Method for preparing Prussian blue and analogues by utilizing precipitation conversion reaction

Abstract

The invention relates to a method for preparing Prussian blue and analogues by utilizing a precipitation conversion reaction, which comprises the following steps: mixing ferricyanide, transition metal salt and a solvent at one time, generating a precipitate containing a target product through the precipitation conversion reaction, and washing and drying to obtain the Prussian blue and analogues.

Description

Technical Field

[0001] The invention relates to a method for preparing Prussian blue and the like by using precipitation conversion reaction and application thereof in a battery, belonging to the technical field of Prussian blue and the like. Background Art

[0002] Prussian blue and its analogs (PBAs) have a face-centered cubic structure with the general formula A x M[Fe(CN)6]·zH2O, where A represents a monovalent ion (such as Li + 、Na + , K + NH4 + The structure is characterized by the following: the transition metal ion M is connected to the N in -C≡N-, and the Fe is connected to the C in -C≡N-, forming a rigid open structure. The interstitial position in this open structure can accommodate a certain amount of monovalent ions (such as Li + 、Na + , K + NH4 + The PBAs can be divided into two categories according to the electrochemical active sites. One of them has only a single electrochemical active site. When M is Zn, Ni, or Cu, only Fe connected to C exists. 2+ / 3+ The other has two electrochemically active sites. When M is Mn, Fe, or Co, there is not only Fe connected to C but also Fe 2+ / 3+ There will also be Mn 2+ / 3+ , Fe 2+ / 3+ ,Co 3+ / 4+ The variable valence site. Generally speaking, in batteries, Prussian blue with a single electrochemically active site has better cycle stability when used as the positive or negative electrode of the battery. However, Prussian blue with a single electrochemically active site has poorer cycle stability when used as the positive or negative electrode of the battery. Prussian blue and its analogs have the advantages of low price and a wide range of optional elements, making it a hot spot in battery material research.

[0003] At present, aqueous phase coprecipitation method is generally used to synthesize PBAs (such as Chinese invention patents CN115023829A, CN115020701A, CN115557516A, etc.). The specific process of coprecipitation is to mix aqueous solution A containing ferrocyanide and aqueous solution B containing transition metal salt and complexing agent through a peristaltic pump. During the mixing process, a coprecipitation reaction of Prussian blue will occur. The disadvantage of this method is that the synthesis process is relatively complicated, involving the preparation of two solutions, the dripping of peristaltic pumps and the use of complexing agents. The use of peristaltic pumps is to control the macroscopic concentration of the reaction, and the use of complexing agents is to control the microscopic reaction concentration. The purpose of both steps is to avoid high reaction rates caused by high reaction concentrations, which affect the performance of Prussian blue. However, the preparation of two solutions and the slow dripping of peristaltic pumps will increase the production time of Prussian blue, and the use of complexing agents will increase the production cost of Prussian blue. Therefore, if there is a method to avoid the preparation of multiple solutions, the use of peristaltic pumps and complexing agents, it will be able to shorten its production time and reduce its production cost. 。 Summary of the invention

[0004] In view of the defects of the current PBA synthesis technology and the demand for improved performance of PBAs, the present invention provides a method for synthesizing Prussian blue and the like by using a precipitation conversion reaction and an application thereof in a battery.

[0005] On the one hand, the present invention provides a method for preparing Prussian blue and its analogues by precipitation conversion reaction, comprising: mixing ferrocyanide, a transition metal salt and a solvent at one time, first subjecting the mixture to a precipitation conversion reaction to generate a precipitate containing a target product, and then washing and drying the precipitate to obtain the Prussian blue and its analogues.

[0006] In this patent, Prussian blue is synthesized based on the transformation principle of precipitation, that is, using the difference in solubility of ferrocyanide, transition metal salt, alkali metal salt and Prussian blue and the like in solution. Taking the most common ferric iron-based Prussian blue as an example, the synthesis reaction equation using sodium ferrocyanide and ferrous chloride in ethylene glycol is as follows: In ethylene glycol: Na4Fe(CN)6↓+FeCl2↓→Na2FeFe(CN)6↓+2NaCl↓(1); Because the solubility of ferrocyanide or transition metal salt in ethylene glycol is very low during the precipitation conversion reaction to synthesize Prussian blue and the like, the reaction rate can be effectively controlled while eliminating the need for a peristaltic pump and a complexing agent. Therefore, the performance degradation of Prussian blue caused by a too fast precipitation reaction can be greatly avoided. At the same time, the synthesis method adopted can avoid the use of a large amount of solvents and complexing agents, which can greatly reduce the current cost of synthesizing Prussian blue.

[0007] Preferably, the ferrocyanide is at least one of sodium ferrocyanide, potassium ferrocyanide, ammonium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and ammonium ferrocyanide.

[0008] Preferably, the cation in the transition metal salt is at least one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and the anion is SO4 2- ,CO3 2- 、NO3 - , Cl - Br ─ At least one of the following: the molar ratio of the transition metal salt to ferrocyanide is (5-0.5):1.

[0009] Preferably, the solvent includes at least one of methanol, ethanol, ethylene glycol, isopropanol, glycerol, ether, propylene oxide, acetone, methyl butyl ketone, methyl isobutyl ketone, acetonitrile, trimethyl phosphate, triethyl phosphate, ethylene carbonate, propylene carbonate, dimethyl sulfoxide, sulfolane, methyl acetate, ethyl acetate, propyl acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, pyridine, phenol, and water; The ratio of the transition metal salt to the solvent is 1 mmoL: (0.1-20) mL.

[0010] Preferably, the reaction temperature is 0 to 200° C., and the reaction time is 1 to 72 hours; preferably, the reaction method is water bath, oil bath, solvent thermal, ball milling or microwave-assisted synthesis.

[0011] Preferably, the drying is vacuum drying, the vacuum drying temperature is 30°C to 200°C, the time is 2 to 48 hours, and the vacuum degree is <10 kPa.

[0012] In another aspect, the present invention provides Prussian blue and the like prepared according to the above method.

[0013] In another aspect, the present invention provides a use of Prussian blue and the like in a battery.

[0014] Preferably, the Prussian blue and the like are used as positive electrode materials or negative electrode materials.

[0015] Preferably, the battery includes a lithium ion battery, a sodium ion battery, a potassium ion battery, an ammonium ion battery, a zinc ion battery, a magnesium ion battery, or a calcium ion battery.

[0016] Beneficial effects of the present invention: (1) The modified method of the present invention for synthesizing Prussian blue and its analogs by precipitation conversion adopts the basic principle of precipitation conversion and uses very few solvents and steps to synthesize Prussian blue and its analogs. This method can produce Prussian blue in an efficient, simple and low-cost manner, avoids the use of complexing agents, and reduces the synthesis cost of Prussian blue; (2) The present invention adopts a one-step method to synthesize Prussian blue, avoiding the traditional preparation of multiple solutions and the slow dripping process of a peristaltic pump, simplifying the process flow, and reducing production equipment and personnel; (3) In the present invention, by selecting different solvents and controlling the reaction rate, the performance degradation in the one-step synthesis of Prussian blue caused by an excessively fast reaction rate can be greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The XRD patterns of Prussian blue and the like prepared in Example 1; Figure 2 The SEM images of Prussian blue and the like prepared in Example 1; Figure 3 TEM spectra of Prussian blue and the like prepared in Example 1; Figure 4 The constant current charge and discharge diagram of Prussian blue and the like prepared in Example 1; Figure 5 The cycle life graph of Prussian blue and the like prepared in Example 1; Figure 6 The XRD patterns of Prussian blue and the like prepared in Example 2; Figure 7 The SEM images of Prussian blue and the like prepared in Example 2; Figure 8 TEM spectra of Prussian blue and the like prepared in Example 2; Fig. 9 The constant current charge and discharge diagram of Prussian blue and the like prepared in Example 2; Fig.10 The cycle life graph of Prussian blue and the like prepared in Example 2; Fig.11 The XRD patterns of Prussian blue and the like prepared in Example 3; Fig.12 The SEM images of Prussian blue and the like prepared in Example 3; Fig.13 The XRD patterns of Prussian blue and the like prepared in Example 5; Fig.14 The SEM images of Prussian blue and the like prepared in Example 5; Fig.15XRD patterns of Prussian blue and the like prepared in Comparative Example 1; Fig.16 The SEM images of Prussian blue and the like prepared in Comparative Example 1; Fig.17 XRD patterns of Prussian blue and the like prepared in Comparative Example 2; Fig.18 The SEM images of Prussian blue and the like prepared in Comparative Example 2; Fig.19 XRD patterns of Prussian blue and the like prepared in Comparative Example 3; Fig. 20 This is the SEM spectrum of Prussian blue and its analogs prepared in Comparative Example 3. DETAILED DESCRIPTION

[0018] The present invention is further described below by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0019] In the present disclosure, based on the basic principle of precipitation conversion, PBAs can be synthesized with less solvent, avoiding the preparation of multiple solutions, the use of peristaltic pumps and complexing agents, greatly reducing the cost of synthesizing PBAs, and paving the way for the industrial production of high-performance Prussian blue.

[0020] In order to synthesize high-performance Prussian blue and the like at low cost, the present invention provides a synthesis method based on the precipitation conversion principle. The basic principle of the synthesis of the present invention is precipitation conversion reaction, and a one-time mixing method is adopted, which greatly reduces the steps of material synthesis, avoids the use of complexing agents, and reduces the synthesis cost of the material.

[0021] Ferrocyanide, transition metal salt, and solvent of appropriate proportion and type are selected as raw materials. Further, the ferrocyanide is one or more of sodium ferrocyanide, potassium ferrocyanide, ammonium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide, and ammonium ferrocyanide; the composition of the transition metal salt is as follows: the cation is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and the anion is SO4 2- ,CO3 2- 、NO3 - , Cl - Br -Further, the solvent in a suitable proportion may be one or more of: methanol, ethanol, ethylene glycol, isopropanol, glycerol, ether, propylene oxide, acetone, methyl butyl ketone, methyl isobutyl ketone, acetonitrile, trimethyl phosphate, triethyl phosphate, ethylene carbonate, propylene carbonate, dimethyl sulfoxide, sulfolane, methyl acetate, ethyl acetate, propyl acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, pyridine, phenol, water, etc. One or more mixed solvents.

[0022] All raw materials are mixed at once and placed under suitable conditions to synthesize Prussian blue and the like. Further, suitable conditions may be: water bath, oil bath, solvent heat, ball milling or microwave assisted synthesis. Further, all materials are mixed at once.

[0023] After washing the obtained product, it is dried under a certain vacuum degree and temperature to obtain the final product. Furthermore, the drying temperature is between 30°C and 200°C.

[0024] The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0025] Example 1: Preparation of Prussian Blue in Ethylene Glycol Step 1: Weigh 4 mmol Na4Fe(CN)6 (1.2156 g), 4 mmol FeCl2·4H2O (0.7952 g) and 45 ml ethylene glycol; Step 2: Mix the three raw materials at once, place in a 60°C water bath, and stir for 48 hours; Step 3: The above materials were washed with anhydrous ethanol and deionized water by centrifugation and dried under vacuum at 120°C for 24 hours to obtain the final product.

[0026] Example 2: Preparation of Prussian Blue in Ethylene Glycol Step 1: Weigh 4 mmol Na2Fe(CN)6 (1.2156 g), 4 mmol FeSO4·7H2O (1.1120 g) and 45 ml ethylene glycol; Step 2: Mix the above three raw materials at once, place in a 60°C water bath, and stir for 48 hours; Step 3: The above materials were washed with anhydrous ethanol and deionized water by centrifugation and dried under vacuum at 120°C for 24 hours to obtain the final product.

[0027] Example 3: Preparation of Prussian Blue in Dimethyl Sulfoxide Step 1: Weigh 2mmol Na2Fe(CN)6 (0.6078g), 2mmol MnCl2 (0.2516g) and 15ml dimethyl sulfoxide; Step 2: Mix the above three raw materials at once, stir for 48 hours, and keep warm at 60℃ for 24 hours; Step 3: The above materials were washed with anhydrous ethanol and deionized water by centrifugation and vacuum dried at 100°C for 24 hours to obtain the final product.

[0028] Example 4: Preparation of Prussian Blue in a Mixed Solution of Ethanol Step 1: Weigh 2mmol Na2Fe(CN)6 (0.6078g), 2mmol MnCl2 (0.2516g) and 15ml ethanol; Step 2: Mix the above three raw materials at once, stir for 48 hours, and keep warm at 60℃ for 24 hours; Step 3: The above materials were washed with anhydrous ethanol and deionized water by centrifugation and vacuum dried at 100°C for 24 hours to obtain the final product.

[0029] Example 5: One-step preparation of Prussian blue in aqueous solution Step 1: Weigh 2mmol Na2Fe(CN)6 (0.6078g), 2mmol MnCl2 (0.2516g) and 15ml deionized water; Step 2: Mix the above three raw materials at once, stir for 48 hours, and keep warm at 60℃ for 24 hours; Step 3: Wash the above materials with deionized water by centrifugation and dry them in vacuum at 100°C for 24 hours to obtain the final product.

[0030] Comparative Example 1: Prussian blue prepared by dropwise addition in aqueous solution Step 1: Weigh 2mmol Na2Fe(CN)6 (0.6078g) and dissolve it in 50ml deionized water, marked as solution A; weigh 2mmol MnCl2 (0.2516g) and dissolve it in 50ml deionized water, marked as solution B; Step 2: Add solution B dropwise to solution A at room temperature and stir for 6 hours; Step 3: Wash the above materials with deionized water by centrifugation and dry them in vacuum at 60°C for 18 hours to obtain the final product.

[0031] Comparative Example 2: Prussian blue prepared by dropwise addition in aqueous solution Step 1: Weigh 2mmol Na2Fe(CN)6 (0.6078g) and dissolve it in 50ml deionized water, marked as solution A; weigh 2mmol FeCl2 (0.2516g) and dissolve it in 50ml deionized water, marked as solution B; Step 2: Add solution B dropwise to solution A at room temperature and stir for 6 hours; Step 3: Wash the above materials with deionized water by centrifugation and dry them in vacuum at 60°C for 18 hours to obtain the final product.

[0032] Comparative Example 3: Prussian blue prepared by dropwise addition in aqueous solution Step 1: Weigh 2mmol Na2Fe(CN)6 (0.6078g) and dissolve it in 50ml deionized water, marked as solution A; weigh 2mmol FeSO4 (0.2516g) and dissolve it in 50ml deionized water, marked as solution B; Step 2: Add solution B dropwise to solution A at room temperature and stir for 6 hours; Step 3: Wash the above materials with deionized water by centrifugation and dry them in vacuum at 60°C for 18 hours to obtain the final product.

Claims

1. A method for preparing Prussian blue and the like by precipitation conversion reaction, characterized in that: include: Ferrocyanide, transition metal salt and solvent are mixed at one time, firstly undergo precipitation conversion reaction to generate a precipitate containing the target product, and then washed and dried to obtain the Prussian blue and the like.

2. The method according to claim 1, characterized in that The ferrocyanide is at least one of sodium ferrocyanide, potassium ferrocyanide, ammonium ferrocyanide, sodium ferrocyanide, potassium ferrocyanide and ammonium ferrocyanide.

3. The method according to claim 1 or 2, characterized in that: The cation in the transition metal salt is at least one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and the anion is SO4 2- ,CO3 2- 、NO3 - , Cl - Br ─ At least one of the following: the molar ratio of the transition metal salt to ferrocyanide is (5-0.5):

1.

4. The method according to any one of claims 1 to 3, characterized in that The solvent includes at least one of methanol, ethanol, ethylene glycol, isopropanol, glycerol, ether, propylene oxide, acetone, methyl butyl ketone, methyl isobutyl ketone, acetonitrile, trimethyl phosphate, triethyl phosphate, ethylene carbonate, propylene carbonate, dimethyl sulfoxide, sulfolane, methyl acetate, ethyl acetate, propyl acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, pyridine, phenol, and water; The ratio of the transition metal salt to the solvent is 1 mmoL: (0.1-20) mL.

5. The method according to any one of claims 1 to 4, characterized in that The reaction temperature is 0 to 200° C., and the reaction time is 1 to 72 hours. Preferably, the reaction is carried out in a water bath, an oil bath, solvent heat, ball milling or microwave-assisted synthesis.

6. The method according to any one of claims 1 to 5, characterized in that The drying is vacuum drying, the vacuum drying temperature is 30°C to 200°C, the time is 2 to 48 hours, and the vacuum degree is less than 10 kPa.

7. Prussian blue and the like prepared according to the method of any one of claims 1 to 6.

8. Use of the Prussian blue and the like according to claim 7 in a battery.

9. The use according to claim 8, characterized in that: The Prussian blue and the like are used as positive electrode materials or negative electrode materials.

10. The use according to claim 8, characterized in that: The batteries include lithium ion batteries, sodium ion batteries, potassium ion batteries, ammonium ion batteries, zinc ion batteries, magnesium ion batteries, and calcium ion batteries.

Images