CN113921817A - V-shaped groove3S4@V2C composite material and preparation method and application thereof - Google Patents
V-shaped groove3S4@V2C composite material and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a V3S4@V2C composite material and preparation method and application thereof, wherein the composite material comprises V with MXene structure2C and in situ generation at the V2V of C surface3S4. The V is3S4Having a three-dimensional NiAs crystal structure, said V2C is a two-dimensional material and V3S4Generated in situ at V2C make bothConstructing two-dimensional and three-dimensional heterogeneous crystal structures. V provided by the invention3S4@V2In C composite material, V3S4V with three-dimensional NiAs crystal structure and MXene structure2C is a two-dimensional material with a special structure, and three-dimensional V is converted in situ3S4And two-dimensional V2C build heterocrystal, V with good conductivity2C and V with catalytic sulfur-fixing effect3S4The mutual cooperation can effectively promote the diffusion and the conversion of polysulfide on the surface of an electrode, and the electrochemical performance of the lithium-sulfur battery is obviously improved.
Description
Technical Field
The invention relates to the technical field of preparation of lithium-sulfur battery materials, in particular to a needle V3S4@V2C composite material and its preparation method and application.
Background
The information in this background section is disclosed to enhance understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms part of the prior art already known to a person of ordinary skill in the art.
For the increasingly severe energy crisis and greenhouse effect, lithium ion batteries play an indispensable role in alleviating these problems. Has high energy density (2600 Wh-Kg) to meet the continuously developing market demand-1) The lithium sulfur battery of (a) is considered to be a next-generation ideal energy storage device expected to replace a lithium ion battery. However, unlike the lithium removal-insertion mechanism of the positive electrode of the commercial lithium ion battery, the lithium sulfur battery is accompanied by a complex multi-step solid-liquid phase reaction during the charging and discharging process, wherein the intermediate product of soluble lithium polysulfide can pass through the separator to the negative electrode, i.e. the so-called shuttle effect causes a series of problems such as loss of the positive active material, corrosion of the negative electrode metal lithium sheet, and the like, and seriously hinders the commercialization progress of the lithium sulfur battery.
To solve the shuttle effect from the source, attempts have been made to reduce the loss of the positive electrode sulfur by using various non-polar carbon materials as the sulfur-fixing matrix (such as porous carbon, carbon nanotube, graphene, etc.) in the past decades. However, it has been shown that shuttle effects can only be mitigated to some extent by reaction with polysulfides only by weak van der waals forces. Based on this, polar substrates that can strongly interact with polysulfides have been sought. Experiment proves that V3S4Is an ideal anode sulfur fixing material, not only for polysulfideHas strong anchoring effect and strong catalytic effect, and promotes the conversion of polysulfide to final products. However pure phase V3S4Large volume expansion (resulting in significant capacity fade) typically occurs during cycling. In addition, V of pure phase3S4Slow electron transport kinetics also further affect electrochemical performance, and therefore, people often modify nanostructures or composite conductive substrates by constructing the nanostructures.
In 2020, Seung-Deok Seo et al (Small, 2020.16.2004806) reported attachment of VO to one-step-formed layered porous carbon2/V3S4When the nano composite material is used as a positive electrode material of a lithium-sulfur battery, the shuttle effect can be effectively inhibited, and 665mAh g can be still maintained after 1000 cycles under the current density of 1C-1The capacity of (c). In 2020, Tianyu Tang et al (Science China Materials, 2020.63.1910) reported the attachment of V to graphene sheets prepared using a conventional high temperature vapor phase sulfidation process3S4Of a nanocomposite V3S4the-G also has excellent electrochemical performance when being used as a positive electrode material of a lithium-sulfur battery, but the preparation method of the precursor is too complicated and is not beneficial to subsequent large-scale production.
Disclosure of Invention
Aiming at the problems of complicated preparation method and V existing in the prior art3S4The invention provides a V which is easy to generate volume expansion and has slow electron transmission in the circulation process3S4@V2C composite material and its preparation method and application. The method can be used for preparing MXene material V simply and conveniently2In situ formation of V on C3S4@V2And C, when the obtained composite material is used as a positive electrode material of the lithium-sulfur battery, the diffusion and conversion of polysulfide on the surface of an electrode can be effectively promoted, and the excellent electrochemical performance is brought to the lithium-sulfur battery. In order to achieve the purpose, the invention discloses the following technical scheme:
in a first aspect of the invention, there is provided a V3S4@V2C composite material comprising V having MXene structure2C and in situ generation at the V2Granular V on C surface3S4。
Further, the V3S4Having a three-dimensional NiAs crystal structure, said V2C is a two-dimensional material and V3S4Generated in situ at V2And C, constructing the two into two-dimensional and three-dimensional heterogeneous crystal structures.
Further, the V3S4@V2The C composite material is of a sheet structure, and the thickness of the C composite material is in a nanometer level.
In a second aspect of the invention, there is provided a V3S4@V2The preparation method of the C composite material comprises the following steps: v with MXene structure2And C, placing the thioacetamide and the C in the same reaction environment for gas phase vulcanization treatment to obtain the thioacetamide.
Further, in the preparation method, V with MXene structure2The mass ratio of C to thioacetamide is controlled to be 1: 5-10, such as 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:10 and the like.
Further, the V with MXene structure2The preparation method of C comprises the following steps:
(1) providing an aqueous solution containing sodium fluoride and hydrochloric acid, adding V2And AlC, and uniformly mixing to obtain a precursor solution.
(2) Carrying out hydrothermal reaction on the precursor solution, separating a solid product in a reaction solution, cleaning and drying the solid product to obtain V with an MXene structure2C。
Further, in the step (1), the V2The mass ratio of AlC to sodium fluoride is preferably controlled to be 0.4-0.9: 1, such as 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.72:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1 and the like. The amount of water added may be sufficient to dissolve sodium fluoride, and the amount of hydrochloric acid added may be sufficient for V2The AlC is etched, and the invention is not particularly limited. Preferably, the aqueous solution uses deionized water as a solvent to reduce the effect of impurity ions in the water on the purity of the product.
Further, in the step (1), the concentration of the hydrochloric acid is not less than 8 mol/L. In the step, the main function of the hydrochloric acid is to form a mixed solution pair V with sodium fluoride2AlC is etched, and the use of high hydrochloric acid concentrations helps to produce high purity V2C MXene。
Further, in the step (1), sodium fluoride and hydrochloric acid are dissolved in water, and after standing for not less than 1 hour, the V is added2And then stirring for not less than 1 hour, and entering the next step. So as to fully release hydrogen generated in the etching process and reduce the danger in the subsequent high-temperature hydrothermal process.
Further, in the step (2), the temperature of the hydrothermal reaction is preferably maintained between 105 ℃ and 130 ℃, and the corresponding hydrothermal reaction time is preferably maintained between 40 hours and 55 hours. By hydrothermal reaction, HF generated in situ can be accelerated to V under the conditions of high temperature and high pressure2Reaction of AlC and V formation due to the hermetic environment2The purity of C is higher, and the influence of impurities on the electrochemical performance of the material is avoided.
Further, in the step (2), the drying temperature is 50-80 ℃, and the drying time is 10-24 hours. By drying
Further, in the step (2), the solid product is washed to be neutral, so that the residual acid liquor is prevented from causing adverse effects on subsequent reactions, instruments and the like.
Further, the method for the gas phase vulcanization treatment comprises the following steps: placing the thioacetamide upstream of a flowing shielding gas in an oxygen-isolated environment produced by the shielding gas, and placing the V2And C, placing the mixture at the downstream of the protective gas, and then carrying out heating and heat preservation treatment to obtain the coating.
Further, the heating and heat preservation temperature is 600-700 ℃, and the heat preservation time is 1-3 hours. During the gas phase sulfurizing treatment, thioacetamide produces reducing gas H at high temperature2S, mixing V2Reduction of C to V3S4. It should be noted that the holding temperature must not be too high, which would otherwise result in V2Complete conversion of C to V3S4。
Further, the shielding gas includes any one of an inert gas, nitrogen gas, or hydrogen-argon mixed gas, and the like.
In a third aspect of the present invention, there is provided the V3S4@V2The C composite material is applied to energy storage devices, such as a positive electrode material for a lithium sulfur battery and the like, and can effectively promote the diffusion and conversion of polysulfide on the surface of an electrode and improve the electrochemical performance of the lithium sulfur battery.
Compared with the prior art, the invention has the following beneficial and unique effects:
(1) v provided by the invention3S4@V2In C composite material, V in granular form3S4V with three-dimensional NiAs crystal structure and MXene structure2C is a two-dimensional material of special construction (i.e. V)2C MXene) and converting a portion of the V elements therein to V by in situ conversion3S4Meanwhile, the three-dimensional V is realized in the process3S4And two-dimensional V2C build heterocrystal, V with good conductivity2C and V with catalytic sulfur-fixing effect3S4The mutual cooperation can effectively promote the diffusion and the conversion of polysulfide on the surface of an electrode, and the electrochemical performance of the lithium-sulfur battery is obviously improved. This is because: v3S4@V2C composite inherits V2C has the characteristics of large specific surface area and many active sites, thereby increasing the contact area with the electrolyte and reducing the diffusion distance of lithium ions. At the same time V2V with different diameters are uniformly distributed on the C sheet layer3S4The nanoparticles, on the one hand, alleviate the pure phase V in the prior report3S4The problem of easy volume expansion during the circulation process; on the other hand V3S4The presence of which accelerates the conversion of long-chain lithium polysulphides to short-chain Li2S and Li2S2And V is3S4Having a ratio V to lithium polysulphides2C MXene has stronger chemical adsorption effect and can effectively inhibit shuttle effect, and V2The existence of C MXene as a conductive substrate effectively overcomes V3S4Slow electron transport. Both theory and experiment prove that, therefore, the flaky V disclosed by the invention3S4@V2The C composite material is a more ideal positive electrode material of the lithium-sulfur battery.
(2) Compared with the existing graphene sheet, the graphene sheet is adhered with V3S4Of (D) a composite material (V)3S4-G) preparation method, the nano-sheet V provided by the invention3S4@V2The preparation method of the C composite material has fewer raw material types and simpler steps, so that the obtained product has high purity and is more suitable for large-scale production.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:
FIG. 1 shows a precursor V prepared according to a first embodiment of the present invention2SEM picture of C.
FIG. 2 shows a precursor V prepared according to a first embodiment of the present invention2XRD pattern of C.
FIG. 3 is a V prepared according to a first embodiment of the present invention3S4@V2SEM pictures (a) and FESEM pictures (b) of the C nanocomposite material.
FIG. 4 is a graph of V prepared in accordance with a first embodiment of the present invention3S4@V2TEM pictures (a picture) and HRTEM pictures (b, C picture) of the C composite.
FIG. 5 is a graph of V prepared in accordance with a first embodiment of the present invention3S4@V2XRD pattern of the C composite material.
FIG. 6 is a graph of V prepared in accordance with a first embodiment of the present invention3S4@V2Cycling data for the C composite as a lithium sulfur battery positive electrode material (current density of 0.2C).
FIG. 7 is a V prepared by a sixth embodiment of the present invention3S4XRD pattern of (a).
FIG. 8 is a V prepared according to a sixth embodiment of the present invention3S4Cycling data plot as a positive electrode material (current density of 0.2C) for a lithium sulfur battery.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The reagents or starting materials used in the present invention can be purchased from conventional sources, and unless otherwise specified, the reagents or starting materials used in the present invention can be used in a conventional manner in the art or in accordance with the product specifications. In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention. The preferred methods and materials described in this invention are exemplary only. The invention will now be further described with reference to the drawings and specific examples in the specification.
First embodiment
V-shaped groove3S4@V2The preparation method of the C composite material comprises the following steps:
(1) taking 20 mL of deionized water into a 50 mL reaction kettle lining, adding 20 mL of concentrated hydrochloric acid (the concentration is 12 mol/L) and 1.0g of sodium fluoride into the lining, stirring by using a magnetic stirrer until the sodium fluoride is completely dissolved in the deionized water, and then adding 0.72g of MAX phase material V2And continuing to stir AlC for 1 hour to obtain a precursor solution for later use.
(2) Putting the liner filled with the precursor solution into a reaction kettle, heating to 120 ℃, preserving heat for 48 hours, naturally cooling, centrifugally washing the obtained reaction liquid with deionized water until the pH is =7, putting the obtained solid product into a dryer, and drying at 60 ℃ for 12 hours to obtain a black powdery precursor (namely V with an MXene structure)2C) And then standby.
(3) Taking 0.1 g of the precursor, placing the precursor in a porcelain boat (marked as porcelain boat 1), then taking 0.5 g of thioacetamide, placing the thioacetamide in the porcelain boat (marked as porcelain boat 2), placing the porcelain boat 2 in the upstream of the flow of the protective gas in the tube furnace, and placing the porcelain boat 1 in the downstream of the flow of the protective gas in the tube furnace, wherein the protective gas is flowing nitrogen. After the completion, the temperature is raised to 700 ℃ at the speed of 3 ℃/min and kept for 3 hours. Naturally cooling after the heat preservation is finished to obtain a target product V3S4@V2C。
Second embodiment
V-shaped groove3S4@V2The preparation method of the C composite material comprises the following steps:
(1) taking 20 mL of deionized water into a 50 mL reaction kettle lining, adding 20 mL of concentrated hydrochloric acid (the concentration is 12 mol/L) and 1.0g of sodium fluoride into the lining, stirring by using a magnetic stirrer until the sodium fluoride is completely dissolved in the deionized water, and then adding 0.72g of MAX phase material V2And continuing to stir AlC for 1 hour to obtain a precursor solution for later use.
(2) Putting the liner filled with the precursor solution into a reaction kettle, heating to 120 ℃, preserving heat for 48 hours, naturally cooling, centrifugally washing the obtained reaction liquid with deionized water until the pH is =7, putting the obtained solid product into a dryer, and drying at 80 ℃ for 10 hours to obtain a black powdery precursor (namely V with an MXene structure)2C) And then standby.
(3) Taking 0.1 g of the precursor, placing the precursor in a porcelain boat (marked as porcelain boat 1), then taking 1 g of thioacetamide, placing the thioacetamide in the porcelain boat (marked as porcelain boat 2), placing the porcelain boat 2 in the upstream of the flow of the protective gas in the tube furnace, and placing the porcelain boat 1 in the downstream of the flow of the protective gas in the tube furnace, wherein the protective gas is flowing nitrogen. After completion, the temperature is raised to 600 ℃ at the rate of 1 ℃/min and kept for 3 hours. Naturally cooling after the heat preservation is finished to obtain a target product V3S4@V2C。
Third embodiment
V-shaped groove3S4@V2C complexThe preparation method of the composite material comprises the following steps:
(1) taking 20 mL of deionized water into a 50 mL reaction kettle lining, adding 20 mL of concentrated hydrochloric acid (the concentration is 12 mol/L) and 1.0g of sodium fluoride into the lining, stirring by using a magnetic stirrer until the sodium fluoride is completely dissolved in the deionized water, and then adding 0.72g of MAX phase material V2And continuing to stir AlC for 1 hour to obtain a precursor solution for later use.
(2) Putting the liner filled with the precursor solution into a reaction kettle, heating to 120 ℃, preserving heat for 48 hours, naturally cooling, centrifugally washing the obtained reaction liquid with deionized water until the pH is =7, putting the obtained solid product into a dryer, and drying at 60 ℃ for 24 hours to obtain a black powdery precursor (namely V with MXene structure)2C) And then standby.
(3) Taking 0.1 g of the precursor, placing the precursor in a porcelain boat (marked as porcelain boat 1), then taking 0.5 g of thioacetamide, placing the thioacetamide in the porcelain boat (marked as porcelain boat 2), placing the porcelain boat 2 in the upstream of the flow of the protective gas in the tube furnace, and placing the porcelain boat 1 in the downstream of the flow of the protective gas in the tube furnace, wherein the protective gas is flowing nitrogen. After completion, the temperature is raised to 700 ℃ at the rate of 1 ℃/min and kept for 1 hour. Naturally cooling after the heat preservation is finished to obtain a target product V3S4@V2C。
Fourth embodiment
V-shaped groove3S4@V2The preparation method of the C composite material comprises the following steps:
(1) taking 20 mL of deionized water into a 50 mL reaction kettle lining, adding 30 mL of concentrated hydrochloric acid (the concentration is 8 mol/L) and 1.0g of sodium fluoride into the lining, stirring by using a magnetic stirrer until the sodium fluoride is completely dissolved in the deionized water, standing for 1 hour, and adding 0.9g of MAX phase material V2And continuing to stir AlC for 1 hour to obtain a precursor solution for later use.
(2) Putting the liner filled with the precursor solution into a reaction kettle, heating to 105 ℃, preserving heat for 55 hours, naturally cooling, centrifugally washing the obtained reaction liquid with deionized water until the pH value is =7, and placing the obtained solid product in the reaction kettleDrying in a drier at 50 deg.C for 24 hr to obtain black powder precursor (V with MXene structure)2C) And then standby.
(3) Taking 0.1 g of the precursor, placing the precursor in a porcelain boat (marked as porcelain boat 1), then taking 0.8 g of thioacetamide, placing the thioacetamide in the porcelain boat (marked as porcelain boat 2), placing the porcelain boat 2 in the upstream of the flow of the protective gas in the tube furnace, and placing the porcelain boat 1 in the downstream of the flow of the protective gas in the tube furnace, wherein the protective gas is flowing nitrogen. After completion, the temperature is raised to 600 ℃ at the rate of 3 ℃/min and kept for 3 hours. Naturally cooling after the heat preservation is finished to obtain a target product V3S4@V2C。
Fifth embodiment
V-shaped groove3S4@V2The preparation method of the C composite material comprises the following steps:
(1) taking 20 mL of deionized water into a 50 mL reaction kettle lining, adding 25mL of concentrated hydrochloric acid (the concentration is 10 mol/L) and 1.0g of sodium fluoride into the lining, stirring by using a magnetic stirrer until the sodium fluoride is completely dissolved in the deionized water, standing for 1 hour, and adding 0.4g of MAX phase material V2And continuing to stir AlC for 1 hour to obtain a precursor solution for later use.
(2) Putting the liner filled with the precursor solution into a reaction kettle, heating to 130 ℃, preserving heat for 40 hours, naturally cooling, centrifugally washing the obtained reaction liquid with deionized water until the pH is =7, putting the obtained solid product into a dryer, and drying at 60 ℃ for 20 hours to obtain a black powdery precursor (namely V with an MXene structure)2C) And then standby.
(3) Taking 0.1 g of the precursor, placing the precursor in a porcelain boat (marked as porcelain boat 1), then taking 1 g of thioacetamide, placing the thioacetamide in the porcelain boat (marked as porcelain boat 2), placing the porcelain boat 2 in the upstream of the flow of the protective gas in the tube furnace, and placing the porcelain boat 1 in the downstream of the flow of the protective gas in the tube furnace, wherein the protective gas is flowing nitrogen. After completion, the temperature was raised to 650 ℃ at a rate of 3 ℃/min and held for 2 hours. Naturally cooling after the heat preservation is finished to obtain a target product V3S4@V2C。
Sixth embodiment
V-shaped groove3S4@V2The preparation method of the C composite material comprises the following steps:
(1) taking 20 mL of deionized water into a 50 mL reaction kettle lining, adding 20 mL of concentrated hydrochloric acid (the concentration is 12 mol/L) and 1.0g of sodium fluoride into the lining, stirring by using a magnetic stirrer until the sodium fluoride is completely dissolved in the deionized water, and then adding 0.72g of MAX phase material V2And continuing to stir AlC for 1 hour to obtain a precursor solution for later use.
(2) Putting the liner filled with the precursor solution into a reaction kettle, heating to 120 ℃, preserving heat for 48 hours, naturally cooling, centrifugally washing the obtained reaction liquid with deionized water until the pH is =7, putting the obtained solid product into a dryer, and drying at 60 ℃ for 24 hours to obtain a black powdery precursor (namely V with MXene structure)2C) And then standby.
(3) Taking 0.1 g of the precursor, placing the precursor in a porcelain boat (marked as porcelain boat 1), then taking 0.5 g of thioacetamide, placing the thioacetamide in the porcelain boat (marked as porcelain boat 2), placing the porcelain boat 2 in the upstream of the flow of the protective gas in the tube furnace, and placing the porcelain boat 1 in the downstream of the flow of the protective gas in the tube furnace, wherein the protective gas is flowing nitrogen. After the completion, the temperature is raised to 800 ℃ at the speed of 3 ℃/min and kept for 1 hour. Naturally cooling after the heat preservation is finished to obtain a target product (V)3S4）。
Performance testing
FIG. 1 shows a few layers V prepared in step (2) of the first embodiment2SEM image of material C, it can be seen that this material has a two-dimensional lamellar structure characteristic of MXene material.
FIG. 2 shows a few layers V prepared in step (2) of the first embodiment2XRD pattern of material C, which demonstrates the successful synthesis of composition V in the first example2MXene material of C.
FIG. 3 is an SEM image (a) and an FESEM image (b) of the target product prepared in the step (3) of the first embodiment, wherein the target product inherits from the aV is2MXene two-dimensional lamellar structure of C material, and particles with different sizes are attached to the surface (figure b).
Fig. 4 is a TEM image (a view) and an HRTEM (b, c view) of the target product prepared in the step (3) of the first embodiment, wherein c is an enlarged view of a circled portion in b view. It can be seen that the composition of the target product is at V2V is adhered to the surface of the C-layer sheet3S4And (3) granules.
FIG. 5 is an XRD image of the target product prepared in step (3) of the first example, demonstrating the successful synthesis of V in the first example3S4@V2And C, a heterostructure.
FIG. 6 is a graph showing the discharge curve at 0.2C current and the coulombic efficiency of the objective product prepared in step (3) of the first example (electrolyte is 1M lithium bis (trifluoromethane) sulfonamide (LiTFSI) dissolved in a mixed solvent of DOL and DME at a volume ratio of 1:1, and contains 1.0% LiNO)3(ii) a The voltage interval is 1.7-2.8V; the surface loading amount is 1.17 mg cm-2). It can be seen that: target product V3S4@V2The discharge specific capacity of the C composite material as the first ring of the lithium-sulfur battery anode material is up to 1127.7mAh g-1And the capacity of 82% can be still maintained after 300 cycles of the cycle, and excellent electrochemical performance is shown.
FIG. 7 is an XRD pattern of the objective product obtained in step (3) of the sixth example, which shows that V2C can be completely converted into V at the high temperature of 800 DEG C3S4。
FIG. 8 shows the target product (V) obtained in step (3) of the sixth example3S4) Discharge curve and coulombic efficiency at 0.2C current density (electrolyte is dissolved in a volume ratio of 1:1 of lithium bis (trifluoromethane) sulfonamide (LiTFSI) in a mixed solvent of DOL and DME, and containing 1.0% LiNO3(ii) a The voltage interval is 1.7-2.8V; the surface loading amount is 1.13 mg cm-2). It can be seen that the sheet V prepared in comparison with the first example3S4@V2Composite of C heterostructure, pure V3S4As the anode material of lithium-sulfur batteryThe discharge capacity of the first ring is only 806.5mAh g-1And the capacity remained only the previous 74% after 300 cycles, causing this result due to the flaky V3S4@V2C heterostructure with improved phase-pure V3S4The problems of volume expansion, slow electron transmission and the like in the circulation process can better inhibit the shuttle effect of the lithium-sulfur battery, thereby bringing higher specific capacity and circulation stability.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. V-shaped groove3S4@V2C composite material comprising V having MXene structure2C and in situ generation at the V2Granular V on C surface3S4。
2. V according to claim 13S4@V2C composite material, characterized in that said V3S4Having a three-dimensional NiAs crystal structure, said V2C is a two-dimensional material and V3S4Generated in situ at V2And C, constructing the two into two-dimensional and three-dimensional heterogeneous crystal structures.
3. V according to claim 1 or 23S4@V2C composite material, characterized in that said V3S4@V2The C composite material is of a sheet structure, and the thickness of the C composite material is in a nanometer level.
4. V-shaped groove3S4@V2Method for producing C composite material, and the sameCharacterized in that it comprises:
v with MXene structure2And C, carrying out gas-phase vulcanization treatment on the thioacetamide and the C in the same reaction environment to obtain the thioacetamide.
5. V according to claim 43S4@V2The preparation method of the C composite material is characterized in that the V with the MXene structure2The mass ratio of C to thioacetamide is 1: 5-10.
6. V according to claim 43S4@V2The preparation method of the C composite material is characterized in that the gas phase vulcanization treatment method comprises the following steps: placing the thioacetamide upstream of a flowing shielding gas in an oxygen-isolated environment produced by the shielding gas, and placing the V2C, placing the mixture at the downstream of the protective gas, and then carrying out heating and heat preservation treatment to obtain the coating;
preferably, the heating and heat preservation temperature is 600-700 ℃, and the heat preservation time is 1-3 hours;
preferably, the shielding gas comprises any one of an inert gas, nitrogen gas or hydrogen-argon mixed gas.
7. V according to any one of claims 4 to 63S4@V2The preparation method of the C composite material is characterized in that the V with the MXene structure2The preparation method of C comprises the following steps:
(1) providing an aqueous solution containing sodium fluoride and hydrochloric acid, adding V2AlC, uniformly mixing to obtain a precursor solution;
(2) carrying out hydrothermal reaction on the precursor solution, separating a solid product in a reaction solution, cleaning and drying the solid product to obtain V with an MXene structure2C。
8. V according to claim 73S4@V2The preparation method of the C composite material is characterized in that in the step (1), the V is2The mass ratio of AlC to sodium fluoride is 0.4-0.9: 1；
Preferably, in step (1), the aqueous solution uses deionized water as a solvent;
preferably, in the step (1), the hydrochloric acid concentration is not less than 5 mol/L;
preferably, in the step (1), the sodium fluoride and the hydrochloric acid are dissolved in the water, and the V is added after the solution is stood for not less than 1 hour2And then stirring for not less than 1 hour, and entering the next step.
9. V according to claim 73S4@V2The preparation method of the C composite material is characterized in that in the step (2), the temperature of the hydrothermal reaction is 105-130 ℃, and the reaction time is 40-55 hours;
preferably, in the step (2), the drying temperature is 50-80 ℃, and the drying time is 10-24 hours;
preferably, in step (2), the solid product is washed to neutrality.
10. V according to any one of claims 1 to 33S4@V2C composite or V prepared by the method of any one of claims 4 to 93S4@V2The use of C composite materials in energy storage devices, preferably V3S4@V2The C composite material is used as a positive electrode material of the lithium-sulfur battery.
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