Preparation method of functionalized iron oxide nanoparticles, and products and applications thereof

Abstract

The application discloses a preparation method of functionalized iron oxide nanoparticles. Firstly, the interlayer distance of graphite is increased under the action of a bicarbonate ammonia dispersant through high-energy ball milling treatment, and bismuth trisulfide which can inhibit hydrogen evolution is uniformly loaded on the graphite powder through the ball milling effect; then, the formed iron oxide and bismuth trisulfide are fully mixed through an in-situ deposition method; after further high-energy ball milling treatment to form uniform particles, the particles are subjected to hydrothermal treatment together with carbon nanotubes, so that the carbon nanotubes and the graphite and iron oxide particles form an interwoven network structure, a large amount of space is provided in the electrode, and the interlayer structure of the graphite also fully weakens the passivation phenomenon of the iron electrode. When the functionalized iron oxide nanoparticles are applied to an iron-air battery, the main problems existing in the iron-air battery can be solved in a targeted manner, and the application has important practical significance.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy and its materials, specifically, it provides a functionalized iron oxide nanoparticle, its products and applications. Background Technology

[0002] Iron-air batteries have distinct advantages over other metal-air batteries. Firstly, iron is a widely available resource with low extraction costs and is environmentally friendly. Secondly, iron-air batteries boast a theoretical specific capacity as high as 1276 mA h / g. Thirdly, they do not generate dendrites during charge and discharge. However, research reports on iron-air batteries are currently limited. The main reason is that a passivation layer easily forms on the iron electrode surface during charge and discharge, severely reducing battery performance. Additionally, during storage and use, the active material iron in the electrode spontaneously dissolves, producing hydrogen gas, which not only shortens battery life but also increases internal pressure. Another issue is that during charge and discharge, the active material iron expands due to the high water content in the oxidation products, while the reduction reaction during charging causes shrinkage. This phenomenon makes the active material prone to detaching from the current collector, further degrading battery performance.

[0003] This invention functionalizes iron oxide nanoparticles to specifically address issues such as passivation, hydrogen evolution, and volume changes during use in iron electrodes. First, bismuth trisulfide, which inhibits hydrogen evolution, is fully dispersed and loaded onto graphite powder through high-energy ball milling. Then, iron oxide is formed through in-situ deposition and thoroughly mixed with bismuth trisulfide. After thorough homogenization, it is hydrothermally treated together with carbon nanotubes. The carbon nanotubes, graphite, and iron oxide particles form an intertwined network structure, providing ample internal space within the electrode. Furthermore, the interlayer structure of the graphite significantly reduces passivation of the iron electrode. The functionalized iron oxide of this invention has significant practical implications for iron-air batteries. Summary of the Invention

[0004] The purpose of this invention is to provide functionalized iron oxide nanoparticles, their products, and their applications.

[0005] To achieve the above objectives, the embodiment of the present invention is as follows: a method for preparing functionalized iron oxide nanoparticles, comprising the following steps:

[0006] (1) Mix Bi2S3: graphite powder: ammonium bicarbonate in a mass ratio of 1:2:10 and grind thoroughly to obtain precursor-1;

[0007] (2) The precursor-1 was heated at 120°C and cooled to obtain precursor-2;

[0008] (3) The above precursor-2 was ultrasonically dispersed in water, and iron salt was added while stirring continuously to form a uniform dispersion. The dispersion was then heated to 70°C, and concentrated ammonia was slowly added while stirring continuously. When the pH was 7-8, the addition of concentrated ammonia was stopped, and stirring was continued at 70°C. The mixture was then cooled to room temperature, filtered, washed with water, and the resulting solid was vacuum dried at 40°C to obtain precursor-3.

[0009] The iron salt is Fe(NO3)3·9H2O or FeCl3·6H2O; the mass ratio of the precursor-2 to the iron salt is 1:(50~150);

[0010] (4) Transfer precursor-3 into a ball mill, add an appropriate amount of ethanol, ball mill thoroughly, and dry to obtain precursor-4;

[0011] (5) The precursor-4 was transferred into a hydrothermal reactor, carbon nanotubes and an appropriate amount of water were added, the mixture was heated to 120°C, filtered, washed with water, and vacuum dried at 40°C. The resulting solid was functionalized iron oxide nanoparticles.

[0012] The mass ratio of the precursor-4 to the carbon nanotube is 8:(1~3);

[0013] (6) N-methylpyrrolidone and polyvinylidene fluoride are mixed evenly in a mass ratio of 88:12 and used as a binder. Then, an appropriate amount of the binder is mixed with functionalized iron oxide nanoparticles and stirred evenly. The resulting paste is then coated on the surface of a stainless steel mesh and dried under vacuum at 40°C. After that, a stainless steel mesh is placed on the surface coated with the paste and heated to set, thus obtaining an iron electrode.

[0014] In step (6), the stainless steel mesh is 300 mesh stainless steel mesh. During the heat setting process, it is heated to 120°C on a hot press and maintained at a pressure of 25 kN.

[0015] A functionalized iron oxide nanoparticle prepared according to the method described above.

[0016] An application of functionalized iron oxide nanoparticles prepared by the method described above in iron-air batteries.

[0017] This invention first uses high-energy ball milling with ammonium bicarbonate dispersant to increase the interlayer distance of graphite. Simultaneously, ball milling uniformly loads bismuth trisulfide, which inhibits hydrogen evolution, onto the graphite powder. Next, iron oxide and bismuth trisulfide are thoroughly mixed through in-situ deposition. Further high-energy ball milling forms uniform particles, which are then hydrothermally treated with carbon nanotubes. The carbon nanotubes form an intertwined network structure with the graphite and iron oxide particles, creating ample space within the electrode. Furthermore, the interlayer structure of the graphite significantly reduces the passivation phenomenon of the iron electrode. When applied to iron-air batteries, the functionalized iron oxide nanoparticles of this invention can specifically address the main problems existing in iron-air batteries, possessing significant practical value. Detailed Implementation Example

[0018] The preparation and application of functionalized iron oxide nanoparticles include the following steps:

[0019] (1) Mix 1 g Bi2S3, 2 g graphite powder and 10 g ammonium bicarbonate and transfer them into a high-energy ball mill jar. Add 150 g agate balls with a diameter of 5 mm and grind at 400 rpm for 6 hours to obtain precursor-1.

[0020] (2) The precursor-1 was heated at 120°C for 1 hour and then cooled to obtain precursor-2.

[0021] (3) The above precursor-2 was ultrasonically dispersed in water, and 150 g of Fe(NO3)3·9H2O was added while stirring continuously to form a uniform dispersion. The dispersion was then heated to 70°C, and concentrated ammonia was slowly added while stirring continuously until the pH reached 7-8. The addition of concentrated ammonia was stopped, and stirring was continued at 70°C for 1 hour. Finally, the mixture was cooled to room temperature, filtered, washed with water 3 times, and the resulting solid was vacuum dried at 40°C for 6 hours to obtain precursor-3.

[0022] (4) Transfer precursor-3 into a high-energy ball mill, add an appropriate amount of ethanol and agate balls with a mass 50 times that of precursor-3, and ball mill at 350 rpm for 3 hours. After drying, precursor-4 is obtained.

[0023] (5) The precursor-4 was transferred into a hydrothermal reactor, 2 g of carbon nanotubes and an appropriate amount of water were added, the mixture was heated to 120°C for 2 hours, filtered, washed with water, and vacuum dried at 40°C for 10 hours. The resulting solid was functionalized iron oxide nanoparticles.

[0024] (6) N-methylpyrrolidone and polyvinylidene fluoride were mixed evenly at a mass ratio of 88:12 and used as a binder. An appropriate amount of this binder was then mixed with 200 mg of functionalized iron oxide nanoparticles. After thorough mixing, the resulting paste was coated onto the surface of a 300-mesh stainless steel mesh and vacuum dried at 40°C. A stainless steel mesh was then placed on the surface coated with the paste, and the mixture was heated to 120°C and maintained at a pressure of 25 kN for 4 minutes in a hot press to obtain an iron electrode. This iron electrode was then combined with an air electrode prepared from Pt / C to form an iron-air battery. The battery was tested at 4 mol × L⁻¹. -1 NH4Cl + 1 mol×L -1 The battery was subjected to cyclic charge-discharge tests in a mixed solution of KCl: first at 8 mA cm⁻¹ -2 The battery was charged at a current density of 1.8 V, with the cutoff voltage set at 1 mA cm⁻¹. -2 The battery was subjected to cyclic charge-discharge tests at a current density of 25 min for both charging and discharging, with a 5 min rest period between charging and discharging. The battery was able to stably cycle charge and discharge for more than 80 hours, with the voltage efficiency maintained at around 35%. Example

[0025] The preparation and application of functionalized iron oxide nanoparticles include the following steps:

[0026] (1) Mix 1 g Bi2S3, 2 g graphite powder and 10 g ammonium bicarbonate and transfer them into a high-energy ball mill jar. Add 150 g agate balls with a diameter of 5 mm and grind at 400 rpm for 6 hours to obtain precursor-1.

[0027] (2) The precursor-1 was heated at 120°C for 1 hour and then cooled to obtain precursor-2.

[0028] (3) The above precursor-2 was ultrasonically dispersed in water, and 300 g of Fe(NO3)3·9H2O was added while stirring continuously to form a uniform dispersion. The dispersion was then heated to 70°C, and concentrated ammonia was slowly added while stirring continuously until the pH reached 7-8. The addition of concentrated ammonia was stopped, and stirring was continued at 70°C for 1 hour. Finally, the mixture was cooled to room temperature, filtered, washed with water 3 times, and the resulting solid was vacuum dried at 40°C for 6 hours to obtain precursor-3.

[0029] (4) Transfer precursor-3 into a high-energy ball mill, add an appropriate amount of ethanol and agate balls with a mass 50 times that of precursor-3, and ball mill at 350 rpm for 3 hours. After drying, precursor-4 is obtained.

[0030] (5) The precursor-4 was transferred into a hydrothermal reactor, 4 g of carbon nanotubes and an appropriate amount of water were added, the mixture was heated to 120°C for 2 hours, filtered, washed with water, and vacuum dried at 40°C for 10 hours. The resulting solid was functionalized iron oxide nanoparticles.

[0031] (6) N-methylpyrrolidone and polyvinylidene fluoride were mixed evenly at a mass ratio of 88:12 and used as a binder. An appropriate amount of this binder was then mixed with 200 mg of functionalized iron oxide nanoparticles. After thorough mixing, the resulting paste was coated onto the surface of a 300-mesh stainless steel mesh and vacuum dried at 40°C. A stainless steel mesh was then placed on the surface coated with the paste, and the mixture was heated to 120°C and maintained at a pressure of 25 kN for 4 minutes in a hot press to obtain an iron electrode. This iron electrode was then combined with an air electrode prepared from Pt / C to form an iron-air battery. The battery was tested at 4 mol × L⁻¹. -1 NH4Cl + 1 mol×L -1 The battery was subjected to cyclic charge-discharge tests in a mixed solution of KCl: first at 8 mA cm⁻¹ -2 The battery was charged at a current density of 1.8 V, with the cutoff voltage set at 1 mA cm⁻¹. -2 The battery was subjected to cyclic charge-discharge tests at a current density of 25 min for both charging and discharging, with a 5 min rest period between charging and discharging. The battery was able to stably cycle charge and discharge for more than 80 hours, with the voltage efficiency maintained at around 47%. Example

[0032] The preparation and application of functionalized iron oxide nanoparticles include the following steps:

[0033] (1) Mix 1 g Bi2S3, 2 g graphite powder and 10 g ammonium bicarbonate and transfer them into a high-energy ball mill jar. Add 150 g agate balls with a diameter of 5 mm and grind at 400 rpm for 6 hours to obtain precursor-1.

[0034] (2) The precursor-1 was heated at 120°C for 1 hour and then cooled to obtain precursor-2.

[0035] (3) The above precursor-2 was ultrasonically dispersed in water, and 450 g of Fe(NO3)3·9H2O was added while stirring continuously to form a uniform dispersion. The dispersion was then heated to 70°C, and concentrated ammonia was slowly added while stirring continuously until the pH reached 7-8. The addition of concentrated ammonia was stopped, and stirring was continued at 70°C for 1 hour. Finally, the mixture was cooled to room temperature, filtered, washed with water 3 times, and the resulting solid was vacuum dried at 40°C for 6 hours to obtain precursor-3.

[0036] (4) Transfer precursor-3 into a high-energy ball mill, add an appropriate amount of ethanol and agate balls with a mass 50 times that of precursor-3, and ball mill at 350 rpm for 3 hours. After drying, precursor-4 is obtained.

[0037] (5) The precursor-4 was transferred into a hydrothermal reactor, 6 g of carbon nanotubes and an appropriate amount of water were added, the mixture was heated to 120°C for 2 hours, filtered, washed with water, and vacuum dried at 40°C for 10 hours. The resulting solid was functionalized iron oxide nanoparticles.

[0038] (6) N-methylpyrrolidone and polyvinylidene fluoride were mixed evenly at a mass ratio of 88:12 and used as a binder. An appropriate amount of this binder was then mixed with 200 mg of functionalized iron oxide nanoparticles. After thorough mixing, the resulting paste was coated onto the surface of a 300-mesh stainless steel mesh and vacuum dried at 40°C. A stainless steel mesh was then placed on the surface coated with the paste, and the mixture was heated to 120°C and maintained at a pressure of 25 kN for 4 minutes in a hot press to obtain an iron electrode. This iron electrode was then combined with an air electrode prepared from Pt / C to form an iron-air battery. The battery was tested at 4 mol × L⁻¹. -1 NH4Cl + 1 mol×L -1 The battery was subjected to cyclic charge-discharge tests in a mixed solution of KCl: first at 8 mA cm⁻¹ -2 The battery was charged at a current density of 1.8 V, with the cutoff voltage set at 1 mA cm⁻¹. -2 Cyclic charge-discharge tests were conducted at a current density of 25 min for both charging and discharging, with a 5 min rest period between charging and discharging. The battery was able to stably cycle charge and discharge for more than 80 hours, maintaining a voltage efficiency of around 42%. Example

[0039] The preparation and application of functionalized iron oxide nanoparticles include the following steps:

[0040] (1) Mix 1 g Bi2S3, 2 g graphite powder and 10 g ammonium bicarbonate and transfer them into a high-energy ball mill jar. Add 150 g agate balls with a diameter of 5 mm and grind at 400 rpm for 6 hours to obtain precursor-1.

[0041] (2) The precursor-1 was heated at 120°C for 1 hour and then cooled to obtain precursor-2.

[0042] (3) The above precursor-2 was ultrasonically dispersed in water, and 300 g of FeCl3·6H2O was added while stirring continuously to form a uniform dispersion. The dispersion was then heated to 70°C, and concentrated ammonia was slowly added while stirring continuously until the pH reached 7-8. The addition of concentrated ammonia was stopped, and stirring was continued at 70°C for 1 hour. Finally, the mixture was cooled to room temperature, filtered, washed three times with water, and the resulting solid was vacuum dried at 40°C for 6 hours to obtain precursor-3.

[0043] (4) Transfer precursor-3 into a high-energy ball mill, add an appropriate amount of ethanol and agate balls with a mass 50 times that of precursor-3, and ball mill at 350 rpm for 3 hours. After drying, precursor-4 is obtained.

[0044] (5) The precursor-4 was transferred into a hydrothermal reactor, 4 g of carbon nanotubes and an appropriate amount of water were added, the mixture was heated to 120°C for 2 hours, filtered, washed with water, and vacuum dried at 40°C for 10 hours. The resulting solid was functionalized iron oxide nanoparticles.

[0045] (6) N-methylpyrrolidone and polyvinylidene fluoride were mixed evenly at a mass ratio of 88:12 and used as a binder. An appropriate amount of this binder was then mixed with 200 mg of functionalized iron oxide nanoparticles. After thorough mixing, the resulting paste was coated onto the surface of a 300-mesh stainless steel mesh and vacuum dried at 40°C. A stainless steel mesh was then placed on the surface coated with the paste, and the mixture was heated to 120°C and maintained at a pressure of 25 kN for 4 minutes in a hot press to obtain an iron electrode. This iron electrode was then combined with an air electrode prepared from Pt / C to form an iron-air battery. The battery was tested at 4 mol × L⁻¹. -1 NH4Cl + 1 mol×L -1 The battery was subjected to cyclic charge-discharge tests in a mixed solution of KCl: first at 8 mA cm⁻¹ -2 The battery was charged at a current density of 1.8 V, with the cutoff voltage set at 1 mA cm⁻¹. -2 The battery was subjected to cyclic charge-discharge tests at a current density of 25 min for both charging and discharging, with a 5 min rest period between charging and discharging. The battery was able to stably cycle charge and discharge for more than 80 hours, with the voltage efficiency maintained at around 46%.

Claims

1. A method for preparing an iron electrode, characterized in that, Includes the following steps: (1) Mix Bi2S3: graphite powder: ammonium bicarbonate in a mass ratio of 1:2:10 and grind thoroughly to obtain precursor-1; (2) The precursor-1 was heated at 120°C and cooled to obtain precursor-2; (3) The above precursor-2 was ultrasonically dispersed in water, and iron salt was added while stirring continuously to form a uniform dispersion. The dispersion was then heated to 70°C, and concentrated ammonia was slowly added while stirring continuously. When the pH was 7-8, the addition of concentrated ammonia was stopped, and stirring was continued at 70°C. The mixture was then cooled to room temperature, filtered, washed with water, and the resulting solid was vacuum dried at 40°C to obtain precursor-3. The iron salt is Fe(NO3)3·9H2O or FeCl3·6H2O; the mass ratio of the precursor-2 to the iron salt is 1:(50~150); (4) Transfer precursor-3 into a ball mill, add an appropriate amount of ethanol, ball mill thoroughly, and dry to obtain precursor-4; (5) The precursor-4 was transferred into a hydrothermal reactor, carbon nanotubes and an appropriate amount of water were added, the mixture was heated to 120°C, filtered, washed with water, and vacuum dried at 40°C. The resulting solid was functionalized iron oxide nanoparticles. The mass ratio of the precursor-4 to the carbon nanotube is 8:(1~3); (6) N-methylpyrrolidone and polyvinylidene fluoride are mixed evenly in a mass ratio of 88:12 and used as a binder. Then, an appropriate amount of the binder is mixed with functionalized iron oxide nanoparticles and stirred evenly. The resulting paste is then coated on the surface of a stainless steel mesh and dried under vacuum at 40°C. After that, a stainless steel mesh is placed on the surface coated with the paste and heated to set, thus obtaining an iron electrode.

2. The method for preparing the iron electrode according to claim 1, characterized in that, In step (6), the stainless steel mesh is 300 mesh stainless steel mesh. During the heat setting process, it is heated to 120°C on a hot press and maintained at a pressure of 25 kN.

3. An iron electrode prepared according to the method of claim 1.

4. The application of an iron electrode prepared by the method described in claim 1 in iron-air batteries.