A Mo2CT x / Mo9O 26 Preparation method of quantum dot heterostructure electrode material

Abstract

The application belongs to the technical field of new energy and provides a Mo2CT x / Mo9O 26 Preparation method of quantum dot heterostructure electrode material, which uses organic quaternary ammonium cation as intercalation agent to pre-intercalate multilayer Mo2CT x MXene, and prepares few-layer Mo2CT x MXene. x Meanwhile, part of the few-layer Mo2CT 26 MXene is converted into Mo9O x quantum dot, and finally, few-layer Mo2CT 26 / Mo9O x quantum dot heterostructure negative electrode material is obtained. 26 In the prepared few-layer Mo2CT x / Mo9O 26 quantum dot heterostructure negative electrode material, the synergistic effect of few-layer Mo2CT ‑1 MXene and Mo9O ‑1 quantum dot makes it exhibit excellent cycle stability. After 100 cycles at a current density of 200 mAg, it exhibits an outstanding reversible specific capacity of 631.9 mAh g.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new energy, and particularly relates to a Mo2CT x / Mo9O 26 Preparation method of quantum dot heterostructure electrode material. BACKGROUND

[0002] With the continuous development of science and technology and the acceleration of modernization process, people's demand for energy is growing. However, traditional fossil energy is not only limited in reserves, but also pollutes the environment in the process of utilization, so it is particularly urgent to develop renewable clean energy. However, renewable clean energy generation is restricted by region and time, and has intermittency, which is difficult to guarantee continuous and stable energy supply. Therefore, the development of energy storage and conversion system has great significance for realizing efficient and stable supply of clean energy. Among many energy storage technologies, electrochemical energy storage has developed rapidly due to its high efficiency and convenience. At the same time, with the rapid development of various electronic devices and new energy electric vehicles, high-performance electrochemical energy storage devices have shown great commercial value. As an important part of electrochemical energy storage devices, electrode materials play an important role in the overall performance, so the development of high-performance electrode materials is the focus of current research.

[0003] In recent years, MXenes intercalation electrode materials have shown good application prospects in the field of electrochemical energy storage due to their unique two-dimensional layered structure, excellent electrical conductivity and adjustable surface end groups, and have gradually become candidates for high-performance new electrode materials. However, the specific capacity of MXenes material is low, and the restacking phenomenon is inevitable during charging and discharging. This restacking will limit the accessibility of ion storage sites on MXenes nanosheets and the transmission rate of ions, resulting in poor rate performance and rapid decay of specific capacity. Compared with Mo2CT x MXene material, Mo9O 26 has a higher theoretical specific capacity, but its electrical conductivity is relatively low and its cycle stability is poor. Therefore, the application provides a preparation method of Mo2CT x / Mo9O 26 quantum dot heterostructure electrode material. SUMMARY

[0004] The purpose of the application is to provide a preparation method of Mo2CT x / Mo9O 26 quantum dot heterostructure electrode material, which aims to solve the problems raised in the above background technology.

[0005] The purpose of the application is achieved by the following technical solutions:

[0006] A few-layer Mo2CTx / Mo9O 26 The application relates to a preparation method of a quantum dot heterostructure.

[0007] Step 1: a multilayer Mo2CT x MXene; the preparation step is: the powder is added into 40 mL of 12M HCl solution and uniformly mixed, then transferred into a Teflon lining of a 100 mL stainless steel autoclave for reaction; after the reaction is completed, the supernatant is repeatedly centrifuged and washed with pure water until the pH of the supernatant is greater than 6, and the precipitate is collected to obtain the multilayer Mo2CT x MXene;

[0008] Step 2: the multilayer Mo2CT x MXene prepared in step 1 is placed into 15 mL of 10% quaternary ammonium base solution, stirred at room temperature and then ultrasonically treated; after centrifugal cleaning, freeze-drying is carried out to obtain the few-layer Mo2CT x / Mo9O 26 The application relates to a quantum dot heterostructure electrode material.

[0009] Further, in step 1, the Mo2Ga2C powder is 400 mg.

[0010] Further, in step 1, the reaction temperature is 140 DEG C, and the reaction time is 8 days.

[0011] Further, in step 1, the centrifugal speed is not less than 5000 rpm, and the time is not less than 5 min.

[0012] Further, in step 2, the multilayer Mo2CT x MXene is 100-500 mg.

[0013] Further, in step 2, the quaternary ammonium base solution is tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), tetrapropylammonium hydroxide (TPAOH) or tetrabutylammonium hydroxide (TBAOH).

[0014] Further, in step 2, the stirring speed at room temperature is 200-500 rpm, the stirring time is 6-15 h, and the ultrasonic time is 1-3 h.

[0015] Further, in step 2, the specific process of centrifugal cleaning is: after 10-30 mL of deionized water is added, centrifugation is carried out at 9000-12000 rpm for 1 h, and the upper suspension liquid is removed; after the precipitate is dispersed into 10-50 mL of deionized water, centrifugation is carried out at 3500 rpm for 5 min, and the upper suspension liquid is collected.

[0016] A few-slice Mo2CT prepared according to the preparation method described above x / Mo9O 26 Quantum dot heterostructure.

[0017] A few-slice Mo2CT according to the above description x / Mo9O 26 Application of quantum dot heterostructures as anode materials for lithium-ion batteries.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. This invention provides a simple, economical, and efficient preparation method. This method uses ultrasound assistance to intercalate large-sized organic quaternary ammonium cations as intercalating agents for multilayer Mo2CT. x MXene undergoes pre-intercalation treatment, which significantly increases its interlayer spacing and weakens its interlayer van der Waals forces, thereby greatly expanding the electrolyte Li + With its transport and storage space, a few-layer Mo2CT with a large interlayer spacing was successfully fabricated. x MXene. Meanwhile, some few-slice Mo2CT... x MXene is transformed into Mo2CT through ultrasonic disruption and oxidation. x derivative Mo9O 26 Quantum dots ultimately yield few-layer Mo2CT x / Mo9O 26 Quantum dot heterostructure anode materials. Among them, few-layer Mo2CT x MXene acts as a conductive substrate, facilitating electron migration, upon which Mo9O is attached. 26 Quantum dots not only provide excellent column support but also suppress few-layer Mo2CT x The re-stacking of MXenes can also increase the number of charge storage sites.

[0020] 2. The few-slice Mo2CT prepared by this invention x / Mo9O 26 In quantum dot heterostructure anode materials, few-layer Mo2CT x MXene and Mo9O 26 The synergistic effect of quantum dots gives them excellent cycling stability. At 200 mA g... -1 After 100 cycles at a current density, it exhibited a capacity of 631.9 mAh g. -1 Excellent reversible specific capacity. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the mechanism of the present invention.

[0022] Figure 2 is the X-ray diffraction pattern of the sample prepared in Example 1.

[0023] Figure 3 is the transmission electron microscope image of the sample prepared in Example 1; wherein A is the low magnification transmission electron microscope image of the sample prepared in Example 1; B is the high magnification transmission electron microscope image of the sample prepared in Example 1.

[0024] Figure 4 is the atomic force microscope image of the sample prepared in Example 1; wherein A is the atomic force microscope image of the sample prepared in Example 1; B is the thickness information of the sample prepared in Example 1.

[0025] Figure 5 is the cycle stability and rate performance graph of the sample prepared in Example 1 as a lithium ion battery anode material. DETAILED DESCRIPTION

[0026] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the technical solutions of the present application will be described in detail below, but it should not be understood as limiting the scope of the implementation of the present application.

[0027] The specific implementation of the present application will be described in detail below in combination with specific embodiments.

[0028] Example 1: A Mo2CT x / Mo9O 26 Preparation method of quantum dot heterostructure anode material;

[0029] (1) Multilayer Mo2CT x Preparation of MXene: 400 mg of Mo2Ga2C powder was added to 40 mL of 12M HCl solution and mixed uniformly, then transferred to a 100 mL stainless steel autoclave Teflon liner, the reaction temperature was 140℃, and the reaction time was 8 days. After the reaction was completed, the supernatant was repeatedly washed with pure water for several times, the centrifugation time was 10 min, and the speed was 7000 rpm, until the pH of the supernatant was >6. The precipitate was collected to obtain multilayer Mo2CT x MXene.

[0030] (2) Few-layer Mo2CT x / Mo9O 26 Preparation of quantum dot heterostructure anode material: 200 mg of multilayer Mo2CT xMXene was transferred into 15 mL of 10% TBAOH solution, first stirred at 500 rpm for 12 h at room temperature, then ultrasonicated for 2 h. 20 mL of pure water was added, and centrifuged at 9900 rpm for 1 h to remove the upper suspension. The precipitate was dispersed into 40 mL of pure water, and centrifuged at 3500 rpm for 5 min to collect the upper suspension, which was freeze-dried for 4 days to obtain few-layer Mo2CT x / Mo9O 26 Quantum dot heterostructure negative electrode material.

[0031] Example 2: A Mo2CT x / Mo9O 26 Preparation method of quantum dot heterostructure negative electrode material;

[0032] Example 2 is different from Example 1 in that 200 mg of multi-layer Mo2CT x MXene was transferred into 15 mL of 10% TEAOH solution. Other steps and parameters were the same as those in Example 1, and finally few-layer Mo2CT x / Mo9O 26 Quantum dot heterostructure negative electrode material.

[0033] The X-ray diffraction pattern of the sample obtained in step (2) in Example 1 is shown in Figure 2 From Figure 2 it can be seen that the few-layer Mo2CT x / Mo9O 26 in the quantum dot heterostructure has a larger interlayer spacing x The (002) crystal plane of MXene corresponds to the diffraction peak at 5.51°, indicating that it has a larger interlayer spacing Figure 2 The diffraction peaks at 40.32° and 40.96° in 26 represent the (61-2) and (215) crystal planes of Mo9O

[0034] The transmission electron microscope image of the sample obtained in step (2) in Example 1 is shown in Figure 3 The transparency of the nanosheet with a lateral size of microns is higher, indicating that the few-layer Mo2CT x MXene is prepared. The few-layer Mo2CT x MXene is attached with spherical particles, and the average diameter of the spherical particles is 5.5 nm Figure 3 A). The interplanar spacing is The lattice fringes of the spherical particles correspond to the (106) crystal plane of Mo2CT x MXene. The interplanar spacing of the circular particles is and The lattice fringes of Mo9O are respectively related to Mo9O 26 The (61-2) and (215) crystal planes correspond to each other. Furthermore, the interplanar spacing is... and The lattice fringes of Mo9O are respectively related to Mo9O 26 The (51-2) and (214) crystal planes correspond to each other, indicating that the spherical particles are Mo9O. 26 Quantum dot( Figure 3 (Middle B). Proof of few-slice Mo2CT x / Mo9O 26 Successful synthesis of quantum dot heterostructures.

[0035] The atomic force microscope image of the sample obtained in step (2) of Example 1 is as follows: Figure 4 As shown. Few-slice Mo2CT x MXene has a two-dimensional planar structure with micron-scale lateral dimensions. Figure 4 (A). Measurement and analysis revealed that few-slice Mo2CT x The thickness of MXene is approximately 4.8 nm. Figure 4 (B) indicates that few-slice Mo2CT x Mo2CT in MXene x The MXene layer consists of four layers. This is a few-layer Mo2CT with micron-scale lateral dimensions. x MXene can endow electrode materials with more ion storage sites and excellent conductivity.

[0036] The multilayer Mo2CT obtained in step (1) of Example 1 x MXene and the few-slice Mo2CT obtained in step (2) x / Mo9O 26 The cycling stability and rate performance of quantum dot heterostructures are shown in the figure. Figure 5 As shown. Due to the small-slice Mo2CT x MXene acts as a conductive substrate, accelerating electron migration. Mo9O is attached to it. 26 Quantum dots not only provide excellent column support but also suppress few-layer Mo2CT x The re-stacking of MXenes can also increase the number of ion storage sites. (Small-layer Mo2CT) x / Mo9O 26 Quantum dot heterostructures at 200 mAg -1 After 100 cycles at a current density, it exhibited a capacity of 631.9 mAh g. -1 Its excellent reversible specific capacity is a key feature of multilayer Mo2CT. x Three times that of MXene. When the current density increases to 5C (2.5Ag) -1 When ), few-slice Mo2CT x / Mo9O26 The quantum dot heterostructure still exhibits a reversible specific capacity of 110.7 mAh g -1 The results show that the few-layer Mo2CT x / Mo9O 26 quantum dot heterostructure as a negative electrode material for lithium ion batteries has a more layer Mo2CT x MXene, and the cycle stability and rate performance are obviously improved.

[0037] The above is only the preferred embodiment of the present application, it should be pointed out that for those skilled in the art, without departing from the concept of the present application, can make several deformation and improvement, these should also be considered as the protection scope of the present application, these will not affect the effect and practicality of the patent of the present application.

Claims

1. A few-layer Mo2C x / Mo9O 26 A method for preparing a quantum dot heterostructure, characterized in that, The method comprises the following steps: Step 1, preparation of multilayer Mo2CT by hydrochloric acid etching method x MXene; the preparation steps are: 400 mg of Mo2Ga2C powder is added to 40 mL of 12M HCl solution and mixed uniformly, then transferred to a Teflon liner of a 100 mL stainless steel autoclave for reaction, the reaction temperature is 140°C, and the reaction time is 8 days; after the reaction is completed, repeatedly centrifugal washing with pure water until the supernatant pH>6, and collecting the precipitate to obtain multilayer Mo2CT x MXene; Step 2, 100-500 mg of the multi-layer Mo2CT prepared in step 1 x MXene was placed in 15 mL of 10% quaternary ammonium base solution, stirred at room temperature, and then ultrasonicated; after centrifugal washing, freeze-drying was performed to obtain few-layer Mo2CT x / Mo9O 26 Quantum dot heterostructure electrode material.

2. The production method according to claim 1, characterized by, In the step 1, the centrifugal speed is not less than 5000 rpm, and the time is not less than 5 min.

3. The preparation method according to claim 1, characterized in that, In the step 2, the quaternary ammonium base solution is tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide or tetrabutylammonium hydroxide.

4. The method of claim 1, wherein, In the step 2, the stirring speed at room temperature is 200-500 rpm, the stirring time is 6-15 h, and the ultrasonic time is 1-3 h.

5. The preparation method according to claim 1, characterized in that, In the step 2, the specific process of centrifugal washing is as follows: after adding 10-30 mL of deionized water, centrifuging at 9000-12000 rpm for 1 h to remove the upper suspension; after dispersing the precipitate into 10-50 mL of deionized water, centrifuging at 3500 rpm for 5 min to collect the upper suspension.

6. Few-layer Mo2C prepared by the method according to any one of claims 1 to 5 x quantum dot heterostructure. 26 quantum dot heterostructure.

7. A few-layer Mo2C1 according to claim 6 x / Mo9O 26 Application of quantum dot heterostructures as anode materials for lithium-ion batteries.

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