CN116395678A - 3D graphene and preparation method thereof - Google Patents

3D graphene and preparation method thereof Download PDF

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CN116395678A
CN116395678A CN202310509706.XA CN202310509706A CN116395678A CN 116395678 A CN116395678 A CN 116395678A CN 202310509706 A CN202310509706 A CN 202310509706A CN 116395678 A CN116395678 A CN 116395678A
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graphene
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heating
mesoporous silica
diameter
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刘静
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Svolt Energy Technology Maanshan Co Ltd
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    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00Carbon; Compounds thereof
    • C01B32/15Nano-sized carbon materials
    • C01B32/182Graphene
    • C01B32/184Preparation
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    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00Carbon; Compounds thereof
    • C01B32/15Nano-sized carbon materials
    • C01B32/182Graphene
    • C01B32/194After-treatment
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2204/00Structure or properties of graphene
    • C01B2204/20Graphene characterized by its properties
    • C01B2204/22Electronic properties
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2204/00Structure or properties of graphene
    • C01B2204/20Graphene characterized by its properties
    • C01B2204/26Mechanical properties
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Abstract

A3D graphene and a preparation method thereof belong to the technical field of lithium ion battery anode materials and overcome the defect of poor mechanical strength of graphene. The 3D graphene is a network structure formed by nano rods; the diameter of the nano rod is 100-400 nm; a mesoporous is formed on the nano rod; the network structure has pores with a diameter of 3-6 μm. The 3D graphene provided by the invention has a multi-level pore structure, so that the compressive strength of the 3D graphene can be improved, the elasticity is good, the compressive strength is high, and the multi-level pore structure can help to expose more active sites, thereby being beneficial to interaction with lithium ions.

Description

3D graphene and preparation method thereof
Technical Field
The invention belongs to the technical field of lithium ion battery anode materials, and particularly relates to 3D graphene and a preparation method thereof.
Background
Carbon is the most commonly used material in electrochemical energy storage devices, and in commercial Lithium Ion Batteries (LIB), lithium ion intercalated graphite is used as the anode material, while the cathode contains carbon black or the like to improve the conductivity of the material. Carbon materials have also been extensively explored in research, either as high performance electrodes per se or in combination with other electrode materials to form composite electrodes, such as LiFePO 4 and/C positive electrode.
Graphene is a functional material that has emerged in recent years, and studies have shown that pristine and heteroatom doped graphene materials have higher capacities than commercial graphite cathodes. Fewer layers of graphene may have a higher capacity than bulk graphite, for example: lian et al uses the Hummer method to exfoliate graphite into graphene sheets for use in forming LIB anodes, the material being at 100mAg -1 Is (1) the current of the (a)The battery capacity after 40 times of circulation under the density is 848mAh g -1 Is obviously higher than 375mAh g of graphite cathode -1
However, the existing graphene and heteroatom doped graphene have poor mechanical strength, are difficult to bear compression, and prevent practical application.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defect of poor mechanical strength of graphene, so as to provide 3D graphene and a preparation method thereof.
For this purpose, the invention provides the following technical scheme.
In a first aspect, the invention discloses 3D graphene, wherein the 3D graphene is a network structure formed by nanorods;
the diameter of the nano rod is 100-400 nm; a mesoporous is formed on the nano rod;
the network structure has pores with a diameter of 3-6 μm.
The holes of the network structure are continuous pores, the skeletons are connected in a staggered way, and the holes are continuous in SEM images.
In one possible design, the network structure has pores with diameters of 3-5 μm, and the nanorods have mesopores with diameters of 1-7 nm formed thereon;
optionally, the specific surface area of the 3D graphene is 800-1200 m 2 g -1
In one possible design, the 3D graphene is an N-doped 3D graphene, the network structure has pores with diameters of 4-6 μm, and the nanorods have mesopores with diameters of 2-6 nm formed thereon;
optionally, the doping amount of N is 3-5 wt%;
optionally, the specific surface area of the N-doped 3D graphene is 500-800 m 2 g -1
In one possible design, the 3D graphene is a B-N doped 3D graphene, the network structure has pores with diameters of 4-6 μm, and the nanorods have mesopores with diameters of 2-6 nm formed thereon;
optionally, mesoporous with the diameter of 10-30 nm is formed on the surface of the nano rod;
optionally, the doping amount of N is 1-2 wt%, and the doping amount of B is 0.3-0.6 wt%;
optionally, the specific surface area of the B-N doped 3D graphene is 450-600 m 2 g -1
In a second aspect, the present invention provides a method for preparing the 3D graphene, including: graphene is grown on mesoporous silica, and then the mesoporous silica is removed.
Further, growing graphene on mesoporous silica includes:
step 1, ar and H with flow rates of 280-320 sccm and 40-60 sccm are used respectively 2 Flushing a tubular furnace with mesoporous silica inside for 10-30 min;
step 2, heating the tube furnace to 750-850 ℃ and preserving heat for 30min; continuously introducing a carbon source at a flow rate of 10-30 sccm in the heating and heat preservation processes, and growing graphene by using a vapor deposition technology; then heating the tube furnace to 1050-1150 ℃, preserving heat for 40-80 min, and finally stopping introducing the carbon source.
Further, the carbon source is CH 4 、C 2 H 6 Or C 3 H 8 Preferably, the flow rate of the carbon source is 15 to 25sccm.
In one possible design, the 3D graphene is an N-doped 3D graphene, and growing graphene on mesoporous silica includes:
step 1', adopting Ar to carry a carbon source and a nitrogen source at the flow rate of 80-120 sccm to flush a tubular furnace with mesoporous silica inside for 10-30 min at room temperature;
and 2', heating the tube furnace to 1050-1150 ℃ within 80min, continuously introducing Ar carrying a carbon source and a nitrogen source at the flow rate in the step 1' in the heating process, heating to 1050-1150 ℃, preserving heat for 10-30 min, and finally stopping introducing the gas.
Optionally, the 3D graphene is an N-doped 3D graphene, and when the graphene is grown on mesoporous silica, the carbon source in step 1 is a liquid carbon source containing N, for example, pyruvonitrile, and the nitrogen source is exemplified by N, N-Dimethylformamide (DMF). The carbon source containing N is used for introducing N atoms in situ while generating graphene, so as to realize in-situ N doping; and N, N-dimethylformamide as another N source can help to regulate N type in N-doped 3D graphene.
In one possible design, the 3D graphene is a B-N doped 3D graphene, and growing graphene on mesoporous silica includes:
step 1", flushing a tubular furnace with mesoporous silica inside by Ar at the flow rate of 80-120 sccm with a carbon source, a nitrogen source and a boron source for 10-30 min at room temperature;
and 2', heating the tube furnace to 1050-1150 ℃ within 80min, continuously introducing Ar gas carrying a carbon source, a nitrogen source and a boron source at the flow rate in the step 1″ in the heating process, heating to 1050-1150 ℃, preserving heat for 10-30 min, and finally stopping introducing the gas.
Further, the preparation method of the mesoporous silica comprises the following steps:
(1) Mixing a surfactant, water and acid, adding a silicon source, and stirring to obtain sol;
alternatively, the acid is HCl, H 2 SO 4 Or H 3 PO 4 At least one of (a) and (b);
(2) Transferring the sol into an autoclave, heating the autoclave to 120-150 ℃ for hydrothermal reaction for 24-48 hours;
(3) And drying and calcining to obtain the mesoporous silica.
The technical scheme of the invention has the following advantages:
1. the 3D graphene provided by the invention is a network structure formed by nano rods; the diameter of the nano rod is 100-400 nm; a mesoporous is formed on the nano rod; the network structure has pores with a diameter of 3-6 μm.
The 3D graphene provided by the invention has a hierarchical pore structure, not only has a large number of continuous pores in a network structure, but also has mesopores of the nanorods, so that the compressive strength of the 3D graphene can be improved, the 3D graphene can be compressed under a certain pressure, and the 3D graphene can be restored to the original shape after the pressure is relieved, and the 3D graphene has good elasticity and high compressive strength. And the hierarchical pore structure can help expose more active sites, facilitating interactions with lithium ions.
2. The 3D graphene provided by the invention is N-doped 3D graphene, the network structure is provided with continuous pores with the diameter of 4-6 mu m, and the nanorods are provided with pores with the diameter of 2-6 nm; the doping amount of N is 3wt percent to 5wt percent. The B-N doped 3D graphene has high capacity, high rate performance, cycle stability and ultrahigh elasticity.
3. According to the preparation method of the 3D graphene, the problem of uneven material dispersion (gas-solid reaction, more sufficient contact) can be well solved by adopting a chemical vapor deposition method, so that the uniformity of the prepared product is better.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a scanning electron microscope image of 3D graphene prepared in example 1;
fig. 2 is a graph of nitrogen adsorption/desorption curve (upper right corner of fig. 2) and pore size distribution of the 3D graphene prepared in example 1; p is absolute pressure, P 0 Is saturated steam pressure; saturated steam pressure P 0 : at a given temperature, the pressure at which a gas liquefies, i.e., the pressure at which nitrogen liquefies, is cooled by liquid nitrogen.
FIG. 3 is a scanning electron microscope image of N-doped 3D graphene prepared in example 2;
FIG. 4 is a high resolution X-ray photoelectron spectrum of N1s of the N-doped 3D graphene prepared in example 2;
fig. 5 is a nitrogen adsorption/desorption curve (upper right corner of fig. 5) and a pore size distribution diagram of the N-doped 3D graphene prepared in example 2.
FIG. 6 is a scanning electron microscope image of the B-N doped 3D graphene prepared in example 3;
FIG. 7 is a high-resolution N1s spectrum and a high-resolution B1s spectrum of the B-N doped 3D graphene prepared in example 3;
FIG. 8 is a graph of nitrogen adsorption/desorption curves (upper right corner of FIG. 8) and pore size distribution of the B-N doped 3D graphene prepared in example 3;
FIG. 9 is a stress-strain curve of the 3D graphene prepared in example 1;
FIG. 10 is a stress-strain curve of N-doped 3D graphene prepared in example 2;
FIG. 11 is a stress-strain curve of the B-N doped 3D graphene prepared in example 3;
fig. 12 shows the rate performance of the 3D graphene prepared in examples 1, 2, and 3;
FIG. 13 shows that 3D graphene prepared in examples 1, 2 and 3 is 1Ag -1 Specific capacity versus cycle number at current density.
Detailed Description
The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.
Example 1
The embodiment provides a preparation method of 3D graphene, which comprises the following steps:
(1) Preparing mesoporous silicon dioxide:
1.286g of surfactant Pluronic block copolymer (P123, sigma Aldrich, mw=5800) was first dissolved in 50mL of distilled water, then 7.14mL of HCl solution (12 mol/L HCl concentration) was added, then Si source tetraethyl silicate (TEOS, ARCOS) was added, and after stirring at 1000 revolutions per minute for 30 minutes, the resulting sol was transferred to an autoclave lined with PTFE. The hydrothermal reaction was carried out by heating the autoclave to 130 ℃ and then holding for 36 hours. And then drying and heating to 550 ℃ at 1 ℃/min for calcination for 6 hours to obtain the silicon dioxide with the mesoporous ordered structure.
(2) Graphene growth on mesoporous silica:
ar and H were first used at flow rates of 300sccm and 50sccm, respectively 2 The tube furnace with silica inside was rinsed for 20min.
Heating the furnace to 800 ℃ within 50 minutes, and preserving the heat at 800 ℃ for 30 minutes, continuously introducing a carbon source at a flow rate of 20sccm during the heating and preserving, and using a vapor deposition (CVD) technology to generate feldspar graphene, wherein the carbon source is CH in the embodiment 4 . And after the temperature is continuously raised to 1100 ℃, preserving the heat for 60 minutes at the temperature of 1100 ℃, and finally stopping introducing the carbon source.
(3) And after the reaction is finished, etching and removing mesoporous silica in the product by using hydrofluoric acid to obtain the 3D graphene.
Example 2
The embodiment provides a preparation method of 3D graphene, wherein the 3D graphene is N-doped 3D graphene, and the preparation method comprises the following steps:
(1) Preparing mesoporous silicon dioxide:
1.286g of surfactant Pluronic block copolymer (P123, sigma Aldrich, mw=5800) was first dissolved in 50mL of distilled water, then 7.14mL of HCl solution (12 mol/L HCl concentration) was added, then Si source tetraethyl silicate (TEOS, ARCOS) was added, and after stirring at 1000 revolutions per minute for 30 minutes, the resulting sol was transferred to an autoclave lined with PTFE. The hydrothermal reaction was carried out by heating the autoclave to 130 ℃ and then holding for 36 hours. And then drying and heating to 550 ℃ at 1 ℃/min for calcination for 6 hours to obtain the silicon dioxide with the mesoporous ordered structure.
(2) Graphene growth on mesoporous silica:
the tube furnace with mesoporous silica inside was flushed with Ar at a flow rate of 100sccm with pyruvonitrile (Alfa Aesar) and N, N dimethylformamide (DMF, alfa Aesar) for 20min. The volume ratio of the pyruvonitrile to the N, N-dimethylformamide is 8:2.
Heating the tubular furnace to 1100 ℃ within 80 minutes, continuously introducing Ar carrying the pyruvonitrile and the DMF at a flow rate of 100sccm in the heating process, heating to 1100 ℃, preserving heat for 20 minutes, and finally stopping introducing the air flow.
(3) And after the reaction is finished, etching and removing mesoporous silica in the product by using hydrofluoric acid to obtain the N-doped 3D graphene.
Example 3
The embodiment provides a preparation method of 3D graphene, wherein the 3D graphene is B-N doped 3D graphene, and the preparation method comprises the following steps:
(1) Preparing mesoporous silicon dioxide:
1.286g of surfactant Pluronic block copolymer (P123, sigma Aldrich, mw=5800) was first dissolved in 50mL of distilled water, then 7.14mL of HCl solution (12 mol/L HCl concentration) was added, then Si source tetraethyl silicate (TEOS, ARCOS) was added, and after stirring at 1000 revolutions per minute for 30 minutes, the resulting sol was transferred to an autoclave lined with PTFE. The hydrothermal reaction was carried out by heating the autoclave to 130 ℃ and then holding for 36 hours. And then drying and heating to 550 ℃ at 1 ℃/min for calcination for 6 hours to obtain the silicon dioxide with the mesoporous ordered structure.
(2) Graphene growth on mesoporous silica:
at room temperature, ar is used for carrying boric acid and pyridine at a flow rate of 100sccm to flush a tubular furnace with mesoporous silica inside for 20min. The concentration of boric acid in pyridine was 8mol/L.
The furnace was warmed to 1100 ℃ for 20 minutes, and during the warming, the Ar carrying boric acid and pyridine was continuously introduced at a flow rate of 100sccm, and after warming to 1100 ℃, the temperature was maintained for 20 minutes, and finally the introduction of the air stream was stopped.
(3) And after the reaction is finished, etching and removing mesoporous silica in the product by using hydrofluoric acid to obtain the B-N doped 3D graphene.
Example 4
The embodiment provides a preparation method of 3D graphene, which comprises the following steps:
(1) Preparing mesoporous silicon dioxide:
1.286g of surfactant Pluronic block copolymer (P123, sigma Aldrich, mw=5800) was first dissolved in 50mL of distilled water, then 7.14mL of HCl solution (12 mol/L HCl concentration) was added, then Si source tetraethyl silicate (TEOS, ARCOS) was added, and after stirring at 1000 revolutions per minute for 30 minutes, the resulting sol was transferred to an autoclave lined with PTFE. The hydrothermal reaction was carried out by heating the autoclave to 130 ℃ and then holding for 36 hours. And then drying and heating to 550 ℃ at 1 ℃/min for calcination for 6 hours to obtain the silicon dioxide with the mesoporous ordered structure.
(2) Graphene growth on mesoporous silica:
ar and H were first used at flow rates of 280sccm and 40sccm, respectively 2 The tube furnace with silica inside was rinsed for 20min.
Raising the furnace temperature to 750 ℃ within 50 minutes, and preserving the heat at 750 ℃ for 30 minutes, continuously introducing a carbon source at a flow rate of 25sccm during the heating and preserving, and using a vapor deposition (CVD) technology to generate feldspar graphene, wherein the carbon source is C in the embodiment 2 H 6 . After the temperature is continuously raised to 1050 ℃, the temperature is kept at 1050 ℃ for 70 minutes, and finally, the carbon source is stopped being introduced.
(3) And after the reaction is finished, etching and removing mesoporous silica in the product by using hydrofluoric acid to obtain the 3D graphene.
Example 5
The embodiment provides a preparation method of 3D graphene, wherein the 3D graphene is N-doped 3D graphene, and the preparation method comprises the following steps:
(1) Preparing mesoporous silicon dioxide:
1.286g of surfactant Pluronic block copolymer (P123, sigma Aldrich, mw=5800) was first dissolved in 50mL of distilled water, then 7.14mL of HCl solution (12 mol/L HCl concentration) was added, then Si source tetraethyl silicate (TEOS, ARCOS) was added, and after stirring at 1000 revolutions per minute for 30 minutes, the resulting sol was transferred to an autoclave lined with PTFE. The hydrothermal reaction was carried out by heating the autoclave to 150 ℃ and then holding for 24 hours. And then drying and heating to 550 ℃ at 1 ℃/min for calcination for 6 hours to obtain the silicon dioxide with the mesoporous ordered structure.
(2) Graphene growth on mesoporous silica:
the tube furnace with mesoporous silica inside was flushed with Ar at 80sccm flow rate with pyruvonitrile (Alfa Aesar) and N, N dimethylformamide (DMF, alfa Aesar) for 30min. The volume ratio of the pyruvonitrile to the N, N-dimethylformamide is 8:2.
Heating the tubular furnace to 1150 ℃ within 80 minutes, continuously introducing Ar carrying the pyruvonitrile and DMF at a flow rate of 80sccm in the heating process, heating to 1150 ℃ and preserving heat for 10 minutes, and finally stopping introducing the air flow.
(3) And after the reaction is finished, etching and removing mesoporous silica in the product by using hydrofluoric acid to obtain the N-doped 3D graphene.
Example 6
The embodiment provides a preparation method of 3D graphene, wherein the 3D graphene is B-N doped 3D graphene, and the preparation method comprises the following steps:
(1) Preparing mesoporous silicon dioxide:
1.286g of surfactant Pluronic block copolymer (P123, sigma Aldrich, mw=5800) was first dissolved in 50mL of distilled water, then 7.14mL of HCl solution (12 mol/L HCl concentration) was added, then Si source tetraethyl silicate (TEOS, ARCOS) was added, and after stirring at 1000 revolutions per minute for 30 minutes, the resulting sol was transferred to an autoclave lined with PTFE. The hydrothermal reaction was carried out by heating the autoclave to 120 ℃ and then holding for 48 hours. And then drying and heating to 550 ℃ at 1 ℃/min for calcination for 6 hours to obtain the silicon dioxide with the mesoporous ordered structure.
(2) Graphene growth on mesoporous silica:
at room temperature, the tube furnace with silica inside was rinsed with Ar carrying boric acid and pyridine at a flow rate of 120sccm for 10min. The concentration of boric acid in pyridine was 8mol/L.
The furnace was warmed to 1050 ℃ for 30 minutes, and during the warming, the Ar carrying boric acid and pyridine was continuously fed at a flow rate of 120sccm, and after warming to 1050 ℃, the temperature was maintained for 20 minutes, and finally the feeding of the air stream was stopped.
(3) And after the reaction is finished, etching and removing mesoporous silica in the product by using hydrofluoric acid to obtain the B-N doped 3D graphene.
Fig. 1 is a Scanning Electron Microscope (SEM) image of the 3D graphene prepared in example 1. As can be seen from fig. 1, the 3D graphene exhibits a hierarchical pore structure consisting of nanorods with diameters of 100 to 400nm, with continuous pores with diameters of 3 to 5 μm.
Fig. 2 is a graph showing nitrogen adsorption/desorption curves and pore size distribution diagrams of the 3D graphene prepared in example 1. As can be seen from FIG. 2, 3D graphene has pores with sizes of 1nm and 3-6nm, and a specific surface area as high as 1035m 2 g -1
Fig. 3 is a Scanning Electron Microscope (SEM) image of the N-doped 3D graphene prepared in example 2. As can be seen from fig. 3, the N-doped 3D graphene consists of nanorods with a diameter of 100 to 400nm, with continuous pores with a diameter of 4 to 6 μm.
Fig. 4 is a high resolution X-ray photoelectron spectrum of N1s of the N-doped 3D graphene prepared in example 2. The high resolution N1s spectra can be divided into 401.2eV, 400.1eV and 398.2eV, corresponding to graphite N, pyridine N and pyrrole N, respectively. The N content was 4.92%, and the percentages of graphite N, pyrrole N and pyridine N in the N atoms were 85.9%, 3.8% and 10.2%, respectively. Fig. 4 illustrates that N was successfully doped into 3D graphene while the content of different types of nitrogen was analyzed.
Fig. 5 is a graph showing nitrogen adsorption/desorption curves and pore size distribution diagrams of the N-doped 3D graphene prepared in example 2. As can be seen from FIG. 5, there are no pores smaller than 2nm in the N-doped 3D graphene, the pore diameter of the N-doped 3D graphene is 2-6 nm, and the specific surface area thereof is 637m 2 g -1 . Fig. 5 illustrates that N-doped 3D graphene maintains a hierarchical pore structure and a higher specific surface area when undoped.
Fig. 6 is a Scanning Electron Microscope (SEM) image of the B-N doped 3D graphene prepared in example 3. The B-N doped 3D graphene consists of nanorods with the diameter of 100-400nm and has continuous pores with the diameter of 4-6 mu m.
FIG. 7 is a diagram ofThe high resolution N1s spectrum and the high resolution B1s spectrum of the B-N doped 3D graphene prepared in example 3. High resolution N1s indicates that the peaks of 401.5eV, 400.0eV and 398.1eV correspond to graphite N, pyridine N and pyrrole N. Furthermore, the peak at 398.9eV indicates that N (C-N-B) is linked to C and B. The N content was 1.64%, and the percentages of graphite N, pyrrole N, pyridine N and C-N-B in the N atoms were 59.3%, 17.0%, 14.0% and 9.7%, respectively. The B1s XPS spectra showed three characteristic peaks at 189.0eV, 190.9eV and 192.9eV, corresponding to boron bonds between carbon atoms (BC 3 ) Bonding of boron to N atom (B-N and bonding of boron to carbon and oxygen atom (BC) 2 O and BCO 2 ) The content of B was 0.41at%.
Fig. 8 is a nitrogen adsorption/desorption curve and pore size distribution diagram of the B-N doped 3D graphene prepared in example 3. Adsorption and desorption isotherms of the B-N doped 3D graphene show that the pore diameter is 2-6 nm, and the specific surface area is 610m 2 g -1
Test examples
(1) Compression test of 3D graphene prepared in examples 1 to 3: rectangular samples with an aspect ratio of 0.8 were used, using a single column mechanical test system (Instron-5566), at a constant loading speed of 2mm min -1 And (5) running downwards.
Fig. 9 is a stress-strain curve of the 3D graphene prepared in example 1. As can be seen from fig. 9, the reversible deformation of the 3D graphene prepared in example 1 is characterized by a higher young's modulus for unloading than for loading, and the young's modulus for unloading and the young's modulus for loading at 0-30% strain are 0.31MPa and 0.17MPa, respectively. After 30% to 90% deformation, plastic deformation still did not occur, indicating excellent elasticity.
Fig. 10 and 11 are stress-strain curves of the N-doped 3D graphene prepared in example 2 and the B-N-doped 3D graphene prepared in example 3, respectively.
The N-doped and N-B co-doped 3D graphene completely recover to an initial state after unloading. The modulus of the N-doped 3D graphene is 0.8MPa when the graphene is unloaded, and the modulus of the N-doped 3D graphene is 0.52MPa when the graphene is loaded; the modulus of the N-B co-doped 3D graphene is 0.386MPa when unloaded and 0.265MPa when loaded.
The 3D graphene has a multistage pore structure, a large number of continuous pores, very low solid fraction, hollow characteristics of the nano tube and low Young's modulus, and can be compressed under a certain pressure, and can be restored to the original shape after the pressure is relieved, so that the 3D graphene has good elasticity and high compressive strength.
(2) The electrochemical performance of the 3D graphene prepared in examples 1-3 was tested by: cutting 3D graphene into discs, directly using the discs as a working electrode (anode), using a polyacrylonitrile membrane (Celgard) as a diaphragm, using a lithium sheet as a cathode, wherein the amount of 3D graphene loaded on the diaphragm is 3mg/cm -2 . CR2016 button cell was assembled in an argon filled glove box with oxygen and moisture levels below 0.1ppm. The electrolyte is LiPF 6 (1mol L -1 ) (solvent is dimethyl carbonate (DMC)/Ethylene Carbonate (EC) (V DMC: V ec=1:1). Electrochemical performance was tested using a Land-CT2001A battery tester with a voltage range between 0.01 and 2.0V.
Fig. 12 shows the results of rate performance tests of the 3D graphene prepared in examples 1, 2, and 3. The multiplying power performance of the N-B doped 3D graphene is 0.2A g -1 、0.5A g -1 、1A g -1 ,2A g -1 And 5Ag -1 At average current densities of 1525mAh g, respectively -1 、1320mAh g -1 、1100mAh g -1 、957mAh g -1 And 670mAh g -1 Is higher than the capacity of N-doped 3D graphene and 3D graphene. The multiplying power performance of the N-doped 3D graphene is 0.2A g -1 、0.5A g -1 、1A g -1 ,2A g -1 And 5Ag -1 At an average current density of 1300mAh g, respectively -1 、925mAh g -1 、630mAh g -1 、470mAh g -1 And 287mAh g -1 . The multiplying power performance of the 3D graphene is 0.2A g -1 、0.5A g -1 、1A g -1 ,2A g -1 And 5Ag -1 At a current density of 1100mAh g, respectively -1 、795mAh g -1 、490mAh g -1 、250mAh g -1 And 66mAh g -1
Fig. 13 shows cycle performance of 3D graphene prepared in examples 1, 2, and 3. From FIG. 13It was found that 3mg cm -2 B-N doped 3D graphene at 1Ag -1 And 970mAh g is still provided after the next 700 cycles -1 While under the same conditions, the N-doped 3D graphene and the undoped 3D graphene can only provide 630mAh g respectively -1 And 416mAh g -1 Is a function of the capacity of the battery.
According to the analysis, the N-B doped 3D graphene has the advantages of high capacity, high rate performance, cycle stability and ultrahigh elasticity.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (10)

1. The 3D graphene is characterized by being of a network structure formed by nanorods;
the diameter of the nano rod is 100-400 nm; a mesoporous is formed on the nano rod;
the network structure has pores with a diameter of 3-6 μm.
2. The 3D graphene according to claim 1, wherein the network structure has pores with a diameter of 3 to 5 μm, and the nanorods have mesopores with a diameter of 1 to 7nm formed thereon;
optionally, the specific surface area of the 3D graphene is 800-1200 m 2 g -1
3. The 3D graphene according to claim 1, wherein the 3D graphene is an N-doped 3D graphene, the network structure has pores with a diameter of 4-6 μm, and the nanorods have mesopores with a diameter of 2-6 nm formed thereon;
optionally, the doping amount of N is 3-5 wt%;
alternatively, the process may be carried out in a single-stage,the specific surface area of the N-doped 3D graphene is 500-800 m 2 g -1
4. The 3D graphene according to claim 1, wherein the 3D graphene is a B-N doped 3D graphene, the network structure has pores with a diameter of 4-6 μm, and the nanorods have mesopores with a diameter of 2-6 nm formed thereon;
optionally, the doping amount of N is 1-2 wt%, and the doping amount of B is 0.3-0.6 wt%;
optionally, the specific surface area of the B-N doped 3D graphene is 450-600 m 2 g -1
5. A method for preparing the 3D graphene according to any one of claims 1 to 4, comprising: graphene is grown on mesoporous silica, and then the mesoporous silica is removed.
6. The method of preparing 3D graphene according to claim 5, wherein growing graphene on mesoporous silica comprises:
step 1, ar and H with flow rates of 280-320 sccm and 40-60 sccm are used respectively 2 Flushing a tubular furnace with mesoporous silica inside for 10-30 min;
step 2, heating the tube furnace to 750-850 ℃ and preserving heat for 30min; continuously introducing a carbon source at a flow rate of 10-30 sccm in the heating and heat preservation processes, and growing graphene by using a vapor deposition technology; then heating the tube furnace to 1050-1150 ℃, preserving heat for 40-80 min, and finally stopping introducing the carbon source.
7. The method of preparing 3D graphene according to claim 5, wherein the 3D graphene is an N-doped 3D graphene, and growing graphene on mesoporous silica comprises:
step 1', adopting Ar to carry a carbon source and a nitrogen source at the flow rate of 80-120 sccm to flush a tubular furnace with mesoporous silica inside for 10-30 min at room temperature;
and 2', heating the tube furnace to 1050-1150 ℃ within 80min, continuously introducing Ar carrying the carbon source and the nitrogen source at the flow rate in the step 1' in the heating process, keeping the temperature for 10-30 min after heating to 1050-1150 ℃, and finally stopping introducing Ar carrying the carbon source and the nitrogen source.
8. The method of preparing 3D graphene according to claim 5, wherein the 3D graphene is a B-N doped 3D graphene, and growing graphene on mesoporous silica comprises:
step 1", flushing a tubular furnace with mesoporous silica inside by Ar at the flow rate of 80-120 sccm with a carbon source, a nitrogen source and a boron source for 10-30 min at room temperature;
and 2', heating the tube furnace to 1050-1150 ℃ within 80min, continuously introducing Ar carrying a carbon source, a nitrogen source and a boron source at the flow rate in the step 1' in the heating process, heating to 1050-1150 ℃ and then preserving heat for 10-30 min, and finally stopping introducing Ar carrying the carbon source, the nitrogen source and the boron source.
9. The method for preparing 3D graphene according to any one of claims 5 to 8, wherein the method for preparing mesoporous silica comprises:
(1) Mixing a surfactant, water and acid, adding a silicon source, and stirring to obtain sol;
alternatively, the acid is HCl, H 2 SO 4 Or H 3 PO 4 At least one of (a) and (b);
(2) Transferring the sol into an autoclave, heating the autoclave to 120-150 ℃ for hydrothermal reaction for 24-48 hours;
(3) And drying and calcining to obtain the mesoporous silica.
10. The method for preparing 3D graphene according to claim 6, wherein the carbon source is CH 4 、C 2 H 6 Or C 3 H 8 At least one of them.
CN202310509706.XA 2023-05-06 2023-05-06 3D graphene and preparation method thereof Pending CN116395678A (en)

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