Nano-selenium-iron assembled micro-scale material, preparation method and application thereof

Abstract

The application relates to a nanometer ferroselenide assembled microscale material, a preparation method and application. The application discloses a nanometer ferroselenide secondary stacking material, a preparation method and application thereof. The material has a three-dimensional structure, and the three-dimensional porous structure is formed by stacking of ferroferric oxide nanospheres. The preparation method is as follows: iron source containing ferric ions is added into ethylene glycol, and the ferroferric oxide nanometer material with secondary stacking can be obtained through a one-step method. The material is coated by dopamine hydrochloride. Metal ions introduced at the same time generate hydrogen selenide gas in a high-temperature heating process, and ferroselenide nanoparticles are generated in situ. The nanometer ferroselenide secondary stacking material provided by the application has excellent performance on a sodium ion battery and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the technical field of sodium-ion battery anode materials, specifically relating to a nano-iron selenide assembly micron-scale material, the preparation method of the assembly material, and its application as a sodium-ion battery anode material. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Limited lithium resources and high lithium costs severely hinder the practical application of lithium-ion batteries in energy storage. Currently, sodium-ion batteries are considered a promising alternative to lithium-ion batteries due to their low cost, high storage capacity, and environmental friendliness. However, during charging / discharging, compared to lithium-ion batteries, sodium ions have a larger radius and heavier molar mass, making diffusion in electrode materials more difficult and causing greater volume changes. This places higher demands on sodium-ion battery anode materials. Currently, commonly used sodium-ion battery anode materials mainly fall into four categories: carbon-based materials (soft carbon / hard carbon, etc.), transition metal compounds, alloy anodes, and organic compounds. Among these, metal compounds primarily achieve sodium storage through conversion and alloying reactions, but they experience significant volume expansion during cycling, leading to electrode material pulverization and collapse, posing certain safety hazards. Therefore, providing an anode material with good cycle stability and fast charging capability is of great significance in addressing the problems associated with metal compound anode materials.

[0004] Among current anode materials, metal selenides have attracted widespread attention due to their high specific capacity, low polarization characteristics, and suitable voltage platform. However, these materials suffer from poor conductivity and volume effects during charge and discharge, making it difficult to achieve long-term cycle stability and fast-charging performance. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the present invention aims to provide a material composed of nano-iron selenide assembled into microrods, its preparation method, and its applications. The nano-iron selenide secondary stacking material provided by the present invention is suitable for sodium-ion batteries with long cycle life and high rate performance.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a nano-iron selenide assembly micron-scale material, wherein the assembly material is formed by stacking nano-sized iron selenide microspheres in a three-dimensional columnar shape, and the columnar structure has a size at the micron level.

[0008] fromFigure 1 As can be seen, in this assembled material, nanoscale iron selenide microspheres (~10 nm) are interconnected to form a relatively loose columnar structure with certain gaps. This loose spatial structure allows space for the material to expand during cycling, which can effectively improve the cycle stability of the charge-discharge process. Furthermore, the iron selenide microspheres have uniform carbon coating, which effectively improves the conductivity of the material.

[0009] The second aspect is that the preparation method of the assembly material described in the first aspect includes the following steps: adding polyethylene glycol dropwise to an ethylene glycol solution containing iron ions, mixing thoroughly, adding a certain amount of sodium acetate and continuing to stir, then transferring the mixed solution to a hydrothermal reactor, heating to 180-220°C, and reacting for 45-50 hours; adding the hydrothermal reaction product and dopamine hydrochloride to a buffer solution, mixing thoroughly and drying, and calcining the dried sample together with selenium to obtain the above-mentioned assembly material.

[0010] In the development of the above-mentioned assembly materials, this invention uses sodium acetate to provide an alkaline environment to promote the precipitation of iron ions, and polyethylene glycol as a morphology control agent to control the generation of the desired morphology.

[0011] The above preparation method has the following preferred technical solutions:

[0012] The preferred source of the iron ions is an inorganic salt, such as ferric sulfate, ferric chloride, or ferric nitrate. Those skilled in the art can make conventional selections based on factors such as cost. In one exemplary embodiment of the present invention, ferric chloride is used as the iron source. In this embodiment, the concentration of the ferric chloride ethylene glycol solution is 0.1–0.5 mol·L⁻¹. -1 The two components should be mixed evenly using mechanical stirring. After adding polyethylene glycol, stirring should continue to ensure thorough mixing and a homogeneous solution. The dosage ratio of ethylene glycol, ferric chloride, polyethylene glycol, and sodium acetate is 50-300 ml: 1-6 g: 0.5-4 g: 0.1-2 g. In schemes using other inorganic salts as the iron source, the molar mass can be converted based on the above mass ratio.

[0013] After the product of the above hydrothermal reaction is removed, washed and dried, it is added to a Tris solution and stirred evenly. Then, dopamine hydrochloride is added and stirring continues. As the stirring time is extended, the solution gradually darkens from brownish-red to brownish-black, and stirring is stopped. The product obtained by stirring is washed and dried. In the above steps, the concentration of the Tris solution is 8-12 mM; the mass ratio of the product to dopamine hydrochloride is 5-10:1; and the stirring time is 3-12 h.

[0014] The calcination process described above takes place at a temperature of 500-700℃, using a uniform heating method with a heating rate of 2-4℃ / min. The calcination time is 5-7 hours. A reducing gas atmosphere, such as hydrogen, is used during the calcination process. However, for safety reasons, hydrogen argon may be used in actual production. During the selenization process, the mass ratio of the sample to selenium powder is 3-20:1. During the selenization process, the selenium powder is placed at the upwind end of the heating zone.

[0015] Thirdly, the assembly material described in the first aspect is provided as an application of the anode material for sodium-ion batteries.

[0016] Fourthly, a sodium-ion battery, a 2032 type button cell, is provided, wherein the battery uses the assembly material described in the first aspect as the negative electrode.

[0017] This invention verifies the electrochemical performance of the above-mentioned assembled materials. The results show that the negative electrode material has good specific capacity and cycle stability. In the feasible embodiment of the above-mentioned sodium-ion battery, the positive electrode is metallic sodium, and the separator is selected from polyolefin composite separators, glass fiber filter paper type separators, or organic polymer nonwoven fabric type separators. The sodium salt in the electrolyte is selected from fluorine-containing sodium salts (NaPF6, NaOTF, NaFSI, NaTFSI, etc.), boron-containing sodium salts (NaBF4, NaBOB, NaDFOB, etc.) or other sodium salts (NaClO4, etc.). The solvent of the electrolyte is an ether solvent or an ester solvent. Among them, the ether solvents are mainly DME (ethylene glycol dimethyl ether) and DOL (dioxolane), etc.; the ester solvents are mainly PC (propylene carbonate), EC (ethylene carbonate), DEC (diethyl carbonate), etc.

[0018] The beneficial effects of one or more of the above technical solutions are:

[0019] 1) This invention selects ferric chloride as the iron source and selenium powder as the selenium source, making preparation simple and using inexpensive and readily available raw materials; 2) This invention obtains iron(III) oxide nanomaterials with secondary assembly in a one-step process by adding an iron source containing ferric ions to ethylene glycol. Furthermore, it is coated with dopamine hydrochloride. Simultaneously, the hydrogen selenide gas generated during the high-temperature heating process of the selenium powder can reduce the metal particles to iron selenide nanoparticles in situ. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a scanning electron microscope image of the iron selenide assembly micron-scale material prepared in Example 1;

[0022] Figure 2This demonstrates the application of the iron selenide assembly micron-scale material prepared in Example 1 in the anode of a sodium-ion battery. Detailed Implementation

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] As described in the background section, current metal compound-based sodium-ion battery anode materials suffer from insufficient conductivity and poor charge-discharge cycle stability. This invention provides a nano-sized iron selenide-assembled micron-scale material, which, when combined with carbon materials, effectively improves the conductivity of iron selenide and can be used as an anode material for sodium-ion batteries.

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0027] Example 1: Preparation of Nano-Iron Selenide Secondary Stacking Material

[0028] (1) Prepare a solution with 0.2 mol·L⁻¹ -1 A ferric chloride ethylene glycol solution is mixed thoroughly and evenly with magnetic stirring to obtain a metal salt solution.

[0029] (2) Add polyethylene glycol dropwise to the above solution, stir magnetically, mix thoroughly, and obtain a homogeneous solution.

[0030] (3) Continue to add 0.5g of sodium acetate to the above solution and continue stirring to obtain a homogeneous solution.

[0031] (4) Transfer the above mixed solution into a polytetrafluoroethylene reactor and seal it. Place the sealed reactor in a forced-air drying oven and heat it to 200°C for 48 hours.

[0032] (5) Take out the product from the cooled reaction vessel, centrifuge and wash it, and dry it; weigh the dried sample as 400 mg.

[0033] (6) Prepare a 10mM tris solution at room temperature, add the dried product to the solution and stir. After stirring for a certain period of time, add 100mg of dopamine hydrochloride to the solution and continue to stir magnetically. Then, centrifuge, wash and dry.

[0034] (7) The dried sample was transferred to a tube furnace for heating. Selenium powder was placed in a quartz boat and placed at the upper air vent of the tube furnace. Selenization was carried out for 6 hours (selenium powder was the selenium source and the selenization temperature was 600℃) to obtain micron-sized iron selenide rods with nanosphere assembly.

[0035] The adopted version Figure 1 As shown, active particles with a size of ~10nm are assembled together to form a one-dimensional columnar structure, and the particles stacked together form a porous structure.

[0036] Example 2

[0037] (1) Prepare a solution with 0.5 mol·L -1 A ferric chloride ethylene glycol solution is mixed thoroughly and evenly with magnetic stirring to obtain a metal salt solution.

[0038] (2) Add ethylene glycol dropwise to the above solution, stir magnetically, mix thoroughly, and obtain a homogeneous solution.

[0039] (3) Continue to add 0.8g of sodium acetate to the above solution and continue stirring to obtain a homogeneous solution.

[0040] (4) Transfer the above mixed solution to a polytetrafluoroethylene reactor and seal it. Place the sealed reactor in a forced-air drying oven and heat it at 180°C for 50 hours.

[0041] (5) Take out the product from the cooled reaction vessel, centrifuge and wash it, and dry it; weigh the dried sample as 800 mg.

[0042] (6) Prepare a 10mM tris solution at room temperature, add the dried product to the solution and stir. After stirring for a certain period of time, add 150mg of dopamine hydrochloride to the solution and continue to stir magnetically. Then, centrifuge, wash and dry.

[0043] (7) The dried sample was transferred to a tube furnace for heating. Selenium powder was placed in a quartz boat and placed at the upper air vent of the tube furnace. Selenization was carried out for 6 hours (selenium powder was the selenium source and the selenization temperature was 600℃) to obtain micron-sized iron selenide rods with nanosphere assembly.

[0044] Example 3 Sodium-ion battery

[0045] The iron selenide composite material prepared in Example 1 was used as the anode material for sodium-ion batteries, assembled at the micron scale. Metallic sodium, glass fiber, and 1M NaPF6 were used as the counter electrode, separator, and electrolyte in a DME, respectively, to assemble a 2032-type coin cell. Discharge and charge tests were performed on a LAND-BT2013A measurement system within a potential range of 0.01-3V at a current density of 5Ag. -1 At that time, 280mAh g can be obtained. -1 It has a high specific capacity and can stably cycle for 2000 times.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing nano-sized iron selenide assembled micron-scale materials, characterized in that, The material is formed by stacking nano-sized iron selenide microspheres in a three-dimensional columnar shape, with the columnar structure reaching the micrometer level in size. The process includes the following steps: adding polyethylene glycol dropwise to an ethylene glycol solution containing iron ions, mixing thoroughly, adding a certain amount of sodium acetate and stirring continuously, then transferring the mixed solution to a hydrothermal reactor, heating to 180~220℃, and reacting for 45~50 hours; adding the hydrothermal reaction product and dopamine hydrochloride to a buffer solution, mixing thoroughly, and drying; calcining the dried sample together with selenium to obtain nano-iron selenide assembled micron-scale materials; The calcination temperature is 500-700℃, and a uniform heating method is adopted with a heating rate of 2-4℃ / min; the calcination time is 5-7h, and a reducing gas atmosphere selected from hydrogen or hydrogen-argon is used during the calcination process; during the selenization process, the mass ratio of the sample to selenium powder is 3-20:

1. The iron ions are sourced from ferric chloride; the dosage ratio of ethylene glycol, ferric chloride, polyethylene glycol, and sodium acetate is 50-300 ml: 1-6 g: 0.5-4 g: 0.1-2 g.

2. The preparation method according to claim 1, characterized in that, Ferric chloride was used as the iron source, and the concentration of the ferric chloride ethylene glycol solution was 0.1–0.5 mol·L⁻¹. -1 The two should be mixed evenly by mechanical stirring; after adding polyethylene glycol, stirring should continue to ensure thorough mixing to obtain a homogeneous solution.

3. The preparation method according to claim 1, characterized in that, The product of the hydrothermal reaction is removed, washed, dried, added to a Tris solution and stirred evenly. Then, dopamine hydrochloride is added and stirring is continued. The product obtained by stirring is washed and dried. The concentration of the Tris solution is 8-12 mM. The mass ratio of the product to dopamine hydrochloride is 5-10:

1. The stirring time is 3-12 h.

4. A sodium-ion battery, characterized in that, The battery is a 2032 type button cell, and the nano-iron selenide assembled micron-scale material prepared by the preparation method described in any one of claims 1-3 is used as the negative electrode.

5. The sodium-ion battery as described in claim 4, characterized in that, The positive electrode of the sodium-ion battery is metallic sodium, and the separator is selected from polyolefin composite separators, glass fiber filter paper separators, or organic polymer nonwoven separators.

6. The sodium-ion battery as described in claim 4, characterized in that, The sodium salt in the electrolyte of the sodium-ion battery is selected from fluorine-containing sodium salts, boron-containing sodium salts, or other sodium salts; the solvent of the electrolyte is an ether solvent or an ester solvent, wherein the ether solvent is selected from ethylene glycol dimethyl ether or dioxolane; and the ester solvent is selected from propylene carbonate, ethylene carbonate, or diethyl carbonate.

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