Preparation methods and applications of MXene-derived single-atom catalysts assisted by ionic liquids
By synthesizing MXene-derived single-atom catalysts with the assistance of ionic liquids, the problem of polysulfide shuttle effect in lithium-sulfur batteries was solved, thereby improving the electrochemical performance and cycle stability of lithium-sulfur batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INSTITUTE OF TECHNOLOGY (SHENZHEN) (INSTITUTE OF SCIENCE AND TECHNOLOGY INNOVATION HARBIN INSTITUTE OF TECHNOLOGY SHENZHEN)
- Filing Date
- 2024-11-25
- Publication Date
- 2026-05-26
Smart Images
Figure CN122076479A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrochemical technology of new energy materials, specifically relating to a method for preparing and applying an ionic liquid-assisted synthesis of MXene-derived single-atom catalysts. Background Technology
[0002] With the continuous development of science and technology, the demand for high-energy-density battery systems is increasing dramatically. Therefore, developing a new generation of inexpensive and efficient batteries is urgently needed. Lithium-sulfur batteries using elemental sulfur or sulfur-containing compounds as the positive electrode have a capacity of 2600 Wh / kg. -1 Theoretical energy density and 1675 mAh g -1 Sulfur has attracted much attention due to its theoretical specific capacity. At the same time, sulfur has advantages such as low price, abundant reserves, and environmental friendliness, making it suitable for the current needs of new energy vehicles and large-scale energy storage.
[0003] Although lithium-sulfur batteries have significant advantages in terms of specific energy and cost, some key issues still need to be addressed, including lithium dendrites, lithium sulfide passivation layers, and a severe "shuttle effect." The severe shuttle effect and slow reaction kinetics of polysulfides (LPS) are the main reasons for the rapid capacity decay of lithium-sulfur batteries.
[0004] To address the aforementioned issues, researchers primarily improve the electrochemical performance of lithium-sulfur batteries by designing modified membranes. However, simple adsorption by modified membranes cannot fundamentally eliminate polysulfide shuttling. Improving reaction kinetics is key to resolving polysulfide shuttling. In contrast, using catalysts to improve the sulfur-supported structure is a simple and effective method.
[0005] Single-atom catalysts (SACs) are catalysts in which active atoms are isolated one by one using a matrix support material. When single-atom catalysts are used for membrane modification, they not only facilitate the adsorption of lithium polysulfides, but also bind to S, weakening the S-S bonds in chain-like lithium polysulfides, thereby promoting the decomposition of LPS or Li2S and facilitating redox reactions during charge and discharge processes. Summary of the Invention
[0006] One objective of this invention is to address the problems mentioned above by providing a catalyst that can effectively suppress the shuttle effect and improve the electrochemical performance of lithium-sulfur batteries.
[0007] Another object of the present invention is to provide the application of the above-described catalyst.
[0008] In a first aspect, the present invention provides a method for preparing MXene-derived single-atom catalysts assisted by ionic liquids, the method comprising the following steps:
[0009] (1) Synthesis of NBF-Ni-LDH / Mo2CT x :
[0010] Ni(NO3)2·6H2O, urea, C6H8O7·H2O, 1-ethyl-3-methylimidazolium tetrafluoroborate and Mo2CT x Add the mixture to deionized water, mix thoroughly, then heat the mixture, wash with ethanol and deionized water, and dry to obtain NBF-Ni-LDH / Mo2CT. x ;
[0011] (2) Synthesis of NBF-NiSe2 / Mo2CT x The NBF-Ni-LDH / Mo2CT x The product NBF-NiSe2 / Mo2CT was obtained by sintering with Se powder. x ;
[0012] (3) Synthesis of Pt / NBF-NiSe2 / Mo2CT x : PtCl4 and NBF-NiSe2 / Mo2CT x The sample was placed in ethanol, stirred, and dried to obtain a sample. The sample was then sintered, washed with ethanol, and dried overnight to obtain the single-atom catalyst Pt / NBF-NiSe2 / Mo2CT. x .
[0013] In a preferred embodiment, the proportions of each raw material component in step (1) are as follows: Ni(NO3)2·6H2O 360mg, urea 500mg, C6H8O7·H2O 0.05g, 1-ethyl-3-methylimidazolium tetrafluoroborate 1mL, Mo2CT x 0.1g, 60mL of deionized water; the heating temperature of the mixed solution in step (1) is 150℃, the heating time is 12 hours, the drying temperature is 50-70℃, and the drying time is 12-24 hours.
[0014] In a preferred embodiment, the proportion of each raw material component in step (2) is: NBF-Ni-LDH / Mo2CT x 100 mg of selenium powder and 400 mg of selenium powder were used in the sintering atmosphere of 95% Ar / 5% H2, with a heating rate of 10 °C / min. -1 The sintering temperature is 350℃ and the holding time is 1 hour.
[0015] In a preferred embodiment, the proportions of each raw material component in step (3) are: PtCl4 30mg, NBF-NiSe2 / Mo2CT x50 mg, 30 mL ethanol; sintering atmosphere: 95% Ar / 5% H2, heating rate: 2 °C / min -1 The sintering temperature is 300℃ and the holding time is 1 hour.
[0016] Secondly, the present invention provides an ionic liquid-assisted synthesis of MXene-derived single-atom catalysts prepared by the above method.
[0017] Thirdly, the present invention provides the application of the ionic liquid-assisted synthesis of MXene-derived single-atom catalysts in the preparation of battery cathodes.
[0018] Fourthly, this invention provides the application of the ionic liquid-assisted synthesis of MXene-derived single-atom catalysts in the preparation of lithium-sulfur batteries.
[0019] Fifthly, the present invention provides a sulfur-carbon composite cathode comprising the ionic liquid-assisted synthesis of MXene-derived single-atom catalyst.
[0020] Preferably, the ionic liquid-assisted synthesis of the MXene-derived single-atom catalyst is formed on the surface of the positive electrode as a modification layer. Preferably, the modification layer further comprises sulfur, a binder, and a conductive agent, wherein the binder is preferably PVDF (polyvinylidene fluoride), and the conductive agent is preferably Super P (conductive carbon black).
[0021] Preferably, the sulfur-carbon composite cathode is a sulfur-carbon cathode, and the mass ratio of the MXene-derived single-atom catalyst synthesized with ionic liquid assistance to sulfur is 3:7.
[0022] The positive electrode sheet can be obtained by first impregnating it with active sulfur using a melt diffusion method, then mixing it with PVDF, Super P and NMP, coating it onto aluminum foil and drying it.
[0023] Preferably, the mass ratio of the sulfur-loaded ionic liquid-assisted synthesis of MXene-derived single-atom catalyst, binder, and conductive agent is 8:1:1.
[0024] In a sixth aspect, the present invention provides a lithium-sulfur battery comprising the aforementioned sulfur-carbon composite positive electrode. The lithium-sulfur battery may further include a separator, a lithium negative electrode, and an electrolyte.
[0025] Ionic liquids (ILs), composed of organic cations and inorganic anions, possess advantages such as low cost, eco-friendliness, abundance of heteroatoms, good solubility, and the ability to coordinate with metal ions, making them suitable precursors for catalyst preparation. In the preparation of single-atom MNC catalysts using ILs, firstly, ILs can serve as a heteroatom source, providing elements such as nitrogen, phosphorus, and boron. These heteroatoms with lone pairs of electrons have strong coordination capabilities and can anchor metal single atoms. Secondly, the incorporation of pyridine nitrogen and pyrrole nitrogen derived from ionic liquids can increase the defect density of carbon materials, providing strong anchoring sites for LPS, thereby effectively mitigating the shuttle effect. This invention synthesizes NFB-MXene with the assistance of ionic liquids, subsequently introduces metal single atoms, and applies it to the modification of sulfur-carbon composite electrodes in lithium-sulfur batteries. The introduced metal single-atom catalyst can effectively alleviate the "shuttle effect" in lithium-sulfur batteries, promote the conversion of polysulfides, improve the utilization rate of active materials, and enhance battery cycle performance and stability.
[0026] Compared with the prior art, the present invention has the following beneficial effects:
[0027] (1) This invention utilizes BMImBF4 ionic liquid to assist MXene. Ionic liquid doping not only introduces heteroatoms such as N, F, and B, but also effectively reduces the size of MXene and significantly increases its outer surface area, thus allowing for higher metal atom doping. Subsequently, Se is introduced through high-temperature pyrolysis. The monodisperse metal atoms exhibit very high catalytic activity towards polysulfides, enabling efficient utilization of polysulfides dissolved from the cathode. This greatly improves the utilization rate of active materials, significantly suppresses the shuttle effect, and achieves a high-performance lithium-sulfur battery.
[0028] (2) The single-atom catalyst Pt / NBF-NiSe2 / Mo2CT prepared in this invention x When applied to the cathode modification of lithium-sulfur batteries, it exhibits a significant catalytic conversion effect on polysulfides generated in lithium-sulfur batteries. At 0.2C, the initial charge-discharge specific capacity of the lithium-sulfur battery reaches 1282.3 mAh / g, demonstrating high discharge capacity and excellent cycle stability and rate performance; the initial discharge specific capacity and capacity retention are both higher than those of the control battery. Regarding battery impedance data, the Pt / NBF-NiSe2 / Mo2CT method of this invention... x The lithium-sulfur batteries prepared with the modified cathode all exhibited lower impedances than the control batteries. Furthermore, in redox kinetic tests, the lithium-sulfur battery corresponding to this invention showed the smallest peak potential difference in the CV curve, indicating a significant improvement in redox kinetics. Attached Figure Description
[0029] 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.
[0030] Figure 1 For Pt / NBF-NiSe2 / Mo2CT according to Embodiment 1 of the present invention x SEM images (a) and Pt / NBF-NiSe2 / Mo2CT x TEM image (c), Pt / NiSe2 / Mo2CT of Comparative Example 1 x SEM image (b) and Pt / NiSe2 / Mo2CT x TEM image (d).
[0031] Figure 2 The cyclic voltammetry curves are for lithium-sulfur batteries according to Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention.
[0032] Figure 3 Impedance diagrams of lithium-sulfur batteries according to Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention.
[0033] Figure 4 The graph shows the 0.2C cycle performance of lithium-sulfur batteries according to Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention.
[0034] Figure 5 The diagram shows different rate capability diagrams of lithium-sulfur batteries according to Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Detailed Implementation
[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the following embodiments are only for illustrating the present invention and not for limiting the present invention. Unless otherwise specified, the chemical reagents, instruments, etc. used in the embodiments are well known to those skilled in the art and can be obtained through commercial channels.
[0036] Example 1
[0037] I. Preparation of MXene-derived single-atom catalyst Pt / NBF-NiSe2 / Mo2CT assisted by ionic liquid x The specific steps are as follows:
[0038] (1) Synthesis of NBF-Ni-LDH / Mo2CT x
[0039] Mix 360 mg Ni(NO3)2·6H2O, 500 mg urea, 0.05 g C6H8O7·H2O (citric acid monohydrate), 1 mL 1-ethyl-3-methylimidazolium tetrafluoroborate (BMImBF4), and 0.1 g Mo2CT. x (Beike Nano, catalog number BK2020103108-04) was added to 60 mL of deionized water and mixed thoroughly. The mixture was then heated at 150 °C for 12 hours. Next, it was washed at least twice with ethanol (high purity, water content ≤0.2% v / v) and deionized water, and then dried at 70 °C (or within the range of 50-70 °C) for 24 hours (or within the range of 12-24 hours) to obtain NBF-Ni-LDH / Mo2CT. x .
[0040] (2) Synthesis of NBF-NiSe2 / Mo2CT x
[0041] 100mg of the above NBF-Ni-LDH / Mo2CT x A porcelain boat containing 400 mg of Se powder (78.96 MW) was placed downstream of a quartz tube furnace, while another porcelain boat containing 400 mg of Se powder (78.96 MW) was placed upstream. The furnace was in an Ar / H2 atmosphere (Ar 95% / H2 5% (volume ratio)) at 10 °C for 1 min. -1 The temperature was increased to 350℃ and held for 1 hour for sintering to obtain the target product NBF-NiSe2 / Mo2CT. x .
[0042] (3) Synthesis of Pt / NBF-NiSe2 / Mo2CT x Catalyst composite materials
[0043] 30 mg PtCl4 and 50 mg of the above NBF-NiSe2 / Mo2CT were added. x The sample was added to 30 mL of ethanol (98% v / v), stirred for 1 hour, and then dried in an oven at 70 °C for 6 hours to obtain the sample. Then, 50 mg of the sample was placed in a tube furnace and heated at 2 °C for 1 minute in an Ar / H2 atmosphere (Ar 95% / H2 5% (v / v)). -1 The temperature was increased to 300℃ and held for 1 hour for sintering. Finally, after the furnace cooled to room temperature, the sample was washed at least twice with ethanol (high purity, water content ≤0.2% v / v) and dried at 80℃ overnight to obtain the single-atom catalyst material Pt / NBF-NiSe2 / Mo2CT. x .
[0044] II. Preparation of the sulfur-carbon cathode, the specific steps are as follows:
[0045] Sulfur-carbon composite materials were prepared by melt diffusion method (sulfur and catalyst were ground and mixed, and then reacted at 155°C for 12 hours in a hydrothermal reactor under inert gas protection). The sulfur reacted with the aforementioned Pt / NBF-NiSe2 / Mo2CT. x With a mass ratio of 7:3, this sulfur-carbon composite material is named S@Pt / NBF-NiSe2 / Mo2CT. x The obtained sulfur-carbon composite material, Super-P (conductive carbon black), and PVDF (polyvinylidene fluoride) were mixed in a mass ratio of 8:1:1, using NMP (N-methylpyrrolidone) as a solvent, and mixed evenly by hand grinding. The slurry was then coated onto carbon-coated aluminum foil using a doctor blade with a blade height of 150 μm. The electrode was placed in a vacuum oven and dried at 50°C for 12 hours. After drying, a lithium-sulfur battery positive electrode was prepared, with a sulfur loading of approximately 1.5-2 mg / cm³. -2 .
[0046] III. Battery fabrication, the steps are as follows:
[0047] (1) Place the positive electrode shell on the glass plate;
[0048] (2) Use tweezers to place the pad and the positive electrode into the positive electrode shell in sequence, with the positive electrode in the center;
[0049] (3) Use a dropper or syringe to draw up electrolyte and wet the surface of the positive electrode;
[0050] (4) Clamp the diaphragm and cover the positive electrode plate;
[0051] (5) Use a dropper or syringe to draw up electrolyte again and wet the diaphragm surface;
[0052] (6) Pick up the lithium negative electrode sheet and place it in the center of the separator;
[0053] (7) Clamp the steel sheet and place it on the lithium negative electrode, ensuring strict alignment;
[0054] (8) Clamp the spring sheet and place it on the steel sheet, ensuring strict alignment;
[0055] (9) Use tweezers to pick up the negative electrode shell and cover it to assemble a button cell (the contents of O2 and H2O are both less than 0.01ppm).
[0056] Comparative Example 1
[0057] I. Preparation of Pt / NiSe2 / Mo2CT x The specific steps are as follows:
[0058] (1) Synthesis of Ni-LDH / Mo2CT x
[0059] 360mg Ni(NO3)2·6H2O, 500mg urea, C6H8O7·H2O (0.05g) and Mo2CT x (0.1 g) was added to 60 mL of deionized water and mixed thoroughly. The mixture was then heated at 150 °C for 12 hours. The solution was then washed at least twice with ethanol and deionized water, and dried at 70 °C for 24 hours to obtain Ni-LDH / Mo2CT. x .
[0060] (2) Synthesis of NiSe2 / Mo2CT x
[0061] 100mg Ni-LDH / Mo2CT x A ceramic boat containing 400 mg Se powder (78.96 MW) was placed downstream of a quartz tube furnace, while another ceramic boat containing 400 mg Se powder (78.96 MW) was placed upstream. The furnace was in an Ar / H2 atmosphere (Ar 95% / H2 5% (volume ratio)) at 10 °C for 1 min. -1 After heating the product to 350℃ and holding it there for 1 hour, the target product NiSe2 / Mo2CT was obtained. x .
[0062] (3) Synthesis of Pt / NiSe2 / Mo2CT x Composite materials
[0063] 30 mg PtCl4 and 50 mg NiSe2 / Mo2CT x The sample was added to 30 mL of ethanol (98% v / v), stirred for 1 hour, and then dried in an oven at 70 °C for 6 hours to obtain the sample. Then, 50 mg of the sample was placed in a tube furnace and dried at 2 °C for 1 minute in an Ar / H2 atmosphere (Ar 95% / H2 5% (volume ratio)). -1 The temperature was increased to 300℃ and held for 1 hour. Finally, after the furnace cooled to room temperature, the sample was washed several times with ethanol and dried overnight at 80℃ to obtain Pt / NiSe2 / Mo2CT. x Composite materials.
[0064] II. Preparation of Sulfur-Carbon Cathode
[0065] Sulfur-carbon composite materials were prepared by melt diffusion method (155℃, 12 hours), with sulfur reacting with Pt / NiSe2 / Mo2CT. x With a mass ratio of 7:3, this sulfur-carbon composite material is named S@Pt / NiSe2 / Mo2CT. xThe obtained sulfur-carbon composite material, Super-P, and PVDF were mixed in a mass ratio of 8:1:1, using NMP (N-methylpyrrolidone) as a solvent, and then mixed uniformly by hand grinding. The slurry was then coated onto carbon-coated aluminum foil using a doctor blade with a blade height of 150 μm. The electrode was then dried in a vacuum oven at 50°C for 12 hours. After drying, a lithium-sulfur battery positive electrode was prepared, with a sulfur loading of approximately 1.5-2 mg / cm³. -2 .
[0066] III. Battery fabrication, the steps are as follows:
[0067] (1) Place the positive electrode shell on the glass plate;
[0068] (2) Use tweezers to place the pad and the positive electrode into the positive electrode shell in sequence, with the positive electrode in the center;
[0069] (3) Use a dropper or syringe to draw up electrolyte and wet the surface of the positive electrode;
[0070] (4) Clamp the diaphragm and cover the positive electrode plate;
[0071] (5) Use a dropper or syringe to draw up electrolyte again and wet the diaphragm surface;
[0072] (6) Pick up the lithium negative electrode sheet and place it in the center of the separator;
[0073] (7) Clamp the steel sheet and place it on the lithium negative electrode, ensuring strict alignment;
[0074] (8) Clamp the spring sheet and place it on the steel sheet, ensuring strict alignment;
[0075] (9) Use tweezers to pick up the negative electrode shell and cover it to assemble a button cell (the contents of O2 and H2O are both less than 0.01ppm).
[0076] Comparative Example 2
[0077] The steps for preparing MWCNTs (multi-walled carbon nanotubes) cathodes are as follows:
[0078] I. Preparation of sulfur-carbon cathode, the steps are as follows:
[0079] Sulfur-carbon composite materials were prepared by melt diffusion method (155℃, 12 hours). The mass ratio of elemental sulfur to multi-walled carbon nanotubes (MWCNTs) (3-15 nm diameter, 18-25 μm length, 99% purity) was 3:1. This sulfur-carbon composite material was named S@MWCNTs. The obtained sulfur-carbon composite material, Super-P, and PVDF were mixed in a mass ratio of 8:1:1 using NMP (N-methylpyrrolidone) as solvent and mixed uniformly by hand grinding. The slurry was then coated onto carbon-coated aluminum foil using a doctor blade with a blade height of 150 μm. The electrode was placed in a vacuum oven and dried at 50℃ for 12 hours. After drying, a lithium-sulfur battery positive electrode was prepared with a sulfur loading of approximately 1.0-1.5 mg / cm³. -2 .
[0080] II. Battery fabrication, the steps are as follows:
[0081] (1) Place the positive electrode shell on the glass plate;
[0082] (2) Use tweezers to place the pad and the positive electrode into the positive electrode shell in sequence, with the positive electrode in the center;
[0083] (3) Use a dropper or syringe to draw up electrolyte and wet the surface of the positive electrode;
[0084] (4) Clamp the diaphragm and cover the positive electrode plate;
[0085] (5) Use a dropper or syringe to draw up electrolyte again and wet the diaphragm surface;
[0086] (6) Pick up the lithium negative electrode sheet and place it in the center of the separator;
[0087] (7) Clamp the steel sheet and place it on the lithium negative electrode, ensuring strict alignment;
[0088] (8) Clamp the spring sheet and place it on the steel sheet, ensuring strict alignment;
[0089] (9) Use tweezers to pick up the negative electrode shell and cover it to assemble a button cell (the contents of O2 and H2O are both less than 0.01ppm).
[0090] The composite materials of Example 1 and Comparative Example 1 were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the results are as follows: Figure 1 As shown. Figure 1 A Pt / NBF-NiSe2 / Mo2CT according to Embodiment 1 of the present invention is shown. x SEM images (a) and Pt / NBF-NiSe2 / Mo2CT x TEM image (c), Pt / NiSe2 / Mo2CT of Comparative Example 1 xSEM image (b) and Pt / NiSe2 / Mo2CT x TEM image (d). For example... Figure 1 As shown, the Pt / NBF-NiSe2 / Mo2CT of Embodiment 1 of the present invention... x The composite material has a flower-shaped morphology and a large active surface area.
[0091] The electrical performance of the lithium-sulfur batteries from Example 1, Comparative Example 1, and Comparative Example 2 was measured. Figures 2 to 5 The electrical measurement results of lithium-sulfur batteries in each example are shown.
[0092] Figure 2 The cyclic voltammograms are for lithium-sulfur batteries according to Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Figure 2 As shown, Example 1 uses Pt / NBF-NiSe2 / Mo2CT x The lithium-sulfur battery with sulfur-loaded cathode exhibited higher reduction voltage (2.285 V and 2.015 V) and lower oxidation voltage (2.407 V), as well as a higher redox peak current. This indicates that the Pt / NBF-NiSe2 / Mo2CT synthesized via BMImBF4 ionic liquid... x It promotes the catalytic conversion of polysulfides and significantly improves redox kinetics.
[0093] Figure 3 Impedance diagrams of lithium-sulfur batteries according to Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention are shown. Figure 3 As shown, the impedance of the lithium-sulfur battery in Example 1 is less than that of the lithium-sulfur batteries in Comparative Examples 1 and 2.
[0094] Figure 4 The graph shows the 0.2C cycle performance of lithium-sulfur batteries according to Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Figure 4 As shown, the Pt / NBF-NiSe2 / Mo2CT of Example 1 x The lithium-sulfur battery, with sulfur-loaded cathode, has an initial discharge specific capacity of 1282.3 mAh / g at 0.2C rate and still has a specific capacity of 766.3 mAh / g after 300 cycles, which is stronger than Comparative Example 1 and Comparative Example 2.
[0095] Figure 5 This is a graph showing the different rate capabilities of lithium-sulfur batteries according to Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Figure 5 As shown, the Pt / NBF-NiSe2 / Mo2CT of Example 1 x Lithium-sulfur batteries, used as sulfur-loaded cathodes, exhibit superior rate performance.
[0096] As can be seen from the above results, this invention utilizes BMImBF4 ionic liquid to assist in the synthesis of MXene precursors, and then uniformly disperses single-atom Pt and Se metals in the MXene material derivative to prepare the ionic liquid-assisted synthesis of MXene-derived single-atom catalyst material Pt / NBF-NiSe2 / Mo2CT. x The method of this invention is simple and controllable. When a single-atom catalyst material is applied to the positive electrode of a lithium-sulfur battery, it can effectively alleviate the "shuttle effect" of polysulfides in the lithium-sulfur battery, catalyze the conversion of polysulfides, promote the redox reaction kinetics of the lithium-sulfur battery during charge and discharge, thereby improving the battery's discharge capacity and cycle stability.
Claims
1. A method for preparing an ionic liquid-assisted synthesis of MXene-derived single-atom catalysts, characterized in that, The method includes the following steps: (1) Synthesis of NBF-Ni-LDH / Mo2CT x : Ni(NO3)2·6H2O, urea, C6H8O7·H2O, 1-ethyl-3-methylimidazolium tetrafluoroborate and Mo2CT x Add the mixture to deionized water, mix thoroughly, then heat the mixture, wash with ethanol and deionized water, and dry to obtain NBF-Ni-LDH / Mo2CT. x ; (2) Synthesis of NBF-NiSe2 / Mo2CT x : The NBF-Ni-LDH / Mo2CT x The product NBF-NiSe2 / Mo2CT was obtained by sintering with Se powder. x ; (3) Synthesis of Pt / NBF-NiSe2 / Mo2CT x : PtCl4 and NBF-NiSe2 / Mo2CT x The sample was placed in ethanol, stirred, and dried to obtain a sample. The sample was then sintered, washed with ethanol, and dried overnight to obtain the single-atom catalyst material Pt / NBF-NiSe2 / Mo2CT. x .
2. The method according to claim 1, characterized in that, The proportions of each raw material component in step (1) are as follows: Ni(NO3)2·6H2O 360 mg, urea 500 mg, C6H8O7·H2O 0.05 g, 1-ethyl-3-methylimidazolium tetrafluoroborate 1 mL, Mo2CT x 0.1g, 60mL of deionized water; the heating temperature of the mixed solution in step (1) is 150℃, the heating time is 12 hours, the drying temperature is 50-70℃, and the drying time is 12-24 hours.
3. The method according to claim 1, characterized in that, The proportions of each raw material component used in step (2) are as follows: NBF-Ni-LDH / Mo2CT x 100 mg of selenium powder and 400 mg of selenium powder were used in the sintering atmosphere of 95% Ar / 5% H2, with a heating rate of 10 °C / min. -1 The sintering temperature is 350℃ and the holding time is 1 hour.
4. The method according to claim 1, characterized in that, The proportions of each raw material component in step (3) are as follows: PtCl4 30mg, NBF-NiSe2 / Mo2CT x 50 mg, 30 mL ethanol; sintering atmosphere: 95% Ar / 5% H2, heating rate: 2 °C / min -1 The sintering temperature is 300℃ and the holding time is 1 hour.
5. The ionic liquid-assisted synthesis of MXene-derived single-atom catalysts prepared by the method according to any one of claims 1 to 4.
6. The application of the ionic liquid-assisted synthesis of MXene-derived single-atom catalysts according to claim 5 in the preparation of battery cathodes.
7. The application of the ionic liquid-assisted synthesis of MXene-derived single-atom catalysts according to claim 5 in the preparation of lithium-sulfur batteries.
8. A sulfur-carbon composite cathode comprising the ionic liquid-assisted synthesis of MXene-derived single-atom catalyst as described in claim 5.
9. The sulfur-carbon composite cathode according to claim 8, characterized in that, The sulfur-carbon composite cathode is a sulfur-carbon cathode, and the ionic liquid-assisted synthesis of MXene-derived single-atom catalyst is formed on the surface of the sulfur-carbon cathode as a modification layer.
10. A lithium sulfur battery, characterized in that, It includes the sulfur-carbon composite positive electrode, separator, lithium negative electrode, and electrolyte as described in claim 8 or 9.