Method for preparing prussian blue positive electrode material for sodium battery using taylor reactor

Abstract

The present invention relates to a method for preparing a Prussian blue positive electrode material for a sodium battery using a Taylor reactor and, more specifically, the method comprises: a first mixture preparation step of preparing a first mixture mixed with an iron chloride aqueous solution; a second mixture preparation step of preparing a second mixture mixed with a sodium ferrocyanide aqueous 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 allowing them to undergo a reaction under nitrogen injection conditions; an aging step of aging the Prussian blue analog prepared in the synthesis step; a washing and filtration step of washing and filtering the Prussian blue analog aged in the aging step with a washing agent; and a drying step of drying the Prussian blue analog washed and filtered in the washing and filtration step. The method for manufacturing a Prussian blue positive electrode material for a sodium battery, consisting of the processes above, exhibits excellent production efficiency with respect to the Prussian blue positive electrode material, and provides the Prussian blue positive electrode material that provides a sodium battery with improved charge / discharge efficiency and capacity retention rate.

Description

Method for producing Prussian blue cathode material for sodium batteries using a Taylor reactor

[0001] The present invention relates to a method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor, and to a method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor, which exhibits excellent production efficiency for the Prussian blue cathode material and provides a sodium battery with improved charge / discharge efficiency and capacity retention rate.

[0002] Recently, the demand for secondary batteries has been increasing significantly as a power source for personal portable devices such as cell phones and tablet PCs, as well as for machines such as hybrid electric vehicles and plug-in electric vehicles.

[0003] In the past, lithium secondary batteries were most commonly applied as power supplies for machines such as personal mobile terminals and electric vehicles, but since lithium secondary batteries (lithium secondary cells) use a lot of rare metals such as cobalt (Co), nickel (Ni), manganese (Mn), and lithium (Li), there was a problem that the supply of rare metals was not smooth due to the increase in demand for large secondary batteries.

[0004] In order to solve the above problems and lower the manufacturing cost of secondary batteries, development is underway on sodium secondary batteries that are about 1 / 6 cheaper than lithium secondary batteries. Sodium secondary batteries can be made of materials that are abundant and inexpensive, and it is expected that commercialization of these will enable a large-scale supply of secondary batteries.

[0005] A sodium secondary battery is a secondary battery that contains an electrolyte. It is composed of a positive electrode and a negative electrode, which each contain a positive electrode active material and a negative electrode active material that can charge and discharge sodium (Na) ions, respectively, and an electrolyte containing sodium ions. In such a sodium secondary battery, charging and discharging occur as sodium ions move 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 occurs when sodium ions are doped into the negative electrode active material, and discharging occurs when sodium ions are removed from the negative electrode active material.

[0006] Recently, attempts have been made to apply Prussian blue, which exhibits excellent cycle life, low cost, and high speed, as a cathode active material for these sodium secondary batteries. Conventionally, a method using a stirring tank has been used in the process of manufacturing Prussian blue.

[0007] However, the conventional manufacturing method using a stirring tank had the problem of low productivity of Prussian blue and low charge / discharge effect and capacity retention rate of the manufactured Prussian blue.

[0008] The technology underlying the present invention is disclosed in Korean Patent Registration No. 10-2266574 (June 14, 2021) and Korean Patent Registration No. 10-2406480 (June 2, 2022).

[0009] The purpose 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 can provide a sodium battery with excellent production efficiency for the Prussian blue cathode material and improved charge / discharge efficiency and capacity retention rate.

[0010] The object of the present invention is achieved by providing a method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor, characterized in that it comprises a first mixture producing step of producing a first mixture mixed with an aqueous solution of iron chloride, a second mixture producing step of producing a second mixture mixed with an aqueous solution of sodium ferrocyanide, a synthesis step of introducing the mixture produced through the first mixture producing step and the mixture produced through the second mixture producing step into a Taylor reactor and reacting them under nitrogen injection conditions to synthesize a Prussian blue analogue, a maturation step of maturating the Prussian blue analogue produced through the synthesis step, a washing and filtration step of washing and filtering the Prussian blue analogue aged through the maturation step with a detergent, and a drying step of drying the Prussian blue analogue washed and filtered through the washing and filtration step.

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

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

[0013] According to a more preferred feature of the present invention, the synthesis step is performed by introducing 100 parts by weight of the mixture prepared through the first mixture preparation step and 80 to 120 parts by weight of the mixture prepared through the second mixture preparation step into 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 performed at a temperature of 40 to 130°C for 10 to 30 hours.

[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 exhibits an excellent effect of providing a Prussian blue cathode material capable of producing a sodium battery with improved charge / discharge efficiency and capacity retention rate.

[0016] Figure 1 is a flow chart showing 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 is a schematic diagram showing the reaction process of a Prussian blue analogue that proceeds in the synthesis step of the present invention.

[0018] Figure 3 is a photograph showing a Prussian blue cathode material manufactured through Examples 1 to 4 of the present invention, taken using SEM.

[0019] Figure 4 is a photograph showing the Prussian blue cathode material manufactured through comparative examples 1 to 4 of the present invention, taken using SEM.

[0020] Figures 5 to 8 are graphs showing the XRD trends of Prussian blue cathode materials manufactured through Examples 1 to 4 and Comparative Examples 1 to 4 of the present invention.

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

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

[0023] Figure 11 is a graph showing the capacity retention rate of Prussian blue cathode materials manufactured through Example 1, Examples 3 to 4, and Comparative Examples 1 to 3 of the present invention.

[0024] Hereinafter, preferred embodiments of the present invention and the properties of each component will be described in detail. However, this is intended to be a detailed description to enable a person having ordinary knowledge in the technical field to which the present invention pertains to easily carry out the invention, and does not mean that the technical idea and scope of the present invention are limited thereby.

[0025]

[0026] The method for manufacturing a Prussian blue cathode material for a sodium battery using a Taylor reactor according to the present invention comprises a first mixture manufacturing step (S101) of manufacturing a first mixture mixed with an aqueous solution of iron chloride, a second mixture manufacturing step (S101-1) of manufacturing a second mixture mixed with an aqueous solution of sodium ferrocyanide, a synthesis step (S103) of introducing the mixture manufactured through the first mixture manufacturing step (S101) and the mixture manufactured through the second mixture manufacturing step (S101-2) into a Taylor reactor and reacting them under nitrogen injection conditions to synthesize a Prussian blue analogue, a maturation step (S105) of maturating the Prussian blue analogue manufactured through the synthesis step (S103), a washing and filtration step (S107) of washing and filtering the Prussian blue analogue aged through the maturation step (S105) with a detergent, and a washing and filtration step (S107) of synthesizing the Prussian blue analogue. It consists of a drying step (S109) for drying the Prussian blue analogue.

[0027]

[0028] The above first mixture preparation step (S101) is a step for preparing a first mixture mixed with an aqueous solution of iron chloride (FeCl2·4H2O), and is preferably performed by mixing trisodium citrate (Trisodium Citrate) and an aqueous solution of iron chloride to prepare the first mixture, and is more preferably performed by mixing 0.001 to 6 M of an aqueous solution of iron chloride containing distilled water purged with nitrogen into 0.001 to 4 M of trisodium citrate and stirring at a speed of 800 to 900 rpm.

[0029] At this time, it is more preferable that the distilled water purged with nitrogen is produced by injecting nitrogen into the distilled water at an amount of 18 to 22 cc / min.

[0030]

[0031] The second mixture preparation step (S101-1) is a step for preparing a second mixture in which a sodium ferrocyanide aqueous solution (Na4Fe(CN)6·10H2O) is mixed, and is preferably performed by mixing a sodium ferrocyanide aqueous solution containing trisodium citrate and distilled water purged with nitrogen to prepare the second mixture, and is more preferably performed by mixing a 0.001 to 1 M sodium ferrocyanide aqueous solution containing distilled water purged with nitrogen to 0.001 to 4 M sodium citrate and stirring at a speed of 800 to 900 rpm.

[0032] At this time, it is more preferable that the distilled water purged with nitrogen is produced by injecting nitrogen into the distilled water at an amount of 18 to 22 cc / min.

[0033]

[0034] The above synthesis step (S103) is a step of synthesizing a Prussian blue analog by introducing the mixture manufactured through the first mixture manufacturing step (S101) and the mixture manufactured through the second mixture manufacturing step (S101-1) into a Taylor reactor and reacting them under nitrogen injection conditions. It is preferable that 100 parts by weight of the mixture manufactured through the first mixture manufacturing step (S101) and 80 to 120 parts by weight of the mixture manufactured through the second mixture manufacturing step (S101-1) be introduced into a Taylor reactor and stirred at a temperature of 10 to 100°C and a speed of 50 to 1500 rpm for 10 to 1200 minutes.

[0035] A Prussian blue analogue is synthesized through the above synthesis step (S103). At this time, it is more preferable that the nitrogen injection be performed at a condition of 18 to 22 cc / min.

[0036] The reaction process of the Prussian blue analogue that is carried out in the above synthesis step (S101) is carried out by the coprecipitation method, and the reaction process of the Prussian blue analogue that is carried out by the coprecipitation method is shown in the reaction scheme 1 and Figure 2 below.

[0037] <Reaction Scheme 1>

[0038] [Fe(CN)6 4- ]→[Fe(CN)6 4- ]+Fe 2+ +[CN]-xNA+Fe(CN)6 4- +Fe 2+ / 3+ →NaxFe[Fe(CN)6]

[0039] The synthesis step of the present invention proceeds as shown in the above reaction scheme 1 by reacting a first mixture containing iron ions and a second mixture containing ferrocyanide to synthesize a final product, a Prussian blue analogue (NaxFe2(CN)6).

[0040] Co-precipitation refers to the phenomenon in which a substance precipitates together with another substance when precipitating. It is a method in which several different ions precipitate together in an aqueous or non-aqueous solution, and is the most commonly used method for manufacturing precursors.

[0041]

[0042] The maturation step (S105) is a step for maturing the Prussian blue analogue synthesized through the synthesis step (S103), and is preferably performed by wrapping the Prussian blue analogue synthesized through the synthesis step (S103) in parafilm at room temperature without stirring or heating and maturating it in a desiccator for 22 to 26 hours.

[0043] By going through the maturation step (S105) performed through the above process, the performance of the synthesized Prussian blue cathode material can be improved.

[0044]

[0045] The above washing and filtration step (S107) is a step of washing and filtering the Prussian blue analogue matured through the maturation step (S105) with a detergent, and is preferably performed by washing 100 parts by weight of the Prussian blue analogue matured through the maturation step (S105) with 650 to 700 parts by weight of a detergent 2 to 3 times.

[0046] At this time, it is preferable that the detergent is made by mixing 1 to 1.5 parts by weight of trisodium citrate with 100 parts by weight of distilled water, and after the washing is completed, it is preferable to carry out a process of filtration using a centrifuge or a continuous centrifuge and an SS filter device.

[0047]

[0048] The above drying step (S109) is a step of drying the Prussian blue analogue washed and filtered through the washing and filtration step (S107), and it is preferable that the Prussian blue analogue washed and filtered through the washing and filtration step (S107) be dried at a temperature of 40 to 130°C for 10 to 30 hours.

[0049] At this time, the device used for drying is not particularly limited and various equipment can be used, but a vacuum oven or continuous dryer can be applied. When drying a small amount, it is efficient to use a vacuum oven, and when drying a large amount, it is preferable to apply a continuous dryer.

[0050]

[0051] Hereinafter, a method for manufacturing a Prussian blue cathode material for a sodium battery using a Taylor reactor according to the present invention and the properties of a Prussian blue cathode material for a sodium battery manufactured by the method will be described with examples.

[0052]

[0053] <Manufacturing Example 1> Manufacturing of the first mixture

[0054] A first mixture was prepared by mixing 3M of an aqueous solution of iron chloride containing distilled water purged with nitrogen (20 cc / min) with 2M of sodium citrate and stirring at a speed of 850 rpm.

[0055]

[0056] <Manufacturing Example 2> Manufacturing of the second mixture

[0057] A second mixture was prepared by mixing 0.5 M of sodium ferrocyanide aqueous solution containing distilled water purged with nitrogen (20 cc / min) with 2 M of sodium citrate trisodium and stirring at a speed of 850 rpm.

[0058]

[0059] <Comparative Manufacturing Example 1> Manufacturing of the Second Mixture

[0060] A second mixture was prepared by mixing 2 M sodium citrate trisodium and 0.5 M sodium ferrocyanide aqueous solution and stirring at a speed of 850 rpm.

[0061]

[0062] <Example 1>

[0063] 100 parts by weight of the first mixture manufactured through the above Manufacturing Example 1 and 100 parts by weight of the second mixture manufactured through the above Manufacturing Example 2 were introduced into a Taylor reactor and stirred at a temperature of 80°C and a speed of 600 rpm for a residence time of 1τ under conditions of nitrogen purging (20 cc / min) to synthesize a Prussian blue analogue, and the synthesized Prussian blue analogue was wrapped with parafilm and aged in a desiccator for 24 hours, and the aged Prussian blue analogue was washed twice with a washing solution, and after being introduced into a centrifuge, centrifuged at a speed of 8500 rpm for 5 minutes and filtered, and the filtered Prussian blue analogue was introduced into a vacuum oven and dried at a temperature of 120°C for 24 hours to manufacture a Prussian blue cathode material for a sodium battery.

[0064]

[0065] <Example 2>

[0066] A Prussian blue cathode material for a sodium battery was manufactured in the same manner as in Example 1 above, but with a residence time of 4τ.

[0067]

[0068] <Example 3>

[0069] A Prussian blue cathode material for a sodium battery was manufactured in the same manner as in Example 1 above, but with a residence time of 5τ.

[0070]

[0071] <Example 4>

[0072] A Prussian blue cathode material for a sodium battery was manufactured in the same manner as in Example 1 above, but with a residence time of 6τ.

[0073]

[0074] <Comparative Example 1>

[0075] 100 parts by weight of the first mixture manufactured through the above Manufacturing Example 1 and 100 parts by weight of the second mixture manufactured through the above Comparative Manufacturing Example 1 were added to a reaction tank, and the mixture was reacted for 1 hour at a temperature of 80°C and a speed of 850 rpm under conditions of nitrogen purging (20 cc / min) to synthesize a Prussian blue analogue, and the synthesized Prussian blue analogue was wrapped with parafilm and aged in a desiccator for 24 hours, and the aged Prussian blue analogue was washed twice with a washing solution, and after being placed in a centrifuge, centrifuged at a speed of 8500 rpm for 5 minutes and filtered, and the filtered Prussian blue analogue was placed in a vacuum oven and dried at a temperature of 120°C for 24 hours to manufacture a Prussian blue cathode material for a sodium battery.

[0076]

[0077] <Comparative Example 2>

[0078] The same procedure as in Comparative Example 1 was followed, but the reaction was carried out in a reaction tank for 4 hours to manufacture a Prussian blue cathode material for a sodium battery.

[0079]

[0080] <Comparative Example 3>

[0081] The same procedure as in Comparative Example 1 was followed, but the reaction was carried out in a reaction tank for 8 hours to manufacture a Prussian blue cathode material for a sodium battery.

[0082]

[0083] <Comparative Example 4>

[0084] The same procedure as in Comparative Example 1 was followed, but the reaction was carried out in a reaction tank for 15 hours to manufacture a Prussian blue cathode material for a sodium battery.

[0085]

[0086] The amount of the Prussian blue cathode material manufactured through the above Examples 2 to 4 was measured and shown in Table 1 below, and the amount of the Prussian blue cathode material manufactured through the above Comparative Examples 1 to 4 was measured and shown in Table 2 below.

[0087] {However, in the case of the Taylor reactor experiment, sampling was conducted based on the judgment that samples after 4t were stabilized due to the nature of the experiment.}

[0088] Table 1

[0089]

[0090] Table 2

[0091]

[0092] As shown in Tables 1 to 2 above, it can be seen that the Prussian blue cathode material manufactured through Examples 2 to 4 of the present invention exhibits a yield that is 1.2 to 1.95 times higher than that of the Prussian blue cathode material manufactured through Comparative Examples 1 to 4.

[0093]

[0094] In addition, the Prussian blue cathode materials manufactured through Examples 1 to 4 were photographed using SEM and shown in Fig. 3 below, and the Prussian blue cathode materials manufactured through Comparative Examples 1 to 4 were photographed and shown in Fig. 4 below.

[0095] As shown in Figures 3 to 4 below, the Prussian blue cathode material manufactured through Examples 1 to 4 of the present invention enters a steady state, and thus, it can be seen that the surface of the particles becomes cleaner than that of the Prussian blue cathode material manufactured through Comparative Examples 1 to 4.

[0096] On the other hand, in the case of the Prussian blue cathode materials manufactured through Comparative Examples 1 to 4, it can be seen that the surface of the particles becomes smoother as the reaction time increases.

[0097]

[0098] In addition, the average particle size of the Prussian blue cathode materials manufactured through Examples 1 to 4 and Comparative Examples 1 to 4 was measured and shown in Table 3 below.

[0099] Table 3

[0100]

[0101] As shown in Table 3 above, it can be seen that in all of Examples 1 to 4 and Comparative Examples 1 to 4 of the present invention, as the reaction time or residence time (τ) increases, the particle size also increases, and it can be seen that the particle size of the Prussian blue cathode material manufactured through Examples 1 to 4 is larger.

[0102]

[0103] In addition, the XRD trends of the Prussian blue cathode materials manufactured through Examples 1 to 4 are shown in FIG. 5, the XRD trends of the Prussian blue cathode materials manufactured through Comparative Examples 1 to 4 are measured and shown in FIG. 6 below, and a comparison of Examples 1 to 4 and Comparative Examples 1 to 4 is shown in FIG. 7 below.

[0104] As shown in Figures 5 and 6 below, the XRD results show that there are double peaks around 25, 40, 50, and 55 degrees, indicating a high sodium content. Research has shown that a high sodium content has a positive effect on battery performance and capacity, suggesting that powders with a high sodium content are of better quality.

[0105] In addition, as shown in Figure 7 below, as the sodium content increases, the internal lattice spacing of the structure increases, and thus, according to the research results showing that the XRD peak around 17 degrees moves to the left, when comparing Comparative Example 1 (1 h) and Comparative Example 2 (4 h), it can be seen that it moves to the right and then moves to the left as the reaction time gradually increases.

[0106] On the other hand, when comparing Example 1 (1τ) and Example 2 (4τ), we can see that it moves to the right and then, when it reaches a stable state, moves to the left again.

[0107]

[0108] In addition, the XRD trends of the Prussian blue cathode material manufactured through the above Example 4 and Comparative Example 4 were measured and shown in Figure 8 below.

[0109] As shown in Figure 8 below, it can be seen that the XRD results of the Prussian blue cathode material manufactured through Example 4 are slightly more to the left, indicating that it exhibits better quality.

[0110]

[0111] In addition, the charge / discharge capacities of the Prussian blue cathode materials manufactured through the above-described Example 1, Examples 3 to 4, and Comparative Examples 1 to 3 were measured and shown in Table 4 and Figure 9 below.

[0112] Table 4

[0113]

[0114] As shown in Table 4 above and Figure 9 below, in the case of the comparative example, it can be seen that the charge / discharge capacity increases as the reaction time (h) increases, and in the case of the example, it can be seen that it increases and stabilizes and is maintained as the residence time (τ) increases.

[0115]

[0116] In addition, the results of the charge / discharge capacity test of the Prussian blue cathode material manufactured through the above-described Example 1, Examples 3 to 4, and Comparative Examples 1 to 3 are shown in Figure 10 below.

[0117] As shown in Figure 10 below, the results of Comparative Example 3 and Example 4 were found to be almost the same, which shows that the time of Example 4 of the present invention using a Taylor reactor is further shortened.

[0118]

[0119] In addition, the capacity retention rate of the Prussian blue cathode materials manufactured through the above-described Example 1, Examples 3 to 4, and Comparative Examples 1 to 3 was measured and shown in Table 5 and Figure 11 below.

[0120] {However, the capacity retention rate was measured using a method comparing the Coulomb efficiency (200 cycle) trend.}

[0121] Table 5

[0122]

[0123] As shown in Table 5 above and Figure 11 below, it can be seen that the capacity retention rate improves as the reaction time (h) and residence time (τ) increase in both the examples and comparative examples, and it can be seen that the reaction time is shortened and the capacity retention rate increases in Examples 1, 3 and 4 compared to Comparative Examples 1 and 3.

[0124]

[0125] Therefore, the method for manufacturing 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 provides a Prussian blue cathode material capable of manufacturing a sodium battery with improved charge / discharge efficiency and capacity retention rate.

Claims

1. A first mixture preparation step for preparing a first mixture mixed with an aqueous solution of iron chloride; A second mixture preparation step for preparing a second mixture mixed with a sodium ferrocyanide aqueous solution; A synthesis step of synthesizing a Prussian blue analogue by introducing a mixture manufactured through the first mixture manufacturing step and a mixture manufactured through the second mixture manufacturing step into a Taylor reactor and reacting them under nitrogen injection conditions; A maturing step for maturing the Prussian blue analogue manufactured through the above synthesis step; A washing and filtration step of washing and filtering the Prussian blue analogue matured through the above maturation step with a detergent; and A method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor, characterized in that the method comprises a drying step of drying a Prussian blue analogue washed and filtered through the washing and filtration step.

2. In claim 1, A method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor, characterized in that the first mixture preparation step is performed by mixing 0.001 to 6 M of an aqueous solution of iron chloride containing distilled water purged with nitrogen into 0.001 to 4 M of trisodium citrate.

3. In claim 1, A method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor, characterized in that the second mixture preparation step is performed by mixing 0.001 to 1 M of a sodium ferrocyanide aqueous solution containing distilled water purged with nitrogen into 0.001 to 4 M of trisodium citrate.

4. In claim 1, A method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor, characterized in that the synthesis step comprises introducing 100 parts by weight of a mixture produced through the first mixture production step and 80 to 120 parts by weight of a mixture produced through the second mixture production step into a 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. In claim 1, A method for producing a Prussian blue cathode material for a sodium battery using a Taylor reactor, characterized in that the drying step is performed at a temperature of 40 to 130°C for 10 to 30 hours.

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