A method for preparing a high-entropy MXene composite separator coating

Abstract

The application discloses a preparation method of a high-entropy MXene composite diaphragm coating, which comprises the following steps: in the first step, 2g of HE-MAX phase raw material powder is gradually added into a reaction container containing an HF solution to perform a chemical etching reaction, and meanwhile, the sample is magnetically stirred at 55 DEG C for 72 to 96h; in the second step, the obtained HE-MXene suspension is placed into a centrifugal tube, and the precipitate is collected by high-speed centrifugation, and the deionized water and anhydrous ethanol are repeatedly cleaned until the solution is close to neutral; in the third step, the obtained precipitate is vacuum dried at 60 DEG C for 12h to obtain HE-MXene nanosheet powder; in the fourth step, the HE-MXene and two-dimensional layered material powder are weighed according to a weight ratio of 7:3, and after grinding, they are dissolved into deionized water and stirred to prepare an HE-MXene suspension; in the fifth step, after magnetic stirring is used until the mixed state is reached, vacuum filtration is performed; in the sixth step, the obtained HE-MXene / two-dimensional layered material@PP is placed in a vacuum environment and dried at 40 DEG C for 6h, and finally, the modified diaphragm is cut into a disc with a diameter of 18mm.

Description

Technical Field

[0001] This invention belongs to the field of new energy materials technology, specifically relating to a method for preparing a high-entropy MXene composite membrane coating. Background Technology

[0002] Lithium-sulfur batteries (LSBs), with their high energy density and excellent chemical stability, have become one of the best candidates for high-density energy storage devices to replace traditional lithium-ion batteries. Surprisingly, sulfur, an abundant, inexpensive, and environmentally friendly element, perfectly meets current societal demands for new energy sources. However, regrettably, the polysulfide shuttle effect during charge and discharge, the sluggish redox kinetics of lithium polysulfides (LiPSs), and uncontrollable Li₂S₂ / Li₂S deposition are the main reasons limiting the commercial application of LSBs. Among these, the polysulfide shuttle effect is the most pressing issue.

[0003] To overcome this challenge, early researchers focused on constructing sulfur / carbon composite cathodes, where carbon-based materials act as a conductive network to provide rapid electron transfer and accelerate the redox conversion of LiPSs. Furthermore, significant efforts were devoted to electrolyte composition control, separator / intermediate layer modification and surface treatment, and lithium anode protection. However, most methods fail to address all these aspects simultaneously, making it difficult to optimize the cycle performance of lithium-sulfur batteries. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems and provide a method for preparing a high-entropy MXene composite membrane coating that is simple to process, easy to operate, and capable of strongly capturing LiPSs and accelerating the redox conversion of LiPSs.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a method for preparing a high-entropy MXene composite membrane coating, comprising the following steps:

[0006] S1. Gradually add 2g of HE-MAX phase (TiVNbMoAlC3) raw material powder into a reaction vessel containing 40mL of acid source (≤40%) to carry out chemical etching reaction. At the same time, the sample is magnetically stirred at 55℃ for 72-96h.

[0007] S2. Place the obtained HE-MXene (TiVNbMoC3) suspension into a centrifuge tube and centrifuge at 8000-1000 rpm. Collect the precipitate by high-speed centrifugation. During this period, wash the solution several times with deionized water and anhydrous ethanol until the solution is close to neutral (pH≈7).

[0008] S3. The obtained precipitate was vacuum dried at 60℃ for 12h to finally obtain HE-MXene nanosheet powder.

[0009] S4, HE-MXene, and two-dimensional layered material powder were weighed at a weight ratio of 7:3, thoroughly ground, dissolved in a certain volume of deionized water, and stirred to prepare a solution with a mass concentration of 10 mg·mL⁻¹. -1 HE-MXene suspension;

[0010] S5. After mixing with magnetic stirring, vacuum filtration is performed using a polypropylene (PP) diaphragm as the filter membrane.

[0011] S6. The obtained HE-MXene / two-dimensional layered material@PP was dried at 40°C for 6 hours in a vacuum environment, and finally cut into circular pieces with a diameter of 18 mm to obtain the modified diaphragm required for the experiment.

[0012] Furthermore, the acid source in step S1 includes HF solution and HCl solution.

[0013] Furthermore, the centrifugation time in step S2 is 5 to 10 minutes.

[0014] Furthermore, the drying method in step S3 is freeze drying.

[0015] Furthermore, the stirring time in step S4 is 4 to 6 hours.

[0016] Furthermore, the stirring time in step S5 is 4 to 6 hours.

[0017] Furthermore, in step S6, the weight ratio of HE-MXene to two-dimensional layered material powder is 8:2.

[0018] Furthermore, the two-dimensional layered material in step S6 is one of graphene, boron nitride, molybdenum disulfide, and tungsten disulfide.

[0019] Furthermore, the high-entropy MXene composite membrane coating prepared according to claims 1 to 8 is applied to lithium-sulfur batteries.

[0020] The beneficial effects of this invention are:

[0021] 1. The present invention provides a method for preparing a high-entropy MXene composite membrane coating, which uses hydrofluoric acid chemical etching to obtain HE-MXene. This process is simple, convenient and green and pollution-free, and cleverly combines the advantages of "high entropy" with MXene.

[0022] 2. In this invention, the arrangement and combination of multiple metal atoms leads to electron redistribution, exhibiting high conductivity and enabling rapid interfacial electron transfer. Secondly, under the influence of the cocktail effect, the synergistic enhancement of multiple metals contributes abundant active sites and catalytic activity, facilitating the strong capture and conversion of LiPSs. Furthermore, due to the lattice distortion effect and entropy stabilization effect, the high-entropy internal crystal structure achieves high order, significantly reducing the obstacles to lithium-ion migration. As expected, the prepared HE-MXene / G@PP modified separator not only efficiently adsorbs LiPSs and accelerates the kinetics of polysulfide redox reactions, but also protects the lithium metal anode, providing a new approach for the future commercial development of high-performance lithium-sulfur batteries.

[0023] 3. This invention incorporates "high entropy" into MXene to prepare a HE-MXene composite membrane coating. This functional membrane, under the multiple effects of high entropy, achieves strong capture of LiPSs, accelerates the redox conversion kinetics of LiPSs, and effectively protects the lithium anode. Attached Figure Description

[0024] Figure 1 This is a SEM image and elemental mapping image of HE-MXene prepared according to Example 1 of the preparation method of high-entropy MXene composite membrane coating of the present invention;

[0025] Figure 2 The TEM image, lattice fringes, and electron mapping image of HE-MXene prepared in Embodiment 1 of this invention are shown.

[0026] Figure 3 This is the XRD pattern of HE-MXene prepared in Embodiment 1 of the present invention;

[0027] Figure 4 This is the Fourier transform infrared spectrum of HE-MXene prepared in Embodiment 1 of the present invention;

[0028] Figure 5 These are mechanical property test diagrams of the HE-MXene / G@PP modified separator prepared in Example 1 of this invention;

[0029] Figure 6 This is the UV-Vis spectrum of the HE-MXene / G@PP modified diaphragm prepared in Example 1 of this invention dissolved in Li2S6 solution;

[0030] Figure 7 This is a graph showing the voltage variation of the HE-MXene / G@PP battery prepared in Example 1 of this invention;

[0031] Figure 8This is a graph showing the long-cycle performance of HE-MXene / G@PP prepared in Example 1 of this invention;

[0032] Figure 9 The HE-MXene / G@PP-Li prepared in Example 1 of this invention operates at 10 mA·cm⁻¹. -2 / 10mAh·cm -2 Long-cycle performance diagram of the counter electrode;

[0033] Figure 10 The HE-MXene / G@PP-Li prepared in Example 1 of this invention operates at 10 mA·cm⁻¹. -2 / 1mAh·cm -2 Long-cycle performance diagram of the counter electrode. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0035] Example 1

[0036] like Figure 1 As shown, the present invention provides a method for preparing a high-entropy MXene composite membrane coating, comprising the following steps:

[0037] S1. Gradually add 2g of HE-MAX phase (TiVNbMoAlC3) raw material powder into a reaction vessel containing 40mL of acid source (≤40%) to carry out chemical etching reaction. At the same time, the sample is magnetically stirred at 55℃ for 72-96h.

[0038] In this embodiment, the magnetic stirring time is 96 hours. The acid source used in this step includes HF solution and HCl solution. In this embodiment, the acid source is HF solution.

[0039] S2. Place the obtained HE-MXene (TiVNbMoC3) suspension into a centrifuge tube and centrifuge at 8000-1000 rpm. Collect the precipitate by high-speed centrifugation. During this process, wash the solution several times with deionized water and anhydrous ethanol until the solution is close to neutral (pH≈7). The centrifugation time in this step is 5-10 min.

[0040] S3. The obtained precipitate is vacuum dried at 60℃ for 12 hours to obtain HE-MXene nanosheet powder. In this step, the drying method is freeze drying.

[0041] S4, HE-MXene, and two-dimensional layered material powder were weighed at a weight ratio of 7:3, thoroughly ground, dissolved in a certain volume of deionized water, and stirred to prepare a solution with a mass concentration of 10 mg·mL⁻¹. -1The HE-MXene suspension. The stirring time in this step is 4–6 hours.

[0042] S5. After mixing with magnetic stirring, vacuum filtration is performed using a polypropylene (PP) diaphragm as the filter membrane.

[0043] The stirring time in this step is 4 to 6 hours.

[0044] S6. The obtained HE-MXene / two-dimensional layered material@PP was dried at 40°C for 6 hours in a vacuum environment, and finally cut into circular pieces with a diameter of 18 mm to obtain the modified diaphragm required for the experiment.

[0045] In step S6, the weight ratio of HE-MXene to the two-dimensional layered material powder is 8:2. The two-dimensional layered material in step S6 is one of graphene, boron nitride, molybdenum disulfide, and tungsten disulfide.

[0046] The high-entropy MXene composite membrane coating prepared by this invention is applied to lithium-sulfur batteries.

[0047] Figures 1 to 2 Morphological analysis of HE-MXene prepared in Example 1 Figures 3 to 4 For the phase composition analysis of HE-MXene, Figures 5 to 6 Mechanical properties and adsorption characteristics of HE-MXene / G@PP were analyzed. Figures 7 to 10 Electrochemical performance analysis of HE-MXene / G@PP. Detailed analysis is as follows:

[0048] 1. Morphological analysis:

[0049] like Figure 1 As shown, from Figure 1 As shown in Figure ac, after chemical etching, the Al layer of the HE-MXene phase is effectively removed using van der Waals forces, resulting in a multilayered nanosheet structure that can serve as an ideal container for lithium-ion storage. From the SEM mapping image, it is easy to identify that the five elements Ti, V, Nb, Mo, and C are uniformly distributed on the HE-MXene nanosheets, which helps to form stable chemical bonds with LiPSs, such as... Figure 1 The numbers marked d to i are shown in the diagram.

[0050] Transmission electron microscope images show, as Figure 2 As shown in a to e, acid-treated MXene exhibits a typical layered structure and clear lattice fringes.

[0051] 2. Phase composition analysis:

[0052] exist Figure 3In the X-ray diffraction (XRD) pattern, several strong characteristic peaks disappeared in HE-MXene. Simultaneously, the (002) peak of the HE-MAX phase shifted leftward from 8.56° to 5.50°. This indicates successful exfoliation of the Al layer, further confirming the above analytical results.

[0053] Fourier transform infrared spectroscopy ( Figure 4 This is used to characterize the functional groups and characteristic peaks of the MXene surface. At 1167 cm⁻¹ -1 1538cm -1 CF and C=O appeared respectively. Additionally, 1706cm... -1 The functional group at the site may be related to the metal -C in HE-MXene.

[0054] 3. Mechanical property analysis:

[0055] Figure 5 The HE-MXene / G@PP membrane exhibited good toughness, and the HE-MXene / G modified layer and PP membrane had strong adhesion without delamination.

[0056] 4. Adsorption characteristics analysis:

[0057] To further verify the adsorption effect of HE-MXene / G on LiPSs ( Figure 6 The UV spectra of polysulfide Li2S6 were investigated. After the addition of HE-MXene / G powder, the peak intensity gradually decreased with increasing time. This phenomenon was further confirmed in the inset.

[0058] 5. Electrochemical performance analysis:

[0059] Figure 7 The electrostatic charge / discharge curves of batteries using different separators were tested at a current density of 1C. The initial discharge capacity of HE-MXene / G@PP reached 1069.2 mAh·g. -1 It is far superior to Ti4C3@PP (831.62mAh·g) -1 ) and PP (638.82mAh·g -1 More notably, the voltage gap of HE-MXene / G@PP during the charge / discharge plateau phase is only 0.16V, the lowest among the three battery types.

[0060] To further support the performance advantages of HE-MXene / G@PP over Ti4C3@PP and PP Figure 8 Their long-cycle performance at a high current rate of 1.0C was compared. HE-MXene / G@PP retained 560.5 mAh·g after 400 cycles.-1 Furthermore, the capacity retention rate is 67.6%. It should be noted that the obtained battery performance is quite competitive among current literature on lithium-sulfur batteries using different separators or sandwich layers.

[0061] To evaluate the effect of HE-MXene / G@PP on the long-term cycling stability of lithium metal anodes, we fabricated lithium||lithium symmetric cells. For example... Figure 9 As shown, at 10mA cm -2 / 10mAh cm -2 Under these conditions, it exhibits excellent cycling stability after 2500 hours of cycling, with overpotentials below 15 mV. Even at 10 mA cm⁻¹... -2 / 1mAh cm -2 Compared to Ti4C3@PP and PP, HE-MXene / G@PP still exhibits lower overpotential and better cycling stability. Figure 10 The results show that HE-MXene / G@PP is beneficial for the formation of uniform lithium deposition and good lithium plating / stripping behavior.

[0062] Example 2

[0063] The differences between this embodiment and Embodiment 1 are as follows:

[0064] S1. 2g of HE-MAX phase (TiVNbMoAlC3) raw material powder was gradually added to a reaction vessel containing 40mL of a mixed solution of HCl (≤40%) and 2g of LiF to carry out a chemical etching reaction. Simultaneously, the sample was magnetically stirred at 55℃ for 96h.

[0065] S2. Place the obtained HE-MXene (TiVNbMoC3) suspension into a centrifuge tube and centrifuge at 8000-1000 rpm for 10 min. Collect the precipitate by high-speed centrifugation. During this period, wash the solution several times with deionized water and anhydrous ethanol until the solution is close to neutral (pH≈7).

[0066] S3. The obtained precipitate is vacuum dried at 60℃ for 12h to finally obtain HE-MXene nanosheet powder.

[0067] S4, HE-MXene, and boron nitride powder were weighed at a weight ratio of 7:3. After thorough grinding, they were dissolved in a certain volume of deionized water and stirred for 5 hours to prepare a solution with a mass concentration of 10 mg·mL⁻¹. -1 HE-MXene suspension.

[0068] S5. After stirring with magnetic force for 5 hours until the mixture is mixed, vacuum filtration is performed using a polypropylene (PP) diaphragm as the filter membrane.

[0069] S6. The obtained HE-MXene / BN@PP was dried at 40°C in a vacuum environment for 6 hours, and finally cut into circular pieces with a diameter of 18 mm to obtain the modified diaphragm required for the experiment.

[0070] Example 3

[0071] The differences between this embodiment and Embodiment 1 are as follows:

[0072] S1. Gradually add 2g of HE-MAX phase (TiVNbMoAlC3) raw material powder into a reaction vessel containing 40mL of HF solution (≤40%) to carry out a chemical etching reaction. Simultaneously, the sample is magnetically stirred at 55℃ for 96h.

[0073] S2. Place the obtained HE-MXene (TiVNbMoC3) suspension into a centrifuge tube and centrifuge at 8000-1000 rpm for 5 min. Collect the precipitate by high-speed centrifugation. During this period, wash the solution several times with deionized water and anhydrous ethanol until the solution is close to neutral (pH≈7).

[0074] S3. Vacuum dry the obtained precipitate to finally obtain HE-MXene nanosheet powder.

[0075] S4, HE-MXene, and molybdenum disulfide powder were weighed at a weight ratio of 8:2. After thorough grinding, they were dissolved in a certain volume of deionized water and stirred for 4 hours to prepare a solution with a mass concentration of 10 mg·mL⁻¹. -1 HE-MXene suspension.

[0076] S5. After stirring with magnetic force for 4 hours until the mixture is mixed, vacuum filtration is performed using a polypropylene (PP) diaphragm as the filter membrane.

[0077] S6. The obtained HE-MXene / MoS2@PP was dried at 40℃ in a vacuum environment for 6 hours, and finally cut into round pieces with a diameter of 18mm to obtain the modified diaphragm required for the experiment.

[0078] Example 4

[0079] The differences between this embodiment and Embodiment 1 are as follows:

[0080] S1. Gradually add 2g of HE-MAX phase (TiVNbMoAlC3) raw material powder into a reaction vessel containing 40mL of HF solution (≤40%) to carry out a chemical etching reaction. Simultaneously, the sample is magnetically stirred at 55℃ for 96h.

[0081] S2. Place the obtained HE-MXene (TiVNbMoC3) suspension into a centrifuge tube and centrifuge at 8000-1000 rpm for 8 min. Collect the precipitate by high-speed centrifugation. During this period, wash the solution several times with deionized water and anhydrous ethanol until the solution is close to neutral (pH≈7).

[0082] S3. The obtained precipitate is vacuum dried at 60℃ for 12h to finally obtain HE-MXene nanosheet powder.

[0083] S4, HE-MXene, and tungsten disulfide powder were weighed at a weight ratio of 7:3. After thorough grinding, they were dissolved in a certain volume of deionized water and stirred for 6 hours to prepare a solution with a mass concentration of 10 mg·mL⁻¹. -1 HE-MXene suspension.

[0084] S5. After stirring with magnetic force for 6 hours until the mixture is mixed, vacuum filtration is performed using a polypropylene (PP) diaphragm as the filter membrane.

[0085] S6. The obtained HE-MXene / WS2@PP was dried at 40℃ in a vacuum environment for 6 hours, and finally cut into round pieces with a diameter of 18mm to obtain the modified diaphragm required for the experiment.

[0086] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for preparing a high-entropy MXene composite membrane coating, characterized in that, Includes the following steps: S1. 2 g of HE-MAX phase TiVNbMoAlC3 raw material powder was gradually added to a reaction vessel containing 40 mL of acid source with a concentration ≤40% for chemical etching reaction. At the same time, the sample was magnetically stirred at 55 °C for 72~96 h. S2. Place the obtained HE-MXene, TiVNbMoC3 suspension into a centrifuge tube and centrifuge at 8000~1000 rpm. Collect the precipitate by high-speed centrifugation. During this period, wash the solution several times with deionized water and anhydrous ethanol until the solution is close to neutral (pH≈7). S3. The obtained precipitate was vacuum dried at 60 °C for 12 h to finally obtain HE-MXene nanosheet powder; S4, HE-MXene, and two-dimensional layered material powder were weighed at a weight ratio of 7:3, thoroughly ground, dissolved in a certain volume of deionized water, and stirred to prepare a solution with a mass concentration of 10 mg·mL⁻¹. -1 HE-MXene suspension; S5. After mixing with magnetic stirring, vacuum filtration is performed using a polypropylene (PP) diaphragm as the filter membrane. S6. The obtained HE-MXene / two-dimensional layered material@PP was dried in a vacuum environment at 40 ℃ for 6 h, and finally cut into circular pieces with a diameter of 18 mm to obtain the modified diaphragm required for the experiment. The two-dimensional layered material in step S6 is one of graphene, boron nitride, molybdenum disulfide, and tungsten disulfide.

2. The method for preparing a high-entropy MXene composite membrane coating according to claim 1, characterized in that: The acid source in step S1 includes HF solution and HCl solution.

3. The method for preparing a high-entropy MXene composite membrane coating according to claim 1, characterized in that: In step S2, the centrifugation time is 5-10 min.

4. The method for preparing a high-entropy MXene composite membrane coating according to claim 1, characterized in that: The drying method in step S3 is freeze drying.

5. The method for preparing a high-entropy MXene composite membrane coating according to claim 1, characterized in that: The stirring time in step S4 is 4-6 hours.

6. The method for preparing a high-entropy MXene composite membrane coating according to claim 1, characterized in that: The stirring time in step S5 is 4-6 hours.

7. The method for preparing a high-entropy MXene composite membrane coating according to claim 1, characterized in that: In step S6, the weight ratio of HE-MXene to two-dimensional layered material powder is 8:

2.

8. A method for preparing a high-entropy MXene composite membrane coating according to any one of claims 1 to 7, characterized in that: The high-entropy MXene composite membrane coating prepared by the above method is used in lithium-sulfur batteries.

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