A method for preparing one-dimensional Nb2O5 nanorod materials

Abstract

The application provides a preparation method of one-dimensional Nb2O5 nanorod material and belongs to the technical field of nanometer materials. The method comprises the following steps: uniformly dispersing a niobium source in anhydrous ethanol to obtain a turbid solution; uniformly dispersing oleic acid in the turbid solution to obtain reaction liquid 1; performing a solvothermal reaction on the reaction liquid 1, collecting a solid product; and calcining the solid product to obtain the one-dimensional Nb2O5 nanorod material. The one-dimensional Nb2O5 nanorod material is precisely synthesized for the first time under the synergistic regulation of an anhydrous ethanol and an oleic acid double-solvent system, and the one-dimensional Nb2O5 nanorod material has excellent cycle stability as a lithium ion battery negative electrode material.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and in particular to a method for preparing one-dimensional Nb2O5 nanorod materials. Background Technology

[0002] Niobium pentoxide (Nb₂O₅) is an important transition metal oxide that has attracted widespread attention in the field of electrode materials due to its unique electrochemical properties. Nb₂O₅ exhibits high chemical stability, making it suitable for various electrochemical energy storage systems, such as lithium-ion batteries, sodium-ion batteries, and supercapacitors. However, the low conductivity of Nb₂O₅ and the difficulty in controlling its optimal crystal structure limit its application in electrochemical energy storage. Studies have shown that controlling the morphology and microstructure of electrode materials at a fine level can improve their conductivity. For niobium pentoxide, a one-dimensional linear morphology can not only significantly increase the specific surface area of ​​the material but also provide a fast path for electron and ion transport, reducing charge transfer resistance and thus improving its electrochemical performance. Summary of the Invention

[0003] To address the inherent low conductivity of niobium pentoxide (Nb2O5) and the current market demand for high-performance lithium-ion battery electrode materials, this invention provides a method for preparing orthorhombic one-dimensional Nb2O5 nanorods that can be used as a negative electrode material for lithium-ion batteries. This method involves researching and designing the specific steps, process parameters, and product structure of the preparation process.

[0004] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is a method for preparing one-dimensional Nb₂O₅ nanorod materials, comprising the following steps: The niobium source was uniformly dispersed in anhydrous ethanol to obtain a turbid liquid; Oleic acid was uniformly dispersed in the turbid liquid to obtain reaction solution 1; The reaction solution 1 was subjected to a solvothermal reaction, and the solid product was collected. The solid product was calcined to obtain the one-dimensional Nb2O5 nanorod material.

[0005] In a preferred embodiment of the present invention, the niobium source is ammonium niobate oxalate hydrate.

[0006] In a preferred embodiment of the present invention, the mass-to-volume ratio of the niobium source and anhydrous ethanol is 1.5 g:10 mL.

[0007] In a preferred embodiment of the present invention, the volume ratio of anhydrous ethanol to oleic acid is 10:1~3.

[0008] In a preferred embodiment of the present invention, the temperature of the solvothermal reaction is 160–200 °C and the time is 12–24 h.

[0009] In a preferred embodiment of the present invention, before calcining the solid product, the method further includes washing and drying the solid product. The present invention does not impose special limitations on the washing and drying methods and parameters; conventional techniques skilled in the art can be used, such as washing with anhydrous ethanol and deionized water respectively to remove impurities, and drying at 80 °C for 12 hours.

[0010] In a preferred embodiment of the present invention, the calcination temperature is 500-600 °C and the time is 2 h.

[0011] The present invention does not impose any special limitation on the above-mentioned uniform dispersion method; conventional technical means known to those skilled in the art can be used, such as stirring.

[0012] The second technical solution of the present invention is a one-dimensional Nb2O5 nanorod material prepared by the above preparation method.

[0013] The present invention discloses the following technical effects: (1) This invention utilizes the structural feature that the double bond in the oleic acid molecule can cause the bending of the spatial structure, thereby generating a spatial barrier. Oleic acid is used as a surfactant and is miscible with ethanol solvent to stabilize the nanoparticles generated during the preparation process and prevent the nanoparticles from agglomerating. For the first time, one-dimensional Nb2O5 nanorods were accurately synthesized under the synergistic regulation of the anhydrous ethanol and oleic acid dual solvent system.

[0014] (2) The raw materials of this invention are readily available, the cost is low, the preparation process is simple, and the reaction conditions are mild. Compared with the preparation of one-dimensional Nb2O5 nanorods reported, the hydrothermal reaction time is shortened, the calcination temperature is reduced, the use of template agent is eliminated, the process is easy to control, and it has high feasibility.

[0015] (3) The one-dimensional Nb2O5 nanorod material synthesized in this invention has excellent cycle stability as a negative electrode material for lithium-ion batteries. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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.

[0017] Figure 1 The image shows the XRD pattern of the one-dimensional Nb₂O₅ nanorod material prepared in Example 1 of this invention. Figure 2 This is a SEM image of the one-dimensional Nb₂O₅ nanorod material prepared in Example 1 of this invention; Figure 3 The cycling stability diagram is shown for the one-dimensional Nb2O5 nanorod material prepared in Example 1 of this invention. Figure 4 The cycling stability diagrams are for the one-dimensional Nb2O5 nanorod materials prepared in Examples 1-4 and Comparative Example 1 of this invention. Detailed Implementation

[0018] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0019] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0020] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0021] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0022] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0023] This invention primarily uses ammonium niobate oxalate hydrate, oleic acid, and ethanol as raw materials, employing a combination of solvothermal reaction and high-temperature calcination to prepare one-dimensional Nb₂O₅ nanomaterials. The specific steps are as follows: (1) Add 1.5 g of niobium source (ammonium niobate oxalate hydrate) to every 10 mL of anhydrous ethanol and distribute the niobium source evenly in the anhydrous ethanol under stirring conditions to form a white turbid liquid.

[0024] (2) Add 1 to 3 mL of oleic acid to the white turbid liquid formed in step (1) for every 10 mL of anhydrous ethanol, and continue stirring for 4 h until the oleic acid is evenly distributed in the solution.

[0025] (3) Place the solution from step (2) into a stainless steel high-pressure reactor with a polytetrafluoroethylene liner and react at 160-200 °C for 12-24 h.

[0026] (4) After cooling to room temperature, remove the reaction vessel, filter the solution, wash it several times with anhydrous ethanol and deionized water to remove impurities, and then dry it at 80 °C for 12 h to obtain a white powder.

[0027] (5) The white powder obtained in step (4) is calcined in a muffle furnace at 500-600 °C for 2 h to obtain one-dimensional Nb2O5 nanorod material.

[0028] In this invention, oleic acid is used as a surfactant in synergistic action with ethanol solvent to prepare one-dimensional Nb₂O₅ nanorods. By controlling key parameters such as the proportions of each component, the temperature and time of the hydrothermal reaction, and the temperature and time of calcination within a certain range, the morphology and purity of the prepared one-dimensional Nb₂O₅ nanorods can be guaranteed, while simultaneously increasing the reaction rate, thereby ultimately improving the overall electrochemical performance of this electrode material. If the parameters are outside the range of this invention, the expected Nb₂O₅ nanorods cannot be obtained. For example, insufficient oleic acid leads to product agglomeration, while excessive oleic acid results in nanorods that are too short.

[0029] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0030] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0031] Example 1 (1) Preparation of Nb2O5 materials Under strong magnetic stirring, 3.0 g of ammonium oxalate hydrate was added to 20 mL of anhydrous ethanol, forming a white turbid liquid. Then, 3 mL of oleic acid was added dropwise to the white turbid liquid. After the addition was complete, stirring continued for 4 h until the oleic acid was uniformly mixed in the white turbid liquid. The liquid was then transferred to a 50 mL stainless steel high-pressure reactor with a polytetrafluoroethylene liner and reacted at 180 °C for 24 h. After cooling to room temperature, the reactor was removed, and the product was filtered. It was washed several times with anhydrous ethanol and deionized water to remove impurities, and then dried at 80 °C for 12 h to obtain a white powder. This white powder was calcined in a muffle furnace at 600 °C for 2 h to obtain one-dimensional Nb₂O₅ nanorods (e.g., ...). Figure 1 , 2 As shown). Its crystal structure is an orthorhombic phase structure (as shown). Figure 1 (As shown).

[0032] (2) Electrochemical testing Weigh the above-mentioned one-dimensional Nb₂O₅ nanorod material, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Grind them in an agate mortar for about 15 minutes to ensure uniform mixing. Then, add N-methylpyrrolidone (NMP) as a dispersant and mix evenly. Coat the mixed active material evenly onto a copper foil. Pre-dry the copper foil loaded with the active material under an infrared lamp until the NMP on the surface evaporates. Cut the copper foil into circular electrode pieces with a diameter of 1.1 cm using a cutting machine. Place them in a vacuum drying oven for secondary drying at 120 °C for 12 hours, followed by natural cooling. After drying, weigh and record the mass of active material in each electrode piece. Select a loading of 0.8 mg / cm³. -1 The electrode plates are used to mount the battery.

[0033] The electrode plates were assembled into a coin cell in a glove box filled with argon gas. The electrolyte used was a 1 mol L⁻¹ solvent. -1 A LiPF6 solution was prepared, with ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 volume ratio. The performance of the electrode under test was evaluated using a Land-2001B battery tester. The voltage range was 0.01–3 V, and the cycle life was tested at 1 A g. -1 Charge-discharge cycles are performed at current densities. For example... Figure 3 As shown, this material at 1 A g -1 Constant current charge-discharge tests were conducted at the current density, and the discharge capacity only decreased in the first twenty cycles. In the subsequent nearly one thousand charge-discharge cycles, the discharge capacity remained almost unchanged at 275.6 mAh g⁻¹. -1 .

[0034] Example 2 (1) Preparation of Nb2O5 materials Under strong magnetic stirring, 3.0 g of ammonium oxalate hydrate was dissolved in 20 mL of anhydrous ethanol to form a white turbid liquid. Then, 6 mL of oleic acid was added dropwise to the white turbid liquid. After the addition was complete, stirring continued for 4 h until the oleic acid was uniformly mixed in the white turbid liquid. The liquid was transferred to a 50 mL stainless steel high-pressure reactor with a polytetrafluoroethylene liner and reacted at 180 °C for 24 h. After cooling to room temperature, the reactor was removed, and the product was filtered. It was washed several times with anhydrous ethanol and deionized water to remove impurities, and then dried at 80 °C for 12 h to obtain a white powder. This white powder was calcined in a muffle furnace at 600 °C for 2 h to obtain one-dimensional Nb₂O₅ rod nanomaterials (i.e., the difference from Example 1 is that the volume ratio of anhydrous ethanol to oleic acid was adjusted from 10:1.5 to 10:3).

[0035] (2) Electrochemical testing Weigh the above-mentioned one-dimensional Nb₂O₅ nanorod material, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Grind them in an agate mortar for about 15 minutes to ensure uniform mixing. Then, add N-methylpyrrolidone (NMP) as a dispersant and mix evenly. Coat the mixed active material evenly onto a copper foil. Pre-dry the copper foil loaded with the active material under an infrared lamp until the NMP on the surface evaporates. Cut the copper foil into circular electrode pieces with a diameter of 1.1 cm using a cutting machine. Place them in a vacuum drying oven for secondary drying at 120 °C for 12 hours, followed by natural cooling. After drying, weigh and record the mass of active material in each electrode piece. Select a loading of 0.8 mg / cm³. -1 The electrode plates are used to mount the battery.

[0036] The electrode plates were assembled into a coin cell in a glove box filled with argon gas. The electrolyte used was a 1 mol L⁻¹ solvent. -1 A LiPF6 solution was prepared, with ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 volume ratio. The performance of the electrode under test was evaluated using a Land-2001B battery tester. The voltage range was 0.01–3 V, and the cycle life was tested at 1 A g. -1 The discharge capacity was subjected to charge-discharge cycles at a current density of [value missing]. After a relatively rapid decay in the first fifteen cycles, the discharge capacity tended to stabilize. After 600 charge-discharge cycles, the capacity decay accelerated again. After 1000 charge-discharge cycles, the discharge capacity was 176.5 mAh g⁻¹. -1 ( Figure 4 ).

[0037] Example 3 (1) Preparation of Nb2O5 materials Under strong magnetic stirring, 3.0 g of ammonium oxalate hydrate was dissolved in 20 mL of anhydrous ethanol to form a white turbid liquid. Then, 3 mL of oleic acid was added dropwise to the white turbid liquid. After the addition was complete, stirring continued for 4 h until the oleic acid was uniformly mixed in the white turbid liquid. The liquid was transferred to a 50 mL stainless steel high-pressure reactor with a polytetrafluoroethylene liner and reacted at 160 °C for 12 h. After cooling to room temperature, the reactor was removed, and the product was filtered. It was washed several times with anhydrous ethanol and deionized water to remove impurities, and then dried at 80 °C for 12 h to obtain a white powder. This white powder was calcined in a muffle furnace at 600 °C for 2 h to obtain one-dimensional Nb₂O₅ rod nanomaterials (i.e., the difference from Example 1 is that the solvothermal reaction parameters were adjusted from 180 °C for 24 h to 160 °C for 12 h).

[0038] (2) Electrochemical testing Weigh the above-mentioned one-dimensional Nb₂O₅ nanorod material, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Grind them in an agate mortar for about 15 minutes to ensure uniform mixing. Then, add N-methylpyrrolidone (NMP) as a dispersant and mix evenly. Coat the mixed active material evenly onto a pre-prepared copper foil. Pre-dry the copper foil under an infrared lamp until the NMP on the surface evaporates. Cut the copper foil into circular electrode pieces with a diameter of 1.1 cm using a cutting machine. Place them in a vacuum drying oven for secondary drying at 120℃ for 12 hours, then allow them to cool naturally. After drying, weigh and record the mass of active material in each electrode piece. Select a loading of 0.8 mg / cm³. -1 The electrode plates are used to mount the battery.

[0039] The electrode sheets were assembled into a coin cell in a glove box under argon atmosphere. The electrolyte used was a 1 mol L⁻¹ solvent. -1 A LiPF6 solution was prepared, with ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 volume ratio. The performance of the electrode under test was evaluated using a Land-2001B battery tester. The voltage range was 0.01–3 V, and the cycle life was tested at 1 A g. -1 The device underwent charge-discharge cycles at a current density of [value missing]. Its discharge capacity decreased rapidly after the first 160 cycles before stabilizing. After 1000 cycles, the discharge capacity was 257.2 mAh g. -1 ( Figure 4 ).

[0040] Example 4 (1) Preparation of Nb2O5 materials Under strong magnetic stirring, 3.0 g of ammonium oxalate hydrate was dissolved in 20 mL of anhydrous ethanol to form a white turbid liquid. Then, 3 mL of oleic acid was added dropwise to the white turbid liquid. After the addition was complete, stirring continued for 4 h until the oleic acid was uniformly mixed in the white solution. The liquid was transferred to a 50 mL stainless steel high-pressure reactor with a polytetrafluoroethylene liner and reacted at 200 °C for 16 h. After cooling to room temperature, the reactor was removed, and the product was filtered. It was washed several times with anhydrous ethanol and deionized water to remove impurities, and then dried at 80 °C for 12 h to obtain a white powder. This white powder was calcined in a muffle furnace at 600 °C for 2 h to obtain one-dimensional Nb₂O₅ nanorods (the difference from Example 1 is that the solvothermal reaction parameters were adjusted from 180 °C for 24 h to 200 °C for 16 h).

[0041] (2) Electrochemical testing Weigh the above-mentioned one-dimensional Nb₂O₅ nanorod material, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Grind them in an agate mortar for about 15 minutes to ensure uniform mixing. Then, add N-methylpyrrolidone (NMP) as a dispersant and mix evenly. Coat the mixed active material evenly onto a copper foil. Pre-dry the copper foil loaded with the active material under an infrared lamp until the NMP on the surface evaporates. Cut the copper foil into circular electrode pieces with a diameter of 1.1 cm using a cutting machine. Place them in a vacuum drying oven for secondary drying at 120 °C for 12 hours, followed by natural cooling. After drying, weigh and record the mass of active material in each electrode piece. Select a loading of 0.8 mg / cm³. -1 The electrode plates are used to mount the battery.

[0042] The electrode sheets were assembled into a coin cell in a glove box under argon atmosphere. The electrolyte used was a 1 mol L⁻¹ solvent. -1 A LiPF6 solution was prepared, with ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 volume ratio. The performance of the electrode under test was evaluated using a Land-2001B battery tester. The voltage range was 0.01–3 V, and the cycle life was tested at 1 A g. -1 The device was subjected to charge-discharge cycles at a current density of [value missing]. Its discharge capacity decreased rapidly after the first fourteen charge-discharge cycles, then stabilized. After 650 charge-discharge cycles, the discharge capacity was 192.1 mAh g⁻¹. -1 ( Figure 4 ).

[0043] Comparative Example 1 (1) Preparation of Nb2O5 materials The only difference from Example 1 is that the addition of oleic acid is omitted; all other steps and parameters are the same as in Example 1.

[0044] (2) Electrochemical testing Weigh the above-mentioned active material Nb₂O₅ nanorods, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. Grind them in an agate mortar for about 15 minutes to ensure uniform mixing. Then, add N-methylpyrrolidone (NMP) as a dispersant and mix evenly. Coat the mixed active material evenly onto a copper foil. Pre-dry the copper foil under an infrared lamp until the NMP on the surface evaporates. Cut the copper foil into circular electrode pieces with a diameter of 1.1 cm using a cutting machine. Place them in a vacuum drying oven for secondary drying at 120 °C for 12 hours, followed by natural cooling. After drying, weigh and record the mass of active material in each electrode piece. Select a loading of 0.8 mg / cm³. -1 The electrode plates are used to mount the battery.

[0045] The electrode plates were assembled into a coin cell in a glove box filled with argon gas. The electrolyte used was a 1 mol L⁻¹ solvent. -1 A LiPF6 solution was prepared, with ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 volume ratio. The performance of the electrode under test was evaluated using a Land-2001B battery tester. The voltage range was 0.01–3 V, and the cycle life was tested at 1 A g. -1 It was subjected to charge-discharge cycles at a current density of [value missing]. Its initial discharge capacity was 322.3 mAh g⁻¹. -1 ( Figure 4 After 500 charge-discharge cycles, the capacity decayed to 228.1 mAh g. -1 Its initial discharge capacity and cycle performance are significantly lower than those of Example 1.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing one-dimensional Nb₂O₅ nanorod materials, characterized in that, Includes the following steps: The niobium source was uniformly dispersed in anhydrous ethanol to obtain a turbid liquid; Oleic acid was uniformly dispersed in the turbid liquid to obtain reaction solution 1; The reaction solution 1 was subjected to a solvothermal reaction, and the solid product was collected. The solid product was calcined to obtain the one-dimensional Nb2O5 nanorod material. The volume ratio of anhydrous ethanol to oleic acid is 10:1~3; The solvothermal reaction is carried out at a temperature of 160–200°C for a duration of 12–24 h. The calcination temperature is 500–600 °C, and the time is 2 h.

2. The preparation method according to claim 1, characterized in that, The niobium source is ammonium oxalate hydrate.

3. The preparation method according to claim 1, characterized in that, The mass-to-volume ratio of the niobium source and anhydrous ethanol is 1.5 g: 10 mL.

4. The preparation method according to claim 1, characterized in that, Before calcining the solid product, the process further includes washing and drying the solid product.

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