A method for preparing interface-enhanced niobium pentoxide / porous graphene and its energy storage application.
By preparing an interface-enhanced niobium pentoxide/porous graphene composite material, the conductivity and transmission efficiency problems of niobium pentoxide in the field of energy storage were solved, improving the rate performance and cycle stability of sodium-ion batteries, making it suitable for large-scale production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEFEI UNIV OF TECH
- Filing Date
- 2023-11-17
- Publication Date
- 2026-05-26
AI Technical Summary
The low intrinsic ion mobility and conductivity of niobium pentoxide severely affect its application in the energy storage field, and sodium-ion batteries have poor rate performance and cycle stability.
By incorporating porous graphene oxide into the solvothermal synthesis of niobium pentoxide precursor, an interface-enhanced niobium pentoxide/porous graphene composite material is formed. The porous graphene oxide serves as a nucleation substrate to promote the in-situ growth of niobium pentoxide, and stable CO-Nb interfacial chemical bonds are formed under high-temperature annealing, thereby enhancing the stability of electron transfer and sodium ion insertion/extraction processes.
The electronic conductivity and sodium ion transport efficiency of niobium pentoxide were improved, the energy storage performance of the anode material was enhanced, the volume expansion during the charging and discharging process was alleviated, and excellent rate performance and structural stability were achieved.
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Figure CN117585720B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of functional materials preparation, specifically relating to a method for preparing interface-enhanced niobium pentoxide / porous graphene and its energy storage application. Background Technology
[0002] In recent years, with the development of renewable energy technologies and electric vehicles, the demand for energy storage systems has grown rapidly. However, the uneven distribution of lithium hinders the large-scale utilization of lithium-ion batteries (LIBs). Therefore, alternative energy storage technologies are under development to meet future energy demands. Abundant sodium resources make sodium-ion batteries (SIBs) a promising alternative to lithium-ion batteries. However, because sodium ions are larger than lithium ions, SIBs suffer from poor rate performance and cycle stability. Therefore, researchers are searching for alternative electrode materials with high capacity. Niobium pentoxide (Nb₂O₅) has attracted widespread research attention due to its layered structure. The layered structure of niobium pentoxide facilitates the insertion and extraction of sodium ions during charge and discharge; moreover, niobium pentoxide exhibits superior pseudocapacitive performance in energy storage applications, ensuring excellent energy storage capacity. However, niobium pentoxide has low intrinsic ion mobility and conductivity, which severely affects its rate performance and hinders its practical application in the energy storage field. Designing suitable nanostructures to shorten the Na₂O₅ layer is a promising approach. + Diffusion pathways and compositing with suitable conductive carbon materials to improve their electronic conductivity are strategies for improving the electrochemical kinetics of niobium pentoxide. Summary of the Invention
[0003] Based on the problems existing in the prior art, the purpose of this invention is to provide a method for preparing interface-enhanced niobium pentoxide / porous graphene and its energy storage application.
[0004] To achieve its objectives, the present invention employs the following technical solution:
[0005] A method for preparing interface-reinforced niobium pentoxide / porous graphene is characterized by the addition of porous graphene oxide during the solvothermal synthesis of the niobium pentoxide precursor to obtain a composite precursor of niobium pentoxide and porous graphene oxide. The precursor is then annealed under a protective atmosphere to obtain the interface-reinforced niobium pentoxide / porous graphene composite material. The specific steps include:
[0006] Step 1: Prepare porous graphene oxide aqueous solution
[0007] Graphene oxide was prepared at a concentration of 0.1–1 mg / mL. -1 The concentration of the solution was ultrasonically dispersed in deionized water, and then placed in an oil bath at 90–120°C. H2O2 solution was added, and the oil bath was treated for 0.5–4 hours to obtain a porous graphene oxide aqueous solution.
[0008] Step 2: Preparation of niobium pentoxide / porous graphene oxide precursor by solvothermal method
[0009] Weigh 0.5–1.8 mmol of niobium salt and 1.5–10 mmol of hexamethylenetetramine and dissolve them in a mixed solution of 45–120 mL of porous graphene oxide aqueous solution and ethylene glycol. After stirring evenly, carry out a solvothermal reaction, then centrifuge, wash, dry, and collect the powder product to obtain niobium pentoxide / porous graphene oxide precursor.
[0010] Step 3: Annealing under an inert atmosphere to prepare interface-reinforced niobium pentoxide / porous graphene composite material
[0011] Weigh 50–200 mg of niobium pentoxide / porous graphene oxide precursor and place it in a tube furnace. Anneal it under an inert atmosphere and then cool it to room temperature in the furnace to obtain an interface-reinforced niobium pentoxide / porous graphene composite material.
[0012] Preferably, in step 1, the volume concentration of the H2O2 solution is 30%, and its volume ratio with deionized water is 1:5 to 10.
[0013] Preferably, in step 2, the temperature of the solvothermal reaction is 100–200°C and the holding time is 12–48 h.
[0014] Preferably, in step 2, the volume ratio of the porous graphene oxide aqueous solution to ethylene glycol is 1:0.1 to 1.
[0015] Preferably, in step 3, the heating rate of the annealing treatment is 1–10 °C / min. -1 The temperature is 500-900℃ and the holding time is 90-360 minutes.
[0016] Preferably, in step 3, the inert atmosphere is argon, nitrogen, or a mixture of hydrogen and argon.
[0017] The interface-reinforced niobium pentoxide / porous graphene composite material prepared by this invention can be used in the field of electrochemical energy storage, such as as a negative electrode material for batteries, exhibiting excellent rate performance.
[0018] Compared with existing technologies, the beneficial effects of this invention are as follows:
[0019] 1. Niobium pentoxide is a typical intercalated pseudocapacitor material, characterized by high specific capacitance and small volume change. This invention combines niobium pentoxide with porous graphene oxide. During solvothermal processing, the porous graphene oxide, with its oxygen-containing functional groups, serves as a nucleation substrate, promoting in-situ growth of niobium pentoxide on its surface and forming stable CO-Nb interfacial chemical bonds. This not only facilitates electron transfer but also helps maintain the stability of the electrode structure during sodium ion insertion / extraction. Furthermore, the abundant oxygen-containing groups inhibit the nucleation and growth of niobium pentoxide, resulting in small-sized nanosheets encapsulated in graphene, effectively mitigating volume expansion during charge and discharge.
[0020] 2. Compared with directly combining niobium pentoxide with graphene, the porous graphene design of this invention enables longitudinal transport of ions in the middle of the sheets, effectively solving the problems of two-dimensional sheet agglomeration and high resistance to longitudinal ion transport, and further improving the energy storage performance of the anode material.
[0021] 3. The preparation method of the present invention has universal applicability and can be applied to other metal oxides, thereby improving the conductivity and structural stability of different metal oxides.
[0022] 4. The preparation method of the present invention is simple, has a short preparation time, low cost, and is easy to control, and can be applied to large-scale production. Attached Figure Description
[0023] Figure 1 FESEM image of the niobium pentoxide precursor prepared in Example 1;
[0024] Figure 2 FESEM image of niobium pentoxide prepared in Example 1;
[0025] Figure 3 FESEM image of the niobium pentoxide / graphene oxide precursor prepared in Example 2;
[0026] Figure 4 FESEM image of the niobium pentoxide / graphene composite material prepared in Example 2;
[0027] Figure 5 FESEM image of the niobium pentoxide / porous graphene oxide precursor prepared in Example 3;
[0028] Figure 6 FESEM image of the interface-reinforced niobium pentoxide / porous graphene composite material prepared in Example 3;
[0029] Figure 7The XRD patterns of niobium pentoxide, niobium pentoxide / graphene composite material, and interface-reinforced niobium pentoxide / porous graphene composite material prepared in Examples 1, 2, and 3 are shown.
[0030] Figure 8 Nitrogen adsorption-desorption curves of niobium pentoxide, niobium pentoxide / graphene composite material, and interface-reinforced niobium pentoxide / porous graphene composite material prepared in Examples 1, 2, and 3;
[0031] Figure 9 Button batteries assembled from niobium pentoxide, niobium pentoxide / graphene composite material, and interface-reinforced niobium pentoxide / porous graphene composite material prepared in Examples 1, 2, and 3 were tested at different current densities (50–10000 mAg). -1 The scaling factor curve. Detailed Implementation
[0032] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to examples. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0033] Example 1
[0034] In this embodiment, niobium pentoxide is prepared according to the following steps:
[0035] Step 1: Solvothermal preparation of niobium pentoxide precursor
[0036] 1.8 mmol of niobium pentachloride and 7.2 mmol of hexamethylenetetramine were weighed and dissolved in 90 mL of a 1:1 mixture of water and ethylene glycol. After stirring and dissolving, a solvothermal reaction was carried out at 200 °C for 12 h. After the reaction, the product was centrifuged, washed, dried, and collected as a powder, which is the niobium pentoxide precursor. Its FESEM is shown in Figure 1. Figure 1 As shown.
[0037] Step 2: High-temperature annealing treatment to prepare niobium pentoxide
[0038] 100 mg of the prepared niobium pentoxide precursor was weighed and placed in a tube furnace, and subjected to high-temperature annealing under an argon protective atmosphere. The annealing temperature was 700 °C, and the heating rate was 2 °C / min. -1 The holding time was 2 hours. Then, it was cooled to room temperature in the furnace to obtain niobium pentoxide material, whose FESEM image was as follows: Figure 2 As shown, the XRD pattern is as follows Figure 7 As shown.
[0039] As shown in the FESEM images, the niobium pentoxide precursor synthesized by the solvothermal method is a nanoflower structure assembled from ultrathin nanosheets, exhibiting a uniform morphology. After high-temperature annealing, the nanosheets break down and thicken, but the morphology is still maintained. In the XRD pattern, the diffraction peaks of niobium pentoxide are strong and sharp, corresponding to the standard spectrum.
[0040] Example 2
[0041] In this embodiment, niobium pentoxide / graphene composite material was prepared according to the following steps:
[0042] Step 1: Solvothermal preparation of niobium pentoxide / graphene oxide precursor
[0043] 1.8 mmol of niobium pentachloride, 7.2 mmol of hexamethylenetetramine, and 45 mg of graphene oxide were weighed and dissolved in 90 mL of a 1:1 volume ratio of water and ethylene glycol. After stirring and dissolving, a solvothermal reaction was carried out at 200 °C for 12 h. After the reaction, the product was centrifuged, washed, dried, and collected as a powder, which is the niobium pentoxide / graphene oxide precursor. Its FESEM is shown in the figure. Figure 3 As shown.
[0044] Step 2: High-temperature annealing treatment to prepare niobium pentoxide / graphene composite material
[0045] 100 mg of the prepared niobium pentoxide / graphene oxide precursor was weighed and placed in a tube furnace, and subjected to high-temperature annealing under an argon protective atmosphere. The annealing temperature was 700 °C, and the heating rate was 2 °C / min. -1 The holding time was 2 hours. Then, it was cooled to room temperature in the furnace to obtain the niobium pentoxide / graphene composite material, whose FESEM image is shown below. Figure 4 As shown, the XRD pattern is as follows Figure 7 As shown.
[0046] As shown in the FESEM images, niobium pentoxide grows in situ on the surface of graphene oxide rich in oxygen-containing functional groups, forming a niobium pentoxide / graphene oxide composite material. After high-temperature annealing, pores appear in the sheet-like structure, but the morphology is still maintained. In the XRD pattern, the phase of the niobium pentoxide-graphene composite remains unchanged, still maintaining the highly crystalline niobium pentoxide phase.
[0047] Example 3
[0048] In this embodiment, an interface-reinforced niobium pentoxide / porous graphene composite material was prepared according to the following steps:
[0049] Step 1: Prepare porous graphene oxide aqueous solution
[0050] Weigh an appropriate amount of graphene oxide and ultrasonically disperse it in a certain volume of deionized water, so that the graphene oxide concentration is 1 mg / ml. -1 The solution was placed in an oil bath at 120°C, and a 30% hydrogen peroxide solution (with a volume ratio of 1:9 to deionized water) was added. The solution was then treated in the oil bath for 2 hours to obtain a porous graphene oxide aqueous solution.
[0051] Step 2: Solvothermal preparation of niobium pentoxide / porous graphene oxide precursor
[0052] 1.8 mmol of niobium pentachloride and 7.2 mmol of hexamethylenetetramine were dissolved in 90 mL of a mixed solution of porous graphene oxide aqueous solution and ethylene glycol in a 1:1 volume ratio. After stirring and dissolving, a solvothermal reaction was carried out at 200 °C for 12 h. After the reaction, the product was centrifuged, washed, dried, and collected as a powder, which is the niobium pentoxide / porous graphene oxide precursor. Its FESEM is shown in the figure. Figure 5 As shown.
[0053] Step 3: High-temperature annealing treatment to prepare interface-reinforced niobium pentoxide / porous graphene composite material
[0054] 100 mg of the prepared niobium pentoxide / porous graphene oxide precursor was weighed and placed in a tube furnace, and subjected to high-temperature annealing under an argon protective atmosphere. The annealing temperature was 700 °C, and the heating rate was 2 °C / min. -1 The holding time was 2 hours. Then, it was cooled to room temperature in the furnace to obtain the niobium pentoxide / porous graphene composite material, whose FESEM image is shown below. Figure 6 As shown, the XRD pattern is as follows Figure 7 As shown.
[0055] As shown in the FESEM images, after the porous graphene oxide is combined with niobium pentoxide, the morphology changes from a uniform, ultrathin nanoflower-like structure to smaller nanosheets. After annealing, a layer of porous graphene covers the surface of the niobium pentoxide, effectively mitigating volume expansion and maintaining structural stability. Figure 7 The XRD pattern shows that the phase is still niobium pentoxide.
[0056] Figure 8 The nitrogen adsorption-desorption curves are shown. The specific surface areas of niobium pentoxide, niobium pentoxide / graphene composite material, and interface-reinforced niobium pentoxide / porous graphene composite material obtained in Examples 1, 2, and 3 are 34.1 m², respectively. 2 g -1 113.6m 2 g -1 186.6m 2 g-1 .
[0057] Referring to the above embodiments, this invention investigated the microstructure and phase composition of porous graphene combined with niobium pentoxide. XRD characterization showed that Examples 1-3 all exhibited similar diffraction peaks, corresponding to the orthorhombic phase of niobium pentoxide (JCPDS No. 30-0873). To test the performance of the materials prepared in Examples 1, 2, and 3 as electrochemical energy storage materials, they were assembled into batteries and electrochemical tests were performed as follows: The materials synthesized in Examples 1, 2, and 3 were respectively mixed with acetylene black and polyvinylidene fluoride (PVDF) at a mass ratio of 8:1:1 to form slurries, which were then coated onto copper foil to form electrode sheets. The electrode sheets were prepared by dissolving ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1.0 mol / L solution (volume ratio 1:1). -1 Using NaPF6 as the electrolyte and a 2320 type polypropylene microporous membrane as the separator, a 2032 type button cell was assembled in a glove box. The results were tested using a LANDCT-2001A testing system at room temperature, within a voltage range of 0.01–3.0V, and at a capacitance of 50–10000 mAg. -1 Constant current charge-discharge tests were performed at a current density of [value missing].
[0058] Figure 9 The materials prepared in Examples 1, 2, and 3 were subjected to different current densities (50–10000 mAg). -1 The rate performance curves of the material prepared in Example 1 were obtained. The results show that the material at 50 mAg... -1 The discharge specific capacity at the specified current density is 84.43 mAh g. -1 At a current density of 2000 mAg -1 The capacity decays to 0; the material prepared in Example 2 decays to 0 at 50 mAg. -1 The discharge specific capacity at current density is 236.48 mAh g. -1 At 10000mAg -1 The discharge specific capacity at the given current density is 70.88 mAh g. -1 The material prepared in Example 3 was tested at 50 mAg. -1 The discharge specific capacity at current density is 287.98 mAh g. -1 At 10000mAg -1 The discharge specific capacity at the given current density is 89.08 mAh g. -1 Compared with Examples 1 and 2, the material prepared in Example 3 has superior rate performance and can be used as an ideal anode material for sodium-ion batteries.
[0059] The scope of protection of this invention is not limited to the above embodiments. Any variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of the inventive concept are included in this invention and are protected by the appended claims.
Claims
1. A method for preparing interface-enhanced niobium pentoxide / porous graphene, characterized in that: Porous graphene oxide was added during the solvothermal synthesis of niobium pentoxide precursor to obtain a composite precursor of niobium pentoxide and porous graphene oxide. Then, annealing was performed under a protective atmosphere to obtain an interface-reinforced niobium pentoxide / porous graphene composite material. The specific steps included are as follows: Step 1: Prepare porous graphene oxide aqueous solution Graphene oxide was prepared at a concentration of 0.1–1 mg / mL. -1 The concentration of the substance was ultrasonically dispersed in deionized water, and then placed in an oil bath at 90~120 ℃. H2O2 solution was added, and the oil bath was treated for 0.5~4 h to obtain a porous graphene oxide aqueous solution. Step 2: Preparation of niobium pentoxide / porous graphene oxide precursor by solvothermal method Weigh 0.5–1.8 mmol of niobium salt and 1.5–10 mmol of hexamethylenetetramine and dissolve them in a mixed solution of 45–120 mL of porous graphene oxide aqueous solution and ethylene glycol. After stirring evenly, carry out a solvothermal reaction at 100–200 °C for 12–48 h. Then centrifuge, wash, dry, and collect the powder product to obtain niobium pentoxide / porous graphene oxide precursor. Step 3: Annealing under an inert atmosphere to prepare interface-reinforced niobium pentoxide / porous graphene composite material Weigh 50-200 mg of niobium pentoxide / porous graphene oxide precursor and place it in a tube furnace for annealing under an inert atmosphere. The annealing process is carried out at a heating rate of 1-10 °C / min. -1 The temperature is 500~900 ºC, the holding time is 90~360 min, and then the furnace is cooled to room temperature to obtain the interface-reinforced niobium pentoxide / porous graphene composite material.
2. The method for preparing interface-enhanced niobium pentoxide / porous graphene according to claim 1, characterized in that: In step 1, the volume concentration of the H2O2 solution is 30%, and its volume ratio with deionized water is 1:5~10.
3. The method for preparing interface-enhanced niobium pentoxide / porous graphene according to claim 1, characterized in that: In step 2, the volume ratio of porous graphene oxide aqueous solution to ethylene glycol is 1:0.1~1.
4. The method for preparing interface-enhanced niobium pentoxide / porous graphene according to claim 1, characterized in that: In step 3, the inert atmosphere is argon, nitrogen, or a mixture of hydrogen and argon.
5. An interface-reinforced niobium pentoxide / porous graphene composite material prepared by the preparation method according to any one of claims 1 to 4.
6. The application of the interface-reinforced niobium pentoxide / porous graphene composite material as described in claim 5 as an electrochemical energy storage material.