阅读说明：本技术 一种铁基普鲁士蓝、制备方法及其应用 (Iron-based Prussian blue, preparation method and application thereof ) 是由 黄云辉 万忞 于 2021-06-21 设计创作，主要内容包括：本发明公开了一种铁基普鲁士蓝、制备方法及其应用,所述方法包括下列步骤：(1)将含有亚铁氰离子的盐溶解到去离子水溶液中,得到第一盐溶液,该第一盐溶液中亚铁氰离子的含量超过通过铁基普鲁士蓝所需化学计量比计算得到的亚铁氰离子的含量；(2)将含有亚铁离子或锰离子的盐溶解到去离子水溶液中,并加入柠檬酸三钠,得到第二盐溶液；(3)将第一盐溶液倒入第二盐溶液中,搅拌后静置,得到沉淀物,将该沉淀物清洗、干燥后得到铁基普鲁士蓝。本发明通过在前驱体溶液中引入大量Na～(+)和Fe(CN)-6～(4-),减少共沉淀法得到的产物中容易出现的[Fe(CN)-6]～(4-)空位缺陷和配位水,制备过程简单,解决铁基普鲁士蓝合成条件苛刻、产物中钠含量低,容量低等技术问题。(The invention discloses iron-based Prussian blue, a preparation method and application thereof, wherein the method comprises the following steps: (1) dissolving salt containing ferrocyanide ions into a deionized water solution to obtain a first salt solution, wherein the content of the ferrocyanide ions in the first salt solution exceeds the content of the ferrocyanide ions calculated by the stoichiometric ratio required by the iron-based Prussian blue; (2) dissolving a salt containing ferrous ions or manganese ions into a deionized water solution, and adding trisodium citrate to obtain a second salt solution; (3) and pouring the first salt solution into the second salt solution, stirring, standing to obtain a precipitate, and cleaning and drying the precipitate to obtain the iron-based Prussian blue. The invention introduces a large amount of Na into the precursor solution + And Fe (CN) 6 4‑ The method of reducing the value of a [ 2 ], [ alpha ] or a mixture thereof, which is easily occurring in a product obtained by coprecipitationFe(CN) 6 ] 4‑ Vacancy defects and coordinated water, the preparation process is simple, and the technical problems of harsh synthesis conditions, low sodium content in the product, low capacity and the like of the iron-based Prussian blue are solved.)

1. A method for preparing iron-based Prussian blue, which is characterized by comprising the following steps:

(1) dissolving salt containing ferrocyanide ions into a deionized water solution to obtain a first salt solution, wherein the content of the ferrocyanide ions in the first salt solution exceeds the content of the ferrocyanide ions calculated by the stoichiometric ratio required by the iron-based Prussian blue;

(2) dissolving a salt containing ferrous ions or manganese ions into a deionized water solution, and adding trisodium citrate to obtain a second salt solution;

(3) and pouring the first salt solution into the second salt solution, stirring, standing to obtain a precipitate, and cleaning and drying the precipitate to obtain the iron-based Prussian blue.

2. The method according to claim 1, wherein the salt containing ferrocyanide ions is sodium ferrocyanide or potassium ferrocyanide.

3. The method of claim 1 or 2, wherein the first salt solution is a near-saturated solution having a concentration of 0.62 to 1.03 moles/liter.

4. The method of claim 1, wherein 2.5 g trisodium citrate is added per 1 millimole of the salt containing ferrous or manganese ions in the second salt solution.

5. The method according to claim 1, wherein the stirring is followed by a standing step, in which the stirring is continued at a temperature of 40-50 ℃ and a rotation speed of 800-1000 rpm for 0.5-1 hour, and then the stirring is continued at a temperature of 20-28 ℃ for 24-30 hours.

6. The method according to claim 1, wherein the washing and drying of the precipitate are specifically: washing the precipitate with deionized water for at least 3 times, washing with anhydrous ethanol for at least 3 times, and drying the washed precipitate at 80-120 deg.C for 20-24 hr.

7. An iron-based prussian blue prepared by the preparation method of any one of claims 1 to 6.

8. The iron-based prussian blue as claimed in claim 7, wherein the iron-based prussian blue has a particle size of 300nm to 2 μm.

9. The use of the iron-based prussian blue according to claim 7 or 8, wherein the iron-based prussian blue is used as a positive electrode material of a sodium ion battery.

Technical Field

The invention belongs to the field of iron-based Prussian blue, and particularly relates to iron-based Prussian blue, a preparation method and application thereof.

Background

The synthesis method of the iron-based Prussian blue and the analogues thereof mainly focuses on a single iron source hydrothermal method and a double iron source coprecipitation method which take water as a solvent: (1) single iron source solution processMainly of Na₄Fe(CN)₆Dissolving in deionized water to form Na₄Fe(CN)₆And (3) adjusting the pH value of the aqueous solution by using weak acid, transferring the aqueous solution into a high-pressure reaction kettle, and carrying out hydrothermal reaction for 20 hours at the temperature of 140 ℃. In 2015, John B.Goodenough synthesized crystals of Federan Prussian blue analog using a single iron source hydrothermal method (L.Wang, J.Song, R.Qiao, L.A.Wray, M.A.Hossain, Y.D.Chuang, W.Yang, Y.Lu, D.Evans, J.J.Lee, S.Val, X.ZHao, M.Nishijima, S.Kakimoto and J.B.Goodenough, Rhombohedral Prussian White as catalyst for Rechargeable SodiumIon Batteries, Journal of the American Chemical Society,2015,137, 2548-; (2) the typical synthetic process is to use FeSO according to stoichiometric ratio₄(or other ferrous salts) and Na₄Fe(CN)₆As a precursor, respectively forming FeSO₄And Na₄Fe(CN)₆In aqueous solution, by dissolving Na₄Fe(CN)₆Solution with FeSO₄Mixing the solutions, carrying out coprecipitation reaction, washing the obtained precipitate with deionized water and ethanol, and centrifuging and collecting.

In the method, the product generated by a single iron source solution method has larger particle size, high quality, low yield and longer reaction time, and is easy to release toxic substances; the yield of the bi-iron source coprecipitation method is high, but when the obtained product is used as a sodium storage anode material, the actual specific capacity provided by the bi-iron source coprecipitation method is often far lower than the theoretical specific capacity, and particularly the high-potential capacity is poor in exertion, so that the specific energy of the electrode material is insufficient, and the practical large-scale application of the material is severely restricted. Therefore, the search for a simple method for preparing high-energy iron-based prussian blue analogue at low cost has great value for the practical application of the compound.

Disclosure of Invention

In view of the above-mentioned drawbacks or needs for improvement of the prior art, the present invention provides an iron-based prussian blue, a preparation method and applications thereof, which aim to improve the stability of prussian blue by introducing a large amount of Na into a precursor solution⁺And Fe (CN)₆ ⁴Reduction of [ Fe (CN) ] which is liable to appear in the product obtained by coprecipitation₆]⁴Vacancy defect and coordinated water, the preparation process is simple, the cost is low, and the technical problems of harsh synthesis conditions, low sodium content in the product, low capacity and the like of the iron-based Prussian blue are solved.

To achieve the above objects, according to one aspect of the present invention, there is provided a method for preparing iron-based prussian blue, the method comprising the steps of:

(1) dissolving salt containing ferrocyanide ions into a deionized water solution to obtain a first salt solution, wherein the content of the ferrocyanide ions in the first salt solution exceeds the content of the ferrocyanide ions calculated by the stoichiometric ratio required by the iron-based Prussian blue;

(2) dissolving a salt containing ferrous ions or manganese ions into a deionized water solution, and adding trisodium citrate to obtain a second salt solution;

(3) and pouring the first salt solution into the second salt solution, stirring, standing to obtain a precipitate, and cleaning and drying the precipitate to obtain the iron-based Prussian blue.

Preferably, the salt containing ferrocyanide ions is sodium ferrocyanide or potassium ferrocyanide.

Preferably, the first salt solution is a near saturated solution with a concentration of 0.62-1.03 mol/l.

Preferably, 2.5 g trisodium citrate is added per 1 millimole of salt containing ferrous or manganese ions in the second salt solution.

Preferably, the stirring is followed by standing, specifically, stirring is continued for 0.5-1 hour at a temperature of 40-50 ℃ and a rotation speed of 800-1000 rpm, and then standing is continued for 24-30 hours at a temperature of 20-28 ℃.

Preferably, the washing and drying of the precipitate are specifically as follows: washing the precipitate with deionized water for at least 3 times, washing with anhydrous ethanol for at least 3 times, and drying the washed precipitate at 80-120 deg.C for 20-24 hr.

According to another aspect of the present invention, there is provided an iron-based prussian blue prepared by the preparation method described above.

Preferably, the particle size of the iron-based prussian blue is 300nm-2 μm.

According to another aspect of the invention, the application of the iron-based Prussian blue as a positive electrode material of a sodium-ion battery is provided.

In general, at least the following advantages can be obtained by the above technical solution contemplated by the present invention compared to the prior art.

(1) The invention adopts the traditional ferrous sulfate or manganese sulfate and sodium ferrocyanide as iron sources for synthesizing the iron-based Prussian blue, and introduces a large amount of Na into a precursor solution of a dual-iron-source coprecipitation method⁺And Fe (CN)₆ ⁴And the structure of the nano iron-based Prussian blue particles is more complete. In particular, Fe (CN) in excess of the desired metering ratio₆ ⁴Can coordinate with the crystal lattice easily appearing vacancy while iron-based Prussian blue crystal nucleus grows in the coprecipitation process, reduces the generation of coordinated water, avoids the easily appearing vacancy defect in the crystal lattice, and in addition, can maintain sufficient Na in the preparation environment⁺The method is favorable for obtaining sodium-rich Prussian blue products, is favorable for improving the specific capacity and the first charging and discharging coulombic efficiency of the sodium-ion battery, and is an important technical index influencing the performance and industrialization of the sodium-ion full battery. Compared with the traditional single-iron source and double-iron source hydrosolvent coprecipitation method, the method has the advantages of safe and nontoxic production process, easily obtained raw materials, simple process, few product defects, high quality, low price, low equipment requirement and the like.

(2) The Prussian blue prepared by the method can be used as a sodium ion battery anode material, and compared with the Prussian blue anode material prepared by a traditional dual-iron source coprecipitation method, the sodium storage electrochemical performance, including the cycling stability and the charging and discharging specific capacity, of the Prussian blue anode material are greatly improved.

(3) In the present invention, it is preferable to use a nearly saturated salt solution containing ferrocyanide anion, and it is preferable to use the second salt solution in which 2.5 g of trisodium citrate is added per 1 mmol of salt containing ferrous ion or manganese ion, so that a high concentration of Na can be obtained⁺And Fe (CN)₆ ⁴Reaction environment, before implementationThe coprecipitation method is regulated and controlled by terminal ions, so that high Na in Prussian blue can be ensured⁺The content of water in the product is reduced.

Drawings

Fig. 1 is an XRD graph of iron-based prussian blue in example 1 of the present invention;

FIG. 2 is a SEM image of Fe-based Prussian blue in example 1 of the present invention;

fig. 3 is a charge/discharge curve of a sodium ion battery in which iron-based prussian blue is used as a positive electrode in example 1 of the present invention.

Fig. 4 is a graph showing cycle performance of a sodium ion battery in which iron-based prussian blue was used as a positive electrode in example 1 of the present invention.

Fig. 5 is an XRD chart of iron-based prussian blue in example 2 of the present invention.

FIG. 6 is a SEM image of Fe-based Prussian blue in example 2 of the present invention;

fig. 7 is a charge/discharge curve of a sodium ion battery in which iron-based prussian blue is used as a positive electrode in example 2 of the present invention.

Fig. 8 is a charge and discharge curve of a sodium ion battery in which iron-based prussian blue is used as a positive electrode in comparative example 1 of the present invention.

Fig. 9 is a charge and discharge curve of a sodium ion battery in which iron-based prussian blue is used as a positive electrode in comparative example 2 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Example 1

The embodiment provides a preparation method of iron-based prussian blue, the iron-based prussian blue prepared by the preparation method, and a sodium-ion battery cathode material using the iron-based prussian blue. The method comprises the following steps:

s1 sodium ferrocyanide powder with purity of more than 99.5 percent, 48.4 g, is added into 100 ml of deionized water and stirred at the temperature of 40 ℃ until a nearly saturated sodium ferrocyanide yellow solution 1 is formed;

s2, adding 0.556 g of ferrous sulfate powder with the purity of more than 99.5 percent and 5 g of trisodium citrate into 100 ml of deionized water, and stirring until a clear solution 2 is formed;

s3, directly pouring the solution 1 obtained in the step into the solution 2, continuously stirring the mixed solution for 0.5 hour, and then standing for 24 hours at the temperature of 25 ℃ to obtain light blue precipitate;

s4, collecting the blue precipitate obtained in the step S3 by centrifugation, and washing 3 times by deionized water and absolute ethyl alcohol respectively;

s5, carrying out vacuum drying on the centrifugal product obtained in the step S4, wherein the drying temperature is 120 ℃, the drying time is 20 hours, and cooling to room temperature to obtain the iron-based Prussian blue particles.

Fig. 1 is an XRD diffraction pattern of the iron-based prussian blue particles prepared in this example, and it can be seen that the synthesized powder is a pure phase by comparing with an XRD standard PDF card (i.e., JCPDS nos. 01-0239 shown in the lower part of fig. 1). FIG. 2 is a SEM image of the Fe-based Prussian blue particles prepared in the example, and it can be seen that the prepared powder is mainly nanoparticles with a particle size of 300-500 nm. The Prussian blue chemical expression obtained by combining element analysis and inductively coupled plasma spectral analysis calculation is as follows: na (Na)_1.95Fe[Fe(CN)₆]_0.88。

Referring to fig. 3 to 4, the iron-based prussian blue prepared by the preparation method of the invention is used as a sodium ion battery anode material to assemble a sodium ion battery, the charge-discharge current density in the experiment of the charge-discharge curve of the sodium ion battery is 170mA/g, the sodium ion battery shows very high specific capacity, the first discharge specific capacity reaches 156.2mAh/g, and simultaneously the discharge working voltage exceeds 3.1V, so that the energy density is close to 500 Wh/kg. In addition, the electrode can still provide a specific discharge capacity of about 137mAh/g after 50 cycles.

Example 2

The embodiment provides a preparation method of iron-based prussian blue, the iron-based prussian blue prepared by the preparation method, and a sodium-ion battery cathode material using the iron-based prussian blue. The method comprises the following steps:

s1 sodium ferrocyanide powder with purity of more than 99.5 percent, 48.4 g, is added into 100 ml of deionized water and stirred at the temperature of 40 ℃ until a nearly saturated sodium ferrocyanide yellow solution 1 is formed;

s2, adding 0.446 g of manganese sulfate powder with the purity of more than 99.5 percent and 5 g of trisodium citrate into 100 ml of deionized water, and stirring until a clear solution 2 is formed;

s3, directly pouring the solution 1 obtained in the step into the solution 2, continuously stirring the mixed solution for 0.5 hour, and then standing for 24 hours at the temperature of 25 ℃ to obtain a white precipitate;

s4, collecting the blue precipitate obtained in the step S3 by centrifugation, and washing 3 times by deionized water and absolute ethyl alcohol respectively;

s5, carrying out vacuum drying on the centrifugal product obtained in the step S4, wherein the drying temperature is 120 ℃, the drying time is 20 hours, and cooling to room temperature to obtain the iron-based Prussian blue particles.

Fig. 5 is an XRD diffraction pattern of prussian blue particles prepared in this example, and it can be seen that the synthesized powder is a pure phase by comparing with an XRD standard PDF card (i.e., JCPDS nos. 01-0239 shown in the lower part of fig. 1). Fig. 6 is a scanning electron microscope SEM image of the iron-based prussian blue particles prepared in the example, and it can be seen that the prepared powder is mainly particles having a particle size of 1 to 2 μm.

Referring to fig. 7, the iron-based prussian blue prepared by the preparation method of the present invention is used as the positive electrode material of the sodium ion battery to assemble the sodium ion battery, the charge and discharge current density of the sodium ion battery in the experiment of the charge and discharge curve is 170mA/g, the charge and discharge current density is very high, the first charge specific capacity reaches 149.4mAh/g, and the discharge specific capacity is 143.6mAh/g, and in addition, it is noted that the discharge working voltage exceeds 3.35V due to the use of Mn ions, such that the energy density reaches 481.6 Wh/kg.

Comparative example 1

The iron-based Prussian blue is prepared by adopting a traditional double-iron-source coprecipitation method in the comparative example, and specifically comprises the following steps:

the method comprises the following steps:

s1, adding 1.94 g of sodium ferrocyanide powder with the purity of more than 99.5 percent into 200 ml of deionized water according to the stoichiometric ratio, and stirring until a sodium ferrocyanide solution 1 is formed;

s2, adding 1.67 g of ferrous sulfate powder with the purity of more than 99.5 percent into 200 ml of deionized water according to the stoichiometric ratio, and stirring to form a clear solution 2;

s3, directly pouring the solution 1 obtained in the step into the solution 2, continuously stirring the mixed solution for 0.5 hour, and then standing for 6 hours at the temperature of 25 ℃ to obtain light blue precipitate;

s4, collecting the blue precipitate obtained in the step S3 by centrifugation, and washing 3 times by deionized water and absolute ethyl alcohol respectively;

s5, carrying out vacuum drying on the centrifugal product obtained in the step S4, wherein the drying temperature is 70 ℃, the drying time is 12 hours, and cooling to room temperature to obtain the iron-based Prussian blue particles.

As shown in figure 8, the iron-based Prussian blue prepared by the method is used as a positive electrode material of a sodium ion battery to assemble the sodium ion battery, the charge-discharge current density of the sodium ion battery in a charge-discharge curve experiment is 25mA/g, the first charge specific capacity is 127.9mAh/g, and the discharge specific capacity is 117.8 mAh/g.

Compared with the traditional method for preparing the iron-based Prussian blue by adopting the dual-iron-source co-precipitation method, the iron-based Prussian blue prepared by the preparation method provided by the invention has more excellent sodium storage electrochemical performance when being used as a positive electrode material of a sodium ion battery.

Example 3

The embodiment provides a preparation method of iron-based prussian blue, the iron-based prussian blue prepared by the preparation method, and a sodium-ion battery cathode material using the iron-based prussian blue. The method comprises the following steps:

s1 adding 30 g of sodium ferrocyanide powder with the purity of more than 99.5 percent into 100 ml of deionized water, and stirring at the temperature of 40 ℃ until a nearly saturated yellow solution 1 of sodium ferrocyanide is formed; the salt solution 1 is a nearly saturated solution with the concentration of 0.62 mol/L;

s2, adding 0.556 g of ferrous sulfate powder with the purity of more than 99.5 percent and 5 g of trisodium citrate into 100 ml of deionized water, and stirring until a clear solution 2 is formed;

s3, directly pouring the solution 1 obtained in the step into the solution 2, continuously stirring the mixed solution for 0.5 hour, and then standing for 24 hours at the temperature of 25 ℃ to obtain light blue precipitate;

s4, collecting the blue precipitate obtained in the step S3 by centrifugation, and washing 3 times by deionized water and absolute ethyl alcohol respectively;

s5, carrying out vacuum drying on the centrifugal product obtained in the step S4, wherein the drying temperature is 120 ℃, the drying time is 20 hours, and cooling to room temperature to obtain the iron-based Prussian blue particles.

Example 4

The embodiment provides a preparation method of iron-based prussian blue, the iron-based prussian blue prepared by the preparation method, and a sodium-ion battery cathode material using the iron-based prussian blue. The method comprises the following steps:

s1 adding 50 g of sodium ferrocyanide powder with the purity of more than 99.5 percent into 100 ml of deionized water, and stirring at the temperature of 40 ℃ until a nearly saturated yellow solution 1 of sodium ferrocyanide is formed; the salt solution 1 is a nearly saturated solution with the concentration of 1.03 mol/L;

s2, adding 0.556 g of ferrous sulfate powder with the purity of more than 99.5 percent and 5 g of trisodium citrate into 100 ml of deionized water, and stirring until a clear solution 2 is formed;

s3, directly pouring the solution 1 obtained in the step into the solution 2, continuously stirring the mixed solution for 0.5 hour, and then standing for 24 hours at the temperature of 25 ℃ to obtain light blue precipitate;

s4, collecting the blue precipitate obtained in the step S3 by centrifugation, and washing 3 times by deionized water and absolute ethyl alcohol respectively;

s5, carrying out vacuum drying on the centrifugal product obtained in the step S4, wherein the drying temperature is 120 ℃, the drying time is 20 hours, and cooling to room temperature to obtain the iron-based Prussian blue particles.

Comparative example 2

The method for preparing the iron-based Prussian blue by adopting the low-concentration sodium ferrocyanide, the iron-based Prussian blue prepared by the preparation method and the iron-based Prussian blue serving as the positive electrode material of the sodium-ion battery are adopted in the comparative example. The method comprises the following steps:

s1 adding 15 g of sodium ferrocyanide powder with the purity of more than 99.5% into 100 ml of deionized water, and stirring at 25 ℃ until a nearly saturated yellow solution 1 of sodium ferrocyanide is formed; the salt solution 1 is at a concentration of 0.31 mol/l;

s2, adding 0.556 g of ferrous sulfate powder with the purity of more than 99.5 percent and 5 g of trisodium citrate into 100 ml of deionized water, and stirring until a clear solution 2 is formed;

s3, directly pouring the solution 1 obtained in the step into the solution 2, continuously stirring the mixed solution for 0.5 hour, and then standing for 24 hours at the temperature of 25 ℃ to obtain light blue precipitate;

s4, collecting the blue precipitate obtained in the step S3 by centrifugation, and washing 3 times by deionized water and absolute ethyl alcohol respectively;

s5, carrying out vacuum drying on the centrifugal product obtained in the step S4, wherein the drying temperature is 120 ℃, the drying time is 20 hours, and cooling to room temperature to obtain the iron-based Prussian blue particles.

As shown in fig. 9, the iron-based prussian blue prepared by the method is used as a positive electrode material of a sodium ion battery to assemble the sodium ion battery, and in an experiment of a charge-discharge curve of the sodium ion battery, the charge-discharge current density is 170mA/g, the first charge specific capacity is 132.9mAh/g, and the discharge specific capacity is 142.3 mAh/g.

It can be seen that, compared with the conventional ferric source coprecipitation method for preparing iron-based prussian blue, the addition of the sodium ferrocyanide powder exceeding the stoichiometric ratio has more excellent sodium storage electrochemical performance when the prepared iron-based prussian blue is used as the positive electrode material of the sodium ion battery, but because the low-concentration sodium ferrocyanide is adopted in the comparative example 2, the specific first charge capacity is obviously smaller than that when the first salt solution is preferably adopted as a near-saturated solution with the concentration of 0.62-1.03 mol/l in the embodiment of the invention.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.