CN104916449A - Preparation method of supercapacitor ferrous titanate nanoflower electrode material - Google Patents

Abstract

The invention relates to a method for preparing an electrode material of iron titanate nanoflowers for a supercapacitor, belonging to the technical field of electrode material preparation; the method uses natural ilmenite as a raw material, and after simple mechanical ball milling, ball mill powder is mixed into sodium hydroxide The solution was heated and stirred, and then solid-liquid separation was achieved by filtration. After drying, a three-dimensional petal-shaped nano-iron titanate (FeTiO ₃ ) electrode material for a supercapacitor with good electrochemical performance was obtained; the obtained electrode material nano-flower was composed of a certain amount of Composed of petals with smooth surfaces, the thickness and width of each petal are 5~20 and 100~200 nm, respectively. The capacitive behavior of FeTiO ₃ nanoflowers was evaluated in 3M KCl, 1M H ₂ SO ₄ and 1M KOH aqueous electrolytes, respectively, and the results It was found that FeTiO ₃ nanoflowers in 1M KOH electrolyte, when the current density is 0.5A/g~05A/g, the capacitance of FeTiO ₃ nanoflowers can keep fluctuating within a reasonable range. This method is simple and easy The operation and cost are low, the application potential is great, and the application and industrialization prospects are good.

Description

A kind of preparation method of supercapacitor iron titanate nano flower electrode material

technical field

The invention relates to a preparation method of an electrode material of iron titanate nanoflowers for a supercapacitor, in particular to a method for preparing an electrode material of iron titanate nanoflowers for a supercapacitor with special appearance, large specific surface area, high purity and superior performance, and belongs to electrode materials The field of preparation technology.

Background technique

Ilmenite (FeTiO ₃ ) is a cheap and abundant natural mineral resource. It is the most important mineral raw material for extracting titanium and titanium dioxide. Ilmenite is heavy, gray to black, with a little metallic luster. The crystal is generally plate-shaped. The crystals are grouped together as massive or granular. They are widely distributed around the world, such as: North America (United States and Canada), South America (Brazil), Oceania (Australia), Europe (Russia and Norway), Asia (China, India and Vietnam) and Africa (South Africa and Mozambique) ), 4 well-known mines include Ilmen Mountain in Russia, Kragler in Norway, Iron Mountain in Wyoming, USA, Elard Lake in Quebec, Canada, etc. Panzhihua Iron Mine in Sichuan, China, is also a large-scale ilmenite producing area. Its ilmenite is in the form of fine particles or flakes, distributed between magnetite particles or cracks.

Ilmenite is one of the main titanium-containing minerals, trigonal crystal system, rare crystals, often in irregular granular, scaly, plate-like or flaky shapes; the color is iron black or steel gray, streaked steel gray or black, when it contains Hematite inclusions are brown or brownish red; metallic to semi-metallic luster, conchoidal or subconchular fractures; brittle, with a hardness of 5-6 and a density of 4.4-5g/cm3, and the density decreases with the content of MgO in the composition Or the content of FeO increases and increases; with weak magnetic properties, ilmenite can be produced in various rock masses, and is widely distributed in basic rocks and acidic rocks. Ilmenite is also a semiconductor with a bandgap width of 2.54-2.58 eV and obvious magnetic properties. In the laboratory, they can also be successfully synthesized by chemical methods. Among them, nanostructured FeTiO ₃ has exhibited some attractive properties and novel applications, for example, heterostructured FeTiO ₃ nanodiscs and TiO ₂ particles composited as photocatalysts have a significantly improved photocatalytic performance.

So far, only two literatures have reported the synthesis of nanostructured ilmenite. First, let FeSO ₄ 7H ₂ O and titanium isopropoxide react hydrothermally in tetrabutylammonium hydroxide aqueous solution at a temperature of 220°C, and finally obtain single-crystal FeTiO ₃ nanodiscs; Ohara et al. Mechanical ball milling of TiO ₂ in a container can produce agglomerated FeTiO ₃ nanoparticles.

In view of the above-mentioned research status, the present invention has synthesized three-dimensional petal-shaped nano-iron titanate (FeTiO ₃ ) with a special shape by means of mechanical ball milling combined with hydrothermal methods. FeTiO ₃ nano-flowers are composed of a certain number of petals with smooth surfaces, and each petal The thickness and width are 5-20 and 100-200 nm, respectively. Electrochemical test results show that the capacitance of three-dimensional petal-shaped nano-iron titanate (FeTiO ₃ ) is 120F/g, and the measured current density is 500mA/g. Therefore, it has special shape, uniform structure, high purity and good electrochemical performance FeTiO ₃ nanoflowers can be used as one of the candidate electrode materials for electrochemical supercapacitors.

Contents of the invention

The purpose of the present invention is to solve the problems of high cost and low capacity of supercapacitor electrode materials, and provide a method for preparing a new three-dimensional petal-shaped nanometer iron titanate (FeTiO ₃ ) electrode material for supercapacitors. Thermal method, the present invention uses cheap and abundant ilmenite as raw material to prepare a new three-dimensional petal-shaped nano-iron titanate (FeTiO ₃ ) electrode material for a supercapacitor with low cost, superior performance, and high safety, and realizes iron titanate (FeTiO 3 ) electrode material. ₃ ) The effectiveness and environmental friendliness of the nano-electrode material preparation technology application.

To achieve the above object, the technical solution adopted in the present invention is:

A preparation method for a super capacitor iron titanate nano flower electrode material, comprising the steps of:

(1) Under the protection of 100 Kpa Ar, put the ilmenite and 4 stainless steel balls with a diameter of 25.4 mm into the ball mill pot, and mill for 140~160 h. The horizontal direction is at an angle of 45 degrees, and the rotation speed is 160 rpm;

(2) After ball milling, mix the ball mill powder into 2M sodium hydroxide solution, the weight ratio of ball mill powder to sodium hydroxide is 1:8, and then heat at a constant temperature of 110~130°C for 1~3 hours, the heating process is accompanied by stirring, Stirring rate is constant at 800rpm;

(3) After the heating is completed, solid-liquid separation is achieved by filtration, and the repeatedly washed solid is dried in an oven at a temperature of 90°C for 3 to 5 hours. The dried product is three-dimensional petal-shaped nano titanic acid Iron (FeTiO ₃ ) electrode material, iron titanate (FeTiO3) nano flower structure is special, suitable for ion adsorption and storage, this method is an environmentally friendly method for preparing iron titanate (FeTiO3) nano flower electrode material.

In conjunction with accompanying drawing, further illustrate the present invention, as can be seen from Fig. 1, the ilmenite after ball milling is mainly made up of many small particles that agglomerate together and are several to more than ten nanometers in size, because the material is processed by ball milling , often have a nanocrystalline structure, and these nanocrystals often agglomerate together. From c and d in Figure 1, it can be seen that after the ilmenite ball mill powder is treated with hot alkali, the obtained product is composed of many particles with a diameter of 1-2 μm flower-like structure. In these flower-like structures, each petal The thickness is 5~20nm, and the width is 100~200nm.

It can be known from Fig. 2 that the X-ray diffraction pattern of the flower-shaped nano-product is similar to that of the ilmenite ball mill powder, and is almost consistent with the standard pattern of FeTiO3 (JCPDS 01-075-1211), indicating that ball milling and Thermal alkali treatment does not change the chemical composition of ilmenite, but, compared with the standard spectrum, their diffraction peaks become weaker and wider, which are typical characteristics of small crystal size.

The beneficial effects of the present invention are: the preparation method of a novel supercapacitor three-dimensional petal-shaped nano iron titanate (FeTiO ₃ ) electrode material of the present invention, combined with the ball milling hydrothermal process, has the advantages of simple production process, low cost and great application potential and other characteristics, the new three-dimensional petal-shaped nano-iron titanate (FeTiO ₃ ) electrode material prepared for supercapacitors has a relatively large specific surface area, special shape, and relatively uniform size. The nano-flowers are composed of a certain number of petals with smooth surfaces. The thickness and width of each petal are 5-20 nm and 100-200 nm, respectively, with good electrochemical performance and high safety. Therefore, this three-dimensional petal-shaped nano-iron titanate (FeTiO ₃ ) electrode material has great potential in the field of supercapacitors. Potential application value has good application and industrialization prospects.

Instructions attached

Fig.1 Scanning electron micrograph of the sample

Among them (a) and (b) are the ilmenite after ball milling for 100 hours, (c) and (d) are the products obtained by boiling the ball milled ilmenite powder in hot 2 M NaOH solution for 2 hours

Fig.2 X-ray diffraction patterns of ball-milled ilmenite powder and three-dimensional ilmenite nanoflowers

The line at the bottom of the figure represents the X-ray diffraction standard pattern of FeTiO ₃ phase (JCPDS 01-075-1211)

Fig. 3 Cyclic voltammetry curves of iron ore nanoflower electrodes measured in three different aqueous electrolytes.

Detailed ways

The present invention is described in further detail below by example, and these examples are only used for illustrating the present invention, do not limit the scope of the present invention;

Example 1

Put ilmenite and 4 stainless steel balls with a diameter of 25.4 mm into a ball mill jar, and then ball mill for 150 h under the protection of 100 Kpa Ar. Degree angle, rotating speed is 160 rpm, pour the ball-milled sample into 2M sodium hydroxide solution, the weight ratio of ball mill powder to sodium hydroxide is 1:8, and then heat at 120°C for 2 hours, the heating process is accompanied by stirring , the stirring rate is constant at 800rpm. After the heating is completed, the solid-liquid separation is achieved by filtration. The solid after repeated washing is dried in an oven at a temperature of 90°C for 4 hours. The dried sample is _FeTiO 3nm Flower products, FeTiO ₃ nanoflowers are composed of a certain number of petals with a smooth surface, and the thickness and width of each petal are 5-20 and 100-200 nm, respectively.

The capacitive behavior of FeTiO ₃ nanoflowers was evaluated in 3M KCl, 1M H ₂ SO ₄ and 1M KOH aqueous electrolytes, respectively, and it was found that the capacitance values of FeTiO ₃ nanoflowers in 3M KCl and 1M KOH electrolytes are attractive, especially In 1M KOH electrolyte, when the current density is 0.5A/g, the capacitance of FeTiO ₃ nanoflowers is 120 F/g, and when the current density increases to 05A/g, the capacitance of FeTiO ₃ nanoflowers can also be kept at a reasonable The capacity of the FeTiO ₃ nanoflower electrode remains almost unchanged when the charge-discharge times exceed 1000. The simple and environmentally friendly preparation process, high specific capacity and excellent cycle performance make this material promising as a new cathode material for high-performance supercapacitors.

Figure 3 is the cyclic voltammetry curves of iron ore nanoflower electrodes measured in three different aqueous electrolytes: 3 M KCl (a), 1 M H ₂ SO ₄ (b) and 1 M KOH (c), at a scan rate of 5 and 50mV/s and galvanostatic charge-discharge tests of iron ore nanoflower electrodes carried out in 1M KOH aqueous electrolyte; (d) under the conditions of current density of 0.5 A/g and 2A/g, the measured electrode material Galvanostatic charge-discharge curve; (e) cycle stability of the electrode material at a current density of 0.5 A/g; (f) capacitance retention of the electrode material under high current load.

Figure 3a–c presents the cyclic voltammetry curves of iron ore nanoflower electrodes measured in three different aqueous electrolytes, namely 3 M _KCl , 1M _H2SO4 and 1M KOH, at a scan rate of 5 and 50 mV/s, the test results show that the iron iron ore nanoflowers have obvious pseudocapacitive behavior in the three electrolytes. The potential ranges of ilmenite nanoflowers in 3M KCl, 1M H ₂ SO ₄ and 1M KOH electrolytes are -1.2~-0.4 V (vs Ag/AgCl), 0~0.9 V (vs Ag/AgCl) and -1.2 V ~-0.4V (vs Hg/HgO). When the scan rate was 5 mV/s, the shape of the CV curve related to the 3M KCl electrolyte was close to a rectangle, while there was a pair of redox peaks in the CV curve of the 1M H ₂ SO ₄ electrolyte. In addition, as shown in Fig. 3a–c, the area enclosed by the CV curves of the working electrode measured in 1M _H2SO4 electrolyte is relatively small compared with 3M _KCl and 1M KOH, indicating that the iron ore nanoflower electrode is at 1M _The electricity storage capacity in the _H2SO4 electrolyte is low. When the scan rate increased to 50mV/s, the shape of the CV curve was close to an ellipse, indicating that the conductivity of the electrode was insufficient. The electrochemical properties of FeTiO ₃ nanoflowers were evaluated by galvanostatic charge-discharge experiments. The electrodes of FeTiO ₃ nanoflowers used contained 20% carbon black, the electrolyte was 1 M KOH solution, and the potential range was -1.2~-0.4V (vs Hg/HgO), the current density increased from 0.5 A/g to 5 A/g. Figure 3d shows the measured constant current charge and discharge curves of the FeTiO ₃ nanoflower electrode under the conditions of current density of 0.5 A/g and 2A/g, and the capacitance at 0.5A/g is 121F/g. Figure 3e shows the cycle life of the supercapacitor, the number of cycles exceeds 1000 times, and the current density is constant at 0.5 A/g. The measurement results show that after the capacitor is charged and discharged 1000 times, the capacity of the FeTiO ₃ nanoflower electrode remains almost unchanged, and the capacitance There was no noticeable decline. Figure 3f shows the capacitance of the FeTiO ₃ nanoflower electrode at different current densities. It can be seen from the figure that when the current density increases to 5 A/g, the capacitance of the FeTiO ₃ nanoflower electrode can still be maintained at 50F/g. Compared with ball-milled ilmenite, the capacitance of ilmenite nanoflowers is greatly improved, which may be due to the high specific surface area (26 m2/g) and interconnected three-dimensional layered structure of ilmenite nanoflowers. .

Example 2

Under the protection of 100 Kpa Ar, put ilmenite and 4 stainless steel balls with a diameter of 25.4 mm into a ball milling tank, and mill for 140 h. The whole ball milling process is carried out under the assistance of magnetic force, and the magnet is 45 degrees to the horizontal direction. Angle, the rotation speed is 160 rpm; after ball milling, mix the ball mill powder into 2M sodium hydroxide solution, the weight ratio of ball mill powder to sodium hydroxide is 1:8, and then heat at a constant temperature of 110°C for 1 hour, the heating process is accompanied by stirring, The stirring rate is constant at 800rpm; after the heating is completed, the solid-liquid separation is achieved by filtration, and the repeatedly washed solid is dried in an oven at a temperature of 90°C for 3 hours. The dried product is three-dimensional petal-shaped nano-titanium Iron titanate (FeTiO ₃ ) electrode material, iron titanate (FeTiO3) nano flower structure is special, suitable for ion adsorption and storage, this method is an environmentally friendly method for preparing iron titanate (FeTiO3) nano flower electrode material.

Example 3

Under the protection of 100 Kpa Ar, put the ilmenite and 4 stainless steel balls with a diameter of 25.4 mm into the ball mill jar, and milled for 160 h. The whole ball milling process was carried out under the assistance of magnetic force, and the magnet was 45 degrees to the horizontal direction. Angle, the rotation speed is 160 rpm; after ball milling, mix the ball mill powder into 2M sodium hydroxide solution, the weight ratio of ball mill powder to sodium hydroxide is 1:8, and then heat at a constant temperature of 130°C for 3 hours, the heating process is accompanied by stirring, The stirring rate is constant at 800rpm; after the heating is completed, the solid-liquid separation is achieved by filtration, and the repeatedly washed solid is dried in an oven at a temperature of 90°C for 5 hours. The dried product is a three-dimensional petal-shaped nano-titanium Iron titanate (FeTiO ₃ ) electrode material, iron titanate (FeTiO3) nano flower structure is special, suitable for ion adsorption and storage, this method is an environmentally friendly method for preparing iron titanate (FeTiO3) nano flower electrode material.

Example 4

Under the protection of 100 Kpa Ar, put ilmenite and 4 stainless steel balls with a diameter of 25.4 mm into a ball milling tank, and mill for 145 h. The whole ball milling process is carried out under the assistance of magnetic force, and the magnet is 45 degrees to the horizontal direction. Angle, the rotation speed is 160 rpm; after ball milling, mix the ball mill powder into 2M sodium hydroxide solution, the weight ratio of ball mill powder to sodium hydroxide is 1:8, and then heat at a constant temperature of 115°C for 1.5 hours, the heating process is accompanied by stirring, The stirring rate is constant at 800rpm; after the heating is completed, the solid-liquid separation is achieved by filtration, and the repeatedly washed solid is dried in an oven at a temperature of 90°C for 3 hours. The dried product is three-dimensional petal-shaped nano-titanium Iron titanate (FeTiO ₃ ) electrode material, iron titanate (FeTiO3) nano flower structure is special, suitable for ion adsorption and storage, this method is an environmentally friendly method for preparing iron titanate (FeTiO3) nano flower electrode material.

Example 5

Under the protection of 100 Kpa Ar, put ilmenite and 4 stainless steel balls with a diameter of 25.4 mm into a ball milling tank, and mill for 155 h. The whole ball milling process is carried out under the assistance of magnetic force, and the magnet is 45 degrees to the horizontal direction. Angle, the rotation speed is 160 rpm; after ball milling, mix the ball mill powder into 2M sodium hydroxide solution, the weight ratio of ball mill powder to sodium hydroxide is 1:8, and then heat at a constant temperature of 125°C for 3 hours, the heating process is accompanied by stirring, The stirring rate is constant at 800rpm; after the heating is completed, the solid-liquid separation is achieved by filtration, and the repeatedly washed solid is dried in an oven at a temperature of 90°C for 5 hours. The dried product is a three-dimensional petal-shaped nano-titanium Iron titanate (FeTiO ₃ ) electrode material, iron titanate (FeTiO3) nano flower structure is special, suitable for ion adsorption and storage, this method is an environmentally friendly method for preparing iron titanate (FeTiO3) nano flower electrode material.

Claims (6)

1. A preparation method for supercapacitor iron titanate nano flower electrode material, characterized in that: comprise the steps: (1) Under the protection of 100 Kpa Ar, put the ilmenite and stainless steel balls into the ball mill jar, and mill for 140~160 h; (2) After ball milling, mix the ball mill powder into 2 mol/L sodium hydroxide solution, and then heat at a constant temperature of 110~130°C for 1~3 hours. The heating process is accompanied by stirring, and the stirring rate is constant at 800rpm; (3) After the heating is completed, solid-liquid separation is achieved by filtration, and the repeatedly washed solid is dried in an oven at a temperature of 90°C for 3 to 5 hours. The dried product is three-dimensional petal-shaped nano titanic acid iron. 2. The method for preparing a supercapacitor iron titanate nanoflower electrode material according to claim 1, characterized in that: the stainless steel balls in step (1) are four stainless steel balls with a diameter of 25.4 mm. 3. The preparation method of a supercapacitor iron titanate nanoflower electrode material according to claim 1, characterized in that: the entire ball milling process in step (1) is carried out under the auxiliary action of magnetic force, and the magnet and the horizontal direction At a 45-degree angle at 160 rpm. 4. The method for preparing a supercapacitor iron titanate nanoflower electrode material according to claim 1, wherein the atmosphere used in the ball milling in step (1) is argon. 5 . The method for preparing a supercapacitor iron titanate nanoflower electrode material according to claim 1 , wherein the weight ratio of the ball mill powder to sodium hydroxide in step (2) is 1:8. 6. An electrode material of iron titanate nanoflowers for a supercapacitor, characterized in that: the electrode material of iron titanate nanoflowers for a supercapacitor is prepared by the method described in any one of claims 1 to 5.