Preparation method of two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterial and mixed type supercapacitor electrode thereof

Abstract

A method for preparing two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials and their hybrid supercapacitor electrodes is disclosed. Using two-dimensional Ti3C2 nanomaterials as the matrix, melamine phosphate or piperazine phosphate is used as the nitrogen and phosphorus source. A solvothermal method is employed to achieve in-situ doping modification of two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered materials, which are then applied to hybrid supercapacitors. Compared to other reported MXene doping modification methods, nitrogen-phosphorus co-doping can introduce abundant atomic defects and surface active sites, which is beneficial for improving the conductivity of Ti3C2, increasing the active area and ion diffusion space of the material, reducing the charge-mass transfer resistance between the electrode material and the electrolyte, enhancing the ion diffusion rate, and slowing down the volume change of the material during cycling, thereby enhancing its structural and cycling stability. Furthermore, the substitution of functional groups such as -F and -Cl on the Ti3C2 surface by nitrogen and phosphorus elements under high temperature and high pressure reaction conditions enhances the pseudocapacitive activity of Ti3C2, endowing it with stronger charge storage capacity. The successful development of two-dimensional nitrogen-phosphorus co-doped Ti3C2 composite electrode materials will likely drive the application of hybrid supercapacitors in the field of fast charging, providing more efficient, reliable and sustainable energy storage solutions for electric vehicles and consumer electronics.

Description

Technical Field

[0001] This invention belongs to the field of nanofunctional materials and electrochemical energy storage devices, and specifically relates to a two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterial, a hybrid supercapacitor electrode and its preparation method. Background Technology

[0002] With the continuous advancement of technology and the widespread adoption of electric vehicles and consumer electronics, the demand for energy storage technology is rapidly increasing. Among these, fast charging has become a pressing concern for consumers and electric vehicle users. To address this challenge, battery technology needs high power density to achieve shorter charging times and higher power output. However, the battery field has long faced a perplexing problem: high power density and high energy density appear to be mutually restrictive performance indicators. Traditional lithium-ion batteries hold a significant market position due to their ability to provide high energy density through lithium-ion intercalation. However, these batteries have significant limitations in power density and cycle life, particularly in scenarios requiring fast charging and high power output. On the other hand, supercapacitors, due to their rapid ion intercalation and deintercalation at their surface, can achieve excellent power density and long cycle life, but their energy density is far lower than that of traditional lithium-ion batteries, limiting their widespread application in certain sectors.

[0003] Faced with this contradiction, researchers have begun to seek a novel energy storage device that integrates the advantages of traditional lithium-ion batteries and supercapacitors to achieve high energy density, high power density, and long cycle life simultaneously. Achieving this goal will not only meet the demands of fast charging but also propel battery technology towards greater efficiency, reliability, and sustainability, laying a solid foundation for the future development of electric transportation and portable electronic devices. Therefore, developing novel energy storage devices that combine the advantages of batteries and supercapacitors has become a hot topic in electrochemical energy storage technology research, attracting widespread attention from scientists and engineers worldwide. Hybrid supercapacitors (HICs), as an innovative electrochemical energy storage system, cleverly combine the advantages of lithium-ion batteries and pseudocapacitive supercapacitors, possessing excellent rate performance, high energy density, high output power, long cycle life, safety, environmental friendliness, and relatively low cost, meeting the urgent needs of fast-charging consumer electronics and electric vehicles. However, HICs face a kinetic imbalance problem in practical applications, mainly due to the difference in energy storage mechanisms between their positive and negative electrodes, which severely restricts further performance improvements.

[0004] Therefore, to address the ever-increasing demand for energy storage, researchers are dedicated to developing novel energy storage materials to improve the performance and sustainability of energy storage devices. A series of new materials, including silicon-based composites, porous carbon / sulfur composites, and two-dimensional nanomaterials such as graphene, MoS2, and MXene, have emerged, offering new possibilities for solving the challenges in the energy storage field. In recent years, two-dimensional transition metal carbides, nitrides, and carbonitride layered materials, namely MXenes, have become one of the most promising emerging materials due to their unique two-dimensional structure, large specific surface area, and superior conductivity. Ti3C2 nanomaterials, as a member of the MXene family, have been favored by researchers for their ease of preparation and excellent environmental stability, especially in the field of energy storage. However, due to the van der Waals forces between layers, the stacking and aggregation of Ti3C2 nanosheets leads to a reduction in their electrochemical active area and an increase in the interlayer ion diffusion barrier, thus limiting the full realization of their excellent electrochemical performance. To overcome this problem, researchers have employed various methods to suppress interlayer interactions in Ti3C2, such as surface functionalization, organic cation intercalation, and heteroatom doping, to improve its electrochemical performance. Heteroatom doping is crucial for meeting the demand for high-capacity and long-life materials in practical applications because it can improve the electrical conductivity of MXene materials, widen the interlayer spacing to reduce the energy barrier for ion diffusion, and enhance environmental stability. This improvement not only effectively enhances the electrical conductivity of MXene but also optimizes its ion transport characteristics, thereby achieving superior performance in energy storage devices. In practical applications, this improvement is expected to provide strong support for the development and application of high-performance energy storage materials.

[0005] Among various heteroelements, nitrogen and phosphorus, due to their suitable elemental radii, can relatively easily occupy defect sites in MXene and replace MXene functional groups and C atoms, making them excellent candidates for MXene doping elements. Nitrogen-phosphorus co-doping helps to better increase the interlayer spacing of MXene and improves electrochemical performance (defect concentration / electron concentration) by introducing defects / distortions. In particular, the solvothermal non-in-situ doping method can preserve the structural integrity of MXene while allowing the modified material to inherit MXene's favorable layered structure; while nitrogen-phosphorus co-doping helps to improve the content and distribution of dopant elements in electrode materials, thereby strengthening the MXene structure. Overall, the introduction of nitrogen and phosphorus optimizes the interlayer spacing of MXene and increases the electron concentration, thus improving its conductivity. The application of the solvothermal nitrogen-phosphorus co-doping method further enhances this advantage while maintaining the integrity of the MXene's layered structure. This precise structural control helps improve the electrochemical performance of MXene, making it more suitable for high-efficiency energy storage devices.

[0006] Therefore, this patent aims to develop a high-performance nitrogen-phosphorus co-doped Ti3C2 nanomaterial and its preparation method, with the goal of expanding the interlayer spacing of Ti3C2 nanosheets, increasing surface active sites, and enhancing its charge storage capacity, thereby further achieving coordinated operation of the positive and negative electrodes of HICs and improving the overall performance of the device. This electrode material has the following characteristics: high power, rapid response, long lifespan, and safety and durability. Through the technological innovation of this patent, it is expected to overcome the kinetic imbalance problem of HICs, thereby further improving their performance in terms of high power density and long cycle life.

[0007] The preparation method of this anode material includes (but is not limited to) steps such as precisely controlling the material composition, optimizing the electrode structure, and employing novel synthesis processes. These methods ensure the effective application of the anode material in HICs, enabling synergistic work between electrodes and improving the overall system performance.

[0008] The technological innovation of this patent is expected to promote the application of hybrid supercapacitors in the field of fast charging, and provide more efficient, reliable and sustainable energy storage solutions for fields such as electric vehicles and consumer electronics. Summary of the Invention

[0009] The purpose of this invention is to provide a two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterial, a hybrid supercapacitor electrode, and a method for preparing the same. First, Ti, Al, and C powder raw materials are sintered in an atmosphere to form a Ti3AlC2 layered ceramic material. Then, using the Ti3AlC2 layered ceramic powder as a precursor, the Al layer is removed by etching with a mixed etching solution containing HCl / LiF ions to obtain high-quality Ti3C2 nanomaterials. Next, using the Ti3C2 nanomaterials as a matrix, nitrogen-phosphorus co-doping of Ti3C2 is achieved in situ using a solvothermal method with a mixed organic solution of melamine phosphate or piperazine phosphate, resulting in a nitrogen-phosphorus co-doped Ti3C2 layered material. This material is then fabricated into a capacitor electrode using an electrode preparation process and applied to a hybrid supercapacitor. The prepared electrode material exhibits excellent electrochemical performance.

[0010] 1. Two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials and their preparation method, including the following steps:

[0011] 1.1. Preparation of two-dimensional Ti3C2 nanomaterials

[0012] 1.1.1. Weigh the corresponding elemental raw material powders according to the molar ratio of Ti:Al:C = 3:1.2:2, and mechanically mix and grind them. Place the mixture in an alumina crucible and sinter at 1350℃ for 2 hours under argon or vacuum conditions at a heating rate of 10℃ per minute, then cool to room temperature at the same rate. Mechanically grind the sintered product to 400 mesh, which is the precursor Ti3AlC2 layered ceramic material.

[0013] 1.1.2. Two-dimensional Ti3C2 nanomaterials were obtained by liquid-phase etching of Ti3AlC2 using a mixed etching solution of appropriate concentration. In a fume hood, 2-4 g of LiF powder was added to 20-40 mL of concentrated hydrochloric acid with a mass concentration of 36-38%, and heated in an oil bath at 85-95℃ with stirring for 10 minutes. Subsequently, 1-2 g of the synthesized Ti3AlC2 powder was weighed and added to the mixed etching solution at 35-45℃, and stirred at 500-1000 rpm for 1-2 days.

[0014] 1.1.3. After etching is complete, place the mixture in a 50mL centrifuge tube. First, wash off excess fluoride with hydrochloric acid by centrifuging at 3500-4000rpm for 2-4 minutes, repeating 3 times. Then, add an appropriate amount of ultrapure water and centrifuge at 3500-4000rpm for 2-4 minutes to remove acidic waste liquid. Repeat this process several times until the pH of the supernatant is >5.

[0015] 1.1.4. By adding ultrapure water, place the black precipitate obtained by centrifugation into a 250mL blue-necked bottle, with a total volume of 50-150mL, and purify the liquid with 20mL·min⁻¹. -1 Argon gas was used to ultrasonically exfoliate the cells for 0.5-1 hour using an ultrasonic cell disruptor, followed by an ice bath. After ultrasonication, the cells were centrifuged at 1500-3500 rpm for 10-60 minutes to separate the layers, and the suspension was collected. The black suspension was freeze-dried, and the resulting black aerogel powder was the few-layer two-dimensional Ti3C2 nanomaterial.

[0016] 1.2. Preparation of two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials

[0017] 1.2.1. Using 5-10g of sodium tripolyphosphate or piperazine phosphate powder as the nitrogen and phosphorus sources, dissolve it in ethylene glycol to make a total solution volume of 30mL. Stir at room temperature for 30-60 minutes to ensure complete dissolution and uniform dispersion. Other nitrogen and phosphorus sources can be selected from these compounds, and the solution can be any organic solution capable of dissolving the corresponding nitrogen and phosphorus sources.

[0018] 1.2.2. Take 50-60 mg of Ti3C2 powder obtained in step 1.1 and place it in the above mixed organic solution. Stir at room temperature for 30-60 minutes to disperse it evenly. Place the mixed solution in a 50 mL PTFE-lined reactor and further place the fixed reactor in a high-precision CNC drying oven and react at 180-200℃ for 24-48 hours.

[0019] 1.2.3. After the reaction vessel has cooled, remove the mixed solution and clean the precipitate by centrifuging it with anhydrous ethanol and ultrapure water at 8000-10000 rpm for 5-10 minutes. Freeze-dry the black suspension to obtain the two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material.

[0020] 2. A two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material hybrid supercapacitor electrode and its preparation method, characterized by comprising the following steps:

[0021] 2.1. Weigh 1-20 mg of polyvinylidene fluoride powder and dissolve it in 0.25-5 mL of N-methylpyrrolidone solvent. Stir magnetically until a transparent, viscous mixture is formed. Add 4-80 mg of conductive carbon black to the mixture and stir for 30 minutes to form a uniform conductive slurry.

[0022] 2.2. Take 0.75-15 mg of two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material and add it to the slurry. Stir continuously for 1 hour to form a slightly viscous slurry.

[0023] 2.3. Using a pipette, transfer 15-25 μL of slurry and evenly drop it onto a clean, circular carbon cloth sheet with a radius of 6-12 mm. Dry under vacuum at 80-120℃ for 12 hours. The resulting product is the nitrogen-phosphorus co-doped Ti3C2 composite electrode. Calculate the mass of the electrode's active material loading by weighing the carbon cloth before and after the drop, which is approximately 1-6 mg / cm³. -2 .

[0024] 3. Electrode performance testing of two-dimensional nitrogen-phosphorus co-doped Ti3C2 hybrid supercapacitor

[0025] 3.1. Three-electrode testing system: A composite electrode with a diameter of 6-12 mm is used as the working electrode; the diameter is 12 mm, the thickness is 1-2 mm, and the mass per unit area is 25-40 mg / cm³. -2 An activated carbon electrode was used as the counter electrode; an Ag / AgCl electrode was used as the reference electrode. A three-way three-electrode system was assembled using sulfate aqueous solutions (lithium, sodium, magnesium, zinc, etc.) as the electrolyte. Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were performed using a Shanghai Chenhua CHI 660E electrochemical workstation to calculate the electrode specific capacity and rate performance.

[0026] 3.2. Two-electrode testing system: A composite electrode with a diameter of 6-12 mm was used as the negative electrode; based on the capacity and mass ratio, a certain diameter electrode with a unit area mass of 25-40 mg / cm² was used. -2The activated carbon electrode is used as the positive electrode, and the electrolyte is a sulfate aqueous solution (lithium, sodium, magnesium, zinc, etc.) or the corresponding organic electrolyte. The two-electrode system is assembled using a CR2032 button battery case. The CV, GCD, EIS and other performance tests are performed using a Shanghai Chenhua CHI 660E electrochemical workstation and a Blue Electric charge-discharge instrument. The electrode specific capacity, energy density, power density and cycle stability are calculated.

[0027] The beneficial effects of this invention are:

[0028] This invention uses two-dimensional Ti3C2 nanomaterials as a matrix to prepare two-dimensional nitrogen-phosphorus co-doped Ti3C2 composite electrode materials through non-in-situ solvothermal nitrogen-phosphorus co-doping with melamine phosphate or piperazine phosphate, and applies them to supercapacitors. The improvement of electrode material performance through solvothermal nitrogen-phosphorus co-doping was explored. Using nitrogen-phosphorus co-doping increases the interlayer spacing of MXene and the activation sites on the surface of the layered structure, which not only improves the material's conductivity but also enhances the utilization rate of its pseudocapacitive active sites, ultimately strengthening the electrochemical performance of the Ti3C2 composite electrode. In the field of energy storage, such as supercapacitors, the two-dimensional nitrogen-phosphorus co-doped Ti3C2 composite electrode material will provide a more efficient, reliable, and sustainable energy storage solution for electric vehicles and consumer electronics. Attached Figure Description

[0029] Figure 1 SEM image of the nitrogen-phosphorus co-doped Ti3C2 nanomaterial prepared by solvothermal processing of melamine phosphate in Example 1.

[0030] Figure 2 The image shows the XRD pattern of the nitrogen-phosphorus co-doped Ti3C2 nanomaterial prepared by solvothermal processing of melamine phosphate as described in Example 1.

[0031] Figure 3 The image shows the GCD of the Ti3C2 nanomaterials prepared in Example 1.

[0032] Figure 4 The image shows the GCD of the nitrogen-phosphorus co-doped Ti3C2 nanomaterials prepared by solvothermal processing with melamine phosphate in Example 1.

[0033] Figure 5 The long-cycle curve of the nitrogen-phosphorus co-doped Ti3C2 composite electrode prepared by solvothermal treatment with melamine phosphate in Example 1.

[0034] Figure 6 SEM image of nitrogen-phosphorus co-doped Ti3C2 nanomaterials prepared by solvothermal processing of piperazine phosphate in Example 2.

[0035] Figure 7 The GCD curve of the nitrogen-phosphorus co-doped Ti3C2 composite electrode prepared by solvothermal treatment of piperazine phosphate in Example 2.

[0036] Figure 8 The specific capacity of the Ti3C2 composite electrode, the nitrogen-phosphorus co-doped Ti3C2 composite electrode (MP-Ti3C2) prepared by solvothermal processing of melamine phosphate, and the nitrogen-phosphorus co-doped Ti3C2 composite electrode (Pi-Ti3C2) prepared by solvothermal processing of piperazine phosphate are compared in Example 2. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0038] Example 1:

[0039] 1. Two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials and their preparation method, including the following steps:

[0040] Step 1: Preparation of two-dimensional Ti3C2 nanomaterials;

[0041] First, the corresponding raw material powders were weighed and mixed and ground according to the molar ratio of Ti:Al:C = 3:1.2:2, and sintered at 1350℃ for 2 hours under argon atmosphere. After cooling, the sintered ceramic material was ground to 400 mesh to obtain the precursor Ti3AlC2 layered ceramic material.

[0042] Next, Ti3AlC2 was etched in a mixed etching solution to obtain two-dimensional Ti3C2 nanomaterials. 2g of LiF powder was added to 30mL of concentrated hydrochloric acid with a mass concentration of 36-38%, and stirred at room temperature for 10 minutes. Then, 1g of the synthesized Ti3AlC2 powder was weighed and added to the stirred solution. The mixture was placed in a fume hood, stirred at 1000rpm, and heated in an oil bath at 35℃ for one day.

[0043] Next, after etching is complete, place the etching mixture in a centrifuge tube, first wash off the excess LiF with concentrated hydrochloric acid, centrifuge at 3500 rpm for 2 minutes, repeat 3 times; add an appropriate amount of ultrapure water, centrifuge at 3500 rpm for 2 minutes to remove acidic waste liquid, repeat several times until the pH of the supernatant is >5.

[0044] Finally, by adding ultrapure water, the black precipitate obtained by centrifugation was placed in a 250mL blue-necked bottle, with a total volume of 50mL, and 20mL·min was bubbled into the liquid. -1 Argon gas was used to ultrasonically exfoliate the cells for 2 hours using an ultrasonic cell disruptor, followed by an ice bath. After ultrasonication, the cells were centrifuged at 1500 rpm for 30 minutes to separate the layers, and the suspension was collected. The black suspension was freeze-dried, and the resulting black aerogel powder was the exfoliated two-dimensional Ti3C2 nanomaterial.

[0045] Step 2: Preparation of two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials;

[0046] First, 5g of melamine phosphate powder was used as the nitrogen and phosphorus source and dissolved in ethylene glycol to make a total solution volume of 30mL. The solution was stirred at room temperature for 30 minutes to ensure it was fully dissolved and evenly dispersed.

[0047] Next, take 50 mg of Ti3C2 powder obtained in step one and place it in the above mixed organic solution. Stir at room temperature for 30 minutes to disperse it evenly. Place the mixed solution in a 50 mL tetrafluoroethylene-lined reactor and further place the fixed reactor in a high-precision CNC drying oven and react at 200°C for 48 hours.

[0048] Finally, the mixed solution was removed, and the precipitate was washed by centrifugation with anhydrous ethanol and ultrapure water at 8000-10000 rpm for 10 minutes, and repeated 3 times. The black suspension was then freeze-dried, and the product was the two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material.

[0049] The SEM image of the two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material prepared in this embodiment is shown below. Figure 1 As shown, Ti3C2 retains a size of approximately 2.5 μm after a solvothermal reaction in melamine phosphate solution, indicating its good structural stability. The XRD pattern of the two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material prepared in this example is shown below. Figure 2 As shown, compared with Ti3C2, the (002) peak of nitrogen-phosphorus co-doped Ti3C2 shifts to the right, indicating that it has a larger interlayer spacing.

[0050] 2. A method for preparing a composite electrode from a two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material, characterized by comprising the following steps:

[0051] First, weigh 10 mg of polyvinylidene fluoride powder, dissolve it in 0.25 mL of N-methylpyrrolidone solvent, and stir magnetically until a transparent and viscous mixture is formed.

[0052] Next, add 10 mg of conductive carbon black to the above mixture and stir for 30 minutes to form a uniform slurry;

[0053] Subsequently, 5 mg of two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material was added to the slurry and stirred continuously for 1 hour to form a slightly viscous slurry.

[0054] Next, 15 μL of slurry was pipetted evenly onto a clean circular carbon cloth sheet with a diameter of 6 mm, and vacuum dried at 80 °C for 12 hours to obtain the nitrogen-phosphorus co-doped Ti3C2 composite electrode.

[0055] Finally, by weighing the carbon cloth before and after the addition, the mass of the electrode active material loaded was calculated to be approximately 2 mg / cm³. -2 .

[0056] 3. Performance testing of two-dimensional nitrogen-phosphorus co-doped Ti3C2-based electrodes;

[0057] Three-electrode testing system: A composite electrode with a diameter of 6 mm was used as the working electrode; the diameter was 6 mm, the thickness was 2 mm, and the mass per unit area was 30 mg·cm³. -2 An activated carbon electrode was used as the counter electrode; an Ag / AgCl electrode was used as the reference electrode. A three-electrode system was assembled using 1M Na2SO4 solution as the electrolyte. CV, GCD, and EIS tests were performed using a Shanghai Chenhua CHI 660E electrochemical workstation, and the electrode specific capacity was calculated.

[0058] The GCD curve measured using a three-electrode system in 1M Na2SO4 is shown below. Figure 3 As shown. With Figure 4 Compared to the GCD curve of the Ti3C2 nanocomposite electrode shown, the two-dimensional nitrogen-phosphorus co-doped Ti3C2-based electrode prepared in this embodiment has a longer charge-discharge time. This is because the entry of nitrogen and phosphorus elements into the Ti3C2 lattice or substitution of functional groups significantly improves the conductivity of Ti3C2, while introducing more surface active sites, giving it a higher specific capacity.

[0059] Two-electrode testing system: A composite electrode with a diameter of 12 mm was used as the negative electrode; the diameter was 12 mm, the thickness was 2 mm, and the mass per unit area was 30 mg·cm³. -2 The activated carbon electrode was used as the positive electrode, and 1M Na2SO4 solution was used as the electrolyte. The two-electrode system was assembled using a CR2032 button battery case. The performance of the electrode was tested using a Shanghai Chenhua CHI 660E electrochemical workstation and a Blue Electric charge-discharge instrument, including CV, GCD, and EIS. The electrode specific capacity, energy density, power density, and cycle stability were calculated.

[0060] Figure 5 The long-cycle curve of the material prepared in this example was measured in a two-electrode system at 1 A g. -1 After undergoing 5000 cycles, it can still maintain about 75% of its original specific capacity, indicating that it has a certain degree of cycle stability.

[0061] Example 2:

[0062] 1. Two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials and their preparation method, including the following steps:

[0063] Step 1: Preparation of two-dimensional Ti3C2 nanomaterials;

[0064] First, the corresponding raw material powders were weighed and mixed and ground according to the molar ratio of Ti:Al:C = 3:1.2:2, and sintered at 1350℃ for 2 hours under argon atmosphere. After cooling, the sintered ceramic material was ground to 400 mesh to obtain the precursor Ti3AlC2 layered ceramic material.

[0065] Next, Ti3AlC2 was etched in a mixed etching solution to obtain two-dimensional Ti3C2 nanomaterials. 4g of LiF powder was added to 20mL of concentrated hydrochloric acid (36-38% by mass) and stirred at room temperature for 10 minutes. Then, 2g of the synthesized Ti3AlC2 powder was weighed and added to the stirred solution. The mixture was placed in a fume hood, stirred at 1000rpm, and heated in an oil bath at 40℃ for one day.

[0066] Next, after etching is complete, place the etching mixture in a centrifuge tube, first wash off the excess LiF with concentrated hydrochloric acid, centrifuge at 3500 rpm for 2 minutes, repeat 3 times; add an appropriate amount of ultrapure water, centrifuge at 3500 rpm for 2 minutes to remove acidic waste liquid, repeat several times until the pH of the supernatant is >5.

[0067] Finally, by adding ultrapure water, the black precipitate obtained by centrifugation was placed in a 250mL blue-necked bottle, with a total volume of 50mL, and 20mL·min was bubbled into the liquid. -1 Argon gas was used to ultrasonically exfoliate the cells for 2 hours using an ultrasonic cell disruptor, followed by an ice bath. After ultrasonication, the cells were centrifuged at 1500 rpm for 30 minutes to separate the layers, and the suspension was collected. The black suspension was freeze-dried, and the resulting black aerogel powder was the exfoliated two-dimensional Ti3C2 nanomaterial.

[0068] Step 2: Preparation of two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials;

[0069] First, 5g of piperazine phosphate powder was used as the nitrogen and phosphorus source and dissolved in ethylene glycol to make a total solution volume of 30mL. The solution was stirred at room temperature for 30 minutes to ensure it was fully dissolved and evenly dispersed.

[0070] Next, take 60 mg of Ti3C2 powder obtained in step one and place it in the above mixed organic solution. Stir at room temperature for 30 minutes to disperse it evenly. Place the mixed solution in a 50 mL PTFE-lined reactor and further place the fixed reactor in a high-precision CNC drying oven and react at 200°C for 48 hours.

[0071] Finally, the mixed solution was removed, and the precipitate was washed by centrifugation at 8000 rpm for 10 minutes with anhydrous ethanol and ultrapure water, respectively. This process was repeated 3 times. The black suspension was then freeze-dried, and the product was the two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material.

[0072] The SEM image of the two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material prepared in this embodiment is shown below. Figure 6 As shown, Ti3C2 retains a size of approximately 45 μm after a solvothermal reaction in piperazine phosphate solution, indicating its good structural stability. Compared to the two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material prepared in Example 1, this example exhibits a larger nanosheet size, indicating higher conductivity and facilitating the rapid migration of electrolyte ions on the nanosheet surface.

[0073] 2. A method for preparing a composite electrode from a two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material, characterized by comprising the following steps:

[0074] First, weigh 15 mg of polyvinylidene fluoride powder, dissolve it in 0.25 mL of N-methylpyrrolidone solvent, and stir magnetically until a transparent and viscous mixture is formed.

[0075] Next, add 10 mg of conductive carbon black to the above mixture and stir for 30 minutes to form a uniform slurry;

[0076] Subsequently, 15 mg of two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material was added to the slurry and stirred continuously for 1 hour to form a slightly viscous slurry.

[0077] Next, 15 μL of slurry was pipetted evenly onto a clean circular carbon cloth sheet with a diameter of 6 mm, and vacuum dried at 80 °C for 12 hours to obtain the nitrogen-phosphorus co-doped Ti3C2 composite electrode.

[0078] Finally, the mass of the electrode active material was calculated by weighing the carbon cloth before and after its addition.

[0079] 3. Performance testing of two-dimensional nitrogen-phosphorus co-doped Ti3C2-based electrodes;

[0080] Three-electrode testing system: A composite electrode with a diameter of 6 mm was used as the working electrode; the diameter was 6 mm, the thickness was 2 mm, and the mass per unit area was 30 mg·cm³. -2 An activated carbon electrode was used as the counter electrode; an Ag / AgCl electrode was used as the reference electrode. A three-electrode system was assembled using 1M Na2SO4 solution as the electrolyte. CV, GCD, and EIS tests were performed using a Shanghai Chenhua CHI 660E electrochemical workstation, and the electrode specific capacity was calculated.

[0081] The GCD curve measured in 1M Na2SO4 using a three-electrode system in this example is shown below. Figure 7 As shown. Compared with the GCD curve of the Ti3C2 nanocomposite electrode, the two-dimensional nitrogen-phosphorus co-doped Ti3C2-based electrode prepared in this example has a longer charge-discharge time, indicating that it has a higher specific capacity. Furthermore, as... Figure 8The two-dimensional nitrogen-phosphorus co-doped Ti3C2-based electrode prepared in this embodiment has a higher specific capacitance than the Ti3C2 electrode at different current densities, indicating that nitrogen-phosphorus co-doping endows it with enhanced capacitance performance.

[0082] Two-electrode testing system: A composite electrode with a diameter of 12 mm was used as the negative electrode; the diameter was 12 mm, the thickness was 2 mm, and the mass per unit area was 30 mg·cm³. -2 The activated carbon electrode was used as the positive electrode, and 1M Na2SO4 solution was used as the electrolyte. The two-electrode system was assembled using a CR2032 button battery case. The performance of the electrode was tested using a Shanghai Chenhua CHI 660E electrochemical workstation and a Blue Electric charge-discharge instrument, including CV, GCD, and EIS. The electrode specific capacity, energy density, power density, and cycle stability were calculated.

[0083] Example 3:

[0084] 1. Two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials and their preparation method, including the following steps:

[0085] Step 1: Preparation of two-dimensional Ti3C2 nanomaterials;

[0086] First, the corresponding raw material powders were weighed and mixed and ground according to the molar ratio of Ti:Al:C = 3:1.2:2, and sintered at 1350℃ for 2 hours under argon atmosphere. After cooling, the sintered ceramic material was ground to 400 mesh to obtain the precursor Ti3AlC2 layered ceramic material.

[0087] Next, Ti3AlC2 was etched in a mixed etching solution to obtain two-dimensional Ti3C2 nanomaterials. 2g of LiF powder was added to 25mL of concentrated hydrochloric acid (36-38% by mass) and stirred at room temperature for 10 minutes. Then, 1g of the synthesized Ti3AlC2 powder was weighed and added to the stirred solution. The mixture was placed in a fume hood, stirred at 500rpm, and heated in an oil bath at 35℃ for one day.

[0088] Next, after etching is complete, place the etching mixture in a centrifuge tube, first wash off the excess LiF with concentrated hydrochloric acid, centrifuge at 4000 rpm for 2 minutes, repeat 3 times; add an appropriate amount of ultrapure water, centrifuge at 4000 rpm for 2 minutes to remove acidic waste liquid, repeat several times until the pH of the supernatant is >5.

[0089] Finally, by adding ultrapure water, the black precipitate obtained by centrifugation was placed in a 250mL blue-necked bottle, with a total volume of 100mL, and 20mL·min was bubbled into the liquid. -1Argon gas was used to ultrasonically exfoliate the cells for 2 hours using an ultrasonic cell disruptor, followed by an ice bath. After ultrasonication, the cells were centrifuged at 3500 rpm for 30 minutes to separate the layers, and the suspension was collected. The black suspension was freeze-dried, and the resulting black aerogel powder was the exfoliated two-dimensional Ti3C2 nanomaterial.

[0090] Step 2: Preparation of two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials;

[0091] First, 10g of piperazine phosphate powder was used as the nitrogen and phosphorus source and dissolved in ethylene glycol to make a total solution volume of 30mL. The solution was stirred at room temperature for 30 minutes to ensure it was fully dissolved and evenly dispersed.

[0092] Next, take 55 mg of Ti3C2 powder obtained in step one and place it in the above mixed organic solution. Stir at room temperature for 30 minutes to disperse it evenly. Place the mixed solution in a 50 mL PTFE-lined reactor and further place the fixed reactor in a high-precision CNC drying oven and react at 200°C for 48 hours.

[0093] Finally, the mixed solution was removed, and the precipitate was washed by centrifugation at 10,000 rpm for 10 minutes with anhydrous ethanol and ultrapure water, respectively. This process was repeated 3 times. The black suspension was then freeze-dried, and the product was the two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material.

[0094] 2. A method for preparing a composite electrode from a two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material, characterized by comprising the following steps:

[0095] First, weigh 10 mg of polyvinylidene fluoride powder, dissolve it in 0.25 mL of N-methylpyrrolidone solvent, and stir magnetically until a transparent and viscous mixture is formed.

[0096] Next, add 10 mg of conductive carbon black to the above mixture and stir for 30 minutes to form a uniform slurry;

[0097] Subsequently, 15 mg of two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material was added to the slurry and stirred continuously for 1 hour to form a slightly viscous slurry.

[0098] Next, 15 μL of slurry was pipetted evenly onto a clean circular carbon cloth sheet with a diameter of 6 mm, and vacuum dried at 80 °C for 12 hours to obtain the nitrogen-phosphorus co-doped Ti3C2 composite electrode.

[0099] Finally, the mass of the electrode active material was calculated by weighing the carbon cloth before and after its addition.

[0100] 3. Performance testing of two-dimensional nitrogen-phosphorus co-doped Ti3C2-based electrodes;

[0101] Three-electrode testing system: A composite electrode with a diameter of 6 mm was used as the working electrode; the diameter was 6 mm, the thickness was 2 mm, and the mass per unit area was 35 mg·cm³. -2 An activated carbon electrode was used as the counter electrode; an Ag / AgCl electrode was used as the reference electrode. A three-electrode system was assembled using 1M Na2SO4 solution as the electrolyte. CV, GCD, and EIS tests were performed using a Shanghai Chenhua CHI 660E electrochemical workstation, and the electrode specific capacity was calculated.

[0102] Two-electrode testing system: A composite electrode with a diameter of 12 mm was used as the negative electrode; the diameter was 12 mm, the thickness was 2 mm, and the mass per unit area was 35 mg·cm³. -2 The activated carbon electrode was used as the positive electrode, and 1M Na2SO4 solution was used as the electrolyte. The two-electrode system was assembled using a CR2032 button battery case. The performance of the electrode was tested using a Shanghai Chenhua CHI 660E electrochemical workstation and a Blue Electric charge-discharge instrument, including CV, GCD, and EIS. The electrode specific capacity, energy density, power density, and cycle stability were calculated.

[0103] Example 4:

[0104] 1. Two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials and their preparation method, including the following steps:

[0105] Step 1: Preparation of two-dimensional Ti3C2 nanomaterials;

[0106] First, the corresponding raw material powders were weighed and mixed and ground according to the molar ratio of Ti:Al:C = 3:1.2:2, and sintered at 1350℃ for 2 hours under argon atmosphere. After cooling, the sintered ceramic material was ground to 400 mesh to obtain the precursor Ti3AlC2 layered ceramic material.

[0107] Next, Ti3AlC2 was etched in a mixed etching solution to obtain two-dimensional Ti3C2 nanomaterials. 2g of LiF powder was added to 25mL of concentrated hydrochloric acid (36-38% by mass) and stirred at room temperature for 10 minutes. Then, 1g of the synthesized Ti3AlC2 powder was weighed and added to the stirred solution. The mixture was placed in a fume hood, stirred at 800rpm, and heated in an oil bath at 35℃ for one day.

[0108] Next, after etching is complete, place the etching mixture in a centrifuge tube, first wash off the excess LiF with concentrated hydrochloric acid, centrifuge at 4000 rpm for 2 minutes, repeat 3 times; add an appropriate amount of ultrapure water, centrifuge at 3500 rpm for 2 minutes to remove acidic waste liquid, repeat several times until the pH of the supernatant is >5.

[0109] Finally, by adding ultrapure water, the black precipitate obtained by centrifugation was placed in a 250mL blue-necked bottle, with a total volume of 100mL, and 20mL·min was bubbled into the liquid. -1 Argon gas was used to ultrasonically exfoliate the cells for 2 hours using an ultrasonic cell disruptor, followed by an ice bath. After ultrasonication, the cells were centrifuged at 3500 rpm for 30 minutes to separate the layers, and the suspension was collected. The black suspension was freeze-dried, and the resulting black aerogel powder was the exfoliated two-dimensional Ti3C2 nanomaterial.

[0110] Step 2: Preparation of two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials;

[0111] First, 10g of melamine phosphate powder was used as the nitrogen and phosphorus source and dissolved in ethylene glycol to make a total solution volume of 30mL. The solution was stirred at room temperature for 20 minutes to ensure it was fully dissolved and evenly dispersed.

[0112] Next, take 60 mg of Ti3C2 powder obtained in step one and place it in the above mixed organic solution. Stir at room temperature for 30 minutes to disperse it evenly. Place the mixed solution in a 50 mL PTFE-lined reactor and further place the fixed reactor in a high-precision CNC drying oven and react at 200°C for 48 hours.

[0113] Finally, the mixed solution was removed, and the precipitate was washed by centrifugation at 8000 rpm for 10 minutes with anhydrous ethanol and ultrapure water, respectively. This process was repeated 3 times. The black suspension was then freeze-dried, and the product was the two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material.

[0114] 2. A method for preparing a composite electrode from a two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material, characterized by comprising the following steps:

[0115] First, weigh 10 mg of polyvinylidene fluoride powder, dissolve it in 0.25 mL of N-methylpyrrolidone solvent, and stir magnetically until a transparent and viscous mixture is formed.

[0116] Next, add 10 mg of conductive carbon black to the above mixture and stir for 30 minutes to form a uniform slurry;

[0117] Subsequently, 15 mg of two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material was added to the slurry and stirred continuously for 1 hour to form a slightly viscous slurry.

[0118] Next, 15 μL of slurry was pipetted evenly onto a clean circular carbon cloth sheet with a diameter of 6 mm, and vacuum dried at 80 °C for 12 hours to obtain the nitrogen-phosphorus co-doped Ti3C2 composite electrode.

[0119] Finally, the mass of the electrode active material was calculated by weighing the carbon cloth before and after its addition.

[0120] 3. Performance testing of two-dimensional nitrogen-phosphorus co-doped Ti3C2-based electrodes;

[0121] Three-electrode testing system: A composite electrode with a diameter of 6 mm was used as the working electrode; the diameter was 6 mm, the thickness was 2 mm, and the mass per unit area was 35 mg·cm³. -2 An activated carbon electrode was used as the counter electrode; an Ag / AgCl electrode was used as the reference electrode. A three-electrode system was assembled using 1M Na2SO4 solution as the electrolyte. CV, GCD, and EIS tests were performed using a Shanghai Chenhua CHI 660E electrochemical workstation, and the electrode specific capacity was calculated.

[0122] Two-electrode testing system: A composite electrode with a diameter of 12 mm was used as the negative electrode; the diameter was 12 mm, the thickness was 2 mm, and the mass per unit area was 40 mg·cm³. -2 The activated carbon electrode was used as the positive electrode, and 1M Na2SO4 solution was used as the electrolyte. The two-electrode system was assembled using a CR2032 button battery case. The performance of CV, GCD, EIS and other tests were performed using a Shanghai Chenhua CHI660E electrochemical workstation and a Blue Electric charge-discharge instrument. The electrode specific capacity, energy density, power density and cycle stability were calculated.

Claims

1. A method for preparing two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials, characterized in that, Includes the following steps: Step 1: Preparation of two-dimensional few-layer Ti3C2 nanomaterials; First, the corresponding raw material powders were weighed and mixed and ground according to the molar ratio of Ti:Al:C = 3:1.2:

2. The mixture was sintered at 1350 °C for 2 hours under argon atmosphere. After cooling, the sintered ceramic material was ground to 400 mesh to obtain the precursor Ti3AlC2 layered ceramic material. Secondly, Ti3AlC2 was etched in a mixed etching solution to obtain two-dimensional Ti3C2 nanomaterials: 2-8 g of LiF powder was added to 20-40 mL of concentrated hydrochloric acid with a mass concentration of 36-38%, and stirred at room temperature for 10-30 minutes; then, 1-4 g of the synthesized Ti3AlC2 powder was weighed and added to the mixed etching solution, placed in a fume hood, magnetically stirred at 500-1000 rpm, heated in an oil bath at 35-45℃, and etched for 1-2 days. Next, after etching is complete, place the etching mixture in a centrifuge tube and wash away excess LiF with concentrated hydrochloric acid. Centrifuge at 3500-4000 rpm for 2-4 minutes and repeat 3 times. Add an appropriate amount of ultrapure water and centrifuge at 3500-5000 rpm for 2-4 minutes to remove acidic waste liquid. Repeat several times until the pH of the supernatant is >5. Finally, by adding ultrapure water, the black precipitate obtained by centrifugation was placed in a 250 mL blue-necked bottle, with a total volume of 50-150 mL, and 20 mL of water was bubbled into the liquid. min -1 Argon gas was used to ultrasonically exfoliate the cells for 1-2 hours using an ultrasonic cell disruptor, followed by an ice bath. After ultrasonication, the cells were centrifuged at 1500-3500 rpm for 10-60 minutes to separate the layers, and the suspension was collected. The black suspension was freeze-dried, and the resulting black aerogel powder was the exfoliated two-dimensional few-layer Ti3C2 nanomaterial. Step 2: Preparation of two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials; First, use 5-10 g of melamine phosphate or piperazine phosphate as the nitrogen and phosphorus source, dissolve it in ethylene glycol to make the total volume of the solution 30 mL, and stir at room temperature for 30-60 minutes to make it fully dissolved and evenly dispersed. Next, take 50-150 mg of Ti3C2 powder obtained in step one and place it in the above mixed solution. Stir at room temperature for 30-60 minutes to disperse it evenly. Place the mixed solution in a 50 mL tetrafluoroethylene-lined and reaction vessel. Then place the fixed reaction vessel in a high-precision CNC drying oven and react at 180-200 ℃ for 24-48 hours. Finally, the mixed solution was removed, and the precipitate was washed clean by centrifugation at 8000-10000 rpm for 5-10 minutes with anhydrous ethanol and ultrapure water, respectively. The black suspension was then freeze-dried, and the product was the two-dimensional nitrogen-phosphorus co-doped Ti3C2 layered material.

2. A method for preparing hybrid supercapacitor electrodes using two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanomaterials, characterized in that, Includes the following steps: First, weigh 1-20 mg of polyvinylidene fluoride powder, dissolve it in 0.25-5 mL of N-methylpyrrolidone solvent, and stir magnetically until a transparent and viscous mixture is formed. Next, add 4-80 mg of conductive carbon black to the above mixture and stir for 30 minutes to form a uniform slurry; Next, 0.75-15 mg of two-dimensional nitrogen-phosphorus co-doped Ti3C2 nanoparticles prepared by the method described in claim 1 are added to the slurry and stirred continuously for 0.5-2 hours to form a viscous slurry; Then, use a pipette to transfer 15-25 μL of slurry and evenly drop it onto a clean circular carbon cloth sheet with a radius of 6-12 mm. Dry it under vacuum at 80-120 ℃ for 12-48 hours. The result is the nitrogen-phosphorus co-doped Ti3C2 supercapacitor electrode. Finally, by weighing the carbon cloth before and after the addition, the mass of the electrode active material per unit area was calculated to be 1-6 mg / cm³. -2 .

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