Metal selenide (at) MXene composite material as well as preparation method and application thereof

Abstract

The invention discloses a metal selenide (at) MXene composite material and a preparation method and application thereof. The method comprises the following steps that 1, selenium powder and MAX are mixed, ground and mixed uniformly; and 2, calcining the product obtained in the step 1 in a protective atmosphere, and taking out the product after heat preservation to obtain the metal selenide and MXene composite material. The weight ratio of the selenium powder to the MAX phase is 10-1. And the MAX phase is any one of Ti2SnC, Ti2AlC, V2AlC, Cr2AlC, Ti2ZnC, Ti3AlC2, Mo2Ga2C, Ti3SiC2, V4AlC3 and (Ti < 0.5 > Nb < 0.5 >) < 5 > AlC4. The grinding time is 10-30 minutes. The preparation method disclosed by the invention is convenient, rapid and low in cost, can effectively utilize each component element in the MAX phase, does not generate pollution, and can realize large-scale industrial application; the prepared metal selenide (at) MXene composite electrode material has excellent interface bonding and can be applied to a secondary battery electrode material.

Description

Technical Field

[0001] The present invention relates to an electrode material and a preparation method and application thereof, and specifically to a metal selenide@MXene composite material and a preparation method and application thereof. Background Art

[0002] MXene is a general term for a class of two-dimensional transition metal carbons and / or nitrides with a layered structure similar to graphene. Its typical chemical form is M n+1 X n T z , where: M: early transition metal (such as Ti, V, Nb, etc.); X: carbon and / or nitrogen; T z : Surface functional groups (such as –OH, –F, –O, etc.). MXene is usually obtained by selectively etching the A-site element (A is a III-IV group element, such as Al, Si, Sn, etc.) from its precursor MAX phase using HF. MXene has high conductivity, high specific surface area, mechanical flexibility and adjustable chemical composition, making it very potential for application in the field of secondary batteries (such as Li / Na / K plasma batteries). However, the actual promotion of MXene in secondary battery applications is still limited by bottlenecks such as low specific capacity, layer stacking, and difficulty in large-scale preparation.

[0003] In order to improve the performance of MXene and address its bottlenecks, researchers often use a composite strategy to combine MXene with other materials, which can effectively improve the specific capacity and alleviate interlayer stacking. Although the composite strategy can improve the electrochemical performance of MXene, there are still some challenges in practical applications. For example, the bonding between MXene and other components in the composite material is not tight enough, which may lead to separation or detachment during the cycle and reduce the electrode performance. At the same time, the existing preparation process is complex and costly, making it difficult to achieve large-scale application. The safety and environmental protection issues of etching processes such as HF also limit industrialization. Summary of the invention

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a metal selenide @MXene composite material based on in-situ conversion with good interface bonding and good battery cycle performance. Another purpose of the present invention is to provide a metal selenide @MXene composite material that is pollution-free, convenient, fast and low-cost. Another purpose of the present invention is to provide an application of a metal selenide @MXene composite material in a negative electrode of a lithium-ion battery.

[0005] Technical solution: The method for preparing a metal selenide@MXene composite material based on in-situ conversion according to the present invention comprises the following steps:

[0006] Step 1: Mix selenium powder and MAX, grind and mix evenly;

[0007] Step 2: calcining the product obtained in step 1 in a protective atmosphere, taking it out after heat preservation, and obtaining a metal selenide@MXene composite material.

[0008] Furthermore, in step 1, the weight ratio of selenium powder to MAX phase is 10 to 1. The MAX phase is any one of Ti2SnC, Ti2AlC, V2AlC, Cr2AlC, Ti2ZnC, Ti3AlC2, and Ti3SiC2. The grinding time is 10 to 30 minutes. After mixing evenly, the mixture is loaded into a crucible.

[0009] Preferably, the weight ratio of selenium powder to MAX phase is 2.5, the MAX phase is Ti2SnC, and the grinding time is 10 minutes.

[0010] Furthermore, in step 2, the protective atmosphere is argon or nitrogen, the calcination temperature is 400-1000° C., the heating rate is 4-6° C. / min, and the holding time is 0.5-10 hours.

[0011] The present invention discloses a metal selenide@MXene composite material prepared by in-situ conversion.

[0012] The invention relates to the application of a metal selenide@MXene composite material in a negative electrode of a lithium-ion battery.

[0013] Preparation principle: The MX chemical bond in the MAX phase is stronger, while the MA chemical bond is weaker. Therefore, the A-position element easily reacts with selenium, which has strong oxidizing ability, to generate metal selenide in situ, and MX is converted into the corresponding MXene two-dimensional material. Since the reaction generates composite materials in situ, metal selenide and MXene have excellent interface bonding, which can give full play to the high capacity of metal selenide and the high conductivity of MXene, thus producing a 1+1>2 effect.

[0014] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0015] 1. The preparation method is convenient, fast, and low-cost. It can effectively utilize the various component elements in the MAX phase without causing pollution and can be applied in large-scale industries.

[0016] 2. The prepared metal selenide@MXene composite electrode material has excellent interface bonding and can be used as secondary battery electrode material;

[0017] 3. When the discharge current is 10A / g, the capacity reaches 148mAh / g. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a process flow chart of the present invention;

[0019] Figure 2 is a SEM image of the material obtained in the present invention;

[0020] Figure 3 This is a cycle performance diagram of the negative electrode material of a lithium ion battery obtained by the present invention. DETAILED DESCRIPTION

[0021] The materials, reagents, instruments, etc. used in the following examples are all commercially available unless otherwise specified. The experimental methods without specific conditions in the examples are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The average particle size of the selenium powder is 74 microns (200 mesh).

[0022] Example 1

[0023] like Figure 1 , a method for preparing a metal selenide@MXene composite material based on in-situ conversion, comprising the following steps:

[0024] (1) Selenium powder is mixed with MAX phase, and the weight ratio of selenium powder to MAX phase Ti2SnC is 2.5:1.

[0025] (2) Prepare mixed powder by grinding method, grind selenium powder and Ti2SnC for 10 minutes, mix them evenly and put them into crucible. The particle size of the mixed powder is not more than 74 microns (200 mesh).

[0026] (3) The crucible was placed in an atmosphere furnace and calcined in argon gas at a heating rate of 5°C / min to a calcination holding temperature of 550°C for 2 hours.

[0027] (4) After sintering, sampling is performed to obtain a metal selenide@MXene composite material.

[0028] like Figure 2 , metal selenide@MXene composite material, with metal selenide nanoparticles distributed on the MXene surface with a two-dimensional morphology. This morphology structure is conducive to alleviating the volume expansion of metal selenide during the process of lithium ion extraction / insertion, and has high conductivity, which is conducive to the full play of lithium storage performance.

[0029] Application Examples

[0030] The metal selenide@MXene composite material obtained in Example 1 was mixed with conductive carbon black and polyvinylidene fluoride in a mass ratio of 8:1:1 to form a slurry, and then evenly coated on a copper foil. After drying, it was cut into discs with a diameter of 12 mm (the active material surface loading was about 1 mg / cm 2), and then assembled with lithium metal and commercial electrolyte into a lithium-ion battery. The cycle performance test of the negative electrode material of the lithium-ion battery was carried out at a current density of 10A / g. Figure 3 It can be seen that after 500 cycles, the capacity is 148 mAh / g, and the capacity retention rate is greater than 93%.

[0031] Example 2

[0032] A method for preparing a metal selenide@MXene composite material based on in-situ conversion comprises the following steps:

[0033] (1) Mix selenium powder with MAX phase, and the weight ratio of selenium powder to MAX phase V2AlC is 2:1.

[0034] (2) Prepare mixed powder by grinding method, grind selenium powder and V2AlC for 10 minutes, mix them evenly and put them into crucible. The particle size of the mixed powder is not more than 74 microns (200 mesh).

[0035] (3) The crucible was placed in an atmosphere furnace and calcined in argon gas at a heating rate of 5°C / min to a calcination holding temperature of 700°C for 1 hour.

[0036] (4) After sintering, sampling is performed to obtain a metal selenide@MXene composite material.

[0037] Example 3

[0038] A method for preparing a metal selenide@MXene composite material based on in-situ conversion comprises the following steps:

[0039] (1) Selenium powder is mixed with MAX phase, and the weight ratio of selenium powder to MAX phase Ti3AlC2 is 4:1.

[0040] (2) Prepare mixed powder by grinding method, grind selenium powder and Ti3AlC2 for 10 minutes, mix them evenly and put them into crucible. The particle size of the mixed powder is not more than 74 microns (200 mesh).

[0041] (3) The crucible was placed in an atmosphere furnace and calcined in nitrogen at a heating rate of 5°C / min to a calcination holding temperature of 550°C for 2 hours.

[0042] (4) After sintering, sampling is performed to obtain a metal selenide@MXene composite material.

[0043] Example 4

[0044] A method for preparing a metal selenide@MXene composite material based on in-situ conversion comprises the following steps:

[0045] (1) Selenium powder is mixed with MAX phase, and the weight ratio of selenium powder to MAX phase Ti2AlC is 1:1.

[0046] (2) Prepare mixed powder by grinding method, grind selenium powder and Ti2AlC for 60 minutes, mix them evenly and put them into crucible. The particle size of the mixed powder is not more than 74 microns (200 mesh).

[0047] (3) The crucible was placed in an atmosphere furnace and calcined in nitrogen at a heating rate of 4°C / min to a calcination holding temperature of 400°C for 10 hours.

[0048] (4) After sintering, sampling is performed to obtain a metal selenide@MXene composite material.

[0049] Example 5

[0050] A method for preparing a metal selenide@MXene composite material based on in-situ conversion comprises the following steps:

[0051] (1) Selenium powder was mixed with MAX phase, and the weight ratio of selenium powder to MAX phase Cr2AlC was 10:1.

[0052] (2) Prepare mixed powder by grinding method, grind selenium powder and Cr2AlC for 30 minutes, mix them evenly and put them into crucible. The particle size of the mixed powder is not more than 74 microns (200 mesh).

[0053] (3) The crucible was placed in an atmosphere furnace and calcined in argon gas at a heating rate of 6°C / min to a calcination holding temperature of 1000°C for 0.5 h.

[0054] (4) After sintering, sampling is performed to obtain a metal selenide@MXene composite material.

[0055] Example 6

[0056] A method for preparing a metal selenide@MXene composite material based on in-situ conversion comprises the following steps:

[0057] (1) Selenium powder was mixed with MAX phase, and the weight ratio of selenium powder to MAX phase Ti2ZnC was 5:1.

[0058] (2) Prepare mixed powder by grinding method, grind selenium powder and Ti2ZnC for 20 minutes, mix them evenly and put them into crucible. The particle size of the mixed powder is not more than 74 microns (200 mesh).

[0059] (3) The crucible was placed in an atmosphere furnace and calcined in argon gas at a heating rate of 5°C / min to a calcination holding temperature of 800°C for 1 hour.

[0060] (4) After sintering, sampling is performed to obtain a metal selenide@MXene composite material.

[0061] Example 7

[0062] A method for preparing a metal selenide@MXene composite material based on in-situ conversion comprises the following steps:

[0063] (1) Selenium powder is mixed with MAX phase, and the weight ratio of selenium powder to MAX phase Ti3SiC2 is 8:1.

[0064] (2) Prepare mixed powder by grinding method, grind selenium powder and Ti3SiC2 for 460 minutes, mix them evenly and put them into crucible. The particle size of the mixed powder is not more than 74 microns (200 mesh).

[0065] (3) The crucible was placed in an atmosphere furnace and calcined in nitrogen at a heating rate of 6°C / min to a calcination holding temperature of 600°C for 8 hours.

[0066] (4) After sintering, sampling is performed to obtain a metal selenide@MXene composite material.

[0067] The Ti3SiC2 of this embodiment can be replaced by Ti2SnC, Ti2AlC, V2AlC, Cr2AlC, Ti2ZnC, Ti3AlC2, V4AlC3, (Ti 0.5 Nb 0.5 )5AlC4.

[0068] Comparative Example 1

[0069] The remaining steps of this comparative example are the same as those of Example 1, except that the weight ratio of selenium powder to MAX phase Ti2SnC in step 1 is adjusted to 0.5:1. The results show that a large amount of MAX phase does not participate in the reaction, and the product is a mixture of metal selenide @MXene and MAX phase, and the electrochemical performance is significantly reduced.

[0070] Comparative Example 2

[0071] The remaining steps of this comparative example are the same as those of Example 1, except that the weight ratio of selenium powder to MAX phase Ti2SnC in step 1 is adjusted to 12:1. The results show that MXene is also converted into metal selenide, which reduces the conductivity of the material and significantly reduces the electrochemical performance.

Claims

1. A method for preparing metal selenide@MXene composite materials based on in-situ conversion, characterized in that: The following steps are involved: Step 1: Mix selenium powder and MAX, grind and mix evenly; Step 2: calcining the product obtained in step 1 in a protective atmosphere, taking it out after heat preservation, and obtaining a metal selenide@MXene composite material.

2. The method for preparing a metal selenide@MXene composite material based on in-situ conversion according to claim 1, characterized in that: In the step 1, the weight ratio of selenium powder to MAX phase is 10-1.

3. The method for preparing a metal selenide@MXene composite material based on in-situ conversion according to claim 1, characterized in that: In the step 1, the MAX phase is Ti2SnC, Ti2AlC, V2AlC, Cr2AlC, Ti2ZnC, Ti3AlC2, Ti3SiC2, V4AlC3, (Ti 0.5 Nb 0.5 )5AlC4.

4. The method for preparing a metal selenide@MXene composite material based on in-situ conversion according to claim 1, characterized in that: In the step 1, the grinding time is 10 to 30 minutes.

5. The method for preparing metal selenide@MXene composite electrical materials based on in-situ conversion according to claim 1, characterized in that: In the step 1, the mixture is mixed evenly and then loaded into a crucible.

6. The method for preparing a metal selenide@MXene composite material based on in-situ conversion according to claim 1, characterized in that: In the step 2, the protective atmosphere is argon or nitrogen.

7. The method for preparing a metal selenide@MXene composite material based on in-situ conversion according to claim 1, characterized in that: In the step 2, the calcination temperature is 400-1000° C., and the heating rate is 4-6° C. / min.

8. The method for preparing a metal selenide@MXene composite material based on in-situ conversion according to claim 1, characterized in that: In the step 2, the heat preservation time is 0.5 to 10 hours.

9. The metal selenide@MXene composite material prepared by in-situ conversion according to any one of claims 1 to 8.

10. Use of a metal selenide@MXene composite material according to claim 9 in a negative electrode of a lithium-ion battery.

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