VZrNbTaWMoCr high-entropy nano-alloy layer coated carbon fiber composite electrode material and preparation method and application thereof

Abstract

The invention discloses a preparation method of a VZrNbTaWMoCr high-entropy nano-alloy layer coated carbon fiber composite electrode material, and the preparation method comprises the steps: adding metal salts of vanadium, zirconium, niobium, tantalum, tungsten, molybdenum and chromium in equal metal element molar ratio into a solvent for dissolving, fully stirring at normal temperature, and carrying out ultrasonic treatment to obtain a VZrNbTaWMoCr precursor solution with the total metal ion concentration of 5-20 mol / L; infiltrating carbon paper by adopting the precursor solution of VZrNbTaWMoCr prepared in the first step, standing at room temperature for 5-10 minutes, repeating the steps for 3-6 times, and then performing vacuum drying; 2, the carbon paper dried in the step 2 is conveyed to a tubular furnace filled with inert atmosphere, the temperature is increased to 800-1600 DEG C from the room temperature, heat preservation is conducted for 30 min-2 h, then the carbon paper is naturally cooled to the room temperature along with the furnace, a sample is taken out, and the VZrNbTaWMoCr high-entropy nano-alloy layer coated carbon fiber composite material is obtained and applied to a negative-electrode-free lithium metal battery to reduce the volume expansion fluctuation rate in the lithium plating / stripping process, and the lithium plating / stripping performance of the negative-electrode-free lithium metal battery is improved. The uniform deposition of lithium in the battery is promoted, the formation of lithium dendrites is avoided, and the cycle stability and capacity retention ratio of the negative-electrode-free lithium metal battery are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of functional materials, relates to a composite electrode material, and specifically relates to a VZrNbTaWMoCr high-entropy nano alloy layer coated carbon fiber composite electrode material, and a preparation method and application thereof. Background Art

[0002] At present, more than 80% of the demand for energy systems in my country's economic and social development comes from traditional fossil energy, including oil, coal and natural gas. In order to solve energy and ecological problems and build an energy supply system in the new era, the research on renewable energy and storage technology has attracted great attention from all over the world, and energy storage will also become an important challenge in the future development of human society.

[0003] Lithium metal batteries have attracted much attention due to their high theoretical capacity and low potential, but there are still many challenges in practical application, such as the growth and volume expansion of lithium dendrites. Lithium dendrites may cause short circuits, and in the presence of flammable liquid / polymer electrolytes, short circuits may turn into dangerous fires and explosions (Figure). Therefore, finding solutions to promote the commercial application of lithium metal batteries has become one of the current research hotspots. Through the careful design of various elements, high entropy alloys provide unique tunable properties compared with traditional single or alloy materials.

[0004] Since the lithium metal of the negative electrode of the anode is completely provided by the positive electrode, the anode-free lithium metal battery has outstanding theoretical advantages, such as significantly reduced battery mass and thickness, high mass energy density and volume energy density, which can simplify the preparation process and reduce battery costs. The preparation of anode-free lithium metal batteries will significantly reduce the demand for lithium metal and save resources. Therefore, it is a very important direction to study high entropy alloy carbon fiber as an electrode material for anode-free lithium metal batteries. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a VZrNbTaWMoCr high-entropy nano-alloy layer coated carbon fiber composite electrode material and a preparation method and application thereof. The material is used in a negative electrode-free lithium metal battery to reduce the volume expansion fluctuation rate during lithium plating / stripping, promote the uniform deposition of lithium in the battery, avoid the formation of lithium dendrites, and improve the cycle stability capacity retention rate of the negative electrode-free lithium metal battery.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material comprises the following steps:

[0008] Step 1: adding metal salts of vanadium, zirconium, niobium, tantalum, tungsten, molybdenum and chromium in equal molar ratios of metal elements into a solvent and dissolving them, stirring them fully at room temperature and ultrasonically treating them to obtain a VZrNbTaWMoCr precursor solution with a total metal ion concentration of 5 to 20 mol / L;

[0009] Step 2: Infiltrate carbon paper with the precursor solution of VZrNbTaWMoCr prepared in step 1, place at room temperature for 5 to 10 minutes, repeat the infiltration and room temperature steps 3 to 6 times, and then vacuum dry;

[0010] Step 3: transport the carbon paper dried in step 2 to a tubular furnace filled with an inert atmosphere, heat it from room temperature to 800-1600°C, keep it warm for 30min-2h, then naturally cool it to room temperature with the furnace, take out the sample to obtain a VZrNbTaWMoCr high entropy nano alloy layer-coated carbon fiber composite material.

[0011] Preferably, the metal salt includes any one of sulfate, chloride or nitrate and hydrates thereof.

[0012] Preferably, the solvent in step 1 includes any one of anhydrous ethanol, water, and a mixed solution of anhydrous ethanol and water in a volume ratio of 1:1.

[0013] Preferably, the sufficient stirring and ultrasonic treatment in step 1 is to stir magnetically for 1 to 4 hours at room temperature and then place in an ultrasonic cleaning machine for ultrasonic treatment for 1 to 2 hours.

[0014] Preferably, the carbon paper in step 2 is wetted by any one of dripping with a pipette gun, spraying with an electrostatic spray gun, or soaking.

[0015] Preferably, the vacuum drying in step 2 is vacuum drying at 80° C. for 12 to 24 hours.

[0016] Preferably, the inert atmosphere described in step three includes any one of argon, nitrogen, and argon-hydrogen mixed gas.

[0017] Preferably, the heating rate of the tubular furnace described in step three is 1° C. / min to 10° C. / min.

[0018] The present invention also protects a VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material prepared by the method as described above and its application in a negative electrode-free lithium metal battery.

[0019] Compared with the prior art, the present invention has the following technical effects:

[0020] The present invention prepares carbon fibers loaded with high-entropy nano alloys by a high-temperature redox method. The lattice distortion and multi-element synergistic effect of the VZrNbTaWMoCr high-entropy alloy can provide abundant active centers, which are beneficial to promoting interface reaction kinetics and regulating uniform lithium deposition, and provide the lithium-philic property and good conductivity of the electrode. The porous carbon fibers loaded with high-entropy alloy nanoparticles provide a large specific surface area, which is beneficial to reducing local current density and can actively regulate lithium deposition. The unique structure of the 3D carbon fibers can provide a large specific surface area, reduce the volume expansion fluctuation rate during lithium plating / stripping processes, promote uniform lithium deposition in the battery, avoid the formation of lithium dendrites, and improve the cycle stability capacity retention rate of the negative electrode-free lithium metal battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a SEM image of the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material prepared in Example 1;

[0022] Figure 2 This is an EDS image of the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material prepared in Example 1;

[0023] Figure 3 XRD pattern of the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material prepared in Example 1;

[0024] Figure 4 The half-cell performance diagram (5 mA cm) of the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material prepared in Example 1 -2 / 1mAh cm -2 );

[0025] Figure 5 This is the full cell performance diagram (0.5C) of the VZrNbTaWMoCr high entropy alloy / carbon fiber composite material prepared in Example 1;

[0026] Figure 6 This is the full battery performance diagram of the VZrNbTaWMoCr high entropy alloy / carbon fiber composite material prepared in Example 1 (1C). DETAILED DESCRIPTION

[0027] The specific contents of the present invention are further explained in detail below in conjunction with embodiments.

[0028] In the following embodiments, the volume proportion of hydrogen in the argon-hydrogen mixed gas is 10%.

[0029] Example 1

[0030] This embodiment provides a method for preparing a VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material, specifically comprising the following steps:

[0031] Step 1, respectively taking 0.02 mmol of vanadium chloride, zirconium chloride, niobium chloride, tantalum chloride, tungsten chloride, molybdenum chloride and chromium chloride and dissolving them in 10 mL of anhydrous ethanol solvent, the solution was magnetically stirred for 2 hours at room temperature and then placed in an ultrasonic cleaning machine for 1 hour to obtain a VZrNbTaWMoCr precursor solution with a total metal ion concentration of 15 mol / L;

[0032] Step 2: Cut the carbon paper into discs with a diameter of 1 cm, pick up the carbon paper with tweezers, dip it in the precursor solution, soak it, take it out immediately, and place it at room temperature for 5 minutes. Repeat the soaking and room temperature steps 3 times, and then place it in a positive vacuum drying oven at 80°C for 12 hours;

[0033] Step 3: transport the dried carbon paper to a tubular furnace filled with argon atmosphere, heat it from room temperature to 1100°C at a rate of 1°C / min, keep it warm for 1 hour, and then naturally cool it to room temperature with the furnace. Take out the sample to obtain a VZrNbTaWMoCr high-entropy nano alloy layer-coated carbon fiber composite material.

[0034] The VZrNbTaWMoCr high entropy alloy / carbon fiber composite material prepared in Example 1 was tested, and the results are as follows:

[0035] 1. Morphology

[0036] Figure 1 This is a SEM image of the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material prepared in Example 1. From the image, it can be seen that the high entropy particles are evenly coated on the carbon fiber.

[0037] Figure 2 This is the EDS image of the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material prepared in Example 1; Figure 2 It can be seen that each element is evenly dispersed in the carbon fiber, which means that the high entropy alloy material is successfully prepared.

[0038] 2 Structure

[0039] Figure 3 The XRD pattern of the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material prepared in Example 1; Figure 3 The X-ray diffraction peaks of the VZrNbTaWMoCr high entropy nanoalloy shown are mainly (110), (200), and (211);

[0040] 3 Electrochemical performance

[0041] Figure 4 The electrochemical performance diagram of the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material prepared in Example 1; Figure 4 As shown, the high entropy alloy / carbon fiber material is used as the negative electrode, and the lithium metal is used as the positive electrode to assemble a half-cell. Under the conditions of current density of 5mAcm-2 and specific capacity of 1mAh cm-2, the electrode stability is tested, and the average coulomb efficiency value is 99.2% after 150 stable cycles. This shows that the VZrNbTaWMoCr high entropy nanoalloy guides the uniform deposition of lithium.

[0042] Figure 5 The performance diagram of the full battery of the VZrNbTaWMoCr high entropy alloy / carbon fiber composite material prepared in Example 1 at a current density of 0.5C; Figure 5 As shown, the negative electrode material and LFP positive electrode material prepared in Example 1 were assembled to assemble a negative electrode-free lithium metal battery. Specifically, the initial capacity of the full battery at 0.5C was 116.77 mAh / g, and the capacity after 200 cycles was 102.86 mAh / g, with a capacity retention rate of 85.96%. This proves that the VZrNbTaWMoCr high entropy alloy / carbon fiber composite material has good rate performance as a negative electrode.

[0043] Figure 6 The performance diagram of the full battery of the VZrNbTaWMoCr high entropy alloy / carbon fiber composite material prepared in Example 1 at a current density of 1C; Figure 6 As shown, the negative electrode material prepared in Example 1 and the LFP positive electrode material were assembled to assemble a negative electrode-free lithium metal battery. Specifically, after the full battery was activated for 3 cycles at 1C, the initial capacity was 106.15 mAh / g, the capacity was 107.65 mAh / g after 200 cycles, and the average coulombic efficiency was 99.77%. It is proved that the VZrNbTaWMoCr high entropy alloy / carbon fiber composite material as a negative electrode material regulates lithium deposition and inhibits dendrite growth with stable cycle performance.

[0044] Example 2

[0045] This embodiment provides a method for preparing a VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material, specifically comprising the following steps:

[0046] Step 1, respectively adding vanadium chloride, zirconium chloride, niobium chloride, tantalum chloride, tungsten chloride, molybdenum chloride and chromium chloride in equal molar ratios of metal elements into anhydrous ethanol solvent for dissolution, and the solution is magnetically stirred for 3 hours at room temperature and then placed in an ultrasonic cleaning machine for 1 hour to obtain a VZrNbTaWMoCr precursor solution with a total metal ion concentration of 10 mol / L;

[0047] Step 2: Cut the carbon paper into discs with a diameter of 1 cm, pick up the carbon paper with tweezers, dip it in the precursor solution, soak it, take it out immediately, and place it at room temperature for 5 minutes. Repeat the soaking and room temperature steps 3 times, and then place it in a positive vacuum drying oven at 80°C for 24 hours;

[0048] Step 3: transport the dried carbon paper to a tubular furnace filled with argon atmosphere, heat it from room temperature to 1000°C at a rate of 10°C / min, keep it warm for 1 hour, and then naturally cool it to room temperature with the furnace. Take out the sample to obtain a VZrNbTaWMoCr high-entropy nano alloy layer-coated carbon fiber composite material.

[0049] Example 3

[0050] This embodiment provides a method for preparing a VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material, specifically comprising the following steps:

[0051] Step 1, respectively adding vanadium chloride, zirconium chloride, niobium chloride, tantalum chloride, tungsten chloride, molybdenum chloride and chromium chloride in equal molar ratios of metal elements into anhydrous ethanol solvent for dissolution, and the solution is magnetically stirred for 4 hours at room temperature and then placed in an ultrasonic cleaning machine for 2 hours to obtain a VZrNbTaWMoCr precursor solution with a total metal ion concentration of 20 mol / L;

[0052] Step 2: Cut the carbon paper into discs with a diameter of 1 cm, pick up the carbon paper with tweezers, dip it in the precursor solution, soak it, take it out immediately, and place it at room temperature for 8 minutes. Repeat the soaking and room temperature steps 5 times, and then place it in a positive vacuum drying oven at 80°C for 24 hours;

[0053] Step 3: transport the dried carbon paper to a tubular furnace filled with argon atmosphere, heat it from room temperature to 800°C at a rate of 2°C / min, keep it warm for 1.5 hours, then cool it naturally to room temperature with the furnace, take out the sample to obtain a VZrNbTaWMoCr high-entropy nano alloy layer-coated carbon fiber composite material.

[0054] Example 4

[0055] This embodiment provides a method for preparing a VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material, specifically comprising the following steps:

[0056] Step 1, respectively adding vanadium sulfate, zirconium sulfate, niobium sulfate, tantalum sulfate, tungsten sulfate, molybdenum sulfate and chromium sulfate of equal metal element molar ratio into a mixed solution prepared by anhydrous ethanol and water in a volume ratio of 1:1 to dissolve, the solution is magnetically stirred for 3 hours at room temperature and then placed in an ultrasonic cleaning machine for 1.5 hours to obtain a VZrNbTaWMoCr precursor solution with a total metal ion concentration of 5 mol / L;

[0057] Step 2: Cut the carbon paper into discs with a diameter of 1 cm, pick up the carbon paper with tweezers, and use a pipette to drop 15 μL of the precursor solution onto the carbon paper at a time, and place it at room temperature for 10 minutes. Repeat the steps of soaking and placing it at room temperature for 6 times, and then place it in a positive vacuum drying oven at 80°C for 18 hours;

[0058] Step 3: transport the dried carbon paper to a tubular furnace filled with nitrogen atmosphere, heat it from room temperature to 900°C at a rate of 5°C / min, keep it warm for 2 hours, and then naturally cool it to room temperature with the furnace. Take out the sample to obtain a VZrNbTaWMoCr high-entropy nano alloy layer-coated carbon fiber composite material.

[0059] Example 5

[0060] This embodiment provides a method for preparing a VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material, specifically comprising the following steps:

[0061] Step 1, respectively adding vanadium nitrate, zirconium nitrate, niobium nitrate, tantalum nitrate, tungsten nitrate, nitric acid and chromium nitrate in equal molar ratios of metal elements into water to dissolve, the solution is magnetically stirred for 1 hour at room temperature and then placed in an ultrasonic cleaning machine for 1 hour to obtain a VZrNbTaWMoCr precursor solution with a total metal ion concentration of 14 mol / L;

[0062] Step 2: Cut the carbon paper into discs with a diameter of 1 cm, pick up the carbon paper with tweezers, spray 15 μL of the precursor solution onto the carbon paper with an electrostatic spray gun, leave it at room temperature for 10 minutes, repeat the steps of soaking and leaving it at room temperature for 5 times, and then place it in a positive vacuum drying oven at 80°C for 18 hours;

[0063] Step 3: transport the dried carbon paper to a tubular furnace filled with an argon-hydrogen mixed gas atmosphere, heat it from room temperature to 1600°C at a rate of 8°C / min, keep it warm for 30 minutes, and then naturally cool it to room temperature with the furnace. Take out the sample to obtain a VZrNbTaWMoCr high-entropy nano alloy layer-coated carbon fiber composite material.

[0064] It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it; VZrNbTaWMoCr can be selected in addition to the several methods listed in the embodiments, and can also be other combinations. Without departing from the concept of the present invention, the deduction or replacement made by those skilled in the art shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material, characterized in that: The following steps are included: Step 1: adding metal salts of vanadium, zirconium, niobium, tantalum, tungsten, molybdenum and chromium in equal molar ratios of metal elements into a solvent and dissolving them, stirring them fully at room temperature and ultrasonically treating them to obtain a VZrNbTaWMoCr precursor solution with a total metal ion concentration of 5 to 20 mol / L; Step 2: Infiltrate carbon paper with the precursor solution of VZrNbTaWMoCr prepared in step 1, place at room temperature for 5 to 10 minutes, repeat the infiltration and room temperature steps 3 to 5 times, and then vacuum dry; Step 3: transport the carbon paper dried in step 2 to a tubular furnace filled with an inert atmosphere, heat it from room temperature to 800-1600°C, keep it warm for 30min-2h, then naturally cool it to room temperature with the furnace, take out the sample to obtain a VZrNbTaWMoCr high entropy nano alloy layer-coated carbon fiber composite material.

2. The method for preparing the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material according to claim 1, characterized in that: The metal salt includes any one of sulfate, chloride or nitrate and hydrates thereof.

3. The method for preparing the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material according to claim 1, characterized in that: The solvent described in step 1 includes any one of anhydrous ethanol, water, and a mixed solution of anhydrous ethanol and water in a volume ratio of 1:

1.

4. The method for preparing the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material according to claim 1, characterized in that: The sufficient stirring and ultrasonic treatment described in step 1 is to stir magnetically for 1 to 4 hours at room temperature and then put it into an ultrasonic cleaning machine for ultrasonication for 1 to 2 hours.

5. The method for preparing the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material according to claim 1, characterized in that: The carbon paper in the step 2 is wetted by any one of dripping with a pipette gun, spraying with an electrostatic spray gun, or soaking.

6. The method for preparing the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material according to claim 1, characterized in that: The vacuum drying described in step 2 is vacuum drying at 80° C. for 12 to 24 hours.

7. The method for preparing the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material according to claim 1, characterized in that: The inert atmosphere described in step 3 includes any one of argon, nitrogen, and argon-hydrogen mixed gas.

8. The method for preparing the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material according to claim 1, characterized in that: The heating rate of the tubular furnace described in step 3 is 1°C / min to 10°C / min.

9. A VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material prepared by the method according to any one of claims 1 to 8.

10. Use of the VZrNbTaWMoCr high entropy nano alloy layer coated carbon fiber composite electrode material as claimed in claim 9 in a negative electrode-free lithium metal battery.

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