Titanium carbide electrode with hierarchical porous structure and preparation method and application thereof

Abstract

The application provides a titanium carbide electrode with a hierarchical porous structure and a preparation method and application thereof, relates to the technical field of electrochemical energy storage, and the preparation method of the titanium carbide electrode with the hierarchical porous structure comprises the following steps: titanium aluminum carbide powder is taken and added into a mixed solution containing LiF and HCl to react; the sedimentation is repeatedly centrifuged and washed with water, the sedimentation is taken and placed in water to be ultrasonically stripped, the upper colloidal layer is taken by centrifugation, Ti3C2T x dispersion is obtained; sulfuric acid solution is added into the Ti3C2T x dispersion to be oxidatively modified, a modified suspension is obtained, vacuum drying is carried out, vacuum suction filtration is carried out, and O-Ti3C2T x thin film loaded on a filter membrane is obtained; the O-Ti3C2T x thin film loaded on the filter membrane is vacuum dried, an aerogel / thin film with a hierarchical porous structure is obtained; the aerogel / thin film with the hierarchical porous structure is stripped from the filter membrane, and a titanium carbide electrode with a hierarchical porous structure is obtained.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage technology, and more specifically, to a titanium-carbon electrode with a hierarchical porous structure, its preparation method, and its application. Background Technology

[0002] With the rapid development of portable electronic devices and electric vehicles, higher demands are being placed on electrochemical energy storage devices. Supercapacitors are highly favored due to their high power density and long cycle life. Among numerous electrode materials, two-dimensional transition metal carbides / nitrides (MXenes), especially titanium aluminum carbide (Ti3C2T), are particularly popular. x Ti3C2T, with its metallic-grade high conductivity, hydrophilic surface, and abundant surface functional groups (such as -F, -O, -OH), shows great potential in the field of pseudocapacitive energy storage. However, in practical applications, Ti3C2T... x Nanosheets tend to exhibit severe self-stacking effects. This is due to the fact that Ti3C2T... x Strong van der Waals forces and hydrogen bonds exist between nanosheets, leading to irreversible recombination during filtration or drying to remove moisture. This results in a dense, layered structure in the prepared electrode material, resembling tightly stacked playing cards. This significantly reduces the effective specific surface area, trapping the abundant active sites between the layers and preventing contact with the electrolyte. This stacking phenomenon caused by van der Waals forces makes Ti3C2T... x The degeneration from "two-dimensional sheets" to "dense bulk" results in an elongated ion transport path, rendering many internal active sites unusable and severely limiting its rate performance and capacity. The dense stacked structure not only elongates the ion diffusion path, leading to slow transport kinetics, but also shields many internal active sites, preventing them from participating in reactions and limiting specific capacitance and rate performance. Summary of the Invention

[0003] This invention aims to solve the problem caused by Ti3C2T x The degradation from "two-dimensional layers" to "dense bulk" leads to problems that severely limit rate performance and capacity performance.

[0004] To address the above problems, this invention provides a titanium-carbon electrode with a hierarchical porous structure, its preparation method, and its application.

[0005] In a first aspect, the present invention provides a method for preparing a carbon titanate electrode with a hierarchical porous structure, comprising the following steps: S1: Add titanium aluminum carbide powder to a mixed solution containing LiF and HCl to selectively etch away the Al atomic layer; repeatedly centrifuge and wash the precipitate until the pH of the supernatant reaches above 6; place the precipitate in water for ultrasonic peeling; centrifuge to collect the upper colloid to obtain Ti3C2T.x Dispersion; S2: To Ti3C2T x Sulfuric acid solution was added to the dispersion for oxidative modification to obtain a modified suspension, which was then vacuum dried at 35 °C to 45 °C and vacuum filtered to obtain O-Ti3C2T loaded on a filter membrane. x film; S3: O-Ti3C2T loaded on the filter membrane x The film was vacuum dried at a cold trap temperature of -40 ℃ to -50 ℃ for more than 24 hours to obtain an aerogel / film with a hierarchical porous structure; S4: Peel the aerogel / film with a hierarchical porous structure from the filter membrane to obtain a carbon titanate electrode with a hierarchical porous structure.

[0006] Optionally, in S1, titanium aluminum carbide powder is added to a mixed solution containing LiF and HCl, and the mixture is stirred and reacted at 30 °C to 40 °C for more than 24 hours.

[0007] Optionally, in S2, the molar concentration of the sulfuric acid solution is from 2 mol / L to 4 mol / L.

[0008] Optionally, in S2, Ti3C2T x The volume ratio of the dispersion to the sulfuric acid solution is 0.5 to 2.

[0009] Optionally, in S2, the modified suspension is vacuum dried at 35 °C to 45 °C for more than 48 hours until a mixed dough state is obtained.

[0010] Optionally, in S2, O-Ti3C2T x The film contains uniformly distributed nanoscale in-plane mesopores with pore sizes ranging from 2 nm to 50 nm and additional interlayer micropore channels with pore sizes less than 2 nm.

[0011] Optionally, in S3, the vacuum degree of vacuum drying is 1 Pa to 2 Pa.

[0012] Optionally, in S3, the aerogel / film has macropores with a pore size greater than 50 nm inside.

[0013] Secondly, the present invention provides a titanium carbon electrode with a hierarchical porous structure, which is prepared by the method for preparing a titanium carbon electrode with a hierarchical porous structure as described in any of the preceding claims.

[0014] Thirdly, the present invention provides an application of the titanium carbon electrode with a hierarchical porous structure as described above in the field of self-supporting electrodes.

[0015] The beneficial effects of the titanium-carbon electrode with a hierarchical porous structure, its preparation method, and its application of the present invention are as follows: Adding titanium-aluminum carbide to a mixed solution containing LiF and HCl can selectively etch away the Al atomic layer, thereby obtaining a layered Ti3C2T electrode. x Nanosheets were used to precipitate and purify the reaction product through repeated centrifugation and washing until the pH of the supernatant reached above 6 to ensure the removal of residual acid and impurities. Subsequently, the precipitate was subjected to ultrasonic exfoliation in water to remove Ti3C2T nanosheets. x Nanosheets are separated and dispersed from their stacked state, and the upper colloidal Ti3C2T layer can be obtained by centrifugation. x Dispersion; Ti3C2T x The dispersion was oxidized by adding sulfuric acid solution to Ti3C2T. x Surface to H + It has extremely high adsorption energy; in an acidic environment, H + It rapidly adsorbs and protonates the surface, altering the surface's electronic environment and contributing to the formation of a porous structure; the protonated surface significantly enhances the resistance to SO4. 2- The adsorption affinity of SO4 makes it possible for SO4 to be adsorbed. 2- It can act as a transient species, uniformly anchored in Ti3C2T x On the base surface; anchored SO4 2- A localized micro-reaction zone was constructed, inducing a mild oxidation reaction in which a small number of Ti atoms were oxidized to soluble Ti. 4+ The Ti-O terminals are removed from the lattice, leaving them in situ, thus "etching" uniformly distributed nanoscale in-plane mesopores with diameters ranging from 2 nm to 50 nm within the sheet. Unlike the severe damage caused by strong oxidants such as nitric acid, this process is self-limiting and spatially uniform, preserving the two-dimensional conductive framework while avoiding excessive oxidation. Furthermore, SO42-... 2- As an intermediate medium to assist proton-mediated oxidation, the reaction does not form stable sulfur-containing functional groups, resulting in no sulfur residue in the final product. However, this oxidation process effectively expands the interlayer spacing, forming additional interlayer microporous channels with pore sizes less than 2 nm. When vacuum dried at a cold trap temperature of -40 °C to -50 °C for more than 24 hours, as the ice crystals sublimate, the sites originally occupied by the ice crystals form macroporous channels with pore sizes greater than 50 nm, while Ti3C2T... x Because micropores and mesopores are retained between the layers, an aerogel / film with a continuous hierarchical porous structure of "micropore-mesopore-macropore" is finally formed, which increases the effective specific surface area, reduces ion transport paths, and makes full use of internal active sites, thereby improving rate performance and capacity performance. Attached Figure Description

[0016] Figure 1This is a schematic flowchart of a method for preparing a carbon titanide electrode with a hierarchical porous structure according to an embodiment of the present invention. Figure 2 The original titanium aluminum carbide (Ti3C2T) of Example 1 x TEM image of the powder; Figure 3 This is a TEM image of the aerogel / film with a hierarchical porous structure from Example 1. Figure 4 The original Ti3C2T in step 1 of Example 1 x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x XRD patterns of the three samples; Figure 5 This is a SEM image of the original titanium aluminum carbide thin film from Example 1; Figure 6 This is a cross-sectional SEM image of the aerogel / film with a hierarchical porous structure in Example 1; Figure 7 The original Ti3C2T in step 1 of Example 1 x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x Comparison of nitrogen adsorption-desorption isotherms for the three samples; Figure 8 The original Ti3C2T in step 1 of Example 1 x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x A comparison chart of the porosity of the three samples; Figure 9 The original Ti3C2T in step 1 of Example 1 x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x Schematic diagram of pore size distribution curves for the three samples; Figure 10 The original Ti3C2T in step 1 of Example 1 x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x XPS spectra of the three samples; Figure 11 The original Ti3C2T in step 1 of Example 1 xPowder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x Comparison of GCD curves of the three samples at a current density of 1 A / g; Figure 12 The original Ti3C2T in step 1 of Example 1 x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x Comparison of GCD curves for the three samples at a current density increased to 20 A / g; Figure 13 The aerogel / film (IO-Ti3C2T) of Example 1 x GCD curves of the sample electrode at different current densities (1 A / g to 20 A / g); Figure 14 The original Ti3C2T in step 1 of Example 1 x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x Comparison of the specific capacitance of the three samples under different current densities; Figure 15 The left figure shows the original Ti3C2T in step 1 of Example 1. x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x A comparison chart of the magnification performance of the three samples calculated based on CV testing (different scan rates); Figure 15 The right figure shows the original Ti3C2T in step 1 of Example 1. x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x A comparison chart of the rate performance of the three samples calculated based on GCD testing (different current densities); Figure 16 The original Ti3C2T in step 1 of Example 1 x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x (3) Long-cycle stability test results of three samples at a current density of 10 A / g. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0018] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this invention's description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "comprising" and its variations as used herein are open-ended inclusion, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the description below.

[0019] This invention provides a titanium-carbon electrode with a hierarchical porous structure, its preparation method, and its application.

[0020] like Figure 1 As shown, an embodiment of the present invention provides a method for preparing a carbon titanate electrode with a hierarchical porous structure, comprising the following steps: S1: Add titanium aluminum carbide powder to a mixed solution containing LiF and HCl to selectively etch away the Al atomic layer; repeatedly centrifuge and wash the precipitate until the pH of the supernatant reaches above 6; place the precipitate in water for ultrasonic peeling; centrifuge to collect the upper colloid to obtain Ti3C2T. x Dispersion; S2: To Ti3C2T x Sulfuric acid solution was added to the dispersion for oxidative modification to obtain a modified suspension, which was then vacuum dried at 35 °C to 45 °C and vacuum filtered to obtain O-Ti3C2T loaded on a filter membrane. x film; S3: O-Ti3C2T loaded on the filter membrane x The film was vacuum dried at a cold trap temperature of -40 ℃ to -50 ℃ for more than 24 hours to obtain an aerogel / film with a hierarchical porous structure; S4: Peel the aerogel / film with a hierarchical porous structure from the filter membrane to obtain a carbon titanate electrode with a hierarchical porous structure.

[0021] Specifically, a hierarchical porous structure refers to a pore system within a material that simultaneously contains micropores (pore size less than 2 nanometers), mesopores (pore size between 2 and 50 nanometers), and macropores (pore size greater than 50 nanometers). This structure can provide abundant active sites and promote the rapid transport of electrolyte ions.

[0022] Titanium carbide electrodes refer to electrodes made primarily of titanium carbide (MXene), such as aluminum titanium carbide (Ti3C2T). x This electrode typically exhibits excellent conductivity and electrochemical energy storage performance.

[0023] Ti3C2T x Dispersions refer to the selective etching of MAX phase precursors (e.g., Ti3C2T). x After ultrasonic ablation, Ti3C2T x A colloidal solution in which nanosheets are uniformly dispersed in water or other solvents.

[0024] O-Ti3C2T x Thin film refers to Ti3C2T after being oxidized and modified with sulfuric acid solution. x Thin films formed from nanosheets. This oxidation modification process aims to introduce additional porous structures and surface functional groups.

[0025] Aerogels / films are solid materials with high porosity and low density formed by removing liquid components from gels or films through methods such as freeze-drying, while retaining their three-dimensional framework structure.

[0026] In the initial stage of the preparation process, titanium aluminum carbide powder is added to a mixed solution containing LiF and HCl. This mixed solution acts as an etchant, selectively removing the Al atomic layer from the titanium aluminum carbide to obtain layered Ti3C2T. x Nanosheets. The etching reaction can be carried out under different temperature conditions; for example, it can be carried out with stirring at room temperature or at a slightly elevated temperature to promote etching efficiency. After the reaction is complete, the reaction product is precipitated and purified by repeated centrifugation and washing until the pH of the supernatant reaches above 6 to ensure the removal of residual acid and impurities. Subsequently, the precipitate is subjected to ultrasonic exfoliation in water to remove Ti3C2T nanosheets. x The nanosheets were separated and dispersed from their stacked state. The upper colloid, Ti3C2T, could be obtained by centrifugation. x Dispersion.

[0027] After obtaining Ti3C2T xAfter dispersion, sulfuric acid solution is added for oxidative modification. The concentration of the sulfuric acid solution can be selected according to the desired degree of oxidation; for example, a lower or higher concentration of sulfuric acid solution can be used. Ti3C2T x The mixing ratio of the dispersion to the sulfuric acid solution can also be adjusted to control the intensity of the oxidation reaction and the morphology of the product. Through this oxidation modification process, Ti3C2T x The surface properties and interlayer structure of the nanosheets are altered, facilitating the formation of a porous structure. The resulting modified suspension is then vacuum-dried at 35 °C to 45 °C, with the drying time adjustable depending on the specific circumstances. The resulting dough-like substance is washed to remove the solvent, yielding a suspension. Next, the modified Ti3C2T is filtered under vacuum. x The material is collected and loaded onto a filter membrane to obtain O-Ti3C2T. x Thin film. During the formation process, a certain range of pore structures can be formed inside the thin film, for example, micropores or mesopores can be formed.

[0028] Next, immediately load the O-Ti3C2T onto the filter membrane. x The thin film is transferred to a cold trap environment at -40°C to -50°C for vacuum drying. This step typically employs freeze-drying technology, removing moisture from the film through ice crystal sublimation, effectively avoiding structural collapse caused by surface tension during conventional drying processes. The vacuum level during vacuum drying can be set according to equipment conditions; for example, a lower vacuum level can be used to promote the sublimation process. This drying process needs to continue for more than 24 hours to ensure that moisture is fully removed and that a stable three-dimensional framework structure forms inside the film. This yields an aerogel / film with a hierarchical porous structure. Channels of different sizes can be formed within this aerogel / film; for example, a macroporous structure can be formed.

[0029] Finally, the prepared aerogel / film with a hierarchical porous structure is carefully peeled off from the filter membrane on which it is loaded. The peeling operation can be performed using mechanical peeling or solvent-assisted peeling to ensure the integrity of the film structure. Through this peeling step, a carbon titanate electrode with a hierarchical porous structure is finally obtained.

[0030] This preparation method effectively inhibits the oxidation of Ti3C2T through the synergistic effect of selective etching, mild oxidation modification, and freeze-drying. xThe self-stacking of nanosheets successfully constructed a hierarchical porous structure with interconnected micropores, mesopores, and macropores. This allows for thorough wetting of the electrode material by the electrolyte, significantly shortening the ion transport path, accelerating transport kinetics, and effectively utilizing numerous internal active sites. This titanium-carbon electrode exhibits excellent specific capacitance, rate performance, and cycle stability in electrochemical energy storage applications.

[0031] In this embodiment, adding titanium aluminum carbide to a mixed solution containing LiF and HCl can selectively etch away the Al atomic layer, thereby obtaining layered Ti3C2T. x Nanosheets were used to precipitate and purify the reaction product through repeated centrifugation and washing until the pH of the supernatant reached above 6 to ensure the removal of residual acid and impurities. Subsequently, the precipitate was subjected to ultrasonic exfoliation in water to remove Ti3C2T nanosheets. x Nanosheets are separated and dispersed from their stacked state, and the upper colloidal Ti3C2T layer can be obtained by centrifugation. x Dispersion; Ti3C2T x The dispersion was oxidized by adding sulfuric acid solution to Ti3C2T. x Surface to H + It has extremely high adsorption energy; in an acidic environment, H + It rapidly adsorbs and protonates the surface, altering the surface's electronic environment and contributing to the formation of a porous structure; the protonated surface significantly enhances the resistance to SO4. 2- The adsorption affinity of SO4 makes it possible for SO4 to be adsorbed. 2- It can act as a transient species, uniformly anchored in Ti3C2T x On the base surface; anchored SO4 2- A localized micro-reaction zone was constructed, inducing a mild oxidation reaction in which a small number of Ti atoms were oxidized to soluble Ti. 4+ The Ti-O terminals are removed from the lattice, leaving them in situ, thus "etching" uniformly distributed nanoscale in-plane mesopores with diameters ranging from 2 nm to 50 nm within the sheet. Unlike the severe damage caused by strong oxidants such as nitric acid, this process is self-limiting and spatially uniform, preserving the two-dimensional conductive framework while avoiding excessive oxidation. Furthermore, SO42-... 2- As an intermediate medium to assist proton-mediated oxidation, it does not form stable sulfur-containing functional groups after the reaction, resulting in no sulfur residue in the final product. However, this oxidation process effectively expands the interlayer spacing, increasing additional interlayer microporous channels with pore sizes less than 2 nm. When vacuum dried at a cold trap temperature of -40 °C to -50 °C for more than 24 hours, as the ice crystals sublimate, the sites originally occupied by the ice crystals form macroporous channels with pore sizes greater than 50 nm, while Ti3C2T... xBecause micropores and mesopores are retained between the layers, an aerogel / film with a continuous hierarchical porous structure of "micropore-mesopore-macropore" is finally formed, which increases the effective specific surface area, reduces ion transport paths, and makes full use of internal active sites, thereby improving rate performance and capacity performance.

[0032] Optionally, in S1, titanium aluminum carbide powder is added to a mixed solution containing LiF and HCl, and the mixture is stirred and reacted at 30 °C to 40 °C for more than 24 hours.

[0033] Specifically, in step S1, when titanium aluminum carbide powder is added to a mixed solution containing LiF and HCl for the etching reaction, the reaction temperature is precisely controlled within the range of 30 °C to 40 °C. This temperature range is designed to balance the etching reaction rate with the Ti3C2T... x The stability of nanosheet structures. Lower temperatures may lead to low etching efficiency and excessively long reaction times; while excessively high temperatures may accelerate the etching process, but also increase the risk of corrosion of Ti3C2T. x The risk of excessive oxidation or structural damage to nanosheets can affect their intrinsic properties and the subsequent formation of porous structures. In practice, a constant-temperature water bath or oil bath can be used to heat the reaction vessel, and a temperature controller can be used to precisely maintain the temperature of the reaction system between 30 °C and 40 °C. Alternatively, a jacketed reactor with heating and cooling functions can be used, and the temperature of the circulating medium can be controlled to achieve precise regulation of the reaction temperature, ensuring the stable progress of the reaction process.

[0034] Simultaneously, continuous stirring is performed throughout the etching reaction. The purpose of stirring is to ensure sufficient contact between the titanium aluminum carbide powder and the LiF and HCl mixed solution, promoting uniform dispersion of the reactants, accelerating the etching process of the Al atomic layers, and preventing uneven etching caused by excessively high or low local concentrations. A magnetic stirrer can be used, rotating the magnetic pole in the reaction solution to provide gentle and continuous mixing. Alternatively, a mechanical stirrer can be used, providing stronger mixing through the rotation of the impeller, suitable for larger-scale reaction systems, ensuring the homogeneity of the reaction system.

[0035] Furthermore, the reaction time was set to be more than 24 hours. This sufficient reaction time was intended to ensure that the Al atomic layer could be fully and thoroughly etched away, thereby obtaining high-purity, highly crystalline Ti3C2T. xNanosheets. This helps overcome reaction kinetic limitations, ensuring complete etching and preventing residual Al atoms due to incomplete etching, which could affect the performance of the final electrode material. In practice, the removal of Al can be monitored by periodically sampling and performing X-ray diffraction (XRD) or energy-dispersive X-ray spectroscopy (EDS) analysis until no characteristic peaks of Al are detected or the content is below a set threshold, thus determining whether the reaction is complete. Alternatively, provided that the reaction temperature and stirring rate are kept constant, the reaction time can be extended to 36 or 48 hours based on experimental experience or pre-experiment results to further ensure thorough etching, especially when processing large batches of titanium aluminum carbide powder.

[0036] In this optional embodiment, in step S1, titanium aluminum carbide powder is added to a mixed solution containing LiF and HCl, and the reaction temperature is precisely controlled between 30°C and 40°C, while continuous stirring is performed, ensuring that the reaction time reaches at least 24 hours. This precise condition control can effectively avoid Ti3C2T corrosion caused by excessively high temperatures during the etching reaction. x Excessive oxidation or structural collapse of the nanosheets, as well as incomplete etching of the Al atomic layer due to excessively low temperature or insufficient reaction time, all contributed to the problem. Continuous stirring ensured the uniform distribution of reactants throughout the system, further improving etching efficiency and uniformity. Sufficient reaction time guaranteed the complete removal of the Al atomic layer, resulting in high-purity, highly dispersed, and structurally intact Ti3C2T. x Dispersion. This high-quality Ti3C2T x The dispersion provided an ideal starting material for the subsequent oxidation modification in step S2, ensuring the O-Ti3C2T x The film can form uniformly distributed nanoscale in-plane mesopores and interlayer micropore channels, which ultimately promotes the successful preparation of aerogel / film with hierarchical porous structure in step S3, thereby significantly improving the performance of the final carbon titanate electrode.

[0037] Optionally, in S2, the molar concentration of the sulfuric acid solution is from 2 mol / L to 4 mol / L.

[0038] Specifically, molar concentration is an indicator of the amount of solute (sulfuric acid) in a solution, directly affecting its chemical reactivity. Limiting the molar concentration of the sulfuric acid solution to the range of 2 mol / L to 4 mol / L aims to precisely control the reaction of Ti3C2T. x The degree of oxidation of the nanosheets. If the molar concentration is below 2 mol / L, the oxidation may be insufficient, leading to Ti3C2T... xInsufficient etching of the nanosheet surface makes it difficult to effectively form the desired mesoporous structure, thus failing to fully expose active sites or construct efficient ion transport channels. If the molar concentration exceeds 4 mol / L, the oxidation process may become too vigorous, leading to the degradation of Ti3C2T. x Excessive damage to the nanosheet structure can even cause the collapse or breakage of the layered structure, thereby disrupting the conductive framework of the material and affecting the overall performance and stability of the electrode. Therefore, the setting of this concentration range is based on a balance between oxidation etching kinetics and material structural integrity, ensuring that Ti3C2T is preserved to the maximum extent while effectively constructing a hierarchical porous structure. x Intrinsic properties of materials.

[0039] In this optional embodiment, by precisely controlling the molar concentration of the sulfuric acid solution within the range of 2 mol / L to 4 mol / L, this application can achieve the processing of Ti3C2T. x The oxidation modification of nanosheets is mild and controllable. In step S2, this specific concentration of sulfuric acid solution can moderately etch Ti3C2T. x Nanosheets, with uniformly distributed intraplane mesopores ranging from 2 nm to 50 nm in diameter and additional interlayer micropores smaller than 2 nm, form within them, while avoiding structural damage caused by excessive oxidation. This precise concentration control ensures both the effectiveness of the oxidation modification process and the integrity of the material structure, thus laying the foundation for subsequent steps to construct aerogels / films with hierarchical porous structures. Compared to sulfuric acid solutions with excessively high or low concentrations, this concentration range can more effectively suppress Ti3C2T x The self-stacking effect of nanosheets increases the effective specific surface area of ​​the material and constructs a continuous and interconnected ion transport network, thereby significantly improving the ion transport kinetics and active site utilization of the electrode material, ultimately helping to improve the specific capacitance and rate performance of the electrode.

[0040] Optionally, in S2, Ti3C2T x The volume ratio of the dispersion to the sulfuric acid solution is 0.5 to 2.

[0041] Specifically, this volume ratio is set to precisely control the ratio of oxidant to Ti3C2T. x The contact efficiency and reaction intensity of the material. For example, when the volume ratio is set in the lower range of 0.5 to 1, relatively mild oxidation modification can be achieved, which helps to maintain Ti3C2T xWhile maintaining the integrity of the layered structure, pore formation is gradually induced. On the other hand, setting the volume ratio in the higher range of 1 to 2 can promote a more significant oxidation effect, aiming to form the desired pore structure in a shorter time, while still ensuring the controllability of the reaction to avoid irreversible damage to the material's conductive framework. Precise control of this volume ratio can effectively guide the formation of nanoscale in-plane mesopores and interlayer micropores, laying the foundation for constructing a hierarchical porous structure in subsequent steps.

[0042] In this optional embodiment, by limiting Ti3C2T x The volume ratio of the dispersion to the sulfuric acid solution is 0.5 to 2. This ratio ensures reasonable control of the reactant concentration during the oxidation modification process, avoiding either excessive or insufficient oxidation reaction due to imbalance, thereby protecting the material structure from damage and promoting the formation of uniform channels. Specifically, a volume ratio in the range of 0.5 to 2 allows the sulfuric acid solution to react with Ti3C2T at a suitable concentration. x The uniform mixing of the dispersion and the gentle oxidation process prevent excessive oxidation caused by localized high concentrations, which could lead to sheet breakage, while ensuring a sufficient oxidation reaction to effectively create micropores and mesopores on the sheets, thus maintaining the integrity of the overall conductive network. This effectively solves the problem of uneven oxidation or over-oxidation caused by improper volume ratios, thereby avoiding damage to the material's conductive framework and achieving a uniform pore distribution. This provides a crucial guarantee for obtaining a titanium-carbon electrode with excellent electrochemical performance.

[0043] Optionally, in S2, the modified suspension is vacuum dried at 35 °C to 45 °C for more than 48 hours until a mixed dough state is obtained.

[0044] Specifically, the modified suspension is dried in a vacuum environment, with the drying temperature precisely controlled within the range of 35°C to 45°C. Vacuum drying lowers the boiling point of water, thereby achieving effective solvent removal at a relatively low temperature and avoiding damage to Ti3C2T at high temperatures. x The nanosheet structure causes damage. This temperature range is designed to provide a mild yet efficient drying environment that promotes solvent evaporation while maximally protecting the intrinsic structure of the material. For example, a vacuum oven with temperature control can be used, precisely maintaining the temperature between 35°C and 45°C by setting the heating plate or chamber temperature, while continuously evacuating the vacuum using a vacuum pump; alternatively, a vacuum drying device can be used, initially maintaining the heating plate temperature between 35°C and 45°C, combined with vacuum evacuation, to achieve mild drying of the modified suspension.

[0045] Meanwhile, the vacuum drying time was set to over 48 hours to ensure that the solvent in the modified suspension could evaporate fully and slowly. This long drying process helps to avoid excessive capillary forces between nanosheets due to rapid water loss, thereby effectively suppressing the formation of Ti3C2T. x The irreversible self-stacking phenomenon of nanosheets lays the foundation for the subsequent formation of materials with hierarchical porous structures. For example, the operating time of the vacuum drying equipment can be set to operate continuously for at least 48 hours, and the degree of drying can be confirmed by monitoring the material state or weight changes in real time; or, a staged drying strategy can be adopted, with a longer period of gentle vacuum drying (e.g., 48 hours) in the initial stage, and then the drying time can be appropriately extended according to the actual drying situation of the material until the target state is reached.

[0046] Finally, the drying process continues until the modified suspension reaches a dough-like state. This dough-like state refers to the modified suspension gradually losing most of its solvent during drying, forming a semi-solid homogeneous body with a certain degree of viscosity and plasticity. This state is a crucial precursor for subsequent vacuum filtration, indicating that the nanosheets within the material have initially formed a stable network structure while retaining a certain degree of flexibility, facilitating shaping without damaging its porous structure. For example, this can be determined visually and by touch; when the modified suspension transforms from a liquid or thin paste into a uniform, viscous, and plastic mass, it is considered to have reached the dough-like state. Alternatively, combined with weight loss monitoring, when the weight loss rate of the material reaches a preset value (e.g., solvent removal rate exceeds 90%) and the material exhibits semi-solid characteristics, it can be identified as being in the dough-like state.

[0047] In this optional embodiment, the temperature, time, and target state of the drying process are precisely defined to ensure that the modified suspension transforms into a specific physical form under controlled conditions, thereby optimizing the material structure and reducing defects. Specifically, in step S2, the modified suspension is vacuum dried at a temperature set between 35°C and 45°C to avoid excessively high temperatures causing oxidation reactions that damage the conductive framework or excessively low temperatures leading to insufficient drying; the drying time is at least 48 hours to provide a sufficient slow evaporation period and prevent nanosheet stacking and structural collapse caused by rapid moisture removal; finally, a mixed dough state is reached, indicating that the material forms a semi-solid homogeneous body, facilitating subsequent filtration operations and maintaining the integrity of the porous channels. This helps suppress self-stacking effects, promotes hierarchical connectivity of micropores, mesopores, and macropores, improves ion transport kinetics and accessibility of active sites, thereby significantly improving the ion transport efficiency and active site utilization of the electrode, ultimately achieving higher specific capacitance and rate performance.

[0048] Optionally, in S2, O-Ti3C2T xThe film contains uniformly distributed nanoscale in-plane mesopores with pore sizes ranging from 2 nm to 50 nm and additional interlayer micropore channels with pore sizes less than 2 nm.

[0049] Specifically, O-Ti3C2T x The film contains uniformly distributed nanoscale in-plane mesopores with pore sizes ranging from 2 nm to 50 nm, referring to the presence of these pores within the O-Ti3C2T film. x Within the two-dimensional sheet structure of the thin film, pores with diameters ranging from 2 to 50 nanometers are formed through methods such as oxidation etching. These pores are not located between layers but rather within the MXene sheets themselves. The presence of mesopores significantly increases the specific surface area of ​​the material, providing more adsorption sites and more direct transport pathways for electrolyte ions. The uniform distribution ensures efficient ion transport and full utilization of active sites throughout the electrode material, avoiding ion congestion or idle active sites in localized areas. One approach to this is through precise control of the sulfuric acid solution concentration, reaction temperature, and reaction time in step S2, enabling gentle and uniform oxidation etching on Ti3C2T. x Mesopores are formed on the surface of the lamellar sheets while avoiding damage to the lamellar framework. Another approach is to introduce specific surfactants or template agents during the oxidation modification process, which, through their action on Ti3C2T... x The adsorption and self-assembly behavior of the sheet surface guides the oxidation etching process, thereby forming nanoscale mesopores with uniform size and distribution.

[0050] Furthermore, the additional interlayer microporous channels with a pore size of less than 2 nm refer to those in O-Ti3C2T x In the layered structure of the thin film, extremely fine channels with pore sizes less than 2 nanometers are formed between adjacent MXene sheets. These microporous channels are naturally formed during the oxidation modification of MXene materials by controlling the interlayer spacing. The presence of microporous channels further increases the effective specific surface area of ​​the material, especially providing additional adsorption space and fast transport pathways for small-sized electrolyte ions. They can effectively promote the full wetting of the electrode material by the electrolyte and provide more electrochemical active sites, thereby improving the capacity and rate performance of the electrode. One way to achieve this is by precisely controlling the Ti3C2T in the S2 step. x The volume ratio of the dispersion to the sulfuric acid solution, and the subsequent vacuum drying conditions, resulted in O-Ti3C2T x When the layers form a thin film, they can maintain a certain interlayer spacing and form tiny, interconnected microporous channels. Another way to achieve this is by introducing substances that can interact with Ti3C2T during the oxidation modification process. xMolecules with weak interactions of surface functional groups form "spacers" between layers, thereby creating stable interlayer microporous channels with pore sizes less than 2 nm during the drying process.

[0051] In this optional embodiment, O-Ti3C2T x The specific pore structure design within the thin film effectively solves the problem of constructing effective hierarchical channels during oxidation modification. Uniformly distributed nanoscale in-plane mesopores ensure the continuity and uniformity of the channels, significantly reducing the tendency for nanosheets to self-stack and promoting rapid ion transport within the mesopores. Simultaneously, additional interlayer micropore channels with pore sizes less than 2 nm provide more microporous structures, greatly increasing the specific surface area and the number of active sites, thereby optimizing the electrolyte wetting effect and ion diffusion pathways. Overall, this synergistic effect of micropores and mesopores not only effectively inhibits the oxidation of Ti3C2T... x The irreversible stacking of nanosheets also creates a continuous and interconnected ion transport network, which allows the electrolyte to more fully wet the electrode material and ions to be transported more quickly inside the electrode, thereby significantly improving the capacitance and rate performance of the electrode.

[0052] Optionally, in S3, the vacuum degree of vacuum drying is 1 Pa to 2 Pa.

[0053] Specifically, vacuum drying, as a gentle dehydration technique, evaporates moisture at a lower temperature by reducing ambient pressure, thus avoiding potential damage to the material structure from high temperatures. Furthermore, precisely controlling the vacuum level within the range of 1 Pa to 2 Pa is crucial for O-Ti3C2T. x The drying process of the thin film is crucial. Specifically, the setting of this vacuum range aims to finely control the evaporation rate of the solvent (water). If the vacuum is too high (i.e., the pressure is much lower than 1 Pa), the solvent evaporation is too rapid, which may generate excessive capillary forces inside the film, leading to structural collapse, cracking, or pore deformation, thus damaging the integrity of its hierarchical porous structure. Conversely, if the vacuum is too low (i.e., the pressure is much higher than 2 Pa), the drying efficiency is low, which may result in residual moisture, affecting the final structural uniformity and stability of the aerogel / film. To achieve and maintain this precise vacuum level, various methods can be used. For example, a vacuum pump set equipped with a high-precision pressure sensor and feedback control system can be used to ensure that the vacuum level is stable within the target range by monitoring and adjusting the pump speed or valve opening in real time; or a multi-stage vacuum system can be used, first rapidly pumping to a certain pressure with a coarse vacuum pump, and then switching to a fine vacuum pump (such as a molecular pump or diffusion pump) for precise control to achieve a vacuum level of 1 Pa to 2 Pa.

[0054] In this optional embodiment, precisely controlling the vacuum level during vacuum drying in step S3 within the range of 1 Pa to 2 Pa effectively solves the problems of uneven drying, structural collapse, or pore damage caused by improper vacuum levels. This specific vacuum range ensures the drying quality of O-Ti3C2T. x The solvent evaporation rate during the aerogel / film formation process is optimal, avoiding damage to the fragile porous structure caused by strong capillary forces from rapid evaporation while ensuring thorough and uniform drying, preventing residual moisture from adversely affecting pore formation and stability. This allows the resulting aerogel / film with a hierarchical porous structure to perfectly retain its internal nanoscale in-plane mesopores, interlayer micropores, and macropores, ensuring the continuity and interconnectivity of these hierarchical channels. Therefore, this technical solution significantly improves the structural integrity and stability of the material, providing a solid foundation for its subsequent application as a carbon titanate electrode, facilitating sufficient electrolyte wetting and rapid ion transport, thereby optimizing the electrode's electrochemical performance.

[0055] Optionally, in S3, the aerogel / film has macropores with a pore size greater than 50 nm inside.

[0056] Specifically, "macropores with a pore size greater than 50 nm" refers to pore structures with a pore size typically greater than 50 nm. In electrode materials, these macropores primarily serve as "highways" for rapid electrolyte penetration and long-distance ion transport, significantly reducing the diffusion resistance of the electrolyte within the electrode and ensuring that the electrolyte can quickly and fully wet the deep regions of the electrode material. During the vacuum drying process in step S3, the methods for achieving macropores with a pore size greater than 50 nm can include, but are not limited to, the following two: One approach involves precisely controlling the cold trap temperature, vacuum level, and drying rate to regulate the ice crystal growth behavior of the solvent (water) before sublimation. For example, using a slower freezing rate or a specific temperature gradient can promote the formation of larger ice crystals. When these ice crystals sublimate under vacuum conditions, they will form ice crystals in the O-Ti3C2T region. x Large pores corresponding to the size of ice crystals are left inside the film.

[0057] Another implementation method is to pre-adjust the Ti3C2T x The concentration of the dispersion or the filtration conditions affect the O-Ti3C2T loaded on the filter membrane. x The thin film exhibits a certain degree of macroscopic inhomogeneity or relatively large initial voids during its formation. During the subsequent vacuum drying process, these initial large voids are retained and further developed during solvent sublimation, thereby forming macroporous channels with pore sizes greater than 50 nm.

[0058] In this optional embodiment, step S3 ensures the formation of macroporous channels with a pore size greater than 50 nm within the aerogel / film. These macroporous channels serve as macroscopic pathways for rapid electrolyte penetration and ion transport, effectively addressing the problems of insufficient electrolyte wetting and limited ion transport. Combining the nanoscale in-plane mesopores and interlayer micropores formed in step S2, this application constructs a continuously interconnected hierarchical porous structure of "micropore-mesopore-macropore". This structure not only provides abundant active sites, but more importantly, the macroporous channels can significantly shorten the diffusion path of ions within the electrode, accelerating electrolyte penetration and ion transport rates. This ensures that even under high-speed charge-discharge conditions, the electrolyte can fully contact all active sites, greatly improving the specific capacitance and rate performance of the electrode material, and effectively suppressing Ti3C2T x The self-stabilization of nanosheets maintains the stability of the material structure.

[0059] Another embodiment of the present invention provides a titanium carbon electrode with a hierarchical porous structure, which is prepared by the method for preparing a titanium carbon electrode with a hierarchical porous structure as described in any of the preceding claims.

[0060] Specifically, this preparation method aims to precisely control the microstructure of the electrode material, ensuring that it possesses a stable and continuous hierarchical porous structure during formation. By strictly controlling various parameters in the preparation process, such as reaction temperature, time, solution concentration, and drying conditions, the morphology and pore size distribution of the material can be precisely controlled. For example, by precisely controlling the etching process, the selective removal of the Al atomic layer is ensured, while avoiding the etching of Ti3C2T. x The method involves disrupting the nanosheet structure; by optimizing oxidation modification conditions, nanoscale in-plane mesopores and interlayer micropore channels are introduced within the nanosheets; then, a specific vacuum drying process is used to form an aerogel / film structure with macroporous channels. Furthermore, this method can also employ a multi-step synergistic preparation strategy, organically combining different structure-building mechanisms. For example, two-dimensional nanosheets can first be obtained through chemical etching, then micropores and mesopores can be introduced through surface modification, and finally, macroporous structures can be constructed through self-assembly or template methods. The synergistic effect of the entire process ensures the continuity and interconnectivity of hierarchical channels, and endows the electrode material with excellent mechanical stability and electrochemical performance.

[0061] In this embodiment, the obtained titanium carbon electrode can effectively suppress Ti3C2T x The irreversible self-stacking of nanosheets during fabrication avoids problems such as a significant reduction in effective specific surface area, insufficient electrolyte wetting, and limited ion transport. Specifically, this method selectively removes the Al atomic layer through the S1 step to obtain high-quality Ti3C2T. x Dispersion; subsequently, in step S2, by introducing Ti3C2T xThe dispersion was oxidized by adding sulfuric acid solution, and then vacuum dried at 35 °C to 45 °C. Vacuum filtration was then performed to obtain O-Ti3C2T loaded on a filter membrane. x A thin film is produced, containing uniformly distributed nanoscale in-plane mesopores with pore sizes ranging from 2 nm to 50 nm and additional interlayer micropore channels with pore sizes less than 2 nm. This modification process effectively increases the internal porosity and active sites of the material. Furthermore, in step S3, the O-Ti3C2T loaded onto the filter membrane... x The film was vacuum dried at a cold trap temperature of -40 ℃ to -50 ℃ for more than 24 hours to obtain an aerogel / film with a hierarchical porous structure containing macropores larger than 50 nm. This unique low-temperature vacuum drying process can maximize the preservation and construction of a continuous and interconnected "micropore-mesopore-macropore" hierarchical pore structure, effectively preventing the collapse of the pore structure during the drying process. Finally, in step S4, the aerogel / film with the hierarchical porous structure is peeled off from the filter membrane. The resulting titanium carbon electrode has a stable structure and continuous pores, avoiding the problems of pore damage or performance degradation after peeling. By constructing this interconnected hierarchical pore structure, the electrolyte can quickly and fully wet the electrode material, the ion transport path is significantly shortened, the transport kinetics are accelerated, and a large number of internal active sites can be fully utilized, thereby significantly improving the electrode's specific capacitance, rate performance, and cycle stability.

[0062] Another embodiment of the present invention provides the application of a titanium carbon electrode with a hierarchical porous structure as described above in the field of self-supporting electrodes.

[0063] Specifically, the core technical features involved in this application include "titanium carbon electrode with a hierarchical porous structure" and "application in the field of self-supporting electrodes." Among them, the "titanium carbon electrode with a hierarchical porous structure" refers to a type of electrode made of titanium carbon (Ti3C2T). x Electrodes using Ti3C2T as the main material and possessing a multi-level porous structure including micropores, mesopores, and macropores. This hierarchical porous structure is crucial for solving the problems of Ti3C2T. x Overcoming the challenges of self-stacking, limited ion transport, and low utilization of active sites in nanosheets is crucial, as they can provide high specific surface area, efficient electrolyte wetting channels, and rapid ion diffusion pathways. For example, by precisely controlling etching conditions and subsequent drying processes, such as supercritical drying or freeze-drying combined with heat treatment, a hierarchical network of channels with specific pore size distribution and connectivity can be formed. Furthermore, by introducing controllable sacrificial templates, such as polymer microspheres or carbon nanotubes, macroporous structures can be constructed between MXene sheets, while micropores and mesopores are formed through the MXene's own exfoliation process.

[0064] "Applications in the field of self-supporting electrodes" refers to the ability of this electrode material to function independently as an electrode without relying on additional current collectors or binders, bearing its own weight and resisting external stresses while maintaining structural integrity. This self-supporting characteristic is significant for simplifying electrode manufacturing processes and improving energy and power densities. One way to achieve self-supporting electrodes is by optimizing the macroscopic morphology and internal structure of the electrode, for example, by fabricating it into a flexible thin film or aerogel mass with sufficient mechanical strength, in which a tight and stable interconnect network is formed between MXene sheets. Another approach is to utilize the excellent flexibility and conductivity of MXene material itself, and through precise assembly techniques, such as directional cryogenics or casting, to construct self-supporting electrodes with anisotropic structures and high mechanical strength.

[0065] In this embodiment, a titanium carbon electrode with a hierarchical porous structure is applied to the field of self-supporting electrodes, effectively solving the problems of insufficient mechanical strength and easy collapse and deformation commonly found in traditional porous electrodes in self-supporting applications. Specifically, this titanium carbon electrode with a hierarchical porous structure has a continuous interconnected network of micropores, mesopores, and macropores inside. This not only ensures sufficient wetting of the electrolyte and rapid ion transport, but more importantly, these pore structures, especially the macropore channels and the overall aerogel / film structure, together construct a robust framework, giving the electrode excellent mechanical strength and structural stability. This allows the electrode to maintain its structural integrity without external support, effectively avoiding structural collapse or deformation caused by mechanical stress in practical applications. At the same time, since no additional binder or current collector is needed, this self-supporting electrode can retain Ti3C2T to the maximum extent. x The material's inherent high conductivity and abundant electrochemical active sites significantly improve the energy density, power density, and cycle stability of the electrode while ensuring mechanical stability, providing a new approach for the development of high-performance electrochemical energy storage devices.

[0066] The present invention will be further described below with reference to specific embodiments.

[0067] Example 1: Preparation of a carbon titanate electrode with a hierarchical porous structure.

[0068] 1. Take an appropriate amount of titanium aluminum carbide (Ti3C2T) x Powder, titanium aluminum carbide (Ti3C2T) powder, imaged using transmission electron microscopy. x ) powder, to obtain TEM images, such as Figure 2 As shown, titanium aluminum carbide (Ti3C2T) is visible. x The nanosheets have a smooth and even surface morphology with no obvious porous structure, resembling the original Ti3C2T. x Cross-sectional scanning electron microscope (SEM) image of the thin film, as shown. Figure 5As shown, the nanosheets exhibit close stacking, a dense interlayer structure, and tortuous, narrow ion transport channels. These nanosheets were then added to a pre-prepared mixed solution containing LiF and HCl. The LiF concentration in this mixed solution was 6 mol / L, and the HCl concentration was 9 mol / L. The mixture was placed in a constant-temperature water bath at 35 °C and stirred continuously for 24 hours. During this process, LiF and HCl synergistically etched and removed the Al atomic layer from titanium aluminum carbide, thereby exfoliating to obtain Ti3C2T. x Nanosheets. After the reaction, the resulting product was repeatedly centrifuged and washed with water until the pH of the supernatant reached 6. Subsequently, the precipitate was placed in deionized water and subjected to ultrasonic exfoliation to further disperse Ti3C2T. x Nanosheets. Finally, by centrifugation, the upper dark green colloid was collected to obtain a uniform monolayer or few-layer Ti3C2T. x Dispersion. This step, through a gentle etching and exfoliation process, effectively avoids excessive stacking of nanosheets in the initial stage, laying the foundation for subsequent construction of porous structures.

[0069] 2. To the Ti3C2T prepared above x Oxidative modification was performed by adding sulfuric acid solution to the dispersion. In this example, the molar concentration of the sulfuric acid solution was set to 3 mol / L. Ti3C2T x The volume ratio of dispersion to sulfuric acid solution was controlled at 1:1. The mixture was thoroughly stirred to form a modified suspension. Subsequently, the modified suspension was placed in a vacuum drying oven at 40 °C for 48 hours until the suspension transformed into a dough-like state. This drying process was carried out under mild conditions, avoiding structural damage that could be caused by traditional strong oxidants. The oxidation of Ti3C2T by sulfuric acid... x Oxygen-containing functional groups were introduced onto the surface of the nanosheets, inducing the formation of uniformly distributed nanoscale in-plane mesopores with pore sizes ranging from 2 nm to 50 nm and additional interlayer micropore channels with pore sizes less than 2 nm. The formation of these micropores and mesopores significantly increased the specific surface area of ​​the material and provided initial channels for the transport of electrolyte ions. After drying, the resulting dough was washed and vacuum filtered to obtain O-Ti3C2T loaded onto a filter membrane. x film.

[0070] 3. Loading O-Ti3C2T onto the filter membrane xThe thin film was transferred to a vacuum freeze dryer at a cold trap temperature of -45 °C for vacuum drying. The vacuum level was controlled at 2 Pa, and the drying time lasted for 24 hours. This freeze-drying process removes moisture through ice crystal sublimation, effectively avoiding the collapse and stacking of nanosheets caused by liquid-gas interfacial tension during traditional thermal drying. During ice crystal growth and sublimation, macroporous channels with a pore size greater than 50 nm were formed throughout the entire thin film. These macroporous channels are interconnected with the micropores and mesopores formed in step 2, jointly constructing a continuously interconnected hierarchical porous structure of "micropore-mesopore-macropore". This structure not only provides abundant active sites but also significantly shortens the ion transport path, overcoming the problem of limited ion transport in existing technologies.

[0071] 4. Carefully peel the aerogel / film with the hierarchical porous structure from the filter membrane to obtain the titanium carbon electrode with the hierarchical porous structure. Transmission electron microscopy (TEM) is used to image the aerogel / film with the hierarchical porous structure, as shown below. Figure 3 As shown, Figure 3 The area circled in the middle clearly shows that uniformly distributed in-plane mesopores are formed on the surface of the aerogel / film; cross-sectional SEM image of the aerogel / film, as shown. Figure 6 As shown, the film exhibits a loose porous structure with clearly defined vertically penetrating macropores. This electrode material possesses a highly interconnected hierarchical porous network, effectively suppressing the growth of Ti3C2T. x The self-stacking of nanosheets ensures thorough electrolyte wetting and provides rapid ion transport channels. Compared to existing methods that involve inserting spacers or vigorous oxidative etching, this method combines mild oxidative modification with freeze-drying to preserve Ti3C2T. x While maintaining intrinsic high conductivity, a stable hierarchical porous structure was successfully constructed, avoiding damage to the conductive framework and structural collapse, thereby significantly improving the specific capacitance, rate performance and cycle stability of the electrode material.

[0072] The original Ti3C2T from step 1 x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x X-ray diffraction (XRD) patterns of the three samples, as follows: Figure 4 As shown, the (002) diffraction peak shifts to a smaller angle, indicating an increase in interlayer spacing. Furthermore, the absence of characteristic peaks for oxides such as TiO2 in the spectrum confirms the mildness of the oxidation process. In step 1, the original Ti3C2T... x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) xComparison of nitrogen adsorption-desorption isotherms for the three samples, as shown in the figure. Figure 7 As shown, the specific surface area of ​​the material increases significantly after oxidation and freezing treatment. In step 1, the original Ti3C2T... x Thin films and frozen aerogels / films (IO-Ti3C2T) x A comparison of the porosity of the two samples is shown in the figure below. Figure 8 As shown, the data shows that IO-Ti3C2T x The porosity of the sample was significantly improved compared to the original sample. In step 1, the original Ti3C2T... x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x The pore size distribution curves (DFT model) of the three samples are shown below. Figure 9 As shown, the aerogel / film (IO-Ti3C2T) is displayed. x The sample simultaneously exhibits micropores, mesopores, and macropores, confirming the successful construction of a multi-scale hierarchical pore structure. The original Ti3C2T sample in step 1... x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x The X-ray photoelectron spectroscopy (XPS) high-resolution spectra of the three samples are shown below. Figure 10 As shown in the figure, the fitting analysis indicates that the content of -O functional groups (active sites) in the modified sample is significantly increased, which is beneficial to providing more pseudocapacitive active sites to promote electrochemical reactions.

[0073] In step 1, the original Ti3C2T x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x A comparison of the galvanostatic charge-discharge (GCD) curves of the three samples at a current density of 1 A / g is shown in the figure. Figure 11 As shown in the figure, the IO-Ti3C2T x The sample exhibited the longest charge-discharge time, and the curves displayed good symmetry and typical capacitive behavior, indicating that it possessed the highest specific capacitance. In step 1, the original Ti3C2T... x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x The GCD curves of the three samples are compared when the current density is increased to 20 A / g, as shown in the figure. Figure 12 As shown, the results indicate that even at high current densities, IO-Ti3C2T xIt maintained the longest discharge time without significant voltage drop, demonstrating its excellent charge storage capacity even under high current. Frozen aerogel / film (IO-Ti3C2T) x The GCD curves of the sample electrode at different current densities (1 A / g to 20 A / g) are shown below. Figure 13 As shown, it exhibits a stable charge-discharge waveform that remains stable even with increasing current density. The original Ti3C2T in step 1... x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x The comparison graph of the specific capacitance of the three samples under different current densities is shown below. Figure 14 As shown in the figure, the data clearly demonstrates that the IO-Ti3C2T x It exhibited the highest specific capacitance value throughout the entire testing range, and the most gradual degradation trend. The original Ti3C2T in Step 1... x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x The following is a comparison of the rate performance of three samples, calculated based on cyclic voltammetry (CV) testing (left figure, different scan rates) and GCD testing (right figure, different current densities), as shown in the figure. Figure 15 As shown in the comparison results, under a high current density of 20 A / g, the original Ti3C2T x The capacitance retention rate is only 3.9%, while the IO-Ti3C2T of this invention... x The retention rate reached as high as 51.6%, significantly improving the high-rate performance of the material. In step 1, the original Ti3C2T... x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) x The long-cycle stability test results (10,000 charge-discharge cycles) of the three samples at a current density of 10 A / g are shown in the figure. Figure 16 As shown, after 10,000 cycles, the IO-Ti3C2T x The capacitance retention rate was reduced from the original Ti3C2T x The efficiency was significantly increased from 80% to 96%, demonstrating excellent electrochemical cycling stability.

[0074] In step 1, the original Ti3C2T x Powder, O-Ti3C2T after oxidation in step 2 x Thin films and frozen aerogels / films (IO-Ti3C2T) xThe elemental analysis results of energy-dispersive X-ray spectroscopy (EDS) for the three samples are shown in Table 1. Sulfur (S) was not detected in the original sample. After proton-sulfate coupled oxidation treatment, O-Ti3C2T... x and IO-Ti3C2T x The atomic percentages of sulfur in the samples were only 0.01% and 0.03%, respectively. Considering the detection limit and instrument error of EDS testing, these values ​​are extremely low, indicating that the final product contains almost no sulfur residue. In Table 1, "-" indicates that sulfur was not detected.

[0075] Table 1 Different Ti3C2T x Atomic percentage of each constituent element in the sample

[0076] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon titanate electrode with a hierarchical porous structure, characterized in that, Includes the following steps: S1: Add titanium aluminum carbide powder to a mixed solution containing LiF and HCl to selectively etch away the Al atomic layer; repeatedly centrifuge and wash the precipitate until the pH of the supernatant reaches above 6; place the precipitate in water for ultrasonic peeling; centrifuge to collect the upper colloid to obtain Ti3C2T. x Dispersion; S2: To the Ti3C2T x Sulfuric acid solution was added to the dispersion for oxidative modification to obtain a modified suspension, which was then vacuum dried at 35 °C to 45 °C and vacuum filtered to obtain O-Ti3C2T loaded on a filter membrane. x film; S3: The O-Ti3C2T loaded on the filter membrane x The film was vacuum dried at a cold trap temperature of -40 ℃ to -50 ℃ for more than 24 hours to obtain an aerogel / film with a hierarchical porous structure; S4: Peel the aerogel / film with a hierarchical porous structure from the filter membrane to obtain a carbon titanate electrode with a hierarchical porous structure.

2. The method for preparing a titanium-carbon electrode with a hierarchical porous structure according to claim 1, characterized in that, In step S1, the titanium aluminum carbide powder is added to the mixed solution containing LiF and HCl, and the mixture is stirred and reacted at 30°C to 40°C for more than 24 hours.

3. The method for preparing a carbon titanate electrode with a hierarchical porous structure according to claim 1, characterized in that, In S2, the molar concentration of the sulfuric acid solution is between 2 mol / L and 4 mol / L.

4. The method for preparing a carbon titanate electrode with a hierarchical porous structure according to claim 1, characterized in that, In S2, the Ti3C2T x The volume ratio of the dispersion to the sulfuric acid solution is 0.5 to 2.

5. The method for preparing a titanium-carbon electrode with a hierarchical porous structure according to claim 1, characterized in that, In step S2, the modified suspension is vacuum dried at 35°C to 45°C for more than 48 hours until a mixed dough state is obtained.

6. The method for preparing a titanium-carbon electrode with a hierarchical porous structure according to claim 1, characterized in that, In S2, the O-Ti3C2T x The film contains uniformly distributed nanoscale in-plane mesopores with pore sizes ranging from 2 nm to 50 nm and additional interlayer micropore channels with pore sizes less than 2 nm.

7. The method for preparing a titanium-carbon electrode with a hierarchical porous structure according to claim 1, characterized in that, In step S3, the vacuum degree of the vacuum drying is 1 Pa to 2 Pa.

8. The method for preparing a carbon titanate electrode with a hierarchical porous structure according to claim 1, characterized in that, In S3, the aerogel / film has macroporous channels with a pore size greater than 50 nm inside.

9. A titanium-carbon electrode with a hierarchical porous structure, characterized in that, It is prepared using the method for preparing a titanium-carbon electrode with a hierarchical porous structure as described in any one of claims 1-8.

10. The application of a titanium carbon electrode with a hierarchical porous structure as described in claim 9 in the field of self-supporting electrodes.

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