A low-cost method for synthesizing CuSe at ambient pressure and low temperature and its application in sodium-ion batteries

Abstract

This invention belongs to the field of battery energy storage technology, and more specifically relates to a low-cost, low-temperature, ambient-pressure synthesis method for CuSe and its application in sodium-ion batteries. The invention uses copper and selenium sources as reactants, an acid solution as a promoter, and ethanol as a dispersant, and synthesizes the CuSe material via a wet process at ambient pressure and low temperature. The preparation method is simple and does not involve high temperature, high pressure, or toxic reagents, which are detrimental to practical applications. When used in sodium-ion batteries, it exhibits excellent cycle performance and rate capability.

Description

Technical Field

[0001] This invention belongs to the field of battery energy storage technology, and more specifically relates to a low-cost method for synthesizing CuSe at low temperature under normal pressure and its application in sodium-ion batteries. Background Technology

[0002] The intermittency of renewable energy sources such as solar and wind power, along with significant peak and valley fluctuations in energy supply, makes scalable, highly reliable, and low-cost stationary energy storage technologies a key constraint on their sustainable development. Sodium-ion battery energy storage technology has attracted widespread attention from researchers due to its advantages such as widely available and abundant raw materials, low cost, and higher safety, and it holds promise for meeting the application requirements of high cost-effectiveness and high safety in the new energy battery field.

[0003] The anode material is a key factor affecting the performance of sodium-ion batteries. However, because the radius of sodium ions (0.102 nm) is larger than that of lithium ions (0.076 nm), graphite, widely used in commercial lithium-ion batteries, cannot be directly used as an anode material for sodium-ion batteries. Therefore, it is urgent to find other suitable anode materials for sodium-ion batteries. Among anode materials, metal selenides, based on the sodium conversion storage mechanism, have high sodium storage specific capacity and good cycle stability, making them promising anode materials for sodium batteries. Among them, copper selenide has attracted widespread attention from researchers due to its high theoretical specific capacity and electronic conductivity.

[0004] Some existing technologies have successfully prepared self-assembled CuSe nanosheets with a columnar morphology (CPL-CuSe) using liquid-phase reduction and heat treatment. This method first prepares a Se prism precursor by reducing SeO2 with hydrazine hydrate, then reacts it with CuSO4 in a reduction system to form a Se@Cu3Se2 complex, and finally obtains cubic CuSe by heat treatment at 230℃.

[0005] Hexagonal CuSe nanosheets have been successfully synthesized via a one-step hydrothermal method in some existing technologies. This method uses CuCl2·H2O and Se powder as precursors to prepare h-CuSe nanosheets with a regular hexagonal morphology through a hydrothermal reaction under alkaline conditions.

[0006] Existing methods for preparing CuSe nanomaterials typically have significant limitations. For example, solvothermal / hydrothermal methods and high-temperature selenization methods often rely on high-temperature and high-pressure reaction conditions, requiring sophisticated equipment and consuming substantial energy. Furthermore, many methods require the use of hazardous or toxic chemicals such as hydrazine hydrate and sodium borohydride as reducing agents, or the use of expensive sodium selenite as the selenium source. These factors lead to complex processes, questionable safety, and increased production costs, thus hindering their large-scale practical application. Summary of the Invention

[0007] The purpose of this invention is to provide a low-cost method for synthesizing CuSe at low temperature under normal pressure and its application in sodium-ion batteries, so as to solve the problems existing in the prior art and realize the low-cost synthesis of CuSe at low temperature under normal pressure.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] One of the technical solutions of this invention is to provide a method for preparing CuSe, comprising the following steps:

[0010] The CuSe was obtained by wet synthesis using copper and selenium sources as reactants, acid solution as a promoter, and ethanol as a dispersant.

[0011] Furthermore, the copper source includes copper powder, copper foil, or copper mesh.

[0012] Furthermore, the selenium source includes selenium powder.

[0013] Furthermore, the acid solution includes hydrochloric acid, sulfuric acid, or nitric acid, with a concentration of 0.5-6 mol / L.

[0014] Furthermore, the ratio of the selenium source, acid solution, and ethanol is 0.1-3 mmol:4 mL:200 μL.

[0015] Furthermore, the molar ratio of the copper source to the selenium source is 1:1.

[0016] Furthermore, the wet synthesis reaction is carried out at a temperature of 40-100 °C for 2-10 days.

[0017] In this invention, the acid solution can promote the formation of copper ions from the copper source. The copper ions react with copper particles and Se to form copper selenide. Due to the hydrophobicity of selenium powder, it is difficult to disperse in the solution. The action of ethanol enables the selenium powder to be well dispersed in the solution.

[0018] The second technical solution of the present invention provides a CuSe prepared by the above preparation method, wherein the CuSe has a porous, wrinkled, blocky morphology.

[0019] The third technical solution of the present invention provides an electrode, wherein the active component of the electrode includes the above-mentioned CuSe.

[0020] The fourth technical solution of the present invention provides an application of the above-mentioned CuSe or the above-mentioned electrode in the preparation of sodium-ion batteries.

[0021] Fifth technical solution of the present invention: A sodium-ion battery is provided, wherein the sodium-ion battery uses the above-mentioned electrode as the negative electrode.

[0022] The present invention discloses the following technical effects:

[0023] This invention provides a method for preparing CuSe nano-anode materials for sodium-ion batteries under low-temperature and ambient-pressure conditions. This method achieves a mild, one-step wet chemical synthesis of pure-phase CuSe at low temperature and ambient pressure by mixing a copper source, a Se source, and an acid in solution at 40-100°C. When used as an anode material for sodium-ion batteries, this material exhibits high efficiency at 5.0 A g / L. –1 The discharge specific capacity still remains at 279.1 mAh g after 2000 cycles. –1 ; at 10.0 A g –1 After 2000 cycles, the discharge specific capacity still reaches 233.5 mAh g. –1 ; at 30 A g –1 Even at high current density, it still has 134.0 mAh g. –1 . Attached Figure Description

[0024] 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 undue limitation of the invention. In the drawings:

[0025] Figure 1 The image shows the XRD pattern of the CuSe material prepared in Example 1.

[0026] Figure 2 The XRD pattern of the composite material prepared in Comparative Example 1 is shown.

[0027] Figure 3 The XRD pattern of the composite material prepared in Comparative Example 2 is shown.

[0028] Figure 4 The image shows the XRD pattern of the composite material prepared in Comparative Example 3.

[0029] Figure 5 The images shown are SEM images of the CuSe material prepared in Example 1, where (a) and (b) are SEM images at different magnifications.

[0030] Figure 6 The graph shows the cycling performance of the CuSe material prepared in Example 1 at 5.0 A / g.

[0031] Figure 7 The graph shows the cycling performance of the CuSe material prepared in Example 1 at 10.0 A / g.

[0032] Figure 8 The graph shows the rate performance of the CuSe material prepared in Example 1. Detailed Implementation

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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 readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0037] 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.

[0038] Unless otherwise specified, all raw materials and reagents involved in the specific embodiments of this invention are commercially available products.

[0039] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.

[0040] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0041] Example 1

[0042] The preparation steps for low-cost, low-temperature synthesis of CuSe under ambient pressure include:

[0043] Add 1 mmol of copper powder and 1 mmol of selenium powder to a centrifuge tube containing 4 mL of 1 mol / L hydrochloric acid, mix well, then add 200 μL of ethanol, sonicate for 5 min to better disperse the selenium powder, then seal the centrifuge tube, place it in a 70℃ forced-air drying oven and let it stand for 3 days, then wash it with water by vacuum filtration to obtain CuSe material.

[0044] Example 2

[0045] The preparation steps for low-cost, low-temperature synthesis of CuSe under ambient pressure include:

[0046] Add 1 mmol of copper powder and 1 mmol of selenium powder to a centrifuge tube containing 4 mL of 2 mol / L hydrochloric acid, mix well, then add 200 μL of ethanol, sonicate for 5 min to better disperse the selenium powder, then seal the centrifuge tube and place it in a 70℃ forced-air drying oven for 3 days. After washing with water by vacuum filtration, the CuSe material is obtained.

[0047] Example 3

[0048] The preparation steps for low-cost, low-temperature synthesis of CuSe under ambient pressure include:

[0049] 1 mmol copper powder and 1 mmol selenium powder were added to a centrifuge tube containing 4 mL of 2 mol / L hydrochloric acid and mixed thoroughly. Then, 200 μL of ethanol was added and the mixture was sonicated for 5 min to better disperse the selenium powder. The centrifuge tube was then sealed and placed in a 70℃ forced-air drying oven for 5 days. After washing with water by vacuum filtration, CuSe material was obtained.

[0050] Example 4

[0051] The preparation steps for low-cost, low-temperature synthesis of CuSe under ambient pressure include:

[0052] 1 mmol copper powder and 1 mmol selenium powder were added to a centrifuge tube containing 4 mL of 1 mol / L hydrochloric acid and mixed thoroughly. Then, 200 μL of ethanol was added and the mixture was sonicated for 5 min to better disperse the selenium powder. The centrifuge tube was then sealed and placed in a 90℃ forced-air drying oven for 3 days. After washing with water by vacuum filtration, CuSe material was obtained.

[0053] Comparative Example 1

[0054] Add 1 mmol of copper powder and 1 mmol of selenium powder to a centrifuge tube containing 4 mL of water, mix well, then add 200 μL of ethanol, and sonicate for 5 min to better disperse the selenium powder. Seal the centrifuge tube and place it in a 90℃ drying oven for 3 days. After washing with water by vacuum filtration, obtain Cu, Se, Cu3Se2, and Cu.2-x Se composite materials.

[0055] Comparative Example 2

[0056] 1 mmol of copper powder and 1.5 mmol of selenium powder were added to a centrifuge tube containing 4 mL of 1 mol / L hydrochloric acid and mixed thoroughly. Then, 200 μL of ethanol was added and the mixture was sonicated for 5 min to better disperse the selenium powder. The centrifuge tube was then sealed and placed in a 90℃ forced-air drying oven for 3 days. After washing with water by vacuum filtration, a composite material of CuSe and Se was obtained.

[0057] Comparative Example 3

[0058] 1.5 mmol of copper powder and 1 mmol of selenium powder were added to a centrifuge tube containing 4 mL of 1 mol / L hydrochloric acid and mixed thoroughly. Then, 200 μL of ethanol was added, and the mixture was sonicated for 5 min to improve the dispersion of the selenium powder. The centrifuge tube was then sealed and placed in a 90℃ drying oven for 3 days. After washing with water by vacuum filtration, Cu3Se2 and Cu were obtained. 0.87 Se composite materials.

[0059] Test case

[0060] Figure 1 The image shows the XRD pattern of the CuSe material prepared in Example 1. As can be seen from the image, pure CuSe can be obtained when the molar ratio of Cu to Se is 1:1 and under acidic conditions.

[0061] Figure 2 The image shows the XRD pattern of the composite material prepared in Comparative Example 1. As can be seen from the figure, even with a Cu to Se molar ratio of 1:1, the lack of acidic conditions prevents the formation of pure CuSe; instead, only Cu, Se, Cu3Se2, and Cu are obtained. 2-x Complex products of Se.

[0062] Figure 3 The image shows the XRD pattern of the composite material prepared in Comparative Example 2. As can be seen from the image, when the proportion of Se is relatively high, the obtained sample contains excess Se in addition to CuSe, and the product is not a pure CuSe phase.

[0063] Figure 4 The image shows the XRD pattern of the composite material prepared in Comparative Example 3. As can be seen from the figure, when the proportion of Cu is relatively high, due to the variable valence properties of copper, the resulting sample is no longer CuSe, but rather forms Cu3Se2 and Cu... 0.87 Se.

[0064] Figure 5The images show SEM images of the material prepared in Example 1, where (a) and (b) are SEM images at different magnifications. As can be seen from the images, the morphology of the prepared CuSe material is a porous, wrinkled, blocky structure.

[0065] The materials prepared in Examples 1-4 and Comparative Examples 1-3 were used as active materials to prepare sodium-ion battery anodes. The steps included:

[0066] Working electrodes were prepared by mixing the active material with acetylene black, sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) in a mass ratio of 8:1:0.5:0.5. The slurry was coated onto copper foil and dried, with each electrode having an active material loading of 1.0 mg / cm³. -2 .

[0067] The negative electrode prepared above is used to assemble a sodium-ion battery. The steps include:

[0068] Half-cell assembly was performed in a glove box under an argon atmosphere. In the half-cell, metallic Na was used as the counter electrode, a glass fiber membrane (Whatman GF / F) was used as the separator, and 1 M NaPF6 dissolved in ethylene glycol dimethyl ether (MDE) was used as the electrolyte to assemble a 2032 type button cell.

[0069] The cycle performance and rate performance of the prepared batteries were tested using the following methods:

[0070] Cyclic performance: The CuSe electrode was subjected to cycling performance tests at 5.0 A / g and 10.0 A / g to investigate its excellent cycling stability.

[0071] Rate performance: CuSe electrodes were tested at rates ranging from 0.1 to 30.0 A / g to investigate their rate performance.

[0072] Figure 6 The graph shows the cycling performance of the CuSe material prepared in Example 1 at 5.0 A / g. As can be seen from the graph, the CuSe material exhibits excellent cycling stability, maintaining a capacity of 279.1 mAh g after 2000 cycles at 5.0 A / g. –1 This indicates that the material prepared by the low-cost, ambient-pressure, low-temperature method combines cost advantages with excellent cycling performance, and has potential for commercial application.

[0073] Figure 7 The graph shows the cycling performance of the CuSe material prepared in Example 1 at 10.0 A / g. As can be seen from the graph, the CuSe material still exhibits excellent cycling stability under ultra-high current, maintaining stable cycling performance for 2000 cycles at 10.0 A / g with a remaining capacity of 233.5 mAh g. –1This indicates that the material prepared by the low-cost, ambient-pressure, low-temperature method combines cost advantages with excellent cycling performance, and has potential for commercial application.

[0074] Figure 8 The figure shows the rate performance of the CuSe material prepared in Example 1. As can be seen from the figure, the prepared CuSe material exhibits excellent rate performance at 30 A g. –1 Even at high current density, it still has 134.0 mAh g. –1 This study confirms the feasibility of the atmospheric pressure and low temperature synthesis strategy. This method not only reduces the preparation cost but also endows the material with excellent rate adaptability, laying the foundation for its commercialization.

[0075] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0076] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing CuSe, characterized in that the steps include... include: The CuSe was obtained by a wet synthesis reaction using copper and selenium sources as reactants, acid solution as a promoter, and ethanol as a dispersant. The molar ratio of the copper source to the selenium source is 1:1; The copper source includes copper powder, copper foil, or copper mesh; The selenium source includes selenium powder; The acid solution includes hydrochloric acid, sulfuric acid, or nitric acid, with a concentration of 0.5-6 mol / L; The ratio of selenium source, acid solution, and ethanol is 0.1-3 mmol:4 mL:200 μL; The wet synthesis reaction is carried out at a temperature of 40-100 °C for 2-10 days.

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