor according to the present invention provides a Prussian blue cathode material that exhibits excellent production efficiency for the Prussian blue cathode material and can produce a sodium battery with improved charge / discharge efficiency and capacity retention.

Claims

1. a first mixture preparation step of preparing a first mixture containing an aqueous iron chloride solution; a second mixture preparation step of preparing a second mixture containing an aqueous sodium ferrocyanide solution; a synthesis step of synthesizing a Prussian blue analog by introducing the mixture prepared in the first mixture preparation step and the mixture prepared in the second mixture preparation step into a Taylor reactor and reacting them under nitrogen injection conditions; an aging step of aging the Prussian blue analogue prepared through the synthesis step; a washing and filtering step of washing and filtering the Prussian blue analogue aged through the aging step with a detergent; and drying the Prussian blue analogue washed and filtered through the washing and filtering steps; A method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor, comprising:

2. 2. The method for manufacturing a Prussian blue cathode material for a sodium battery using a Taylor reactor according to claim 1, wherein the first mixture preparation step is performed by mixing 0.001M to 4M trisodium citrate with 0.001M to 6M aqueous iron chloride solution containing distilled water purged with nitrogen.

3. 2. The method for manufacturing a Prussian blue cathode material for a sodium battery using a Taylor reactor according to claim 1, wherein the second mixture is prepared by mixing 0.001M to 4M trisodium citrate with 0.001M to 1M aqueous sodium ferrocyanide solution containing nitrogen-purged distilled water.

4. 2. The method of claim 1, wherein the synthesizing step is performed by adding 100 parts by weight of the mixture prepared in the first mixture preparing step and 80 to 120 parts by weight of the mixture prepared in the second mixture preparing step to the Taylor reactor and stirring the mixture at a temperature of 10 to 100° C. and a speed of 50 to 1500 rpm for 1 to 1440 minutes.

5. 2. The method for preparing a Prussian blue cathode material for a sodium battery using a Taylor reactor according to claim 1, wherein the drying step is performed at a temperature of 40 to 130° C. for 10 to 30 hours.

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