Preparation of a C3N5 / MXene composite material and its application in aqueous zinc-ion batteries

Abstract

This invention discloses the preparation of a C3N5 / MXene composite material and its application in an aqueous zinc-ion battery. The preparation method of the C3N5 / MXene composite material includes the following steps: 3-amino-1,2,4-triazole is used as a raw material, which undergoes calcination and hydrothermal reaction, followed by washing and drying to obtain C3N5 powder; lithium fluoride is added to hydrochloric acid, stirred evenly, and then Ti3AlC2 is added, with continuous stirring and etching. After centrifugation and washing, deionized water is added again, and the mixture is sonicated under a protective atmosphere. The supernatant is collected by centrifugation to obtain a monolayer MXene dispersion; the C3N5 powder is added to deionized water and dispersed evenly to obtain a C3N5 dispersion; then, the monolayer MXene dispersion is added to the C3N5 dispersion. After the reaction is complete, the precipitate is collected by centrifugation and dried to obtain the C3N5 / MXene composite material. The C3N5 / MXene composite material prepared by this invention, as the negative electrode of an aqueous zinc-ion battery, can overcome the problems of dendrite growth and hydrogen evolution reaction existing in traditional zinc negative electrodes, significantly improving the electrochemical performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of zinc-ion battery technology, and in particular to the preparation of a C3N5 / MXene composite material and its application in aqueous zinc-ion batteries. Background Technology

[0002] Aqueous zinc-ion batteries are a type of battery that utilizes zinc ions (Zn) 2+ Aqueous zinc-ion batteries are battery systems that store and convert energy by inserting and de-electroding zinc ions between positive and negative electrodes. These batteries typically use zinc as the negative electrode due to its high theoretical capacity (820 mAh / g), good safety, and low cost. The electrolyte is generally an aqueous solution containing zinc salts, while the positive electrode material can be a variety of compounds capable of inserting and releasing zinc ions, such as manganese oxides and vanadium-based compounds. Aqueous zinc-ion batteries have attracted widespread attention due to their high safety, environmental friendliness, and low cost. They typically use zinc as the negative electrode material. However, zinc is prone to dendrite formation during electrochemical deposition and stripping in aqueous solutions, and hydrogen evolution reactions may occur. These problems lead to a significant decrease in the battery's cycle stability and coulombic efficiency.

[0003] In aqueous zinc-ion batteries, the choice of anode material is crucial because it directly affects battery performance, including energy density, cycle stability, and safety. To address the aforementioned drawbacks of zinc anodes, the following methods can be employed to improve their performance, for example:

[0004] (1) Surface modification: By adding a protective layer or chemically modifying the surface of the zinc anode, the Zn content can be adjusted. 2+ The deposition behavior promotes uniform deposition and inhibits dendrite growth.

[0005] (2) Electrolyte optimization: Adjust the electrolyte composition, such as adding specific additives or changing the solvent composition, to reduce the occurrence of side reactions and improve the stability of the zinc anode.

[0006] (3) Develop a new material: Due to the special physicochemical properties of the new material, such as good thermal stability, chemical stability and abundant active sites, it shows the potential to capture Zn 2+ This capability is expected to be used to improve the performance of zinc anodes.

[0007] With the deepening research on zinc anode modification methods and the exploration of new material applications, the performance of aqueous zinc-ion batteries will be further improved, thereby expanding their application prospects in the energy storage field. However, the development of new materials has problems such as high cost, low stability and lifespan, low safety, and poor compatibility, which prevent them from being truly used in actual production. Chinese patent CN111864193A discloses a heteroatom-modified hollow microcarbon sphere. A polymer precursor and a metal salt are added to a micron-sized spherical carbonitride solution for surface coating reaction to obtain a precursor for microcarbon spheres. The micron-sized spherical carbonitride is at least one of g-C3N4, C3N3, and C3N5. The obtained microcarbon sphere precursor is heat-treated in an inert atmosphere to obtain heteroatom-modified hollow microcarbon spheres. The product can be used as a cathode material for lithium-sulfur batteries. Chinese patent CN113937264A discloses a method for preparing carbonitride-modified manganese vanadate at room temperature. The method involves mixing carbonitride and manganese vanadate nanoparticles in 20 mL of ethanol solution, thoroughly mixing using ultrasound, and then vacuum drying in a vacuum drying oven to obtain a core-shell composite cathode material of carbonitride@Mn2V2O7. This composite cathode material can be used in aqueous zinc-ion batteries. The aforementioned carbonitride C3N5 has advantages such as simple preparation method, high stability, and multiple active sites; however, it is primarily used in cathode materials for batteries, and its application in anode materials for aqueous zinc-ion batteries is currently limited. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing C3N5 / MXene composite material and its application in aqueous zinc-ion batteries, in order to solve the problem that the negative electrode material in the above-mentioned aqueous zinc-ion batteries is only Zn negative electrode, and Zn negative electrode has disadvantages such as dendrite growth and hydrogen evolution reaction, which lead to the decline of battery performance.

[0009] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a C3N5 / MXene composite material, comprising the following steps:

[0010] (1) Preparation of C3N5

[0011] C3N5 powder was obtained by calcining and hydrothermal reaction of 3-amino-1,2,4-triazole as raw material, followed by washing and drying.

[0012] (2) Preparation of single-layer few-layer MXene dispersion

[0013] Lithium fluoride was added to hydrochloric acid and stirred until homogeneous. Ti3AlC2 was then added, and the mixture was stirred and etched continuously. After centrifugation and washing, deionized water was added again, and the mixture was sonicated under a protective atmosphere. The supernatant was collected by centrifugation to obtain a single-layer MXene dispersion.

[0014] (3) Preparation of C3N5 / MXene composite material

[0015] C3N5 powder was added to deionized water and dispersed evenly to obtain a C3N5 dispersion. Then, a single-layer MXene dispersion was added to the C3N5 dispersion. After the reaction was completed, the precipitate was collected by centrifugation and dried to obtain a C3N5 / MXene composite material.

[0016] Preferably, in step (1), the calcination temperature is 500~600℃ and the time is 2~4h.

[0017] Preferably, in step (1), after calcination, intermediate powder is ground and collected, sodium hydroxide solution is added to the intermediate powder to obtain a mixture, the mixture is transferred to a reaction vessel and hydrothermally reacted at 100~150℃ for 10~15h, and C3N5 powder is obtained after washing and drying.

[0018] Preferably, in step (2), the mass-to-volume ratio of lithium fluoride to hydrochloric acid is 1.5~1.8g:15~25mL; the mass ratio of lithium fluoride to Ti3AlC2 is 1.5~1.8g:1g.

[0019] Preferably, in step (2), lithium fluoride is added to hydrochloric acid, stirred for 8-15 min, and then Ti3AlC2 is added. The mixture is stirred for 20-25 h for etching. The mixture is centrifuged and washed multiple times until the pH is 4.5-5.5. Deionized water is added again, and the mixture is sonicated for 1-3 h under a protective gas. The supernatant is collected by centrifugation at 3000-4000 r / min for 0.5-1.5 h to obtain a single-layer MXene dispersion.

[0020] Preferably, in step (2), the concentration of the monolayer MXene dispersion is 3~8 mg·mL. -1 .

[0021] Preferably, in step (3), the mass-to-volume ratio of C3N5 powder to monolayer MXene dispersion is 0.1~0.3g:10mL.

[0022] A second aspect of the present invention provides a C3N5 / MXene composite material, which is prepared by the above-described preparation method.

[0023] Preferably, when MXene is added to C3N5, C3N5 will grow on the MXene surface to form a smooth, large-sized nanosheet layer.

[0024] A third aspect of the present invention provides an application of C3N5 / MXene composite material in aqueous zinc-ion batteries.

[0025] Preferably, the C3N5 / MXene composite material is used as the negative electrode in an aqueous zinc-ion battery, wherein the specific preparation process of the negative electrode is as follows:

[0026] The C3N5 / MXene composite material, binder and solvent are mixed and stirred to obtain a slurry. The slurry is then coated on the surface of zinc foil or titanium foil, dried and cut to obtain a C3N5 / MXene@Zn electrode or a C3N5 / MXene@Ti electrode. The C3N5 / MXene@Zn electrode or the C3N5 / MXene@Ti electrode is the negative electrode in an aqueous zinc-ion battery.

[0027] Therefore, the preparation of a C3N5 / MXene composite material with the above-mentioned structure and its application in an aqueous zinc-ion battery, as described in this invention, have the following beneficial effects:

[0028] This invention combines C3N5 and Mxene to form a novel anode material, which is then applied to aqueous zinc-ion batteries. Compared with traditional zinc anodes, this novel anode material has advantages such as high conductivity, faster reaction kinetics, and high stability, providing a new approach for the research and development of anode materials for aqueous zinc-ion batteries.

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0030] Figure 1 XRD patterns of C3N5 and C3N5 / MXene;

[0031] Figure 2 The images are SEM images, where (a) is a SEM image of C3N5; and (b) is a SEM image of C3N5 / MXene.

[0032] Figure 3 EIS curves for C3N5 / MXene@Zn and Zn symmetric cells;

[0033] Figure 4 For C3N5 / MXene@Zn and Zn symmetric cells at 1 mA·cm -2 Nucleation overpotential at current density;

[0034] Figure 5 The capacity of C3N5 / MXene@Zn and Zn symmetric cells at different current densities is 1 mAh•cm³. -2 The results of the rate performance test;

[0035] Figure 6 CV curves for Zn||C3N5 / MXene@Ti and Zn||Ti asymmetric cells;

[0036] Figure 7 For C3N5 / MXene@Zn and Zn symmetric cells at (a) 0.2 mA•cm -2and (b) 5mA•cm -2 Cyclic performance test results at current density;

[0037] Figure 8 C3N5 / MXene@Zn||H6V4O 10 / MXene and Zn||H6V4O 10 Cycle performance of MXene batteries. Detailed Implementation

[0038] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the present invention is not limited to this embodiment.

[0039] Example 1

[0040] A method for preparing a C3N5 / MXene composite material includes the following steps:

[0041] (1) Preparation of C3N5

[0042] Weigh 2g of 3-amino1,2,4-triazole (3AT), calcine at 550℃ for 3h, grind and collect the intermediate powder, add the intermediate powder to 80mL of 0.9mol / L NaOH solution to obtain a mixture, transfer the stirred mixture to a reaction vessel, keep it at 120℃ for 12h for hydrothermal reaction, wash and dry to obtain C3N5 powder.

[0043] (2) Preparation of single-layer few-layer MXene dispersion

[0044] First, 1.6000 g of lithium fluoride was added to 20 mL of 2 mol / L hydrochloric acid and stirred for 10 min in an ice-water bath to obtain a mixed solution. Then, 1.0000 g of Ti3AlC2 was weighed and slowly poured into the mixed solution, and the mixture was stirred and etched for 24 h. The solution was then centrifuged and washed multiple times until the pH reached 5. After discarding the supernatant, 30 mL of deionized water was added, and argon gas was introduced as a protective gas. The mixture was then sonicated for 2 h. Finally, the solution was heated to 3500 rpm. -1 Centrifuge for 1 hour under the specified conditions and collect the supernatant to obtain a monolayer few-layer MXene dispersion (containing a monolayer few-layer Ti3C2T). x (solution) containing a single or few layers of Ti3C2T x The concentration of the solution is 5 mg / mL. -1 .

[0045] (3) Preparation of C3N5 / MXene composite material

[0046] 0.2 g of C3N5 powder was added to 80 mL of deionized water and dispersed evenly to obtain a C3N5 dispersion. Then, 10 mL of monolayer MXene dispersion was added to the C3N5 dispersion. After the reaction was completed, the precipitate was collected by centrifugation and dried to obtain the C3N5 / MXene composite material.

[0047] Example 2

[0048] The C3N5 / MXene composite material prepared in Example 1 was characterized by XRD and SEM.

[0049] Figure 1 The XRD patterns of C3N5 and C3N5 / MXene are shown below. Figure 1 As can be seen, C3N5 exhibits a distinct diffraction peak at 27.6°, corresponding to the (002) crystal plane, proving that C3N5 was successfully prepared. After being combined with MXene, the C3N5 / MXene composite material shows strong diffraction peaks at 7.6°, 16.4°, and 60.5°, corresponding to the (002), (006), and (110) crystal planes of MXene. Furthermore, a diffraction peak belonging to C3N5 still appears at 27.6°, proving that C3N5 and MXene were successfully combined.

[0050] Figure 2 SEM images of C3N5 and C3N5 / MXene, from Figure 2 As can be seen, when MXene is added to C3N5, C3N5 will grow on the MXene surface to form smooth, large-sized nanosheets.

[0051] Example 3

[0052] The electrochemical properties of the C3N5 / MXene composite material prepared in Example 1 were characterized.

[0053] The testing process is as follows:

[0054] (1) Preparation method of C3N5 / MXene@Zn electrode:

[0055] 0.1000 g of C3N5 / MXene powder was weighed and mixed with PVDF binder at a mass ratio of 9:1 in 0.35 mL of NMP solution for 2 h to obtain a uniform slurry. The slurry was then uniformly coated onto an 80 μm thick zinc foil using a doctor blade to a thickness of 20 μm. The coated zinc foil was placed in a vacuum oven and dried at 60 °C for 12 h. Finally, the dried zinc foil was cut into 12 mm diameter discs to obtain the C3N5 / MXene@Zn electrode.

[0056] (2) Preparation method of C3N5 / MXene@Ti electrode:

[0057] The preparation method of C3N5 / MXene@Ti electrode is the same as that of C3N5 / MXene@Zn electrode. The only difference is that the mixed slurry is uniformly coated on the surface of a 20μm thick titanium foil, then dried at 60℃, and cut into 12mm round pieces to obtain C3N5 / MXene@Ti electrode.

[0058] (4) H6V4O 10 Preparation method of / Mxene@Ti electrode:

[0059] First, 1 g of vanadium pentoxide and 0.9684 g of ascorbic acid were dissolved in 40 mL of deionized water and stirred vigorously at 25 °C for 4 h to form a dark green homogeneous solution. Then, 8 mL of a monolayer Mxene dispersion was added to this homogeneous solution, followed by hydrothermal treatment at 180 °C for 24 h. After repeated washing with deionized water and ethanol, the powder was collected and dried to obtain H6V4O. 10 / MXene powder.

[0060] H6V4O 10 Mxene powder, acetylene black, and PVDF binder were weighed at a mass ratio of 7:2:1. PVDF was dissolved in N-methylpyrrolidone (NMP) solution at a concentration of 3% beforehand, and the mixture was stirred thoroughly to obtain a slurry. The slurry was then poured onto a 10 μm thick titanium foil and coated with a 20 μm thick layer using an automatic coating machine. The coated titanium foil was dried at 60°C for 12 hours and then cut into 12 mm diameter discs to obtain H6V4O. 10 / Mxene@Ti electrode.

[0061] (4) The preparation method of Zn electrode is as follows:

[0062] A 100μm thick zinc foil is cut into a 12mm diameter disc to obtain a Zn electrode.

[0063] (5) The manufacturing process of button cells is as follows:

[0064] The battery casing uses a CR2032 button cell, with cut electrode sheets serving as the positive and negative electrodes, 2 mol·L⁻¹ -1 A zinc trifluoromethanesulfonate aqueous solution was used as the electrolyte, and glass fiber was used as the diaphragm.

[0065] Figure 3The EIS curves for the C3N5 / MXene@Zn symmetric cells (C3N5 / MXene@Zn||C3N5 / MXene@Zn) are shown, where the Zn||Zn symmetric cell exhibits a charge transfer resistance of 495 Ω. However, when a C3N5 / MXene coating is applied to the Zn surface, the assembled symmetric cell exhibits an extremely low charge transfer resistance of only 47 Ω. This is mainly due to the high zinc affinity and high conductivity of the protective layer, which promotes charge transfer on the negative electrode surface and improves the nucleation kinetics of Zn deposition.

[0066] Figure 4 For C3N5 / MXene@Zn symmetric cells (C3N5 / MXene@Zn||C3N5 / MXene@Zn) and Zn symmetric cells (Zn||Zn) at 1 mA·cm -2 Nucleation overpotential at current density, from Figure 4 As can be seen, the nucleation overpotential of the Zn||Zn symmetric cell is 119mV, which is much higher than the nucleation overpotential of the C3N5 / MXene@Zn anode (45mV). This indicates that Zn 2+ The C3N5 / MXene surface exhibits a lower nucleation energy barrier, i.e., Zn 2+ It tends to nucleate on the C3N5 / MXene surface, eventually inducing uniform Zn deposition.

[0067] Figure 5 The capacity of C3N5 / MXene@Zn symmetric cells and Zn symmetric cells at different current densities is 1 mAh•cm. -2 The rate performance test results, from Figure 5 As can be seen from this, as the current density increases from 0.2 mA·cm⁻¹ -2 Gradually increase to 5mA·cm -2 The polarization voltage of Zn gradually increases. However, compared to Zn symmetric cells, C3N5 / MXene@Zn symmetric cells exhibit lower polarization voltages at each current density, indicating that the modified C3N5 / MXene@Zn anode has better rate performance. Particularly noteworthy is the performance at 5 mA·cm⁻¹. -2 At high current densities, the polarization voltage of a Zn symmetric cell is 274 mV, while that of a C3N5 / MXene@Zn symmetric cell is only 118 mV, indicating that the C3N5 / MXene coating can effectively enhance the polarization voltage of Zn. 2+ Dynamics of the deposition process.

[0068] Figure 6 The CV curves of Zn||C3N5 / MXene@Ti and Zn||Ti asymmetric cells are shown from... Figure 6As can be seen, under the same voltage window, the C3N5 / MXene@Ti electrode exhibits stronger redox peak intensity and larger CV peak area, indicating that the C3N5 / MXene surface is enriched with more nucleation sites and has faster reaction kinetics.

[0069] Figure 7 For C3N5 / MXene@Zn and Zn symmetric cells at (a) 0.2 mA•cm -2 and (b) 5mA•cm -2 Cyclic performance test results at current density, from Figure 7 As can be seen, the C3N5 / MXene@Zn symmetric cell exhibits highly stable zinc deposition / stripping performance, with the polarization voltage remaining within a stable range after 500 hours of cycling. The C3N5 / MXene@Zn symmetric cell also demonstrates excellent cycle stability, exhibiting only a slight open circuit after 200 hours of cycling; after the open circuit recovered, the polarization voltage remained within a stable range.

[0070] Figure 8 C3N5 / MXene@Zn||H6V4O 10 / MXene and Zn||H6V4O 10 The cycle performance of MXene batteries, from Figure 8 As can be seen from this, C3N5 / MXene@Zn||H6V4O 10 The capacity of the MXene battery still showed an increasing trend in the early stages of charging and discharging, proving that H+ would still slowly form on the surface of the positive electrode. x V₂O₅ amorphous phase layer. When the battery is at 1 A·g -1 After undergoing 2000 charge-discharge cycles at a current density, it still maintained 150.8 mAh·g. -1 Its discharge specific capacity and 60.0% capacity retention are higher than those of Zn||H6V4O. 10 The C3N5 / MXene battery demonstrates that the C3N5 / MXene anode coating can effectively prevent dendrite growth and suppress side reactions on the anode side, thereby improving the cycle stability of the battery.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. The application of a C3N5 / MXene composite material in the anode material of an aqueous zinc-ion battery, characterized in that: In the C3N5 / MXene composite material, C3N5 grows on the MXene surface to form smooth, large-sized nanosheets. The preparation method of C3N5 / MXene composite material includes the following steps: (1) Preparation of C3N5 C3N5 powder was obtained by calcining and hydrothermal reaction of 3-amino-1,2,4-triazole as raw material, followed by washing and drying. (2) Preparation of single-layer few-layer MXene dispersion Lithium fluoride was added to hydrochloric acid and stirred until homogeneous. Ti3AlC2 was then added, and the mixture was stirred and etched continuously. After centrifugation and washing, deionized water was added again, and the mixture was sonicated under a protective atmosphere. The supernatant was collected by centrifugation to obtain a single-layer MXene dispersion. (3) Preparation of C3N5 / MXene composite material C3N5 powder was added to deionized water and dispersed evenly to obtain a C3N5 dispersion. Then, a monolayer MXene dispersion was added to the C3N5 dispersion. The mass-volume ratio of C3N5 powder to monolayer MXene dispersion was 0.1 ~ 0.3 g: 10 mL. After the reaction was completed, the precipitate was collected by centrifugation and dried to obtain the C3N5 / MXene composite material.

2. The application according to claim 1, characterized in that: In step (1), the calcination temperature is 500 ~ 600℃ and the time is 2 ~ 4h.

3. The application according to claim 1, characterized in that: In step (1), after calcination, the intermediate powder is ground and collected. Sodium hydroxide solution is added to the intermediate powder to obtain a mixture. The mixture is transferred to a reaction vessel and hydrothermally reacted at 100-150℃ for 10-15 hours. After washing and drying, C3N5 powder is obtained.

4. The application according to claim 1, characterized in that: In step (2), the mass-to-volume ratio of lithium fluoride to hydrochloric acid is 1.5 ~ 1.8 g: 15 ~ 25 mL; the mass ratio of lithium fluoride to Ti3AlC2 is 1.5 ~ 1.8 g: 1 g.

5. The application according to claim 1, characterized in that: In step (2), lithium fluoride is added to hydrochloric acid and stirred for 8-15 min. Ti3AlC2 is then added and stirred for 20-25 h for etching. The mixture is centrifuged and washed multiple times until the pH is 4.5-5.

5. Deionized water is added again and the mixture is sonicated for 1-3 h under a protective atmosphere. The supernatant is collected by centrifugation at 3000-4000 r / min for 0.5-1.5 h to obtain a single-layer MXene dispersion.

6. The application according to claim 1, characterized in that: In step (2), the concentration of the monolayer MXene dispersion is 3~8 mg·mL. -1 .

7. The application according to claim 1, characterized in that: The C3N5 / MXene composite material is used as the negative electrode in an aqueous zinc-ion battery. The specific preparation process of the negative electrode is as follows: The C3N5 / MXene composite material, binder and solvent are mixed and stirred to obtain a slurry. The slurry is then coated on the surface of zinc foil or titanium foil, dried and cut to obtain a C3N5 / MXene@Zn electrode or a C3N5 / MXene@Ti electrode. The C3N5 / MXene@Zn electrode or the C3N5 / MXene@Ti electrode is the negative electrode in an aqueous zinc-ion battery.

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