V-Nb-Ti-Ox nanofiber as well as preparation method and application thereof
By preparing V-Nb-Ti-Ox nanofibers, the limitations of existing negative electrode materials in capacity density, cycle performance and rate performance are solved, and high capacity and long-term stability of lithium-ion batteries are achieved. In particular, the comprehensive performance of the material is improved through electrospinning technology and uniform attachment of oxides to carbon nanofibers.
Patent Information
- Application Number
- CN202510776977.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-11
- Publication Date
- 2025-09-19
AI Technical Summary
Existing negative electrode materials such as natural graphite, artificial graphite and hard carbon have reached their limits in terms of capacity density, cycle performance and rate performance, and the volume expansion problem of silicon-carbon negative electrode materials has not been effectively solved.
V-Nb-Ti-Ox nanofibers are prepared using electrospinning technology. By uniformly attaching vanadium oxide, niobium oxide and titanium oxide to carbon nanofibers, V-Nb-Ti-Ox nanofibers are formed, which improves the material's capacity density, cycle performance and rate performance, and alleviates volume expansion.
The high capacity, good rate performance and long-term cycle stability of the negative electrode material are achieved, and the electrochemical performance of the lithium-ion battery is improved through the combination of nanostructure and oxide.
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Figure BDA0005444628600000071
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of negative electrode materials, and in particular to a V-Nb-Ti-O x Nanofibers and their preparation methods and applications. Background Art
[0002] The current negative electrode materials mainly include natural graphite, artificial graphite, hard carbon, silicon-carbon composite materials, etc., but they all have certain limitations. It is imperative to improve the performance of existing negative electrode materials through modification or compounding.
[0003] Natural graphite has a flaky structure and a capacity close to the theoretical capacity of graphite, 372 mAh / g. However, its flake structure easily delaminates, resulting in poor cycling performance. Artificial graphite has a more stable structure than natural graphite, but its actual specific capacity is limited to 355-360 mAh / g. Graphite anode materials have reached near-limited capacity density. While extensive research has been conducted on improving rate performance through soft / hard carbon coating, their long-cycle performance has also been largely exploited to its limits, leaving the pure graphite anode material route essentially at a bottleneck. Hard carbon is primarily used in sodium-ion batteries, but its application prospects and processing performance are inferior to other anode materials. Silicon-carbon anode materials offer promising applications. While their specific capacity is high, their volume expansion has hindered their large-scale application. Therefore, new materials are needed to improve the performance of anode materials. Summary of the Invention
[0004] Based on the technical problems existing in the background technology, the present invention proposes a V-Nb-Ti-O x Nanofibers and their preparation method and application, the present invention is electrospun and then calcined to form vanadium oxide (VO a ), niobium oxide (NbO b ) and titanium oxide (TiO c ) nanofibers (i.e., V-Nb-Ti-O x Nanofibers) can alleviate volume expansion, and through the combination of three oxides, the capacity density, cycle performance, rate performance and capacity of the negative electrode material can be improved.
[0005] The present invention proposes a V-Nb-Ti-O x The nanofibers, vanadium oxide, niobium oxide and titanium oxide are uniformly attached to the carbon nanofibers, wherein the molar ratio of V, Nb and Ti is 1-3:2-4:0.05-0.15.
[0006] Preferably, V-Nb-Ti-O x The diameter of the nanofibers is 300-1000 nm.
[0007] Preferably, the chemical formulas of vanadium oxide, niobium oxide and titanium oxide are VO a 、NbO b 、TiO c , where a is 0-2.5, b is 0-2, and c is 0-2.
[0008] The present invention also proposes the above-mentioned V-Nb-Ti-O x The preparation method of nanofibers includes the following steps: mixing a vanadium source, a niobium source, a titanium source and a solvent to obtain a stock solution, electrospinning the stock solution, and calcining to obtain V-Nb-Ti-O x Nanofibers.
[0009] Preferably, the vanadium source is vanadium acetylacetonate.
[0010] Preferably, the niobium source is niobium oxalate.
[0011] Preferably, the titanium source is tetrabutyl titanate.
[0012] Preferably, the solvent is N,N-dimethylformamide.
[0013] Preferably, in the stock solution, the molar ratio of V, Nb, and Ti is 1-3:2-4:0.05-0.15.
[0014] Preferably, in the stock solution, the ratio of Ti to solvent is 0.05-0.15 mmol:90-150 ml.
[0015] Preferably, the stock solution is defoamed before electrospinning.
[0016] Preferably, the voltage of electrospinning is 12-15 kV, and the feeding speed of the stock solution is 15-17 μm / min.
[0017] Preferably, the calcination procedure is: in an air atmosphere, heating to 280-320° C., keeping warm for 10-20 minutes; then in an inert gas atmosphere, heating to 580-620° C., keeping warm for 10-20 minutes, and then heating to 880-920° C., keeping warm for 300-330 minutes.
[0018] Preferably, the heating rate is 8-10°C / min.
[0019] The present invention also proposes the above-mentioned V-Nb-Ti-O x Application of nanofibers in negative electrode materials.
[0020] Preferably, the invention is used in negative electrode materials of lithium-ion batteries.
[0021] The present invention also proposes a negative electrode material, comprising: the above-mentioned V-Nb-Ti-O x Nanofibers and graphite.
[0022] Preferably, the graphite is artificial graphite.
[0023] Preferably, V-Nb-Ti-O x The weight ratio of nanofiber to graphite is 1:0.8-1.2.
[0024] Preferably, V-Nb-Ti-O x The particle size of the nanofiber is ≤200 mesh.
[0025] The present invention selects appropriate vanadium source, niobium source, titanium source and solvent, and adjusts their dosage ratio to prepare stock solution, and then forms vanadium oxide (VO) during electrostatic spinning and roasting. a ), niobium oxide (NbO b ) and titanium oxide (TiO c ), and it is evenly attached to the carbon nanofibers. Through the coordination of the three oxides, it can provide active sites for lithium ion expansion, shorten the diffusion distance, and improve its rate performance; it can also enhance the cycle performance and increase the specific capacity; thereby achieving a synergistic improvement in the capacity density, cycle performance and rate performance of the negative electrode material;
[0026] In addition, the V-Nb-Ti-Ox nanofibers have a nanostructure effect, which can make the electrode have good electrochemical properties, and the structure of the nanofibers can alleviate volume expansion, so that the assembled electrode has high capacity, good rate performance and long-term cycle stability.
[0027] The present invention adopts electrospinning technology to make vanadium source, niobium source and titanium source into spinning solution, and then prepares nanofibers through electrospinning, thereby giving the material a different structure in essence; this nanostructure can improve conductivity, rate performance and capacity.
[0028] The present invention combines V-Nb-Ti-Ox nanofibers with artificial graphite in a suitable ratio to improve the electrochemical performance thereof. DETAILED DESCRIPTION
[0029] Hereinafter, the technical solutions of the present invention will be described in detail through specific embodiments. However, it should be clearly stated that these embodiments are provided for illustration only and are not to be construed as limiting the scope of the present invention.
[0030] Example 1
[0031] A V-Nb-Ti-O x The method for preparing nanofibers comprises the following steps:
[0032] Mix 30 mL of an N,N-dimethylformamide solution containing 1 mmol of vanadium acetylacetonate, 30 mL of an N,N-dimethylformamide solution containing 2 mmol of niobium oxalate, and 30 mL of an N,N-dimethylformamide solution containing 0.05 mmol of tetrabutyl titanate, and stir for 30 minutes to obtain a stock solution.
[0033] The stock solution was placed in a vacuum drying oven, adjusted to 50°C and a vacuum degree of -0.01 MPa, and vacuum defoamed for 5 hours. The solution was then transferred to a 50 mL syringe for electrospinning. The specific electrospinning process was as follows: a 20G flat-end dispensing needle was used as the spinning needle, aluminum foil was used as the receiving substrate, the distance between the spinning needle and the receiving substrate was 15 cm, the voltage was 12 kV, and the injection rate of the stock solution in the syringe was 15 μm / min.
[0034] The spun fibers received by the aluminum foil were collected, placed in an alumina crucible, placed in a high-temperature oven, and calcined in an air atmosphere to obtain V-Nb-Ti-O x nanofibers;
[0035] The calcination procedure is as follows: in an air atmosphere, heat up to 300°C at a rate of 8°C / min and keep warm for 10 minutes; then in a nitrogen atmosphere, heat up to 600°C at a rate of 8°C / min and keep warm for 10 minutes, and then heat up to 900°C at a rate of 8°C / min and keep warm for 320 minutes.
[0036] The above V-Nb-Ti-O x In the nanofibers, vanadium oxide, niobium oxide, and titanium oxide are uniformly attached to the carbon nanofibers, and their diameter is about 400 nm. The molar ratio of V, Nb, and Ti is 1:2:0.05. The chemical formulas of vanadium oxide, niobium oxide, and titanium oxide are VO a 、NbO b 、TiO c , where a is 0-2.5, b is 0-2, and c is 0-2.
[0037] Preparation of negative electrode materials:
[0038] The above-mentioned V-Nb-Ti-Ox nanofibers were broken up with a wall breaker for 30 minutes, and sieved with a 100-mesh sieve, and the sieved material was retained; artificial graphite powder with a gram capacity of about 355 mAh / g was mixed with the sieved V-Nb-Ti-Ox nanofiber powder in a small mixer in a mass ratio of 1:1 at a speed of 50 r / min for 35 minutes to obtain the negative electrode material.
[0039] Example 2
[0040] A V-Nb-Ti-O xThe method for preparing nanofibers comprises the following steps:
[0041] Take 40 mL of N,N-dimethylformamide solution containing 2 mmol of vanadium acetylacetonate, 40 mL of N,N-dimethylformamide solution containing 3 mmol of niobium oxalate, and 40 mL of N,N-dimethylformamide solution containing 0.10 mmol of tetrabutyl titanate, mix them, and stir for 40 minutes to obtain a stock solution;
[0042] The stock solution was placed in a vacuum drying oven, adjusted to 55°C and a vacuum degree of -0.05 MPa, and vacuum defoamed for 5.5 hours. The solution was then transferred to a 50 mL syringe for electrospinning. The specific electrospinning process was as follows: a 21G flat-end dispensing needle was used as the spinning needle, aluminum foil was used as the receiving substrate, the distance between the spinning needle and the receiving substrate was 17.5 cm, the voltage was 13 kV, and the injection rate of the stock solution in the syringe was 16 μm / min.
[0043] The spun fibers received by the aluminum foil were collected, placed in an alumina crucible, placed in a high-temperature oven, and calcined in an air atmosphere to obtain V-Nb-Ti-O x nanofibers;
[0044] The calcination procedure is as follows: in an air atmosphere, heat up to 280°C at a rate of 9°C / min and keep warm for 15 minutes; then in a nitrogen atmosphere, heat up to 580°C at a rate of 9°C / min and keep warm for 15 minutes, and then heat up to 880°C at a rate of 9°C / min and keep warm for 315 minutes.
[0045] The above V-Nb-Ti-O x In the nanofibers, vanadium oxide, niobium oxide, and titanium oxide are uniformly attached to the carbon nanofibers, with a diameter of about 600 nm. The molar ratio of V, Nb, and Ti is 2:3:0.1. The chemical formulas of vanadium oxide, niobium oxide, and titanium oxide are VO a 、NbO b 、TiO c , where a is 0-2.5, b is 0-2, and c is 0-2.
[0046] Preparation of negative electrode materials:
[0047] The above-mentioned V-Nb-Ti-Ox nanofibers were broken up with a wall breaker for 60 minutes, and sieved with a 100-mesh sieve, and the sieved material was retained; artificial graphite powder with a gram capacity of about 355 mAh / g was mixed with the sieved V-Nb-Ti-Ox nanofiber powder in a small mixer in a mass ratio of 1:1 at a speed of 55 / min for 40 minutes to obtain the negative electrode material.
[0048] Example 3
[0049] A V-Nb-Ti-O x The method for preparing nanofibers comprises the following steps:
[0050] Take 50 mL of N,N-dimethylformamide solution containing 3 mmol of vanadium acetylacetonate, 50 mL of N,N-dimethylformamide solution containing 4 mmol of niobium oxalate, and 50 mL of N,N-dimethylformamide solution containing 0.15 mmol of tetrabutyl titanate, mix them, and stir for 50 minutes to obtain a stock solution;
[0051] The stock solution was placed in a vacuum drying oven, adjusted to 60°C and a vacuum degree of -0.01 MPa, and vacuum defoamed for 6 hours. The solution was then transferred to a 50 mL syringe for electrospinning. The specific electrospinning process was as follows: a 22G flat-end dispensing needle was used as the spinning needle, aluminum foil was used as the receiving substrate, the distance between the spinning needle and the receiving substrate was 20 cm, the voltage was 15 kV, and the injection rate of the stock solution in the syringe was 17 μm / min.
[0052] The spun fibers received by the aluminum foil were collected, placed in an alumina crucible, placed in a high-temperature oven, and calcined in an air atmosphere to obtain V-Nb-Ti-O x nanofibers;
[0053] The calcination procedure is as follows: in an air atmosphere, heat up to 320°C at a rate of 10°C / min and keep warm for 20 minutes; then in a nitrogen atmosphere, heat up to 620°C at a rate of 10°C / min and keep warm for 20 minutes, and then heat up to 920°C at a rate of 10°C / min and keep warm for 330 minutes.
[0054] The above V-Nb-Ti-O x In the nanofibers, vanadium oxide, niobium oxide, and titanium oxide are uniformly attached to the carbon nanofibers, and their diameter is about 400 nm. The molar ratio of V, Nb, and Ti is 3:4:0.15. The chemical formulas of vanadium oxide, niobium oxide, and titanium oxide are VO a 、NbO b 、TiO c , where a is 0-2.5, b is 0-2, and c is 0-2.
[0055] Preparation of negative electrode materials:
[0056] The above-mentioned V-Nb-Ti-Ox nanofibers were broken up with a wall breaker for 30 minutes, and sieved with a 100-mesh sieve, and the sieved material was retained; artificial graphite powder with a gram capacity of about 355 mAh / g was mixed with the sieved V-Nb-Ti-Ox nanofiber powder in a small mixer in a mass ratio of 1:1 at a speed of 50 r / min for 35 minutes to obtain the negative electrode material.
[0057] Comparative Example 1
[0058] A negative electrode material, which is the artificial graphite powder in Example 1.
[0059] Comparative Example 2
[0060] No vanadium acetylacetonate was added, and the other steps were the same as in Example 1.
[0061] Comparative Example 3
[0062] Niobium oxalate was not added, and other procedures were the same as in Example 1.
[0063] Comparative Example 4
[0064] Vanadium acetylacetonate and niobium oxalate were not added, and the other procedures were the same as in Example 1.
[0065] The negative electrode materials prepared in Examples 1-3 and Comparative Examples 1-4 were used to prepare button-type batteries CR 2016, respectively. The specific steps were as follows: the negative electrode material was stirred and mixed with conductive carbon black and binder polyvinylidene fluoride in a mass ratio of 80:10:10, and then mixed with an appropriate amount of N-methylpyrrolidone to obtain a negative electrode slurry; the negative electrode slurry was evenly coated on a pre-punched copper foil, dried in a vacuum drying oven at 110° C. for 12 h, and then weighed. The slurry was used as the positive electrode of a simulated battery, the metal lithium sheet was used as the negative electrode, the separator was Celgard 2400, and the electrolyte was a 1 mol / L LiPF6 solution (the solvent was equal volumes of EC and DMC). The slurry was assembled into a button-type battery CR 2016 in an argon-filled, deoxygenated and dehydrated glove box.
[0066] The button cells in each group were tested for capacity, initial efficiency, and cycling performance at 3C / 1C, 2C / 1C, and 1C / 1C rates. The test results are shown in Table 1.
[0067] Table 1 Test results
[0068]
[0069]
[0070] As can be seen from Table 1, the V-Nb-Ti-Ox nanofibers prepared in the present invention can be combined with artificial graphite as negative electrode materials to improve the capacity, initial efficiency and cycle performance of lithium-ion batteries.
[0071] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.
Claims
1. A V-Nb-Ti-O x Nanofibers, characterized in that Vanadium oxide, niobium oxide and titanium oxide are uniformly attached to the carbon nanofiber, wherein the molar ratio of V, Nb and Ti is 1-3:2-4:0.05-0.
15.
2. V-Nb-Ti-O according to claim 1 x Nanofibers, characterized in that V-Nb-Ti-O x The diameter of the nanofibers is 300-1000 nm.
3. V-Nb-Ti-O according to claim 1 or 2 x Nanofibers, characterized in that The chemical formulas of vanadium oxide, niobium oxide, and titanium oxide are VO a 、NbO b 、TiO c , where a is 0-2.5, b is 0-2, and c is 0-2.
4. A V-Nb-Ti-O as claimed in any one of claims 1 to 3 x The method for preparing nanofibers is characterized in that: The method comprises the following steps: mixing a vanadium source, a niobium source, a titanium source and a solvent to obtain a stock solution, electrospinning the stock solution, and calcining the solution to obtain a V-Nb-Ti-O x Nanofibers.
5. V-Nb-Ti-O according to claim 4 x The method for preparing nanofibers is characterized in that: The vanadium source is vanadium acetylacetonate; preferably, the niobium source is niobium oxalate; preferably, the titanium source is tetrabutyl titanate; preferably, the solvent is N,N-dimethylformamide.
6. V-Nb-Ti-O according to claim 4 or 5 x The method for preparing nanofibers is characterized in that: In the stock solution, the molar ratio of V, Nb, and Ti is 1-3:2-4:0.05-0.15; preferably, in the stock solution, the amount ratio of Ti to solvent is 0.05-0.15 mmol:90-150 ml.
7. The V-Nb-Ti-O according to any one of claims 4 to 6. x The method for preparing nanofibers is characterized in that: After defoaming, the stock solution is subjected to electrostatic spinning; preferably, the voltage of the electrostatic spinning is 12-15 kV, and the feeding speed of the stock solution is 15-17 μm / min.
8. The V-Nb-Ti-O according to any one of claims 4 to 7. x The method for preparing nanofibers is characterized in that: The calcination procedure is as follows: in an air atmosphere, heating to 280-320°C and keeping warm for 10-20 minutes; then in an inert gas atmosphere, heating to 580-620°C and keeping warm for 10-20 minutes, and then heating to 880-920°C and keeping warm for 300-330 minutes; preferably, the heating rate is 8-10°C / min.
9. A V-Nb-Ti-O as claimed in any one of claims 1 to 3 x Application of nanofibers in negative electrode materials; preferably, application in negative electrode materials for lithium-ion batteries.
10. A negative electrode material, characterized in that: include: The V-Nb-Ti-O according to any one of claims 1 to 3 x Nanofibers and graphite; preferably, the graphite is artificial graphite; preferably, V-Nb-Ti-O x The weight ratio of nanofibers to graphite is 1:0.8-1.2; preferably, V-Nb-Ti-O x The particle size of the nanofiber is ≤200 mesh.