Three-dimensional flower-shaped carbon-supported CuNb2O6 material as well as preparation method and application thereof

Abstract

The invention provides a three-dimensional flower-shaped carbon-supported CuNb2O6 material as well as a preparation method and application thereof, and belongs to the technical field of electrochemical devices. The preparation method of the three-dimensional flower-shaped carbon-supported CuNb2O6 material comprises the following steps: dissolving a niobium source, a copper source and a surfactant in a solvent, and stirring and mixing to obtain a precursor solution; adding carbon nanoflowers into the precursor solution for reaction, and after the reaction is finished, evaporating the solvent to dryness to obtain a CuNb2O6 precursor; the CuNb2O6 precursor is subjected to calcination treatment, cooling, washing and freeze drying, and the three-dimensional flower-shaped carbon-supported CuNb2O6 material is prepared. The supporting effect of the three-dimensional flower-shaped carbon network in the prepared composite material effectively improves the specific capacity of the composite material, and the addition of Cu obviously enhances the conductivity of Nb2O5, so that the impedance is reduced. The cycling stability and the rapid charging capability of the CuNb2O6 negative electrode material in a lithium ion capacitor are effectively improved through the synergistic effect of the three-dimensional carbon network and Cu, and the method is simple, low in cost and capable of achieving large-scale production.

Description

Technical Field

[0001] This invention belongs to the technical field of electrochemical devices, and particularly relates to a CuNb2O6 material. Background Technology

[0002] The widespread commercialization of electric vehicles is currently hampered by the long charging times and safety issues of existing lithium-ion batteries. Therefore, it is essential to develop a new generation of lithium-ion batteries for transportation and everyday applications that offer high rate performance, a safe operating voltage window, and long cycle life. The charge / discharge rate of a battery depends on the inherent ion and electron transport characteristics of the electrode materials, as well as the electrode and battery structure. Traditional lithium-ion battery anode materials (such as graphite and silicon) have limited rate capability, primarily due to the formation of dendritic lithium and excessive volume expansion. For example, graphite experiences significant capacity loss at high cycle rates. Furthermore, dendritic lithium formation at low voltages can cause internal short circuits or even explosions. During cycling, silicon-based anode materials undergo significant volume changes, leading to material pulverization and a rapid capacity decline. In terms of fast charging, niobium compounds have emerged as a potential next-generation fast-charging material due to their higher intercalation capability and better rate capability, while maintaining excellent safety within a potential window of 1.0–3.0 V. Intrinsic conductivity can be improved through material modification and / or integration with other more conductive two-dimensional materials. Publication No. CN119170779A discloses a method of coating niobium-based anode materials with a high dielectric constant. When the high dielectric constant material is composed of BaTiO3 or similar components, the rate performance of the anode can be significantly improved, while the surface of the anode material can be further stabilized. The coating material increases the local electric field on the anode surface, thereby enhancing the electrochemical performance of the material. Furthermore, the titanium contained in this high dielectric constant material has the characteristic of diffusing into the niobium-based material during the coating process, which can suppress electrolyte decomposition and surface side reactions during fast charging, thus improving the stability of the material's surface structure. Similarly, finding a material with a relatively high dielectric constant to combine with niobium-based materials to improve their conductivity is an effective way to enhance their rate performance and cycle performance. Summary of the Invention

[0003] To address the technical problems of high production cost of negative electrode materials and low charging rate as electrode materials for supercapacitors, this invention proposes a three-dimensional flower-shaped carbon-supported CuNb2O6 material, its preparation method, and its application. Using a three-dimensional flower-shaped carbon network as the matrix, a simple, environmentally friendly, low-temperature, and large-scale method is employed to prepare the three-dimensional flower-shaped carbon-supported CuNb2O6 material. The prepared three-dimensional flower-shaped carbon-supported CuNb2O6 material has high specific surface area and high conductivity, achieving relatively fast charge and discharge capabilities, and can be used as a supercapacitor electrode material with excellent capacitance performance.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0005] A three-dimensional flower-like carbon-supported CuNb2O6 material is prepared by the following steps:

[0006] (1) Dissolve the niobium source, surfactant and copper source in a solvent and stir to obtain a precursor solution;

[0007] (2) Add carbon nanoflowers to the precursor solution and ultrasonically disperse for 10-20 min to carry out the reaction. After the reaction is completed, evaporate the solvent to obtain CuNb2O6 precursor.

[0008] (3) The CuNb2O6 precursor was calcined, cooled, washed, and freeze-dried to obtain a three-dimensional flower-shaped carbon-supported CuNb2O6 material.

[0009] The niobium source is niobium oxide and / or niobium oxalate; the surfactant is one or more of hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, or dodecyltrimethylammonium bromide; the copper source is one or more of copper oxide, copper nitrate, copper chloride, copper sulfate, or copper acetate; and the solvent is deionized water or a mixture of deionized water and alcohol.

[0010] The alcohol is one or more of methanol, ethanol, and propanol.

[0011] Preferably, the surfactant is hexadecyltrimethylammonium bromide (CTAB), a cationic surfactant whose molecular structure contains a hydrophilic head group and a hydrophobic tail group, enabling it to form a micelle structure in solution. Simultaneously, CTAB, as a surfactant, helps to achieve uniform distribution and controlled growth of metal ions, thereby improving the crystallinity and uniformity of the synthesized material.

[0012] The mass ratio of the copper source, niobium source, and surfactant is 1:1-3:0.1-1; the concentration of the niobium source in the precursor solution is 0.1-5 wt%.

[0013] The ratio of the amount of carbon nanoflowers added in step (2) to the mass ratio of the copper source in step (1) is 1:0.5-2.

[0014] The carbon nanoflowers are prepared by mixing a carbon source and a pore-forming agent in a mass ratio of 1:2-5 and then activating and calcining them at 800-1000℃ for 1-10 hours.

[0015] The carbon source is a biomass carbon source; the biomass carbon source is coconut shell charcoal, bamboo charcoal, or wood chip charcoal; the pore-forming agent is a carbonate; the carbonate is one or more of potassium carbonate, sodium carbonate, calcium carbonate, sodium bicarbonate, or potassium bicarbonate.

[0016] The reaction temperature in step (2) is 60-80 ℃ and the time is 10-30 min.

[0017] The drying temperature is 60-80 ℃, and the drying time is 8-24 h.

[0018] The calcination process is carried out in an inert gas atmosphere, with a heating rate of 5 °C / min, a temperature of 800-900 °C, and a holding time of 1-5 h.

[0019] The inert gas is one of nitrogen, argon, or a combination thereof.

[0020] In step (3), acid and deionized water are used for washing until the solution becomes neutral.

[0021] An electrode is prepared by mixing a three-dimensional flower-shaped carbon-supported CuNb2O6 material, a conductive agent, and a binder, coating the mixture onto a current collector, drying it overnight, and cutting it into circular discs with a loading of 1.5-2 mg / cm³. 2 .

[0022] The conductive agent is acetylene black, carbon black, Ketjen black, carbon nanotubes, or graphite powder; the binder is polyvinylidene fluoride, polytetrafluoroethylene, carboxymethyl cellulose, or polyvinyl alcohol; and the current collector is copper foil.

[0023] The evaluation method for the electrode is to assemble a lithium-ion half-cell in an RS2023 battery case using a lithium sheet as the counter electrode, lithium hexafluorophosphate as the electrolyte, and a polyethylene microporous membrane as the separator.

[0024] A lithium-ion capacitor includes a positive electrode, a negative electrode, a separator, and an electrolyte.

[0025] The negative electrode is an electrode disclosed in this invention.

[0026] The positive electrode uses three-dimensional porous flower-like carbon as the positive electrode material. The preparation method of the positive electrode sheet is as follows: carbon nanoflowers, conductive agent, and binder are mixed and coated onto aluminum foil, dried overnight, and cut into circular sheets. The current collector is replaced with aluminum foil, and the rest are the same. The circular sheets are cut with a loading of 2.0-2.2 mg / cm³. 2 .

[0027] The diaphragm is a polyethylene microporous diaphragm.

[0028] The electrolyte is lithium hexafluorophosphate.

[0029] The beneficial effects of this invention are:

[0030] (1) The single-phase CuNb2O6 bimetallic oxide prepared by the present invention fully retains the advantages of hexagonal niobium oxide, such as high chemical stability, suitable lithium intercalation potential, and small charge-discharge volume deformation. At the same time, the introduction of copper element optimizes the electronic band structure of the material, significantly improves the intrinsic conductivity, and improves the problem of limited electrochemical reaction kinetics of traditional niobium-based oxides.

[0031] (2) This invention uses three-dimensional flower-like porous carbon as a supporting matrix to construct a hierarchical porous composite system. The continuous carbon network provides a through-through high-speed electron conduction pathway, which forms a strong synergy with the intrinsic conductivity improvement brought about by copper modification. The rich porous structure and high specific surface area not only greatly increase the contact area between the active material and the electrolyte and provide sufficient reactive sites, but also significantly shorten the lithium ion diffusion distance. The rigid carbon skeleton can effectively buffer the volume deformation during the charging and discharging process, inhibit the agglomeration, pulverization and shedding of the active material, and structurally ensure the long cycle life of the material.

[0032] (3) The material of this invention, as a negative electrode for lithium-ion batteries, exhibits significantly better overall performance than pure-phase CuNb2O6. The optimal ratio sample achieves a discharge specific capacity of up to 407.3 mAh·g at a 0.1C rate. -1 It nearly doubles the performance of pure-phase materials; it still maintains 110.8 mAh·g at an ultra-high rate of 50C. -1 The reversible specific capacity and rate performance have achieved a breakthrough improvement; after 1000 cycles at a high rate of 10C, the capacity retention rate is as high as 95.1%, which is far superior to pure phase CuNb2O6 (71.3%), and the cycle stability is excellent.

[0033] (4) The material of this invention combines the high specific capacity of battery-type lithium intercalation energy storage with the fast charge-discharge characteristics of capacitor-type energy storage, matching the energy storage requirements of lithium-ion capacitors. Devices assembled based on this material have low charge transfer resistance and excellent electrochemical reversibility, with a charge transfer resistance of 0.5 A·g. -1 The specific capacitance at current density is as high as 302 F·g -1 8 A・g -1 It still maintains 97 F·g under high current density -1 The specific capacitance successfully balances high energy density and high power density.

[0034] (5) The raw materials used in this invention are widely available and inexpensive. The process is simple and does not require high-end equipment or stringent reaction conditions. The product has high phase purity and good batch stability. It can be widely used in multiple new energy scenarios such as power energy storage, portable electronic devices, and grid-level energy storage. The industrial application prospects are broad. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a scanning electron microscope image of the three-dimensional flower-shaped carbon-supported CuNb2O6 material prepared in Example 1.

[0037] Figure 2 The X-ray diffraction spectra of the three-dimensional flower-shaped carbon-supported CuNb2O6 materials prepared in Examples 1-3 and the CuNb2O6 material prepared in Comparative Example 1 are shown.

[0038] Figure 3 The charge-discharge curves of the three-dimensional flower-shaped carbon-supported CuNb2O6 materials prepared in Examples 1-3 and the CuNb2O6 material prepared in Comparative Example 1 at 0.1C are shown.

[0039] Figure 4 The graphs show the rate of change of the three-dimensional flower-shaped carbon-supported CuNb2O6 materials prepared in Examples 1-3 and the CuNb2O6 material prepared in Comparative Example 1 at 0.1-50°C.

[0040] Figure 5 The graphs show the cycling performance of the three-dimensional flower-shaped carbon-supported CuNb2O6 materials prepared in Examples 1-3 and the CuNb2O6 material prepared in Comparative Example 1 at 0.5C.

[0041] Figure 6 The graphs show the cycling performance of the three-dimensional flower-shaped carbon-supported CuNb2O6 materials prepared in Examples 1-3 and the CuNb2O6 material prepared in Comparative Example 1 at 10C.

[0042] Figure 7 Impedance diagram of the CuNb2O6@C / / PFC lithium-ion capacitor device prepared in Example 5.

[0043] Figure 8 Cyclic voltammetry curves of the CuNb2O6@C / / PFC lithium-ion capacitor device prepared in Example 5 at different scan rates.

[0044] Figure 9 The constant current charge-discharge curves of the CuNb2O6@C / / PFC lithium-ion capacitor device prepared in Example 5 under different current densities are shown.

[0045] Figure 10The rate performance diagram shows the CuNb2O6@C / / PFC lithium-ion capacitor device prepared in Example 5. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] The preparation of carbon nanoflowers includes the following steps: Coconut shells are pulverized and calcined at 650 °C for 3 hours in a nitrogen atmosphere to obtain coconut shell-derived carbon black powder. 5 g of coconut shell-derived carbon black powder is thoroughly mixed with 10.5 g of potassium carbonate and 9.5 g of sodium carbonate, and then transferred to an activation furnace. Under a N2 atmosphere, the temperature is increased to 900 °C at 10 °C / min and held for 5 hours. After natural cooling, the mixture is stirred in a 10 wt% HCl solution for 5 hours, washed with water until neutral, and then vacuum dried at 80 °C to obtain three-dimensional porous flower-like carbon. The carbon nanoflowers used in the following examples were all prepared using the above method.

[0048] Example 1

[0049] A three-dimensional flower-like carbon-supported CuNb2O6 material, prepared by the following method:

[0050] (1) Weigh 0.1 g of copper oxide and 0.2 g of niobium oxide and dissolve them in 20 mL of deionized water and stir for 15 min to obtain a well mixed solution.

[0051] (2) Dissolve 0.05 g of hexadecyltrimethylammonium bromide in the solution obtained in step (1) and stir for 20 min to obtain a clear solution.

[0052] (3) Add 0.1 g of carbon nanoflowers to the clear solution obtained in step three, disperse by ultrasonication for 20 min, and stir for 20 min in a water bath at 80 ℃ to obtain a mixed suspension.

[0053] (4) Dry in a forced-air drying oven at 80 °C for 12 h to obtain a black powder, and grind it evenly.

[0054] (5) Place the mixed material in a tube furnace under an argon atmosphere, with a reaction temperature of 900 °C and a reaction time of 3 h, wherein the heating rate is 5 °C / min, and after activation, allow it to cool naturally to room temperature.

[0055] (6) The activated material was washed with 1 mol / L HCl solution and deionized water until the solution was neutral. Finally, it was freeze-dried in a freeze dryer for 12 h to obtain a three-dimensional flower-like carbon-supported CuNb2O6 material, named CuNb2O6@C-3.

[0056] Electrode fabrication: The prepared CuNb2O6@C-3, acetylene black, and polyvinylidene fluoride binder were mixed in a mass ratio of 8:1:1 and stirred in a degassing machine for 1.5 h. Coated using copper foil as the current collector on a small coating machine, the mixture was then dried overnight in a 120°C vacuum drying oven. The electrodes were cut into 12 mm round discs with a loading of 1.5 mg / cm³. 2 .

[0057] The electrochemical performance of the obtained electrodes was tested using coin cells of lithium-ion half-cells, with lithium hexafluorophosphate as the electrolyte, lithium foil as the counter electrode, and a polyethylene microporous membrane as the separator. Constant current charge-discharge cycle testing and rate performance testing were conducted using a Blue Electric testing system. The constant current charge-discharge performance test settings included a voltage range of 0.8 V to 3 V and a current density of 0.1 C. The rate performance test was conducted within the range of 0.1 C to 50 C.

[0058] The three-dimensional flower-like carbon-supported CuNb2O6 material obtained through Example 1 is shown in the attached figure, wherein... Figure 1 Scanning electron microscopy revealed that the prepared material grew in bulk form on a three-dimensional carbon nanoflower substrate.

[0059] Example 2

[0060] A three-dimensional flower-like carbon-supported CuNb2O6 material, prepared by the following method:

[0061] (1) Weigh 0.0666 g of copper oxide and 0.1333 g of niobium oxide and dissolve them in 20 mL of deionized water and stir for 15 min to obtain a well mixed solution.

[0062] (2) Dissolve 0.05 g of hexadecyltrimethylammonium bromide in the solution obtained in step (1) and stir for 20 min to obtain a clear solution.

[0063] (3) Add 0.1 g of carbon nanoflowers to the clear solution obtained in step three, disperse by ultrasonication for 20 min, and stir for 20 min in a water bath at 80 ℃ to obtain a mixed suspension.

[0064] (4) Dry in a forced-air drying oven at 80 °C for 12 h to obtain a black powder, and grind it evenly.

[0065] (5) Place the mixed material in a tube furnace under an argon atmosphere, with a reaction temperature of 900 °C and a reaction time of 3 h, wherein the heating rate is 5 °C / min, and after activation, allow it to cool naturally to room temperature.

[0066] (6) The activated material was washed with 1 mol / L HCl solution and deionized water until the solution was neutral. Finally, it was freeze-dried in a freeze dryer for 12 h to obtain a three-dimensional flower-like carbon-supported CuNb2O6 material, named CuNb2O6@C-2.

[0067] Electrode fabrication: The prepared CuNb2O6@C-2, acetylene black, and polyvinylidene fluoride binder were mixed in a mass ratio of 8:1:1 and stirred in a degassing machine for 1.5 h. Coated using copper foil as the current collector on a small coating machine, the mixture was then dried overnight in a vacuum drying oven at 120℃. The electrodes were cut into 12 mm round discs with a loading of 1.6 mg / cm³. 2 .

[0068] The electrochemical performance of the obtained electrodes was tested using coin cells of lithium-ion half-cells, with lithium hexafluorophosphate as the electrolyte, lithium foil as the counter electrode, and a polyethylene microporous membrane as the separator. Constant current charge-discharge cycle testing and rate performance testing were conducted using a Blue Electric testing system. The constant current charge-discharge performance test settings included a voltage range of 0.8 V to 3 V and a current density of 0.1 C. The rate performance test was conducted within the range of 0.1 C to 50 C.

[0069] Example 3

[0070] A three-dimensional flower-like carbon-supported CuNb2O6 material, prepared by the following method:

[0071] (1) Weigh 0.1333 g of copper oxide and 0.2666 g of niobium oxide and dissolve them in 20 mL of deionized water and stir for 15 min to obtain a well mixed solution.

[0072] (2) Dissolve 0.05 g of hexadecyltrimethylammonium bromide in the solution obtained in step (1) and stir for 20 min to obtain a clear solution.

[0073] (3) Add 0.1 g of carbon nanoflowers to the clear solution obtained in step three, disperse by ultrasonication for 20 min, and stir for 20 min in a water bath at 80 ℃ to obtain a mixed suspension.

[0074] (4) Dry in a forced-air drying oven at 80 °C for 12 h to obtain a black powder, and grind it evenly.

[0075] (5) Place the mixed material in a tube furnace under an argon atmosphere, with a reaction temperature of 900 °C and a reaction time of 3 h, wherein the heating rate is 5 °C / min, and after activation, allow it to cool naturally to room temperature.

[0076] (6) The activated material was washed with 1 mol / L HCl solution and deionized water until the solution was neutral. Finally, it was freeze-dried in a freeze dryer for 12 h to obtain a three-dimensional flower-like carbon-supported CuNb2O6 material, named CuNb2O6@C-4.

[0077] Electrode fabrication: The prepared CuNb2O6@C-4, acetylene black, and polyvinylidene fluoride binder were mixed in a mass ratio of 8:1:1 and stirred in a degassing machine for 1.5 h. Coated using copper foil as the current collector on a small coating machine, the mixture was then dried overnight in a 120°C vacuum drying oven. The electrodes were cut into 12 mm round discs with a loading of 1.5 mg / cm³. 2 .

[0078] The electrochemical performance of the obtained electrodes was tested using coin cells of lithium-ion half-cells, with lithium hexafluorophosphate as the electrolyte, lithium foil as the counter electrode, and a polyethylene microporous membrane as the separator. Constant current charge-discharge cycle testing and rate performance testing were conducted using a Blue Electric testing system. The constant current charge-discharge performance test settings included a voltage range of 0.8 V to 3 V and a current density of 0.1 C. The rate performance test was conducted within the range of 0.1 C to 50 C.

[0079] Comparative Example 1

[0080] A method for preparing CuNb2O6 material, differing in that carbon nanoflowers are not added in the steps. The preparation method includes:

[0081] (1) Weigh 0.1 g of copper oxide and 0.2 g of niobium oxide and dissolve them in 20 mL of deionized water and stir for 15 min to obtain a well mixed solution.

[0082] (2) Dissolve 0.05 g of hexadecyltrimethylammonium bromide in the solution obtained in step (1) and stir for 20 min to obtain a clear solution.

[0083] (3) Dry in a forced-air drying oven at 80 ℃ for 12 h to obtain a powder, and grind it evenly.

[0084] (4) Place the mixed material in a tube furnace under an argon atmosphere, with a reaction temperature of 900 ℃ and a reaction time of 3 h, wherein the heating rate is 5 ℃ / min, and after activation, allow it to cool naturally to room temperature.

[0085] (5) The activated material was washed with 1 mol / L HCl solution and deionized water until the solution was neutral. Finally, it was freeze-dried in a freeze dryer for 12 h to obtain CuNb2O6 material, which was named CuNb2O6.

[0086] Electrode fabrication: The prepared CuNb2O6 material, acetylene black, and polyvinylidene fluoride binder were mixed in a mass ratio of 8:1:1 and stirred in a degassing machine for 1.5 h. Coated using copper foil as the current collector, the mixture was applied on a small coating machine and dried overnight in a 120°C vacuum drying oven. The electrodes were then cut into 12 mm round discs with a loading of 1.5 mg / cm³. 2 .

[0087] The electrochemical performance of the obtained electrodes was tested using coin cells of lithium-ion half-cells, with lithium hexafluorophosphate as the electrolyte, lithium foil as the counter electrode, and a polyethylene microporous membrane as the separator. Constant current charge-discharge cycle testing and rate performance testing were conducted using a Blue Electric testing system. The constant current charge-discharge performance test settings included a voltage range of 0.8 V to 3 V and a current density of 0.1 C. The rate performance test was conducted within the range of 0.1 C to 50 C.

[0088] Comparative Example 2

[0089] A carbon-supported CuNb2O6 material, prepared by a method comprising:

[0090] (1) Weigh 0.1 g of copper oxide and 0.2 g of niobium oxide and dissolve them in 20 mL of deionized water and stir for 15 min to obtain a well mixed solution.

[0091] (2) Dissolve 0.05 g of hexadecyltrimethylammonium bromide in the solution obtained in step (1) and stir for 20 min to obtain a clear solution.

[0092] (3) Add 0.1 g of coconut shell-derived carbon black powder to the clear solution obtained in step three, disperse it ultrasonically for 20 min, and stir it in a water bath at 80 ℃ for 20 min to obtain a mixed suspension.

[0093] (4) Dry in a forced-air drying oven at 80℃ for 12 h to obtain a black powder, and grind it evenly.

[0094] (5) Place the mixture in a tube furnace under an argon atmosphere, and the reaction temperature is 900°C. o C, reaction time is 3 h, with a heating rate of 5 o C / min, after activation, allow to cool naturally to room temperature.

[0095] (6) The activated material was washed with 1 mol / L HCl solution and deionized water until the solution was neutral. Finally, it was freeze-dried in a freeze dryer for 12 h to obtain carbon-supported CuNb2O6 material.

[0096] Electrode fabrication: The prepared carbon-supported CuNb2O6 material, acetylene black, and polyvinylidene fluoride binder were mixed in a mass ratio of 8:1:1 and stirred in a degassing machine for 1.5 h. Coated using copper foil as the current collector on a small coating machine, the mixture was then dried overnight in a 120°C vacuum drying oven. The electrodes were cut into 12 mm round discs with a loading of 1.5 mg / cm³. 2 .

[0097] The electrochemical performance of the obtained electrodes was tested using coin cells of lithium-ion half-cells, with lithium hexafluorophosphate as the electrolyte, lithium foil as the counter electrode, and a polyethylene microporous membrane as the separator. Constant current charge-discharge cycle testing and rate performance testing were conducted using a Blue Electric testing system. The constant current charge-discharge performance test settings included a voltage range of 0.8 V to 3 V and a current density of 0.1 C. The rate performance test was conducted within the range of 0.1 C to 50 C.

[0098] Figure 2 The X-ray diffraction patterns of the materials prepared in Examples 1-3 and Comparative Example 1 clearly show that CuNb2O6 is present in all the prepared materials.

[0099] Figure 3 The figures show the constant current charge-discharge curves of lithium-ion half-cells obtained from the materials prepared in Examples 1-3 and Comparative Example 1. At a charging rate of 0.1C, the material exhibits the following discharge specific capacities: CuNb2O6@C-2 (313.1 mAh g⁻¹). -1 CuNb2O6@C-3 (407.3 mAh g) -1 CuNb2O6@C-4 (349.3 mAh g) -1 CuNb2O6 (219.3 mAh g) -1 It can be seen that the materials obtained in Examples 1-3 are significantly better than those in Comparative Example 1, and there is a charge-discharge plateau at 1.75 V.

[0100] Figure 4 The graph shows the rate performance of lithium-ion half-cells obtained from the materials prepared in Examples 1-3 and Comparative Example 1. At 50C, the material from Example 1 still has a rate performance of 110.8 mAh g⁻¹. -1 The specific capacity of the sample represents a significant improvement in charge and discharge rates compared to CuNb2O6 in Comparative Example 1.

[0101] Figure 5The graph shows the cycling performance of lithium-ion half-cells prepared from the materials in Examples 1-3 and Comparative Example 1 at 0.5C. At 0.5C, Example 1 still exhibits significantly higher performance after 200 cycles compared to the others, maintaining a capacity of 324.9 mAh g⁻¹. -1 Specific capacity.

[0102] Figure 6 The graph shows the cycle performance of lithium-ion half-cells prepared from the materials in Examples 1-3 and Comparative Example 1 at 10C. At 10C, the material in Example 1 retains 95.1% of its capacitance after 1000 charge-discharge cycles, which is higher than that of CuNb2O6@C-2 (92.0%), CuNb2O6@C-4 (80.1%), and CuNb2O6 (71.3%). It also outperforms Comparative Example 1 in terms of specific capacity.

[0103] Analysis of the three-dimensional flower-like carbon-supported CuNb2O6 materials obtained through the above embodiments shows that, when the total mass of copper oxide and niobium oxide is 0.4, the overall performance of Example 1 is superior to that of the other embodiments. The electrochemical data of the three-dimensional flower-like carbon-supported CuNb2O6 materials obtained in Examples 1-3 and the comparative CuNb2O6 materials are shown in Table 1.

[0104] Table 1

[0105]

[0106] As shown in Table 1, the preparation method of the three-dimensional flower-shaped carbon-supported CuNb2O6 material provided by this invention can achieve high specific capacity, fast charge-discharge rate, and a capacity retention rate of 95.1% after 1000 cycles at 10C. The three-dimensional flower-shaped carbon-supported CuNb2O6 material obtained using the scheme in Example 1 has the highest specific capacity product and high rate cycling performance, thus verifying its potential as an electrode material for assembling lithium-ion capacitors.

[0107] Example 5

[0108] A lithium-ion capacitor device, the device comprising:

[0109] A button-type lithium-ion capacitor device was assembled using an RS2023 battery case, consisting of a negative electrode, a polyethylene microporous membrane, a positive electrode, and a lithium hexafluorophosphate electrolyte.

[0110] (1) The negative electrode is the electrode sheet prepared in Example 1.

[0111] (2) The positive electrode, three-dimensional carbon nanoflowers, acetylene black, and polyvinylidene fluoride binder are mixed in a mass ratio of 8:1:1, stirred in a degassing machine for 1.5 h, coated on a small coating machine using aluminum foil as the current collector, and dried overnight in a vacuum drying oven at 120 ℃. It is then cut into 12 mm round discs with a loading of 2 mg / cm³. 2 .

[0112] The obtained lithium-ion capacitors were subjected to impedance testing, cyclic voltammetry curve analysis, and constant current charge-discharge testing on a Chenhua CHI760E electrochemical workstation. The cyclic voltammetry test settings included a voltage range of 1 V to 3.5 V and a scan rate of 10–100 mV / s. -1 Impedance test settings: frequency range 100 kHz - 0.01 Hz, voltage is the initial open-circuit voltage; constant current charge / discharge performance test settings: voltage range 1 V to 3.5 V, current density 0.5 to 8 A g. -1 .

[0113] Figure 7 The image shows the impedance of the lithium-ion capacitor prepared in Example 5. Its X-axis intercept is close to the origin, and there is a distinct small semicircle in the high-frequency region. The straight line in the low-frequency region is almost parallel to the y-axis, which is close to an ideal capacitor device.

[0114] Figure 8 The lithium-ion capacitor prepared in Example 5 exhibits performance in the range of 10-100 mV / s. -1 Cyclic voltammetry curves under the following conditions: 10-100 mV / s. -1 The presence of this pair of redox peaks at all scan rates proves that the redox reaction is occurring in the device during charging and discharging.

[0115] Figure 9 The lithium-ion capacitor prepared in Example 5 was in the range of 0.5-8 A g. -1 The constant current charge-discharge curves are shown. The charging and discharging curves exhibit near-symmetry, demonstrating the capacitor's excellent rate performance. The device operates at 0.5 A g. -1 The specific capacitance at that time was 302 F g -1 .

[0116] Figure 10 The lithium-ion capacitor prepared in Example 5 was in the range of 0.5-8 A g. -1 The rate curve derived from the constant current charge-discharge curve under these conditions. At 8 A g -1 There are still 97 F g below -1 Specific capacitance,

[0117] The above provides a detailed description of the preparation method of a three-dimensional flower-shaped carbon-supported CuNb2O6 material provided by the present invention. By introducing a three-dimensional flower-shaped carbon network, the present invention achieves improvements in specific capacity, cycle performance, and fast charge-discharge performance.

[0118] Example 6

[0119] A three-dimensional flower-like carbon-supported CuNb2O6 material, prepared by the following method:

[0120] (1) Weigh 0.1 g of copper oxide and 0.3 g of niobium oxalate and dissolve them in 20 mL of deionized water and stir for 15 min to obtain a well mixed solution.

[0121] (2) Dissolve 0.01 g of hexadecyltrimethylammonium bromide in the solution obtained in step (1) and stir for 20 min to obtain a clear solution.

[0122] (3) Add 0.2 g of carbon nanoflowers to the clear solution obtained in step three, disperse by ultrasonication for 20 min, and stir for 30 min in a water bath at 60 ℃ to obtain a mixed suspension.

[0123] (4) Dry in a forced-air drying oven at 80 °C for 12 h to obtain a black powder, and grind it evenly.

[0124] (5) Place the mixed material in a tube furnace under an argon atmosphere, with a reaction temperature of 800 °C and a reaction time of 5 h, wherein the heating rate is 5 °C / min, and after activation, allow it to cool naturally to room temperature.

[0125] (6) The activated material was washed with 1 mol / L HCl solution and deionized water until the solution was neutral. Finally, it was freeze-dried in a freeze dryer for 12 h to obtain three-dimensional flower-like carbon-supported CuNb2O6 material.

[0126] Example 7

[0127] A three-dimensional flower-like carbon-supported CuNb2O6 material, prepared by the following method:

[0128] (1) Weigh 0.1 g of copper chloride and 0.1 g of niobium oxalate and dissolve them in 10 mL of deionized water and stir for 15 min to obtain a well mixed solution.

[0129] (2) Dissolve 0.1 g of sodium dodecyl sulfate in the solution obtained in step (1) and stir for 20 min to obtain a clear solution.

[0130] (3) Add 0.05 g of carbon nanoflowers to the clear solution obtained in step three, disperse ultrasonically for 20 min, and stir for 10 min in a water bath at 70°C to obtain a mixed suspension.

[0131] (4) Dry in a forced-air drying oven at 80 °C for 12 h to obtain a black powder, and grind it evenly.

[0132] (5) Place the mixed material in a tube furnace under an argon atmosphere, with a reaction temperature of 850 °C and a reaction time of 1 h, wherein the heating rate is 5 °C / min, and after activation, allow it to cool naturally to room temperature.

[0133] (6) The activated material was washed with 1 mol / L HCl solution and deionized water until the solution was neutral. Finally, it was freeze-dried in a freeze dryer for 12 h to obtain three-dimensional flower-like carbon-supported CuNb2O6 material.

[0134] Example 8

[0135] A three-dimensional flower-like carbon-supported CuNb2O6 material, prepared by the following method:

[0136] (1) Weigh 0.1 g of copper acetate and 0.3 g of niobium oxalate and dissolve them in a mixed solvent consisting of 10 mL of deionized water and 5 mL of ethanol. Stir for 15 min to obtain a well mixed solution.

[0137] (2) Dissolve 0.05 g of dodecyltrimethylammonium bromide in the solution obtained in step (1) and stir for 20 min to obtain a clear solution.

[0138] (3) Add 0.1 g of carbon nanoflowers to the clear solution obtained in step three, disperse by ultrasonication for 20 min, and stir for 10 min in a water bath at 70 ℃ to obtain a mixed suspension.

[0139] (4) Dry in a forced-air drying oven at 80 °C for 12 h to obtain a black powder, and grind it evenly.

[0140] (5) Place the mixed material in a tube furnace under an argon atmosphere, with a reaction temperature of 850 °C and a reaction time of 1 h, wherein the heating rate is 5 °C / min, and after activation, allow it to cool naturally to room temperature.

[0141] (6) The activated material was washed with 1 mol / L HCl solution and deionized water until the solution was neutral. Finally, it was freeze-dried in a freeze dryer for 12 h to obtain three-dimensional flower-like carbon-supported CuNb2O6 material.

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a three-dimensional flower-like carbon-supported CuNb2O6 material, characterized in that, Includes the following steps: (1) Dissolve the niobium source, copper source and surfactant in a solvent, stir and mix to obtain a precursor solution; (2) Carbon nanoflowers were added to the precursor solution for reaction. After the reaction was completed, the solvent was evaporated to obtain CuNb2O6 precursor. (3) The CuNb2O6 precursor was calcined, cooled, washed, and freeze-dried to obtain a three-dimensional flower-shaped carbon-supported CuNb2O6 material.

2. The method for preparing the three-dimensional flower-like carbon-supported CuNb2O6 material according to claim 1, characterized in that, The niobium source is niobium oxide and / or niobium oxalate; the surfactant is one or more of hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, or dodecyltrimethylammonium bromide; the copper source is one or more of copper oxide, copper nitrate, copper chloride, copper sulfate, or copper acetate; and the solvent is deionized water or a mixture of deionized water and alcohol.

3. The method for preparing the three-dimensional flower-like carbon-supported CuNb2O6 material according to claim 2, characterized in that, The mass ratio of the copper source, niobium source, and surfactant is 1:1-3:0.1-1; the concentration of the niobium source in the precursor solution is 0.1-5 wt%.

4. The method for preparing the three-dimensional flower-like carbon-supported CuNb2O6 material according to claim 3, characterized in that, The ratio of the amount of carbon nanoflowers added in step (2) to the mass ratio of the copper source in step (1) is 1:0.5-2.

5. The method for preparing the three-dimensional flower-like carbon-supported CuNb2O6 material according to any one of claims 1-4, characterized in that, The carbon nanoflowers are prepared by mixing a carbon source and a pore-forming agent in a mass ratio of 1:2-5 and then activating and calcining them at 800-1000℃ for 1-10 hours.

6. The method for preparing the three-dimensional flower-like carbon-supported CuNb2O6 material according to claim 5, characterized in that, The carbon source is a biomass carbon source; the biomass carbon source is coconut shell charcoal, bamboo charcoal, or wood chip charcoal; the pore-forming agent is a carbonate; the carbonate is one or more of potassium carbonate, sodium carbonate, calcium carbonate, sodium bicarbonate, or potassium bicarbonate.

7. The method for preparing the three-dimensional flower-like carbon-supported CuNb2O6 material according to claim 1, characterized in that, The reaction temperature in step (2) is 60-80 ℃ and the time is 10-30 min.

8. The method for preparing the three-dimensional flower-like carbon-supported CuNb2O6 material according to claim 7, characterized in that, The calcination process is carried out in an inert gas atmosphere at a temperature of 800-900 ℃ for 1-5 h.

9. A three-dimensional flower-like carbon-supported CuNb2O6 material prepared by the method of any one of claims 1-8.

10. The application of the three-dimensional flower-like carbon-supported CuNb2O6 material according to claim 9 in an electrode, characterized in that, An electrode is prepared by mixing a three-dimensional flower-shaped carbon-supported CuNb2O6 material, a conductive agent, and a binder, and then coating the mixture onto a current collector.

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