Preparation method of aqueous zinc-ion battery anode material with composite gel interface layer

Abstract

This invention relates to aqueous zinc-ion battery technology, aiming to provide a method for preparing an aqueous zinc-ion battery anode material with a composite gel interface layer. The method includes: adding sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, sodium nitrate, and MXene powder to a sufficient amount of potassium chloride aqueous solution; stirring to form a homogeneous solution; transferring the solution to a three-electrode electrolytic cell as the reaction medium; constructing an electrochemical workstation using platinum electrodes and zinc foil; and polymerizing and growing an MXene / sodium polyacrylate composite gel layer on the zinc foil; after removal, soaking and drying, a negative electrode material for aqueous zinc-ion batteries is obtained, with a composite gel interface layer on its surface. This invention, through in-situ electropolymerization, coats the surface of the zinc foil with an organic-inorganic composite gel interface protective layer, which can effectively adsorb zinc ions in the solution and guide the uniform deposition of zinc ions, thereby inhibiting the growth of zinc dendrites; it can also inhibit water corrosion of zinc and effectively improve the electrochemical performance and cycle life of the battery.

Description

Technical Field

[0001] This invention belongs to the field of aqueous ion battery technology, and specifically relates to a method for preparing an aqueous zinc ion battery anode material with a composite gel interface layer. Background Technology

[0002] The rapid development of the social economy necessitates accelerating the development and application of clean energy to reduce the environmental damage caused by fossil fuel use. Benefiting from the development of the new energy vehicle industry, the increasing demand for power batteries has also driven the development of lithium batteries. However, lithium battery electrolytes are generally composed of high-purity organic solvents, lithium electrolyte salts, and additives, with organic solvents typically accounting for 80-90%. The use of large amounts of flammable and toxic organic solvents raises concerns about the safety of lithium batteries and increases the difficulty of battery recycling. Furthermore, lithium metal resources are limited and expensive, and its poor flexibility makes it unsuitable for powering flexible electronic devices. These factors severely restrict the development of lithium batteries. Therefore, there is an urgent need to find safer new rechargeable batteries to meet these development needs.

[0003] Zinc possesses a low equilibrium potential and a high overpotential for hydrogen reactions, making it the element with the lowest standard potential among all elements that can be efficiently reduced from aqueous solutions. Its theoretical specific capacity is as high as 820 mAh g⁻¹. -1 Among the metallic elements that are stable in aqueous solutions, zinc has the highest energy density. Furthermore, zinc is abundant, has low toxicity, and is easy to process. In addition, aqueous electrolytes are mostly aqueous solutions, avoiding the use of organic ethers. Their ionic conductivity is two orders of magnitude higher than that of organic electrolytes, resulting in aqueous batteries typically having higher power density, and they are also easy to manufacture and inexpensive. Therefore, inexpensive, safe, environmentally friendly, and high-power aqueous ion batteries are ideal green battery systems.

[0004] In current research on aqueous ion batteries, most researchers focus on strategies that can be applied to new cathode materials and improve the performance of existing cathode materials. However, the anode also faces many problems, such as dendrite formation, deformation, hydrogen evolution, and passivation, which are the key factors restricting the performance improvement of aqueous ion batteries. Moreover, these problems are interconnected; if only one problem is improved during the structural design and performance improvement of the zinc anode, it may trigger multiple chain reactions, exacerbating the impact of other problems.

[0005] Therefore, proposing solutions for the preparation technology of negative electrode materials for aqueous ion batteries is of great significance for the research and development and production of high-performance aqueous ion batteries. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for preparing an aqueous zinc-ion battery anode material with a composite gel interface layer.

[0007] To solve the technical problem, the solution of the present invention is:

[0008] A method for preparing an aqueous zinc-ion battery anode material with a composite gel interface layer is provided, comprising the following steps:

[0009] (1) Add sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide and sodium nitrate to a sufficient amount of potassium chloride aqueous solution and stir at room temperature for 30 min; then add MXene powder and continue stirring to form a homogeneous solution;

[0010] (2) The homogeneous solution was transferred to a three-electrode electrolytic cell as a reaction medium. An electrochemical workstation was built with a platinum electrode as the counter electrode and reference electrode and a zinc foil as the working electrode. Under the electric field induction of the in-situ electropolymerization reaction, a free radical reduction reaction occurred on the surface of the zinc foil, and the polymer growth formed an MXene / sodium polyacrylate composite gel layer.

[0011] (3) The zinc foil loaded with the composite gel layer is immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; after being taken out and dried, a negative electrode material for aqueous zinc-ion batteries is obtained, which has a composite gel interface layer on its surface.

[0012] As a preferred embodiment of the present invention, in step (1), the concentration of the potassium chloride aqueous solution is 1 mol / L.

[0013] As a preferred embodiment of the present invention, in step (1), the mass ratio of sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, sodium nitrate and MXene powder is: 0.0825~2.64 : 0.12~3.84 : 0.054~1.728 : 0.212~6.80 : 0.001~0.15.

[0014] As a preferred embodiment of the present invention, in step (2), the in-situ electropolymerization reaction is controlled by cyclic voltammetry, constant current pulse method or constant voltage pulse method; when using constant voltage pulse method, the voltage range is -2 to 2V and the number of cycles is 1 to 300.

[0015] Alternatively, a more preferred voltage range is -0.7 to 0.7V, with 100 cycles.

[0016] As a preferred embodiment of the present invention, in step (3), the drying process is carried out under vacuum, and the temperature is controlled at 1 to 100°C and the time is 1 to 24 hours.

[0017] The present invention further provides a method for applying the negative electrode material obtained by the aforementioned method in the further preparation of aqueous zinc-ion batteries, wherein the negative electrode material is sliced ​​to obtain an electrode sheet, which is used as the negative electrode of the aqueous zinc-ion battery.

[0018] As a preferred embodiment of the present invention, the electrode sheet is a circular electrode sheet with a diameter of 1 to 19 mm.

[0019] As a preferred embodiment of the present invention, the aqueous zinc-ion battery is prepared by the following steps:

[0020] (1) The negative electrode material with composite gel interface layer is sliced ​​to obtain a circular electrode sheet, which is used as the negative electrode of the aqueous zinc-ion battery.

[0021] (2) Take MnO2, Super P and polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1, dissolve them together in an appropriate amount of N-methylpyrrolidone (NMP), mix them evenly to obtain a slurry; coat the slurry onto Ti foil, dry it at 60°C and under vacuum for 24 hours, and then cut it into circular electrode sheets as the positive electrode of the aqueous zinc-ion battery; the diameter of the positive electrode sheet is slightly smaller than that of the negative electrode sheet;

[0022] (3) Prepare a 2M ZnSO4 aqueous solution as the electrolyte for the aqueous zinc-ion battery; use a glass fiber membrane as the separator for the aqueous zinc-ion battery.

[0023] (4) Arrange the following components in the order of 2032 battery positive electrode shell, negative electrode, glass fiber membrane, ZnSO4 electrolyte, negative electrode, nickel foam, and 2032 battery negative electrode shell to assemble a symmetrical battery; or,

[0024] The 2032 battery is assembled by placing the positive electrode shell, positive electrode, glass fiber membrane, ZnSO4 electrolyte, negative electrode, nickel foam, and 2032 battery negative electrode shell in that order.

[0025] Description of the invention principle:

[0026] MXene is a graphene-like structure obtained by processing the MAX phase. The specific molecular formula of the MAX phase is M... n+1 AX n (n = 1, 2 or 3), where M refers to transition metals from the first few groups, A refers to main group elements, and X refers to C and / or N elements. Because MX has strong bond energies and A has high chemical reactivity, A can be removed from the MAX phase through etching, thus obtaining a graphene-like 2D structure—MXene.

[0027] To achieve the above objectives, this invention adds sodium acrylate as a monomer, ammonium persulfate as an initiator, N,N-methylenebisacrylamide as a crosslinking agent, sodium nitrate as a catalyst, and MXene powder as an inorganic conductive material to a KCl aqueous solution. After stirring until homogeneous, a homogeneous solution is formed and transferred to a three-electrode electrolytic cell as the reaction medium. An electrochemical workstation is constructed using platinum electrodes as the counter and reference electrodes and zinc foil as the working electrode. Through in-situ electropolymerization, under the stimulation of a pulsed cyclic electric field, the initiator ammonium persulfate generates a large number of free radicals. Under the continuous electric field, the acrylic monomer gradually undergoes a polymerization reaction to form sodium polyacrylate. Conductive MXene sheets are inserted into the sodium polyacrylate gel layer, forming an MXene / sodium polyacrylate composite gel layer.

[0028] In-situ growth can increase the bonding force between the gel layer and the metal substrate, improving the long-cycle stability of the battery. At the same time, the composite gel combines the network structure of organic sodium polyacrylate and the good conductivity of inorganic MXene, effectively shortening the electron and ion transport distance and increasing the electron transport rate through the highly conductive matrix, thereby effectively improving the rate performance of the battery.

[0029] This invention utilizes zinc foil modified with a network-structured gel interface as the negative electrode material for ion batteries, which can effectively shorten the transport distance of electrons and ions and achieve a uniform surface electric field distribution; the highly zinc-loving functional groups can effectively adsorb Zn. 2+ The uniform surface ion distribution lowers the nucleation barrier and reduces the nucleation overpotential, effectively suppressing zinc dendrite growth and forming a dendrite-free zinc anode. Therefore, batteries equipped with this dendrite-free anode exhibit excellent rate performance and long-cycle stability.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) This invention utilizes in-situ electropolymerization to coat the surface of zinc foil with a uniform and dense organic-inorganic composite gel interface protective layer. The numerous active groups (such as carboxyl and carbonyl groups) in this protective layer can interact strongly with zinc ions via electrostatics, effectively adsorbing zinc ions from the solution and guiding their uniform deposition, thereby inhibiting zinc dendrite growth. Furthermore, the active groups can alter the solvation structure of metal ions, forming a hydrogen bond network with free water, thus inhibiting water corrosion of zinc and effectively improving the electrochemical performance and cycle life of the battery.

[0032] (2) The technical solution of the present invention uses an organic-inorganic composite gel interface layer as the active material of the zinc metal anode protective layer to inhibit the growth of zinc metal anode dendrites and corrosion passivation during the charging and discharging process of zinc-ion battery, thereby greatly improving the cycle stability and electrochemical performance of the battery.

[0033] (3) The aqueous battery prepared using the technical solution of the present invention has a long cycle life and stable performance.

[0034] (4) The method of in-situ electropolymerization of gel interface layer on metal substrate adopted in this invention has universality and can be extended to metal substrates such as copper foil, titanium foil, and stainless steel foil, and has the same or similar technical effects.

[0035] (5) The present invention uses an organic-inorganic composite gel interface layer as a metal negative electrode protective layer, which has excellent performance, effectively suppresses the growth of negative electrode dendrites and the occurrence of side reactions. Furthermore, the aqueous zinc-ion battery prepared with it has high cycle stability and excellent rate performance, and is expected to accelerate the industrialization process of aqueous zinc-ion batteries. Attached Figure Description

[0036] Figure 1 The images show the surface morphology and cross-sectional thickness of the pure zinc foil and the negative electrodes prepared in Example 4 and Comparative Example 4 of this invention; (ac) are cross-sectional SEM images of the pure zinc foil, PAAS@Zn, and MX / PAAS@Zn, respectively; (df) are surface morphology SEM images of the pure zinc foil, PAAS@Zn, and MX / PAAS@Zn, respectively.

[0037] Figure 2 These are XPS high-resolution spectra of pure zinc foil and the negative electrodes prepared in Example 4 and Comparative Example 4 in this invention; (a) Zn 2p, (b) O 1s, (c) C 1s.

[0038] Figure 3 The following are the performance test results of the pure zinc foil and the negative electrode prepared in Example 4 and Comparative Example 4 assembled into a symmetrical battery: (a) Tafel curve, (b) ion transport number, (c) it curve, (d) Arrhenius curve.

[0039] Figure 4 The electrochemical performance test results of the pure zinc foil and the negative electrodes prepared in Example 4 and Comparative Example 4 in this invention assembled into symmetrical cells and Cu-Zn semi-symmetrical cells; (a) Symmetrical cells at 10 mA cm⁻¹ -2 10mAh cm -2 (b) Time-voltage curves of the Cu-Zn semi-symmetric cell at 10 mA cm⁻¹ -2 10mAh cm -2 Coulomb efficiency at 1 mA / cm², (c) symmetric cell -2 1mAh cm -2 The time-voltage curves of (d) Cu-Zn semi-symmetric cells at 1 mA cm⁻¹ -2 1mAh cm -2 Coulomb efficiency under [the specified conditions].

[0040] Figure 5 The electrochemical performance of the pure zinc foil and the negative electrode prepared in Example 4 and Comparative Example 4 assembled into a full cell is shown. (a) 0.2A g -1 Cycling performance (600 cycles), (b) MX / PAAS@Zn at 1A g -1 (c) Capacity-voltage curves of MX / PAAS@Zn at different rates, (d) Bar charts of capacity retention and capacity decay rate, and (e) Performance comparison chart. Detailed Implementation

[0041] The technical solution of the present invention will be further illustrated below through specific embodiments. These embodiments are merely illustrative of the invention and should not be considered as specific limitations thereof.

[0042] Example 1

[0043] 1. Preparation of aqueous zinc-ion battery anode material with composite gel interface layer:

[0044] (1) Weigh 0.0825g sodium acrylate, 0.12g ammonium persulfate, 0.054g N,N-methylenebisacrylamide and 0.212g sodium nitrate, dissolve them in 100mL of 1M (i.e. 1mol / L) potassium chloride aqueous solution, stir at room temperature for 30min, then add 0.001g MXene powder and continue stirring to form a homogeneous solution;

[0045] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -2V, the cutoff voltage to 2V, and the number of cycles to 1. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an MXene / sodium polyacrylate composite gel interface layer on the zinc foil;

[0046] (3) The zinc foil loaded with the composite gel interface layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 1°C for 24 hours to finally obtain the negative electrode material with the composite gel interface layer.

[0047] 2. Examples of application methods for preparing symmetric solar cells:

[0048] (1) The negative electrode material with composite gel interface layer is sliced ​​to obtain a circular electrode sheet, which is used as the negative electrode of the aqueous zinc-ion battery.

[0049] (2) Take MnO2, Super P and polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1, dissolve them together in an appropriate amount of N-methylpyrrolidone (NMP), mix them evenly to obtain a slurry; coat the slurry on Ti foil, dry it at 60°C and under vacuum for 24 hours, and then cut it into circular electrode sheets to serve as the positive electrode of an aqueous zinc-ion battery.

[0050] The diameter of the negative electrode sheet can be selected from 1 to 19 mm, and the diameter of the positive electrode sheet is slightly smaller than that of the negative electrode sheet;

[0051] (3) Prepare a 2M ZnSO4 aqueous solution as the electrolyte for the aqueous zinc-ion battery; use a glass fiber membrane as the separator for the aqueous zinc-ion battery.

[0052] (4) Arrange the positive electrode shell, negative electrode, glass fiber membrane, ZnSO4 electrolyte, negative electrode, nickel foam, and negative electrode shell of 2032 battery in sequence to form a symmetrical battery.

[0053] 3. Examples of application methods for preparing full cells:

[0054] (1) Prepare the battery components and electrolyte by referring to the steps in the method for preparing a symmetrical battery;

[0055] The difference is that the electrode on the positive side is a MnO2 electrode.

[0056] (2) Arrange the 2032 battery positive electrode shell, MnO2 positive electrode, glass fiber membrane, ZnSO4 electrolyte, negative electrode, nickel foam, and 2032 battery negative electrode shell in sequence to assemble a full battery.

[0057] Example 2

[0058] Preparation of aqueous zinc-ion battery anode material with composite gel interface layer:

[0059] (1) Weigh 0.165g sodium acrylate, 0.24g ammonium persulfate, 0.108g N,N-methylenebisacrylamide and 0.425g sodium nitrate, dissolve them in 100mL potassium chloride (1M), stir for 30min at room temperature, then add 0.005g MXene powder and continue stirring to form a homogeneous solution;

[0060] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -1V, the cutoff voltage to 1V, and the number of cycles to 100. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an MXene / sodium polyacrylate gel layer on the zinc foil;

[0061] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 20°C for 15 hours to finally obtain the negative electrode material with the composite gel interface layer.

[0062] The application method of this negative electrode material is described in Example 1.

[0063] Example 3

[0064] Preparation of aqueous zinc-ion battery anode material with composite gel interface layer:

[0065] (1) Weigh 0.33g sodium acrylate, 0.48g ammonium persulfate, 0.216g N,N-methylenebisacrylamide and 0.85g sodium nitrate, dissolve them in 100mL potassium chloride (1M), stir for 30min at room temperature, then add 0.015g MXene powder and continue stirring to form a homogeneous solution;

[0066] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -0.7V, the cutoff voltage to 0.7V, and the number of cycles to 100. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an MXene / sodium polyacrylate gel layer on the zinc foil;

[0067] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 40°C for 8 hours to finally obtain the negative electrode material with the composite gel interface layer.

[0068] The application method of this negative electrode material is described in Example 1.

[0069] Example 4

[0070] Preparation of aqueous zinc-ion battery anode material with composite gel interface layer:

[0071] (1) Weigh 0.66g sodium acrylate, 0.96g ammonium persulfate, 0.432g N,N-methylenebisacrylamide and 1.70g sodium nitrate, dissolve them in 100mL potassium chloride (1M), stir for 30min at room temperature, then add 0.02g MXene powder and continue stirring to form a homogeneous solution;

[0072] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -0.7V, the cutoff voltage to 0.7V, and the number of cycles to 100. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an MXene / sodium polyacrylate gel layer on the zinc foil;

[0073] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 60°C for 4 hours to finally obtain the negative electrode material with the composite gel interface layer.

[0074] The application method of this negative electrode material is described in Example 1.

[0075] Example 5

[0076] Preparation of aqueous zinc-ion battery anode material with composite gel interface layer:

[0077] (1) Weigh 1.32g sodium acrylate, 1.92g ammonium persulfate, 0.864g N,N-methylenebisacrylamide and 3.40g sodium nitrate, dissolve them in 100mL potassium chloride (1M), stir for 30min at room temperature, then add 0.1g MXene powder and continue stirring to form a homogeneous solution;

[0078] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -0.7V, the cutoff voltage to 0.7V, and the number of cycles to 100. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an MXene / sodium polyacrylate gel layer on the zinc foil;

[0079] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 70°C for 2 hours to finally obtain the negative electrode material with the composite gel interface layer.

[0080] The application method of this negative electrode material is described in Example 1.

[0081] Example 6

[0082] Preparation of aqueous zinc-ion battery anode material with composite gel interface layer:

[0083] (1) Weigh 2.64g sodium acrylate, 3.84g ammonium persulfate, 1.728g N,N-methylenebisacrylamide and 6.80g sodium nitrate, dissolve them in 100mL potassium chloride (1M), stir for 30min at room temperature, then add 0.15g MXene powder and continue stirring to form a homogeneous solution;

[0084] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -0.7V, the cutoff voltage to 0.7V, and the number of cycles to 300. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an MXene / sodium polyacrylate gel layer on the zinc foil;

[0085] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 100°C for 1 hour to finally obtain the negative electrode material with the composite gel interface layer.

[0086] The application method of this negative electrode material is described in Example 1.

[0087] Comparative Example 1

[0088] Preparation of battery anode materials with an all-organic hydrogel interface layer:

[0089] (1) Weigh 0.0825g sodium acrylate, 0.12g ammonium persulfate, 0.054g N,N-methylenebisacrylamide and 0.212g sodium nitrate, dissolve them in 100mL potassium chloride (1M), and stir for 30min at room temperature to form a homogeneous solution;

[0090] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -2V, the cutoff voltage to 2V, and the number of cycles to 1. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an organic sodium polyacrylate gel layer on the zinc foil;

[0091] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 1°C for 24 hours to finally obtain the battery anode material with a fully organic hydrogel interface layer.

[0092] Comparative Example 2

[0093] Preparation of battery anode materials with an all-organic hydrogel interface layer:

[0094] (1) Weigh 0.165g sodium acrylate, 0.24g ammonium persulfate, 0.108g N,N-methylenebisacrylamide and 0.425g sodium nitrate, dissolve them in 100mL potassium chloride (1M), and stir for 30min at room temperature to form a homogeneous solution;

[0095] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using the constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -1V, the cutoff voltage to 1V, and the number of cycles to 100. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an organic sodium polyacrylate gel layer on the zinc foil;

[0096] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 20°C for 15 hours to finally obtain the battery anode material with a fully organic hydrogel interface layer.

[0097] Comparative Example 3

[0098] Preparation of battery anode materials with an all-organic hydrogel interface layer:

[0099] (1) Weigh 0.33g sodium acrylate, 0.48g ammonium persulfate, 0.216g N,N-methylenebisacrylamide and 0.85g sodium nitrate, dissolve them in 100mL potassium chloride (1M), and stir for 30min at room temperature to form a homogeneous solution;

[0100] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -0.7V, the cutoff voltage to 0.7V, and the number of cycles to 100. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an organic sodium polyacrylate gel layer on the zinc foil;

[0101] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 40°C for 8 hours to finally obtain the battery anode material with a fully organic hydrogel interface layer.

[0102] Comparative Example 4

[0103] Preparation of battery anode materials with an all-organic hydrogel interface layer:

[0104] (1) Weigh 0.66g sodium acrylate, 0.96g ammonium persulfate, 0.432g N,N-methylenebisacrylamide and 1.7g sodium nitrate, dissolve them in 100mL potassium chloride (1M) and stir for 30min at room temperature to form a homogeneous solution;

[0105] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -0.7V, the cutoff voltage to 0.7V, and the number of cycles to 100. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an organic sodium polyacrylate gel layer on the zinc foil;

[0106] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 60°C for 4 hours to finally obtain the battery anode material with a fully organic hydrogel interface layer.

[0107] Comparative Example 5

[0108] Preparation of battery anode materials with an all-organic hydrogel interface layer:

[0109] (1) Weigh 1.32g sodium acrylate, 1.92g ammonium persulfate, 0.864g N,N-methylenebisacrylamide and 3.4g sodium nitrate, dissolve them in 100mL potassium chloride (1M) and stir for 30min at room temperature to form a homogeneous solution;

[0110] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -0.7V, the cutoff voltage to 0.7V, and the number of cycles to 100. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an organic sodium polyacrylate gel layer on the zinc foil;

[0111] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 70°C for 2 hours to finally obtain the battery anode material with a fully organic hydrogel interface layer.

[0112] Comparative Example 6

[0113] Preparation of battery anode materials with an all-organic hydrogel interface layer:

[0114] (1) Weigh 2.64g sodium acrylate, 3.84g ammonium persulfate, 1.728g N,N-methylenebisacrylamide and 6.8g sodium nitrate, dissolve them in 100mL potassium chloride (1M) and stir for 30min at room temperature to form a homogeneous solution;

[0115] (2) Using platinum electrodes as counter and reference electrodes and zinc foil as working electrodes, the homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium to build an electrochemical workstation; in-situ electropolymerization reaction was carried out on the electrochemical workstation using a constant voltage pulse method, with the initial voltage of the voltage pulse cycle set to -0.7V, the cutoff voltage to 0.7V, and the number of cycles to 300. Under the induction of the electric field, a free radical reduction reaction occurred, thereby electropolymerizing and growing an organic sodium polyacrylate gel layer on the zinc foil;

[0116] (3) The zinc foil loaded with the gel layer was immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; under vacuum conditions, it was dried at 100°C for 1 hour to finally obtain the battery negative electrode material with a fully organic hydrogel interface layer.

[0117] Performance testing and results evaluation:

[0118] 1. The following performance tests were performed on the negative electrode materials provided in Examples 1-6 and Comparative Examples 1-6:

[0119] (1) Characterization of surface morphology and cross-sectional thickness:

[0120] After being quenched with liquid nitrogen, zinc foil loaded with different interface layers is reduced to a surface area of ​​approximately 1 cm². 2 The test samples were freeze-dried and then subjected to field emission scanning electron microscopy (FESEM) to observe their surface morphology and cross-sectional thickness.

[0121] (2) Analysis of surface elements and structure:

[0122] After being quenched with liquid nitrogen, zinc foil loaded with different interface layers becomes a sample with a surface area of ​​approximately 1 cm². 2 The test samples were freeze-dried and then subjected to X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) to characterize their surface elements and structure.

[0123] (3) Electrochemical testing:

[0124] Anode materials with different interface layers from each embodiment and comparative example were cut into electrode sheets with a diameter of 14 mm, and their Tafel curves and linear voltammetry curves were tested in a three-electrode system. They were then assembled into symmetrical cells and full cells, and their impedance spectra and cyclic voltammetry curves were tested on an electrochemical workstation to characterize the electrochemical performance of different samples. The symmetrical cells, Cu-Zn semi-symmetrical cells, and full cells were then tested for their cycling performance at different rates using a Newwell battery testing system.

[0125] 2. Taking Example 4 and Comparative Example 4 as examples, Figures 1 to 5 The results of different performance tests for each product are displayed in the table.

[0126] Figure 1 The images show the surface morphology and cross-sectional thickness of the negative electrode; where (ac) represents the cross-sectional SEM images of pure zinc foil, PAAS@Zn, and MX / PAAS@Zn, respectively; and (de) represents the surface morphology SEM images of pure zinc foil, PAAS@Zn, and MX / PAAS@Zn, respectively.

[0127] As can be seen from the figure, the cross-sectional thickness of the organic-inorganic composite MX / PAAS@Zn is uniform and flat. At the same time, by comparing df, it can be seen that the cross-sectional gel layer of MX / PAAS@Zn has a good dense network structure.

[0128] Figure 2 The high-resolution XPS spectra of the negative electrode are shown; where (a) Zn 2p, (b) O 1s, and (c) C 1s.

[0129] As can be seen from the figure, the MX / PAAS@Zn anode is rich in zinc-loving functional groups C=C and C=O, which is beneficial for more uniform Zn adsorption. 2+ .

[0130] Figure 3 (a) Tafel curve, (b) ion transport number, (c) it curve, and (d) Arrhenius curve were measured for symmetrical cells.

[0131] As shown in the figure, (a) MX / PAAS@Zn has a lower corrosion potential and corrosion current, indicating better corrosion resistance; (b) MX / PAAS@Zn has a higher ion transference number, indicating that the organic-inorganic composite modified interface layer effectively adsorbs and promotes Zn. 2+ (c) MX / PAAS@Zn reached diffusion steady state in a faster time, indicating that its diffusion is faster; (d) MX / PAAS@Zn has a lower activation energy, indicating that its reactivity is greater.

[0132] Figure 4Electrochemical performance of the symmetrical cell and Cu-Zn semi-symmetrical cell assembled with the negative electrode; wherein (a) the symmetrical cell at 10 mA cm⁻¹ -2 10mAh cm -2 (b) Time-voltage curves of the Cu-Zn semi-symmetric cell at 10 mA cm⁻¹ -2 10mAh cm -2 Coulomb efficiency at 1 mA cm⁻¹, (c) symmetric cell -2 1mAh cm -2 The time-voltage curves of (d) Cu-Zn semi-symmetric cells at 1 mA cm⁻¹ -2 1mAh cm -2 Coulomb efficiency under [condition / condition].

[0133] As can be seen from the figure, in (a) and (c), the potential difference of MX / PAAS@Zn is smaller at the same time, indicating that it can more effectively suppress dendrite growth. In (b) and (d), the coulombic efficiency of the half-symmetric cell of MX / PAAS@Zn is higher, indicating that the cell has better reversibility during cycling.

[0134] Figure 5 Electrochemical performance of the cell assembled with the negative electrode as the full cell; where, (a) 0.2 A g -1 Cycling performance (600 cycles), (b) MX / PAAS@Zn at 1A g -1 (c) Capacity-voltage curves of MX / PAAS@Zn at different rates, (d) Bar charts of capacity retention and capacity decay rate, and (e) Performance comparison chart.

[0135] As can be seen from the figure, (ac) the capacity and coulombic efficiency of the MX / PAAS@Zn full cell are better than those of pure zinc foil (bare Zn) and PAAS@Zn, indicating that it has better cycle stability and reversibility; (d) the figure shows that MX / PAAS@Zn has high capacity retention and low capacity decay rate; (e) by comparing the cycle performance of different interface modification materials, the advantages of the MX / PAAS@Zn organic-inorganic composite interface can also be demonstrated.

[0136] Through experimental verification by the applicant, the experimental results and analytical conclusions of the remaining embodiments and comparative examples provided in this invention are generally similar to those of Embodiment 4 and Comparative Example 4. The above experimental conclusions indicate that with MXene doping, the gel layer becomes denser and stronger due to its conductivity and layered structure. The density of the deposited gel layer can be adjusted by controlling the number of cycles.

[0137] Based on the above analysis, it can be seen that the composite gel interface layer covering the surface of the negative electrode material of the present invention is an organic-inorganic composite gel prepared by in-situ electropolymerization. This gel has a good network structure, which is beneficial for ion transport. It also exhibits excellent hydrophilicity, ensuring sufficient wetting of the aqueous electrolyte. Furthermore, it possesses a large number of polar functional groups and good zinc affinity, which can effectively promote Zn deposition. 2+ Uniform nucleation and deposition of the anode are beneficial for suppressing dendrite growth, corrosion, and hydrogen evolution side reactions. Therefore, it can be applied to the preparation of dendrite-free anodes and the performance improvement of aqueous zinc-ion batteries.

[0138] Obviously, those skilled in the art can make various applications, additions, modifications, and variations to this invention without departing from its spirit and scope. For example, cyclic voltammetry and constant current pulse method are also common electrochemical deposition methods, and those skilled in the art will know and be able to use cyclic voltammetry or constant current pulse method to complete the relevant experimental operations. If various applications, additions, modifications, and variations based on this invention fall within the scope of the claims of this invention and their equivalents, then this invention also intends to include these applications, additions, modifications, and variations.

Claims

1. A method for preparing an aqueous zinc-ion battery anode material with a composite gel interface layer, characterized in that, Includes the following steps: (1) Add sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide and sodium nitrate to a sufficient amount of potassium chloride aqueous solution and stir at room temperature for 30 min; then add MXene powder and continue stirring to form a homogeneous solution; in the homogeneous solution, the mass ratio of sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, sodium nitrate and MXene powder is: 0.0825~2.64: 0.12~3.84: 0.054~1.728: 0.212~6.80: 0.001~0.15; (2) The homogeneous solution was transferred to a three-electrode electrolytic cell as the reaction medium. An electrochemical workstation was built with a platinum electrode as the counter electrode and reference electrode and a zinc foil as the working electrode. The in-situ electropolymerization reaction was carried out by cyclic voltammetry, constant current pulse method or constant voltage pulse method. The zinc foil surface underwent a free radical reduction reaction under the induction of electric field, and the polymer growth formed an MXene / sodium polyacrylate composite gel layer. (3) The zinc foil loaded with the composite gel layer is immersed in deionized water to remove the salt ions and unreacted residues attached to the surface; after being taken out and dried, a negative electrode material for aqueous zinc-ion batteries is obtained, which has a composite gel interface layer on its surface.

2. The method according to claim 1, characterized in that, In step (1), the concentration of the potassium chloride aqueous solution is 1 mol / L.

3. The method according to claim 1, characterized in that, In step (2), when the constant voltage pulse method is used, the voltage range is -2 to 2 V and the number of cycles is 1 to 300.

4. The method according to claim 1, characterized in that, In step (3), the drying process is carried out under vacuum, and the temperature is controlled at 1 to 100 °C for 1 to 24 hours.

5. The method for applying the negative electrode material prepared by the method of claim 1 in the further preparation of an aqueous zinc-ion battery, characterized in that, The negative electrode material is sliced ​​to obtain an electrode sheet, which is used as the negative electrode of an aqueous zinc-ion battery.

6. The method according to claim 5, characterized in that, The electrode sheet is a circular electrode sheet with a diameter of 1 to 19 mm.

7. The method according to claim 5, characterized in that, The aqueous zinc-ion battery is prepared according to the following steps: (1) The negative electrode material with composite gel interface layer is sliced ​​to obtain a circular electrode sheet, which is used as the negative electrode of the aqueous zinc-ion battery; (2) Take MnO2, Super P and polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1, dissolve them together in an appropriate amount of N-methylpyrrolidone (NMP), mix them evenly to obtain a slurry; coat the slurry onto Ti foil, dry it at 60°C and under vacuum for 24 h, and then cut it into circular electrode sheets as the positive electrode of the aqueous zinc-ion battery; the diameter of the positive electrode sheet is slightly smaller than that of the negative electrode sheet; (3) Prepare a 2 M ZnSO4 aqueous solution as the electrolyte for an aqueous zinc-ion battery; Glass fiber membrane is used as the separator for aqueous zinc-ion batteries; (4) Arrange the following components in sequence: positive electrode shell, negative electrode, glass fiber membrane, ZnSO4 electrolyte, negative electrode, nickel foam, and negative electrode shell of the 2032 battery, to assemble a symmetrical battery; or, The 2032 battery is assembled by placing the positive electrode shell, positive electrode, glass fiber membrane, ZnSO4 electrolyte, negative electrode, nickel foam, and 2032 battery negative electrode shell in that order.

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