Preparation method and application of graphene-modified heterogeneous amorphous carbon

Abstract

A preparation method and application of graphene-modified heterogeneous amorphous carbon, belonging to the field of new materials. The specific scheme includes the following steps: adding the original material to the modifier, and obtaining the precursor material after microwave-assisted treatment under certain conditions. Adding the precursor material, the promoter and the graphene to the heterogeneous material, and obtaining the modified precursor after microwave-assisted treatment under certain conditions. The modified precursor is subjected to heat treatment in the presence of an inert gas to obtain graphene-modified heterogeneous amorphous carbon. The advantage of the present invention is that it provides a high-value-added utilization method for coal, and the preparation method is short in time, environmentally friendly, simple to operate, low in production cost and high in yield. The addition of graphene not only improves the conductivity of the material, but also inhibits the disordered growth of aromatic structures on the surface of the material. The prepared graphene-modified heterogeneous amorphous carbon material has excellent sodium ion battery performance.

Description

Technical Field

[0001] The present invention belongs to the field of new materials, and in particular relates to a preparation method and application of graphene-modified heterogeneous amorphous carbon. Background Art

[0002] With the rapid development of electrochemical energy storage technology, higher demands are being placed on it. The shortage and high cost of lithium resources have driven the rapid development of the sodium-ion battery industry. Sodium-ion batteries, with their advantages in resources and cost, are considered a complement to lithium-ion batteries and are considered an ideal device for large-scale energy storage. Therefore, the development and improvement of sodium-ion battery technology is of great practical significance. The performance of electrochemical energy storage systems depends primarily on the properties of electrode materials, and improving electrode material performance is an effective means of advancing electrochemical energy storage technology. The development of high-performance electrode materials is crucial for the commercial application of sodium-ion batteries. As a key component of sodium-ion batteries, the properties of the anode material have a significant impact on its performance. Regarding anode materials, the direct use of sodium metal as the anode in sodium-ion batteries is prohibited due to the hazardous nature of metallic sodium and the formation of sodium dendrites, which can easily lead to short circuits in liquid batteries and pose safety risks. Furthermore, graphite lacks the ability to store sodium due to its thermodynamic instability with sodium. Among the reported sodium-ion battery anode materials, amorphous carbon materials have become the most promising sodium-ion battery anode materials due to their relatively low sodium storage potential, high sodium storage capacity, and good cycling stability. Reported precursors for preparing amorphous carbon materials mainly include some biomass, polymers, resins, or organic chemicals. However, these precursors are relatively expensive, the preparation process is complex, and the carbon yield is low, which greatly restricts the large-scale application of amorphous carbon materials as sodium-ion battery anodes. Coal, as a common fossil energy source, is abundant, widely distributed, and inexpensive. In addition, because it is mainly composed of highly condensed aromatic structures and has a high carbon content, coal is an ideal precursor for preparing carbon materials. However, due to its highly condensed structure, its structure is difficult to control, which is not conducive to the storage of sodium ions.

[0003] Therefore, in order to address the shortcomings of the existing technology, the present invention uses cheap and easily available coal as raw material, combined with the excellent properties of graphene, to propose a simple, environmentally friendly and efficient method for preparing graphene-modified heterogeneous amorphous carbon. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing graphene-modified heterogeneous amorphous carbon and its application.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A preparation method of graphene-modified heterogeneous amorphous carbon, comprising the following steps:

[0007] Step 1: Mix the raw materials and the modifier evenly, and under a certain pressure, perform microwave-assisted treatment for a certain time, then wash, filter, and dry to obtain a precursor material; the raw materials include one or a combination of peat, lignite, bituminous coal, and anthracite, preferably bituminous coal; the modifier includes one or a combination of hydrogen peroxide, nitric acid, potassium permanganate, sodium hypochlorite, and manganese dioxide, preferably nitric acid;

[0008] Step 2: Add the precursor material, the promoter, and graphene to the heterogeneous material, stir well, and under a certain pressure, perform microwave-assisted treatment for a certain time, then wash, filter, and dry to obtain a modified precursor; the heterogeneous material includes one or a combination of coal tar, ethylene tar, and coal pitch, preferably coal tar;

[0009] Step 3: The modified precursor is heat-treated under an inert atmosphere to obtain graphene-modified heterogeneous amorphous carbon.

[0010] Furthermore, the mass ratio of the raw material to the modifier is 1-100:5, the mass ratio of the precursor material to graphene is 1-50:1, the mass ratio of the precursor material to the promoter is 1-100:5, and the mass ratio of the precursor material to the heterogeneous material is 1-200:10.

[0011] Furthermore, the molar concentration of the modifier hydrogen peroxide is 0.6-6 mol / L, and the molar concentration of nitric acid is 1-16 mol / L.

[0012] Furthermore, in Step 1, the pressure is 0.1-5 MPa, the microwave frequency is 10-10000 W, the microwave treatment time is 0.01-20 h, the drying temperature is 30-300 °C, and the drying time is 1-30 h; in Step 2, the pressure is 0.1-5 MPa, the microwave frequency is 10-10000 W, the microwave treatment time is 0.01-20 h, the drying temperature is 30-300 °C, and the drying time is 1-30 h.

[0013] Furthermore, the promoter includes one or a combination of sulfuric acid, phosphoric acid, oxalic acid, hydrochloric acid, and p-toluenesulfonic acid, preferably sulfuric acid.

[0014] Furthermore, the molar concentration of the promoter sulfuric acid is 1-18.4 mol / L, the molar concentration of phosphoric acid is 1-15 mol / L, the molar concentration of oxalic acid is 0.2-1.45 mol / L, and the molar concentration of hydrochloric acid is 1-12 mol / L.

[0015] Further, in step three, the inert atmosphere includes one or a combination of more of nitrogen, argon, and helium, and the flow rate of the inert gas is 0.1 - 10 L / min.

[0016] Further, in step three, the heat treatment temperature is 800 - 1600 °C, the heating rate is 1 - 20 °C / min; the heat treatment time is 0.1 - 20 h.

[0017] Graphene-modified heterogeneous amorphous carbon prepared by the described preparation method.

[0018] Further, the interlayer spacing d of the graphene-modified heterogeneous amorphous carbon 002 is 0.36 - 0.44 nm.

[0019] Application of graphene-modified heterogeneous amorphous carbon prepared by the described preparation method.

[0020] Further, the graphene-modified heterogeneous amorphous carbon is used as an electrode material for sodium ion batteries, lithium ion batteries, or potassium ion batteries.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] First, the present invention provides a method for high-value utilization of coal. The preparation method is time-consuming, environmentally friendly, simple to operate, low in production cost, and high in yield; second, the addition of graphene not only improves the conductivity of the material but also inhibits the disordered growth of the aromatic structure on the surface of the material; finally, the performance of the prepared graphene-modified heterogeneous amorphous carbon material for sodium ion batteries is effectively improved. Description of the Drawings

[0023] Figure 1 XRD spectra of samples YSCG1 and YSC1;

[0024] Figure 2 AC impedance spectra (left) and rate curves (right) of samples YSCG1 and YSC1;

[0025] Figure 3 SEM images of sample YSCG1 (left) and YSC1 (right). Detailed Embodiments

[0026] Hereinafter, the technical solutions in the present invention will be clearly and completely described in conjunction with the drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0027] Example 1

[0028] A method for preparing graphene-modified heterogeneous amorphous carbon comprises the following steps: adding 10 g of peat and 0.5 g of potassium permanganate into a 150 mL container at room temperature, thoroughly mixing, setting the pressure in the container to 5 MPa, treating the mixture at a microwave power of 10,000 W for 0.01 h, washing the mixture three times with deionized water, filtering the mixture, and drying the mixture at 100° C. for 6 h to obtain a precursor material A. 5 g of precursor material A, 25 g of p-toluenesulfonic acid and 0.1 g of graphene were added to 50 g of ethylene tar, mixed thoroughly, and added to a 150 ml container with a pressure of 0.1 MPa. The mixture was treated at a microwave power of 10 W for 20 h, washed three times with deionized water, filtered, and dried at 100 ° C for 6 h to obtain a modified precursor A. 2 g of modified precursor A was placed in a tube furnace and heated to 1300 ° C at a heating rate of 1 ° C / min in a nitrogen atmosphere of 0.1 L / min. After carbonization at 1300 ° C for 0.1 h, graphene-modified heterogeneous amorphous carbon was obtained, which was recorded as NSCG1.

[0029] Example 2

[0030] A method for preparing graphene-modified heterogeneous amorphous carbon comprises the following steps: adding 10 g of lignite and 50 g of 0.6 mol / L hydrogen peroxide into a 150 mL container at room temperature, mixing thoroughly, setting the pressure in the container to 2.5 MPa, treating the mixture at a microwave power of 5000 W for 3 min, washing three times with deionized water, filtering, and drying at 100° C. for 30 h to obtain a precursor material B. 5 g of precursor material B, 0.1 g of 15 mol / L phosphoric acid and 5 g of graphene were added to 0.5 g of coal tar, mixed thoroughly, and added to a 150 ml container. The pressure in the container was 0.5 MPa, and treated at a microwave power of 5000 W for 2 min. After washing three times with deionized water, it was filtered and dried at 100 ° C for 6 h to obtain a modified precursor B. 2 g of modified precursor B was taken in a tube furnace and heated to 1300 ° C at a heating rate of 5 ° C / min in a nitrogen atmosphere of 0.5 L / min. After carbonization at 1300 ° C for 20 h, graphene-modified heterogeneous amorphous carbon was obtained, which was recorded as HSCG1.

[0031] Example 3

[0032] A method for preparing graphene-modified heterogeneous amorphous carbon comprises the following steps: adding 10 g of bituminous coal and 5 g of 1 mol / L nitric acid into a 150 mL container at room temperature, thoroughly mixing, setting the pressure in the container to 1 MPa, treating the mixture at a microwave power of 500 W for 15 minutes, washing the mixture three times with deionized water, filtering the mixture, and drying the mixture at 100° C. for 6 hours to obtain a precursor material C. 5 g of precursor material C, 1 g of 18.4 mol / L sulfuric acid and 0.5 graphene were added to 50 g of coal tar, mixed thoroughly, and added to a 150 ml container. The pressure in the container was 0.5 MPa, and treated at a microwave power of 800 W for 20 min. After washing three times with deionized water, it was filtered and dried at 100 ° C for 6 h to obtain a modified precursor C. 2 g of modified precursor C was taken in a tubular furnace and heated to 1300 ° C at a heating rate of 5 ° C / min in a nitrogen atmosphere of 0.5 L / min. After carbonization at 1300 ° C for 3 h, graphene-modified heterogeneous amorphous carbon was obtained, which was recorded as YSCG1.

[0033] Example 4

[0034] A method for preparing graphene-modified heterogeneous amorphous carbon comprises the following steps: adding 10 g of anthracite and 1 g of sodium hypochlorite into a 150 mL container at room temperature, thoroughly mixing, setting the pressure in the container to 0.1 MPa, treating the mixture at a microwave power of 10 W for 10 h, washing the mixture three times with deionized water, filtering the mixture, and drying the mixture at 100° C. for 6 h to obtain a precursor material D. 5 g of precursor material D, 1 g of 1.45 mol / L oxalic acid and 0.2 g of graphene were added to 5 g of coal tar, mixed thoroughly, and added to a 150 ml container with a pressure of 2.5 MPa. The mixture was treated at a microwave power of 800 W for 30 min, washed three times with deionized water, filtered, and dried at 100 ° C for 6 h to obtain a modified precursor D. 2 g of modified precursor D was placed in a tube furnace and heated to 800 ° C at a heating rate of 10 ° C / min in a nitrogen atmosphere of 0.5 L / min. After carbonization at 800 ° C for 20 h, graphene-modified heterogeneous amorphous carbon was obtained, which was recorded as WSCG1.

[0035] Example 5

[0036] A method for preparing graphene-modified heterogeneous amorphous carbon comprises the following steps: adding 10 g of bituminous coal and 5 g of 1 mol / L nitric acid into a 150 mL container at room temperature, thoroughly mixing, setting the pressure in the container to 1 MPa, treating the mixture at a microwave power of 500 W for 15 minutes, washing the mixture three times with deionized water, filtering the mixture, and drying the mixture at 100° C. for 6 hours to obtain a precursor material C. 5 g of precursor material C and 1 g of 18.4 mol / L sulfuric acid were added to 50 g of coal tar, mixed thoroughly, and added to a 150 ml container with a pressure of 0.5 MPa. The mixture was treated at a microwave power of 800 W for 20 min, washed three times with deionized water, filtered, and dried at 100 ° C for 6 h to obtain a modified precursor E. 2 g of modified precursor E was placed in a tube furnace and heated to 1300 ° C at a heating rate of 5 ° C / min in a nitrogen atmosphere of 0.5 L / min. After carbonization at 1300 ° C for 3 h, a heterogeneous amorphous carbon was obtained, which was recorded as YSC1.

[0037] Table 1 Structural parameters of samples YSCG1 and YSC1

[0038]

[0039] The graphene-modified heterogeneous amorphous carbon prepared in Example 3 and the heterogeneous amorphous carbon prepared in Example 5 were subjected to structural characterization and electrochemical testing. Figure 1 The XRD spectra of samples YSCG1 and YSC1 show that the addition of graphene makes the material more disordered, which is consistent with the calculation results in Table 1. Samples YSCG1 and YSC1 were used as sodium ion battery electrode materials for electrochemical testing. The assembly and testing methods were carried out according to the reference [Energy & Fuels [J]. 2021, 35 (10): 9029-9037]. The electrochemical test results are shown in the attached Figure 2 As shown, it can be seen from the AC impedance spectrum on the left that the addition of graphene improves the conductivity of the material. From the rate test on the right, it can be seen that the addition of graphene improves the battery's first coulombic efficiency, specific capacity and rate performance. At a current density of 0.03A / g, the specific capacity can reach 316mAh / g, and the first coulombic efficiency is 80%. Figure 3 These are scanning electron microscope images of samples YSCG1 and YSC1. It can be seen from the image that the addition of graphene makes the material surface smoother and has fewer defects.

[0040] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A preparation method of graphene-modified heterogeneous amorphous carbon, characterized in that , including the following steps: Step 1: uniformly mixing the raw material and the modifier, subjecting them to microwave-assisted treatment under a certain pressure for a certain time, washing, filtering, and drying to obtain a precursor material; the raw material comprises a combination of one or more of peat, lignite, bituminous coal, and anthracite; and the modifier comprises a combination of one or more of hydrogen peroxide, nitric acid, potassium permanganate, sodium hypochlorite, and manganese dioxide; Step 2: adding the precursor material, the promoter and the graphene to the heterogeneous material, stirring the mixture thoroughly, and then subjecting the mixture to microwave-assisted treatment for a certain period of time under a certain pressure, washing, filtering and drying the mixture to obtain a modified precursor; the heterogeneous material comprises a combination of one or more of coal tar, ethylene tar and coal pitch; and the promoter comprises a combination of one or more of sulfuric acid, phosphoric acid, oxalic acid, hydrochloric acid and p-toluenesulfonic acid; Step three: The modified precursor is heat-treated under an inert atmosphere to obtain graphene-modified heterogeneous amorphous carbon; The mass ratio of the original material to the modifier is 1 to 100:5, the mass ratio of the precursor material to the graphene is 1 to 50:1, the mass ratio of the precursor material to the promoter is 1 to 100:5, and the mass ratio of the precursor material to the heterogeneous material is 1 to 200:

10.

2. The preparation method according to claim 1, characterized in that: In step 1, the pressure is 0.1-5MPa, the microwave frequency is 10-10000W, the microwave treatment time is 0.01 ~20h, the drying temperature is 30-300℃, and the drying time is 1-30h; in step 2, the pressure is 0.1-5MPa, the microwave frequency is 10-10000W, the microwave treatment time is 0.01 ~20h, the drying temperature is 30-300℃, and the drying time is 1-30h.

3. The preparation method according to claim 1, characterized in that: In step 3, the inert atmosphere includes a combination of one or more of nitrogen, argon and helium, and the inert gas flow rate is 0.1 to 10 L / min.

4. The preparation method according to claim 1, characterized in that: In step 3, the heat treatment temperature is 800-1600°C, the heating rate is 1-20°C / min, and the heat treatment time is 0.1-20h.

5. A graphene-modified heterogeneous amorphous carbon prepared by the preparation method according to any one of claims 1 to 4.

6. The graphene-modified heterogeneous amorphous carbon according to claim 5, wherein: The interlayer spacing d of the graphene-modified heterogeneous amorphous carbon 002 has a value of 0.36 - 0.44 nm.

7. Use of the graphene-modified heterogeneous amorphous carbon prepared by the preparation method according to any one of claims 1-4, characterized in that: The graphene-modified heterogeneous amorphous carbon is used as an electrode material for sodium ion batteries, lithium ion batteries or potassium ion batteries.

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