A preparation method of a flexible film electrode based on a multi-valence state transition metal oxide modified MXene

Abstract

The application provides a preparation method of a flexible thin film electrode based on a multivalent transition metal oxide modified MXene, and comprises the following steps: S1, placing MAX raw materials into acid liquor for etching, and then performing intercalation treatment to obtain an MXene colloidal solution; S2, adding a transition metal oxide dispersion liquid into a reaction kettle to perform a hydrothermal reduction reaction to obtain a multivalent transition metal oxide colloidal solution; and S3, mixing the MXene colloidal solution and the multivalent transition metal oxide colloidal solution, stirring and reacting, and then forming a film to obtain a flexible thin film electrode. The flexible thin film electrode prepared by the application has good mechanical flexibility and electrochemical performance. The multivalent transition metal oxide is stably combined with the MXene, effectively alleviates the problem of the re-stacking of two-dimensional MXene nanosheets, increases the number of active sites, and further improves the electrochemical activity, and the comprehensive performance is excellent.

Description

Technical Field

[0001] This invention relates to the field of energy storage device technology, and specifically to a method for preparing a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides. Background Technology

[0002] With the increasing demand for flexible energy storage devices in portable electronic devices, flexible supercapacitors, as an energy storage device that combines high power density and mechanical flexibility, have gradually become a research hotspot in this field. Compared with traditional solid-state batteries, these devices not only possess rapid charge-discharge capabilities and stable cycle life, but their unique deformability also gives them significant advantages in emerging fields such as wearable electronics and implantable medical devices. As the core component of flexible supercapacitors, the material selection and structural design of the flexible electrode directly determine the overall performance of the device. Currently, researchers commonly use nanomaterials such as carbon nanotubes and graphene to construct flexible electrodes. By optimizing the microstructure of the materials, the specific surface area and ion transport efficiency of the electrodes can be effectively improved, thereby achieving higher energy storage density and superior rate performance.

[0003] As a revolutionary representative of two-dimensional layered materials, MXene exhibits unique material advantages through structural modulation of transition metal carbide / nitride units: its highly conductive network and controllable surface chemistry enable the material to combine the fabrication suitability of thin-film devices with a highly efficient charge storage mechanism dominated by pseudocapacitance. However, the tendency of MXene nanosheets to self-aggregate between layers leads to denser stacking, which not only prolongs the ion diffusion path but also reduces the number of active sites.

[0004] Against this backdrop, developing MXene functionalization techniques with microstructure control strategies has become a key issue in the field of materials engineering. Summary of the Invention

[0005] Based on this, the present invention provides a method for preparing a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides. The prepared flexible thin-film electrode exhibits excellent mechanical flexibility and electrochemical performance. The present invention effectively alleviates the problem of two-dimensional MXene nanosheet recombination by stably binding multivalent transition metal oxides with MXene, while simultaneously increasing the number of active sites, thereby enhancing its electrochemical activity and resulting in excellent overall performance.

[0006] One object of the present invention is to provide a method for fabricating a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides, the method comprising the following steps: S1. The MAX raw material is placed in an acid solution for etching, and then intercalation is performed to obtain an MXene colloidal solution; S2. The transition metal oxide dispersion is added to the reactor to carry out a hydrothermal reduction reaction to obtain multivalent transition metal oxides. A solvent is added to prepare a multivalent transition metal oxide colloidal solution. S3. The MXene colloidal solution is mixed with the multivalent transition metal oxide colloidal solution, and after stirring and reacting, a flexible thin film electrode based on multivalent transition metal oxide modified MXene is obtained; in, The transition metal is selected from at least one of V, Mn, Co or Mo; The chemical formula of the MAX raw material is MAX; The M is selected from at least one of Ti, V, Nb, Mo, Zr, Cr or Hf; The A is selected from at least one of Al, Ga, Si, Ti, Sn, or Ge; X is selected from at least one of C or N.

[0007] Furthermore, in step S1, the acid solution is a mixture of hydrochloric acid and hydrofluoric acid.

[0008] Furthermore, in step S1, lithium chloride is used as the intercalating agent for the intercalation.

[0009] Furthermore, in step S2, the hydrothermal reduction reaction is carried out at a temperature of 160°C for 24 hours.

[0010] Further, the transition metal is preferably vanadium, the transition metal oxide is preferably vanadium pentoxide, and the multivalent transition metal oxide is preferably V6O. 13 .

[0011] Furthermore, in step S3, the doping percentage of the MXene colloidal solution and the multivalent transition metal oxide colloidal solution is 5-200%.

[0012] Furthermore, the concentration of the MXene colloidal solution is 3-30 mg·mL. -1 .

[0013] Furthermore, in step S3, the temperature of the stirring reaction is 20-30°C, and the time is 4-48 h.

[0014] Another objective of this invention is to provide the application of the above-mentioned method for preparing flexible thin-film electrodes based on multivalent transition metal oxide-modified MXene in energy storage devices.

[0015] The present invention has the following beneficial effects: This invention prepares flexible thin-film electrodes by modifying MXene with multivalent transition metal oxides. First, the O in the multivalent transition metal oxide forms hydrogen bonds with the hydroxyl groups of MXene, achieving adhesion. The presence of multivalent transition metal ions effectively supplements the active sites of MXene, creating a synergistic effect and constructing abundant ion adsorption / deintercalation active sites. Second, the multivalent transition metal oxide itself possesses characteristics such as high capacity, fast ion transport, and good rate performance, effectively improving the electrochemical performance of the MXene composite material. This unique microstructure not only provides a reliable structural guarantee for achieving high specific capacitance and excellent cycle stability in supercapacitors but also significantly enhances the overall electrochemical performance of the composite material in supercapacitor devices. The technical solution proposed in this invention provides an innovative path for the interface synergistic optimization of MXene-based flexible supercapacitors, which is of great significance for promoting the practical application of wearable electronic energy storage technology. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the preparation method of the present invention.

[0017] Figure 2 The graphs show the electrochemical performance of the thin-film electrode prepared in Example 1 in a Swagelok battery. The left graph is the CV curve, and the right graph is the GCD curve.

[0018] Figure 3 The graphs show the electrochemical performance of the thin-film electrodes prepared in Examples 1-3 in Swagelok batteries. The left graph is the CV curve, and the right graph is the GCD curve.

[0019] Figure 4 The graphs show the electrochemical performance of the thin film electrodes prepared in Example 1 and Comparative Examples 1-2 in Swagelok batteries. The left graph is the CV curve, and the right graph is the GCD curve. Detailed Implementation

[0020] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0021] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0022] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​varying according to the desired performance to be obtained according to the invention.

[0023] Example 1 A method for fabricating a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides, the method comprising the following steps: S1. At room temperature, measure 1 mL HF, 2 mL deionized water and 7 mL HCl and add them to a polytetrafluoroethylene reaction vessel. Stir thoroughly for 5 min to mix evenly and obtain an acid solution. Weigh 0.5 g of excess aluminum-doped Ti3AlC2MAX phase (the molar ratio of each element in the MAX phase is Ti:C:Al = 2:1.25:2.2, and the Ti3AlC2MAX phase with excess Al is simply referred to as Al-Ti3AlC2, the same below) and add it to the acid solution. Etch at 400 r / min in a constant temperature water bath at 40℃ for 48 h with continuous stirring. After etching, the reaction product is centrifuged and washed multiple times until the supernatant is neutral. The lower precipitate is collected to obtain the multilayer Mxene. Dissolve 0.5 g of lithium chloride (LiCl) in 25 mL of deionized water, then add the multilayer MXene, and continue to stir magnetically at 400 r / min for 24 h. After centrifugation until the supernatant turns black and the lower precipitate expands significantly, perform ultrasonic dispersion for 30 min, followed by centrifugation at 1500 r / min for 20 min and 3500 r / min for 15 min, and collect the upper dispersion to obtain the MXene colloidal solution. The concentration was determined by vacuum filtration of 2 mL of the MXene colloidal solution followed by vacuum drying to obtain a release film. The concentration of the MXene colloidal solution obtained from 0.5 g Al-Ti3AlC2 raw material using the above process was measured to be 10 mg / mL. S2. 0.4 g of vanadium pentoxide (V₂O₅) was added to a mixture of ethanol and deionized water at a volume ratio of 5:4 (18 mL). The mixture was stirred continuously at 800 r / min for 2 h, then transferred to a 100 mL autoclave. After sealing, it was kept at 160 °C for 24 h. After cooling to room temperature, it was washed with ethanol and deionized water by centrifugation and dried under vacuum to obtain V₆O₅. 13The original product was then added to deionized water as a solvent, and the mixture was sonicated for 3 h to prepare a 5 mg / ml multivalent vanadium colloidal solution. S3. Add a 50% (by mass) multivalent vanadium colloidal solution (i.e., a 1:1 volume ratio of multivalent vanadium colloidal solution to MXene colloidal solution) to the MXene colloidal solution, mix and stir at room temperature for 24 h, and allow to cool naturally to room temperature to obtain MXene / V6O. 13 The composite dispersion was used to form a film by vacuum filtration (filter membrane pore size 0.22 μm), and then the film was placed in a vacuum drying oven at 30℃ for 4 h to finally obtain a flexible thin film electrode based on MXene modified with multivalent transition metal oxide.

[0024] Example 2 A method for fabricating a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides differs from Example 1 in that step S3 is modified as follows: S3. Add a 20% (w / w) polyvalent vanadium colloidal solution (i.e., a volume ratio of polyvalent vanadium colloidal solution to MXene colloidal solution of 2:5) to the MXene colloidal solution, mix and stir at room temperature for 24 h, and allow to cool naturally to room temperature to obtain MXene / V6O. 13 The composite dispersion was used to form a film by vacuum filtration (filter membrane pore size 0.22 μm), and then the film was placed in a vacuum drying oven at 30℃ for 4 h to finally obtain a flexible thin film electrode based on MXene modified with multivalent transition metal oxide.

[0025] Example 3 A method for fabricating a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides differs from Example 1 in that step S3 is modified as follows: S3. Add a 10% (w / w) polyvalent vanadium colloidal solution (i.e., a volume ratio of polyvalent vanadium colloidal solution to MXene colloidal solution of 1:5) to the MXene colloidal solution, mix and stir at room temperature for 24 h, and allow to cool naturally to room temperature to obtain MXene / V6O. 13 The composite dispersion was used to form a film by vacuum filtration (filter membrane pore size 0.22 μm), and then the film was placed in a vacuum drying oven at 30℃ for 4 h to finally obtain a flexible thin film electrode based on MXene modified with multivalent transition metal oxide.

[0026] Comparative Example 1 The difference between this comparative example and Example 1 is that step S2 is modified as follows: S2. The MXene colloidal solution was stirred at room temperature for 24 h and then naturally cooled to room temperature to obtain an MXene dispersion. The dispersion was then formed by vacuum filtration (filter membrane pore size 0.22 μm). The membrane was then placed in a vacuum drying oven at 30 °C for 4 h to obtain the final thin film electrode.

[0027] Comparative Example 2 The difference between this comparative example and Example 1 is that steps S2 and S3 are modified as follows: S2. Add V2O5 to deionized water to prepare a V2O5 dispersion of 5 mg / ml; S3. Add 10% of V2O5 dispersion (i.e., the volume ratio of V2O5 dispersion to MXene colloidal solution is 1:5) to MXene colloidal solution and mix and stir at room temperature for 24 h. After naturally cooling to room temperature, obtain MXene / V2O5 composite dispersion. Form a film by vacuum filtration (filter membrane pore size 0.22 μm). Then place the film in a vacuum drying oven at 30℃ for 4 h to finally obtain the thin film electrode.

[0028] Test case The thin film electrodes prepared in the examples and comparative examples were tested using methods that, unless otherwise specified, are conventional testing methods for those skilled in the art.

[0029] Figure 1 This is a schematic diagram of the preparation method of the present invention, which shows that the hydroxyl active group in ethanol plays a key role. The hydroxyl group, through strong reduction, converts V in V₂O₅... 5+ Restore to V 2+ With V 3+ Ions. In the preparation of MXene / V6O 13 In thin-film electrodes, MXene, as a two-dimensional layered material, possesses a high specific surface area and abundant surface functional groups (such as -OH, -O, etc.). When V6O 13 When combined with MXene, V6O 13 The oxygen atoms are bonded to the functional groups on the MXene surface via hydrogen bonds or covalent bonds. This interfacial interaction not only enables V6O 13 Uniform loading between MXene layers significantly enhances the interfacial bonding between the two phases. Furthermore, the two-dimensional layered structure of MXene provides high-speed channels for electron transport, while the embedded V6O... 13 By leveraging the advantages of nanostructures, the electronic conduction pathway of the composite system is further optimized, ultimately forming a composite thin-film electrode that combines flexibility and synergistic electrochemical performance.

[0030] Figure 2The graphs show the electrochemical performance of the thin-film electrode prepared in Example 1 in a Swagelok battery. The left graph is the CV curve, and the right graph is the GCD curve. A three-electrode system was constructed using the thin-film electrode prepared in Example 1 as the working electrode, activated carbon as the counter electrode, and Ag / AgCl as the reference electrode. CV and GCD tests were performed in 3M AlCl3 electrolyte. The specific capacitance results measured at 2-200 mV / s and 1-20 A / g are shown in Tables 1 and 2.

[0031] Table 1 Table 2 Figure 3 The graphs show the electrochemical performance of the thin-film electrodes prepared in Examples 1-3 in Swagelok batteries. The left graph is the CV curve, and the right graph is the GCD curve. Using the thin-film electrodes prepared in Examples 1-3 directly as the working electrode, activated carbon as the counter electrode, and Ag / AgCl as the reference electrode, a three-electrode system was constructed. CV and GCD tests were performed in 3M AlCl3 electrolyte. The specific capacitance results measured at 2 mV / s and 1 A / g are shown in Table 3. It can be seen that the electrochemical performance of the formulation in Example 1 is significantly higher than that in Examples 2 and 3.

[0032] Table 3 Figure 4 The graphs show the electrochemical performance of the thin-film electrodes prepared in Example 1 and Comparative Examples 1-2 in a Swagelok battery. The left graph is the CV curve, and the right graph is the GCD curve. Three-electrode systems were constructed using the thin-film electrodes prepared in Example 1 and Comparative Examples 1-2 as the working electrode, activated carbon as the counter electrode, and Ag / AgCl as the reference electrode. CV and GCD tests were performed in 3M AlCl3 electrolyte. The specific capacitance results measured at 2 mV / s and 1 A / g are shown in Table 4. It can be seen that the electrochemical performance of Example 1 is superior to that of Examples 1-2, which is due to the V6O in Example 1. 13 Its high energy storage capacity allows it to more effectively build energy storage networks between MXene layers.

[0033] Table 4 It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0034] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for fabricating a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides, characterized in that, The method for fabricating the flexible thin-film electrode based on MXene modified with multivalent transition metal oxides includes the following steps: S1. The MAX raw material is placed in an acid solution for etching, and then intercalation is performed to obtain an MXene colloidal solution; S2. The transition metal oxide dispersion is added to the reactor to carry out a hydrothermal reduction reaction to obtain multivalent transition metal oxides. A solvent is added to prepare a multivalent transition metal oxide colloidal solution. S3. The MXene colloidal solution is mixed with the multivalent transition metal oxide colloidal solution, and after stirring and reacting, a flexible thin film electrode based on multivalent transition metal oxide modified MXene is obtained; in, The transition metal is selected from at least one of V, Mn, Co or Mo; The chemical formula of the MAX raw material is MAX; The M is selected from at least one of Ti, V, Nb, Mo, Zr, Cr or Hf; The A is selected from at least one of Al, Ga, Si, Ti, Sn, or Ge; X is selected from at least one of C or N.

2. The method for fabricating a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides according to claim 1, characterized in that, In step S1, the acid solution is a mixture of hydrochloric acid and hydrofluoric acid.

3. The method for fabricating a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides according to claim 1, characterized in that, In step S1, lithium chloride is used as the intercalating agent for the intercalation.

4. The method for preparing a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides according to claim 1, characterized in that, In step S2, the hydrothermal reduction reaction is carried out at a temperature of 160°C for 24 hours.

5. The method for fabricating a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides according to claim 1, characterized in that, The transition metal is V.

6. The method for fabricating a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides according to claim 1, characterized in that, In step S3, the doping percentage of the MXene colloidal solution and the multivalent transition metal oxide colloidal solution is 5-200%.

7. The method for preparing a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides according to claim 6, characterized in that, The concentration of the MXene colloidal solution is 3-30 mg / mL. -1 .

8. The method for fabricating a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides according to claim 1, characterized in that, In step S3, the temperature of the stirring reaction is 20-30℃ and the time is 4-48 h.

9. The application of the method for preparing a flexible thin-film electrode based on MXene modified with multivalent transition metal oxides as described in any one of claims 1-8 in energy storage devices.

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