Preparation method and application of MXene-Bi ultra-small nanoparticle composite gel electrode material

Abstract

This invention provides a method for preparing and applying MXene-Bi ultra-small nanoparticle composite gel electrode materials. The method includes: etching, cleaning, peeling, and centrifuging an MXene precursor to obtain a few-layer MXene aqueous dispersion; reacting the MXene aqueous dispersion with Bi... 3+ After mixing the salts, MXene-Bi was obtained. 3+ Gel; MXene-Bi 3+ The gel is reacted with a reducing agent and then freeze-dried to obtain an MXene-Bi ultra-small nanoparticle composite gel. The ultra-small Bi nanoparticles in the MXene-Bi ultra-small nanoparticle composite gel electrode structure prepared in this invention can alleviate the aggregation between MXene sheets. The MXene gel channels not only provide three-dimensional electron transport channels but also suppress volume expansion during the Bi conversion reaction. The MXene-Bi ultra-small nanoparticle composite gel can be applied to electrode materials in the fields of capacitor deionization, batteries, and electroadsorption.

Description

Technical Field

[0001] This invention relates to the field of electrochemical electrode material synthesis technology, and in particular to a method for preparing an MXene-Bi ultra-small nanoparticle composite gel electrode material, as well as the MXene-Bi ultra-small nanoparticle composite gel electrode material prepared by this method and its applications. Background Technology

[0002] Electrode materials are key factors determining the deionization, battery, and electroadsorption performance of capacitors. Bi (Bi) metal is inexpensive and possesses advantages such as high theoretical capacity and excellent chemical stability. However, the reaction between Bi and chloride ions is mainly diffusion-controlled, resulting in poor conductivity. Furthermore, the generated Bi oxychloride undergoes significant volume expansion (approximately 158%), leading to unsatisfactory chloride ion capture performance and poor cycle stability in Bi-based electrodes. This severely impacts their practical application value. Size control can mitigate the impact of volume expansion on electrode cycle stability, and compositing with conductive materials can significantly improve the conductivity of Bi-based electrodes. These are effective strategies for enhancing the performance of Bi-based electrodes and promoting their industrialization. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the present invention provides the following technical solution:

[0004] On the one hand, a method for preparing an MXene-Bi ultrasmall nanoparticle composite gel electrode material is provided, the method comprising the following steps:

[0005] S1 and MXene precursors were etched, cleaned, peeled, and centrifuged to obtain an MXene aqueous dispersion;

[0006] S2, MXene aqueous dispersion and Bi 3+ After mixing the salts, MXene-Bi was obtained. 3+ gel;

[0007] S3, MXene-Bi 3+ The gel was reacted with a reducing agent and then freeze-dried to obtain an MXene-Bi ultra-small nanoparticle composite gel.

[0008] In another embodiment of the present invention, in step S1, the MXene is one of the following compounds:

[0009] Ti3C2T x Nb2CT x V4C3T x Ti2CT x or Mo2CT x .

[0010] In another embodiment of the present invention, in step S1, after obtaining the MXene aqueous dispersion, the MXene aqueous dispersion is intercalated with ethanol or sodium hydroxide, and then ultrasonically exfoliated.

[0011] In another embodiment of the invention, the conditions for ultrasonic ablation are as follows:

[0012] Power greater than 800W, time greater than 3h, and circulating water is required to cool the MXene aqueous dispersion during ultrasonication.

[0013] In another embodiment of the present invention, in step S1, the centrifugation speed is greater than 8000 rpm, and the supernatant after centrifugation is the MXene aqueous dispersion.

[0014] In another embodiment of the present invention, in step S2, the concentration of the MXene aqueous dispersion should be 5 mg / mL-15 mg / mL and the volume should be 1 mL-10 mL.

[0015] In another embodiment of the present invention, in step S2, the Bi 3+ The salt is one of the following bromide salts:

[0016] Bi(NO3)3, BiCl3 or Bi(CH3COO)3.

[0017] In another embodiment of the present invention, in step S2, the Bi 3+ The salt concentration is 0.1 mol / L-5 mol / L and the volume is 100 μL-500 μL.

[0018] In another embodiment of the present invention, in step S2, after obtaining the MXene-Bi 3+ After gelation, the MXene-Bi 3+ The gel was soaked in deionized water to wash away excess Bi. 3+ The soaking process should be repeated at least once.

[0019] In another embodiment of the present invention, in step S3, the reducing agent is one of the following reducing agents:

[0020] NaBH4, KBH4, C6H8O6, C6H8O6Na, N2H4·H2O or Na2S2O3.

[0021] In another embodiment of the present invention, in step S3, the concentration of the reducing agent is 0.5 mol / L-5 mol / L, the reduction temperature is 25℃-90℃, and the reduction time is 0.5h-6h.

[0022] On the other hand, an MXene-Bi ultra-small nanoparticle composite gel electrode material is provided, which is prepared based on the above-described preparation method of the MXene-Bi ultra-small nanoparticle composite gel electrode material.

[0023] On the other hand, the application of the MXene-Bi ultra-small nanoparticle composite gel electrode material described above, or the MXene-Bi ultra-small nanoparticle composite gel electrode material prepared based on the above preparation method, in capacitor deionization, batteries, or electroadsorption is provided.

[0024] The beneficial effects of the technical solutions provided by the embodiments of the present invention include at least the following:

[0025] This invention obtains a few-layer MXene aqueous dispersion by etching, cleaning, peeling, and centrifugation of an MXene precursor; the MXene aqueous dispersion is then mixed with Bi... 3+ After mixing the salts, MXene-Bi was obtained. 3+ Gel; MXene-Bi 3+ The gel is reacted with a reducing agent and then freeze-dried to obtain an MXene-Bi ultra-small nanoparticle composite gel. The ultra-small Bi nanoparticles in the MXene-Bi ultra-small nanoparticle composite gel electrode structure prepared in this invention can alleviate the aggregation between MXene sheets. The MXene gel channels not only provide three-dimensional electron transport channels but also suppress volume expansion during the Bi conversion reaction. The MXene-Bi ultra-small nanoparticle composite gel can be applied to electrode materials in the fields of capacitor deionization, batteries, and electroadsorption.

[0026] Furthermore, the present invention utilizes Bi 3+ Disrupting the electrostatic balance between MXene nanosheets allows MXene to separate from the solution and initiates rapid gelation, followed by the reaction of Bi... 3+ In-situ reduction was performed to construct a three-dimensional MXene-Bi nanoparticle gel network. Bi nanoparticles inhibited the aggregation of MXene nanosheets, exposing more active sites. The MXene gel network coupled with small-sized Bi nanoparticles effectively mitigated volume expansion during the Bi reaction. The MXene-Bi ultra-small nanoparticle composite gel electrode obtained by this method exhibits excellent performance, characterized by abundant active sites, fast electron transport, and strong cycling stability. Furthermore, the process is simple and easy to implement, suitable for large-scale production, and can be applied to electrode materials in capacitor deionization, batteries, and electroadsorption fields. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a transmission electron microscope image of an MXene-Bi ultra-small nanoparticle composite gel electrode material provided in an embodiment of the present invention (a, b, and c in the figure correspond to the three embodiments of the present invention, respectively);

[0029] Figure 2 This is a schematic diagram comparing the impedance spectra and equivalent circuit models of an MXene-Bi ultra-small nanoparticle composite gel electrode material provided in this embodiment of the invention with those of pure MXene and pure Bi nanoparticles.

[0030] Figure 3 This is a schematic diagram comparing the specific capacitance of an MXene-Bi ultra-small nanoparticle composite gel electrode material provided in an embodiment of the present invention with that of pure MXene and pure Bi nanoparticles. Detailed Implementation

[0031] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0032] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0033] In the embodiments of this invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, their intended meanings are consistent. Similarly, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, their intended meanings are consistent.

[0034] In this embodiment of the invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0035] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0036] In this embodiment, the preparation materials and equipment can be provided by the laboratory or purchased by the user from the market.

[0037] The following embodiments are further illustrations of the present invention, but are not intended to limit the scope of the invention.

[0038] Example 1:

[0039] The preparation method of the MXene-Bi ultrasmall nanoparticle composite gel electrode material in this embodiment includes the following steps:

[0040] (1) Weigh 1g of lithium fluoride and 40ml of 9mol / L hydrochloric acid into a polytetrafluoroethylene beaker (100mL volume) and stir for 60min at a speed of 500rpm.

[0041] (2) Slowly add 1g Ti3AlC2 to the beaker in the first step, adjust the reaction temperature to 35 degrees, and stir continuously for 48 hours.

[0042] (3) The Ti3C2T obtained in (2) x The product was centrifuged with deionized water (3500 rpm, 5 min) and the lower precipitate was removed. This step was repeated until pH > 5.

[0043] (4) Disperse the product obtained in (3) with deionized water, add an appropriate amount of ethanol, sonicate for 3 hours under N2 atmosphere and circulating cooling water protection, centrifuge (8000 rpm, 2 min) and take the supernatant. Take 1 mL of the supernatant and dry it to determine its concentration.

[0044] (5) Dilute the supernatant obtained in (4) to 10 mg / mL, take 5 mL of the supernatant, and add 200 μL of 1 mol / L solution. -1 When a Bi(NO3)3·5H2O solution is added, the mixed solution rapidly transforms into MXene-Bi within minutes. 3+ Hydrogel.

[0045] (6) Soak the hydrogel obtained in (5) in deionized water multiple times to wash away excess metal ions.

[0046] (7) Transfer the hydrogel obtained in (6) to a beaker and add 40 mL of 0.5 mol / L NaBH4 solution. Place the beaker in a 40°C water bath and heat for 3 hours to remove Bi. 3+ It is reduced to metallic Bi nanoparticles.

[0047] (8) After washing the product of (7) with deionized water multiple times, it was placed in a refrigerator for pre-freezing for 24 hours, and then transferred to a freeze dryer to remove moisture (12 hours) to obtain MXene-Bi ultra-small nanoparticle composite gel electrode material.

[0048] Example 2:

[0049] The preparation method of the MXene-Bi ultrasmall nanoparticle composite gel electrode material in this embodiment includes the following steps:

[0050] (1) Weigh 1g of lithium fluoride and 40ml of 9mol / L hydrochloric acid into a polytetrafluoroethylene beaker (100mL volume) and stir for 60min at a speed of 500rpm.

[0051] (2) Slowly add 1g Ti3AlC2 to the beaker in the first step, adjust the reaction temperature to 35 degrees, and stir continuously for 48 hours.

[0052] (3) The Ti3C2T obtained in (2) x The product was centrifuged with deionized water (3500 rpm, 5 min) and the lower precipitate was removed. This step was repeated until pH > 5.

[0053] (4) Disperse the product obtained in (3) with deionized water, add an appropriate amount of ethanol, sonicate for 3 hours under N2 atmosphere and circulating cooling water protection, centrifuge (8000 rpm, 2 min) and take the supernatant. Take 1 mL of the supernatant and dry it to determine its concentration.

[0054] (5) Dilute the supernatant obtained in (4) to 10 mg / mL, take 5 mL of the supernatant, and add 400 μL of 1 mol / L solution. -1 When a Bi(NO3)3·5H2O solution is added, the mixed solution rapidly transforms into MXene-Bi within minutes. 3+ Hydrogel.

[0055] (6) Soak the hydrogel obtained in (5) in deionized water multiple times to wash away excess metal ions.

[0056] (7) Transfer the hydrogel obtained in (6) to a beaker and add 40 mL of 0.5 mol / L NaBH4 solution. Place the beaker in a 40°C water bath and heat for 3 hours to remove Bi. 3+ It is reduced to metallic Bi nanoparticles.

[0057] (8) After washing the product of (7) with deionized water multiple times, it was placed in a refrigerator for pre-freezing for 24 hours, and then transferred to a freeze dryer to remove moisture (12 hours) to obtain MXene-Bi ultra-small nanoparticle composite gel electrode material.

[0058] Example 3:

[0059] The preparation method of the MXene-Bi ultrasmall nanoparticle composite gel electrode material in this embodiment includes the following steps:

[0060] (1) Weigh 1g of lithium fluoride and 40ml of 9mol / L hydrochloric acid into a polytetrafluoroethylene beaker (100mL volume) and stir for 60min at a speed of 500rpm.

[0061] (2) Slowly add 1g Ti3AlC2 to the beaker in the first step, adjust the reaction temperature to 35 degrees, and stir continuously for 48 hours.

[0062] (3) The Ti3C2T obtained in (2) x The product was centrifuged with deionized water (3500 rpm, 5 min) and the lower precipitate was removed. This step was repeated until pH > 5.

[0063] (4) Disperse the product obtained in (3) with deionized water, add an appropriate amount of ethanol, sonicate for 3 hours under N2 atmosphere and circulating cooling water protection, centrifuge (8000 rpm, 2 min) and take the supernatant. Take 1 mL of the supernatant and dry it to determine its concentration.

[0064] (5) Dilute the supernatant obtained in (4) to 10 mg / mL, take 5 mL of the supernatant, and add 800 μL of 1 mol / L solution. -1 When a Bi(NO3)3·5H2O solution is added, the mixed solution rapidly transforms into MXene-Bi within minutes. 3+ Hydrogel.

[0065] (6) Soak the hydrogel obtained in (5) in deionized water multiple times to wash away excess metal ions.

[0066] (7) Transfer the hydrogel obtained in (6) to a beaker and add 40 mL of 0.5 mol / L NaBH4 solution. Place the beaker in a 40°C water bath and heat for 3 hours to remove Bi. 3+ It is reduced to metallic Bi nanoparticles.

[0067] (8) After washing the product of (7) with deionized water multiple times, it was placed in a refrigerator for pre-freezing for 24 hours, and then transferred to a freeze dryer to remove moisture (12 hours) to obtain MXene-Bi ultra-small nanoparticle composite gel electrode material.

[0068] like Figure 1As shown in the figure, a and c are transmission electron microscope (TEM) images of the MXene-Bi ultra-small nanoparticle composite gel electrode materials in Examples 1-3 of this invention, respectively. The figures show that the ultra-small Bi nanoparticles are uniformly distributed on the surface of the few-layer MXene sheets, indicating that the Bi nanoparticles can inhibit the aggregation of MXene nanosheets, exposing more active sites. The small size of the Bi nanoparticles is beneficial in mitigating volume expansion during charging and discharging. Furthermore, with the increase in Bi... 3+ As the amount added increases, the size of Bi nanoparticles increases.

[0069] Figure 2 The impedance spectra and equivalent circuit models (Rs is the equivalent resistance, CPE1 is a constant phase angle element 1 (used to simulate a capacitor), and W0 is a specific impedance model used to analyze the impedance characteristics of the system) of the MXene-Bi ultra-small nanoparticle composite gel electrode material (MB-n (n=1, 2, 3)) in Examples 1-3 of this invention, are shown in the figures. As can be seen from the figures, the charge transfer resistance (Rs) of the electrode material can be calculated. ct The resistance values ​​of MXene, Bi, and MB-n (n = 1, 2, 3) were 1.12Ω, 131.7Ω, 3.67Ω, 3.13Ω, and 0.99Ω, respectively. With increasing Bi content, the charge transfer resistance of the MB-n (n = 1, 2, 3) samples decreased, with MB-3 showing the best performance and the lowest charge transfer resistance, which is beneficial for electron transport.

[0070] As attached Figure 3 The figure shows a comparison of the specific capacitance of the MXene-Bi ultra-small nanoparticle composite gel electrode material (MB-n (n=1, 2, 3)) in Examples 1-3 of this invention with that of pure MXene and pure Bi nanoparticles. It can be clearly seen that the specific capacitance of pure MXene is 50.9 mF cm⁻¹. -2 The pure Bi content is 62.2 mF cm⁻¹. -2 With increasing Bi content, the specific capacitance of MB-n (n = 1, 2, 3) gradually increased. Among them, the MB-3 sample exhibited the highest specific capacitance, calculated to be 92.4 mF cm⁻¹. -2 This is because Bi nanoparticles are uniformly embedded between MXene sheets, acting as spacers to prevent MXene sheet aggregation and also forming a three-dimensional porous structure that facilitates ion diffusion, thereby significantly improving the electrochemical performance of the electrode.

[0071] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an MXene-Bi ultrasmall nanoparticle composite gel electrode material, characterized in that, The method includes the following steps: S1 and MXene precursors were etched, cleaned, peeled, and centrifuged to obtain an MXene aqueous dispersion; S2, MXene aqueous dispersion and Bi 3+ After mixing the salts, MXene-Bi was obtained. 3+ gel; S3, MXene-Bi 3+ The gel was reacted with a reducing agent and then freeze-dried to obtain an MXene-Bi ultra-small nanoparticle composite gel.

2. The preparation method of the MXene-Bi ultra-small nanoparticle composite gel electrode material according to claim 1, characterized in that, In step S1, the MXene is one of the following compounds: Ti3C2T x Nb2CT x V4C3T x Ti2CT x or Mo2CT x .

3. The preparation method of the MXene-Bi ultra-small nanoparticle composite gel electrode material according to claim 1, characterized in that, In step S1, after obtaining the MXene aqueous dispersion, the MXene aqueous dispersion is intercalated with ethanol or sodium hydroxide, and then ultrasonically exfoliated.

4. The preparation method of the MXene-Bi ultra-small nanoparticle composite gel electrode material according to claim 3, characterized in that, The conditions for ultrasonic ablation are as follows: Power greater than 800 W, time greater than 3 h, and circulating water is required to cool the MXene aqueous dispersion during ultrasonication.

5. The preparation method of the MXene-Bi ultra-small nanoparticle composite gel electrode material according to claim 1, characterized in that, In step S1, the centrifugation speed is greater than 8000 rpm, and the supernatant after centrifugation is the MXene aqueous dispersion.

6. The preparation method of the MXene-Bi ultra-small nanoparticle composite gel electrode material according to claim 1, characterized in that, In step S2, the concentration of the MXene aqueous dispersion is 5 mg / mL-15 mg / mL and the volume is 1 mL-10 mL.

7. The preparation method of the MXene-Bi ultra-small nanoparticle composite gel electrode material according to claim 1, characterized in that, In step S2, the Bi 3+ The salt is one of the following bromide salts: Bi(NO3)3, BiCl3 or Bi(CH3COO)3.

8. The method for preparing the MXene-Bi ultra-small nanoparticle composite gel electrode material according to claim 1, characterized in that, In step S2, the Bi 3+ The salt concentration ranged from 0.1 mol / L to 5 mol / L, and the volume ranged from 100 µL to 500 µL.

9. The method for preparing the MXene-Bi ultra-small nanoparticle composite gel electrode material according to claim 1, characterized in that, In step S2, after obtaining the MXene-Bi 3+ After gelation, the MXene-Bi 3+ The gel was soaked in deionized water to wash away excess Bi. 3+ The soaking process should be repeated at least once.

10. The method for preparing the MXene-Bi ultrasmall nanoparticle composite gel electrode material according to claim 1, characterized in that, In step S3, the reducing agent is one of the following: NaBH4, KBH4, C6H8O6, C6H8O6Na, N2H4·H2O or Na2S2O3.

11. The method for preparing the MXene-Bi ultrasmall nanoparticle composite gel electrode material according to claim 1, characterized in that, In step S3, the concentration of the reducing agent is 0.5 mol / L-5 mol / L, the reduction temperature is 25℃-90℃, and the reduction time is 0.5 h-6 h.

12. An MXene-Bi ultra-small nanoparticle composite gel electrode material, prepared by the preparation method of the MXene-Bi ultra-small nanoparticle composite gel electrode material according to any one of claims 1-11.

13. The application of the MXene-Bi ultra-small nanoparticle composite gel electrode material according to claim 12 in capacitive deionization, batteries or electroadsorption.

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