High-entropy nitride film coated carbon fiber composite electrode material and preparation method and application thereof

Abstract

The invention discloses a high-entropy nitride film coated carbon fiber composite electrode material and a preparation method and application thereof, and the preparation method comprises the steps: dissolving five or more metal salt powder into an absolute ethyl alcohol solvent according to the equal molar ratio of metal elements, and obtaining a solution A with the total metal ion concentration of 0.0025-0.1 mol / L; the carbon paper is placed in a plasma cleaning machine to be activated for 10-30 min; the solution A is evenly attached to the carbon paper in the second step through a pipette, the dropwise adding amount is 30-150 [mu] l / cm < 2 >, and composite carbon fibers are obtained and dried in a vacuum drying oven; the composite carbon fiber is placed in a tube furnace filled with nitrogen to be heated to 700-1200 DEG C, the heat preservation time is 0-2 h, and after the composite carbon fiber is cooled to the room temperature along with the furnace, the high-entropy nitride film coated carbon fiber composite electrode material is obtained. By combining the synergistic effect of the carbon fiber and the high-entropy compound, volume expansion and accumulated mechanical stress in the reaction process of the lithium metal battery are effectively relieved, the integrity of an electrode is maintained, a stable SEI film is constructed, and the cycling stability of the battery is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, relates to electrode materials for lithium-ion batteries, and particularly relates to a high-entropy nitride thin film-coated carbon fiber composite electrode material, a preparation method thereof, and an application thereof. Background Art

[0002] As early as the 1970s, scientific research on lithium metal as the anode of lithium batteries had already begun. However, due to the safety and stability problems of lithium metal anodes, such as the short-circuit risk caused by the growth of lithium dendrites, and the unstable solid electrolyte interface (SEI) affecting the cycle life, etc., the technological development of lithium metal batteries once stagnated. In recent years, with the rapid growth of the renewable energy and electric vehicle markets, the demand for high energy density and long cycle life has been increasing day by day, and lithium metal batteries have once again attracted people's attention. Currently, the research on lithium metal batteries is in the process of transitioning from basic research to commercialization. In order to improve the safety and cycle life of lithium metal batteries, researchers have carried out a large number of innovations in electrolytes, anode protective layers, and battery manufacturing processes to inhibit problems such as the growth of lithium dendrites and volume expansion. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a high-entropy nitride thin film-coated carbon fiber composite electrode material, a preparation method thereof, and an application thereof. By combining the synergistic effects of carbon fiber and high-entropy alloy, it can effectively alleviate the volume expansion and accumulated mechanical stress during the reaction process, maintain the integrity of the electrode, and construct a stable SEI film, thereby improving the cycle stability of the battery.

[0004] To achieve the above purpose, the present invention is implemented by adopting the following technical solutions:

[0005] A preparation method of a high-entropy nitride thin film-coated carbon fiber composite electrode material, comprising the following steps:

[0006] Step 1: Add metal salt powders of five or more kinds in an equimolar ratio of their metal elements to an anhydrous ethanol solvent, and stir magnetically and perform ultrasonic treatment until dissolved to obtain solution A with a total metal ion concentration of 0.0025 - 0.1 mol / L;

[0007] Step 2: Place the carbon paper in a plasma cleaner and activate it for 10 - 30 min;

[0008] Step 3: Use a pipette gun to uniformly attach solution A to the carbon paper in Step 2, with a dropping amount of 30 - 150 μl / cm 2 , to obtain composite carbon fiber and dry it in a vacuum oven;

[0009] Step 4: Place the dried composite carbon fiber in Step 3 into a tube furnace filled with nitrogen and heat it from room temperature to 700 - 1200 °C at a heating rate of 1 - 10 °C / min, with a holding time of 0 - 2 h. After cooling to room temperature with the furnace, a composite electrode material with a high-entropy nitride film-coated carbon fiber is obtained.

[0010] The present invention also has the following technical features:

[0011] Preferably, the metal elements in Step 1 include at least 5 of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Mn, Fe, Co, Ni, Cu, and Zn.

[0012] Preferably, the metal salts in Step 1 include any one or a mixture of several of metal nitrates, nitrites, chlorides, sulfates, fluorides, or acetates.

[0013] Preferably, the magnetic stirring time in Step 1 is 0.5 - 2 h.

[0014] Preferably, the ultrasonic treatment time in Step 1 is 0.5 - 2 h.

[0015] Preferably, in Step 3, the temperature of the vacuum oven during drying is 50 - 80 °C, and the drying time is 8 - 24 h.

[0016] The present invention also protects a composite electrode material with a high-entropy nitride film-coated carbon fiber prepared by the method as described above and its application in the negative electrode of a lithium metal battery.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] In the present invention, a high-entropy nitride film (HEN) is loaded on a carbon fiber skeleton. The carbon fiber skeleton can enhance conductivity, reduce the local current density, and slow down the volume expansion of lithium metal; the multi-element mixing with different ionic radii in the high-entropy nitride (HEN) causes lattice distortion, generating a large number of dislocations and defects, resulting in a large number of lithium active sites, improving the lithiophilicity of the carbon fiber, enabling lithium ions to deposit / strip efficiently on the carbon fiber, affecting the uniformity of lithium deposition, effectively alleviating the volume expansion and accumulated mechanical stress during the reaction, thereby maintaining the integrity of the electrode and constructing a stable SEI film, and enhancing the battery cycle stability;

[0019] The present invention has low raw material costs, a simple synthesis method, is green and environmentally friendly, has a high yield, and is conducive to industrial production; the prepared electrode material has a high specific capacitance, good stability, and a long cycle life, is an excellent electrode material, and has good application prospects. Description of the Drawings

[0020] Figure 1SEM image of the (VZrNbMoTaW)N thin film-coated carbon fiber composite electrode material prepared in Example 1;

[0021] Figure 2 EDS image of the (VZrNbMoTaW)N thin film-coated carbon fiber composite electrode material prepared in Example 1;

[0022] Figure 3 XRD pattern of the (VZrNbMoTaW)N thin film-coated carbon fiber composite electrode material prepared in Example 1;

[0023] Figure 4 Full cell performance graph of the (VZrNbMoTaW)N thin film-coated carbon fiber composite electrode material prepared in Example 1 at 0.5C;

[0024] Figure 5 Cycling stability graph of the (VZrNbMoTaW)N thin film-coated carbon fiber composite electrode material prepared in Example 1 applied to lithium-ion batteries;

[0025] Figure 6 Rate performance graph of the (VZrNbMoTaW)N thin film-coated carbon fiber composite electrode material prepared in Example 1 applied to lithium-ion batteries. Detailed implementation manners

[0026] The following further elaborates and explains the specific content of the present invention in conjunction with examples.

[0027] Example 1

[0028] This example provides a preparation method for a high-entropy nitride thin film-coated carbon fiber composite electrode material, including the following steps:

[0029] Step 1: Respectively add 0.01 mmol of MoCl5, NbCl5, WCl6, VCl3, ZrCl4, and TaCl5 into 5 ml of anhydrous ethanol solvent, magnetically stir for 2 h, and ultrasonically stir for 1 h until dissolved to obtain solution A;

[0030] Step 2: Place the carbon paper in a plasma cleaner for activation for 15 min;

[0031] Step 3: Use a pipette to uniformly attach solution A to the carbon paper in Step 2, and the suction volume is 50 μl / cm 2 , to obtain a composite carbon fiber and dry it in a vacuum oven at 80°C for 8 h;

[0032] Step 4: Place the dried composite carbon fiber in Step 3 in a tube furnace filled with nitrogen, heat it to 1000 °C at a heating rate of 2 °C / min, keep it warm for 0.5 h, and obtain the high-entropy nitride film-coated carbon fiber composite electrode material after cooling to room temperature.

[0033] Example 2

[0034] This example provides a preparation method for a high-entropy nitride film-coated carbon fiber composite electrode material, including the following steps:

[0035] Step 1: Add 0.05 mmol of Ti(NO3)4, Cr(NO3)3, Hf(NO3)4, V(NO3)3, and Zr(NO3)4 to 10 ml of anhydrous ethanol solvent, stir magnetically for 2 h and ultrasonically for 1 h until dissolved to obtain Solution A;

[0036] Step 2: Place the carbon paper in a plasma cleaner and activate it for 15 min;

[0037] Step 3: Use a pipette to uniformly aspirate Solution A and attach it to the carbon paper in Step 2, with an aspiration volume of 80 μl / cm 2 , obtain the composite carbon fiber and dry it in a vacuum oven at 80 °C for 10 h;

[0038] Step 4: Place the dried composite carbon fiber in Step 3 in a tube furnace filled with nitrogen, heat it to 900 °C at a heating rate of 3 °C / min, keep it warm for 1 h, and obtain the high-entropy nitride film-coated carbon fiber composite electrode material after cooling to room temperature.

[0039] Example 3

[0040] This example provides a preparation method for a high-entropy nitride film-coated carbon fiber composite electrode material, including the following steps:

[0041] Step 1: Add 0.1 mmol of MoF5, NbF5, WF6, VF3, MnF2, and CrF to 20 ml of anhydrous ethanol solvent, stir magnetically for 1 h and ultrasonically for 0.5 h until dissolved to obtain Solution A;

[0042] Step 2: Place the carbon paper in a plasma cleaner and activate it for 10 min;

[0043] Step 3: Use a pipette to uniformly aspirate Solution A and attach it to the carbon paper in Step 2, with an aspiration volume of 40 μl / cm 2 , obtain the composite carbon fiber and dry it in a vacuum oven at 60 °C for 15 h;

[0044] Step 4: Place the dried composite carbon fiber in Step 3 in a tube furnace filled with nitrogen, heat it to 700 °C at a heating rate of 1 °C / min, hold for 0.5 h, and obtain the high-entropy nitride thin film-coated carbon fiber composite electrode material after cooling to room temperature.

[0045] Example 4

[0046] This example provides a preparation method for a high-entropy nitride thin film-coated carbon fiber composite electrode material, including the following steps:

[0047] Step 1: Add 0.01 mmol of MoCl5, NbCl5, WCl6, VCl3, ZrCl4, and TaCl5 to 20 ml of anhydrous ethanol solvent, stir magnetically for 1 h and ultrasonically for 2 h until dissolved to obtain Solution A;

[0048] Step 2: Place the carbon paper in a plasma cleaner and activate it for 20 min;

[0049] Step 3: Use a pipette to uniformly aspirate Solution A onto the carbon paper in Step 2, with an aspiration volume of 30 μl / cm 2 , obtain the composite carbon fiber and dry it in a vacuum oven at 80 °C for 8 h;

[0050] Step 4: Place the dried composite carbon fiber in Step 3 in a tube furnace filled with nitrogen, heat it to 800 °C at a heating rate of 5 °C / min, hold for 0 h, and obtain the high-entropy nitride thin film-coated carbon fiber composite electrode material after cooling to room temperature.

[0051] Example 5

[0052] This example provides a preparation method for a high-entropy nitride thin film-coated carbon fiber composite electrode material, including the following steps:

[0053] Step 1: Add 0.1 mmol of Mo(NO2)5, Nb(NO2)5, W(NO2)6, V(NO2)3, Fe(NO2)3, Co(NO3)2, and Ni(NO3)2 to 5 ml of anhydrous ethanol solvent, stir magnetically for 0.5 h and ultrasonically for 2 h until dissolved to obtain Solution A;

[0054] Step 2: Place the carbon paper in a plasma cleaner and activate it for 25 min;

[0055] Step 3: Use a pipette to uniformly aspirate Solution A onto the carbon paper in Step 2, with an aspiration volume of 60 μl / cm 2 , obtain the composite carbon fiber and dry it in a vacuum oven at 80 °C for 8 h;

[0056] Step 4: Place the dried composite carbon fiber in Step 3 in a tube furnace filled with nitrogen and heat it to 1000 °C at a heating rate of 8 °C / min. Keep it at this temperature for 1 h. After cooling to room temperature, a composite electrode material with a high-entropy nitride film-coated carbon fiber is obtained.

[0057] Example 6

[0058] This example provides a method for preparing a composite electrode material with a high-entropy nitride film-coated carbon fiber, which includes the following steps:

[0059] Step 1: Add 0.01 mmol of C8H 12 Mo2O8, Nb(CH3COO)5, WCl6, VCl3, ZrCl4, TaCl5, CrCl3 to 10 ml of anhydrous ethanol solvent, stir magnetically for 0.5 h, and ultrasonically for 2 h until dissolved to obtain Solution A;

[0060] Step 2: Place the carbon paper in a plasma cleaner and activate it for 30 min;

[0061] Step 3: Use a pipette to suck Solution A and evenly attach it to the carbon paper in Step 2. The suction amount is 100 μl / cm 2 , obtain the composite carbon fiber and dry it in a vacuum oven at 80 °C for 8 h;

[0062] Step 4: Place the dried composite carbon fiber in Step 3 in a tube furnace filled with nitrogen and heat it to 1100 °C at a heating rate of 5 °C / min. Keep it at this temperature for 1.5 h. After cooling to room temperature, a composite electrode material with a high-entropy nitride film-coated carbon fiber is obtained.

[0063] Example 7

[0064] This example provides a method for preparing a composite electrode material with a high-entropy nitride film-coated carbon fiber, which includes the following steps:

[0065] Step 1: Add 0.1 mmol of MoCl5, WCl6, VCl3, CuSO4, ZnSO4, TaCl5, CrCl3 to 10 ml of anhydrous ethanol solvent, stir magnetically for 1 h, and ultrasonically for 1 h until dissolved to obtain Solution A;

[0066] Step 2: Place the carbon paper in a plasma cleaner and activate it for 15 min;

[0067] Step 3: Use a pipette to suck Solution A and evenly attach it to the carbon paper in Step 2. The suction amount is 150 μl / cm 2 , obtain the composite carbon fiber and dry it in a vacuum oven at 50 °C for 24 h;

[0068] Step 4: Place the dried composite carbon fiber in Step 3 into a tubular furnace filled with nitrogen and heat it to 1200 °C at a heating rate of 10 °C / min for a holding time of 2 h. After cooling to room temperature, a composite electrode material with a high-entropy nitride film-coated carbon fiber is obtained.

[0069] The summary is as follows:

[0070] 1 Morphology

[0071] Figure 1 Figure 10 is a SEM image of the (VZrNbMoTaW)N film-coated carbon fiber composite electrode material prepared in Example 1. It can be observed from the SEM image that (VZrNbMoTaW)N grows uniformly on the surface of the carbon fiber. In addition, Figure 2 Figure 11 is an EDS image of the (VZrNbMoTaW)N high-entropy nitride / carbon fiber composite material prepared in Example 1. Figure 2 It reveals the uniform distribution of V, Zr, Nb, Mo, Ta, and W elements throughout the carbon fiber.

[0072] 2 Composition

[0073] Figure 3 Figure 21 shows the XRD diffraction peaks of the (VZrNbMoTaW)N film-coated carbon fiber composite electrode material prepared in Example 1. As Figure 3 shown, the three diffraction peaks of the X-ray diffraction (XRD) of this material correspond to the (111), (200), and (220) planes of the FCC phase, respectively.

[0074] 3 Electrochemical performance

[0075] A full cell based on the negative electrode and LFP positive electrode prepared in Example 1 and a half cell with Li as the positive electrode were assembled.

[0076] Figure 4 Figure 33 shows the performance graph of the full cell with the (VZrNbMoTaW)N-coated carbon fiber composite electrode material prepared in Example 1 at a current density of 0.5C. As Figure 4 shown, a full cell based on the negative electrode and LFP positive electrode prepared in Example 1 has a high capacity retention rate after 200 cycles at a current density of 0.5C.

[0077] Figure 5 Figure 39 shows the cycling performance graph of the half cell with the (VZrNbMoTaW)N-coated carbon fiber composite material prepared in Example 1 at a current density of 5 mA cm -2 and a specific capacity of 1 mAh cm -2 conditions. As Figure 5 shown, the battery still maintains stable performance after 200 cycles and can uniformly guide lithium deposition.

[0078] Figure 6 Rate performance graph of the full cell of the (VZrNbMoTaW)N-coated carbon fiber composite prepared in Example 1 at 0.1C - 3C. As Figure 6 shown, it can still recover after high rate and has good rate retention ability.

[0079] Those of ordinary skill in the art will realize that the embodiments described herein are to assist the reader in understanding the principles of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. The metal elements in the high-entropy nitride of the present invention can also be combinations of various other metal elements given in the technical solution. Those of ordinary skill in the art can make various other specific deformations and combinations that do not depart from the essence of the present invention based on these technical revelations disclosed in the present invention, and these deformations and combinations are still within the scope of protection of the present invention.

Claims

1. A method for preparing a high entropy nitride film coated carbon fiber composite electrode material, characterized in that: The steps include: Step 1, adding five or more metal salt powders in anhydrous ethanol solvent in an equal molar ratio of their metal elements, stirring magnetically and treating ultrasonically until dissolved to obtain a solution A with a total metal ion concentration of 0.0025 to 0.1 mol / L; Step 2: Activate the carbon paper in a plasma cleaning machine for 10 to 30 minutes; Step 3: Use a pipette to evenly adhere solution A to the carbon paper in step 2, with a drop amount of 30-150 μl / cm 2 , obtaining the composite carbon fiber and drying it in a vacuum oven; Step 4: Place the composite carbon fiber dried in step 3 in a tubular furnace filled with nitrogen and heat it from room temperature to 700-1200°C at a heating rate of 1-10°C / min for 0-2h. After cooling to room temperature in the furnace, a high-entropy nitride film-coated carbon fiber composite electrode material is obtained.

2. The method for preparing a high entropy nitride film-coated carbon fiber composite electrode material according to claim 1, characterized in that: The metal elements described in step 1 include at least 5 of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Mn, Fe, Co, Ni, Cu and Zn.

3. The method for preparing a high entropy nitride film-coated carbon fiber composite electrode material according to claim 1, characterized in that: The metal salt described in step 1 includes any one of metal nitrates, nitrites, chlorides, sulfates, fluorides or acetates, or a mixture of several of them.

4. The method for preparing a high entropy nitride film-coated carbon fiber composite electrode material according to claim 1, characterized in that: The magnetic stirring time described in step 1 is 0.5 to 2 hours.

5. The method for preparing a high entropy nitride film-coated carbon fiber composite electrode material according to claim 1, characterized in that: The ultrasonic treatment time described in step 1 is 0.5 to 2 hours.

6. The method for preparing a high entropy nitride film-coated carbon fiber composite electrode material according to claim 1, characterized in that: In the step 3, the temperature of the vacuum oven during drying is 50 to 80° C., and the drying time is 8 to 24 hours.

7. A high entropy nitride film-coated carbon fiber composite electrode material prepared by the method according to any one of claims 1 to 6.

8. Use of the high entropy nitride film coated carbon fiber composite electrode material as claimed in claim 7 in the negative electrode of a lithium metal battery.

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