Preparation and electrochemical performance test of industrial acetylene black / copper-cobalt ferrite composite material

Abstract

The invention discloses preparation and electrochemical performance testing of an industrial acetylene black / copper-cobalt ferrite composite material. The specific method comprises the steps that industrial solid waste acetylene black waste and copper-cobalt ferrite are compounded through a hydrothermal synthesis method, and through coating of a carbonaceous material, on one hand, the mechanical strength of the copper-cobalt ferrite can be improved, so that stress / strain caused by volume change of an electrode in the circulation process is buffered; on the other hand, the carbon material can improve the electronic conductivity of the active material, and in addition, the carbon layer on the surface of the electrode can inhibit excessive accumulation of an SEI film. The electrochemical performance of the prepared composite material is studied by characterizing the microstructure, the crystal form, the optical property, the surface chemical state and the like of the material through a series of performance characterization means, and the analysis result shows that the electrochemical performance of the acetylene black modified copper-cobalt ferrite is greatly improved.

Description

Technical Field

[0001] The invention relates to the preparation and electrochemical performance test of an industrial acetylene black / copper cobalt ferrite composite material, and belongs to the field of electrochemical energy storage. Background Art

[0002] Climate change caused by fossil fuel energy production and the increasing demand for flexible and portable electronic devices have driven the development of renewable energy storage devices. Supercapacitors and batteries have attracted widespread attention for their unique power and energy density in energy storage devices. In recent decades, researchers around the world have been working hard to develop a material suitable for energy storage devices with high energy and power density, long self-life, and good cost-effectiveness. Supercapacitors have key advantages such as high power density, high energy density, high cycle stability, and environmental friendliness. Copper cobalt ferrite, as a potential candidate for supercapacitors, has been less studied. However, its relatively poor conductivity and severe structural collapse during repeated discharge / charge processes will lead to rapid capacity decay and poor rate performance. Therefore, exploring modification methods to effectively improve the electrochemical properties of copper cobalt ferrite still needs in-depth research.

[0003] The copper-cobalt ferrite composite material was prepared by chemical coprecipitation, and then the industrial waste acetylene black was compounded with the copper-cobalt ferrite by hydrothermal synthesis. The coating of carbonaceous materials can improve the mechanical strength of copper-cobalt ferrite on the one hand, so as to buffer the stress / strain caused by the volume change of the electrode during the cycle; on the other hand, the carbon material can improve the electronic conductivity of the active material. In addition, the carbon layer on the electrode surface can inhibit the excessive accumulation of the SEI film. The micromorphology, crystal form, optical properties and surface chemical state of the material were characterized, and the electrochemical properties of the prepared composite material were studied through a series of performance characterization methods. From industrial waste acetylene black to composite materials with high electrochemical properties, it can not only process acetylene black, a by-product of the ironmaking process in the metallurgical industry, but also improve the electrochemical properties of copper-cobalt ferrite. It truly achieves the economical, reasonable, efficient and comprehensive utilization of these considerable carbon resources, which is of great significance for the application research on improving the electrochemical properties of copper-cobalt ferrite. Summary of the invention

[0004] The technical problem to be solved by the present invention is: how to recycle industrial acetylene black waste and improve the electrochemical performance of copper-cobalt ferrite.

[0005] In order to solve the above problems, the technical solutions adopted in this experiment are:

[0006] Coprecipitation is a widely used wet chemical synthesis method. This experiment uses coprecipitation to prepare copper-cobalt ferrite. The steps are as follows:

[0007] (1) Weigh the nitrates of Cu, Co, and Fe in a certain mass ratio, dissolve them in 60 ml of deionized water, and stir while adding (magnetic stirring meter, time is 20 min);

[0008] (2) After the solution is evenly dispersed, keep stirring and add NaOH (precipitant) dropwise at room temperature until the pH of the solution reaches 10. The solution with adjusted pH is heated at 90°C for 2 hours to complete the reaction;

[0009] (3) Centrifuge and wash (the centrifuge speed is set at 4000 r / min) until the pH is neutral. Then dry at room temperature and heat the dried solid in a tube furnace at 700°C for 5 hours.

[0010] Preferably, the stirring time is shortened and the coprecipitation reaction time is prolonged to make the reaction more complete and improve the yield of copper-cobalt ferrite.

[0011] Hydrothermal synthesis is a flexible and efficient material preparation method. In this experiment, acetylene black / copper cobalt ferrite composite materials were prepared by hydrothermal synthesis. The steps are as follows:

[0012] (1) Copper-cobalt ferrite and acetylene black in a mass ratio of 2:1 were mixed and added to 30 ml of deionized water, and magnetic stirring was performed for 30 minutes (later changed to ultrasonic dispersion) to allow the mixture to be completely dispersed and dissolved.

[0013] (2) The dispersed mixed solution was transferred to a high pressure reactor and subjected to hydrothermal reaction at 120°C for 10 h.

[0014] (3) After the hydrothermal treatment, the black precipitate was washed three to four times with deionized water, filtered, and dried to obtain a composite material.

[0015] Preferably, the mass ratio of hydrothermal reaction copper-cobalt ferrite to acetylene black is 2:1.

[0016] Preferably, the hydrothermal temperature during the hydrothermal reaction is 120°C

[0017] Preferably, the hydrothermal reaction time is 10 hours.

[0018] Compared with other methods for improving the electrochemical performance of copper-cobalt ferrite-based composite materials, the present invention has the following significant beneficial effects:

[0019] (1) The present invention adopts a chemical coprecipitation method to prepare a copper-cobalt ferrite composite material, and then uses a hydrothermal synthesis method to compound the industrial waste acetylene black with the copper-cobalt ferrite. The carbonaceous material coating can improve the mechanical strength of the copper-cobalt ferrite on the one hand, so as to buffer the stress / strain caused by the volume change of the electrode during the cycle process.

[0020] (2) Carbon materials can improve the electronic conductivity of active materials. In addition, the carbon layer on the electrode surface can inhibit the excessive accumulation of SEI film.

[0021] (3) The present invention converts industrial waste acetylene black into a composite material with high electrochemical properties. It can not only process acetylene black, a by-product of the iron-making process in the metallurgical industry, but also improve the electrochemical properties of copper-cobalt ferrite, thus truly achieving the economical, reasonable, efficient and comprehensive utilization of these considerable carbon resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Cyclic voltammetry (CV) curves of the composite materials at different scan rates

[0023] Figure 2 The constant current charge and discharge curves (GCD) of the composite material at different current densities

[0024] Figure 3 Transmission scanning electron microscope (TEM) image of the composite material DETAILED DESCRIPTION

[0025] In order to make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0026] Example 1

[0027] Electrochemical determination of composite materials:

[0028] Treatment of nickel foam: Cut the nickel foam into small square pieces of 1cm*1cm in size, and pickle the nickel foam with dilute sulfuric acid solution to remove oxides or impurities on the surface and expose a more active metal surface.

[0029] Preparation of slurry: Use an analytical balance to weigh activated carbon, polyvinylidene fluoride (binder) and acetylene black (conductive agent) in order, with the mass ratio of the three being 8:1:1. Put the weighed materials into a mortar, grind them evenly, then add an appropriate amount of N-methylpyrrolidone and grind again until they become uniform.

[0030] Slurry coating: The slurry is evenly coated on the treated nickel foam and blown dry with a hair dryer. Use a small amount and multiple times method to ensure that the activated carbon is evenly coated on the nickel foam and dry it in a vacuum drying oven at 60°C for 12 hours. Finally, the mass of the activated carbon is calculated after weighing.

[0031] Electrochemical testing of composite electrode using a three-electrode working system

[0032] The parameters for the CV test were set to a potential range of 0 V to 0.5 V and a scan rate of 10–100 mV / s.

[0033] The specific capacitance of the material is calculated by CV, which reflects the energy storage performance of the material. The specific capacitance is usually calculated by the following formula: Among them I peak is the current peak value, Δt is the time, and ΔV is the voltage sweep range.

[0034] When testing GCD, the parameter settings are as follows: voltage window is 0-0.5V, current density is 0.5-10A -1

[0035] The specific capacitance of the material is calculated by GCD, which reflects the energy storage performance of the material. The specific capacitance is usually calculated by the following formula: Where I is the charge and discharge current, Δt is the charge and discharge time, and m is the mass of the active material.

Claims

1. Preparation and electrochemical performance test of an industrial acetylene black / copper cobalt ferrite composite material, characterized in that: The following steps are involved: Step 1) Weigh the nitrates of Cu, Co, and Fe according to a certain mass ratio, dissolve them in 60 ml of deionized water, and stir while adding (magnetic stirrer, time is 20 min); Step 2): After the solution is evenly dispersed, keep stirring, and add NaOH (precipitant) dropwise at room temperature until the pH of the solution reaches 10. The solution with adjusted pH is heated at 90°C for 2 hours to complete the reaction; Step 3): Centrifuge and wash (the centrifuge speed is set to 4000r / min) until the pH is neutral. Then dry at room temperature, heat the dried solid in a tubular furnace, and heat at 700°C for 5 hours. Step 4): The copper-cobalt ferrite is compounded with industrial solid waste acetylene black waste by hydrothermal synthesis, and then its electrochemical properties are measured using a three-electrode working system.

2. The preparation and electrochemical performance test of an industrial acetylene black / copper cobalt ferrite composite material according to claim 1, characterized in that: The mass ratio of the weighed Cu, Co and Fe nitrates is Cu:Co:Fe=1:1:

2.

3. The preparation and electrochemical performance test of an industrial acetylene black / copper cobalt ferrite composite material according to claim 1, characterized in that: The pH of the solution was 10 when the copper-cobalt ferrite was prepared by the coprecipitation method.

4. The preparation and electrochemical performance test of an industrial acetylene black / copper cobalt ferrite composite material according to claim 1, characterized in that: When heated by a tubular furnace, the heating temperature is 700°C and the heating time is 5 hours.

5. The preparation and electrochemical performance test of an industrial acetylene black / copper cobalt ferrite composite material according to claim 1, characterized in that: During the hydrothermal synthesis, the composite ratio of copper-cobalt ferrite to acetylene black was 2:1, the hydrothermal temperature was 120°C, and the hydrothermal time was 10 h.

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