Tight hydrophobic zinc powder negative electrode based on electrode reinforcing agent and preparation method thereof

Abstract

The invention discloses a tight hydrophobic zinc powder negative electrode based on an electrode reinforcing agent and a preparation method thereof, relates to the field of zinc ion batteries, and aims to solve the problem of poor long-cycle stability of the zinc powder negative electrode due to insufficient adhesive force and corrosion and hydrogen evolution reaction caused by hydrophilicity of the existing MXene modified zinc powder electrode. Comprising the following steps: (1) weighing zinc powder, adding the zinc powder into a DMDAAC solution, and fully stirring to obtain a mixed solution A; (2) weighing an MXene material, adding deionized water, and carrying out ultrasonic treatment to prepare a colloidal dispersion liquid, so as to obtain a mixed solution B; (3) adding the mixed solution A into the mixed solution B to form a suspension, and violently stirring to generate a precipitate; (4) collecting the precipitate obtained in the step (3), washing and drying to obtain a zinc powder compound D-MXene (at) Zn-p; (5) weighing D-MXene (at) Zn-p, conductive carbon black and polyvinylidene fluoride (PVDF), mixing, adding a solvent, and fully grinding to prepare slurry; and uniformly coating a current collector with the slurry, and drying to obtain the zinc powder composite negative electrode of the aqueous zinc ion battery.

Description

Technical Field

[0001] The invention relates to the technical field of zinc ion batteries, and in particular to a compact hydrophobic zinc powder negative electrode based on an electrode enhancer and a preparation method thereof. Background Art

[0002] Aqueous zinc-ion batteries have received extensive attention and rapid development in the fields of smart cities and large-scale grid energy storage due to the advantages of high theoretical capacity, intrinsic safety and low cost of zinc anodes. Common zinc anodes are mainly zinc foil and zinc powder. Compared with traditional zinc foil anodes, zinc powder anodes have the advantages of adjustable dosage, strong processability and low price, making them an ideal choice for large-scale energy storage applications. However, zinc powder anodes also face some important challenges, including uneven zinc ion deposition, zinc dendrite growth and the occurrence of side reactions (such as hydrogen evolution reaction), which significantly affect the cycle stability of zinc anodes and the overall performance of aqueous zinc-ion batteries. Therefore, it is urgent to develop effective solutions to overcome these problems, improve the performance and service life of aqueous zinc-ion batteries, and promote their commercial application. At present, the main method to improve aqueous zinc powder anodes is through interface modification to improve their reversibility and stability. Among the many modified materials, MXene or carbon materials are widely used in zinc powder modification due to their unique structure, high conductivity and flexibility. MXene materials are conducive to Zn 2+ The uniform deposition and current distribution of MXene can improve the overall performance of zinc powder anode. However, the hydrophilicity of MXene also brings some disadvantages. It enhances the contact between active water in the electrolyte and zinc powder, but the binding force with zinc powder is still weak, resulting in poor stability during long-term deposition and dissolution cycles. Summary of the invention

[0003] The technical problems to be solved by the present invention are:

[0004] The existing MXene-modified zinc powder electrodes have insufficient adhesion and hydrophilicity-induced corrosion and hydrogen evolution reactions, resulting in poor long-cycle stability of the zinc powder negative electrode.

[0005] The present invention adopts the following technical solutions to solve the above technical problems:

[0006] The present invention provides a method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer, the method comprising the following steps:

[0007] (1) preparing mixed solution A: weigh zinc powder, add it to DMDAAC solution, and stir thoroughly to obtain mixed solution A;

[0008] (2) preparing mixed solution B: weighing MXene material, adding deionized water, and ultrasonically treating to prepare a colloidal dispersion to obtain mixed solution B;

[0009] (3) Electrostatic self-assembly method: Mixture A is added to mixture B to form a suspension, which is stirred vigorously to generate a precipitate;

[0010] (4) washing and drying: collecting the precipitate obtained in step (3), washing, and drying to obtain the zinc powder composite D-MXene@Zn-p;

[0011] (5) Preparation of zinc powder negative electrode sheet: Weigh D-MXene@Zn-p, conductive carbon black and polyvinylidene fluoride (PVDF), mix them, add solvent, and grind them thoroughly to form a slurry; evenly coat the slurry on the current collector and dry it to obtain a zinc powder composite negative electrode for an aqueous zinc ion battery.

[0012] Furthermore, in step (1), (800-900) mg of zinc powder is added to every (200-400) μL of DMDAAC solution, and the specification of the DMDAAC solution is a 65% or 60% aqueous solution.

[0013] Furthermore, the content of MXene material in the mixed solution B is 1 mg / mL.

[0014] Furthermore, the drying condition in step (4) is drying at 60-90° C. for 12-24 hours.

[0015] Furthermore, the drying condition in step (5) is drying at 60-90° C. for 12-24 hours.

[0016] Furthermore, in step (5), the mass ratio of D-MXene@Zn-p, conductive carbon black and polyvinylidene fluoride (PVDF) is 6-8:1-3:1-2.

[0017] Furthermore, the thickness of the zinc powder composite negative electrode described in step (5) is 27 to 30 μm.

[0018] Furthermore, in step (2), the MXene material is Ti3C2T x MXene material, a preparation method thereof, comprising the following steps: firstly dissolving LiF in HCl solution to obtain a mixed etching solution; then gradually adding Ti3AlC2 into the mixed etching solution, stirring and reacting at 40°C for 48 hours, centrifuging and washing after the reaction, ultrasonically treating the obtained precipitate in an ice water bath for 2 hours, and forming a multilayer Ti3C2T x Peel off into fewer layers or single-layer Ti3AlC2 nanosheets, and dry them to obtain Ti3C2T x MXene materials.

[0019] The present invention provides a compact hydrophobic zinc powder negative electrode based on an electrode enhancer, and the electrode is prepared by the method described in any one of the above technical solutions.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The invention provides a compact hydrophobic zinc powder negative electrode based on an electrode enhancer and a preparation method thereof. Dimethyldiallylammonium chloride (DMDAAC) is introduced as a bifunctional electrode enhancer, and its unique chemical structure and functional groups are utilized to prepare a zinc powder composite with zinc powder through an electrostatic self-assembly method, so that side reactions such as dendrite growth and hydrogen evolution are effectively inhibited, and the desolvation phenomenon of zinc ions in an electrolyte is reduced, thereby promoting the deposition and dissolution of zinc during the charge and discharge process, enhancing the hydrophobicity of the electrode surface, and also significantly enhancing the binding force between the two, which can effectively solve the problems of zinc dendrite growth, corrosion and hydrogen evolution, and significantly improve the long-cycle stability of the zinc negative electrode.

[0022] The present invention can be extended to the preparation of zinc negative electrodes modified with other MXene materials, and can be widely used in energy storage devices, such as energy storage of small electronic products such as electronic watches, light bulbs, and toys, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a picture of the supernatant after the reaction of D-MXene@Zn-p prepared by the electrostatic self-assembly method in an embodiment of the present invention;

[0024] Figure 2 Schematic diagram of the preparation process of the zinc powder composite negative electrode in an embodiment of the present invention;

[0025] Figure 3 MXene Ti3C2T in the embodiment of the present invention x AFM images of materials;

[0026] Figure 4 MXene, DMDAAC and Zeta value after reaction and phenomenon diagram in the embodiment of the present invention;

[0027] Figure 5 The SEM and EDS images of the materials in the embodiments of the present invention are shown;

[0028] Figure 6 is the Fourier infrared spectrum of the material in the embodiment of the present invention;

[0029] Figure 7 This is a comparison diagram of contact angle tests before and after adding an electrode enhancer in an embodiment of the present invention;

[0030] Figure 8 : is the contact angle diagram of the D-MXene@Zn-p electrode in the embodiment of the present invention; Fig. 9 is a Tafel polarization curve diagram of a three-electrode system in an embodiment of the present invention;

[0031] Fig.10 It is the adsorption energy diagram of Zn-p, MXene@Zn and D-MXene@Zn-p on different crystal planes of Zn in the embodiment of the present invention;

[0032] Fig.11 This is a graph showing a cycle test of a zinc negative electrode symmetrical battery in an embodiment of the present invention;

[0033] Fig.12 The SEM image of the zinc powder negative electrode after cycling in the embodiment of the present invention is

[0034] Fig.13 This is a full battery cycle test curve in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the scheme of the present invention, exemplary implementations or embodiments of the present invention will be described below in conjunction with the accompanying drawings. Obviously, the described implementations or embodiments are only implementations or embodiments of a part of the present invention, not all of them. Based on the implementations or embodiments of the present invention, all other implementations or embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present invention.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0037] The raw materials and reagents used in this example are not limited to specific sources and can be purchased from commercial channels or prepared according to conventional technical methods in the field. The selection of the materials used should meet the relevant technical requirements and should have sufficient purity and stability to ensure the consistency and reliability of the experimental process and the final product.

[0038] In a typical embodiment of the present invention, a method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer is provided, comprising the following steps:

[0039] (1) Preparing mixed solution A: Weigh a certain amount of zinc powder and add it to a dimethyldiallylammonium chloride (DMDAAC) solution. Mix the zinc powder and the DMDAAC solution under sufficient stirring to obtain a mixed solution A;

[0040] (2) Preparing mixed solution B: Weigh a certain amount of MXene, add deionized water, and perform ultrasonic treatment to prepare a colloidal dispersion to obtain mixed solution B;

[0041] (3) Electrostatic self-assembly method: The mixed solution A obtained in step (1) is added to the mixed solution B obtained in step (2) to form a suspension. The mixture is stirred vigorously for 5 to 30 minutes to cause flocculation and stratification of the suspension. The suspension is allowed to stand for a period of time until the supernatant is completely clarified.

[0042] (4) washing and drying: collecting the precipitate obtained in step (3), washing it with deionized water for multiple times to remove impurities, and drying it to obtain the zinc powder composite D-MXene@Zn-p;

[0043] (5) Preparation of zinc powder negative electrode sheet: zinc powder composite D-MXene@Zn-p, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed, N-methylpyrrolidone (NMP) is added as a solvent, and the mixture is fully ground into a slurry; the slurry is evenly coated on a current collector and dried to obtain a zinc powder composite negative electrode for an aqueous zinc ion battery.

[0044] In this embodiment, a compact hydrophobic zinc powder negative electrode based on an electrode enhancer is provided, and dimethyldiallyl ammonium chloride (DMDAAC) is used as a bifunctional electrode enhancer to achieve a synergistic improvement in the performance of the zinc negative electrode through the synergistic effect of a specific molecular structure. On the one hand, the unsaturated carbon chain (CC, C=C) in the DMDAAC molecule constructs a hydrophobic three-dimensional network protective layer on the surface of the zinc powder through chemical modification, which effectively avoids the corrosion of the zinc negative electrode by active water in the electrolyte and the side reaction of hydrogen evolution, thereby effectively improving the electrochemical performance and long-cycle stability of the zinc powder negative electrode; on the other hand, the quaternary ammonium group (-N(CH3)2 + ) carries a large amount of cationic charge, which makes its aqueous solution have significant positive charge, and can combine with negatively charged MXene materials (such as Ti3C2Tx, Nb2CTx, etc.) through electrostatic interaction to keep the structural integrity of the modified zinc powder negative electrode during the cycle. The introduction of MXene materials can further improve the mechanical strength, conductivity and overall electrochemical performance of the zinc negative electrode.

[0045] In a typical embodiment of the present invention, preferably, in step (1), (800-900) mg of zinc powder is added to each (200-400) μL of DMDAAC solution, and the mixture is stirred for 1-5 hours to obtain a mixed solution A; the mixed solution A has positive charge and can enhance the interaction between zinc powder and other materials through electrostatic adsorption; the concentration of the DMDAAC solution is 65% or 60% aqueous solution, and the chemical formula of DMDAAC is C8H 16 NCl, the structural formula is [(CH3)2N + (CH2CH=CH2)2]·Cl - ).

[0046] In a typical embodiment of the present invention, preferably, the content of MXene material in the mixed solution B in step (2) is 1 mg / mL.

[0047] The MXene is a two-dimensional transition metal carbide, nitride or carbonitride material, and the molecular formula is M n+ 1X n T x (n=1-3), where M is a transition metal from the first few groups, A is a main group element, X is a C and / or N element, T x Represents a surface terminal group (including OH, O or F). Specifically, it also includes but is not limited to Ti3C2T x 、Nb2CT x 、V2CT x 、MoCT x 、Ta3C2T x 、Ti3N2T x and W3CT x , with a two-dimensional layered structure; its Zeta potential is electronegative, which is conducive to electrostatic binding with the positively charged Zn / DMDAAC solution;

[0048] In a typical embodiment of the present invention, preferably, the stirring time in step (3) is 15 minutes.

[0049] In a typical embodiment of the present invention, preferably, the drying condition in step (4) is drying at 60-90° C. for 12-24 hours.

[0050] In a typical embodiment of the present invention, preferably, the drying conditions in step (5) are vacuum drying at 60-90° C. for 12-24 hours.

[0051] In a typical embodiment of the present invention, preferably, in step (5), the mass ratio of D-MXene@Zn-p, conductive carbon black and polyvinylidene fluoride (PVDF) is 6-8:1-3:1-2.

[0052] In a typical embodiment of the present invention, preferably, the thickness of the zinc powder composite negative electrode in step (5) is 27 to 30 μm.

[0053] In a typical embodiment of the present invention, preferably, the Ti3C2T x The preparation method of Mxene includes: firstly dissolving LiF in HCl solution to obtain a mixed etching solution; then gradually adding Ti3AlC2 into the mixed etching solution, stirring and reacting at 40°C for 48 hours, centrifuging and washing after the reaction, ultrasonically treating the obtained precipitate in an ice water bath for 2 hours, and forming a multilayer Ti3C2Tx Peel off into a single layer or a few layers of Ti3AlC2, dry and obtain MXene Ti3C2T x .

[0054] In a typical embodiment of the present invention, a carbon material is used to replace Ti3C2Tx Mxene in step (2), and finally a zinc powder composite negative electrode for an aqueous zinc ion battery is prepared. The carbon material includes one or more of graphite, carbon nanotubes or graphene. The beneficial effects of the present invention will be described below in conjunction with specific embodiments and comparative examples.

[0055] Example 1

[0056] A method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer, such as Figure 2 As shown, the method comprises the following steps: (1) preparing a mixed solution A: weighing 900 mg of zinc powder and adding it into 400 μL of DMDAAC solution (65%), stirring for 2 hours to fully mix, and obtaining a mixed solution A.

[0057] (2) Preparation of mixed solution B: Preparation of Ti3C2Tx Mxene: First, 2 g LiF was dissolved in 40 mL 9 mol·L - 1 HCl solution to obtain a mixed etching solution; then, 2g Ti3AlC2 was gradually added to the mixed etching solution and stirred at 40°C for 48 hours. After the reaction was completed, centrifugation was performed and washed until the pH value of the supernatant was about 6. The obtained precipitate was ultrasonically treated in an ice water bath for 2 hours to form a multilayer Ti3C2T x Exfoliate into fewer layers or a single layer of Ti3AlC2 and dry to obtain MXene Ti3C2T x Materials. Figure 3 As shown, the MXene Ti3C2T x The layer thickness of the material is ≤5 μm, and the single layer thickness is distributed in the range of 1 to 3 μm, indicating that the etching of a single layer or a few layers of Ti3A1C2 is successful.

[0058] Weigh 10 mg of Ti3C2Tx MXene, add 10 mL of deionized water, and prepare the colloidal dispersion by ultrasonication to obtain a 1 mg / mL mixed solution B.

[0059] (3) Electrostatic self-assembly method: Figure 4 As shown, mixed solution A is added to mixed solution B to form a suspension, and the suspension is vigorously stirred to aggregate to obtain a flocculent precipitate. The Zeta value of mixed solution B is -50.5 mV, the Zeta value of the DMDAAC solution diluted three times is +29.8 mV, and the Zeta value of the supernatant after the reaction is +2.8 mV.

[0060] (4) Washing and drying: The flocculent precipitate was collected, washed, and dried at 80 °C for 12 h to obtain the zinc powder composite D-MXene@Zn-p.

[0061] (5) Preparation of zinc powder negative electrode sheet: Weigh 7 g of D-MXene@Zn-p, 2 g of conductive carbon black and 1 g of polyvinylidene fluoride (PVDF), add solvent NMP, mix and grind thoroughly to form a slurry; evenly coat the slurry on the current collector and dry at 90 °C for 12 h to obtain a zinc powder composite D-MXene@Zn-p negative electrode for an aqueous zinc ion battery.

[0062] The prepared zinc negative electrode, positive electrode and glass fiber separator were punched into discs with diameters of 12mm, 14mm and 18mm respectively, and assembled into symmetrical cells in the order of zinc negative electrode, separator and zinc negative electrode, and assembled into full cells in the order of negative electrode, separator and positive electrode for electrochemical performance testing. The electrode sheets were separated by a glass fiber separator, and a 2mol / L zinc sulfate (ZnSO4) solution was used as the electrolyte for the half-cell or symmetrical cell. When MnO2 was used as the positive electrode to assemble into a full cell, 2mol / L ZnSO4+0.2MnSO4 was prepared as the electrolyte to inhibit the dissolution of manganese.

[0063] Example 2

[0064] The difference between this example and example 1 is that in step (1) of preparing mixed solution A, 850 mg of zinc powder is weighed and added into 400 μL of DMDAAC solution (65%), and stirred for 2 h to fully mix, thereby obtaining mixed solution A.

[0065] Example 3

[0066] The difference between this example and example 1 is that in step (1) of preparing mixed solution A, 800 mg of zinc powder is weighed and added into 400 μL of DMDAAC solution (65%), and stirred for 2 h to fully mix, thereby obtaining mixed solution A.

[0067] like Figure 1 As shown, the supernatants of the reactions of D-MXene@Zn-p prepared by the electrostatic self-assembly method in Examples 1, 2 and 3 show that the reaction in Example 1 was the most complete and the supernatant was the clearest.

[0068] Example 4

[0069] (1) Preparation of solution A: Weigh 900 μg of zinc powder and add it to 400 μm DMDAAC solution (65%). Stir for 2 h to ensure thorough mixing, to obtain mixed solution A.

[0070] (2) Preparation of solution B: Weigh 10 mg of Nb2CTxMXene, add 10 mL of ultrapure water, and prepare a colloidal dispersion by ultrasonication to obtain a 1 mg / mg mixed solution B.

[0071] (3) Electrostatic self-assembly method: Mixture A is added to mixture B to form a suspension, which is stirred vigorously. After 20 minutes, the suspension is aggregated to obtain a flocculent precipitate.

[0072] (4) Washing and drying: The flocculent precipitate was collected, washed, and dried at 90 °C for 24 h to obtain the zinc powder composite D-MXene@Zn-p, denoted as D-MXene@Zn-p.

[0073] (5) Preparation of zinc powder negative electrode sheet: zinc powder composite D-MXene@Zn-p, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed, N-methylpyrrolidone (NMP) is added as a solvent, and the mixture is fully ground into a slurry; the slurry is evenly coated on a current collector and dried to obtain a zinc powder composite D-MXene@Zn-p negative electrode for an aqueous zinc ion battery.

[0074] Example 5

[0075] The difference between this embodiment and embodiment 4 is that in step (1) of preparing solution A, 900 μg of zinc powder is weighed and added into 200 μm DMDAAC solution (65%), and stirred for 2 h to ensure sufficient mixing, thereby obtaining mixed solution A.

[0076] Example 6

[0077] The difference between this embodiment and embodiment 4 is that in step (2) of preparing solution B, 10 mg of Ti3N2T x MXene, add 10 mL of ultrapure water, and prepare the colloidal dispersion by ultrasound to obtain a mixed solution B of 1 mg / mg.

[0078] Comparative Example 1

[0079] (1) Weigh 900 mg of zinc powder;

[0080] Weigh 10 mg of Ti3C2Tx MXene, add 10 mL of deionized water, and prepare the colloidal dispersion by ultrasonication to obtain a 1 mg / mL mixed solution B.

[0081] (2) Preparation of mixed solution B: weigh 10 mg Ti3C2T x MXene, add 10 mL of deionized water, and prepare the colloidal dispersion by ultrasound to obtain a mixed solution B of 1 mg / mL.

[0082] (3) Electrostatic self-assembly method: 900 mg of zinc powder was added to mixed solution B to form a suspension. The suspension was stirred vigorously for 60 min and allowed to aggregate. The suspension was allowed to stand for 2 h to obtain a flocculent precipitate.

[0083] (4) Washing and drying: The flocculent precipitate was collected, washed, and dried at 60 °C for 24 h to obtain the zinc powder composite MXene@Zn-p.

[0084] (5) Preparation of zinc powder negative electrode sheet: zinc powder composite D-MXene@Zn-p, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed, N-methylpyrrolidone (NMP) is added as a solvent, and the mixture is fully ground into a slurry; the slurry is evenly coated on a current collector and dried to obtain a zinc powder composite MXene@Zn-p negative electrode for an aqueous zinc ion battery.

[0085] like Figure 5 The figure shows the electron scanning electron micrographs (SEM) of the D-MXene@Zn-p material of Example 1 and the MXene@Zn-p material of Comparative Example 1. It can be seen that the surface of MXene@Zn-p has curled MXene nanosheets distributed, the structure is loose, and the surface distribution is uneven. This is caused by the insufficient binding force between MXene and zinc powder, while the surface of D-MXene@Zn-p forms a tight three-dimensional network structure. Figure 5 c It can be seen that the main elements of the modified D-MXene@Zn-p, Zn, Ti, C, and N, are evenly distributed on the surface of the D-MXene@Zn-p particles.

[0086] Comparative Example 2

[0087] (1) Weigh 900 mg of zinc powder;

[0088] (2) Preparation of zinc powder negative electrode sheet: Pure zinc powder, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed, N-methylpyrrolidone (NMP) is added as a solvent, and the mixture is fully ground to form a slurry; the slurry is evenly coated on a current collector and dried to obtain a zinc powder negative electrode for an aqueous zinc ion battery, which is denoted as Zn-p.

[0089] Ti3C2T x MXene, DMDAAC, the zinc powder composite D-MXene@Zn-p of Example 1 and the composite zinc powder material MXene@Zn-p of Comparative Example 1 were subjected to Fourier transform infrared spectroscopy detection. Figure 6 As shown, MXene is at 1484 cm -1 The OH peaks and DMDAAC peaks are at 3430 cm -1 、3027cm -1 、2980cm -1 、1644cm-1 and 1480cm -1 The peaks appear at 3400-3500 cm-1, corresponding to the absorption of -OH, CH, C=C and CC bonds. The peaks of MXene@Zn-p and D-MXene@Zn-p zinc powder anode are at 3400-3500 cm-1. -1 There is an obvious wide-band -OH base peak at 3452 cm-1, which is mainly derived from the -OH in MXene and DDA. Compared with MXene@Zn material, the -OH peak of D-MXene@Zn-p material is at 3452 cm-1. -1 and 1595cm -1 The red shift phenomenon occurred at all places. This is mainly due to the influence of intermolecular hydrogen bonds on concentration. After adding DMDAAC, -OH bonds occurred and the concentration was diluted, causing the peak position to change and move to a higher wave number. In addition, the C=C bond (1644cm -1 ) and CC(1480cm -1 ) vibration bands, indicating the successful composite of MXene and DMDAAC on the surface of zinc powder.

[0090] like Figure 7 As shown, 2M ZnSO4 electrolyte was added to the surface of the MXene@Zn-p electrode of Comparative Example 1 and the D-MXene@Zn-p electrode of Example 1 to test the contact angle. The contact angle of the MXene@Zn-p electrode was 84.01°, showing hydrophilicity, and the contact angle of the D-MXene@Zn-p electrode was 134.97°, showing hydrophobicity. Figure 8 As shown, the contact angle of the D-MXene@Zn-p electrode prepared in Example 5 is 130°, showing hydrophobicity, and the contact angle is slightly smaller than the contact angle of the D-MXene@Zn-p electrode in Example 1 (134.97°).

[0091] The electrochemical performance of the D-MXene@Zn-p anode of Example 4 and the MXene@Zn anode and electrolyte of Comparative Example 1 were evaluated using a three-electrode system, wherein the zinc powder anode was the working electrode, the Ti foil was the counter electrode, the Ag / AgCl electrode was the reference electrode, and 2M ZnSO4 was used as the electrolyte. The Tafel polarization curve (Tafel) test was performed on an electrochemical workstation. Fig. 9 As shown, the results show that compared with MXene@Zn, the D-MXene@Zn-p electrode has a higher corrosion potential of -0.957V and a lower corrosion current. It can be seen that the hydrophobic layer of the modified D-MXene@Zn-p zinc anode can effectively inhibit the side reaction with water in the electrolyte to improve the corrosion resistance of the Zn anode.

[0092] Density functional theory was used to calculate the adsorption energy of the D-MXene@Zn-p material of Example 4 and the MXene@Zn-p material of Comparative Example 1 on the Zn(002) surface. ads ) Calculation follows formula E ads =E complex -(E a +E b ), where E complex is the total energy of the complex of molecules A and B, E A and E B are the total energies of isolated molecules A and B respectively. The results are as follows Fig.10 As shown in the figure, the adsorption energy of D-MXene@Zn-p on the Zn(002) surface reaches -3.86 eV, which is significantly higher than -2.53 eV of MXene@Zn, while -2.53 eV of MXene@Zn is significantly higher than -1.41 eV of pure zinc powder Zn-p in comparative example 2, indicating that Zn 2+ The interaction between D-MXene@Zn-p and Zn is the strongest, and this strong interaction promotes the 2+ More uniform deposition on the zinc negative electrode; compared with the bare zinc powder negative electrode, the addition of Mxene helps the deposition of zinc ions and improves the cycle performance.

[0093] The D-MXene@Zn-p electrodes prepared in Example 1 were assembled into symmetrical cells, separated by glass fiber as a separator, and 2M ZnSO4 was added as the electrolyte. -2 / / 1mA h cm -2 The cycling performance test was performed for 50 cycles. At the same time, the MXene@Zn-p in comparative example 1 was assembled into a symmetrical battery as a control group. Fig.11 As shown, MXene@Zn-p was polarized and failed after only 76 hours of cycling, while the cyclability of the D-MXene@Zn-p electrode in Example 1 was able to stably operate for more than 300 hours, significantly improving the cycling stability of the zinc powder anode.

[0094] The D-MXene@Zn-p electrodes prepared in Example 6 were assembled into a symmetrical battery and heated to 1 mA cm -2 / / 1mA h cm -2 Perform 50 cycles of cycle performance test. Fig.12As shown in the figure, after 50h of cycling, a large number of cracks have appeared on the surface of the MXene@Zn electrode. This may be due to the insufficient bonding between MXene and zinc powder, which gradually separates from the surface of zinc powder during the cycling process. However, the surface of the D-MXene@Zn-p electrode can still remain flat, without obvious dendrites and by-products, which shows that the introduction of DMDAAC can effectively enhance the bonding between MXene and the zinc powder surface, helping to inhibit the occurrence of dendrites and side reactions.

[0095] The MnO2 positive electrode was assembled with the D-MXene@Zn-p negative electrode of Example 6, the MXene@Zn-p negative electrode of Comparative Example 1, and the pure zinc negative electrode Zn-p of Comparative Example 2 into a full battery for cycle performance testing; Fig.13 As shown in the figure, the capacity of the MnO2||MXene@Zn-p full battery dropped sharply after 123 cycles, and the battery failed after only 452 cycles. The discharge capacity retention rate of MnO2||D-MXene@Zn-p reached 82.2% after 1000 cycles at 1A g-1, and the CE was close to 100%, which shows that the cycle performance and capacity retention rate of the zinc powder composite negative electrode modified by DMDAAC have been significantly improved; and the performance of the full battery MnO2||MXene@Zn-p has been significantly improved compared with that of bare zinc MnO2||Zn-p.

[0096] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer, characterized in that: The method comprises the following steps: (1) preparing mixed solution A: weigh zinc powder, add it to DMDAAC solution, and stir thoroughly to obtain mixed solution A; (2) preparing mixed solution B: weighing MXene material, adding deionized water, and ultrasonically treating to prepare a colloidal dispersion to obtain mixed solution B; (3) Electrostatic self-assembly method: Mixture A is added to mixture B to form a suspension, which is stirred vigorously to generate a precipitate; (4) washing and drying: collecting the precipitate obtained in step (3), washing, and drying to obtain the zinc powder composite D-MXene@Zn-p; (5) Preparation of zinc powder negative electrode sheet: Weigh D-MXene@Zn-p, conductive carbon black and polyvinylidene fluoride (PVDF), mix them, add solvent, and grind them thoroughly to form a slurry; evenly coat the slurry on the current collector and dry it to obtain a zinc powder composite negative electrode for an aqueous zinc ion battery.

2. The method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer according to claim 1, characterized in that: In step (1), (800-900) mg of zinc powder is added to every (200-400) μL of DMDAAC solution, and the specification of the DMDAAC solution is a 65% or 60% aqueous solution.

3. The method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer according to claim 2, characterized in that: The content of MXene material in the mixed solution B is 1 mg / mL.

4. The method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer according to claim 3, characterized in that: The drying conditions in step (4) are drying at 60-90° C. for 12-24 hours.

5. The method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer according to claim 4, characterized in that: The drying conditions in step (5) are drying at 60 to 90° C. for 12 to 24 hours.

6. The method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer according to claim 5, characterized in that: In step (5), the mass ratio of D-MXene@Zn-p, conductive carbon black and polyvinylidene fluoride (PVDF) is (6-8): (1-3): (1-2).

7. The method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer according to claim 6, characterized in that: The thickness of the zinc powder composite negative electrode described in step (5) is 27 to 30 μm.

8. The method for preparing a compact hydrophobic zinc powder negative electrode based on an electrode enhancer according to claim 7, characterized in that: In step (2), the MXene material is Ti3C2T x MXene material, a preparation method thereof, comprising the following steps: firstly dissolving LiF in HCl solution to obtain a mixed etching solution; then gradually adding Ti3AlC2 into the mixed etching solution, stirring and reacting at 40°C for 48 hours, centrifuging and washing after the reaction, ultrasonically treating the obtained precipitate in an ice water bath for 2 hours, and forming a multilayer Ti3C2T x Peel off into fewer layers or single-layer Ti3AlC2 nanosheets, and dry them to obtain Ti3C2T x MXene materials.

9. A compact hydrophobic zinc powder negative electrode based on an electrode enhancer, characterized in that: The electrode is prepared by the method according to any one of claims 1 to 8.

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