Silver-doped molybdenum carbide composite material and preparation method and application thereof

Abstract

The invention provides a silver-doped molybdenum carbide composite material as well as a preparation method and application thereof, and belongs to the technical field of lithium metal batteries. The preparation method of the silver-doped molybdenum carbide composite material comprises the following steps: (1) dispersing and dissolving hydrogen molybdenum bronze and silver salt in water, and then washing and drying to obtain a silver-doped hydrogen molybdenum bronze material; (2) mixing and dissolving the silver-doped hydrogen molybdenum bronze material, citric acid and a carbon source in a solvent, then heating, adding strong acid and an alkaline reagent for reaction, and drying to obtain xerogel; and (3) heating the dry gel to enable the gel to self-propagate so as to obtain a precursor, and finally calcining to obtain the silver-doped molybdenum carbide composite material. The prepared silver-doped molybdenum carbide composite negative electrode has good lithium affinity and conductivity, can effectively guide uniform deposition of lithium ions and inhibit growth of lithium dendrites, and can effectively improve the capacity and cycling stability of a lithium metal battery.

Description

Technical Field

[0001] This invention belongs to the technical field of lithium metal batteries, and particularly relates to a molybdenum carbide composite anode material. Background Art

[0002] Lithium metal batteries have seen rapid development in recent years due to their high theoretical specific capacity (3860 mAh / g) and lowest redox potential (-3.054 V) of lithium anodes, demonstrating enormous potential in energy storage systems, portable electronic devices, and new energy vehicles. However, lithium metal anodes suffer from problems such as rapid lithium dendrite growth during cycling, uneven lithium metal deposition, and large volume expansion, ultimately leading to reduced cycle life, severe interfacial side reactions, and hindering their practical application. To address these issues, researchers have proposed directionally depositing lithium metal onto lithiophilic metal sites, utilizing the properties of lithiophilic metals to achieve uniform and reversible lithium metal deposition. However, active metals (zinc, tin, silver, etc.) easily alloy with lithium, resulting in severe volume effects and significantly reduced battery life. While transition metals possess high theoretical specific capacity, their poor conductivity often precludes their practical application in lithium metal anodes.

[0003] Molybdenum carbide (MoCb) has become a research hotspot in the field of advanced energy materials in recent years due to its unique physicochemical properties and has been widely reported. Theoretical calculations and related experimental studies have confirmed that MoCb possesses excellent lithium storage performance. However, bulk MoCb suffers from poor conductivity and a small specific surface area. Patent publication number CN109256545A discloses a method for preparing and applying a nitrogen-doped MoCb / graphene composite material, belonging to the field of transition metal carbide-carbon materials technology. The preparation method includes the following steps: S1. Preparing water-soluble graphene oxide (GO) slurry using a modified Hummers method; S2. Surface modification of graphene oxide; S3. Preparation of the molybdenum salt and graphene oxide composite; S4. Preparation of the nitrogen-doped MoCb / graphene composite material. The addition of the modifier effectively disperses the MoCb nanoparticles and inhibits their aggregation, allowing for more complete exposure of their active sites. Nitrogen doping improves the conductivity of the material and introduces more active sites. Patent publication number CN108183203A discloses a method for preparing a multi-level structured molybdenum carbide / nitrogen-doped carbon composite microsphere electrode material, comprising the following steps: S1. Dissolving copper acetate, L-glutamic acid, and phosphomolybdic acid in water at 30-60℃ with stirring; S2. Dissolving melamine in water at 30-60℃ with stirring; S3. Mixing the solutions from steps S1 and S2, stirring and reacting at 50-90℃ for 12-72 hours, then filtering and washing the filter cake with ethanol, and vacuum drying at 50℃ for 24 hours to obtain a precursor; S4. Heating the precursor to 500-800℃ in an inert atmosphere, holding for 1-5 hours, and then slowly cooling to room temperature. The resulting product is stirred in FeCl3 solution at 60℃ for 6 hours, filtered, and the filter cake is washed with pure water. The filter cake is then vacuum dried at 80℃ for 24 hours. The nano-molybdenum carbide prepared by this method exhibits good dispersibility and a high specific surface area. The aforementioned composite materials do indeed possess good cycling performance and superior rate capability, improving the performance of molybdenum carbide to some extent. However, the above synthesis methods generally suffer from problems such as complex processes, harsh reaction conditions, high production costs, and low yields, making it difficult to meet the needs of large-scale industrial production. Therefore, exploring an efficient and low-cost synthesis method for molybdenum carbide-based composite materials is of great significance for promoting their practical application in the field of energy storage. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a silver-doped molybdenum carbide composite material, its preparation method, and its application. The prepared silver-doped molybdenum carbide composite anode exhibits excellent lithium affinity and conductivity, effectively guiding uniform lithium ion deposition and suppressing lithium dendrite growth, thereby effectively improving the capacity and cycle stability of lithium metal batteries.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A method for preparing a silver-doped molybdenum carbide composite material includes the following steps:

[0007] (1) Hydrogen molybdenum bronze and silver salt were dispersed and dissolved in water, and then washed and dried to obtain silver-doped hydrogen molybdenum bronze material;

[0008] (2) The silver-doped hydrogen molybdenum bronze material, citric acid and carbon source were mixed and dissolved in a solvent, then heated and strong acid and alkaline reagents were added to react and dry to obtain a dry gel;

[0009] (3) The dry gel is heated to allow the gel to self-propagate and obtain the precursor. Finally, it is calcined to obtain the silver-doped molybdenum carbide composite material.

[0010] The preparation method of the hydrogen molybdenum bronze is as follows: perchloric acid is added dropwise to ammonium molybdate solution to carry out hydrothermal reaction to obtain molybdenum trioxide material; the molybdenum trioxide material is dissolved in hydrochloric acid solution, and then zinc granules are added until the solution color changes from blue to dark purple, and the solution is washed and dried to obtain hydrogen molybdenum bronze material.

[0011] The molar ratio of perchloric acid to ammonium molybdate is 2-6:1-3; the hydrothermal reaction temperature is 160-190℃ and the time is 23-26h.

[0012] The ratio of molybdenum trioxide material to hydrochloric acid solution is 1-3:25-75 g / mL; the concentration of hydrochloric acid solution is 1-5 mol / L.

[0013] The silver salt is silver nitrate; the mass ratio of the silver salt to hydrogen molybdenum bronze is 1-2:5-10.

[0014] The carbon source is at least one of cellulose, sucrose, fructose, glucose, starch, lignin, chitosan, phenolic resin, polyethylene glycol, polyethylene, and polypropylene; the solvent is water; the strong acid is concentrated nitric acid or concentrated hydrochloric acid; and the alkaline reagent is ammonia.

[0015] The mass ratio of the silver-doped hydrogen molybdenum bronze material, carbon source, and citric acid is 1-3:3-9:1-3; the ratio of the silver-doped hydrogen molybdenum bronze material, strong acid, and alkaline reagent is 1-3g:8-10ml:2-5ml.

[0016] Preferably, the mass ratio of the silver-doped hydrogen-molybdenum bronze material to the carbon source is 1:1-6.

[0017] More preferably, the mass ratio of the silver-doped hydrogen-molybdenum bronze material to the carbon source is 1:3-5.

[0018] The reaction temperature in step (2) is 80-100℃, and the drying temperature is 70-90℃; the heating temperature in step (3) is 200-300℃, and the time is 1-3 hours; the calcination temperature is 900-1300℃, and the time is 3-8 hours. A silver-doped molybdenum carbide composite material includes metallic silver, hard carbon, and hydrogen molybdenum bronze (H). x MoO3), in which metallic silver is loaded in nanoscale form on the surface of hydrogen molybdenum bronze nanosheets, and hard carbon is combined with the layered hydrogen molybdenum bronze in a triangular pyramidal structure.

[0019] To form a silver-doped molybdenum carbide composite anode material.

[0020] The silver-doped molybdenum carbide composite material is a triangular pyramid-like composite sheet structure with pores.

[0021] An application of a silver-doped molybdenum carbide composite material in lithium batteries involves mixing the silver-doped molybdenum carbide composite material, a conductive agent, a binder, and a solvent to form a slurry, which is then coated onto a current collector to obtain a lithium battery negative electrode sheet.

[0022] The beneficial effects of this invention are:

[0023] (1) This invention prepared nano-silver composite transition metal oxide carbon materials (HC / Ag-Mo2C) and hydrogen molybdenum bronze (H) by the citric acid sol method. x MoO3 is a typical molybdenum copper hydroxide semiconductor material. Its unique layered tunnel structure facilitates ion insertion / extraction and exchange, giving it the ability to donate and accept protons. Meanwhile, H... x MoO3 has good reducing properties, enabling it to reduce some metal ions to elemental metals via H+. x MoO3 in situ reduction of Ag + Nanoparticles (5-10 nm) induce uniform lithium deposition. Furthermore, the Mo2C conductive framework (conductivity > 2000 S / m) in the HC / Ag-Mo2C material accelerates charge transport and alleviates volumetric strain. The porous structure constructed in the hard carbon material effectively mitigates dead lithium accumulation, inhibits lithium dendrite growth, and reduces interfacial side reactions.

[0024] (2) The silver-doped molybdenum carbide composite material of this invention, used as a lithium metal anode, exhibits excellent conductivity. A hydrogen intercalation strategy is employed to transform the poorly conductive transition metal molybdenum oxide into a highly conductive and metal-like hydrogen molybdenum bronze. Simultaneously, the reducing properties of the hydrogen molybdenum bronze enable the loading of silver nanoparticles at room temperature. The layered structure of the hydrogen molybdenum bronze facilitates the storage of silver nanoparticles, which possess excellent lithiophilicity, enabling interlayer lithium intercalation and reducing lithium dendrite growth. Furthermore, the hard carbon structure with a triangular pyramidal shape provides a cone-shaped barrier effect, guiding lithium ions to deposit along the edges and limiting the lateral expansion of deposited lithium. Simultaneously, the porous surface structure enables microporous lithium storage, providing more lithium ion storage and thus achieving a long and stable cycle life. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The image shows the SEM image of the hard carbon material in Comparative Example 1.

[0027] Figure 2 This is a SEM image of the hard carbon composite molybdenum carbide material in Example 2.

[0028] Figure 3 The image shows the SEM image of the silver-doped molybdenum carbide composite anode material in Example 3.

[0029] Figure 4 The deposition curves are for the electrodes in Examples 1, 2 and 4.

[0030] Figure 5 The cycling performance of the electrodes in Examples 1, 2 and 4 is shown. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] A silver-doped molybdenum carbide composite material, the preparation method includes the following steps:

[0034] 20 mL of 3 mol / L perchloric acid was added dropwise to 30 mL of 1 mol / L ammonium molybdate solution. After standing for 2 h, a transparent precursor solution was obtained. The precursor solution was transferred to a reactor and hydrothermally reacted at 180 °C for 24 h to obtain molybdenum trioxide material.

[0035] Molybdenum trioxide was dissolved in 100 mL of hydrochloric acid at room temperature. Zinc granules were added and the mixture was magnetically stirred. After the zinc granules had reacted completely, the solution was allowed to stand, the supernatant was poured off, and hydrochloric acid and zinc granules were added again, with stirring continued. This process was repeated three times until the precipitate in the solution turned completely dark blue. After washing, the precipitate was freeze-dried to obtain a dark blue-purple hydrogen molybdenum bronze material. 1 g of hydrogen molybdenum bronze powder was dissolved in 20 mL of deionized water, and 0.1 g of silver nitrate was dissolved in 5 mL of deionized water. After stirring thoroughly, the solutions were added to the hydrogen molybdenum bronze solution. After reacting for 12 hours, the lower precipitate was collected, centrifuged and washed three times with deionized water, and then dried to obtain Ag / H x MoO3 material.

[0036] Weigh out 0.8406g of citric acid powder, 2.058g of sucrose powder, and 0.5g of Ag / H. x MoO3 powder was dispersed in 15 mL of deionized water and then transferred to an oil bath at 90 °C. Under stirring, 4 mL of concentrated nitric acid and 1 mL of ammonia solution were added sequentially to the mixture. After reacting for 15 minutes, the mixture was dried in an oven at 80 °C to obtain a dry gel. The oven temperature was then increased to 250 °C, and after 2 hours, the gel self-propagated to obtain the precursor. Finally, silver-doped molybdenum carbide anode material was obtained by calcination at 1200 °C for 5 hours under an argon atmosphere. Figure 3 This is a scanning electron microscope image of the hard carbon composite molybdenum carbide material prepared in this example, showing silver nanoparticles loaded onto a hydrogen molybdenum bronze sheet. A slurry was formed by uniformly mixing silver-doped molybdenum carbide anode material, conductive carbon, and polyvinylidene fluoride in a mass ratio of 8:1:1 in a N-methylpyrrolidone solvent. This slurry was then coated onto a copper foil surface and dried to form a conductive carbon electrode with a coating thickness of 120 μm. This electrode was then used as the working electrode, with a lithium metal sheet as the counter electrode, and a 3.6 M LiFSI / DME-TTE organic lithium salt solution as the electrolyte, at a current of 5 mA / cm². 2 Current density and 1mAh / cm 2 Lithium deposition was performed at the areal capacity, and charge-discharge cycle tests were conducted under the same conditions. The corresponding nucleation overpotentials and cycle performance are shown in Table 2. The corresponding deposition curves are shown in... Figure 4 The cycle performance is shown in Figure 5As can be seen, the nucleation overpotential of the silver-doped molybdenum carbide electrode is only 58.6 mV, and the initial coulombic efficiency can reach 94.94%. This indicates that the lithium-affinity properties of silver and the porous triangular pyramidal hard carbon structure result in highly reversible lithium deposition and dissolution. At the same time, this silver-doped molybdenum carbide electrode can achieve more than 580 stable cycles, and the coulombic efficiency is still above 90%.

[0037] Example 2

[0038] A silver-doped molybdenum carbide composite material, the preparation method includes the following steps:

[0039] Weigh 1g of hydrogen molybdenum bronze powder and dissolve it in 20mL of deionized water. Weigh 0.2g of silver nitrate and dissolve it in 5mL of deionized water. After stirring evenly, add the solutions to the hydrogen molybdenum bronze powder. After reacting for 12 hours, take the lower precipitate, wash it three times with deionized water by centrifugation, and then dry it to obtain Ag / H x MoO3 material.

[0040] Weigh out 0.8406g of citric acid powder, 2.058g of sucrose powder, and 0.5g of Ag / H. x MoO3 powder was dispersed in 15 mL of deionized water and then transferred to an oil bath at 90 °C. Under stirring, 4 mL of concentrated nitric acid and 1 mL of ammonia solution were added sequentially to the mixture. After reacting for 15 minutes, the mixture was dried in an oven at 80 °C to obtain a dry gel. The oven temperature was then increased to 250 °C, and after 2 hours, the gel self-propagated to obtain the precursor. Finally, silver-doped molybdenum carbide anode material was obtained by calcination at 1200 °C for 5 hours under an argon atmosphere.

[0041] The only difference from Example 1 is that the reaction ratio of silver nitrate to molybdenum bronze is 2:10; all other implementation methods are the same as in Example 1. The corresponding cycling performance is shown in Table 1. Compared to Example 1, the first-efficiency of the 20wt% silver-loaded molybdenum bronze material is 82.1%, indicating that the high Ag concentration not only increases cost but also promotes excessive growth of the Li-Ag alloy layer, increases the risk of SEI cracking, and accelerates electrolyte decomposition.

[0042] Table 1 Initial Coulomb Efficiency for Different Silver Loadings

[0043]

[0044] Example 3

[0045] A silver-doped molybdenum carbide composite material, the preparation method includes the following steps:

[0046] Weigh 1g of hydrogen molybdenum bronze powder and dissolve it in 20mL of deionized water. Weigh 0.2g of silver nitrate and dissolve it in 5mL of deionized water. After stirring evenly, add the solutions to the hydrogen molybdenum bronze powder. After reacting for 12 hours, take the lower precipitate, wash it three times with deionized water by centrifugation, and then dry it to obtain Ag / H x MoO3 material.

[0047] Weigh out 0.8406g of citric acid powder, 2.058g of sucrose powder, and 2.058g of Ag / H. x MoO3 powder was dispersed in 15 mL of deionized water and then transferred to an oil bath at 90 °C. Under stirring, 4 mL of concentrated nitric acid and 1 mL of ammonia solution were added sequentially to the mixture. After reacting for 15 minutes, the mixture was dried in an oven at 80 °C to obtain a dry gel. The oven temperature was then increased to 250 °C, and after 2 hours, the gel self-propagated to obtain the precursor. Finally, silver-doped molybdenum carbide anode material was obtained by calcination at 1200 °C for 5 hours under an argon atmosphere.

[0048] Example 4

[0049] A silver-doped molybdenum carbide composite material, the preparation method includes the following steps:

[0050] Weigh 1g of hydrogen molybdenum bronze powder and dissolve it in 20mL of deionized water. Weigh 0.2g of silver nitrate and dissolve it in 5mL of deionized water. After stirring evenly, add the solutions to the hydrogen molybdenum bronze powder. After reacting for 12 hours, take the lower precipitate, wash it three times with deionized water by centrifugation, and then dry it to obtain Ag / H x MoO3 material.

[0051] Weigh out 0.8406g of citric acid powder, 2.058g of sucrose powder, and 1.029g of Ag / H. x MoO3 powder was dispersed in 15 mL of deionized water and then transferred to an oil bath at 90 °C. Under stirring, 4 mL of concentrated nitric acid and 1 mL of ammonia solution were added sequentially to the mixture. After reacting for 15 minutes, the mixture was dried in an oven at 80 °C to obtain a dry gel. The oven temperature was then increased to 250 °C, and after 2 hours, the gel self-propagated to obtain the precursor. Finally, silver-doped molybdenum carbide anode material was obtained by calcination at 1200 °C for 5 hours under an argon atmosphere.

[0052] Example 5

[0053] A silver-doped molybdenum carbide composite material, the preparation method includes the following steps:

[0054] Weigh 1g of hydrogen molybdenum bronze powder and dissolve it in 20mL of deionized water. Weigh 0.2g of silver nitrate and dissolve it in 5mL of deionized water. After stirring evenly, add the solutions to the hydrogen molybdenum bronze powder. After reacting for 12 hours, take the lower precipitate, wash it three times with deionized water by centrifugation, and then dry it to obtain Ag / H xMoO3 material.

[0055] Weigh out 0.8406g of citric acid powder, 2.058g of sucrose powder, and 0.343g of Ag / H. x MoO3 powder was dispersed in 15 mL of deionized water and then transferred to an oil bath at 90 °C. Under stirring, 4 mL of concentrated nitric acid and 1 mL of ammonia solution were added sequentially to the mixture. After reacting for 15 minutes, the mixture was dried in an oven at 80 °C to obtain a dry gel. The oven temperature was then increased to 250 °C, and after 2 hours, the gel self-propagated to obtain the precursor. Finally, silver-doped molybdenum carbide anode material was obtained by calcination at 1200 °C for 5 hours under an argon atmosphere.

[0056] Table 2. Nucleation overpotential and cycling performance of lithium metal electrodes prepared with different sucrose and Ag / HxMoO3 mass ratios.

[0057]

[0058] The results show that within the optimal mass ratio of sucrose to Ag / HxMoO3 (1:3–5), the silver-doped molybdenum carbide anode material exhibits the lowest nucleation overpotential, the highest initial coulombic efficiency, and the best cycle life. When the Ag / HxMoO3 content is insufficient, the electrode lacks enough lithiophilic sites, leading to a higher nucleation overpotential, lower coulombic efficiency, and shorter cycle life. When the sucrose content is insufficient, the electrode's conductivity deteriorates, resulting in increased electrochemical polarization, higher nucleation overpotential, and lower cycle life.

[0059] Example 6

[0060] A silver-doped molybdenum carbide composite material, the preparation method includes the following steps:

[0061] Weigh 1g of hydrogen molybdenum bronze powder and dissolve it in 20mL of deionized water. Weigh 0.4g of silver nitrate and dissolve it in 5mL of deionized water. After stirring evenly, add the solutions to the hydrogen molybdenum bronze powder. After reacting for 24 hours, take the lower precipitate, wash it three times with deionized water by centrifugation, and then dry it to obtain Ag / H x MoO3 material.

[0062] Weigh out 1.5g of citric acid powder, 2.058g of glucose, and 0.5g of Ag / H. x MoO3 powder was dispersed in 15 mL of deionized water and then transferred to an oil bath at 100 °C. Under stirring, 5 mL of concentrated nitric acid and 2 mL of ammonia solution were added sequentially to the mixture. After reacting for 15 minutes, the mixture was transferred to an oven at 80 °C to dry and obtain a dry gel. The oven temperature was then increased to 300 °C, and after 1 hour, the gel self-propagated to obtain the precursor. Finally, silver-doped molybdenum carbide anode material was obtained by calcination at 900 °C for 8 hours under an argon atmosphere.

[0063] Example 7

[0064] A silver-doped molybdenum carbide composite material, the preparation method includes the following steps:

[0065] Weigh 1g of hydrogen molybdenum bronze powder and dissolve it in 20mL of deionized water. Weigh 0.3g of silver nitrate and dissolve it in 5mL of deionized water. After stirring evenly, add the solutions to the hydrogen molybdenum bronze powder. After reacting for 24 hours, take the lower precipitate, wash it three times with deionized water by centrifugation, and then dry it to obtain Ag / H x MoO3 material.

[0066] Weigh out 0.5g of citric acid powder, 2.058g of chitosan, and 0.3g of Ag / H. x MoO3 powder was dispersed in 15 mL of deionized water and then transferred to an oil bath at 80 °C. Under stirring, 1.5 mL of concentrated nitric acid and 0.5 mL of ammonia solution were added sequentially to the mixture. After reacting for 15 minutes, the mixture was transferred to an oven at 70 °C to dry and obtain a dry gel. The oven temperature was then increased to 300 °C, and after 1 hour, the gel self-propagated to obtain the precursor. Finally, silver-doped molybdenum carbide anode material was obtained by calcination at 1300 °C for 3 hours under an argon atmosphere.

[0067] Comparative Example 1

[0068] A hard carbon material, the preparation method includes the following steps:

[0069] 0.8406 g of citric acid powder and 2.058 g of sucrose powder were weighed and dispersed in 15 mL of deionized water. The mixture was then transferred to an oil bath at 90 °C. Under stirring, 4 mL of concentrated nitric acid and 1 mL of ammonia solution were added sequentially to the mixture. After reacting for 15 minutes, the mixture was transferred to an oven at 80 °C to dry and obtain a dry gel. The oven temperature was then increased to 250 °C to allow the gel to self-propagate and obtain the precursor. Finally, the hard carbon material was obtained by calcination at 1200 °C for 5 hours under an argon atmosphere. Figure 1 This is a scanning electron microscope image of the hard carbon material prepared in this example. The hard carbon sample has a triangular pyramidal structure with an edge length of approximately 18 μm and a height of approximately 10 μm.

[0070] Hard carbon material, conductive carbon, and polyvinylidene fluoride were uniformly mixed in a mass ratio of 8:1:1 in a N-methylpyrrolidone solvent to form a slurry, which was then coated onto a copper foil surface and dried to form a conductive carbon electrode with a coating thickness of 120 μm. This electrode was then used as the working electrode, with a lithium metal sheet as the counter electrode, and a 3.6 M LiFSI / DME-TTE organic lithium salt solution as the electrolyte, at a current of 5 mA / cm². 2 Current density and 1mAh / cm 2Lithium deposition was performed at the areal capacity, and charge-discharge cycle tests were conducted under the same conditions. The corresponding deposition curves are shown below. Figure 4 The cycle performance is shown in Figure 5 As can be seen, the hard carbon electrode has the highest nucleation overpotential (119.6 mV) compared to other example electrode materials, and its initial coulombic efficiency is 89.41%, which drops sharply after 350 stable cycles. This indicates that hard carbon does not have lithium metal-induced lithium metal deposition and is prone to lithium dendrite growth, thereby reducing the cycle life of the electrode.

[0071] Comparative Example 2

[0072] A hard carbon composite molybdenum carbide material, the preparation method includes the following steps:

[0073] 0.8406 g of citric acid powder, 2.058 g of sucrose powder, and 0.5 g of HxMoO3 were weighed and dispersed in 15 mL of deionized water. The mixture was then transferred to an oil bath at 90 °C. Under stirring, 4 mL of concentrated nitric acid and 1 mL of ammonia solution were added sequentially to the mixture. After reacting for 15 minutes, the mixture was dried in an oven at 80 °C to obtain a dry gel. The oven temperature was then increased to 250 °C, and the gel was allowed to self-propagate for 2 hours to obtain the precursor. Finally, the hard carbon composite molybdenum carbide material was obtained by calcination at 1200 °C for 5 hours under an argon atmosphere. Figure 2 This is a scanning electron microscope image of the hard carbon composite molybdenum carbide material prepared in this example. The hard carbon composite molybdenum carbide sample has a sheet-like structure.

[0074] Hard carbon composite molybdenum carbide, conductive carbon, and polyvinylidene fluoride were uniformly mixed in a mass ratio of 8:1:1 in a nitrogen-methylpyrrolidone solvent to form a slurry. This slurry was then coated onto a copper foil surface and dried to form a conductive carbon electrode with a coating thickness of 120 μm. This electrode was then used as the working electrode, with a lithium metal sheet as the counter electrode, and a 3.6 M LiFSI / DME-TTE organic lithium salt solution as the electrolyte, at a current of 5 mA / cm². 2 Current density and 1mAh / cm 2 Lithium deposition was performed at the areal capacity, and charge-discharge cycle tests were conducted under the same conditions. The corresponding deposition curves are shown below. Figure 4 The cycle performance is shown in Figure 5 The hard carbon composite molybdenum oxide material exhibits a large lithium nucleation overpotential (99.8 mV) due to the absence of a silver-based lithium-bearing metal. Furthermore, the initial coulombic efficiency of the conductive carbon electrode (89.85%) is lower than that of the aluminum-titanium-iron-nickel-copper high-entropy alloy electrode. Therefore, this electrode can only achieve stable cycling for 362 cycles during long charge-discharge cycles, after which the coulombic efficiency fluctuates significantly, indicating severe lithium dendrite growth.

[0075] Comparative Example 3

[0076] Preparation of silver-doped hydrogen molybdenum bronze materials

[0077] Molybdenum trioxide was dissolved in 100 mL of hydrochloric acid at room temperature. Zinc granules were added and the mixture was magnetically stirred. After the zinc granules had reacted completely, the solution was allowed to stand, the supernatant was poured off, and hydrochloric acid and zinc granules were added again, with stirring continued. This process was repeated twice until the precipitate in the solution turned completely dark blue. After washing, the precipitate was freeze-dried to obtain a dark blue-purple hydrogen molybdenum bronze material. 1 g of hydrogen molybdenum bronze powder was dissolved in 20 mL of deionized water, and 0.1 g of silver nitrate was dissolved in 5 mL of deionized water. After stirring thoroughly, the solutions were added to the hydrogen molybdenum bronze solution. After reacting for 12 hours, the lower precipitate was collected, centrifuged and washed three times with deionized water, and then dried to obtain Ag / H x MoO3 material.

[0078] Ag / H x MoO3 material, conductive carbon, and polyvinylidene fluoride were uniformly mixed in a mass ratio of 8:1:1 in a N-methylpyrrolidone solvent to form a slurry, which was then coated onto a copper foil surface and dried to form a conductive carbon electrode with a coating thickness of 120 μm. This electrode was then used as the working electrode, with a lithium metal sheet as the counter electrode, and a 3.6 M LiFSI / DME-TTE organic lithium salt solution as the electrolyte, at a current of 5 mA / cm². 2 Current density and 1mAh / cm 2 Lithium deposition was performed at the areal capacity, and charge-discharge cycle tests were conducted under the same conditions. The corresponding cycle performance is shown in Table 1. Silver, as a lithium-philic metal, guides uniform lithium-ion deposition through its low lithium nucleation energy barrier (<0.2 eV), effectively suppressing dendrite growth. Ag nanoparticles (5-10 nm) modified H... x The MoO3 conductive framework forms a high diffusion channel, synergistically stabilizing the SEI interface through the surface Li-Ag alloying reaction. Furthermore, this silver-loaded hydrogen-molybdenum bronze electrode exhibits a high initial coulombic efficiency of 85.8%, suggesting highly reversible lithium deposition and dissolution behavior.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a silver-doped molybdenum carbide composite material, characterized in that, Includes the following steps: (1) Hydrogen molybdenum bronze and silver salt were dispersed and dissolved in water, and then washed and dried to obtain silver-doped hydrogen molybdenum bronze material; (2) The silver-doped hydrogen molybdenum bronze material, citric acid and carbon source were mixed and dissolved in a solvent, then heated and strong acid and alkaline reagents were added to react and dry to obtain a dry gel; (3) The dry gel is heated to allow the gel to self-propagate and obtain the precursor. Finally, it is calcined to obtain the silver-doped molybdenum carbide composite material.

2. The method for preparing the silver-doped molybdenum carbide composite material according to claim 1, characterized in that, The preparation method of the hydrogen molybdenum bronze is as follows: perchloric acid is added dropwise to ammonium molybdate solution to carry out hydrothermal reaction to obtain molybdenum trioxide material; the molybdenum trioxide material is dissolved in hydrochloric acid solution, and then zinc granules are added until the solution color changes from blue to dark purple, and the solution is washed and dried to obtain hydrogen molybdenum bronze material.

3. The method for preparing the silver-doped molybdenum carbide composite material according to claim 2, characterized in that, The molar ratio of perchloric acid to ammonium molybdate is 2-6:1-3; the hydrothermal reaction temperature is 160-190℃ and the time is 23-26h.

4. The method for preparing the silver-doped molybdenum carbide composite material according to any one of claims 1-3, characterized in that, The ratio of molybdenum trioxide material to hydrochloric acid solution is 1-3:25-75 g / mL; the concentration of hydrochloric acid solution is 1-5 mol / L.

5. The method for preparing the silver-doped molybdenum carbide composite material according to claim 4, characterized in that, The silver salt is silver nitrate; the mass ratio of the silver salt to hydrogen molybdenum bronze is 1-2:5-10.

6. The method for preparing the silver-doped molybdenum carbide composite material according to claim 5, characterized in that, The carbon source is at least one of cellulose, sucrose, fructose, glucose, starch, lignin, chitosan, phenolic resin, polyethylene glycol, polyethylene, and polypropylene; the solvent is water; the strong acid is concentrated nitric acid or concentrated hydrochloric acid; and the alkaline reagent is ammonia.

7. The method for preparing the silver-doped molybdenum carbide composite material according to claim 6, characterized in that, The mass ratio of the silver-doped hydrogen molybdenum bronze material, carbon source, and citric acid is 1-3:3-9:1-3; the ratio of the silver-doped hydrogen molybdenum bronze material, strong acid, and alkaline reagent is 1-3g:8-10ml:2-5ml.

8. The method for preparing the silver-doped molybdenum carbide composite material according to claim 7, characterized in that, The reaction temperature in step (2) is 80-100℃, and the drying temperature is 70-90℃; the heating temperature in step (3) is 200-300℃; the calcination temperature is 900-1300℃, and the time is 3-8h.

9. The silver-doped molybdenum carbide composite material prepared by the method according to any one of claims 1-8, characterized in that, The silver-doped molybdenum carbide composite material is a triangular pyramid-like composite sheet structure with pores.

10. The application of the silver-doped molybdenum carbide composite material according to claim 9 in lithium batteries, characterized in that, A silver-doped molybdenum carbide composite material, a conductive agent, a binder, and a solvent are mixed to form a slurry, which is then coated onto a current collector to obtain a lithium battery anode sheet.

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