Bimetallic vti04 / vticT x Method for manufacturing schottky heterostructure

Abstract

The application belongs to the technical field of lithium ion storage materials, and particularly relates to a bimetallic VTiO4 / VTiCT x The application relates to a preparation method of a Schottky heterostructure, 1, LiF is added into a concentrated HCl solution, a reaction agent is obtained after stirring, micron-level VTiAlC particles are added into the reaction agent to prepare a precursor VTiCT x ; 2, the reaction agent is cleaned, ultrasonic treatment is carried out, and VTiCT in the upper layer of the reaction agent is collected by low-speed centrifugation x ; 3, the VTiCT x suspension liquid is concentrated, a precipitate is obtained in a reaction kettle, the precipitate is vacuum-filtered, cleaned and dried, the dried product is ground into powder, annealing treatment is carried out, and hydrogen and argon are passed through, so that the bimetallic VTiO4 / VTiCT x Schottky heterostructure is prepared. As a lithium ion storage electrode material, the Schottky heterostructure has the advantages of high mass specific capacitance, excellent rate performance and long cycle life.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion storage materials, and particularly relates to a bimetallic VTiO4 / VTiCT x Preparation method of Schottky heterostructure. BACKGROUND

[0002] With the development of industrial society, people's requirements and dependence on energy storage devices have gradually increased. Lithium ion storage devices have attracted widespread attention due to their high capacity, wide working temperature range and excellent safety. At present, lithium ion storage devices appear in various fields and are closely related to human social activities, and their use has spread all over the world. It has become an inevitable trend to develop lithium ion storage devices with high energy density, fast charging speed and good cycle stability. In the component of lithium ion storage devices, electrode materials are the core, therefore, developing new electrode materials with excellent performance is the key to building high-performance energy storage systems. New two-dimensional (2D) graphene-like electrode materials, MXenes, with unique physical and chemical properties, are worth paying attention to in lithium ion storage devices, which have excellent lithium ion storage capacity and cycle stability.

[0003] MXenes are generally obtained by removing the A atom layer in the MAX phase. Due to its unique layered structure, excellent electronic conductivity and adjustable surface / interface structure, it has been widely studied in many fields including lithium ion storage devices. The theoretical lithium ion storage capacity of MXenes is about ~ 500 mAh g -1 , which is better than graphite, however, its actual lithium ion storage capacity tends to be moderate, about ~ 300 mAh g -1 . Increasing the active surface area of MXenes electrode materials is an important means to improve its electrochemical performance, which can increase the contact area and diffusion speed of electrolyte and MXenes, and belongs to the macroscopic optimization of MXenes. Optimizing the intrinsic properties of MXenes such as conductivity, lithium affinity, etc. by constructing heterostructures to improve the electrochemical performance of the material is a kind of micro-control of the atomic structure of MXenes. Therefore, the combination of macroscopic optimization and micro-control strategy can comprehensively improve the performance of MXenes. SUMMARY

[0004] Based on the above technical background, the application prepares a heterostructure of bimetallic VTiCT x MXene, namely bimetallic VTiO4 / VTiCT x Schottky heterostructure. The preparation method of the bimetallic VTiO4 / VTiCT x Schottky heterostructure is simple, low in cost, economical and environmentally friendly, and has strong reproducibility. And has broad application prospect.

[0005] The technical scheme adopted by the present application is as follows: a bimetallic VTiO4 / VTiCT x A preparation method of a Schottky heterostructure, the preparation method comprising the following steps:

[0006] Step one, preparation of precursor VTiCT x

[0007] LiF is added into a concentrated HCl solution, and after stirring, a reaction agent is obtained; micron-sized VTiAlC particles are added into the reaction agent, and after stirring and dissolving, the solution is transferred into a polytetrafluoroethylene hydrothermal reaction kettle; the solution is stirred at a temperature of 30 o C 55 o C for 20 h to 60 h to obtain a reaction product (precursor VTiCT x );

[0008] Step two, preparation of VTiCT x nanosheet suspension

[0009] The reaction product obtained in step one is washed, and a dilute HCl solution, an ethanol solution and deionized water are used in sequence for high-speed centrifugal washing for several times; the precipitate after washing is subjected to ultrasonic treatment, and a low-speed centrifugal method is used to collect the upper suspension, which is a VTiCT x nanosheet suspension;

[0010] Step three, preparation of a bimetallic VTiO4 / VTiCT x Schottky heterostructure

[0011] The VTiCT x suspension is concentrated by high-speed centrifugation; the concentrated VTiCT x suspension is transferred into a polytetrafluoroethylene hydrothermal reaction kettle; the solution is kept at a temperature of 150 o C to 250 o C for 0.5 h to 2.5 h to obtain a precipitate; the precipitate is vacuum filtered and washed; the product after filtration and washing is vacuum dried for 10 h to 30 h; the dried product is ground into powder and subjected to annealing treatment in a furnace for 0.5 h to 2.5 h, and hydrogen gas and argon gas are passed through at a ratio of 1:9 to obtain a bimetallic VTiO4 / VTiCT x Schottky heterostructure.

[0012] Further, in step one, 2.5 g of LiF is added into 25 mL of an HCl aqueous solution to obtain a reaction agent, the concentration of the HCl aqueous solution is 37%, and then 0.5 g to 1.2 g of VTiAlC particles are added into the reaction agent to obtain a reaction product, the size of the VTiAlC particles is less than 15 μm.​

[0013] Further, the rotation speed of the polytetrafluoroethylene hydrothermal reactor in step one is 300 rpm.

[0014] Further, the concentration of the dilute HCl aqueous solution in step two is 3.7%, and the dilute HCl aqueous solution is 150 mL.

[0015] Further, the dilute HCl aqueous solution, the ethanol solution and the deionized water in step two are respectively washed by high-speed centrifugation for 3-5 times.

[0016] Further, the high-speed centrifugation in step two is centrifugation at a rotation speed greater than 9000 rpm for 3-5 min; and the low-speed centrifugation is centrifugation at a rotation speed of 3000-4000 rpm for 3-5 min.

[0017] Further, the VTiCT x in step three is prepared by the method of the present application. -1 .

[0018] Further, the temperature for vacuum drying the reactants in step three is 75 o C.

[0019] Further, the powder in step three is annealed at 430 o C-470 o C.

[0020] Further, the prepared bimetallic VTiO4 / VTiCT x Schottky heterostructure is used as a lithium ion storage electrode material.

[0021] The present application has the beneficial effect of providing a preparation method of a bimetallic VTiO4 / VTiCT x Schottky heterostructure and its application. The preparation method of the bimetallic VTiO4 / VTiCT x Schottky heterostructure is simple, low in cost, economic and environmentally friendly, and has strong reproducibility. Moreover, the application prospect is wide, and the bimetallic VTiO4 / VTiCT x Schottky heterostructure material has excellent lithium ion storage mass specific capacitance and cycle stability. When the current density is 0.05 A g -1 , the mass specific capacitance can reach 450 mAh g -1 , and the mass specific capacity is more than 400 mAh g -1 under a small current density of 0.1 A g -1 in a 300-cycle process, and no capacity decay is observed. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a bimetallic VTiO4 / VTiCT x Schottky heterostructure, VTiO4 and VTiCT x X-ray diffraction spectrum; wherein 1 represents sharp VTiO4 / VTiCT x , 2 represents VTiO4, and 3 represents VTiCT x ;

[0023] Figure 2 is a bimetallic VTiO4 / VTiCT x Schottky heterostructure;

[0024] Figure 3 is a bimetallic VTiO4 / VTiCT x Schottky heterostructure under different current densities;

[0025] Figure 4 is a bimetallic VTiO4 / VTiCT x Schottky heterostructure under a current density of 0.1 A g -1 -1. Embodiment

[0026] Example

[0027] A preparation method of a bimetallic VTiO4 / VTiCT x Schottky heterostructure, the preparation method comprising the following steps:

[0028] Step one, preparation of precursor VTiCT x nanosheet

[0029] 2.5 g of LiF was added to 25 mL of an aqueous HCl solution to prepare a reaction agent, the concentration of the aqueous HCl solution being 37%, and then 0.5 g of VTiAlC particles with a size less than 15 μm were added to the reaction agent; after stirring and dissolving, the solution was transferred to a polytetrafluoroethylene hydrothermal reactor, the rotation speed of the reactor being 300 rpm, and the solution was stirred at a temperature of 30 o C for 20 h to obtain a reaction product (precursor VTiCT x nanosheet);

[0030] Step two, preparation of precursor VTiCT x nanosheet suspension

[0031] The reactant obtained in step one is washed with dilute HCl solution, ethanol solution and deionized water in turn, and high-speed centrifugal washing is performed for 3 times, wherein the concentration of the dilute HCl aqueous solution is 3.7%, the dilute HCl aqueous solution is 150 mL, and the high-speed centrifugal washing is performed at a speed greater than 9000 rpm for 3 min; the precipitate after washing is subjected to ultrasonic treatment, and the upper suspension liquid is collected by low-speed centrifugation, wherein the low-speed centrifugation is performed at a speed of 3000 rpm for 3 min, and the suspension liquid is VTiCT x nanosheet suspension liquid;

[0032] Step three, bimetallic VTiO4 / VTiCT x Preparation of a Schottky heterostructure

[0033] VTiCT x The suspension liquid is concentrated by centrifugation at a speed of 10000 rpm for 30 min (high-speed centrifugation), and the VTiCT x The concentration of the suspension liquid is 5 mg mL -1 After the concentrated VTiCT x The suspension liquid is transferred to a polytetrafluoroethylene hydrothermal reactor, and the temperature is kept at 150 o C for 0.5 h to obtain a precipitate, the precipitate is vacuum filtered and washed, the product after filtration and washing is vacuum dried for 10 h, the temperature of vacuum drying is 75 o C, the dried product is ground into powder, and the powder is annealed in a furnace at 430 o C for 0.5 h, and hydrogen gas and argon gas are passed through the powder at a ratio of 1:9 to obtain bimetallic VTiO4 / VTiCT x Schottky heterostructure.

[0034] Embodiment

[0035] A bimetallic VTiO4 / VTiCT x Schottky heterostructure, and the preparation method comprises the following steps:

[0036] Step one, preparation of precursor VTiCT x

[0037] 2.5 g of LiF is added to 25 mL of HCl aqueous solution to obtain a reactant, the concentration of the HCl aqueous solution is 37%, and then 1.2 g of VTiAlC particles with a size less than 15 μm is added to the reactant; after stirring and dissolving, the solution is transferred to a polytetrafluoroethylene hydrothermal reactor, the speed of the reactor is 300 rpm, and the temperature is kept at 55 o C for 60 h to obtain a reactant (precursor VTiCT x ).​

[0038] Step two, precursor VTiCT x Preparation of nanosheet suspension

[0039] The reactant obtained in step one is washed with dilute HCl solution, ethanol solution and deionized water in sequence by high-speed centrifugal washing for 5 times, wherein the concentration of the dilute HCl aqueous solution is 3.7%, the dilute HCl aqueous solution is 150 mL, and the high-speed centrifugal washing is centrifuged at a speed greater than 10000 rpm for 5 min; the precipitate after washing is ultrasonically treated, and the upper suspension is collected by low-speed centrifugation, wherein the low-speed centrifugation is centrifuged at a speed of 4000 rpm for 5 min, and the suspension is VTiCT x Nanosheet suspension

[0040] Step three, bimetallic VTiO4 / VTiCT x Preparation of Schottky heterostructure

[0041] VTiCT x The suspension is concentrated by centrifugation at a speed of 10000 rpm for 30 min (high-speed centrifugation), and the VTiCT x The concentration of the suspension is 6 mg mL -1 After the concentrated VTiCT x The suspension is transferred to a polytetrafluoroethylene hydrothermal reactor, and the temperature is kept at 250 o C for 2.5 h to obtain a precipitate, which is vacuum filtered and washed, and the product after filtration and washing is vacuum dried for 130 h at a temperature of 75 o C, and the dried product is ground into powder and placed in a furnace for annealing treatment of the powder at 470 o C for 2.5 h under hydrogen and argon in a ratio of 1:9 to obtain the bimetallic VTiO4 / VTiCT x Schottky heterostructure

[0042] Embodiment

[0043] A bimetallic VTiO4 / VTiCT x Schottky heterostructure

[0044] Step one, preparation of precursor VTiCT x

[0045] ​A reaction agent was prepared by adding 2.5 g of LiF into 25 mL of an aqueous HCl solution with a concentration of 37%, and then adding 0.9 g of VTiAlC particles with a size of less than 15 μm into the reaction agent; after stirring and dissolving, the solution was transferred into a polytetrafluoroethylene hydrothermal reaction kettle, the rotation speed of the reaction kettle was 300 rpm, and a reaction product (precursor VTiCT x ) was obtained after stirring and reacting at a temperature of 43 C for 40 h.

[0046] Step two, precursor VTiCT x Preparation of a nanosheet suspension

[0047] The reaction product obtained in step one was washed, and high-speed centrifugal washing was performed four times using a dilute HCl solution, an ethanol solution, and deionized water in sequence, wherein the concentration of the dilute HCl aqueous solution was 3.7%, the dilute HCl aqueous solution was 150 mL, and the high-speed centrifugal washing was performed at a rotation speed of greater than 9000 rpm for 4 min; the precipitate after washing was subjected to ultrasonic treatment, and the upper suspension was collected using low-speed centrifugal washing, the low-speed centrifugal washing was performed at a rotation speed of 3500 rpm for 4 min, and the suspension was a VTiCT x nanosheet suspension.

[0048] Step three, bimetallic VTiO4 / VTiCT x Preparation of a Schottky heterostructure

[0049] The VTiCT x suspension was concentrated by centrifugation at a rotation speed of 10000 rpm for 30 min (high-speed centrifugation), the concentration of the VTiCT x suspension was 5.5 mg mL -1 After the concentrated VTiCT x suspension was transferred into a polytetrafluoroethylene hydrothermal reaction kettle, the precipitate was obtained after the temperature was maintained at 200 o C for 1 h or 1.5 h, the precipitate was vacuum filtered and washed, the product after filtration and washing was vacuum dried for 20 h or 24 h at a temperature of 75 o C, the dried product was ground into powder, and the powder was placed in a furnace for annealing treatment at 450 o C for 1 h or 1.5 h in a hydrogen atmosphere and an argon atmosphere with a ratio of 1:9, and a bimetallic VTiO4 / VTiCT x Schottky heterostructure was prepared.

[0050] Embodiment

[0051] In the preparation method of the anatase phase VTiO4

[0052] In step one, the polytetrafluoroethylene hydrothermal reactor is sealed and stirred in a water bath, the reaction temperature is 45 o C or 50 o C, and the reaction time is 45 h or 50 h.

[0053] Example

[0054] The bimetallic VTiO4 / VTiCT x Schottky heterostructure is used as a lithium ion storage electrode material.

[0055] Based on the above examples, Figure 1 The prepared anatase phase VTiO4 transmission electron microscope image can be seen from the figure that VTiO4 is granular morphology. Figure 2 The X-ray diffraction spectrum of anatase phase VTiO4 can be seen from the figure, and the X-ray diffraction spectrum of the synthesized product is consistent with that of anatase TiO2, indicating that the anatase phase VTiO4 is successfully prepared. Figure 1

[0056] Figure 2 The bimetallic VTiO4 / VTiCT x Schottky heterostructure X-ray diffraction spectrum can be seen from the figure, and the synthesized product contains VTiO4 and VTiCT x X-ray diffraction peaks, and there is no other diffraction peak, indicating that the bimetallic VTiO4 / VTiCT x Schottky heterostructure is successfully prepared.

[0057] Figure 3 The bimetallic VTiO4 / VTiCT x Schottky heterostructure transmission electron microscope image can be seen from the figure, and the VTiO4 particles grow on the VTiCT x Nanosheet, forming a heterostructure.

[0058] The bimetallic VTiO4 / VTiCT x Schottky heterostructure is used as a lithium ion storage electrode material, and the electrochemical test is as follows:

[0059] Assembly of lithium ion battery:

[0060] The working electrode is first mixed with the bimetallic VTiO4 / VTiCT x Schottky heterostructure, conductive PVDF and conductive agent acetylene black in a mass ratio of 8: 1: 1 to form a slurry, and the slurry is uniformly coated on a copper foil to form. Select polypropylene film as a separator, 1 mol L -1 ​LiPF6 was used as the electrolyte (the volume ratio of ethylene carbonate and diethyl carbonate was 1:1), the coated electrode was used as the working electrode, and the metal lithium sheet was used as the counter electrode to assemble into a button cell.

[0061] Electrochemical performance test:

[0062] The charge-discharge performance and cycle performance of the working electrode at different current densities were tested using a LAND CT2001A blue-electric battery testing system. The test voltage range of the assembled device was 0.01–3 V.

[0063] Bimetallic VTiO4 / VTiCT prepared in Example 3 x The mass specific capacitance of the Schottky heterostructure working electrode at different current densities is shown in Figure 2. Figure 3 .from Figure 4 It can be seen that at 0.05 A g -1 At a current density of VTiO4 / VTiCT x The mass specific capacitance of the working electrode is as high as 450 mAh g -1 , and at 5.00 A g -1 Even at a high current density of 160 mAh g -1 The mass specific capacitance of VTiO4 / VTiCT shows its excellent rate performance. x The long cycle performance of the working electrode is shown in Figure 4 ,from ​ It can be seen that at 0.1 A g -1 At a current density of 1.5 GHz, the mass specific capacitance did not decay during 300 cycles, indicating that it has excellent cycle stability.

[0064] The bimetallic VTiO4 / VTiCT in the above embodiment x The preparation method of Schottky heterostructure solves the problem of low actual lithium ion storage capacity of MXenes and develops a bimetallic VTiO4 / VTiCT x Schottky heterostructure preparation method. The prepared bimetallic VTiO4 / VTiCT x As a lithium-ion storage electrode material, Schottky heterostructure has the characteristics of high mass-to-capacitance, excellent rate performance and long cycle life.

Claims

1. A bimetallic VTi04 / VTiCT x A method for producing a Schottky heterostructure, characterized in that: The preparation method comprises the following steps: Step one, preparation of precursor VTiCT x Step two, preparation of VTiCT In the concentrated HCl solution, LiF is added, stirred to obtain a reaction agent, micron-sized VTiAlC particles are added to the reaction agent, stirred and dissolved, and then the solution is transferred to a polytetrafluoroethylene hydrothermal reaction kettle, and stirred at 30 o C~55 o C~55 o C~55 o C~55 o C~55 o C~55 o C~55 o C~55 o C~55 o C~55 o C~55 o C~55 o C~55 o C~55 o C~55 o Step two, precursor VTiCT x Preparation of nanosheet suspensions The reaction product obtained in step one is washed with dilute HC1 solution, ethanol solution and deionized water in turn by high speed centrifugal washing for several times. The precipitate after washing is ultrasonically treated, and the upper suspension is collected by low speed centrifugation. The suspension is VTiCT x nanosheet suspension; Step three, bimetallic VTiO4 / VTiCT x Fabrication of Schottky heterostructures VTiCT x The suspension was concentrated by high speed centrifugation. The concentrated VTiCT x The suspension was transferred into a Teflon autoclave and kept at 150 o C~250 o After keeping at the temperature of C~250 for 0.5 h~2.5 h, the precipitate was obtained. The precipitate was vacuum filtered and washed. The product after filtration and washing was vacuum dried for 10 h~30 h. The dried product was ground into powder and annealed in a furnace for 0.5 h~2.5 h with hydrogen and argon gas at a ratio of 1:9 to obtain the bimetallic VTiO4 / VTiCT x Schottky heterostructure.

2. The bimetallic VTi04 / VTiCT of claim 1 x The method for manufacturing a Schottky heterostructure is characterized in that: In the step one, 2.5 g of LiF is added into 25 mL of HCl aqueous solution to prepare a reaction agent, the concentration of the HCl aqueous solution is 37%, and then 0.5 g to 1.2 g of VTiAlC particles with a size less than 15 μm are added into the reaction agent to obtain a reactant.

3. The bimetallic VTi04 / VTiCT of claim 1 x The method for manufacturing a Schottky heterostructure is characterized in that: In the step one, the rotation speed of the polytetrafluoroethylene hydrothermal reactor is 300 rpm.

4. The bimetallic VTi04 / VTiCT of claim 1 x The method for manufacturing a Schottky heterostructure is characterized in that: In the step two, the concentration of the dilute HCl aqueous solution is 3.7%, and the dilute HCl aqueous solution is 150 mL.

5. The bimetallic VTi04 / VTiCT of claim 1 x The method for manufacturing a Schottky heterostructure is characterized in that: In the step two, the dilute HCl aqueous solution, the ethanol solution and the deionized water are respectively high-speed centrifuged for 3 to 5 times.

6. The bimetallic VTi04 / VTiCT of claim 1 x A method for producing a Schottky heterostructure, characterized in that: In the step two, the high-speed centrifugation is centrifugation at a rotation speed greater than 9000 rpm for 3 to 5 min, and the low-speed centrifugation is centrifugation at a rotation speed of 3000 to 4000 rpm for 3 to 5 min.

7. The bimetallic VTi04 / VTiCT of claim 1 x The method for manufacturing a Schottky heterostructure is characterized in that: The VTiCT in step three x The suspension concentration was 5-6 mg mL -1 .

8. The bimetallic VTi04 / VTiCT of claim 1 x The method for manufacturing a Schottky heterostructure is characterized by comprising the steps of: The temperature for vacuum drying of the reactants in step three is 75 o C.

9. The bimetallic VTi04 / VTiCT of claim 1 x The method for manufacturing a Schottky heterostructure is characterized by comprising the steps of: The step three in 430 o C~470 o Cannealing treatment to the powder.

10. The bimetallic VTi04 / VTiCT of any one of claims 1-9 x The method for manufacturing a Schottky heterostructure is characterized in that: The prepared bimetallic VTiO4 / VTiCT x The Schottky heterostructure serves as a lithium ion storage electrode material.

Images