Preparation method and application of MXene / Sn composite material

Abstract

The invention relates to the technical field of an electrode composed of an active material or comprising the active material, in particular to a preparation method and application of an MXene / Sn composite material. The invention provides a preparation method of an MXene / Sn composite material, which comprises the following steps of: S101, preparing porous tin: in an inert gas or vacuum environment, atomizing molten tin alloy gas to obtain solid powder particles, and etching by using acid or alkali to obtain the porous tin; s102, porous tin surface treatment: carrying out surface oxidation treatment on the porous tin obtained in the step S101 to form tin dioxide sites or thin layers on the surface of the porous tin; s201, MXene is prepared and obtained; s202, surface modification of MXene: MXene obtained in S201 is treated with hydrogen peroxide, and then carboxyl or amino is introduced; and S3, porous tin and MXene are compounded, the dispersion liquid of the porous tin obtained through treatment in the step 102 is mixed with the dispersion liquid of the MXene subjected to surface modification in the step 202, and compounding is completed through electrostatic attraction. The self-agglomeration phenomenon in the charging and discharging process can be inhibited, and the high energy density is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrodes composed of or including active materials, and in particular to a preparation method and application of a MXene / Sn composite material. Background Art

[0002] Sodium-ion batteries (SIBs) have become one of the most promising candidate technologies for large-scale energy storage systems due to their raw material abundance (the Earth's crust contains 2.74% sodium, compared to 0.0065% lithium) and cost advantages (aluminum foil can be used instead of copper foil for the anode current collector, reducing material costs by over 40%). However, technical bottlenecks in anode materials severely hinder their commercialization: ① Conventional lithium-ion graphite anodes cannot effectively store sodium (theoretical capacity <35 mAh / g) due to the limited interlayer spacing (0.335 nm); ② While mainstream hard carbon materials can achieve a reversible capacity of 300 mAh / g, their inherently low compaction density (typically <1.0 g / cm³) limits the electrode areal density, contributing to the low energy density of current battery cells.

[0003] Tin-based materials are considered as a breakthrough direction for high energy density sodium anodes due to their theoretical specific capacity of up to 847 mAh / g (about 2.8 times that of hard carbon materials) and suitable sodium storage potential (0.2-0.5 V vs Na / Na+). However, there are two key failure mechanisms in this material system: (1) the drastic volume expansion caused by the alloying reaction (Na 15 The volume expansion rate of Sn4 during phase transition is ≥420%), which causes the active material particles to pulverize and separate from the current collector (the capacity retention rate is usually <30% after 20 cycles); (2) the spontaneous agglomeration of tin particles during the charge and discharge process (the average particle size increases by 3-5 times after 50 cycles), which not only accelerates the structural collapse but also causes the ion diffusion path to be extended (DNa + drops to the order of 10-14 cm² / s), causing severe polarization effects.

[0004] To address these issues, current methods for improving tin-based negative electrode materials can be classified into nano-scaling strategies, structural engineering, and composite system construction.

[0005] In the field of composite system construction, MXene materials are considered a new generation of coating and modification materials due to their unique two-dimensional layered structure (typical interlayer spacing of 1.2-1.5nm), intrinsically high conductivity (in-plane conductivity ≥6000S / cm), and abundant surface functional groups (such as -OH and -O). MXene also possesses excellent mechanical properties. Calculations show that when stretched along the MXene base plane, its Young's modulus can reach 0.33TPa. The material's surface end groups have a large critical strain, which inhibits the collapse of the surface metal layer under tensile stress and enhances the MXene's flexibility. Summary of the Invention

[0006] In response to the spontaneous agglomeration phenomenon of tin-based materials in the prior art during the charge and discharge process, the present invention provides a preparation method and application of a MXene / Sn composite material, which can inhibit the spontaneous agglomeration phenomenon during the charge and discharge process and has a higher energy density.

[0007] The present invention provides a preparation method of a MXene / Sn composite material, comprising the following steps: S101, preparing porous tin, in an inert gas or vacuum environment, atomizing a molten tin alloy to obtain solid powder particles, and then etching with an acid or alkali to obtain porous tin; S102, surface treatment of the porous tin, oxidizing the surface of the porous tin obtained in S101 to form tin dioxide sites or a thin layer on the surface; S201, preparing MXene; S202, surface modification of the MXene, introducing carboxyl groups or amino groups into the MXene obtained in S201 through hydrogen peroxide treatment; S3, compounding the porous tin and MXene, mixing a dispersion of the porous tin obtained by the treatment in S102 with a dispersion of the MXene after the surface modification in S202, and completing the compounding by electrostatic attraction.

[0008] Furthermore, in step S101, the particle size of the solid powder particles is 400-600 nm.

[0009] Furthermore, in step S101, the aluminum-germanium-tin alloy is smelted, the smelted alloy is gas-atomized, and after the gas atomization, the alloy is cooled to room temperature and then etched with hydrochloric acid, and then washed with water to remove residual acid.

[0010] Furthermore, in S102, the surface treatment method of the porous tin is: the porous tin prepared in S101 is heated in an air environment at a temperature of 150-250°C for 5-10 minutes.

[0011] Furthermore, in S102, the surface treatment method of the porous tin is as follows: the porous tin prepared in S101 is soaked in a mixed solution of sulfuric acid and hydrogen peroxide.

[0012] Furthermore, S201, the preparation method of MXene is: using lithium fluoride and hydrochloric acid to MAX phase (Ti3C2T X ) for etching, the etching time is 12~72h, the etching temperature is 25~40℃, the stirring rate is 100~800rpm, the solid-liquid ratio is 1g:10~20mL, and the MXene is washed and separated after etching.

[0013] Furthermore, in S201, the MXene is subjected to layered exfoliation, using dimethyl sulfoxide (DMSO) or tetramethylammonium hydroxide (TMAOH) as an intercalating agent to assist ultrasonic exfoliation, and the separated solution is centrifuged to remove unexfoliated MXene multilayer particles.

[0014] Furthermore, S202, the method for MXene surface modification is: slowly adding hydrogen peroxide to the MXene aqueous solution obtained in S201 and stirring to react; mixing APTES (γ-aminopropyltriethoxysilane) with water and stirring to hydrolyze; adding the MXene dispersion to the APTES hydrolyzate to react, and then centrifuging the dispersion and washing it multiple times to remove unreacted APTES.

[0015] Furthermore, S3, the method for composite of porous tin and MXene is as follows: the porous tin obtained by treatment with S102 is dispersed in water and ultrasonically dispersed; MXene is added thereto (according to the mass ratio of MXene:Sn=1:1.1~1.3); the two are mixed, the pH is adjusted to 3~4 and then stirred, and after the stirring is completed, the unbound porous tin particles and the supernatant are removed by centrifugation, and finally the composite MXene / Sn composite material is freeze-dried.

[0016] The present invention also provides a battery, in which the MXene / Sn composite material prepared as above is applied to the preparation of battery electrode materials.

[0017] The beneficial effects of the present invention are: Compared with hard carbon negative electrodes, the MXene / Sn composite material described in the present invention can significantly improve the energy density of the battery cell.

[0018] This invention combines porous tin (metallic tin or a surface layer containing SnO2) with MXene. The porous structure buffers volume expansion, while the MXene coating inhibits particle agglomeration. Micro-oxidation of the tin surface forms a thin SnO2 layer, improving conductivity and interfacial bonding. Selective etching of the porous tin creates a buffer space within the particles to mitigate volume expansion, effectively extending cycle life. The MXene / Sn composite is achieved at room temperature, avoiding the destruction of the porous tin structure caused by high-temperature carbon coating.

[0019] The high modulus of the MXene coating and the critical strain characteristics of its surface end groups form a mechanically adaptive network, inhibiting the shedding of active materials. APTES alkylation treatment, followed by H2O2 pre-oxidation, enhances MXene dispersibility and interfacial compatibility. The surface groups strengthen the binding between MXene and tin, significantly reducing the interfacial resistance of the composite. Electrostatic adsorption between the porous tin oxide layer (SnO2) and the modified MXene (-NH2 functional groups) is regulated by a pH 3-4 environment, achieving a strong interfacial bond. The two-dimensional MXene sheets physically isolate the porous tin particles, inhibiting the surface migration of tin atoms during charge and discharge, significantly reducing particle size growth during cycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0021] Figure 1 This is a process flow chart of the preparation method of the MXene / Sn composite material of the present invention.

[0022] Figure 2 This is a typical parameter diagram of the material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0024] like Figure 1 As shown, Example 1 of the present invention provides a method for preparing a MXene / Sn composite material, comprising the following steps: Preparation of S101 porous tin. An aluminum-germanium-tin alloy containing 95.3% tin, 3.5% germanium, and 1.2% aluminum is melted. The raw metal purity should be ≥99.99%. The alloy is melted at 800°C under a protective atmosphere of helium and hydrogen, with the hydrogen content accounting for 2%. The melted metal is atomized. A high-speed gas stream impinges on the molten metal. The collisions convert the kinetic energy of the gas into the surface energy of the molten metal, breaking the molten metal stream into fine droplets. These droplets are then rapidly cooled and solidified in the airflow atmosphere to form powder particles. The atomization pressure and liquid flow rate are adjusted based on the powder particle size, which should be between 400 and 600 nm. The atomization medium is helium and hydrogen, with the hydrogen content accounting for 2%. After cooling the metal particles to room temperature, the alloy is etched with 1 mol / L hydrochloric acid for 12 hours at room temperature. The material is then washed with water to remove any residual acid.

[0025] S102: Surface treatment of porous tin: The porous tin obtained in S101 is heated at 150-250° C. in an air environment for 5-10 minutes. In this embodiment, the temperature is 150° C. for 10 minutes to slightly oxidize the surface of the porous tin to generate tin dioxide.

[0026] S201 Ti3C2T XThe powder was mixed with an etchant consisting of a mixture of lithium fluoride and hydrochloric acid. The lithium fluoride concentration in the mixture was 1.6 M, and the hydrochloric acid concentration was 9 M. The etching time was 24 h, the stirring rate was 200 rpm, and the ratio of MAX phase powder to etchant was 1 g:15 mL. After etching, the MXene was washed with deionized water until the pH of the supernatant was 5-6. The MXene was separated by centrifugation. The MXene was then exfoliated using dimethyl sulfoxide (DMSO) or tetramethylammonium hydroxide (TMAOH) as an intercalation agent to assist ultrasonic exfoliation for 30-60 min at a power of 100-200 W. The separated solution was then centrifuged at low speed to remove unexfoliated MXene multilayer particles.

[0027] S202 MXene surface modification. Slowly add hydrogen peroxide to the MXene aqueous solution prepared in S201 and stir at 60°C–80°C for 2–4 hours. Mix APTES (γ-aminopropyltriethoxysilane) and water in a 1:9 volume ratio (pH = 5, adjusted with acetic acid) and stir for 10 minutes. Add the MXene dispersion to the APTES hydrolyzate and reflux at 70°C for 12 hours. The dispersion is then centrifuged and washed multiple times to remove unreacted APTES.

[0028] S3 Porous tin and MXene composite. Oxidized porous tin was dispersed in water and ultrasonically dispersed for 30 minutes. MXene was then added (at a mass ratio of MXene to Sn = 1:1.2). The mixture was mixed and the pH adjusted to 3-4. Magnetic stirring was performed for 12 hours. After stirring, unbound particles and the supernatant were removed by low-speed centrifugation. Finally, the MXene / Sn composite was freeze-dried to obtain the final product.

[0029] Example 2: This example differs from Example 1 in that, in S102, the surface treatment method of the porous tin is as follows: the porous tin prepared in S101 is immersed in a mixed solution of sulfuric acid and hydrogen peroxide.

[0030] Example 3: This example differs from Example 1 in that, in S201, lithium fluoride and hydrochloric acid are used to treat the MAX phase (Ti3C2T X ) for etching, the etching time was 12 h, the etching temperature was 25 ° C, the stirring rate was 100 rpm, the solid-liquid ratio was 1 g: 10 mL, and the MXene was washed and separated after etching.

[0031] Example 4: This example differs from Example 1 in that, in S201, lithium fluoride and hydrochloric acid are used to treat the MAX phase (Ti3C2T X ) for etching, the etching time was 72 h, the etching temperature was 40 ° C, the stirring rate was 800 rpm, the solid-liquid ratio was 1 g: 20 mL, and the MXene was washed and separated after etching.

[0032] Example 5: This example differs from Example 1 in that, in S102, the porous tin is surface treated by heating the porous tin obtained in S101 at 200° C. in an air environment for 8 minutes.

[0033] Example 6: This example differs from Example 1 in that, in S102, the porous tin is surface treated by heating the porous tin obtained in S101 at 250° C. in an air environment for 5 minutes.

[0034] Example 7. The difference between this example and Example 1 is that S3 porous tin and MXene are compounded, and MXene is added according to a mass ratio of MXene:Sn=1:1.1.

[0035] Example 8. The difference between this example and Example 1 is that S3 porous tin and MXene are compounded, and MXene is added according to the mass ratio of MXene:Sn=1:1.3.

[0036] Typical parameters of the materials prepared in Example 1 are as follows Figure 2 shown.

[0037] Example 9 of the present invention provides a battery, in which the MXene / Sn composite material prepared as described above is applied to the preparation of a negative electrode material for the battery.

[0038] Although the present invention has been described in detail with reference to the accompanying drawings and in conjunction with preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, persons of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any changes or substitutions that can be easily conceived by persons skilled in the art within the technical scope disclosed in the present invention shall be within the scope of protection of the present invention.

Claims

1. A method for preparing a MXene / Sn composite material, characterized in that: The following steps are involved: S101, preparing porous tin, atomizing a molten tin alloy under an inert gas or vacuum environment to obtain solid powder particles, and then etching with acid or alkali to obtain porous tin; S102, surface treatment of the porous tin, oxidation treatment of the surface of the porous tin obtained in S101, to form tin dioxide sites or a thin layer on the surface; S201, preparing MXene; S202, MXene surface modification, the MXene obtained in S201 is treated with hydrogen peroxide and then carboxyl groups or amino groups are introduced; S3, porous tin and MXene are composited. The porous tin dispersion obtained by S102 treatment is mixed with the MXene dispersion surface-modified by S202, and the composite is completed by electrostatic attraction.

2. The method for preparing a MXene / Sn composite material according to claim 1, wherein: In step S101, the particle size of the solid powder particles is 400-600 nm.

3. The method for preparing a MXene / Sn composite material according to claim 1, wherein: In step S101, the aluminum-germanium-tin alloy is smelted, the smelted alloy is gas-atomized, the temperature is cooled to room temperature after gas atomization, the alloy is etched with hydrochloric acid, and then washed with water to remove residual acid.

4. The method for preparing a MXene / Sn composite material according to claim 1, wherein: In S102, the surface treatment method of the porous tin is as follows: the porous tin prepared in S101 is heated in an air environment at a temperature of 150-250° C. for 5-10 minutes.

5. The method for preparing a MXene / Sn composite material according to claim 1, wherein: In S102, the surface treatment method of the porous tin is: the porous tin prepared in S101 is soaked in a mixed solution of sulfuric acid and hydrogen peroxide.

6. The method for preparing a MXene / Sn composite material according to claim 1, wherein: S201, MXene preparation method is: using lithium fluoride and hydrochloric acid to MAX phase (Ti3C2T X ) for etching, the etching time is 12~72h, the etching temperature is 25~40℃, the stirring rate is 100~800rpm, the solid-liquid ratio is 1g:10~20mL, and the MXene is washed and separated after etching.

7. The method for preparing a MXene / Sn composite material according to claim 1, wherein: In S201, the MXene is exfoliated layer by layer, and dimethyl sulfoxide (DMSO) or tetramethylammonium hydroxide (TMAOH) is used as an intercalation agent to assist ultrasonic exfoliation. The separated solution is centrifuged to remove the unexfoliated MXene multilayer particles.

8. The method for preparing a MXene / Sn composite material according to claim 1, wherein: S202, the method for MXene surface modification is as follows: slowly adding hydrogen peroxide to the MXene aqueous solution prepared in S201 and stirring the reaction; mixing APTES (γ-aminopropyltriethoxysilane) with water and stirring the hydrolysis; adding the MXene dispersion to the APTES hydrolyzate to react, and then centrifuging the dispersion and washing it multiple times to remove unreacted APTES.

9. The method for preparing a MXene / Sn composite material according to claim 1, wherein: S3, the method for composite of porous tin and MXene is as follows: the porous tin obtained by treatment with S102 is dispersed in water and ultrasonically dispersed; MXene is added thereto (according to the mass ratio of MXene:Sn=1:1.1~1.3); the two are mixed, the pH is adjusted to 3~4 and then stirred. After the stirring is completed, the unbound porous tin particles and the supernatant are removed by centrifugation, and finally the composite MXene / Sn composite material is obtained by freeze-drying.

10. A battery comprising a MXene / Sn composite material prepared by the method according to any one of claims 1 to 8.

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