Preparation method of high-edge nitrogen-doped high-density carbon for zinc ion capacitor

Abstract

The invention discloses a preparation method of high-edge nitrogen-doped high-density carbon and an application of the high-edge nitrogen-doped high-density carbon as a positive electrode of a zinc ion capacitor, and the method comprises the following steps: S1, dissolving zinc nitrate and urea in deionized water, then transferring the solution to a hydrothermal reaction kettle, and carrying out a high-temperature reaction to obtain a basic zinc carbonate template; s2, basic zinc carbonate is heated to the growth temperature in a tubular furnace under the inert atmosphere, then the nitrogen-containing precursor is injected into a reaction system for carbon deposition, and a ZnO-nitrogen-doped carbon sample is obtained after deposition is finished; and S3, washing the sample obtained in the step S2 with acid to remove ZnO, then washing the sample with a solvent until the sample is neutral, and drying the sample to obtain the high-density carbon. The obtained carbon material has the characteristics of high conductivity (150 S / m), high specific surface area (1600 m < 2 > / g), high density (1.3 g / cm < 3 >), high edge nitrogen and micropore-mesopore coexistence. As the positive electrode material of the zinc ion capacitor, the material shows high specific capacitance, rate capability and cycling stability.

Description

Technical Field

[0001] This invention relates to the field of edge nitrogen-doped high-density carbon preparation technology, specifically a method for preparing high-edge nitrogen-doped high-density carbon for zinc-ion capacitors. Background Technology

[0002] Zinc-ion capacitors combine the high energy density of zinc-ion batteries with the high power density and long-cycle stability of supercapacitors, making them a highly competitive power source alternative. Carbon materials are the primary cathode materials for zinc-ion capacitors, and their pore structure and surface electronic structure play a crucial role in their performance. Ideal carbon materials must possess not only a large specific surface area but also high density and abundant active sites, simultaneously satisfying the mass and volumetric performance requirements of zinc-ion capacitors, thus laying the foundation for their application in portable and flexible electronic devices. Based on volumetric capacitance (C... v = ρ × C g As can be seen, in high-quality specific capacity (C) g Under certain conditions, increasing electrode density (ρ) is an effective way to achieve high volumetric capacity. However, high density often leads to a decrease in specific surface area and reduced pore accessibility, resulting in a decline in volumetric capacity and rate performance.

[0003] Heteroatom doping can modulate the surface electronic structure of carbon materials and increase electrochemical active sites. Nitrogen (N) doping is an effective strategy for improving zinc ion storage in carbon materials. Among different N species, edge N (including pyridine-N and pyrrole-N) have strong cation affinity and play an important role in zinc ion capacitors. However, the formation of pyridine-N and pyrrole-N is highly dependent on the presence of defects and edge sites in the carbon matrix.

[0004] Therefore, constructing carbon materials with abundant edge structures and high density is a necessary condition for achieving high-quality and volumetric performance zinc-ion capacitors. Summary of the Invention

[0005] This invention provides a high-density carbon material with high edge nitrogen doping for zinc-ion capacitors, which can effectively solve the problem of preparing high-density carbon materials mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-density carbon material with high edge nitrogen doping for zinc-ion capacitors, the preparation method of which includes the following steps: S1. Dissolve Zn(NO3)2·6H2O and urea in deionized water, then transfer the mixed solution to a hydrothermal reactor. After high-temperature hydrothermal reaction, filter the precipitate and vacuum dry it at 80 °C for 12 h to obtain basic zinc carbonate (Zn5(OH)6(CO3)2) template. S2. In an inert atmosphere, basic zinc carbonate (Zn5(OH)6(CO3)2) is heated to the growth temperature in a tube furnace at a rate of 5~10 °C / min. Subsequently, a nitrogen-containing precursor is injected into the above reaction system using an injection pump for carbon deposition growth. After deposition, the system is allowed to cool naturally to room temperature to obtain a gray ZnO@nitrogen-doped carbon sample. S3. The ZnO@nitrogen-doped carbon sample obtained in step S2 is soaked in acid and filtered to remove the ZnO template. Then it is washed with solvent until neutral and then vacuum dried to obtain high-edge nitrogen-doped high-density carbon material.

[0007] According to the above technical solution, the inert gas in S2 is argon, nitrogen, or a mixture of the two, the growth temperature is 700~900℃, the nitrogen-containing precursor is one or more of acetonitrile, triethylamine, tetramethylethylenediamine, etc., and the carbon growth reaction time is 5~20 min.

[0008] According to the above technical solution, the dilute acid in S3 is dilute hydrochloric acid or dilute sulfuric acid or a mixture of the two, which can dissolve the etching solution of ZnO; the solvent used is one or more of deionized water, ethanol, methanol, and acetone.

[0009] Compared with existing materials, the beneficial effects of the present invention are as follows: (1) The N-doped high-density carbon material obtained in this invention has the advantages of high conductivity (150 S / m) and high specific surface area (1600 m²) compared with other carbon materials. 2 / g), high density (1.3 g / cm³) 3 The high specific surface area and abundant edge N sites, along with the micropore-mesopore coexistence feature, are structural advantages crucial for portable and miniaturized energy storage devices. High specific surface area and edge nitrogen content ensure high energy density, which contributes to flexible and compact energy storage, while high conductivity and the micropore-mesopore coexistence feature help improve power density. (2) The N-doped high-density carbon material obtained in this invention exhibits a high volumetric / mass specific capacitance as a positive electrode material for zinc-ion capacitors, which is 244 mAh / cm³ at 1 A / g. 3 With a capacity of 188 mAh / g, even at an ultra-high current density of 80 A / g, the specific capacity remains at 130 mAh / cm³. 3 With a capacity of 100 mAh / g, its highest energy density and power density reach 205 Wh / L (158 Wh / kg) and 117.3 kW / L (90.5 kW / kg), respectively. At 10A g... -1 After 50,000 cycles at a current density, the capacitance loss is only 6.9%, which is at the leading level of zinc ion capacitors. Attached Figure Description

[0010] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0011] In the attached diagram: Figure 1 Scanning electron microscope image of a basic zinc carbonate (Zn5(OH)6(CO3)2) template; Figure 2 Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of high-density carbon materials with high edge nitrogen doping; Figure 3 X-ray photoelectron spectra of high-density carbon materials with high edge nitrogen doping; Figure 4 : Pore structure diagram of high-density carbon material with high edge nitrogen doping; Figure 5 Performance of high-density carbon with high edge nitrogen doping in zinc ion capacitors in 2 mol / L ZnSO4 electrolyte: (a) mass / volume capacitance at different current densities, (b) Ragone plot, (c) cycling stability at 10 A / g current density. Figure 6 Application demonstration of zinc-ion capacitors assembled with high-density carbon with high edge nitrogen doping as the positive electrode. Detailed Implementation

[0012] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Example 1

[0013] Step (1): Dissolve 2 g Zn(NO3)2·6H2O and 3 g urea in 60 mL of deionized water, then transfer the mixed solution to a hydrothermal reactor and hydrothermally react at 120°C for 12 h. Filter the precipitate and vacuum dry it at 80°C for 12 h to obtain the basic zinc carbonate (Zn5(OH)6(CO3)2) template. Step (2): Take 3.0 g of basic zinc carbonate (Zn5(OH)6(CO3)2) and place it in a vertical tube furnace with a sand core. Introduce N2 gas at a flow rate of 100 sccm for 30 min to fully remove the air in the tube. Heat the furnace to 700 °C at a rate of 10 °C / min. Step (3): Use a syringe pump to dispense 50 μL / min -1The N-containing precursor N,N,N',N'-tetramethylethylenediamine was injected into the above reaction system at a rate of 5 min for carbon deposition growth. After deposition, the system was kept at 700 °C for 2 h. After the system cooled naturally to room temperature, the ZnO@nitrogen-doped carbon sample was taken out. Step (4): The ZnO@nitrogen-doped carbon sample described in step (3) was soaked and washed three times with 3 mol / L dilute HCl to remove the ZnO template, then washed with ethanol until neutral, and finally vacuum dried at 80 °C for 12 h to obtain a high-density carbon material with high edge N doping. Example 2

[0014] Step (1): Dissolve 2 g Zn(NO3)2·6H2O and 3 g urea in 60 mL of deionized water, then transfer the mixed solution to a hydrothermal reactor and hydrothermally react at 120°C for 12 h. Filter the precipitate and vacuum dry it at 80°C for 12 h to obtain the basic zinc carbonate (Zn5(OH)6(CO3)2) template. Step (2): Take 3.0 g of basic zinc carbonate (Zn5(OH)6(CO3)2) and place it in a vertical tube furnace with a sand core. Introduce N2 gas at a flow rate of 100 sccm for 30 min to fully remove the air in the tube. Heat the furnace to 700 °C at a rate of 10 °C / min. Step (3): Use a syringe pump to dispense 50 μL / min -1 The nitrogen-containing precursor triethylamine was injected into the above reaction system at a rate of 5 min for carbon deposition growth. After deposition, the system was kept at 700 °C for 2 h. After the system cooled naturally to room temperature, the ZnO@nitrogen-doped carbon sample was taken out. Step (4): The ZnO@nitrogen-doped carbon sample described in step (3) was soaked and washed three times with 3 mol / L dilute HCl to remove the ZnO template. Then it was washed with ethanol until neutral and finally vacuum dried at 80 °C for 12 h to obtain a high-density carbon material with high edge N doping. Example 3

[0015] Step (1): Dissolve 2 g Zn(NO3)2·6H2O and 3 g urea in 60 mL of deionized water, then transfer the mixed solution to a hydrothermal reactor and hydrothermally react at 120°C for 12 h. Filter the precipitate and vacuum dry it at 80°C for 12 h to obtain the basic zinc carbonate (Zn5(OH)6(CO3)2) template. Step (2): Take 4.0 g of basic zinc carbonate (Zn5(OH)6(CO3)2) and place it in a vertical tube furnace with a sand core. Introduce N2 gas at a flow rate of 100 sccm for 30 min to fully remove the air in the tube. Heat the furnace to 700 °C at a rate of 10 °C / min. Step (3): Use a syringe pump to dispense 50 μL / min -1 The nitrogen-containing precursor acetonitrile was injected into the above reaction system at a rate of 5 min for carbon deposition growth. After deposition, the system was kept at 700 °C for 2 h. After the system cooled naturally to room temperature, the ZnO@nitrogen-doped carbon sample was taken out. Step (4): The ZnO@nitrogen-doped carbon sample described in step (3) was soaked and washed three times with 3 mol / L dilute HCl to remove the ZnO template. Then it was washed with ethanol until neutral and finally vacuum dried at 80 °C for 12 h to obtain a high-density carbon material with high edge N doping.

[0016] The high-density carbon material with high edge N-doping obtained in Example 1 was used as the positive electrode of a zinc-ion capacitor, commercial zinc foil was used as the negative electrode, and a 2 mol / L ZnSO4 aqueous solution was used as the electrolyte. The performance of the zinc-ion capacitor was tested. The test results are as follows: Volumetric capacity at a current density of 1 A / g ( C vol ) is 244 mAh / cm 3 (Specific capacity is 188 mAh / g), and even at an ultra-high current density of 80 A / g, the specific capacity remains at 130 mAh / cm³. 3 (100 mAh / g), exhibiting high rate performance. In terms of volumetric power density ( P vol The corresponding volumetric energy density at a power density of 1.46 kW / L (1.13 kW / kg) is ( E vol With a capacity as high as 205 Wh / L (158 Wh / kg), it exhibits excellent charge storage capability. After 50,000 cycles at a current density of 10 A / g, the capacity loss is only 6.9%, demonstrating excellent cycle stability (see [link to relevant documentation]). Figure 5 ).

[0017] The high-density N-doped carbon obtained in Example 2 was used as the positive electrode of a zinc-ion capacitor, commercial zinc foil was used as the negative electrode, and a 2 mol / L ZnSO4 aqueous solution was used as the electrolyte. The performance of the zinc-ion capacitor was tested. The test results are as follows: Volumetric capacity at a current density of 1 A / g ( C volThe value is 209 mAh / cm³. 3 (Specific capacity is 188 mAh / g), and even at an ultra-high current density of 80 A / g, the specific capacity remains at 86 mAh / cm³. 3 (66 mAh / g), exhibiting high rate performance. In terms of volumetric power density ( P vol The corresponding volumetric energy density at a power density of 1.45 kW / L (1.12 kW / kg) is ( E vol With a capacity of up to 172 Wh / L (132 Wh / kg), it exhibits excellent charge storage capability. After 50,000 cycles at a current density of 10 A / g, the capacity loss is only 8.7%, demonstrating excellent cycle stability.

[0018] The high-density N-doped carbon obtained in Example 3 was used as the positive electrode of a zinc-ion capacitor, commercial zinc foil was used as the negative electrode, and a 2 mol / L ZnSO4 aqueous solution was used as the electrolyte. The performance of the zinc-ion capacitor was tested. The test results are as follows: Volumetric capacity at a current density of 1 A / g ( C vol ) is 159 mAh / cm 3 (Specific capacity is 122 mAh / g), and even at an ultra-high current density of 80 A / g, the specific capacity remains at 70 mAh / cm³. 3 (54 mAh / g), exhibiting high rate performance. In terms of volumetric power density ( P vol The corresponding volumetric energy density at a power density of 1.44 kW / L (1.11 kW / kg) is ( E vol With a capacity of up to 134 Wh / L (103 Wh / kg), it exhibits excellent charge storage capability. After 50,000 cycles at a current density of 10 A / g, the capacity loss is only 9.8%, demonstrating excellent cycle stability.

[0019] Descriptions not covered in the specific embodiments of the present invention are known in the art and can be implemented with reference to known techniques.

[0020] This invention has been repeatedly tested and verified, and has achieved satisfactory trial results.

[0021] The embodiments of the present invention are not limited to the above-described embodiments. All changes made without departing from the spirit of the present invention are within the protection scope of the present invention.

Claims

1. A method for preparing high-edge nitrogen-doped high-density carbon for zinc-ion capacitors, characterized by, The method comprises the following steps: S1, dissolving Zn(NO3)2·6H2O and urea in deionized water, then transferring the mixed solution to a hydrothermal reactor, after high-temperature hydrothermal reaction, filtering the precipitate and vacuum drying at 80 ℃ for 12 h to obtain a basic zinc carbonate (Zn5(OH)6(CO3)2) template; S2, in an inert atmosphere, heating the basic zinc carbonate (Zn5(OH)6(CO3)2) in a tube furnace to a growth temperature at a rate of 5-10 ℃ / min; then, injecting a nitrogen-containing precursor into the above reaction system with a syringe pump for carbon deposition growth, after deposition, waiting for the system to naturally cool to room temperature to obtain a gray ZnO@nitrogen-doped carbon sample; S3, soaking the ZnO@nitrogen-doped carbon sample obtained in step S2 with acid, filtering to remove the ZnO template, then washing with a solvent to neutral, and then vacuum drying to obtain a high-edge nitrogen-doped high-density carbon material.

2. The method of claim 1, wherein the high-edge nitrogen-doped high-density carbon for a zinc ion capacitor is prepared by the steps of: preparing a mixture of a carbon source and a nitrogen source; and performing a high-pressure carbonization process on the mixture to prepare the high-edge nitrogen-doped high-density carbon. The inert gas in S2 is argon, nitrogen or a mixture of the two, the growth temperature is 700-900 ℃, the N-containing precursor is one or more of acetonitrile, triethylamine, tetramethyl ethylenediamine, etc., and the carbon growth time is 5-20 min.

3. The method for preparing high-density carbon with high edge nitrogen doping for zinc-ion capacitors according to claim 1, characterized in that, The dilute acid in S3 is dilute hydrochloric acid or dilute sulfuric acid or a mixture of the two, which can dissolve ZnO etching liquid; the solvent used is one or more of deionized water, ethanol, methanol, acetone.

4. The use of the high-edge nitrogen-doped high-density carbon obtained by the preparation method of claim 1 as a zinc ion capacitor electrode material.

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