Carbon sphere coated multi-sphere nickel-molybdenum bimetallic selenide composite material and preparation method thereof
By preparing a three-dimensional nanosphere structure of carbon spheres coated with multi-sphere nickel-molybdenum bimetallic selenide composite material, the problem of poor conductivity of MoSe2 was solved, and excellent cycle stability and rate performance of sodium-ion batteries were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QILU UNIVERSITY OF TECHNOLOGY (SHANDONG ACADEMY OF SCIENCES)
- Filing Date
- 2023-12-04
- Publication Date
- 2026-05-29
Smart Images
Figure CN117542983B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of sodium-ion battery anode materials, and relates to carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite materials and their preparation methods. 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] Metal selenides possess excellent reversibility and relatively small volume changes, exhibit superior electronic conductivity compared to metal sulfides and metal oxides, and are also cost-effective, have high specific capacity, can undergo abundant redox reactions, and demonstrate high thermal and mechanical stability. MoSe2, in particular, possesses a unique layered structure, with internal layers connected by covalent bonds and interlayers attracted by van der Waals forces, similar to graphite. Compared to graphite, MoSe2 has a larger interlayer spacing (approximately 0.65 nm), making it highly suitable for ion insertion and extraction, and is considered a promising sodium storage material.
[0004] However, the inventors discovered that MoSe2 has poor conductivity. For example, patent CN113036102B prepared molybdenum selenide, which had a conductivity of 1.0 Ag. -1 At a current density of only 118 mAh g -1 Its capacity is relatively low, and its specific capacity cannot meet the requirements of sodium-ion batteries. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material and its preparation method. Using the composite material provided by the present invention as the negative electrode material for sodium-ion batteries, the prepared sodium-ion batteries exhibit excellent cycle stability and rate performance.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows:
[0007] On the one hand, there is a carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material. The composite material is a three-dimensional nanosphere structure formed by a shell covering several cores. There are gaps between the cores and between the shell and the cores. The cores are nickel-molybdenum bimetallic selenides, and the shell is carbon.
[0008] In the composite material provided by this invention, the nickel-molybdenum bimetallic selenide anode material exhibits enhanced activity due to the synergistic effect between the two metals, which is more conducive to electrochemical reactions. Secondly, the large voids between the multinuclear particles and between the core and shell effectively buffer and adapt to volume changes, while providing rapid ion and electron transport channels. The nanomaterials increase the specific surface area, providing abundant reaction sites. Thirdly, the large voids between the core and shell alleviate volume expansion while reducing self-aggregation of the electrode material, thus improving conductivity to a certain extent and facilitating charge transfer. Therefore, the nanocomposite material provided by this invention combines the above advantages and accelerates the reaction kinetics of sodium-ion batteries, exhibiting excellent cycle stability and rate performance.
[0009] On the other hand, a method for preparing the above-mentioned carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material includes the following steps:
[0010] Divalent nickel salt, hexavalent molybdenum salt, trimesic acid, polyvinylpyrrolidone, thioacetamide, and hexamethylenetetramine were added to an organic solvent in a mass ratio of 8–10:8–10:14–16:19–21:4–6:19–21. The mixture was then subjected to a solvothermal reaction at 160–200 °C to obtain a nickel-molybdenum bimetallic organic framework (NiMo-MOF) nanosphere precursor. The polyvinylpyrrolidone had a weight-average molecular weight (Wt) of 55,000–60,000.
[0011] NiMo-MOF nanosphere precursors and selenium powder are heated to 450–650 °C for selenization treatment under a mixed atmosphere of inertness and reduction to obtain the desired product.
[0012] This invention uses divalent nickel salt, hexavalent molybdenum salt, and trimesic acid as raw materials to form NiMo-MOF. By adding polyvinylpyrrolidone with a wt% of 55,000–60,000, a multi-core-shell structured nickel-molybdenum bimetallic organic framework nanospheres is formed. Furthermore, the addition of hexamethylenetetramine facilitates the hydrolysis of thioacetamide to acetamide under alkaline conditions, thus aiding in the formation of the multi-core-shell structured nickel-molybdenum bimetallic organic framework nanospheres. Subsequently, selenization is performed under a mixed inert and reducing atmosphere to form a carbon-coated multi-sphere nickel-molybdenum bimetallic selenide composite material. Simultaneously, the in-situ carbon coating derived from the metal-organic framework precursor alleviates volume expansion and reduces self-aggregation of the electrode material, thereby improving conductivity to some extent and facilitating charge transfer.
[0013] Thirdly, the application of the aforementioned carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material in the preparation of sodium-ion battery anodes.
[0014] Fourthly, an ion battery, wherein the ion battery is a sodium-ion battery, and the active material in the negative electrode of the sodium-ion battery is the aforementioned carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material.
[0015] The beneficial effects of this invention are as follows:
[0016] The carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material provided by this invention offers abundant redox reaction sites through the synergy of the bimetals. The in-situ derived carbon shell coating of the precursor increases the specific surface area and lattice spacing, which to some extent accelerates the transport rate of ions and electrons and reduces the agglomeration of electrode materials. The bimetallic selenide composite material synergistically leverages the advantages of each component. Most importantly, the multi-core-shell structure can effectively suppress volume expansion and structural collapse, which is beneficial to the stability of the electrode material structure. When applied to sodium-ion battery anode materials, it exhibits excellent cycle stability and rate performance. Attached Figure Description
[0017] 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.
[0018] Figure 1 The images shown are scanning electron microscope (SEM) images of the multi-core-shell structured NiMo-MOF nanosphere precursor (polyvinylpyrrolidone molecular weight Wt = 58000) prepared in Example 1 of this invention, where Figure a is a low-magnification SEM image and Figure b is a high-magnification SEM image.
[0019] Figure 2 The images shown are transmission electron microscope (TEM) images of the multi-core-shell structured NiMo-MOF nanosphere precursor (polyvinylpyrrolidone molecular weight Wt = 58000) prepared in Example 1 of this invention, where Figure a is a high-magnification TEM image and Figure b is a low-magnification TEM image.
[0020] Figure 3 The images shown are scanning electron microscope (SEM) images of the multi-core-shell structured NiMo-MOF nanosphere precursor (polyvinylpyrrolidone molecular weight Wt = 10000) prepared in Example 2 of this invention, where Figure a is a low-magnification SEM image and Figure b is a high-magnification SEM image.
[0021] Figure 4 The images shown are scanning electron microscope (SEM) images of the multi-core-shell structured NiMo-MOF nanosphere precursor (polyvinylpyrrolidone with a molecular weight Wt = 40000) prepared in Example 3 of this invention, where Figure a is a high-magnification SEM image and Figure b is a low-magnification SEM image.
[0022] Figure 5The X-ray diffraction (XRD) pattern of the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material prepared in Example 4 of the present invention;
[0023] Figure 6 The images shown are scanning electron microscope (SEM) images of the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material prepared in Example 4 of the present invention, wherein Figure a is a low-magnification SEM image and Figure b is a high-magnification SEM image.
[0024] Figure 7 The images shown are transmission electron microscope (TEM) images of the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material prepared in Example 4 of the present invention, wherein Figure a is a low-magnification TEM image and Figure b is a high-magnification TEM image.
[0025] Figure 8 The carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material prepared in Example 4 of this invention was used as a sodium electrode at 1.0 Ag. -1 Cyclic performance at current density;
[0026] Figure 9 The carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material prepared in Example 4 of this invention has a content of 0.1–5.0 Ag. -1 Rate performance diagram at current density. Detailed Implementation
[0027] 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.
[0028] 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.
[0029] Given that MoSe2 has poor conductivity and low specific capacity as a sodium-ion battery, which is difficult to meet the requirements of sodium-ion batteries, this invention proposes a carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material and its preparation method.
[0030] In a typical embodiment of the present invention, a carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material is provided. The composite material is a three-dimensional nanosphere structure formed by an outer shell covering several cores. There are gaps between the cores and between the outer shell and the cores. The cores are nickel-molybdenum bimetallic selenides, and the outer shell is carbon.
[0031] This invention effectively suppresses volume expansion and structural collapse through the synergistic effect of nickel-molybdenum bimetallic selenide and the influence of microstructure, which is beneficial to the stability of electrode material structure. When applied to sodium-ion battery anode materials, it exhibits excellent cycle stability and rate performance.
[0032] In some embodiments, the nickel-molybdenum bimetallic selenide comprises NiSe and MoSe2.
[0033] In some embodiments, the diameter of the nanospheres is 400–500 nm.
[0034] In some embodiments, the thickness of the outer shell is 40–50 nm.
[0035] In some embodiments, the diameter of the core is no greater than 80 nm.
[0036] Another embodiment of the present invention provides a method for preparing the above-mentioned carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material, comprising the following steps:
[0037] Divalent nickel salt, hexavalent molybdenum salt, trimesic acid, polyvinylpyrrolidone, thioacetamide, and hexamethylenetetramine were added to an organic solvent in a mass ratio of 8–10:8–10:14–16:19–21:4–6:19–21. The mixture was then subjected to a solvothermal reaction at 160–200 °C to obtain a NiMo-MOF nanosphere precursor. The polyvinylpyrrolidone had a weight-average molecular weight of 55,000–60,000.
[0038] NiMo-MOF nanosphere precursors and selenium powder are heated to 450–650 °C under a mixed atmosphere of inertness and reduction to undergo selenization treatment, thus obtaining the desired product.
[0039] This invention selects raw materials and controls the particle size of nickel-molybdenum bimetallic organic framework nanospheres through a solvothermal method. After selenization annealing, selenides are obtained, and a carbon shell derived in situ from the precursor is formed, which stabilizes the electrode structure and prevents self-aggregation and electrode pulverization, thereby improving sodium storage performance.
[0040] The divalent nickel salts described in this invention are compounds containing divalent nickel ions, such as nickel dichloride, nickel nitrate, nickel acetylacetone, nickel sulfate, and nickel acetate.
[0041] The hexavalent molybdenum salt described in this invention is a compound containing hexavalent molybdenum ions, such as ammonium molybdate, molybdenum acetylacetonate, sodium molybdate, etc.
[0042] The solvothermal method described in this invention is a reaction method that uses an organic solvent as a solvent in a closed container and generates high temperature and high pressure conditions after heating.
[0043] In some embodiments, the organic solvent used in the solvothermal method is N,N-dimethylformamide. Studies have shown that using this organic solvent results in better coordination reactions.
[0044] In some embodiments, the reaction time is 12 to 36 hours.
[0045] In some embodiments, the volume fraction of the reducing gas in the mixed atmosphere is 5-10%. The reducing gas is hydrogen, CO, etc. When hydrogen is used as the reducing gas, the obtained material properties are better.
[0046] In some embodiments, a tube furnace is used for selenization treatment. Using a tube furnace allows selenium powder and nickel-molybdenum bimetallic organic framework nanosphere precursors to be placed upstream and downstream of the furnace, heated to a set temperature at a controlled rate, held at that temperature, and then cooled at a controlled rate.
[0047] In some embodiments, the mass ratio of selenium powder to NiMo-MOF nanosphere precursor is 1:1 to 5; preferably 1:3.
[0048] In some embodiments, the selenization treatment temperature is 520–560°C.
[0049] In some embodiments, during the selenization treatment, the heating rate is 1–5 °C / min; preferably 3.5–4.0 °C / min.
[0050] In some embodiments, the selenization treatment time is 2 to 8 hours; preferably 3.5 to 4.5 hours. The selenization treatment time described in this invention refers to the time spent holding the temperature after heating to a set temperature, excluding the heating and cooling times.
[0051] A third embodiment of the present invention provides an application of the above-mentioned carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material in the preparation of a sodium-ion battery anode.
[0052] Specifically, the battery negative electrode is generally formed by mixing an active material, a conductive material (e.g., acetylene black, graphene, etc.), and a binder material (e.g., polyvinylidene fluoride, carboxymethyl cellulose, etc.) with a solvent to form a slurry, which is then coated onto a current collector and dried. In this invention, the active material is the aforementioned carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material. This battery negative electrode can be used to prepare sodium-ion batteries.
[0053] In a fourth embodiment of the present invention, an ion battery is provided, wherein the ion battery is a sodium ion battery, and the active material in the negative electrode of the sodium ion battery is the above-mentioned carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material.
[0054] Specifically, the ion battery consists of a positive electrode, a separator, an electrolyte, and a negative electrode. The positive electrode is a sodium sheet, and the electrolyte is an electrolyte containing sodium ions (e.g., NaPF6, NaClO4, etc.).
[0055] 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.
[0056] Example 1
[0057] A method for preparing a precursor of multi-core-shell structured nickel-molybdenum bimetallic organic framework nanospheres includes the following steps:
[0058] 9 mg of nickel acetylacetonate, 15 mg of trimesic acid, 20 mg of polyvinylpyrrolidone (molecular weight Wt = 58000), 5 mg of thioacetamide, 9 mg of ammonium molybdate tetrahydrate, and 20 mg of hexamethylenetetramine were dissolved in 10 mL of N,N-dimethylformamide. After stirring evenly, the reaction solution was transferred to a 25 mL Teflon-lined stainless steel autoclave and heated at 180 °C for 24 hours. After washing three times each with deionized water and anhydrous ethanol by centrifugation, the mixture was dried in a vacuum drying oven at 65 °C for 4 hours to obtain a multi-core-shell structured NiMo-MOF nanosphere precursor.
[0059] The scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the multi-core-shell structured nickel-molybdenum bimetallic organic framework nanosphere composite material prepared in this embodiment are shown below. Figure 1 and Figure 2 As shown, from Figure 1 As can be seen, the obtained nickel-molybdenum bimetallic organic framework nanosphere composite material is spherical with a diameter of about 500 nm. Figure 2 It can be seen that there are small spheres with a diameter of about 50 nm distributed inside the sphere.
[0060] Example 2
[0061] A method for preparing a nickel-molybdenum bimetallic organic framework nanosphere precursor is as described in Example 1, except that polyvinylpyrrolidone (molecular weight Wt = 58000) is replaced with polyvinylpyrrolidone (molecular weight Wt = 10000).
[0062] The scanning electron microscope image of the NiMo-MOF nanosphere precursor prepared in this embodiment is shown below. Figure 3 As shown, from Figure 3 As can be seen, the diameter of the obtained NiMo-MOF nanospheres is about 50 nm, and they are not covered by a shell.
[0063] Example 3
[0064] A method for preparing NiMo-MOF nanosphere precursor is as described in Example 1, except that: vinylpyrrolidone (molecular weight Wt = 58000) is replaced with polyvinylpyrrolidone (molecular weight Wt = 40000).
[0065] The scanning electron microscope (SEM) image of the NiMo-MOF nanospheres prepared in this embodiment is shown below. Figure 4 As shown, from Figure 4 As can be seen, most of the obtained NiMo-MOF nanospheres are small spheres with a diameter of 50 nm, and a small number of spheres with a diameter of about 500 nm, and these large spheres encapsulate the small spheres.
[0066] Example 4
[0067] The preparation of carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material includes the following process steps:
[0068] Selenization of a multi-core-shell NiMo-MOF nanosphere precursor (polyvinylpyrrolidone molecular weight Wt = 58000) was performed in a tube furnace. Selenium powder (150 mg) and the precursor (50 mg) were placed upstream and downstream of a ceramic boat, respectively. Under an Ar / H2 atmosphere (Ar to H2 volume ratio 95:5), the tube furnace was gradually heated (2 °C / min) to 550 °C and held for 4 hours. The resulting black powder was the nickel-molybdenum bimetallic selenide composite material. Its X-ray diffraction (XRD) pattern is shown below. Figure 5 Its main components are NiSe and MoSe2. Figure 6 and Figure 7 The images show scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the multi-sphere nickel-molybdenum bimetallic selenide composite material coated in carbon spheres. It can be observed that the morphology after selenization is basically consistent with that of the precursor.
[0069] Electrochemical performance testing:
[0070] The multi-sphere nickel-molybdenum bimetallic selenide composite material coated in carbon spheres obtained in this embodiment is used as a negative electrode material for sodium-ion batteries. The negative electrode material, acetylene black, and sodium carboxymethyl cellulose are added to secondary water at a mass ratio of 7:2:1 and ball-milled for 6 hours. Then, it is coated on copper foil, vacuum dried, and cut into negative electrode sheets with a diameter of 12 mm.
[0071] The sodium-ion battery was assembled using a self-made sodium sheet as the positive electrode, glass fiber (Whatman GF / F) as the separator, and NaPF6 as the main electrolyte component. At 1.0 Ag... -1 The material exhibits excellent cycling performance, with a specific capacity of 269.8 mAh g after 2800 cycles. -1 ,See Figure 8Material rate performance testing was conducted at Ag ratios of 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, and 5.0. -1 At that time, its reversible specific capacities were 297.3, 246.1, 224.5, 204.6, 200.3, 190.2 and 180.5 mAh g, respectively. -1 ,See Figure 9 .
[0072] 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 a carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material, characterized in that, Includes the following steps: Divalent nickel salt, hexavalent molybdenum salt, trimesic acid, polyvinylpyrrolidone, thioacetamide, and hexamethylenetetramine were added to an organic solvent in a mass ratio of 8~10:8~10:14~16:19~21:4~6:19~21, and a complexation reaction was carried out using a solvothermal method at 160~200℃ to obtain a NiMo-MOF nanosphere precursor; the weight average molecular weight of the polyvinylpyrrolidone was 55000~60000. NiMo-MOF nanosphere precursor and selenium powder are heated to 450~650℃ under a mixed atmosphere of inertness and reduction to undergo selenization treatment, thus obtaining the product. The composite material is a three-dimensional nanosphere structure formed by an outer shell covering several cores. There are gaps between the cores and between the outer shell and the cores. The cores are nickel-molybdenum bimetallic selenides, and the outer shell is carbon.
2. The preparation method of the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material as described in claim 1, characterized in that, The nanospheres have a diameter of 400~500 nm; Alternatively, the thickness of the outer shell is 40~50 nm; Alternatively, the diameter of the core may not exceed 80 nm.
3. The preparation method of the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material as described in claim 1, characterized in that, The organic solvent used in the solvothermal method is N,N-dimethylformamide.
4. The preparation method of the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material as described in claim 1, characterized in that, The reaction time is 12-36 h.
5. The method for preparing the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material as described in claim 1, characterized in that, In the mixed atmosphere, the volume fraction of reducing gas is 5-10%.
6. The method for preparing the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material as described in claim 1, characterized in that, Selenization was performed using a tubular furnace.
7. The method for preparing the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material as described in claim 1, characterized in that, The mass ratio of selenium powder to NiMo-MOF nanosphere precursor is 1:1~5; Alternatively, the selenization treatment temperature is 520~560 ℃; Alternatively, during selenization treatment, the heating rate is 1~5 ℃ / min; Alternatively, the selenization treatment time is 2~8 hours.
8. The method for preparing the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material as described in claim 7, characterized in that, The mass ratio of selenium powder to NiMo-MOF nanosphere precursor is 1:
3.
9. The method for preparing the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material as described in claim 7, characterized in that, During selenization treatment, the heating rate is 3.5~4.0 ℃ / min.
10. The method for preparing the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material as described in claim 7, characterized in that, The selenization treatment time is 3.5~4.5 h.
11. The application of the carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material prepared by the method of claim 1 in the preparation of sodium-ion battery anodes.
12. An ion battery, wherein the ion battery is a sodium-ion battery, characterized in that, The active material in the negative electrode of the sodium-ion battery is a carbon sphere-coated multi-sphere nickel-molybdenum bimetallic selenide composite material prepared by the preparation method described in claim 1.