Co-intercalation MXene in-situ synergistic growth CNTs / SiOx composite material and preparation method and application thereof

Abstract

The invention belongs to the technical field of silicon-carbon negative electrodes of lithium ion batteries, and relates to a co-intercalation MXene in-situ synergistic growth CNTs / SiOx composite material as well as a preparation method and application thereof. According to an in-situ synergistic growth mechanism, through a functional organosilicon polymer / CoCl2 co-intercalation strategy, SiOx and CNTs are generated between MXene layers at the same time, and a unique CNTs / SiOx / Ti3C2Tx three-dimensional composite structure is formed. The CNTs provide a conductive network, the SiOx contributes high specific capacity, the MXene substrate buffers volume expansion, and through the synergistic effect of the CNTs, the SiOx and the MXene substrate, the electrochemical performance of the material is remarkably improved (the first discharge specific capacity is larger than 650 mAh g <-1 >).

Description

Technical Field

[0001] This invention belongs to the field of silicon-carbon anode technology for lithium-ion batteries, and relates to a method for in-situ synergistic growth of CNTs / SiO2 with co-intercalated MXene. x Composite materials, their preparation methods, and applications. Background Technology

[0002] As the global energy structure accelerates its transition to cleaner energy, the increasing proportion of renewable energy generation places higher demands on large-scale energy storage technologies. Among numerous electrochemical energy storage systems, lithium-ion batteries have become the mainstream choice due to their excellent overall performance; however, their energy density is gradually becoming insufficient to meet the development needs of electric vehicles, smart grids, and other fields. According to the International Energy Agency (IEA), the global energy density of power batteries needs to reach over 350 Wh / kg by 2030, which poses new technological challenges to anode material systems.

[0003] Currently, commercially available lithium-ion batteries commonly use graphite-based anode materials, but their theoretical specific capacity is only 372 mAh / g, and their compaction density is approaching the theoretical limit. Although surface modification and particle shaping techniques can improve performance to a limited extent, it is inherently difficult to overcome the limitations of the material's intrinsic properties. Silicon-based materials, due to their ultra-high theoretical specific capacity (SiO2), offer a solution. x 2400-3600mAh / g) and suitable operating potential (0.1-0.4V vs. Li + Lithification (SiO₂) is considered the most promising alternative for industrialization; however, its industrialization faces two major obstacles: structural stability issues and the anisotropic volume expansion (SiO₂) that occurs during lithiation. x The low intrinsic conductivity (~200%) leads to electrode structure damage; charge transport limitation: low intrinsic conductivity causes severe polarization, resulting in a sharp decrease in capacity during high-current charge and discharge. To address these issues, existing technologies mainly employ the following three improvement paths, but all have significant shortcomings: the nano-sizing strategy has the advantage of reducing absolute volume change, but its drawback is reduced tap density (<1.0 g / cm³). 3 Furthermore, the high specific surface area exacerbates side reactions; carbon composite technology has the advantage of improving conductivity, but the carbon-silicon interface is weak, leading to phase separation after cycling; Wei et al. prepared MXene-Si-CNT composite materials containing 60wt% silicon using a simple ball milling method. Due to the presence of these double bonds and the multidimensional structure, its cycling stability was significantly improved, but ball milling uniformity was difficult to control, high silicon loading still had expansion problems, and long-term cycling still had double bond stability issues. MXene coating can utilize the mechanical strength of MXene to buffer stress, but the stacking of MXene sheets hinders ion transport.

[0004] Chinese patent application document (CN118240376A) discloses a method based on Ti3C2T x The patented three-layer inverted conical terahertz wave absorbing material relies on the immiscibility of PDMS / PTFE to form the interlayer interface. However, the interlayer bonding is weak, and it is prone to delamination or cracking under long-term bending or humid and hot environments. Furthermore, spin coating, embossing, and demolding require extremely high precision in mold processing, and the demolding process can easily damage the structure, especially the three-layer interface on the sidewalls. The periodicity and dimensional consistency of the conical structure are difficult to guarantee in large-area fabrication, which may lead to fluctuations in absorption performance.

[0005] Chinese patent application (CN119503806A) discloses a two-dimensional layered MXene nanosheet and its preparation method. While this patent offers an improved method for preparing high-quality MXene nanosheets, it suffers from significant shortcomings in terms of process cost, functional balance, evidentiary strength, and environmental friendliness. Its technical solution appears more like an optimization of existing processes than an innovation, and may face challenges in practical applications and market competition. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a method for in-situ synergistic growth of CNTs / SiO2 with co-intercalated MXene. x Composite materials, SiO2 grown in situ x With uniform distribution between layers, CNTs form a three-dimensional conductive framework in situ, MXene is confined between layers to suppress expansion, and intercalation-pyrolysis-catalysis are realized simultaneously. This innovative intercalation-in-situ growth strategy has breakthroughs in structural design, process simplification and performance improvement, providing a new approach for the development of high-energy-density lithium-ion battery anode materials.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A co-intercalated MXene in-situ synergistic growth method for CNTs / SiO x The composite material includes an MXene framework, a CNT conductive network, and SiO2. x The tertiary structure of the active unit.

[0009] The present invention also provides an in-situ co-grown CNTs / SiO2 co-intercalation method using the aforementioned co-intercalated MXene. x A method for preparing composite materials, the method comprising the following steps:

[0010] S1 and Ti3AlC2 were etched in hydrofluoric acid containing LiCl and then washed to obtain multilayer Ti3C2T. x ;

[0011] S2, Multilayer Ti3C2Tx The mixture is mixed with an intercalating agent, and then separated, washed, centrifuged, filtered, and dried to obtain the intercalated product.

[0012] S3. The intercalation product is subjected to high-temperature annealing to obtain co-intercalated MXene in-situ synergistic growth of CNTs / SiO x Composite materials.

[0013] The above-mentioned co-intercalated MXene in-situ synergistic growth of CNTs / SiO x In the preparation method of the composite material, in step S1, the concentration of hydrofluoric acid is 1–20 mol / mL, and the amount of LiCl added is 0.001–1.2 g / mL. The purpose of adding LiCl is to initially open the interlayer spacing through pre-intercalation and to introduce Li... + Facilitates subsequent cation exchange, enabling functionalized organosilicon polymers and Co. 2+ It enters the MXene interlayer through ion exchange.

[0014] Preferably, the etching time is 1-48 hours, the rotation speed is 100-2000 rpm, and the temperature is 20-45℃.

[0015] The above-mentioned co-intercalated MXene in-situ synergistic growth of CNTs / SiO x In the preparation method of the composite material, in step S1, the mass ratio of Ti3AlC2 to LiCl is 1:(0.1-30).

[0016] This mass ratio was strictly controlled within a wide range of 1:(0.1-30) for optimization in order to find an optimal ratio that determines the initial interlayer spacing and the amount of Li available for ion exchange. + The quantity directly affects the functionalization of organosilicon polymers and Co. 2+ The amount and uniformity of intercalation determine the CNTs and SiO2 generated after final annealing. x The quality and distribution of the material ultimately determine the performance of the composite material's tertiary structure, enabling the synergistic process from etching and intercalation to the final in-situ growth, thus successfully preparing composite materials with ideal microstructure and excellent electrochemical performance.

[0017] The above-mentioned co-intercalated MXene in-situ synergistic growth of CNTs / SiO x In the preparation method of the composite material, in step S2, the intercalating agent is a functionalized organosilicon polymer and a metal catalyst with a mass ratio of (2-20):(0.005-0.5).

[0018] The above-mentioned co-intercalated MXene in-situ synergistic growth of CNTs / SiO xIn the preparation method of the composite material, the functionalized organosilicon polymer is one of poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane] and poly(dimethylsiloxane), bis(3-aminopropyl)-terminated;

[0019] And / or metal catalysts include at least one of cobalt chloride, ferric chloride, and nickel chloride.

[0020] As a preferred option, the metal catalyst is cobalt chloride.

[0021] This invention utilizes hydrofluoric acid etching to prepare multilayer Ti3C2T x Wet precipitation was used as the main intercalation material, and functionalized organosilicon polymers and cobalt chloride (CoCl2) were used as composite intercalating agents, with the functionalized organosilicon polymers also serving as the reaction solvent. Based on the principle of cation exchange, the functionalized organosilicon polymers and CoCl2 were... 2+ Common insertion and retention in Ti3C2T x Intercalation products are formed between layers; the core advantage of these intercalation products lies in their ingenious design, which pre-assembles precursors (carbon silicon sources, catalysts) with different functions within the MXene nanoreactor. This directly leads to the in-situ, synergistic growth of CNTs / SiO₂ with ideal structures and tightly bound components during subsequent heat treatment. x / MXene ternary composite material.

[0022] Preferably, during the mixing process in step S2, the stirring speed is 100-800 rpm and the time is 2-96 h; then the intercalated product is washed with an organic solvent, and the centrifuge speed is 1000-8000 rpm during the washing process, and the product is washed 4-8 times to clean the multilayer MXene intercalated product.

[0023] Further preferably, the organic solvent includes at least one of methanol, ethanol, propanol, and isopropanol.

[0024] In this invention, the control of process parameters in the chemical intercalation process is crucial, specifically manifested in: optimized control of the magnetic stirring speed and precise regulation of the intercalation time: a stirring speed exceeding 800 rpm or an intercalation time exceeding 96 h will lead to Ti3C2T x Excessive stripping increases the proportion of few-layer MXene and weakens Ti3C2T. x Interlayer structure of SiO x The volume expansion buffering effect; if the stirring speed is below 100 rpm or the intercalation time is less than 2 hours, it is difficult to achieve sufficient intercalation. Insufficient intercalation will lead to the functionalization of organosilicon polymers and Co. 2+ Uneven distribution and incomplete intercalation will affect the interaction between CNTs and SiO2 during subsequent annealing. x The uniform distribution.

[0025] The above-mentioned co-intercalated MXene in-situ synergistic growth of CNTs / SiO x In the preparation method of the composite material, in step S2, multilayer Ti3C2T x The mass ratio of the additive to the intercalating agent is (0.3-0.5):(1.5-21). In this step, if there is too little additive, there will not be enough functionalized organosilicon polymer molecules to expand all the interlayers of MXene, resulting in incomplete intercalation and uneven distribution of the catalyst intercalating agent; if there is too much intercalating agent, it will lead to excessive exfoliation of the structure, catalyst agglomeration and imbalance of component ratio.

[0026] The above-mentioned co-intercalated MXene in-situ synergistic growth of CNTs / SiO x In the preparation method of the composite material, step S3 involves high-temperature annealing in an Ar and H2 atmosphere; and it is divided into two stages.

[0027] First stage annealing: Heat to 200-600℃ at a rate of 1-20℃ / min, and hold for 10-120min;

[0028] Second stage annealing: Increase the temperature to 400-800℃ at a rate of 5-20℃ / min, and hold for 60-480min.

[0029] A two-stage annealing strategy was employed to order the reaction pathway: the first step separated the reduction / crosslinking curing from the second step's catalytic growth / final transformation, two processes with different kinetic and thermodynamic requirements, thus achieving reaction controllability. Microstructure optimization through two-stage annealing ensured the optimal formation of SiO₂. x The nano-sizing and uniform distribution of MXene, along with the efficient construction of CNT networks, ensures material integrity protection: the gentle first stage maximizes the preservation of the layered framework structure of MXene, laying the foundation for its role as a buffer and conductive framework.

[0030] Preferably, the second-stage insulation temperature is higher than the first-stage insulation temperature.

[0031] The above-mentioned co-intercalated MXene in-situ synergistic growth of CNTs / SiO x In the preparation method of composite materials, the Ar flow rate in the first stage of annealing is 100-500 sccm, and the H2 flow rate is 10-100 sccm;

[0032] In the second stage of annealing, the Ar flow rate is 10-200 sccm, the H2 flow rate is 10-100 sccm, and the total flow rate is 100-300 sccm. Co is achieved through H2. 2+ For reduction, Ar serves as a protective gas in the gaseous atmosphere, and the total gas flow rate should not be too large, so that the cracked carbon source can be retained and deposited.

[0033] The present invention also provides a high energy density lithium-ion battery anode material, wherein the anode material comprises the above-mentioned composite material or the composite material prepared by the above-mentioned method.

[0034] As a preferred option, CNTs / SiO2 are co-intercalated MXenes for in-situ synergistic growth. x The negative electrode material prepared from composite materials has a 100 mAg content in a 2032R coin cell. -1 The initial discharge specific capacity can reach 650 mAh g at the current density. -1 above.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. This invention employs a composite intercalating agent design: the functionalized organosilicon polymer functions as both an intercalating agent and a solvent, simplifying the process; the introduction of CoCl2 enables in-situ generation of Co nanoparticles, catalyzing CNT growth. Cation exchange intercalation ensures the interaction between the functionalized organosilicon polymer and Co. 2+ Uniform distribution avoids the component segregation problem in traditional methods.

[0037] 2. The in-situ synergistic growth mechanism of the present invention: SiO is simultaneously generated between MXene layers through a functionalized organosilicon polymer / CoCl2 co-intercalation strategy. x Together with CNTs, they form a unique CNTs / SiO2 / C ... x / Ti3C2T x Three-dimensional composite structure. CNTs provide the conductive network, SiO x The high specific capacity, the MXene substrate buffering volume expansion, and the synergistic effect of these three factors significantly improve the material's electrochemical performance (initial discharge specific capacity > 650 mAh g). -1 ).

[0038] 3. This invention employs a one-step in-situ synthesis method: SiO is simultaneously synthesized in a single high-temperature annealing step. x Pyrolysis and CNT catalytic growth avoid the complexity and pollution risks of multi-step processing. It boasts high raw material utilization: functionalized organosilicon polymers are pyrolyzed to generate SiO₂. x At the same time, its decomposition products, such as carbon sources, participate in the formation of CNTs, thereby maximizing the utilization of resources.

[0039] 4. This invention employs a two-stage heating process in CVD in-situ growth. The first stage is to allow the Co layers between the MXene layers to heat up. 2+ The first stage completely reduces the functionalized organosilicon polymer to elemental Co and enables cross-linking and curing. The second stage is to decompose the functionalized organosilicon polymer and provide a stable temperature for CNT growth, thus promoting better CNT growth. The two-stage heating can better leverage the catalytic effect of Co particles.

[0040] 5. The high specific capacity and conductivity constructed in this invention, along with enhanced interface stability: the high conductivity of MXene and the permeation network of CNTs synergistically improve electron transport efficiency, SiO x The high theoretical capacity is fully utilized, far exceeding that of pure MXene or SiO. x Anode material; Enhanced interface stability: SiO x MXene forms a tight interface through in-situ growth, reducing contact resistance, while CNTs suppress SiO₂. x Particle agglomeration further improves cycle performance. Attached Figure Description

[0041] Figure 1 These are comparative examples 1 and examples 1-2 of the present invention, respectively, after annealing of multilayer Ti3C2T. x 1-CNTs / SiO x / Ti3C2T x 2-CNTs / SiO x / Ti3C2T x SEM image;

[0042] Figure 2 The intercalation products in Comparative Example 1 and Examples 1-2 of this invention, and the annealed multilayer Ti3C2T, are respectively... x 1-CNTs / SiO x / Ti3C2T x 2-CNTs / SiO x / Ti3C2T x EDS energy dispersive spectroscopy analysis of the composite material;

[0043] Figure 3 These are the intercalation products from Examples 1-2 and Comparative Example 1 of the present invention, and the annealed multilayer Ti3C2T, respectively. x 1-CNTs / SiO x / Ti3C2T x 2-CNTs / SiO x / Ti3C2T x XRD patterns of composite materials;

[0044] Figure 4 The 1-CNTs / SiO2 after annealing in Examples 1-2 of this invention x / Ti3C2T x 2-CNTs / SiO x / Ti3C2T x High-resolution XPS spectra of composite materials;

[0045] Figure 5For the application of this invention, the annealed multilayer Ti3C2T in Comparative Example 1 and Examples 1-2 x 1-CNTs / SiO x / Ti3C2T x 2-CNTs / SiO x / Ti3C2T x Testing of the electrochemical cycling performance of composite materials.

[0046] Figure 6 The intercalation product PDMS3-CoCl2-Ti3C2T obtained in Example 5 x XRD pattern and EDS energy dispersive spectroscopy analysis. Detailed Implementation

[0047] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0048] To make the objectives, technical solutions, and advantages of this invention patent clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this invention patent and are not intended to limit the scope of this invention patent.

[0049] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0050] The terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., used in this invention refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms are not necessarily directed at the same embodiment or example. Furthermore, the technical features involved in the various embodiments of the invention can be combined with each other as long as they do not conflict with each other.

[0051] The following describes in further detail, through specific embodiments, the in-situ synergistic growth of CNTs / SiO2 with co-intercalated MXene according to the present invention. x Preparation methods of composite materials.

[0052] Poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane] and poly(dimethylsiloxane), bis(3-aminopropyl)-terminated, were purchased from Aladdin; the structural formula of poly(dimethylsiloxane), bis(3-aminopropyl)-terminated is shown below:

[0053]

[0054] Example 1:

[0055] It includes a PDMS / CoCl2 co-intercalated MXene in-situ synergistic growth of CNTs / SiO2. x Methods for preparing composite materials include:

[0056] The CNTs / SiO obtained in this embodiment x / Ti3C2T x denoted as 1-CNTs / SiO x / Ti3C2T x .

[0057] S1: Etching of 400-mesh Ti3AlC2 was performed using hydrofluoric acid etching method. Specifically, 100 mL of 10 wt% hydrofluoric acid was added to a polytetrafluoroethylene bottle and magnetically stirred for 15 minutes. After stirring, 2 g of LiCl was added and stirred at a constant temperature of 25°C for 15 minutes. Then, 2 g of Ti3AlC2 was slowly added over 10 minutes to prevent rapid addition from generating violent exothermic reactions. The etching was performed with magnetic stirring for 24 hours at a speed of 500 rpm and a constant temperature of 25°C.

[0058] S2: Divide the etched liquid from S1 into four centrifuge tubes, wash twice with 6M / L hydrochloric acid, then wash twice with deionized water, centrifuge again, and collect the precipitate. Collect the bottom precipitate as a multilayer Ti3C2T. x The centrifugation speed was 5000 rpm for 5 minutes.

[0059] S3: Preparation of intercalation products, using 0.5g of multilayer Ti3C2T x The precipitate was mixed with 10 g of poly(dimethylsiloxane), bi(3-aminopropyl)-terminated, and 0.025 g of CoCl2 in a magnetic stirrer at 200 rpm for 24 h. The intercalation product was then separated into two centrifuge tubes, washed five times with isopropanol, and centrifuged to obtain the black precipitate layer, yielding multilayer Ti3C2T. x The intercalation products were collected using a nylon organic filter membrane and cured in a vacuum oven at 100°C for 5 hours. After drying, the intercalation product PDMS1-CoCl2-Ti3C2T was obtained. x ;

[0060] S4: The above-mentioned annealing precursor PDMS1-CoCl2-Ti3C2T x The alumina crucible was placed in an alumina boat and then placed into a tube furnace for high-temperature annealing. The chamber was evacuated at room temperature to a pressure below 100 Pa, then Ar gas was introduced to restore the chamber to atmospheric pressure and remove other gases. After Ar purging for 15 minutes, heating was initiated and H2 was introduced at flow rates of 150 sccm and 50 sccm. The temperature was increased from room temperature to 300℃ at a rate of 5℃ / min and held for 30 min, then increased to 700℃ at a rate of 10℃ / min and held for 120 min. The chamber pressure was maintained at 5 × 10⁻⁶ Pa. 4 The gas flow rate was 50 sccm, and the total flow rate was 200 sccm. After the heat treatment, H2 was cooled to room temperature in an Ar atmosphere at a flow rate of 200 sccm, resulting in high-temperature annealed 1-CNTs / SiO2. x / Ti3C2T x Composite materials.

[0061] Figure 1 b represents the 1-CNTs / SiO obtained in Example 1. x / Ti3C2T x The SEM image shows the successful growth of CNTs between MXene layers.

[0062] Figure 2 b and e are respectively obtained from Example 1: PDM1-CoCl2-Ti3C2T x 1-CNTs / SiO x / Ti3C2T x EDS energy dispersive spectroscopy analysis. The figure shows that the changes in Si and Co elemental content indicate that PDMS successfully recombines with MXene.

[0063] Figure 3 The PDMSI-CoCl2-Ti3C2T obtained in Example 1 of 3b and 3b x 1-CNTs / SiO x / Ti3C2T x The XRD patterns are shown in the figure. The changes in the MXene interlayer spacing indicate that PDMS and CoCl2 were successfully inserted into the interlayer.

[0064] Figure 4 a is the 1-CNTs / SiO obtained in Example 1. x / Ti3C2T x The high-resolution XPS spectrum shows the presence of Si in its valence state.

[0065] Figure 5 The 1-CNTs / SiO obtained in Example 1 x / Ti3C2T x As shown in the figure, the cycling performance test revealed a significant improvement in the cycling capacity of the prepared sample.

[0066] Example 2:

[0067] It includes a PDMS / CoCl2 co-intercalated MXene in-situ synergistic growth of CNTs / SiO2. x Methods for preparing composite materials include:

[0068] The difference from Example 1 is that the intercalating agent used in S3 is poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane](PDMS2). The CNTs / SiO2 obtained in this example... x 2-CNTs / SiO2 grown in situ between MXene layers x / Ti3C2T x Composite materials.

[0069] S1: Etching of 400-mesh Ti3AlC2 was performed using hydrofluoric acid etching method. Specifically, 100 mL of 10 wt% hydrofluoric acid was added to a polytetrafluoroethylene bottle and magnetically stirred for 15 minutes. After stirring, 2 g of LiCl was added and stirred at a constant temperature of 25°C for 15 minutes. Then, 2 g of Ti3AlC2 was slowly added over 10 minutes to prevent rapid addition from generating violent exothermic reactions. The etching was performed with magnetic stirring for 24 hours at a speed of 500 rpm and a constant temperature of 25°C.

[0070] S2: The etched liquid from S1 was divided into four centrifuge tubes, washed twice with 6M / L hydrochloric acid, then twice with deionized water, and then centrifuged again to collect the precipitate. The bottom precipitate was collected to obtain multilayer Ti3C2T. x The centrifugation speed was 5000 rpm for 5 minutes.

[0071] S3: Preparation of intercalation products, using 0.40g of multilayer Ti3C2T x The precipitate was mixed with 10 g of poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane] and 0.025 g of CoCl2 in a magnetic stirrer at 200 rpm for 24 h. The intercalation product was then separated into two centrifuge tubes, washed five times with isopropanol, and centrifuged to obtain the black precipitate layer, yielding multilayer Ti3C2T. x The intercalation products were collected using a nylon organic filter membrane and cured in a vacuum oven at 100°C for 5 hours. After drying, the intercalation product PDMS2-CoCl2-Ti3C2T was obtained. x ;

[0072] S4: The above-mentioned annealing precursor PDMS2-CoCl2-Ti3C2T x The alumina crucible was placed in an alumina boat and then placed into a tube furnace for high-temperature annealing. The chamber was evacuated at room temperature to a pressure below 100 Pa, then Ar gas was introduced to restore the chamber to atmospheric pressure and remove other gases. After Ar purging for 15 minutes, heating was initiated and H2 was introduced at flow rates of 150 sccm and 50 sccm. The temperature was increased from room temperature to 300℃ at a rate of 5℃ / min and held for 30 min, then increased to 700℃ at a rate of 10℃ / min and held for 120 min. The chamber pressure was maintained at 5 × 10⁻⁶ Pa. 4 The gas flow rate was 50 sccm, and the total flow rate was 200 sccm. After the heat treatment, H2 was cooled to room temperature in an Ar atmosphere at a flow rate of 200 sccm, resulting in high-temperature annealed 2-CNTs / SiO2. x / Ti3C2T x Composite materials.

[0073] Figure 1 c represents the 2-CNTs / SiO obtained in Example 2. x / Ti3C2T x The SEM image shows the successful growth of CNTs between MXene layers.

[0074] Figure 2 c and f are respectively obtained from PDMS2-CoCl2-Ti3C2T in Example 2. x 2-CNTs / SiO x / Ti3C2T x EDS energy dispersive spectroscopy analysis. The figure shows that the changes in Si and Co elemental content indicate that PDMS successfully recombines with MXene.

[0075] Figure 3 The PDMS2-CoCl2-Ti3C2T obtained in Example 2 of 3b and 3b x 2-CNTs / SiO x / Ti3C2T x The XRD patterns are shown in the figure. The changes in the MXene interlayer spacing indicate that PDMS and CoCl2 were successfully inserted into the interlayer.

[0076] Figure 4 b represents the 2-CNTs / SiO obtained in Example 2. x / Ti3C2T xThe high-resolution XPS spectrum shows the presence of Si in various valence states.

[0077] Figure 5 The 2-CNTs / SiO obtained in Example 2 x / Ti3C2T x Cyclic performance testing. As can be seen from the figure, the cycling capacity of the prepared sample is significantly improved.

[0078] Example 3:

[0079] It includes a PDMS / CoCl2 co-intercalated MXene in-situ synergistic growth of CNTs / SiO2. x Methods for preparing composite materials include:

[0080] S1: Etching of 400-mesh Ti3AlC2 was performed using hydrofluoric acid etching method. Specifically, 100 mL of 10 wt% hydrofluoric acid was added to a polytetrafluoroethylene bottle and magnetically stirred for 15 minutes. After stirring for 15 minutes, 2 g of LiCl was added and stirred at a constant temperature of 25°C for another 15 minutes. Then, 2 g of Ti3AlC2 was slowly added over 10 minutes to prevent rapid addition from generating violent exothermic reactions. The etching was performed with magnetic stirring for 24 hours at a speed of 450 rpm and a constant temperature of 25°C.

[0081] S2: The etched liquid from S1 was divided into four centrifuge tubes, washed twice with 6M / L hydrochloric acid, then twice with deionized water, and then centrifuged again to collect the precipitate. The bottom precipitate was collected to obtain multilayer Ti3C2T. x The centrifugation speed was 5000 rpm for 5 minutes.

[0082] S3: Preparation of intercalation products, using 0.2g of multilayer Ti3C2T x The precipitate was mixed with 10 g of poly(dimethylsiloxane), bis(3-aminopropyl)-terminated, and 0.025 g of CoCl2 in a magnetic stirrer at 200 rpm for 72 h. The intercalation product was then separated into two centrifuge tubes, washed five times with isopropanol, and centrifuged to obtain the black precipitate layer, yielding multilayer Ti3C2T. x The intercalation products were collected using a nylon organic filter membrane and cured in a vacuum oven at 100°C for 5 hours. After drying, PDMS1-CoCl2-Ti3C2T was obtained. x ;

[0083] S4: The above-mentioned annealing precursor PDMS1-CoCl2-Ti3C2T xThe alumina crucible was placed in an alumina boat and then placed into a tube furnace for high-temperature annealing. The chamber was evacuated at room temperature to a pressure below 100 Pa, then Ar gas was introduced to restore the chamber to atmospheric pressure and remove other gases. After Ar purging for 15 minutes, heating was initiated and H2 was introduced at flow rates of 170 sccm and 30 sccm. The temperature was increased from room temperature to 300℃ at a rate of 5℃ / min and held for 30 min, then increased to 650℃ at a rate of 10℃ / min and held for 120 min. The chamber pressure was maintained at 5 × 10⁻⁶ Pa. 4 The gas flow rate was 50 sccm, and the total flow rate was 200 sccm. After the heat treatment, H2 was cooled to room temperature in an Ar atmosphere at a flow rate of 200 sccm, resulting in high-temperature annealed 1-CNTs / SiO2. x / Ti3C2T x Composite materials.

[0084] Example 4:

[0085] It includes a PDMS / CoCl2 co-intercalated MXene in-situ synergistic growth of CNTs / SiO2. x Methods for preparing composite materials include:

[0086] S1: Etching of 400-mesh Ti3AlC2 was performed using hydrofluoric acid etching method. Specifically, 100 mL of 10 wt% hydrofluoric acid was added to a polytetrafluoroethylene bottle and magnetically stirred for 15 minutes. After stirring for 15 minutes, 2 g of LiCl was added and stirred at a constant temperature of 25°C for another 15 minutes. Then, 2 g of Ti3AlC2 was slowly added over 10 minutes to prevent rapid addition from generating violent exothermic reactions. The etching was performed with magnetic stirring for 24 hours at a speed of 700 rpm and a constant temperature of 25°C.

[0087] S2: The etched liquid from S1 was divided into four centrifuge tubes, washed twice with 6M / L hydrochloric acid, then twice with deionized water, and then centrifuged again to collect the precipitate. The bottom precipitate was collected to obtain multilayer Ti3C2T. x The centrifugation speed was 5000 rpm for 5 minutes.

[0088] S3: Preparation of intercalation products, using 0.4g of multilayer Ti3C2T x The precipitate was mixed with 10 g of poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane] and 0.035 g of CoCl2 in a magnetic stirrer at 200 rpm for 60 h. The intercalation product was then separated into two centrifuge tubes, washed five times with isopropanol, and centrifuged to obtain the black precipitate layer, yielding multilayer Ti3C2T. xThe intercalation products were collected using a nylon organic filter membrane and cured in a vacuum oven at 100°C for 5 hours. After drying, PDMS2-CoCl2-Ti3C2T was obtained. x ;

[0089] S4: The above PDMS2-CoCl2-Ti3C2T x The material is placed in an alumina crucible, which is then placed in an alumina boat and sent into a tube furnace for in-situ SiO2 growth via CVD high-temperature annealing. x The chamber was evacuated to a pressure below 100 Pa at room temperature. Ar gas was then introduced to restore the chamber to atmospheric pressure, removing any remaining gases. After Ar purging for 15 minutes, heating was initiated, and H2 was introduced at flow rates of 120 sccm and 80 sccm. The temperature was increased from room temperature to 700℃ at a rate of 5℃ / min and held for 120 min, while maintaining the chamber pressure at 4 × 10⁻⁶ Pa. 4 Pa, after the heat preservation was completed, H2 was cooled to room temperature in an Ar atmosphere at a flow rate of 200 sccm to obtain CNTs / SiO. x 2-CNTs / SiO2 grown in situ between MXene layers x / Ti3C2T x Composite materials.

[0090] Example 5:

[0091] The only difference from Example 1 is that the intercalating agent is polydimethylsiloxane (purchased from Macklin), which includes a PDMS3 / CoCl2 co-intercalation MXene for in-situ synergistic growth of CNTs / SiO2. x Methods for preparing composite materials:

[0092] S1: Etching of 400-mesh Ti3AlC2 was performed using hydrofluoric acid etching method. Specifically, 100 mL of 10 wt% hydrofluoric acid was added to a polytetrafluoroethylene bottle and magnetically stirred for 15 minutes. After stirring, 2 g of LiCl was added and stirred at a constant temperature of 25°C for 15 minutes. Then, 2 g of Ti3AlC2 was slowly added over 10 minutes to prevent rapid addition from generating violent exothermic reactions. The etching was performed with magnetic stirring for 24 hours at a speed of 500 rpm and a constant temperature of 25°C.

[0093] S2: Divide the etched liquid from S1 into four centrifuge tubes, wash twice with 6M / L hydrochloric acid, then wash twice with deionized water, centrifuge again, and collect the precipitate. Collect the bottom precipitate as a multilayer Ti3C2T. x The centrifugation speed was 5000 rpm for 5 minutes.

[0094] S3: Preparation of intercalation products, using 0.5g of multilayer Ti3C2T x The precipitate was mixed with 10 g of polydimethylsiloxane (purchased from Macklin) (unfunctionalized) and 0.025 g of CoCl2 in a magnetic stirrer at 200 rpm for 24 h. The intercalation product was then aliquoted into two centrifuge tubes, washed five times with isopropanol, and centrifuged to obtain the black precipitate layer, yielding multilayer Ti3C2T. x The intercalation products were collected using a nylon organic filter membrane and cured in a vacuum oven at 100°C for 5 hours. After drying, the intercalation products were obtained.

[0095] S4: Place the intercalated product into an alumina crucible, then place the alumina crucible in an alumina boat and send it into a tube furnace for high-temperature annealing. Evacuate the chamber at room temperature to a pressure below 100 Pa, then turn on Ar to restore the chamber to atmospheric pressure to remove other gases. After Ar purging for 15 minutes, begin heating and introduce H2 at flow rates of 150 sccm and 50 sccm respectively. Increase the temperature from room temperature to 300℃ at a rate of 5℃ / min and hold for 30 min, then increase the temperature to 700℃ at a rate of 10℃ / min and hold for 120 min. Maintain the chamber pressure at 5 × 10⁻⁶ Pa. 4 The gas flow rate was 50 sccm, and the total flow rate was 200 sccm. After the heat preservation was completed, H2 was cooled to room temperature in an Ar atmosphere at a flow rate of 200 sccm to obtain the high-temperature annealed composite material.

[0096] Figure 6 a is the PDMS3-CoCl2-Ti3C2T obtained in Example 5. x The XRD pattern shows that the interlayer spacing of MXene remained almost unchanged, indicating that PDMS and CoCl2 were not inserted into the interlayer.

[0097] Figure 6 b is the PDMS3-CoCl2-Ti3C2T obtained from Example 5. x EDS energy dispersive spectroscopy analysis was performed. The figure shows that the Si and Co content is almost zero, indicating that the intercalating agent did not enter the MXene interlayer.

[0098] In summary, Example 5 used unfunctionalized PDMS, whose inert molecular chains could not strongly interact with the MXene surface, causing the entire cation exchange-assisted intercalation process to fail. The resulting composite material contained almost no high-capacity active material (SiO₂). x ), no reinforced conductive networks (CNTs), and no interlayer buffer space to mitigate volume expansion.

[0099] Therefore, its overall electrochemical performance (capacity, rate capability) will be far lower than that of Examples 1 and 2, which were successfully intercalated, demonstrating that in this invention, the use of functionalized organosilicon polymers with polar functional groups is the key to achieving effective intercalation and obtaining high-performance composite materials.

[0100] Comparative Example 1:

[0101] Preparation of multilayer Ti3C2T x The methods for using materials include:

[0102] S1: Etching of 400-mesh Ti3AlC2 was performed using hydrofluoric acid etching method. Specifically, 100 mL of 10 wt% hydrofluoric acid was added to a polytetrafluoroethylene bottle and magnetically stirred for 15 minutes. After stirring, 2 g of LiCl was added and stirred at a constant temperature of 25°C for 15 minutes. Then, 2 g of Ti3AlC2 was slowly added over 10 minutes to prevent rapid addition from generating violent exothermic reactions. The etching was performed with magnetic stirring for 24 hours at a speed of 500 rpm and a constant temperature of 25°C.

[0103] S2: The etched liquid from S1 was divided into four centrifuge tubes, washed twice with 6M / L hydrochloric acid, then twice with deionized water, and then centrifuged again to collect the precipitate. The bottom precipitate was collected to obtain multilayer Ti3C2T. x The centrifugation speed was 5000 rpm for 5 minutes.

[0104] S3: The above-mentioned multilayer Ti3C2T x The alumina crucible was placed in an alumina boat and then placed in a CVD tube furnace for high-temperature annealing. The chamber was evacuated at room temperature to a pressure below 100 Pa, then Ar gas was introduced to restore the chamber to atmospheric pressure and remove other gases. After Ar purging for 15 minutes, heating was initiated and H2 was introduced at flow rates of 150 sccm and 50 sccm. The temperature was increased from room temperature to 300℃ at a rate of 5℃ / min and held for 30 min, then increased to 700℃ at a rate of 10℃ / min and held for 120 min. The chamber pressure was maintained at 5 × 10⁻⁶ Pa. 4 The gas flow rate was 50 sccm, and the total flow rate was 200 sccm. After the heat treatment, H2 was cooled to room temperature in an Ar atmosphere at a flow rate of 200 sccm, resulting in high-temperature annealed multilayer Ti3C2T. x Material.

[0105] Figure 1 a represents the multilayer Ti3C2T obtained in Comparative Example 1. x The SEM image shows that MXene, after high-temperature two-stage annealing, retains a multi-layered accordion structure.

[0106] Figure 2 a and d represent the multilayer Ti3C2T obtained from Comparative Example 1, respectively. x EDS energy dispersive spectroscopy analysis before and after annealing. The figure shows the types and proportions of elements in MXene after high-temperature two-stage annealing.

[0107] Figure 3 The multilayer Ti3C2T obtained in Comparative Example 1 in a and 3b x XRD patterns before and after annealing. The figure shows the interlayer spacing of MXene after high-temperature two-stage annealing.

[0108] from Figure 5 Multilayer Ti3C2T obtained in Comparative Example 1 x As shown in the graph, the annealed MXene has a lower cycle capacity.

[0109] Comparative Example 2:

[0110] Compared to Example 1, the only difference in Comparative Example 2 is that the preparation of the intercalation product was added in S3 and only PDMS1 was used as the intercalating agent. In this comparative example, PDMS1 can be intercalated between MXene layers, but no catalyst is introduced to catalyze the growth of CNTs after the two-stage annealing treatment, so the construction of CNTs between MXene layers cannot be achieved.

[0111] Comparative Example 3:

[0112] Compared to Example 2, the only difference in Comparative Example 3 is that the preparation of the intercalation product was added in S3 and only PDMS2 was used as the intercalating agent. In this comparative example, PDMS2 can be intercalated between MXene layers, but no catalyst is introduced to catalyze the growth of CNTs after the two-stage annealing treatment, so the construction of CNTs between MXene layers cannot be achieved.

[0113] Comparative Example 4:

[0114] Compared to Example 1, the only difference in Comparative Example 4 is the addition of the preparation of the intercalation product in S3 and the use of CoCl2 as the intercalating agent. This comparative example allows for CoCl2 intercalation between MXene layers, but it is less effective for growing SiO2. x CNTs lack silicon and carbon sources, thus preventing the realization of SiO2. x The construction of CNTs in the MXene layer.

[0115] Electrochemical performance tests were conducted on the materials from Examples 1-2 and Comparative Example 1. A CR2032 button cell was used, and assembly was completed in an argon-filled glove box. The working electrode was prepared as follows: A slurry was prepared by mixing the active material, acetylene black (Super-P), and 10% polyvinylidene fluoride (PVDF) in a weight ratio of 8:1:1, with NMP as the solvent in an 8:1:1 ratio, and coated onto a pure copper foil current collector. The coated electrode was dried in a vacuum oven at 80°C for 12 hours. The areal loading of the active material in the electrode was approximately 1.0 mg / cm³. -2 .

[0116] Figure 5 Examples 1-2 and Comparative Example 1 were prepared at 100 mAg. -1 Cyclic performance was characterized at current densities. It can be seen that the initial discharge capacity of the multilayer MXene after high-temperature annealing in Comparative Example 1 is approximately 170 mA hg. -1 The reversible capacity is 110mAh g. -1 Left and right. Example 1: 1-CNTs / SiO2 obtained after high-temperature annealing. x / Ti3C2T x The initial discharge capacity is approximately 450 mA hg -1 The reversible capacity is 225mAh g. -1 Left and right. Example 2: 2-CNTs / SiO2 obtained after high-temperature annealing. x / Ti3C2T x The initial discharge capacity is approximately 650 mAh g. -1 The reversible capacity is 290mAh g. -1 The comparison shows that the electrochemical performance discharge specific capacity of Examples 1 and 2 is significantly improved, increasing from 110 mA hg. -1 Upgraded to 290mAh g -1 It can be seen that Example 2 has the highest charge-discharge specific capacity.

[0117] Based on the above, it can be seen that in Examples 1 and 2, the intercalation product PDMS-CoCl2-Ti3C2T x CNTs / SiO2 composite material after precursor annealing x / Ti3C2T x It exhibits good electrochemical performance.

[0118] Example 1, by using PDMS1 and Co 2+ PDMS1-CoCl2-Ti3C2T as a co-intercalating agent and solvent x The intercalated product was used as a precursor for high-temperature annealing to obtain the composite material 1-CNTs / SiO. x / Ti3C2T xXRD analysis showed that the intercalation product PDMS1-CoCl2-Ti3C2T x The shift of the (002) peak to a lower angle directly proves the interaction between PDMS molecules and Co. 2+ Successful insertion into the MXene interlayer resulted in an increased interlayer spacing. EDS energy dispersive spectroscopy confirmed a significant change in Si content after CVD high-temperature annealing, indicating that PDMS underwent interlayer pyrolysis to generate SiO. x EDS energy dispersive spectroscopy confirmed that the Si content changed significantly after high-temperature annealing, indicating that PDMS underwent interlayer pyrolysis to generate SiO. x Furthermore, the Si content is positively correlated with the capacity: the prepared CNTs / SiO x / Ti3C2T x The Si content shown by EDS of composite materials directly reflects the active material SiO₂. x The loading amount is a key factor determining the specific capacity. The intercalation product directly affects the final performance. Example 2 shows a larger interlayer spacing and higher Si content, and its discharge specific capacity is significantly better than that of composite material 1.

[0119] Excessive intercalation leads to excessive MXene stripping, increasing the proportion of few-layer MXene, which in turn reduces the yield of intercalated products and weakens the interlayer structure's effect on SiO. x The buffering effect of volume expansion. CNTs have a synergistic effect, the carbon nanotube network generated by Co catalysis provides a conductive pathway, and the MXene framework maintains structural stability. The three work together to achieve high capacity and good cycling performance.

[0120] In summary, this invention provides an innovative in-situ synergistic growth method for CNTs / SiO2 ... x The composite material was successfully prepared by combining cation exchange intercalation with in-situ chemical vapor deposition (CVD) pyrolysis, resulting in the fabrication of CNTs / SiO2 composites with high electrochemical performance. x / Ti3C2T x A composite anode material was developed and applied in the field of silicon-carbon anode technology for high-density lithium-ion batteries. The intercalation product PDMS-CoCl2-Ti3C2T was constructed by synergistic intercalation of PDMS (which functions as both an intercalating agent and a solvent) and CoCl2 with MXene. x Based on the in-situ synergistic growth mechanism, PDMS pyrolyzes to generate SiO at 700℃ in an Ar / H2 atmosphere. x Simultaneously, CoCl2 decomposes into metallic Co nanoparticles, catalyzing the growth of CNTs and forming a three-dimensional conductive network, significantly improving the material's conductivity and structural stability. The interlayer confinement effect of MXene effectively buffers SiO₂. xThe volume expansion inhibits electrode pulverization; the permeation network of CNTs enhances electron / ion transport, enabling the composite material to withstand 100 mAg. -1 The initial discharge specific capacity at current density exceeds 650 mAh g. -1 In summary, this invention achieves material structure control and performance optimization through a clever intercalation-pyrolysis synergistic strategy, demonstrating significant originality and application value.

[0121] The embodiments described herein cover any points not exhaustively within the scope of the technical claims of this invention, as well as new technical solutions formed by equivalent substitutions of one or more technical features in the embodiments. These are all within the scope of the claims of this invention. Furthermore, in all listed or unlisted embodiments of this invention, each parameter in the same embodiment merely represents an instance (i.e., a feasible solution) of its technical solution, and there is no strict coordination or limitation relationship between the parameters. The parameters can be substituted for each other without violating axioms and the claims of this invention, unless otherwise stated.

[0122] The technical means disclosed in this invention are not limited to those described above, but also include technical solutions composed of any combination of the above technical features. The above descriptions are specific embodiments of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

[0123] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for in-situ synergistic growth of CNTs / SiO2 with co-intercalated MXene x Composite material, characterized in that, The composite material includes a MXene skeleton, a CNTs conductive network, and SiO x Tertiary structure of the active unit.

2. A method for in-situ synergistic growth of CNTs / SiO2 with co-intercalated MXene as described in claim 1 x A method for preparing composite materials, characterized in that, The method includes the following steps: S1, Ti3AlC2 is etched in hydrofluoric acid containing LiCl, and after washing, a multilayer Ti3C2T x ; S2, mixing the multi-layer Ti3C2T x and intercalation agent, and the intercalation product is obtained by separation, washing, centrifugation, filtration and drying. S3. The intercalation product is subjected to high-temperature annealing to obtain co-intercalated MXene in-situ synergistic growth of CNTs / SiO x Composite materials.

3. The in-situ synergistic growth of CNTs / SiO2 with co-intercalation MXene as described in claim 2 x A method for preparing composite materials, characterized in that, In step S1, the concentration of hydrofluoric acid is 1-20 mol / mL, and the amount of LiCl added is 0.001-1.2 g / mL.

4. The in-situ synergistic growth of CNTs / SiO2 with co-intercalation MXene as described in claim 2 x A method for preparing composite materials, characterized in that, In step S1, the mass ratio of Ti3AlC2 to LiCl is 1:(0.1-30).

5. The in-situ synergistic growth of CNTs / SiO2 with co-intercalated MXene as described in claim 2 x A method for preparing composite materials, characterized in that, In step S2, the intercalating agent is a functionalized organosilicon polymer and a metal catalyst in a mass ratio of (2-20):(0.005-0.5).

6. The in-situ co-grown CNTs / SiO2 method of co-intercalated MXene as described in claim 5 x A method for preparing composite materials, characterized in that, The functionalized organosilicon polymer is one of poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane] and poly(dimethylsiloxane), bis(3-aminopropyl)-terminated; And / or metal catalysts include at least one of cobalt chloride, ferric chloride, and nickel chloride.

7. The in-situ synergistic growth of CNTs / SiO2 with co-intercalated MXene as described in claim 2 x A method for preparing composite materials, characterized in that, In step S2, multilayer Ti3C2T x The mass ratio of the intercalating agent to the intercalating agent is (0.3-0.5):(1.5-21).

8. The in-situ co-grown CNTs / SiO2 method of co-intercalated MXene as described in claim 2 x A method for preparing composite materials, characterized in that, In step S3, high-temperature annealing is carried out in an Ar and H2 atmosphere; and it is divided into two stages. First stage annealing: Heat to 200-600℃ at a rate of 1-20℃ / min, and hold for 10-120min; Second stage annealing: Increase the temperature to 400-800℃ at a rate of 5-20℃ / min, and hold for 60-480min.

9. The in-situ synergistic growth of CNTs / SiO2 with co-intercalation MXene as described in claim 8 x A method for preparing composite materials, characterized in that, First stage annealing: Ar flow rate 100-500 sccm, H2 flow rate 10-100 sccm; Second stage annealing: Ar flow rate is 10-200 sccm, H2 flow rate is 10-100 sccm, and total flow rate is 100-300 sccm.

10. A high-energy-density lithium-ion battery anode material, characterized in that, The negative electrode material includes the composite material of claim 1 or the composite material prepared by the method of any one of claims 2-9.

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