Preparation method and application of defect-induced synthetic porous carbon nanocomposite

Abstract

The application discloses a preparation method of defect-induced synthesis of porous carbon nanocomposites and application thereof in supercapacitors. The method uses DHPC as a carbon base to anchor Mn3O4. A large number of intrinsic defects on the surface of the DHPC optimize the local electron density distribution and surface performance, accelerate ion kinetics, provide abundant nucleation sites, and enhance the binding activity with Mn3O4. The microwave-assisted synthesis technology is used to realize the uniform dispersion of Mn3O4 nanoparticles on the DHPC, forming a three-dimensional porous network structure. The structure not only improves the conductivity of Mn3O4, but also promotes the rapid diffusion of electrolyte ions and electron transmission, simultaneously relieves the stress damage in the charging and discharging process, and significantly improves the electrochemical performance and cycle stability of the material. Compared with the prior art, the preparation method has the advantages of simple operation, low cost, environmental friendliness and the like.

Description

Technical Field

[0001] This invention belongs to the field of electrode material technology, specifically relating to a method for preparing and applying defect-induced porous carbon nanocomposite materials. Background Technology

[0002] In the field of energy storage, supercapacitors have attracted much attention due to their high power density and long lifespan. Electrode materials are a key factor determining the performance of supercapacitors. Traditional electrode materials, such as activated carbon and metal oxides, while performing well in some aspects, still have limitations. For example, activated carbon has a high specific surface area but a low specific capacitance; metal oxides such as MnO2 have high specific capacitance but poor conductivity and are prone to volume expansion during charge and discharge, leading to structural damage and performance degradation.

[0003] To address these issues, researchers began exploring strategies for combining metal oxides with carbon materials. For example: (1) Chemical vapor deposition, which can precisely control the size and shape of nanoparticles on various substrates and is suitable for the preparation of large-area uniform coatings, but usually requires high temperature and high vacuum environments, resulting in high energy consumption and certain limitations on the selection of precursors, as well as high equipment and operating costs; (2) Solution impregnation, which is simple to operate and low in cost, and the distribution and size of nanoparticles can be adjusted by changing the solution concentration and pH value, but it may be difficult to achieve a highly uniform distribution of nanoparticles, and the reaction conditions (such as temperature and time) have a significant impact on the performance of the final product; (3) Solvothermal method, which is carried out in a closed container, avoiding interference from oxygen and moisture, and can prepare nanostructures of various forms, but the reaction time is long, and the selection and recovery of solvents may bring environmental and cost problems; (4) Electrochemical deposition, which can be carried out at room temperature and has low energy consumption, and the deposition of nanoparticles can be precisely controlled by changing electrochemical parameters, but it may require complex electrochemical equipment and the deposition rate may be slow.

[0004] In summary, although studies have reported on the preparation of metal oxide and carbon composite materials, these methods are often complex, time-consuming, and challenging in terms of uniform dispersion of nanoparticles and prevention of agglomeration.

[0005] Mn3O4, as a metal oxide with high specific capacitance, has attracted widespread attention. However, its poor conductivity and small specific surface area limit its application in supercapacitors. To improve these properties, researchers have attempted to enhance its electrochemical performance by constructing composite materials of Mn3O4 and carbon materials. For example, patent CN103647068A uses a liquid-phase reaction combined with high-temperature treatment to prepare Mn3O4 / multi-walled carbon nanotube composites, but the uniformity of the material particles is difficult to control during the reaction, affecting the final material's performance. Furthermore, patent CN111126459A describes a method for preparing Mn3O4 / C composites based on hydrothermal synthesis. Although this method can control the morphology and size of Mn3O4 to some extent, its reaction conditions are harsh, and it is difficult to precisely control the distribution of Mn3O4 on the carbon substrate, potentially leading to inconsistent composite material performance. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing a method for preparing and applying defect-induced porous carbon nanocomposites.

[0007] This invention is achieved through the following technical solution:

[0008] A method for preparing defect-induced porous carbon nanocomposites includes the following steps:

[0009] a. Mix and grind o-phenanthroline and potassium hydroxide evenly, perform carbonization treatment, cool, wash and dry to obtain nitrogen-doped porous carbon material (NHPC);

[0010] b. NHPC is subjected to high-temperature treatment to remove heteroatoms introduced into the material and is then naturally cooled to room temperature to obtain carbon material rich in intrinsic defects (DHPC);

[0011] c. Dissolve DHPC in ethylene glycol solution to prepare a DHPC ethylene glycol suspension with a concentration of 0.5 mg / mL;

[0012] d. Slowly add a 0.5M manganese acetate / ethylene glycol solution to the suspension;

[0013] e. Gradually add sodium hydroxide / ethylene glycol solution to the mixture obtained in step d, and adjust the pH to around 8;

[0014] f. Transfer the mixture to a microwave oven reactor, set the microwave power to 700W, and the reaction time to 90s;

[0015] g. The mixture after microwave reaction was filtered, washed, and vacuum dried to obtain the Mn3O4 / DHPC composite material.

[0016] Furthermore, in step a, the mass ratio of o-phenanthroline to potassium hydroxide is 1:4.

[0017] Furthermore, the carbonization treatment in step a specifically involves: in an inert atmosphere at 5°C for 1 minute... -1 Heat to 800℃ at a rising rate and hold for 2 hours.

[0018] Furthermore, the carbonization treatment in step b specifically involves: operating under N2 protection at 5°C for 5 minutes. -1 The temperature was increased to 1150℃ at a certain rate and held for 2 hours.

[0019] The present invention also provides a defect-induced synthesis of porous carbon nanocomposite material, which is obtained by the preparation method described above.

[0020] The present invention also provides the application of the defect-induced porous carbon nanocomposite material, using it as an electrode material for electrochemical energy storage devices.

[0021] Compared with the prior art, the beneficial effects of this invention are as follows:

[0022] 1. Improved Dispersion Uniformity: In existing technologies, the dispersion of metal nanoparticles on porous carbon substrates is often not uniform enough, resulting in limited performance of composite materials. This invention achieves uniform distribution of metal nanoparticles on nanocage-like porous carbon substrates through a defect-induced mechanism. By utilizing the intrinsic defects on the surface of the nanocage-like porous carbon as nucleation sites, the uniform dispersion of metal nanoparticles is effectively promoted, thereby improving the electrochemical activity and stability of the composite material.

[0023] 2. Enhanced Anchoring Activity: In existing technologies, the bonding force between metal oxide nanoparticles and carbon materials is relatively weak, making them prone to detachment during electrochemical reactions. This invention enhances the interaction between nanoparticles and porous carbon substrates through a defect-inducing strategy, thereby improving anchoring activity and enhancing the structural stability and cycle life of the composite material.

[0024] 3. Simplified Synthesis Process: Traditional synthesis methods are typically cumbersome, time-consuming, and difficult to precisely control the size and distribution of nanoparticles. This invention employs a microwave-assisted synthesis method, simplifying the preparation process, shortening the reaction time, and achieving precise control over the size and distribution of nanoparticles through the uniformity of microwave heating. This method is not only easy to operate but also enables the production of high-quality composite materials in a shorter time, which helps reduce production costs and improve production efficiency.

[0025] 4. Enhanced Electrochemical Performance: The electrochemical performance of composite materials in existing technologies is limited by the dispersion of metal nanoparticles and their bonding strength with the carbon substrate. This invention significantly improves the specific capacitance, energy density, and power density of the composite material through defect-induced and uniformly dispersed metal nanoparticles, as well as an optimized three-dimensional porous network structure, providing possibilities for high-performance energy storage devices. Due to the tight bonding between the metal nanoparticles and the porous carbon substrate, the composite material prepared by this invention exhibits superior electrochemical performance, including higher specific capacitance, better cycle stability, and better charge-discharge performance. This is particularly important for energy storage devices such as supercapacitors, as they require electrode materials with high energy storage capacity and long service life.

[0026] 5. Optimization of Structure and Performance: The defect-inducing strategy of this invention enhances the interaction between metal nanoparticles and the porous carbon substrate, thereby improving the structural stability of the composite material. This means that during the electrochemical reaction, the metal nanoparticles are less likely to detach, helping to maintain the structural integrity of the electrode and extend the service life of the device. This invention not only focuses on the synthesis of composite materials but also achieves optimized matching between material structure and electrochemical performance through in-depth research on the defect-inducing mechanism and the interaction between nanoparticles and porous carbon, providing new theoretical guidance and practical methods for the design and preparation of high-performance composite materials.

[0027] In summary, the technical solution of this invention effectively improves upon existing technologies by addressing issues such as uneven dispersion, weak bonding, complex synthesis processes, and limited electrochemical performance, providing a novel strategy for preparing high-performance metal oxide / porous carbon composite materials. This invention achieves rapid one-step synthesis, successfully anchoring Mn3O4 nanoparticles uniformly onto defect-rich porous carbon materials, thereby obtaining Mn3O4 / C composite materials with excellent electrochemical performance. Compared to existing technologies, the method of this invention offers advantages such as short reaction time, simple operation, mild conditions, easy control of nucleation and suppression of nucleus growth, uniform oxide dispersion, and high production efficiency. Furthermore, the composite material of this invention exhibits higher specific capacitance and good cycle stability, providing a new solution for electrode materials in high-performance supercapacitors. Attached Figure Description

[0028] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0029] Figure 1Scanning electron microscope image of Mn3O4 / DHPC;

[0030] Figure 2 Transmission electron microscopy (TEM) image of Mn3O4 / DHPC;

[0031] Figure 3 Selected area electron diffraction pattern of Mn3O4 / DHPC;

[0032] Figure 4 The X-ray diffraction pattern of Mn3O4 / DHPC;

[0033] Figure 5 The X-ray diffraction pattern of Mn3O4 / NHPC is shown.

[0034] Figure 6 The image shows a scanning electron microscope (SEM) image of Mn3O4 / NHPC.

[0035] Figure 7 Mn3O4 / DHPC in 10Ag -1 The following is a graph showing the cyclic stability test results. Detailed Implementation

[0036] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] This invention discloses an embodiment of a method for preparing defect-induced porous carbon nanocomposites, the specific operation steps of which are as follows:

[0038] a. Mix o-phenanthroline and potassium hydroxide at a mass ratio of 1:4 and grind them evenly. Then place the mixture in a tube furnace and heat it at 5°C for 1 minute under an inert atmosphere. -1 The material was heated to 800°C at a heating rate and held for 2 hours. After the tube furnace cooled to room temperature, the material was removed, washed repeatedly with dilute hydrochloric acid solution and deionized water, and then dried overnight at 60°C to obtain nitrogen-doped hierarchical porous carbon (NHPC).

[0039] b. Place NHPC inside a corundum boat and incubate at 5°C for 5 min under N2 protection. -1 The temperature was raised to 1150℃ at a certain heating rate, held at that temperature for 2 hours, and then naturally cooled to room temperature. The resulting material is a carbon material rich in intrinsic defects (DHPC).

[0040] c. Disperse 20 mg DHPC in 40 mL of ethylene glycol (EG) solution under magnetic stirring to form a uniform suspension.

[0041] d. Slowly add 8 mL of 0.5 M manganese acetate / ethylene glycol (Mn(CH3COO)2 / EG) solution to the suspension and stir continuously for 30 minutes to ensure complete reaction.

[0042] e. Gradually add 2M sodium hydroxide / ethylene glycol (NaOH / EG) solution to the mixture and adjust the pH to around 8.

[0043] f. Transfer the mixture to a microwave oven reactor, set the microwave power to 700W, and the reaction time to 90s.

[0044] g. After the reaction is complete, the mixture is filtered, washed with deionized water and ethanol, and finally vacuum dried in an oven at 80°C to obtain the Mn3O4 / DHPC composite material.

[0045] Figure 1 The image shows a scanning electron microscope (SEM) image of Mn3O4 / DHPC. As can be seen from the image, Mn3O4 nanoparticles are uniformly and orderly distributed on the surface of carbon nanosheets. This composite material of metal oxide and porous carbon is conducive to the full wetting of electrolyte and the adsorption and embedding of electrochemically active ions. Furthermore, the structure has abundant electronic conduction pathways, thereby improving the utilization rate of electrode active materials.

[0046] Figure 2 This is a transmission electron microscope (TEM) image of Mn3O4 / DHPC, which allows for further observation of the material morphology and surface nanoparticles. As shown in the figure, Mn3O4 nanoparticles are uniformly and densely distributed on the surface of carbon nanosheets, and the image clearly shows the lattice fringes of the metal oxide in Mn3O4 / DHPC. The spacing of the fringes is 0.25 nm, which belongs to the (211) crystal plane of Mn3O4 (JCPDS NO. 24-0734), verifying that the nanoparticles on the DHPC surface are indeed Mn3O4. Meanwhile... Figure 3 Selected area electron diffraction (SAED) patterns of the medium and nanoparticles confirmed the existence of the (321), (211), (112), and (101) crystal planes of Mn3O4. These results demonstrate the successful preparation of the Mn3O4 / DHPC composite material.

[0047] Figure 4 and Figure 5X-ray diffraction (XRD) spectra of Mn3O4 / DHPC and Mn3O4 / NHPC were shown. The crystal structures of the two materials were characterized using XRD. The results showed that the diffraction peaks at 2θ = 18.2°, 29.0°, 31.1°, 32.5°, 36.2°, 38.2°, 44.6°, 50.8°, 60.0°, and 64.5° correspond to the (101), (112), (200), (103), (211), (004), (220), (105), (321), and (116) crystal planes of the Mn3O4 structure (ferromanganese, JCPDS24-0734), respectively. The (211) crystal plane is a characteristic diffraction plane of Mn3O4. Figure 2 The high-magnification transmission electron microscopy (TEM) images show that the lattice fringes correspond to the same crystal planes. Furthermore, the sharper the peak shape and the greater the peak intensity of the XRD diffraction peaks, the higher the crystallinity of the material and the more complete its long-range ordered structure.

[0048] Figure 6 The image shows a scanning electron microscope (SEM) image of Mn3O4 / NHPC deposited on NHPC as a carbon substrate. The image shows that the Mn3O4 nanoparticles on the surface of the composite material exhibit some agglomeration and the content of Mn3O4 is also lower.

[0049] Figure 7 Mn3O4 / DHPC in 10Ag -1 Cyclic stability tests conducted at a constant current density show that the electrode maintains high coulombic efficiency and capacity retention after 5000 cycles. This is mainly due to the carbon nanosheets mitigating stress damage to Mn3O4 during redox processes. Furthermore, the carbon composite also improves the conductivity of Mn3O4. The three-dimensional porous network structure formed by the combination of nanoparticles and porous carbon materials facilitates ion diffusion and electron transport in the electrolyte, thereby enhancing the electrochemical performance of the material.

[0050] To verify the impact of defects on electrochemical performance, a Mn3O4 / NHPC composite material was prepared using Comparative Example 1 for comparison.

[0051] Comparative Example 1

[0052] This comparative example follows the preparation method of the embodiment, omitting step b, and replacing DHPC with NHPC in step c. The remaining steps are the same, and the final result is a Mn3O4 / NHPC composite material.

[0053] To verify the effect of Mn3O4 content, Mn3O4 / DHPC samples with different Mn3O4 loadings were prepared using Comparative Example 2 and Comparative Example 3 by changing the concentration of Mn(CH3COO)2 / EG solution.

[0054] Comparative Example 2

[0055] This comparative example follows the preparation method of the embodiment, except that in step d, a 0.4M Mn(CH3COO)2 / EG solution is used, and the resulting sample is named Mn3O4 / DHPC-0.4M.

[0056] Comparative Example 3

[0057] This comparative example follows the preparation method of the embodiment, except that a 0.6M Mn(CH3COO)2 / EG solution is used in step d, and the resulting sample is named Mn3O4 / DHPC-0.6M.

[0058] To verify the effect of microwave reaction time, Comparative Examples 4 and 5 were used to prepare Mn3O4 / DHPC samples by changing the microwave treatment time.

[0059] Comparative Example 4

[0060] This comparative example follows the preparation method of the embodiment, except that the microwave reaction time in step f is set to 30s, and the resulting sample is named Mn3O4 / DHPC-30s.

[0061] Comparative Example 5

[0062] This comparative example follows the preparation method of the embodiment, except that the microwave reaction time in step f is set to 60s, and the resulting sample is named Mn3O4 / DHPC-60s.

[0063] The capacitance performance results of the Mn3O4 / DHPC and Mn3O4 samples prepared in the embodiments of the present invention, and the samples obtained from Comparative Examples 1-5 are shown in Table 1. Among them, the specific capacitance of Mn3O4 / DHPC is significantly higher than that of other samples.

[0064] Table 1 Performance data of application examples

[0065]

[0066]

[0067] This invention provides a method for synthesizing porous carbon nanocomposites through intrinsic defect induction and their application in supercapacitors. The method utilizes DHPC as a carbon substrate to anchor Mn3O4. The surface of DHPC possesses numerous intrinsic defects, which optimize the local electron density distribution and surface properties, accelerate ion dynamics, provide abundant nucleation sites, and enhance the binding activity with Mn3O4. Through microwave-assisted synthesis, this method achieves uniform dispersion of Mn3O4 nanoparticles on DHPC, forming a three-dimensional porous network structure. This structure not only improves the conductivity of Mn3O4 but also promotes rapid ion diffusion and electron transport in the electrolyte, while mitigating stress damage during charge and discharge, significantly enhancing the electrochemical performance and cycle stability of the material. Compared to existing technologies, the preparation method provided by this invention has advantages such as simple operation, low cost, and environmental friendliness. Furthermore, the Mn3O4 / DHPC composite material prepared by this method exhibits higher specific capacity at the same current density, making it suitable as an electrode material for high-performance electrochemical energy storage devices. This invention provides new ideas and directions for the design and preparation of next-generation high-performance composite electrode materials.

Claims

1. A method for preparing defect-induced porous carbon nanocomposites, characterized in that, Includes the following steps: a. Mix o-phenanthroline and potassium hydroxide at a mass ratio of 1:4 and grind them evenly. Then, perform the mixture under an inert atmosphere at 5... o Cmin -1 Heating rate to 800 o After carbonization at C for 2 hours, the material was cooled, washed, and dried to obtain nitrogen-doped porous carbon material (NHPC). b. Perform NHPC under N2 protection at 5 o C min -1 The heating rate is increased to 1150. o The material is subjected to high-temperature treatment at C for 2 hours to remove heteroatoms that introduce intrinsic defects, and then naturally cooled to room temperature to obtain carbon material rich in intrinsic defects (DHPC). c. Dissolve DHPC in ethylene glycol solution to prepare a DHPC ethylene glycol suspension with a concentration of 0.5 mg / mL; d. Slowly add a 0.5 M manganese acetate / ethylene glycol solution to the suspension; e. Gradually add sodium hydroxide / ethylene glycol solution to the mixture obtained in step d, and adjust the pH to around 8; f. Transfer the mixture to a microwave oven reactor, set the microwave power to 700 W, and the reaction time to 90 s; g. The mixture after microwave reaction was filtered, washed, and vacuum dried to obtain Mn3O4 / DHPC composite material, in which Mn3O4 nanoparticles were uniformly and orderly distributed on the surface of carbon nanosheets.

2. A defect-induced synthesis of porous carbon nanocomposite materials, characterized in that, It is obtained by the preparation method described in claim 1.

3. The application of the defect-induced synthesized porous carbon nanocomposite material according to claim 2, characterized in that, The defect was used to induce the synthesis of porous carbon nanocomposites, which were then used as electrode materials for electrochemical energy storage devices.

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