A MoTe2-MoN composite hard carbon material, its preparation method and application
By forming a MoTe2-MoN heterojunction in situ on a biomass hard carbon substrate, the problems of conductivity and volume change in sodium-ion battery anode materials were solved, achieving a high-efficiency performance improvement in sodium-ion batteries, simplifying the synthesis process and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUILIN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2026-03-17
- Publication Date
- 2026-06-09
Smart Images
Figure CN122166730A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of sodium-ion battery electrode material technology, and particularly relates to a MoTe2-MoN composite hard carbon material, its preparation method and application. Background Technology
[0002] Developing high-performance rechargeable energy storage batteries is of great significance for alleviating environmental pollution, meeting the needs of sustainable social development, and promoting the application of new energy sources. Among various energy storage systems, sodium-ion batteries (SIBs) have attracted widespread attention due to their abundant sodium resources, low cost, and potential for large capacity and long lifespan. However, due to the large radius of sodium ions, SIBs often exhibit slow kinetics in electrochemical processes, leading to severe challenges in their rate performance, long-cycle stability, and safety. To overcome these problems, researchers are committed to developing novel high-performance SIB anode materials. Currently, hard carbon anode materials, as one of the most promising anode materials for practical applications, can provide high capacities of 300-400 mAh / g, but their rate performance is poor and cannot meet the requirements of high-rate energy storage applications.
[0003] Transition metal dichalcogenides (TMDs) possess unique advantages such as layered structure and high theoretical capacity. In particular, the two-dimensional material MoTe2 exhibits weak van der Waals interactions between Te and Mo, which are more favorable for Na. + Diffusion. However, its poor conductivity and the resulting volume change and structural collapse during charge and discharge, leading to accelerated capacity decay, still exist. To address this issue, the most common strategy is to combine it with carbon materials. This can mitigate the volume change caused by sodium storage and improve the overall electrode cycle life. However, simply combining the two cannot fully realize its high capacity; therefore, designing heterostructures is an effective strategy to unleash the potential of composite materials. This is due to the ability to generate an internal electric field at the heterostructure interface to enhance the sodium... + The diffusion dynamics increase the density of states of the Fermi level, reduce the Na transport barrier, and enhance the capacity of the material.
[0004] As a typical transition metal nitride (TMN), MoN possesses a low ion migration barrier and high conductivity, effectively improving electron / ion transport. Therefore, constructing composite materials with heterostructures of MoN, MoTe2, and C shows potential as ideal anode materials. Previously reported methods for synthesizing MoN mainly include direct metal nitridation and sulfide ammonolysis. However, these methods typically involve harsh synthesis conditions, including toxic gases (NH3) and high-pressure environments, which are unfavorable for large-scale production and practical applications. Currently, there are no reports on the simple synthesis of nitrides and the construction of MoTe2-MoN heterojunction composite hard carbon materials for use as anodes in sodium-ion batteries. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention proposes a MoTe2-MoN composite hard carbon material, its preparation method, and its application. The MoTe2-MoN composite hard carbon material is applied to the anode material of sodium-ion batteries to promote the industrialization of sodium-ion batteries.
[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing MoTe2-MoN composite hard carbon material, comprising the following steps: (1) Dissolve ammonium molybdate in water and add ethylenediamine to obtain a mixture. Then add hydrochloric acid dropwise until a precipitate is formed. After heating the reaction, separate the solid and liquid, wash and dry to obtain MoO3-EDA nanorods. (2) The MoO3-EDA nanorods obtained in step (1) were ultrasonically dispersed in water, urea solution was added, and then biomass hard carbon was added. After mixing evenly, the mixture was dried to obtain the composite precursor. (3) The composite precursor obtained in step (2) and tellurium (Te) powder are calcined together in a reducing atmosphere at a temperature of 800°C to achieve in-situ co-generation and composite of MoTe2 and MoN on a biomass hard carbon substrate, forming a MoTe2-MoN heterojunction, and obtaining the MoTe2-MoN composite hard carbon material.
[0007] In the preparation method of the present invention, the composite precursor and tellurium powder are calcined together in a reducing atmosphere. Taking advantage of the synchronous decomposition characteristics of urea during the heat treatment process, it is used as both a nitrogen source and a reducing atmosphere precursor to drive a one-step coupling reaction between molybdenum oxide and Te vapor, thereby realizing the in-situ co-generation and composite of MoTe2 and MoN on a biomass hard carbon substrate to form a MoTe2-MoN heterojunction.
[0008] Further, in step (1), the mass ratio of ammonium molybdate to ethylenediamine is 1.28:1; and the concentration of hydrochloric acid is 1M.
[0009] Furthermore, in step (1), the reaction temperature of the heating reaction is 40-70℃ and the reaction time is 1-3h.
[0010] Further, in step (2), the mass ratio of the MoO3-EDA nanorods, urea in the urea solution, and biomass hard carbon is 0.1:(0.4-1):(0.2-0.4); preferably, the mass ratio of the MoO3-EDA nanorods, urea in the urea solution, and biomass hard carbon is 0.1:0.8:0.3.
[0011] Further, in step (3), the mass ratio of tellurium powder to biomass hard carbon is (0.1-0.4):(0.2-0.4); preferably, the mass ratio of tellurium powder to biomass hard carbon is 0.3:0.3.
[0012] Furthermore, in step (3), the calcination time is 3-7 h.
[0013] Further, in step (3), the reducing atmosphere includes hydrogen (H2) and argon (Ar); preferably, the reducing atmosphere includes 5% H2 + 95% Ar (% represents volume percentage).
[0014] Furthermore, in step (2), the ultrasonic dispersion time is 0.5-1.5 h.
[0015] Furthermore, in step (2), the biomass hard carbon is obtained by pretreating biomass raw materials with alkaline solution via hydrothermal treatment, followed by high-temperature carbonization. The specific preparation method is as follows: S1. Take biomass raw materials, wash and dry them to remove impurities, then cut them into pieces and put them into a polytetrafluoroethylene reactor. Pour 2.5 M KOH solution into it for hydrothermal reaction. After the reaction is completed, cool it to room temperature, take it out and filter it with deionized water until it is neutral. Place the product in an oven to dry. S2. Place the product from step S1 into a corundum crucible and send it into a tube furnace for carbonization to obtain biomass hard carbon.
[0016] Furthermore, in the preparation method S1 of the biomass hard carbon, the biomass raw material is sisal fiber, and the hydrothermal reaction temperature is 140-180℃; in S2, the carbonization temperature is 700-900℃, and the carbonization is carried out under a calcination protective gas, specifically argon (Ar).
[0017] The present invention also provides a MoTe2-MoN composite hard carbon material, which is prepared according to the above preparation method.
[0018] The present invention also provides an application of the above-mentioned MoTe2-MoN composite hard carbon material in the preparation of sodium-ion batteries, wherein the MoTe2-MoN composite hard carbon material serves as the negative electrode of the sodium-ion battery.
[0019] Compared with the prior art, the present invention has the following advantages and technical effects: (1) The preparation method of the present invention abandons the complex multi-step separation synthesis process and makes original use of the synchronous decomposition characteristics of urea in heat treatment, so that it can be used as both a nitrogen source and a reducing atmosphere precursor. Molybdenum oxide and Te vapor undergo a one-step coupling reaction, realizing the in-situ co-generation and composite of MoTe2 and MoN. This "killing three birds with one stone" design greatly simplifies the process and reduces energy consumption and cost.
[0020] (2) In the MoTe2-MoN composite hard carbon material prepared by the present invention, the MoTe2 nanoribbons and MoN nanosheets grow uniformly and interlaced on the carbon skeleton, forming a tightly connected heterogeneous interface. The built-in electric field induced by the heterogeneous interface accelerates the charge transport dynamics, improves the reaction rate, and enhances the cycle stability. Attached Figure Description
[0021] 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: Figure 1 The images show the XRD patterns of the composite hard carbon materials prepared in Example 1 and Comparative Examples 1-3, where 1 is Comparative Example 1, 2 is Comparative Example 2, 3 is Comparative Example 3, and 4 is Example 1. Figure 2 SEM image of the MoTe2-MoN composite hard carbon material prepared in Example 1; Figure 3 TEM images of the MoTe2-MoN composite hard carbon material prepared in Example 1 (a scale bar is 2 μm, b scale bar is 0.5 μm). Figure 4 SEM image of the molybdenum-based composite carbon material prepared in Comparative Example 1; Figure 5 SEM image of the molybdenum-based composite carbon material prepared in Comparative Example 2; Figure 6 SEM image of the molybdenum-based composite carbon material prepared in Comparative Example 3; Figure 7 The XRD pattern of the molybdenum-based composite carbon material prepared in Comparative Example 4; Figure 8 SEM image of the molybdenum-based composite carbon material prepared in Comparative Example 4; Figure 9 The first three CV curves of the MoTe2-MoN composite hard carbon material prepared in Example 1 at a scan rate of 0.5 mV / s; Figure 10 The capacitance contribution curve of the MoTe2-MoN composite hard carbon material prepared in Example 1 (scan rate of 0.8 mV / s). Figure 11 Cyclic performance of the MoTe2-MoN composite hard carbon material prepared in Example 1 and the carbon materials prepared in Comparative Examples 1-3 at a current density of 0.5 A / g (where 1 is Comparative Example 1, 2 is Comparative Example 2, 3 is Comparative Example 3, and 4 is Example 1). Figure 12The graph shows the cycling performance of the composite hard carbon material prepared for Comparative Example 4 at a current density of 0.5 A / g. Detailed Implementation
[0022] 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.
[0023] 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. Every smaller range between any stated value or intermediate value within a stated range, and 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.
[0024] 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.
[0025] 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 apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0026] 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.
[0027] This invention provides a method for preparing a MoTe2-MoN composite hard carbon material, comprising the following steps: (1) Dissolve ammonium molybdate in water and add ethylenediamine to obtain a mixture. Then add hydrochloric acid dropwise until a precipitate is formed. After heating the reaction, separate the solid and liquid, wash and dry to obtain MoO3-EDA nanorods. (2) The MoO3-EDA nanorods obtained in step (1) were ultrasonically dispersed in water, urea solution was added, and then biomass hard carbon was added. After mixing evenly, the mixture was dried to obtain the composite precursor. (3) The composite precursor obtained in step (2) and tellurium (Te) powder are calcined together in a reducing atmosphere at a temperature of 800°C to achieve in-situ co-generation and composite of MoTe2 and MoN on a biomass hard carbon substrate, forming a MoTe2-MoN heterojunction, and obtaining MoTe2-MoN composite hard carbon material.
[0028] In the preparation method of the present invention, the composite precursor and tellurium powder are calcined together in a reducing atmosphere. Taking advantage of the synchronous decomposition characteristics of urea during the heat treatment process, it is used as both a nitrogen source and a reducing atmosphere precursor to drive a one-step coupling reaction between molybdenum oxide and Te vapor, thereby realizing the in-situ co-generation and composite of MoTe2 and MoN on a biomass hard carbon substrate to form a MoTe2-MoN heterojunction.
[0029] More specifically, the preparation method of the MoTe2-MoN composite hard carbon material in this embodiment of the invention includes the following steps: S1. Sisal fibers are rubbed, washed, and dried to remove impurities. Then, they are cut into small pieces (1-2 cm) and placed in a polytetrafluoroethylene reactor. A 2.5 M KOH solution is poured into the reactor for hydrothermal reaction (hydrothermal temperature 140-180℃, hydrothermal time 14 h). After the reaction is completed, the mixture is cooled to room temperature, removed, and filtered and washed with deionized water until neutral. The product is then placed in an oven to dry and remove moisture. The dried sample is then placed in a crucible and calcined in a tube furnace (calcination atmosphere is Ar, calcination temperature is 700-900℃, calcination time is 1 h) to obtain sisal fiber carbon (TSFC). S2. Weigh out ammonium molybdate, dissolve it in water, and add ethylenediamine. Stir at room temperature to obtain a mixture (the mass ratio of ammonium molybdate to ethylenediamine is 1.28:1). Then, add 1 M hydrochloric acid solution dropwise to the above solution until a white precipitate appears. Place it in an oven at 40-70 ℃ and heat for 1-3 h (preferably in an oven at 50 ℃ for 2 h). After the reaction is complete, filter the product and wash it thoroughly with ethanol. Dry it in a drying oven at 60 ℃ to obtain MoO3-EDA nanorods. Weigh 0.1 g of MoO3-EDA nanorods and place them in beaker A. Add deionized water and sonicate for 0.5-1.5 h to disperse them evenly. Dissolve 0.8 g of urea in beaker B with deionized water. Place 0.2-0.4 g of sisal fiber carbon (preferably 0.3 g) in beaker C and add deionized water. Sonicate for 1 h to disperse the carbon. S3. Mix and stir the solutions in beakers A and B until they are evenly mixed. Then pour the mixture into beaker C and stir for 6 hours. After stirring, freeze-dry the sample for 24 hours. Place the obtained composite precursor powder downstream of a tube furnace and place 0.1-0.4 g of Te powder (preferably 0.3 g) upstream. Calcinate the powder together at 800℃ for 3-7 hours (preferably 5 hours). The calcination gas is 5% H2 + 95% Ar. After calcination, allow the mixture to cool naturally. The resulting black powder is the MoTe2-MoN composite hard carbon material.
[0030] This invention also provides a MoTe2-MoN composite hard carbon material, which is prepared according to the above preparation method.
[0031] This invention also provides an application of the above-mentioned MoTe2-MoN composite hard carbon material in the preparation of sodium-ion batteries, specifically as a negative electrode of sodium-ion batteries.
[0032] In this embodiment of the invention, room temperature refers to "25±3℃".
[0033] The technical solution of the present invention will be further illustrated by the following embodiments.
[0034] Example 1 A method for preparing a MoTe2-MoN composite hard carbon material includes the following steps: S1. Sisal fibers are rubbed, washed, and dried to remove impurities. Then, they are cut into small pieces (1-2 cm) and placed in a polytetrafluoroethylene reactor. A 2.5 M KOH solution is poured into the reactor for hydrothermal reaction (hydrothermal temperature 160℃, hydrothermal time 14 h). After the reaction is completed, the mixture is cooled to room temperature, removed, and filtered and washed with deionized water until neutral. The product is then placed in an oven to dry and remove moisture. The dried sample is then placed in a crucible and calcined in a tube furnace (calcination atmosphere Ar, calcination temperature 800℃, calcination time 1 h) to obtain sisal fiber carbon (TSFC). S2. Weigh 1.28 g of ammonium molybdate and dissolve it in 15 mL of water. Add 1 g of ethylenediamine and stir at room temperature to obtain a mixture. Then, add 1M hydrochloric acid solution dropwise to the above solution until a white precipitate appears. Place it in a 50℃ oven and heat for 2 h. After the reaction is complete, filter the product and wash it thoroughly with ethanol. Dry it in a 60℃ drying oven to obtain MoO3-EDA nanorods. Weigh 0.1 g of MoO3-EDA nanorods and place them in beaker A. Add 15 mL of deionized water and sonicate for 1 h to disperse them evenly. Dissolve 0.8 g of urea in 10 mL of deionized water in beaker B. Place 0.3 g of sisal fiber carbon in beaker C and add 20 mL of deionized water. Sonicate for 1 h to disperse the carbon. S3. Mix and stir the solutions in beakers A and B until they are evenly mixed. Then pour the mixture into beaker C and stir for 6 hours. After stirring, freeze-dry the sample for 24 hours. Place the obtained composite precursor powder in the downstream of a tube furnace and place 0.3g of Te powder in the upstream. Calcinate the powder together at 800℃ for 5 hours. The atmosphere during calcination is 5% H2 + 95% Ar (volume concentration). After calcination, allow the powder to cool naturally. The resulting black powder is the MoTe2-MoN composite hard carbon material.
[0035] The XRD pattern of the MoTe2-MoN composite hard carbon material prepared in Example 1 is shown in [reference needed]. Figure 1 Figure 4 shows that not only are there diffraction peaks for MoTe2, but also for MoN, located near 31.9°, 36.2°, and 49.0°. This indicates that at this temperature, the NH3 from urea decomposition nitrids a portion of the molybdenum source in situ to generate MoN.
[0036] The scanning electron microscope (SEM) image of the MoTe2-MoN composite hard carbon material prepared in Example 1 is shown below. Figure 2 It can be seen that not only nanoribbons but also hexagonal nanosheets were observed on the sisal fiber carbon. The nanoribbons were less than 10 nm thick and 30–70 nm wide, while the hexagonal nanosheets were approximately 200 nm thick. This indicates that the MoTe2-MoN / C heterojunction composite material was successfully prepared at this temperature.
[0037] Figure 3 The TEM images (a scale bar is 2 μm, b scale bar is 0.5 μm) of the MoTe2-MoN composite hard carbon material prepared in Example 1 clearly show the growth of the two materials on sisal fiber carbon, consistent with SEM.
[0038] Comparative Example 1 Same as Example 1, except that the calcination temperature in step S3 is 500°C, and the black powder obtained after natural cooling is a molybdenum-based composite carbon material.
[0039] The XRD pattern of the molybdenum-based composite carbon material prepared in Comparative Example 1 is shown in Figure 1. Figure 1 As shown in Figure 1, the intensity of the diffraction peaks of MoTe2 is relatively weak, indicating that the upstream Te powder sublimates and produces Te vapor after being heated to a certain degree at this temperature. However, due to the low synthesis temperature, the reaction is incomplete, resulting in low crystallinity of the product.
[0040] The scanning electron microscope (SEM) image of the molybdenum-based composite carbon material prepared in Comparative Example 1 is shown below. Figure 4 As can be seen, MoTe2 nanosheets can be grown on the carbon matrix of sisal fibers, a result that corresponds to the XRD pattern.
[0041] Comparative Example 2 Same as Example 1, except that the calcination temperature in step S3 is 600°C, and the black powder obtained after natural cooling is a molybdenum-based composite carbon material.
[0042] The XRD pattern of the molybdenum-based composite carbon material prepared in Comparative Example 2 is shown in Figure 2. Figure 1 As shown in Figure 2, the diffraction peak intensity of MoTe2 is enhanced, with significant enhancements at positions such as 12.8°, 25.8°, and 32.2°, indicating that MoTe2 can be synthesized at this temperature.
[0043] The scanning electron microscope (SEM) image of the molybdenum-based composite carbon material prepared in Comparative Example 2 is shown below. Figure 5 It can be seen that the nanosheets on the sisal fiber carbon are widened, the crystallinity is higher and the grain size is larger at this temperature, and this result corresponds to the XRD pattern.
[0044] Comparative Example 3 Same as Example 1, except that the calcination temperature in step S3 is 700°C, and the black powder obtained after natural cooling is a molybdenum-based composite carbon material.
[0045] The XRD pattern of the molybdenum-based composite carbon material prepared in Comparative Example 3 is shown in Figure 3. Figure 1 As shown in Figure 3, the diffraction peak intensity of MoTe2 is further enhanced, indicating that the growth of MoTe2 is further promoted with the assistance of reducing agents (cisal fiber carbon, NH3 and H2 from urea decomposition). MoTe2 can be completely synthesized at this temperature.
[0046] The scanning electron microscope (SEM) image of the molybdenum-based composite carbon material prepared in Comparative Example 3 is shown below. Figure 6 It can be seen that an increase in nanosheets can be observed on sisal fiber carbon, and the growth of the material can be further promoted at this temperature.
[0047] Comparative Example 4 Same as Example 1, except that urea is not added in step S2 (to verify the key role of urea as a nitrogen source and a precursor for reducing atmosphere).
[0048] The XRD pattern of the molybdenum-based composite carbon material prepared in Comparative Example 4 is shown in Figure 4. Figure 7 It can be seen that obvious MoTe2 diffraction peaks appear at positions such as 12.8°, 25.8°, 29.6°, 32.5°, 35.3°, 50.9°, and 52.9°, indicating that single-phase MoTe2 can be synthesized at this temperature.
[0049] The scanning electron microscope (SEM) image of the molybdenum-based composite carbon material prepared in Comparative Example 4 is shown below. Figure 8It can be seen that agglomerated and stacked nanosheets with relatively thick layers grow on the surface of the carbon nanotube wall. The individual nanosheets have a size in the range of 100~300 nm and a thickness of about 30~40 nm.
[0050] Performance testing Sodium-ion batteries were assembled using the MoTe2-MoN composite hard carbon material prepared in Example 1 above: Active material (MoTe2-MoN composite hard carbon material), acetylene black, and PVDF (polyvinylidene fluoride) were added dropwise to N-methylpyrrolidone at a mass ratio of 8:1:1, and ground into a slurry. This slurry was then uniformly coated onto the surface of copper (Cu) foil using a scraper and dried at 110°C for 10 hours in a vacuum drying oven. The Cu foil containing the active material was then cut into 16 mm diameter circular negative electrode sheets. A sodium metal sheet was used as the counter electrode, glass fiber was selected as the separator, and 1 M NaClO4 (EC:DEC = 1:1, volume ratio) was used as the electrolyte. The batteries were assembled into CR2032 type batteries in an argon-protected glove box, sealed, and allowed to stand for 10 hours before electrochemical performance testing.
[0051] Figure 9 The first three CV curves of the MoTe2-MoN composite hard carbon material prepared in Example 1 at a scan rate of 0.5 mV / s are shown. The overlapping CV curves indicate that the electrode has high reversibility.
[0052] Figure 10 The capacitance contribution of the sodium-ion battery assembled from the MoTe2-MoN composite hard carbon material prepared in Example 1 is shown under a scan rate of 0.8 mV / s. The contribution rate of the capacitance charge storage to the total sodium storage is 85%, indicating that the built-in electric field effect in the MoTe2-MoN composite hard carbon material promotes the capacitance behavior of the material and is more conducive to enhancing cycle performance.
[0053] Figure 11The graph shows the cycling performance of the MoTe2-MoN composite hard carbon material prepared in Example 1 and the carbon materials prepared in Comparative Examples 1-3 at a current density of 0.5 A / g (where 1 is Comparative Example 1, 2 is Comparative Example 2, 3 is Comparative Example 3, and 4 is Example 1). As can be seen from the graph, the MoTe2-MoN composite hard carbon material prepared in Example 1 still maintains a reversible capacity of ~380 mAh / g after 80 cycles. This is mainly due to the significant improvement in the structural stability of the material from the introduction of MoN, which effectively alleviates volume expansion. Its micro / nano structure combines high stability with rapid sodium ion transport capability, thereby improving the cycle durability of the electrode. The reversible capacity of the composite hard carbon material in Comparative Example 1 after 80 cycles was ~245 mAh / g, while that in Comparative Example 2 was ~265 mAh / g, and in Comparative Example 3 it was ~306 mAh / g. Compared to Example 1, the performance degradation in Comparative Example 1 was due to the lower calcination temperature (500℃), incomplete reaction, and poor MoTe2 crystallinity, resulting in poor conductivity and low sodium ion insertion / extraction efficiency in the composite material. The improved performance of Comparative Example 2 compared to 500℃ was due to improved MoTe2 crystallinity, allowing for the growth of interconnected nanosheets and increasing the number of sodium storage active sites. The improved performance of Comparative Example 3 compared to 500℃ and 600℃ was attributed to the formation of a better MoTe2 phase, where the pore structure shortened the ion transport distance, thus contributing to performance improvement.
[0054] Figure 12 The graph shows the cycling performance of the composite hard carbon material prepared in Comparative Example 4 at a current density of 0.5 A / g. As can be seen from the graph, this composite hard carbon material retains a reversible capacity of ~342 mAh / g after 80 cycles. Due to the agglomeration and stacking of MoTe2 nanosheets, its relatively large thickness is unfavorable for efficient ion transport and reaction kinetics in subsequent electrochemical processes.
[0055] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for preparing a MoTe2-MoN composite hard carbon material, characterized in that, Includes the following steps: (1) Dissolve ammonium molybdate in water and add ethylenediamine to obtain a mixture. Then add hydrochloric acid dropwise until a precipitate is formed. After heating and reacting, separate the solid and liquid, wash and dry to obtain MoO3-EDA nanorods. (2) The MoO3-EDA nanorods obtained in step (1) were ultrasonically dispersed in water, urea solution was added, and then biomass hard carbon was added. After mixing evenly, the mixture was dried to obtain the composite precursor. (3) The composite precursor obtained in step (2) and tellurium powder are calcined together in a reducing atmosphere at a temperature of 800°C to achieve in-situ co-generation and composite of MoTe2 and MoN on a biomass hard carbon substrate, forming a MoTe2-MoN heterojunction, and obtaining the MoTe2-MoN composite hard carbon material. 2.The method of claim 1, wherein the MoTe 2-MoN composite hard carbon material is prepared by the following steps. In step (1), the mass ratio of ammonium molybdate to ethylenediamine is 1.28:1; the concentration of hydrochloric acid is 1 M.
3. The method for preparing the MoTe2-MoN composite hard carbon material according to claim 1, characterized in that, In step (1), the reaction temperature of the heating reaction is 40-70℃ and the reaction time is 1-3 h.
4. The method for preparing the MoTe2-MoN composite hard carbon material according to claim 1, characterized in that, In step (2), the mass ratio of the MoO3-EDA nanorods, urea in the urea solution, and biomass hard carbon is 0.1:(0.4-1):(0.2-0.4).
5. The method for preparing the MoTe2-MoN composite hard carbon material according to claim 1, characterized in that, In step (3), the mass ratio of tellurium powder to biomass hard carbon is (0.1-0.4):(0.2-0.4).
6. The method for preparing the MoTe2-MoN composite hard carbon material according to claim 1, characterized in that, In step (3), the calcination time is 3-7 h.
7. The method for preparing the MoTe2-MoN composite hard carbon material according to claim 1, characterized in that, In step (3), the reducing atmosphere includes hydrogen and argon.
8. The method for preparing the MoTe2-MoN composite hard carbon material according to claim 1, characterized in that, In step (2), the ultrasonic dispersion time is 0.5-1.5h.
9. A MoTe2-MoN composite hard carbon material, characterized in that, It is prepared according to any one of claims 1-8.
10. The application of the MoTe2-MoN composite hard carbon material as described in claim 9 in the preparation of sodium-ion batteries, characterized in that, The MoTe2-MoN composite hard carbon material is used as the negative electrode of sodium-ion batteries.