CN116573629B - Carbon superstructure material based on crystal splitting growth and self-assembly and preparation method thereof - Google Patents

Abstract

The present invention provides a carbon superstructure material based on crystal fission growth and self-assembly and a preparation method thereof. The preparation method comprises dissolving 4,4'-bipyridine, 3-aminobenzoic acid and Cu(NO ₃ ) ₂ ·3H ₂ O in a water/ethanol mixed solvent to generate a coordination effect to drive crystal fission growth and self-assembly polymerization reaction to generate a polymer superstructure, and then obtaining the carbon superstructure material after carbonization/nitric acid etching. The carbon superstructure material has a nanorod-like microscopic morphology, a high specific surface area, a hierarchical pore structure and abundant nitrogen/oxygen heteroatoms, can expose more active sites and provide a fast ion transmission rate, improve the transmission and diffusion kinetics of electrolyte ions in the material pores, and can be used as an ideal electrode material for supercapacitors. When the carbon superstructure material is used as an electrode material for a zinc ion hybrid supercapacitor, it exhibits excellent energy density and cycle life.

Description

Carbon superstructure material based on crystal splitting growth and self-assembly and preparation method thereof

Technical Field

The invention belongs to the technical field of material preparation, and in particular relates to a carbon superstructure material based on crystal splitting growth and self-assembly and a preparation method thereof.

Background Art

With the rapid development of modern society, energy crisis and environmental problems are becoming increasingly prominent, and the research and development of clean energy and renewable energy has become an inevitable trend. Among them, electrochemical energy storage devices have received great attention and development as clean energy to promote the realization of my country's "dual carbon" strategic goals. As a new type of energy storage device, aqueous zinc ion hybrid capacitors have attracted much attention due to the use of zinc metal negative electrodes with advantages such as high theoretical specific capacity, environmental friendliness and abundant resources, as well as economical, safe and environmentally friendly aqueous electrolytes. Carbon materials are regarded as highly potential positive electrode materials for efficient energy storage devices due to their structural diversity and functional adjustability, as well as their large specific surface area, high porosity, good conductivity, good chemical stability, abundant reserves and non-toxicity. Therefore, the development of new high-performance carbon electrode materials is one of the basic scientific and technological issues in designing aqueous zinc ion hybrid capacitors with both high energy density and high power density.

Low-dimensional carbon nanostructures are widely used in energy storage due to their favorable nano-sized structures. However, unstructured disordered aggregation greatly increases the resistance to electron transfer and structural instability, ultimately leading to poor energy storage performance of aqueous zinc ion hybrid capacitors. In order to overcome the defects of the above-mentioned existing low-dimensional carbon nanostructures, it is urgent to design a highly active and structurally stable carbon material to further improve the performance of zinc ion hybrid capacitors.

As a new type of carbon material, carbon superstructure materials are three-dimensional superstructure networks assembled from low-dimensional basic building blocks (such as nanoparticles, nanosheets, etc.). Carbon superstructures can not only maintain the basic properties of their building blocks, but also obtain additional multiple advantages, including more exposed surface active sites, developed internal pores, excellent skeleton stability, efficient charge transfer rate, etc. Therefore, through reasonable design, triggering the orderly spontaneous spatial nanoassembly of low-dimensional basic building blocks, thereby customizing "integrated" superstructure materials with a large curvature radius to enhance the kinetics of rapid ion migration and improve the high accessibility of electroactive sites, is crucial for comprehensively improving the electrochemical performance of aqueous zinc ion hybrid capacitors, but it is also quite challenging, especially using efficient and convenient preparation strategies.

Summary of the invention

The present invention is made to solve the above problems, and aims to provide a carbon superstructure material based on crystal splitting growth and self-assembly and a preparation method thereof.

The present invention provides a method for preparing a carbon superstructure material based on crystal splitting growth and self-assembly, which has the following characteristics and comprises the following steps:

Step S1, dissolving 4,4'-bipyridine, 3-aminobenzoic acid and Cu(NO ₃ ) ₂ ·3H ₂ O in a water/ethanol mixed solvent for reaction, and then filtering, washing and drying to obtain a polymer superstructure;

Step S2, after carbonizing the polymer superstructure under the protection of an inert gas, naturally cooling it to room temperature, soaking it in a nitric acid solution, and then washing and drying it to obtain a carbon superstructure material.

The method for preparing a carbon superstructure material based on crystal fission growth and self-assembly provided by the present invention may also have the following characteristics: wherein, in step S1, the mass ratio of 4,4'-bipyridine, 3-aminobenzoic acid, Cu( _NO3 ) ₂ · _3H2O and water/ethanol mixed solvent is 1:0.09-2.25:0.2-5:30-1000.

The method for preparing a carbon superstructure material based on crystal fission growth and self-assembly provided by the present invention may also have the following characteristics: wherein, in step S1, the volume ratio of water to ethanol in the water/ethanol mixed solvent is 1:1.

The method for preparing a carbon superstructure material based on crystal splitting growth and self-assembly provided by the present invention may also have the following characteristics: wherein, during the reaction in step S1, the reaction temperature is 10°C to 80°C, and the reaction time is 12h to 30h.

The method for preparing a carbon superstructure material based on crystal splitting growth and self-assembly provided by the present invention may also have the following characteristics: wherein, during carbonization in step S2, the carbonization temperature is 600°C to 1000°C, the carbonization time is 2h to 3h, and the heating rate when heated to the carbonization temperature is 2°C/min to 20°C/min.

The method for preparing the carbon superstructure material based on crystal fission growth and self-assembly provided by the present invention may also have the following characteristics: wherein, in step S2, the concentration of the nitric acid solution is 4M, and the soaking time is 12h to 72h.

The method for preparing a carbon superstructure material based on crystal fission growth and self-assembly provided by the present invention may also have the following characteristics: wherein, in step S2, the inert gas is nitrogen, argon or helium.

The method for preparing a carbon superstructure material based on crystal fission growth and self-assembly provided by the present invention may also have the following feature: wherein, in step S1 and step S2, ethanol is used for washing.

The present invention also provides a carbon superstructure material, which is prepared by the above-mentioned method for preparing the carbon superstructure material based on crystal splitting growth and self-assembly.

The present invention also provides a supercapacitor, the electrode material of which adopts the above-mentioned carbon superstructure material.

Functions and Effects of the Invention

According to a carbon superstructure material based on crystal fission growth and self-assembly and a preparation method thereof, 4,4'-bipyridine, 3-aminobenzoic acid and Cu( _NO3 ) ₂ · _3H2O are added to a water/ethanol mixed solvent to generate a polymer precursor by coordination, and the carbon superstructure material is obtained after carbonization and nitric acid etching.

The present invention uses a carbon superstructure material synthesized by a coordination compound of a specific type and ratio, which has a nanorod-like microscopic morphology, a high specific surface area, a hierarchical pore structure, and abundant nitrogen/oxygen heteroatoms, which can expose more active sites and provide a fast ion transmission rate, improve the transmission and diffusion dynamics of electrolyte ions in the material pores, and when the carbon superstructure material is used as a zinc ion hybrid supercapacitor electrode material, it exhibits excellent energy density and cycle life, and can be used as an ideal electrochemical energy storage electrode material. At the same time, the preparation raw materials of the present invention are widely available, low in cost and environmentally friendly, and the preparation process is simple and easy to operate, does not involve toxic and harmful reagents or high-pressure and high-temperature reaction conditions, and the polymerization reaction time is short.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a scanning electron microscope image of a carbon superstructure material prepared in Example 1 of the present invention;

FIG2 is a nitrogen adsorption-desorption isotherm of the carbon superstructure material prepared in Example 1 of the present invention;

FIG3 is an X-ray photoelectron spectrum of the carbon superstructure material prepared in Example 1 of the present invention;

FIG4 is a scanning electron microscope image of the carbon superstructure material prepared in Example 2 of the present invention;

FIG5 is a nitrogen adsorption-desorption isotherm of the carbon superstructure material prepared in Example 2 of the present invention;

FIG6 is an X-ray photoelectron spectrum of the carbon superstructure material prepared in Example 2 of the present invention;

FIG7 is a scanning electron microscope image of the carbon superstructure material prepared in Example 3 of the present invention;

FIG8 is a nitrogen adsorption-desorption isotherm of the carbon superstructure material prepared in Example 3 of the present invention;

FIG. 9 is an X-ray photoelectron spectrum of the carbon superstructure material prepared in Example 3 of the present invention.

DETAILED DESCRIPTION

In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the following embodiments and the accompanying drawings specifically illustrate the carbon superstructure material based on crystal splitting growth and self-assembly and the preparation method thereof.

<Example 1>

A method for preparing a carbon superstructure material based on crystal splitting growth and self-assembly in this embodiment includes the following steps:

Step S1, dissolving 4,4'-bipyridine, 3-aminobenzoic acid and Cu(NO ₃ ) ₂ ·3H ₂ O in a water/ethanol mixed solvent for reaction, and then filtering, washing and drying to obtain a polymer superstructure. The specific process is as follows:

4,4'-Bipyridine, 3-aminobenzoic acid, Cu(NO ₃ ) ₂ ·3H _{2 O and a water/ethanol (v/v=1:1) mixed solvent were weighed in sequence at a mass ratio of 1:0.45:1:153. 4,4'-Bipyridine, 3-aminobenzoic acid and Cu(NO 3 ) 2 ·3H 2} O were first dissolved in the water/ethanol mixed solvent, mixed evenly, reacted at 70°C for 24h, and then filtered, washed with ethanol and dried to obtain a polymer superstructure.

Step S2, after carbonizing the polymer superstructure under the protection of an inert gas, the polymer superstructure is naturally cooled to room temperature and immersed in a nitric acid solution, and then washed and dried to obtain a carbon superstructure material. The specific process is as follows:

The polymer superstructure was placed in a tubular furnace, and heated to 800°C at a heating rate of 10°C/min for carbonization under inert gas protection. The temperature was kept constant for 3 hours, and the temperature was naturally lowered to room temperature. The superstructure was then immersed in a 4M nitric acid solution for 48 hours. After washing with ethanol and drying, a carbon superstructure material was obtained.

FIG1 is a scanning electron microscope image of the carbon superstructure material prepared in Example 1 of the present invention; FIG2 is a nitrogen adsorption-desorption isotherm of the carbon superstructure material prepared in Example 1 of the present invention; FIG3 is an X-ray photoelectron spectrum of the carbon superstructure material prepared in Example 1 of the present invention.

As shown in Figures 1 to 3, the product prepared in this example is shown by scanning electron microscopy to be assembled from nanorod-like basic building blocks; nitrogen adsorption and desorption tests and X-ray photoelectron spectroscopy tests reveal that the product has a high specific surface area ( ^{658m2g -1} ) and abundant nitrogen/oxygen heteroatoms (9.37/5.54wt.%).

<Example 2>

A method for preparing a carbon superstructure material based on crystal splitting growth and self-assembly in this embodiment includes the following steps:

Step S1, dissolving 4,4'-bipyridine, 3-aminobenzoic acid and Cu(NO ₃ ) ₂ ·3H ₂ O in a water/ethanol mixed solvent for reaction, and then filtering, washing and drying to obtain a polymer superstructure. The specific process is as follows:

4,4'-Bipyridine, 3-aminobenzoic acid, Cu(NO ₃ ) ₂ ·3H ₂ O and a water/ethanol (v/v=1:1) mixed solvent were weighed in sequence at a mass ratio of 1:2.25:5:765. 4,4'-Bipyridine, 3-aminobenzoic acid and Cu(NO ₃ ) ₂ ·3H ₂ O were first dissolved in the water/ethanol mixed solvent, mixed evenly, reacted at 50°C for 24h, and then filtered, washed with ethanol and dried to obtain a polymer superstructure.

Step S2, after carbonizing the polymer superstructure under the protection of an inert gas, the polymer superstructure is naturally cooled to room temperature and immersed in a nitric acid solution, and then washed and dried to obtain a carbon superstructure material. The specific process is as follows:

The polymer superstructure was placed in a tubular furnace, and heated to 900°C at a heating rate of 5°C/min for carbonization under inert gas protection. The temperature was kept constant for 2 hours, and the temperature was naturally lowered to room temperature. The superstructure was then immersed in a 4M nitric acid solution for 12 hours. After washing with ethanol and drying, a carbon superstructure material was obtained.

Figure 4 is a scanning electron microscope image of the carbon superstructure material prepared in Example 2 of the present invention; Figure 5 is a nitrogen adsorption-desorption isotherm of the carbon superstructure material prepared in Example 2 of the present invention; Figure 6 is an X-ray photoelectron spectrum of the carbon superstructure material prepared in Example 2 of the present invention.

As shown in Figures 4 to 6, the product prepared in this example is shown by scanning electron microscopy to be assembled from nanorod-like basic building blocks; nitrogen adsorption and desorption tests and X-ray photoelectron spectroscopy tests reveal that the product has a high specific surface area ( ^{424m2g -1} ) and abundant nitrogen/oxygen heteroatoms (8.04/5.98wt.%).

<Example 3>

A method for preparing a carbon superstructure material based on crystal splitting growth and self-assembly in this embodiment includes the following steps:

Step S1, dissolving 4,4'-bipyridine, 3-aminobenzoic acid and Cu(NO ₃ ) ₂ ·3H ₂ O in a water/ethanol mixed solvent for reaction, and then filtering, washing and drying to obtain a polymer superstructure. The specific process is as follows:

4,4'-bipyridine, 3-aminobenzoic acid, Cu(NO ₃ ) ₂ ·3H ₂ O and a water/ethanol (v/v=1:1) mixed solvent were weighed in sequence at a mass ratio of 1:0.09:0.2:30. 4,4'-bipyridine, 3-aminobenzoic acid and Cu(NO ₃ ) ₂ ·3H ₂ O were first dissolved in the water/ethanol mixed solvent, mixed evenly, reacted at 70°C for 30h, and then filtered, washed with ethanol and dried to obtain a polymer superstructure.

Step S2, after carbonizing the polymer superstructure under the protection of an inert gas, the polymer superstructure is naturally cooled to room temperature and immersed in a nitric acid solution, and then washed and dried to obtain a carbon superstructure material. The specific process is as follows:

The polymer superstructure was placed in a tubular furnace, and heated to 700°C at a heating rate of 2°C/min for carbonization under inert gas protection. The temperature was kept constant for 2 hours, and the temperature was naturally lowered to room temperature. The superstructure was then immersed in a 4M nitric acid solution for 48 hours. After washing with ethanol and drying, a carbon superstructure material was obtained.

Figure 7 is a scanning electron microscope image of the carbon superstructure material prepared in Example 3 of the present invention; Figure 8 is a nitrogen adsorption-desorption isotherm of the carbon superstructure material prepared in Example 3 of the present invention; Figure 9 is an X-ray photoelectron spectrum of the carbon superstructure material prepared in Example 3 of the present invention.

As shown in Figures 7 to 9, the product prepared in this example is shown by scanning electron microscopy to be assembled from nanorod-like basic building blocks; nitrogen adsorption and desorption tests and X-ray photoelectron spectroscopy tests reveal that the product has a high specific surface area (539 ^m2 g ^-1 ) and abundant nitrogen/oxygen heteroatoms (7.24/6.72 wt.%).

<Example 4>

In this embodiment, the carbon superstructure material prepared in Embodiments 1 to 3 is used as an electrode material to prepare a supercapacitor, and the specific preparation process is as follows:

The carbon superstructure material prepared in Example 1, 2 or 3, 60wt% polytetrafluoroethylene emulsion (purchased from Shanghai San Ai Fu New Materials Co., Ltd.), and graphite were mixed evenly (wherein, the mass ratio of carbon superstructure material, 60wt% polytetrafluoroethylene emulsion and graphite was 8:1:1), placed in an oven for drying, and the dried sample was pressed on a stainless steel mesh (purchased from Jiangsu Ningcong Wire Mesh) under a pressure of 20MPa, and vacuum dried at 100°C for 24h to prepare a working electrode. A CR2032 button battery shell was selected, the prepared working electrode was used as the positive electrode, a metal zinc sheet (purity ≥99.99%) was used as the negative electrode, a GE-Whatman glass fiber diaphragm was used, and a 2mol/L Zn(SO ₄ ) ₂ solution was selected as the electrolyte to assemble a zinc ion hybrid supercapacitor.

The device energy storage performance was tested using a CHI660E electrochemical workstation. The test results are as follows:

The energy density of the working electrodes (Examples 1, 2, and 3) is above 150Whkg ^-1 , and the capacity retention rate after 300,000 cycles of charge and discharge is above 90%, showing excellent energy density and outstanding cycle life.

Functions and Effects of the Embodiments

According to the first to third embodiments, compared with the reported superstructure materials composed of basic building blocks such as nanoparticles and nanosheets, the carbon superstructure material synthesized by using a coordination compound of a specific type and ratio in the present invention is assembled from nanorod-like basic building blocks, has a high specific surface area (424-658m ² g ^-1 ) and rich nitrogen/oxygen heteroatom doping amounts (7.24-9.37/5.54-6.72wt.%), and the nanorod-like morphology is exquisite, has well-developed internal pores, and has high thermal stability. The unique microstructure makes the carbon superstructure material of the present invention an ideal candidate for supporting high-efficiency energy storage applications.

According to Example 4, the zinc ion hybrid capacitor assembled using the carbon superstructure material prepared by the present invention as the electrode material has an ultra-high energy density (157Wh kg ^-1 ) and excellent cycle capacity, and the capacity retention rate after 300,000 cycles of charge and discharge is above 90%. Thanks to the carbon superstructure material of the present invention exposing more active sites and convenient ion transmission channels, the transmission and diffusion dynamics of electrolyte ions in the material pores are improved, thus showing ultra-high specific capacity and excellent cycle stability.

At the same time, the raw materials for the preparation of the present invention are widely available, low in cost and environmentally friendly, and the preparation process is simple and easy to operate, does not involve toxic and harmful reagents or high-pressure and high-temperature reaction conditions, and the polymerization reaction time is short.

The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.

Claims (8)

1. A method for preparing a carbon superstructure material based on crystal splitting growth and self-assembly, characterized in that it comprises the following steps: Step S1, dissolving 4,4'-bipyridine, 3-aminobenzoic acid and Cu(NO ₃ ) ₂ ·3H ₂ O in a water/ethanol mixed solvent for reaction, and then filtering, washing and drying to obtain a polymer superstructure; Step S2, after carbonizing the polymer superstructure under the protection of an inert gas, naturally cooling it to room temperature, soaking it in a nitric acid solution, and then washing and drying it to obtain a carbon superstructure material. Wherein, in step S1, the mass ratio of 4,4'-bipyridine, 3-aminobenzoic acid, Cu(NO ₃ ) ₂ ·3H ₂ O and water/ethanol mixed solvent is 1:0.09-2.25:0.2-5:30-1000, When the reaction is carried out in step S1, the reaction temperature is 10° C. to 80° C., and the reaction time is 12 h to 30 h. 2. The method for preparing a carbon superstructure material based on crystal splitting growth and self-assembly according to claim 1, characterized in that: Wherein, in step S1, the volume ratio of water to ethanol in the water/ethanol mixed solvent is 1:1. 3. The method for preparing a carbon superstructure material based on crystal splitting growth and self-assembly according to claim 1, characterized in that: Wherein, when carbonization is performed in step S2, the carbonization temperature is 600°C to 1000°C, the carbonization time is 2h to 3h, and the heating rate when heated to the carbonization temperature is 2°C/min to 20°C/min. 4. The method for preparing a carbon superstructure material based on crystal fission growth and self-assembly according to claim 1, characterized in that: Wherein, in step S2, the concentration of the nitric acid solution is 4M, and the soaking time is 12h to 72h. 5. The method for preparing a carbon superstructure material based on crystal fission growth and self-assembly according to claim 1, characterized in that: Wherein, in step S2, the inert gas is nitrogen, argon or helium. 6. The method for preparing a carbon superstructure material based on crystal fission growth and self-assembly according to claim 1, characterized in that: Wherein, in step S1 and step S2, ethanol is used for washing. 7. A carbon superstructure material, characterized in that it is prepared by the method for preparing a carbon superstructure material based on crystal fission growth and self-assembly as described in any one of claims 1 to 6. 8. A supercapacitor, characterized in that the electrode material of the supercapacitor is the carbon superstructure material according to claim 7.