Binary and multi-element metal chalcogenide (at) MXenes heterojunction material, preparation method thereof and sodium ion battery

Abstract

The invention provides a binary and multi-element metal chalcogenide (at) MXenes heterojunction material, a preparation method thereof and a sodium ion battery, and relates to the technical field of sodium ion battery negative electrode materials. According to the method, multiple layers of MXenes materials are subjected to intercalation stripping and then subjected to high-temperature calcination with selenium powder and tellurium powder, and the metal chalcogenide (at) MXenes heterojunction material with regular morphology is obtained. The sodium ion battery prepared by taking the material as an active substance in a negative electrode material has the first specific discharge capacity of 845.89 mAh g <-1 > under the current density of 100mA g <-1 >, and still has the reversible specific discharge capacity of 340mAh g <-1 > after 50 cycles of charge and discharge.

Description

Technical Field

[0001] The present invention belongs to the technical field of negative electrode materials for sodium ion batteries, and specifically relates to a binary and multinary metal oxide compound @MXenes heterojunction material and a preparation method thereof, and a sodium ion battery. Background Art

[0003] Although lithium-ion batteries are currently widely used in electric vehicles, 3C products and other fields, the reserves of lithium resources are limited, the cost is high, and there is a risk of fire and explosion during the charging and discharging process of lithium-ion batteries, which makes it difficult for lithium-ion batteries to meet the high safety requirements of the energy storage field. Compared with lithium, sodium is abundant and has a price advantage. In addition, sodium-ion batteries also show low production costs, wide temperature range adaptability and outstanding safety. They have large-scale application potential in high-power density energy storage fields such as industrial peak-shaving energy storage batteries, photovoltaic and wind-volt matching energy storage, and grid frequency modulation. In addition, in order to meet the more stringent safety requirements of large-scale energy storage devices, aqueous sodium-ion batteries have also become a major research hotspot.

[0004] The development of high-performance sodium-ion battery energy storage batteries requires high-performance electrode materials. Especially in aqueous sodium-ion batteries, the aqueous electrolyte has a lower decomposition voltage (1.23V), which puts more stringent requirements on the properties of the electrode materials. Two-dimensional materials have unique physical and chemical properties and structural advantages, and have been widely studied as negative electrode materials for sodium-ion batteries. Since the transition metal carbonitride (MXenes) material was first discovered by Yury Gogostsi's team in 2011, it has attracted more and more attention as a special two-dimensional material due to its metallic conductivity, adjustable surface terminals and rich redox active metal atoms. Metal oxides are also an excellent two-dimensional material, and their large interlayer spacing is conducive to the diffusion and transport of ions. Therefore, combining MXenes with metal oxides is expected to give full play to the advantages of the two materials and promote the practical application of high-performance organic and aqueous sodium-ion batteries. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a binary and multi-metal oxide compound @MXenes heterojunction material and a preparation method thereof and a sodium ion battery. The present invention uses binary and multi-metal MXenes to derive a heterojunction material of a binary and multi-metal oxide compound and an original carbon layer. The synergistic effect between multiple materials can achieve more excellent physical and chemical properties, thereby facilitating the practical application of high-performance organic and aqueous sodium ion batteries.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of the present invention provides a method for preparing binary and multinary metal oxide compound @MXenes heterojunction materials, comprising the following steps:

[0008] (1) mixing and stirring the multilayer MXenes powder and the intercalation agent to obtain a suspension, and centrifuging the suspension to obtain a precipitated product;

[0009] (2) adding the precipitated product obtained in step (1) to deionized water for ultrasonication, then centrifuging to obtain a precipitate, and vacuum drying to obtain a product powder;

[0010] (3) Mixing the product powder obtained in step (2) with selenium powder or tellurium powder, and calcining under the protection of an inert gas to obtain the binary and multinary metal oxide compound @MXenes heterojunction material.

[0011] Furthermore, the multilayer MXenes powder in step (1) is one of the following binary and multi-component MXenes materials: TiVCT x 、TiNbCT x 、TiTaCT x , VNbCT x 、Ti 2 VC 2 T x 、Ti 2 Tc 2 T x 、Mo 2 TiC 2 T x 、Mo 2 Ti 2 C 3 T x .

[0012] Furthermore, the intercalant in step (1) is an aqueous solution of tetrabutylammonium hydroxide (TBOAH), and the concentration of the intercalant is 5 to 20 wt%.

[0013] Furthermore, in step (1), the mass volume ratio of the multilayer MXenes powder to the intercalation agent is 0.01 g / mL to 2 g / mL.

[0014] Furthermore, the ultrasonication time in step (2) is 0.5 to 2 hours.

[0015] Furthermore, the centrifugal speed in step (2) is 5000-10000 rpm, and the centrifugal time is 0.5-2 h.

[0016] Furthermore, in step (3), the mass ratio of the product powder to selenium powder or tellurium powder is 1:2 to 1:10.

[0017] Furthermore, the calcination temperature in step (3) is in the range of 450°C to 650°C, the calcination heating rate is in the range of 2°C / min to 5°C / min, and the calcination time is in the range of 2h to 4h.

[0018] The second aspect of the present invention provides a binary and multi-metal oxide compound @MXenes heterojunction material, which is prepared by the above-mentioned method of the present invention.

[0019] The third aspect of the present invention provides a sodium ion battery, wherein the active material in the negative electrode material of the sodium ion battery comprises the above-mentioned binary and multinary metal oxide compound@MXenes heterojunction material.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention provides a method for preparing binary and multinary metal oxide compounds @MXenes heterojunction materials. The method selects multilayer binary and multinary MXenes materials, first prepares a single layer of MXenes by intercalation and exfoliation, and then in situ grows on MXenes by calcination to obtain binary and multinary metal oxide compounds @MXenes heterojunction materials. MXenes have a unique layered structure. The enlarged interlayer spacing after intercalation is more conducive to the rapid insertion / extraction of ions. The controllable calcination temperature and calcination rate can also effectively suppress phase separation to obtain a uniform heterojunction material. Using MXenes as a template, the metal oxide compounds grown on its surface by calcination can form a three-dimensional conductive network structure to a certain extent by utilizing the similar coordination structure between the same transition metal elements, thereby enhancing the conductivity of the material.

[0022] 2. The present invention provides a sodium ion battery, wherein the active material in the negative electrode material of the sodium ion battery is a binary and multinary metal oxide compound @MXenes heterojunction material described in the present invention. The bond energy between selenium or tellurium and the metal in the oxide compound is small, and has a narrower band gap and line width. The larger radius of selenium atoms / tellurium atoms makes the metal selenide / telluride have a larger interlayer distance, which is beneficial to the diffusion and transport of ions. Its stronger intrinsic conductivity can also reduce the "adsorption" tendency between ions, achieve stronger electrochemical reversibility and faster charge transfer kinetics; the Mott-Schottky effect between the oxide compound and the MXenes metal-semiconductor heterojunction forms a built-in electric field at the heterojunction interface, providing power for the rapid transport of ions and electrons; the maintained layered structure can also alleviate the volume expansion of the electrode material during the charge and discharge process to a certain extent. The sodium ion battery, at 100mA g -1 At a current density of 1.34 W, the first discharge capacity reached 845.89 mAh g -1After 50 cycles of charge and discharge, there is still 342.48 mAh g -1 reversible discharge capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Mo prepared in Example 1 2 TiC 2 T x X-ray photoelectron spectroscopy (XPS) spectrum of @O@Se (denoted as MTC@O@Se, the same below): Figure (a) is the XPS spectrum of Mo 3d; Figure (b) is the XPS spectrum of Ti 2p.

[0024] Figure 2 This is a scanning electron microscope (SEM) image of MTC@O@Se prepared in Example 1.

[0025] Figure 3 This is a curve chart of 50 charge and discharge cycles of a CR2032 button battery assembled with MTC@O@Se prepared in Example 1 as the negative electrode material for a sodium ion battery.

[0026] Figure 4 This is a step charge and discharge cycle curve diagram of a CR2032 button battery assembled with MTC@O@Se prepared in Example 1 as the negative electrode material for a sodium ion battery at different current densities.

[0027] Figure 5 This is a curve chart of 50 charge and discharge cycles of a CR2032 button battery assembled with MTC@O prepared in Comparative Example 1 as the negative electrode material for a sodium ion battery.

[0028] Figure 6 This is a step charge and discharge cycle curve diagram of a CR2032 button battery assembled with MTC@O prepared in Comparative Example 1 as the negative electrode material for a sodium ion battery at different current densities. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. It is worth noting that the methods used in the present invention are conventional methods unless otherwise specified; the raw materials and devices used are conventional commercially available products unless otherwise specified, and their sources are not specifically limited.

[0030] The following is an example description:

[0031] The MXenes in the examples were purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.

[0032] The binary and multi-metal oxide compound @MXenes heterojunction materials and sodium ion batteries prepared in the examples were tested as follows:

[0033] (1) X-ray photoelectron spectroscopy (XPS) test: The instrument model is Thermo Scientific.

[0034] (2) Scanning electron microscope (SEM) test: The instrument is a field emission scanning electron microscope, model S4800, Hitachi, Japan.

[0035] (3) Charge and discharge test of CR2032 button cell assembled with sodium ion battery negative electrode material: The instrument is a Xinwei button cell charge and discharge tester, model CT-4008T-5V10Ma-164, purchased from Shenzhen Xinwei Electronics Co., Ltd.

[0036] Test method:

[0037] (1) A binary and multi-metal oxide compound @MXenes heterojunction material prepared in Examples 1 to 8 and Comparative Example 1 was used as the active material in the negative electrode material, Super P was used as the conductive agent, sodium carboxymethyl cellulose (CMC) was used as the binder, and the mass ratio of the active material, the conductive agent and the binder was 7:2:1. First, 70 mg of the active material and 20 mg of Super P were mixed in a mortar and dry ground for 30 min. Then, 500 μL of 20 mg mL -1 The CMC aqueous solution and 2 mL of distilled water were wet-grinded for 20 minutes. When the mixture showed a slight flow state when the mortar was tilted and there were no obvious large particles, it was transferred to the previously prepared carbon-coated copper foil. A scraper was used for coating, and the thickness was controlled to be 50 μm, and then it was dried at room temperature to prepare the negative electrode sheet.

[0038] (2) A sodium sheet with a diameter of 9 mm is nested in the center of the negative electrode shell, and a glass fiber diaphragm with a diameter of 16 mm is covered on top. Next, a mixed solution electrolyte with a concentration of 1M is dripped onto the diaphragm to ensure that the diaphragm is fully wetted. The electrolyte contains solid sodium perchlorate as a solute, and a mixture of ethylene carbonate (EC), fluoroethylene carbonate (FEC) and diethyl carbonate (DEC) as a solvent, with a volume ratio of EC:FEC:DEC=47.5:47.5:5. Subsequently, the negative electrode plate is reversed, with the active material side facing down, and precisely inverted in the center of the diaphragm. Finally, the positive electrode shell is tightly pressed on the negative electrode shell, and a plastic sealing machine is used to complete the packaging of the button battery.

[0039] (3) During the constant current charge and discharge test, the current density is 100mAg -1, the voltage range is 0.01V~3.00V.

[0040] (4) During the step charge and discharge test, the current density was 0.1A g -1 , 0.2A g -1 , 0.5A g -1 , 1.0Ag -1 , 2.0A g -1 and 5.0Ag -1 , the voltage range is 0.01V~3.00V.

[0041] Example 1

[0042] A method for preparing a quaternary metal oxide compound @MXenes heterojunction material, the method steps are as follows:

[0043] (1)Mo 2 TiC 2 T x MXenes powder and 10% TBOAH aqueous solution were mixed at a concentration of 0.1 g mL -1 and 100 μg / ml of the mixture, and the mixture is mixed with the mixture in a mass volume ratio and stirred sufficiently to obtain a suspension, and then the suspension is centrifuged to remove excess intercalant and retain a precipitated product;

[0044] (2) adding the precipitate obtained in step (1) to deionized water and ultrasonicating for 1 h, then centrifuging at 10,000 rpm for 1 h, then filtering the supernatant, and vacuum drying the precipitate to obtain a product powder;

[0045] (3) The product powder obtained in step (2) was mixed with selenium powder in a mass ratio of 1:4, and heated at 5°C min under inert gas protection. -1 The temperature was raised to 550° C. at a heating rate of 100° C. and calcined for 3 h to obtain a quaternary metal oxide compound @MXenes heterojunction material (MTC@O@Se) described in this embodiment.

[0046] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 1 was characterized by XPS. Figure 1 As shown in Figure (a), the XPS spectrum of Mo 3d, where the peaks of Mo-Se bond and Mo-OC can be observed; Figure (b) is the XPS spectrum of Ti 2p, where the peaks of Ti-O bond and Ti-Se bond can be observed. The XPS results show that in Mo 2 TiC 2 T x Oxides and selenides of Mo and Ti are formed on the surface.

[0047] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 1 was characterized by SEM. Figure 2 As shown, tiny oxide and selenide particles can be observed on the surface of the layered two-dimensional layer structure.

[0048] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 1 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to perform a constant current cycle charge and discharge performance test. -1 The coulombic efficiency and discharge specific capacity of 50 cycles of charge and discharge at a current density of Figure 3 As shown: The first discharge capacity is as high as 845.89 mAh g -1 After the first cycle of reaction, irreversible capacity decay occurred, and the reversible discharge capacity in the third cycle dropped to 397.67 mAh g -1 After 50 cycles of charge and discharge, the reversible capacity remained stable at 340 mAh g -1 .

[0049] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 1 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled. The step charge and discharge cycle performance was tested at different current densities. The results are as follows: Figure 4 As shown: When the current density is 0.1A -1 , 0.2Ag -1 , 0.5Ag -1 , 1.0A g -1 , 2.0Ag -1 and 5.0Ag -1 The average discharge capacity is 346.61 mAh g -1 、261.81mAh g -1 , 201.27mAh g -1 , 162.32mAh g -1 , 132.14mAh g -1 、96.77mAh g -1 The current density gradually recovered to 100 mA g -1 After that, the average discharge capacity is still 276.91mAh g -1 , and there was no serious damage to the material after cycling under high current.

[0050] Example 2

[0051] A method for preparing a quaternary metal oxide compound @MXenes heterojunction material, the method steps are as follows:

[0052] (1) TiVCTxMXenes powder and a 5% TBOAH aqueous solution were mixed at a concentration of 0.01 g mL-1 and 100 μg / ml of the mixture, and the mixture is mixed with the mixture in a mass volume ratio and stirred sufficiently to obtain a suspension, and then the suspension is centrifuged to remove excess intercalant and retain a precipitated product;

[0053] (2) adding the precipitate obtained in step (1) to deionized water and ultrasonicating for 2 h, then centrifuging at 7000 rpm for 1 h, then filtering the supernatant, and vacuum drying the precipitate to obtain a product powder;

[0054] (3) The product powder obtained in step (2) was mixed with selenium powder in a mass ratio of 1:2 and heated at 3 °C min -1 The temperature was raised to 600° C. at a heating rate of 100° C. and calcined for 2.5 h to obtain a quaternary metal oxide compound@MXenes heterojunction material described in this embodiment.

[0055] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 2 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to perform a constant current cycle charge and discharge performance test. -1 The first discharge capacity is as high as 765.76 mAh g -1 After the first week of reaction, irreversible capacity decay occurred. After 50 cycles of charge and discharge, the reversible capacity remained stable at 320 mAh g -1 .

[0056] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 2 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to test the step charge and discharge cycle performance at different current densities: when the current density was 0.1A -1 , 0.2Ag -1 , 0.5Ag -1 , 1.0A g -1 , 2.0A g -1 and 5.0A g -1 The average discharge capacity is 321.45 mAh g -1 , 243.23mAh g -1 , 189.34mAh g -1 , 153.12mAh g -1 , 129.34mAh g -1 , 91.23mAh g -1 The current density gradually recovered to 100 mA g -1 After that, the average discharge capacity is still 265.34 mAh g -1 , and there was no serious damage to the material after cycling under high current.

[0057] Example 3

[0058] A method for preparing a quaternary metal oxide compound @MXenes heterojunction material, the method steps are as follows:

[0059] (1) TiNbCTxMXenes powder and 10% TBOAH aqueous solution were mixed at a concentration of 1 g mL -1 and 100 μg / ml of the mixture, and the mixture is mixed with the mixture in a mass volume ratio and stirred sufficiently to obtain a suspension, and then the suspension is centrifuged to remove excess intercalant and retain a precipitated product;

[0060] (2) adding the precipitate obtained in step (1) to deionized water and ultrasonicating for 0.5 h, then centrifuging at 9000 rpm for 1 h, then filtering the supernatant, and vacuum drying the precipitate to obtain a product powder;

[0061] (3) The product powder obtained in step (2) was mixed with tellurium powder in a mass ratio of 1:6 and heated at 2 °C min -1 The temperature was raised to 650° C. at a heating rate of 100° C. and calcined for 3 h to obtain a quaternary metal oxide compound@MXenes heterojunction material described in this embodiment.

[0062] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 3 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to perform a constant current cycle charge and discharge performance test. -1 The first discharge capacity is as high as 810.23 mAh g -1 After the first week of reaction, irreversible capacity decay occurred. After 50 cycles of charge and discharge, the reversible capacity remained stable at 325 mAh g -1 .

[0063] The binary and multi-metal oxide compound @MXenes heterojunction materials prepared in Example 3 were used as active materials in the negative electrode materials of sodium ion batteries to assemble CR2032 button batteries, and the step charge-discharge cycle performance was tested at different current densities: when the current density was 0.1A g -1 , 0.2A g -1 , 0.5Ag -1 , 1.0Ag -1 , 2.0Ag -1 and 5.0Ag -1 The average discharge capacity is 333.23 mAh g -1 , 256.34mAh g -1 , 192.34mAh g -1 , 145.34mAh g -1 、130.23mAh g -1, 93.23mAh g -1 The current density gradually recovered to 100mAg -1 After that, the average discharge capacity is still 271.23 mAh g -1 , and there was no serious damage to the material after cycling under high current.

[0064] Example 4

[0065] A method for preparing a ternary metal oxide compound @MXenes heterojunction material, the method steps are as follows:

[0066] (1) TiTaCTxMXenes powder and 5% TBOAH aqueous solution were mixed at a concentration of 0.5 g mL -1 and 100 μg / ml of the mixture, and the mixture is mixed with the mixture in a mass volume ratio and stirred sufficiently to obtain a suspension, and then the suspension is centrifuged to remove excess intercalant and retain a precipitated product;

[0067] (2) adding the precipitate obtained in step (1) to deionized water and ultrasonicating for 1 h, then centrifuging at 5000 rpm for 1 h, then filtering the supernatant, and vacuum drying the precipitate to obtain a product powder;

[0068] (3) The product powder obtained in step (2) was mixed with selenium powder in a mass ratio of 1:10 and heated at 3 °C min -1 The temperature was raised to 450° C. at a heating rate of 100° C. and calcined for 4 hours to obtain a ternary metal oxide compound@MXenes heterojunction material described in this embodiment.

[0069] The ternary metal oxide compound @MXenes heterojunction material prepared in Example 4 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to perform a constant current cycle charge and discharge performance test. -1 The first discharge capacity is as high as 790.23 mAh g -1 After the first week of reaction, irreversible capacity decay occurred. After 50 cycles of charge and discharge, the reversible capacity remained stable at 321 mAh g -1 .

[0070] The ternary metal oxide compound @MXenes heterojunction material prepared in Example 4 was used as the active material in the negative electrode material of the sodium ion battery to assemble a CR2032 button battery, and the step charge and discharge cycle performance was tested at different current densities: when the current density was 0.1A -1 , 0.2Ag -1 , 0.5Ag -1 , 1.0A g -1 , 2.0A g -1 and 5.0A g-1 The average discharge capacity is 321.23 mAh g -1 , 254.98mAh g -1 , 189.34mAh g -1 、153.23mAh g -1 , 125.34mAh g -1 , 98.45mAh g -1 The current density gradually recovered to 100 mA g -1 After that, the average discharge capacity is still 280.45mAh g -1 , and there was no serious damage to the material after cycling under high current.

[0071] Example 5

[0072] A method for preparing a quaternary metal oxide compound @MXenes heterojunction material, the method steps are as follows:

[0073] (1) VNbCTxMXenes powder and 15% TBOAH aqueous solution were mixed at a concentration of 1 g mL -1 and 100 μg / ml of the mixture, and the mixture is mixed with the mixture in a mass volume ratio and stirred sufficiently to obtain a suspension, and then the suspension is centrifuged to remove excess intercalant and retain a precipitated product;

[0074] (2) adding the precipitate obtained in step (1) to deionized water and ultrasonicating for 2 h, then centrifuging at 6000 rpm for 1 h, then filtering the supernatant, and vacuum drying the precipitate to obtain a product powder;

[0075] (3) The product powder obtained in step (2) was mixed with selenium powder in a mass ratio of 1:3 and heated at 4 °C min -1 The temperature was raised to 500° C. at a heating rate of 100° C. and calcined for 2 h to obtain a quaternary metal oxide compound@MXenes heterojunction material described in this embodiment.

[0076] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 5 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to perform a constant current cycle charge and discharge performance test. -1 The first discharge capacity is as high as 799.23 mAh g -1 After the first week of reaction, irreversible capacity decay occurred. After 50 cycles of charge and discharge, the reversible capacity remained stable at 312 mAh g -1 .

[0077] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 5 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to test the step charge and discharge cycle performance at different current densities: when the current density was 0.1A -1 , 0.2Ag -1 , 0.5Ag -1 , 1.0A g -1 , 2.0A g -1 and 5.0Ag -1 The average discharge capacity is 314.34 mAh g -1 , 265.34mAh g -1 、175.56mAh g -1 , 154.34mAh g -1 , 129.34mAh g -1 、100.34mAh g -1 The current density gradually recovered to 100mAg -1 After that, the average discharge capacity is still 276.34 mAh g -1 , and there was no serious damage to the material after cycling under high current.

[0078] Example 6

[0079] A method for preparing a quaternary metal oxide compound @MXenes heterojunction material, the method steps are as follows:

[0080] (1) Ti 2 VC 2 TxMXenes powder and 20% TBOAH aqueous solution were mixed at a concentration of 2 g mL -1 and 100 μg / ml of the mixture, and the mixture is mixed with the mixture in a mass volume ratio and stirred sufficiently to obtain a suspension, and then the suspension is centrifuged to remove excess intercalant and retain a precipitated product;

[0081] (2) adding the precipitate obtained in step (1) to deionized water and ultrasonicating for 1.5 hours, centrifuging at 8000 rpm for 1 hour, then filtering the supernatant, and vacuum drying the precipitate to obtain a product powder;

[0082] (3) The product powder obtained in step (2) was mixed with tellurium powder in a mass ratio of 1:5 and heated at 3 °C min -1 The temperature was raised to 550° C. at a heating rate of 100° C. and calcined for 3 h to obtain a quaternary metal oxide compound@MXenes heterojunction material described in this embodiment.

[0083] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 6 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to perform a constant current cycle charge and discharge performance test. -1 The first discharge capacity is as high as 803.23 mAh g -1 After the first week of reaction, irreversible capacity decay occurred. After 50 cycles of charge and discharge, the reversible capacity remained stable at 318 mAh g -1 .

[0084] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 6 was used as the active material in the negative electrode material of the sodium ion battery to assemble a CR2032 button battery, and the step charge and discharge cycle performance was tested at different current densities: when the current density was 0.1A g -1 , 0.2Ag -1 , 0.5Ag -1 , 1.0Ag -1 , 2.0A g -1 and 5.0Ag -1 The average discharge capacity is 313.23 mAh g -1 , 270.34mAh g -1 、170.23mAh g -1 、155.28mAh g -1 、130.56mAh g -1 , 94.34mAh g -1 The current density gradually recovered to 100mAg -1 After that, the average discharge capacity is still 265.45mAh g -1 , and there was no serious damage to the material after cycling under high current.

[0085] Example 7

[0086] A method for preparing a ternary metal oxide compound @MXenes heterojunction material, the method steps are as follows:

[0087] (1) Ti 2 Tc 2 T x MXenes powder and 20% TBOAH aqueous solution were mixed at 1 g mL -1 and 100 μg / ml of the mixture, and the mixture is mixed with the mixture in a mass volume ratio and stirred sufficiently to obtain a suspension, and then the suspension is centrifuged to remove excess intercalant and retain a precipitated product;

[0088] (2) adding the precipitate obtained in step (1) to deionized water and ultrasonicating for 2 h, then centrifuging at 9000 rpm for 1 h, then filtering the supernatant, and vacuum drying the precipitate to obtain a product powder;

[0089] (3) The product powder obtained in step (2) was mixed with selenium powder in a mass ratio of 1:7 and heated at 2°C min -1 The temperature was raised to 600° C. at a heating rate of 100° C. and calcined for 4 hours to obtain a ternary metal oxide compound@MXenes heterojunction material described in this embodiment.

[0090] The ternary metal oxide compound @MXenes heterojunction material prepared in Example 7 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to perform a constant current cycle charge and discharge performance test. -1 The first discharge capacity is as high as 787.45 mAh g -1 After the first week of reaction, irreversible capacity decay occurred. After 50 cycles of charge and discharge, the reversible capacity remained stable at 309 mAh g -1 .

[0091] The ternary metal oxide compound @MXenes heterojunction material prepared in Example 7 was used as the active material in the negative electrode material of the sodium ion battery to assemble a CR2032 button battery, and the step charge and discharge cycle performance was tested at different current densities: when the current density was 0.1A -1 , 0.2Ag -1 , 0.5Ag -1 , 1.0A g -1 , 2.0A g -1 and 5.0A g -1 The average discharge capacity is 324.34 mAh g -1 , 278.45mAh g -1 , 171.45mAh g -1 , 157.86mAh g -1 , 131.33mAh g -1 , 97.89mAh g -1 The current density gradually recovered to 100 mA g -1 After that, the average discharge capacity is still 272.23mAh g -1 , and there was no serious damage to the material after cycling under high current.

[0092] Example 8

[0093] A method for preparing a quaternary metal oxide compound @MXenes heterojunction material, the method steps are as follows:

[0094] (1)Mo 2 Ti 2 C 3 Tx MXenes powder and 10% TBOAH aqueous solution were mixed at a concentration of 0.4 g mL -1 and 100 μg / ml of the mixture, and the mixture is mixed with the mixture in a mass volume ratio and stirred sufficiently to obtain a suspension, and then the suspension is centrifuged to remove excess intercalant and retain a precipitated product;

[0095] (2) adding the precipitate obtained in step (1) to deionized water and ultrasonicating for 1 h, then centrifuging at 5000 rpm for 1 h, then filtering the supernatant, and vacuum drying the precipitate to obtain a product powder;

[0096] (3) The product powder obtained in step (2) was mixed with tellurium powder in a mass ratio of 1:3 and heated at 3 °C min -1 The temperature was raised to 450° C. at a heating rate of 100° C. and calcined for 2 h to obtain a quaternary metal oxide compound@MXenes heterojunction material described in this embodiment.

[0097] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 8 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to perform a constant current cycle charge and discharge performance test. -1 The first discharge capacity is as high as 765.34 mAh g -1 After the first week of reaction, irreversible capacity decay occurred. After 50 cycles of charge and discharge, the reversible capacity remained stable at 314 mAh g -1 .

[0098] The quaternary metal oxide compound @MXenes heterojunction material prepared in Example 8 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to test the step charge and discharge cycle performance at different current densities: when the current density was 0.1A -1 , 0.2Ag -1 , 0.5Ag -1 , 1.0A g -1 , 2.0A g -1 and 5.0Ag -1 The average discharge capacity is 319.34 mAh g -1 , 281.23mAh g -1 、172.66mAh g -1 , 159.34mAh g -1 、132.33mAh g -1 , 96.34mAh g -1 The current density gradually recovered to 100mAg-1 After that, the average discharge capacity is still 267.34 mAh g -1 , and there was no serious damage to the material after cycling under high current.

[0099] Comparative Example 1

[0100] This comparative example provides a method for preparing a binary metal oxide compound @MXenes heterojunction material, which is different from Example 1 in that selenium powder does not participate in the solid phase sintering process. The specific method steps are as follows:

[0101] (1)Mo 2 TiC 2 T x MXenes powder and 10% TBOAH aqueous solution were mixed at a concentration of 0.1 g mL -1 and 100 μg / ml of the mixture, and the mixture is mixed with the mixture in a mass volume ratio and stirred sufficiently to obtain a suspension, and then the suspension is centrifuged to remove excess intercalant and retain a precipitated product;

[0102] (2) adding the precipitate obtained in step (1) to deionized water and ultrasonicating for 1 h, then centrifuging at 10,000 rpm for 1 h, then filtering the supernatant, and vacuum drying the precipitate to obtain a product powder;

[0103] (3) Under the protection of inert gas, the product powder obtained in step (2) was heated at 5°C min -1 The temperature was raised to 550° C. at a heating rate of 100° C. and calcined for 3 h to obtain a binary metal oxide compound@MXenes heterojunction material (MTC@O) described in this comparative example.

[0104] The binary metal oxide compound @MXenes heterojunction material prepared in Comparative Example 1 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled to perform a constant current cycle charge and discharge performance test. -1 The coulombic efficiency and discharge specific capacity of 50 cycles of charge and discharge at a current density of Figure 5 As shown: The first discharge capacity is only 270.10 mAh g -1 After the first cycle of reaction, irreversible capacity decay occurred, and the reversible discharge capacity in the second cycle dropped to 144.09 mAh g -1 After 50 cycles of charge and discharge, the reversible capacity remained stable at 116.70 mAh g -1 Compared with Example 1, the initial specific capacity and the subsequent discharge specific capacity in 50 cycles are lower. This shows that the introduction of selenium powder significantly improves the electrochemical performance of VO2(B) material.

[0105] The binary metal oxide compound @MXenes heterojunction material prepared in Comparative Example 1 was used as the active material in the negative electrode material of the sodium ion battery, and a CR2032 button battery was assembled. The step charge and discharge cycle performance was tested at different current densities. The results are as follows: Figure 6 As shown: When the current density is 0.1A -1 , 0.2Ag -1 , 0.5Ag -1 , 1.0Ag -1 , 2.0Ag -1 and 5.0Ag -1 The average discharge capacity is 125.58 mAh g -1 , 90.72mAh g -1 、67.21mAh g -1 , 54.72mAh g -1 , 42.79mAh g -1 , 25.01mAh g -1 The current density gradually recovered to 100mAg -1 After that, the average discharge capacity is 108.23 mAh g -1 It was found that after cycling at high current, although the material did not produce serious irreversible capacity damage, the discharge specific capacity of the material at high current was too low.

[0106] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing binary and multi-metal oxide compound @MXenes heterojunction materials, comprising the following steps: (1) mixing and stirring the multilayer MXenes powder and the intercalation agent to obtain a suspension, and centrifuging the suspension to obtain a precipitated product; (2) adding the precipitated product obtained in step (1) to deionized water for ultrasonication, then centrifuging to obtain a precipitate, and vacuum drying to obtain a product powder; (3) Mixing the product powder obtained in step (2) with selenium powder or tellurium powder, and calcining under the protection of an inert gas to obtain the binary and multinary metal oxide compound @MXenes heterojunction material.

2. The preparation method according to claim 1, characterized in that: The multilayer MXenes powder in step (1) is one of the following binary and multi-component MXenes materials: TiVCT x 、TiNbCT x 、TiTaCT x , VNbCT x 、Ti2VC2T x 、Ti2TaC2T x 、Mo2TiC2T x 、Mo2Ti2C3T x .

3. The preparation method according to claim 1, characterized in that: The intercalation agent in step (1) is an aqueous solution of tetrabutylammonium hydroxide, and the concentration of the intercalation agent is 5-20wt%.

4. The preparation method according to claim 1, characterized in that: The mass volume ratio of the multilayer MXenes powder to the intercalation agent in step (1) is 0.01 g / mL to 2 g / mL.

5. The preparation method according to claim 1, characterized in that: The ultrasonic time in step (2) is 0.5 to 2 hours, the centrifugal speed is 5000 to 10000 rpm, and the centrifugal time is 0.5 to 2 hours.

6. The preparation method according to claim 1, characterized in that: The mass ratio of the product powder to selenium powder or tellurium powder in step (3) is 1:2 to 1:

10.

7. The preparation method according to claim 1, characterized in that: The calcination temperature in step (3) is in the range of 450°C to 650°C, the calcination heating rate is in the range of 2°C / min to 5°C / min, and the calcination time is in the range of 2h to 4h.

8. A binary and multinary metal oxide compound @MXenes heterojunction material, characterized in that: The method is prepared by any one of claims 1 to 7.

9. A sodium ion battery, characterized in that: The active material in the sodium ion battery negative electrode material comprises the binary and multi-metal oxide compound@MXenes heterojunction material as described in claim 8.

Images