Method for preparing aqueous zinc ion anode material, cathode and application

Abstract

The invention discloses a method for preparing an aqueous zinc ion anode material, a cathode and application, and belongs to the field of preparation of zinc ion battery electrode materials. The method comprises the step of calcining a titanium-hybridized metal organic framework in a vacuum or inert atmosphere, and the calcining is sufficient to convert the titanium-hybridized metal organic framework into a titanium dioxide hybrid modified mesoporous nitrogen-doped carbon framework. According to the method, the water-based zinc ion anode material with excellent performance can be prepared with a simple process, and a battery with long cycle life can be further obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of ion batteries, especially the field of zinc ion battery electrode material preparation, in particular, the present application relates to a method for preparing water-based zinc ion anode material, negative electrode and application. BACKGROUND

[0002] In recent years, with the progress of human society, the demand for energy of human beings shows a trend of continuous growth. However, the traditional energy is gradually exhausted, and its use also brings the problem of greenhouse effect that cannot be ignored. In view of this situation, developing clean and sustainable new energy has become an important task to be solved in current society.

[0003] Although wind energy, solar energy and tidal energy all belong to renewable energy, they cannot be used in large-scale energy storage systems due to the constraints of natural conditions. In contrast, as an excellent energy storage device, batteries have the advantages of high efficiency, low cost, safety and stability, and convenient use.

[0004] At present, lithium ion batteries have a high market share. The preparation process of lithium ion batteries is very mature, and they have many advantages. Lithium ion batteries have high energy density and stable cycle performance. However, lithium ion batteries also have many shortcomings that limit their development.

[0005] Firstly, the limited resources of lithium; secondly, the high production cost. In addition, lithium ion batteries have a large resistance, which leads to a small current discharge, so they are more used in small current electrical appliances. Lithium ion batteries also have the problem of dendrite growth that leads to a decrease in discharge capacity. In addition, lithium ion batteries also have the disadvantage of polluting the environment.

[0006] Therefore, new batteries need to be researched to replace lithium ion batteries. Compared with lithium batteries, metal ion aqueous solution batteries have the advantages of low cost, high safety and environmental friendliness. In common cases, multivalent metal batteries usually exhibit superior volume-specific capacity characteristics. However, most metal anode materials will form an inactive inert layer on their surface when they come into contact with water, which leads to passivation of the surface and thus reduces the performance of the material.

[0007] However, whether the electrolyte is an aqueous solution or a non-aqueous solution, zinc ion batteries can work stably and normally. At the same time, water-based zinc ion batteries are attracting the attention of researchers because of the advantages of Zn. Water-based zinc ion batteries exhibit many significant advantages. Thanks to the abundant Zn resources worldwide, the manufacturing cost is relatively low. At the same time, it has the characteristics of longer use time, stable working ability and environmental friendliness, making water-based zinc ion batteries a potential battery technology. Moreover, zinc ion batteries can be prepared in air environment, which is simple to make.

[0008] However, Zn metal anodes suffer from problems such as dendrite growth and hydrogen evolution. Therefore, developing dendrite-free zinc anodes that suppress side reactions on the anode surface is a perpetual goal pursued by researchers. Summary of the Invention

[0009] This application provides an example of a method for preparing an aqueous zinc ion anode material and a negative electrode. This method achieves chemical stability and a high number of active sites, thereby facilitating uniform zinc deposition and improving the cycle life of batteries based on this material.

[0010] The solution presented in this application is implemented through the following steps.

[0011] The method for preparing aqueous zinc ion anode materials disclosed herein includes: calcining a titanium-hybridized metal-organic framework under a vacuum or inert atmosphere, wherein the calcination is sufficient to convert the titanium-hybridized metal-organic framework into a titanium dioxide-hybridized mesoporous nitrogen-doped carbon framework.

[0012] Alternatively, the titanium-hybridized metal-organic framework is prepared using a solvothermal synthesis method. The solvothermal synthesis process is not only simple, but also produces materials with high crystallinity and purity, which can increase the reaction rate.

[0013] Optionally, in the reaction for preparing titanium-hybrid metal-organic frameworks by solvothermal synthesis, the titanium source reacts with organic acid ligands via a solvent.

[0014] Optionally, the solvent is a mixture of N,N-dimethylformyl and methanol, and the organic acid as a ligand includes 2-aminoterephthalic acid or terephthalic acid. In particular, the applicant notes that by using different ligands, it is possible to produce particulate matter with different morphologies, and the materials can have different specific surface areas and pore sizes. Of particular importance, the ligands can also significantly affect the dendrite suppression effect.

[0015] Optionally, the titanium source may include titanium isopropoxide or tetrabutyl titanate.

[0016] Optionally, the calcination method includes: subjecting the titanium-hybridized metal-organic framework to a heat treatment process in an argon atmosphere, heating it from room temperature to 400°C to 600°C at a heating rate of 1°C to 5°C / min and then holding it at that temperature. During this process, it can be determined that if the temperature rises too quickly, the material will be heated unevenly, preventing complete reaction and reducing the uniformity of the particles, thus degrading the material's properties. On the other hand, if the temperature is too low, carbon and nitrogen cannot be incorporated during calcination, resulting in fewer active sites and nucleation sites; while if the temperature is too high, the material's structure will collapse.

[0017] Optionally, the manufacturing method includes: N,N-Dimethylformamide and methanol are mixed at a volume ratio of 1:1 to 2:1 to dissolve terephthalic acid to a concentration of 0.1 mol / L to 0.15 mol / L to form a mixture; then tetrabutyl titanate is mixed with the mixture at a volume ratio of 1:100 to 5:100 under stirring; then the mixture is subjected to a solvothermal reaction in a hydrothermal reactor at 120℃ to 150℃ for 12 h to 36 h. The solvothermal reaction product was centrifuged, washed, and dried at 50℃~70℃ for 8h~12h to obtain titanium-hybrid metal-organic frameworks. Additionally, the titanium-hybrid metal-organic framework is heated in an argon atmosphere at a heating rate of 1~5℃ / min to calcine at 400~600℃ for a preset time.

[0018] On the other hand, the negative electrode based on aqueous zinc ion anode material disclosed in this application includes: Zinc foil as a current collector and its surface active coating layer; The coating layer is a dried product of a slurry applied to the surface of zinc foil; the slurry is formed using an organic solvent, a binder, and an aqueous zinc ion anode material obtained by the above method.

[0019] Optionally, in the slurry, the binder is polyvinylidene fluoride, and the mass ratio of aqueous zinc ion anode material to polyvinylidene fluoride is 7:1 to 10:1.

[0020] Optionally, the drying conditions for the slurry are: vacuum environment, drying temperature of 60℃~80℃, and drying time of 6h~12h.

[0021] This application also discloses the application of the above-mentioned method for preparing aqueous zinc ion anode materials in reducing dendrite growth in aqueous zinc ion batteries. This method involves forming a modification layer on the surface of a zinc foil current collector that promotes uniform nucleation and growth of zinc ions.

[0022] Compared with the prior art, the solution of this application example has the following effects: The preparation method of this application obtains Ti-hybrid metal-organic framework (Ti-MOF) through simple solvothermal synthesis, and then obtains TiO2-hybridized mesoporous nitrogen-doped carbon framework (TM / NC) after heat treatment, and then obtains TM / NC@Zn anode material through coating.

[0023] Because TM / NC has good chemical stability and a high specific surface area (the chemical stability can be verified by the CV curve, and the specific surface area can be verified by the nitrogen adsorption-desorption curve), it can provide more nucleation sites, induce zinc ions to be uniformly deposited on the zinc foil surface (therefore it is not easy to form dendrites; this can be verified by long-term battery cycling), which greatly improves the cycle life of the battery and reduces the occurrence of side reactions.

[0024] Specifically, the hybrid modified mesoporous TM / NC composite coating derived from Ti-MOF can slow down dendrite growth at the anode during battery use and suppress side reactions such as hydrogen evolution, thereby extending the cycle life of the battery.

[0025] Furthermore, the example scheme of this application has at least the following advantages: 1. By modifying the surface of the zinc anode with a layer of MOF hybridized mesoporous composite coating material with high specific surface area and zinc affinity (which can be quantified by wettability and corrosion resistance, and can also be demonstrated by long cycle life), the modified interface can increase ion diffusion kinetics, physically isolate the direct contact between the anode and the electrolyte, and reduce the occurrence of hydrogen evolution reaction and side reactions.

[0026] 2. The method for preparing the anode material in this disclosure is simple to operate and can be used by coating, thereby allowing precise control of the coating thickness.

[0027] 3. The hybrid TM / NC particle structure can achieve a uniform electric field distribution, and the larger specific surface area can ensure uniform deposition of zinc ions, thereby reducing polarization and the zinc nucleation energy barrier, and promoting Zn formation. 2+ Uniform nucleation is essential. Conversely, if nucleation is not uniform, the nuclei will accumulate and protrude, eventually developing into dendrites, which will affect battery life. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 Scanning electron microscope (SEM) of the TM / NC material in Example 1 and the Ti-MOF material in Example 2; Figure 2A The stripping / electroplation of symmetrical cells assembled with zinc electrode sheets in Examples 1 (TM / NC), 2 (Ti-MOF), and Comparative Example 1 (Bare) at a current density of 0.5 mA·cm² was performed. -2 Surface capacity 0.2 mAh·cm -2 Cyclic curves under test conditions; Figure 2B The stripping / electroplation of symmetrical cells assembled with TM / NC in Example 1, Ti-MOF in Example 2, and zinc electrode sheets in Comparative Example 1 (Bare) at a current density of 1 mA·cm -2Surface capacity 1 mAh·cm -2 Cyclic curves under test conditions; Figure 3 Electrochemical impedance (EIS) curves of symmetrical cells assembled with zinc electrode sheets in Examples 1, 2 and Comparative Example 1; Figure 4 Rate performance curves of the full cells in Examples 1, 2 and Comparative Example 1; Figure 5 The charge-discharge cycle curves and cycle efficiency curves of the full cells in Examples 1, 2 and Comparative Example 1 are shown.

[0030] Figure 6 Cyclic voltammetry (CV) curves of the full cells in Examples 1, 2 and Comparative Example 1; Figure 7 The nitrogen adsorption / desorption isotherm of Example 1; Figure 8 The pore size distribution curve is the one corresponding to the nitrogen adsorption / desorption isotherm curve of Example 1. Detailed Implementation

[0031] This application provides a method for preparing a hybrid composite coating derived from a MOF (Metal Organic Framework) on the surface of a zinc anode. The method employs a solvothermal combined with calcination process to obtain a zinc-ion battery anode material with a MOF-derived hybrid composite coating—specifically, a TiO2-modified mesoporous nitrogen-doped carbon framework (TM / NC). This coating can be further coated to obtain a TM / NC@Zn anode material. Here, TM represents Ti / titanium, and M represents MOF.

[0032] Such an anode material has a modified interface, which not only reduces the current density and promotes uniform zinc ion deposition, but also reduces the zinc nucleation overpotential and accelerates ion diffusion, thereby inhibiting dendrite growth and reducing side reactions.

[0033] Furthermore, the surface morphology of the zinc-ion battery anode material is a uniform granular structure. TM / NC has good chemical stability and can provide a large specific surface area and more nucleation sites for the electrode material, thereby promoting the uniform deposition of zinc ions on the zinc foil surface, slowing down dendrite growth, greatly extending the battery life, and reducing the occurrence of battery side reactions (such as dendrite reaction, hydrogen evolution reaction, corrosion passivation, etc.).

[0034] In some examples, specific surface area and pore size analysis (BET) revealed that the particle size of the anode material in the application was mainly concentrated at 40 Å (approximately 4 nm). Furthermore, its nitrogen adsorption-desorption curve exhibited a type IV isotherm with a significant hysteresis loop, which can be used to represent a mesoporous material. Simultaneously, according to BET analysis, the specific surface area of ​​this material can reach 97.36 m². 2 ·g -1 .

[0035] To facilitate the implementation of the example scheme, this application discloses a method for preparing the above-mentioned aqueous zinc ion anode material, and the method includes: calcining a titanium-hybridized metal-organic framework under a vacuum or inert atmosphere, the calcination being sufficient to convert the titanium-hybridized metal-organic framework into a titanium dioxide-hybridized mesoporous nitrogen-doped carbon framework.

[0036] As an example, the titanium-hybridized metal-organic framework was prepared using a solvothermal synthesis method.

[0037] Alternatively, in the solvothermal synthesis of titanium-hybrid metal-organic frameworks, the titanium source reacts with an organic acid ligand via a solvent. Exemplary titanium sources include titanium isopropoxide or tetrabutyl titanate.

[0038] In some examples, the solvent is a mixture of N,N-dimethylformyl and methanol, and the organic acid used as a ligand includes 2-aminoterephthalic acid or terephthalic acid.

[0039] In addition, the calcination method includes: subjecting the titanium-hybridized metal-organic framework to a heat treatment process in an argon atmosphere, heating it from room temperature to 400°C to 600°C at a heating rate of 1°C to 5°C / min and holding it at that temperature.

[0040] More specifically, methods for preparing aqueous zinc ion anode materials include: Step 1: N,N-Dimethylformamide and methanol are mixed at a volume ratio of 1:1 to 2:1 to dissolve terephthalic acid to a concentration of 0.1 mol / L to 0.15 mol / L to form a mixture; then tetrabutyl titanate is mixed with the mixture at a volume ratio of 1:100 to 5:100 under stirring; then the mixture is subjected to a solvothermal reaction in a hydrothermal reactor at 120℃ to 150℃ for 12h to 36h.

[0041] In step 1, the Ti-MOF prepared by the hydrothermal / solvothermal method is used as a precursor in this application. Terephthalic acid can be replaced with 2-aminoterephthalic acid; tetrabutyl titanate can also be replaced with titanium isopropoxide. Furthermore, if the proportion of tetrabutyl titanate in the mixture is outside the above ratios, such as an excess of tetrabutyl titanate, it will reduce the size uniformity of the particles in the material and cause them to become excessively large.

[0042] Step 2: The solvothermal reaction product is successively centrifuged, washed, and dried at 50 ℃~70 ℃ for 8 h~12 h to obtain a titanium-hybridized metal-organic framework. The titanium-hybridized metal-organic framework obtained in Step 2 is a metal complex; taking terephthalic acid as an example, its structure is shown below: The titanium metal ions are complexed with the carbon framework.

[0043] Step 3: The titanium-hybridized metal-organic framework is heated to 400-600°C for a preset time in an argon atmosphere at a heating rate of 1-5°C / min. In this step 3, titanium can combine with oxygen from sources such as N,N-dimethylformamide to form titanium dioxide particles.

[0044] As mentioned above, negative electrode materials can be manufactured using the above materials. Therefore, the example also discloses a negative electrode based on an aqueous zinc ion anode material. This negative electrode includes: a zinc foil as a current collector and an active coating layer on its surface. The coating layer is a dried product of a slurry coated on the surface of the zinc foil; and the slurry is formed using an adhesive and an aqueous zinc ion anode material obtained by performing the above method.

[0045] In this application, the active coating layer can achieve interface protection and protect the zinc foil.

[0046] Specifically, in the slurry, the binder is polyvinylidene fluoride (PVDF), and the mass ratio of aqueous zinc ion anode material to PVDF is 7:1 to 10:1. The PVDF can also be one of the following: methylcellulose, ethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, water-soluble rubber, polyvinyl alcohol, PVDF, and polytetrafluoroethylene. Furthermore, too much binder negatively impacts battery performance, while too little binder may cause the coating on the negative electrode surface to easily detach during the reaction, thus reducing cycle life.

[0047] Optionally, the drying conditions for the slurry are: vacuum environment, drying temperature of 60℃~80℃, and drying time of 6h~12h. Excessive drying temperature will cause cracking on the coating surface, resulting in partial or complete peeling of the coating, while excessively low temperature will affect the smooth volatilization of NMP (N-methylpyrrolidone).

[0048] Furthermore, the example also discloses an application of the method for preparing aqueous zinc ion anode materials in reducing dendrite growth in aqueous zinc ion batteries. This application involves forming a modification layer on the surface of a zinc foil current collector using the method for preparing the aqueous zinc ion anode material, which promotes uniform nucleation and growth of zinc ions.

[0049] The following will provide some more specific embodiments. Example 1 Preparation of negative electrode materials (1) In the preparation process, firstly, 50 ml of N,N-dimethylformamide (DMF) is mixed with 50 ml of methanol to form a solution.

[0050] Subsequently, 12 mmol of terephthalic acid was gradually added to the solution mixture, ensuring it dissolved evenly. Next, 2 ml of tetrabutyl titanate was carefully injected into the solution to avoid a violent reaction.

[0051] Finally, place the mixture on a magnetic stirrer and stir continuously for 30 minutes to ensure that the components are fully mixed and reacted.

[0052] (2) After the solution stirring process is completed, the mixed solution is transferred to the PTFE liner, and then the liner lid is closed and the whole thing is placed into the outer shell of the hydrothermal reactor.

[0053] Next, place the hydrothermal reactor in the electrically heated constant-temperature drying oven, and then start the drying oven. The heating process should be carried out gradually until the temperature inside the drying oven stabilizes at 150 °C, and maintain this temperature for 24 hours to ensure that the reaction in the solution proceeds fully.

[0054] (3) After the drying oven has cooled down, remove the hydrothermal reactor and transfer the mixture inside it to a centrifuge tube.

[0055] Subsequently, the sample was centrifuged in a high-speed centrifuge for 3 minutes. The centrifugation process was repeated 6 times, followed by washing with methanol.

[0056] The centrifuge tubes were then placed in an electrically heated vacuum drying oven at 60°C for 12 hours. After drying, Ti-MOF powder was obtained.

[0057] (4) First, accurately weigh 200 mg of Ti-MOF powder and put it into a pre-prepared porcelain boat.

[0058] Subsequently, the ceramic boat was placed in a tube furnace and calcined using argon as a protective gas. During calcination, the heating rate of the tube furnace was 3 °C / min, and when the temperature reached 600 °C, this temperature was maintained for a total of 4 hours. After calcination, the tube furnace was allowed to cool naturally to room temperature, yielding a mesoporous nitrogen-doped carbon framework decorated with TiO2 nanoparticles. This composite product was named TM / NC.

[0059] (5) Take 180 mg of TM / NC powder and 20 mg of polyvinylidene fluoride (PVDF) powder, put both powders into a mortar and grind them. After grinding, add N-methylpyrrolidone (NMP) dropwise and stir magnetically for 5 h to prepare a slurry. Coat the prepared slurry onto the surface of the zinc anode and vacuum dry at 60℃ for 8 h to obtain the Zn@TM / NC electrode.

[0060] 2. Assemble the battery The prepared zinc anode material was cut into 12mm diameter electrode sheets using a slicer, and two identical electrode sheets were used as the positive and negative electrode sheets.

[0061] Place a cut electrode sheet into the positive electrode shell, with the uncoated side in contact with the positive electrode shell. Place a glass fiber diaphragm in the shell and use a pipette to drop 120 μL of 2M ZnSO4 as the electrolyte. Then place another zinc negative electrode sheet on top of the diaphragm.

[0062] Similarly, the unetched side is brought into contact with the stainless steel gasket, and then the gasket and spring are placed in sequence. Finally, the negative electrode shell is put on, and the battery is sealed using a battery packaging machine to obtain a modified zinc negative electrode aqueous zinc-ion symmetric button battery, marked as Zn@TM / NC / / Zn@TM / NC symmetric battery.

[0063] As above, the prepared material was cut into 12mm diameter electrode sheets using a slicer, and copper foil and Zn@TM / NC were used as the positive and negative electrode sheets.

[0064] Place the copper foil into the positive electrode shell, then place the glass fiber diaphragm inside. Use a pipette to drop 120 μL of 2M ZnSO4 as the electrolyte. Then place another Zn@TM / NC negative electrode sheet on top of the diaphragm.

[0065] Make the uncoated side contact the stainless steel gasket, then put in the gasket and spring in sequence, and put on the negative electrode shell. Use a battery packaging machine to package the battery to obtain a modified Cu / / Zn@TM / NC / / half cell.

[0066] The manganese-based positive electrode, zinc sheet negative electrode, and separator are assembled into the casing, and an electrolyte is injected. The electrolyte is composed of 2M ZnSO4, and the battery is packaged as a Zn@TM / NC / / zinc salt / / manganese-based positive electrode aqueous zinc-ion battery.

[0067] Example 2 1. Preparation of negative electrode materials (1) In the preparation process, firstly, 50 ml of N,N-dimethylformamide (DMF) and 50 ml of methanol were mixed to form a solution. Then, 12 mmol of terephthalic acid was gradually added to this solution mixture to ensure uniform dissolution. Next, 2 ml of tetrabutyl titanate was carefully injected into the solution to avoid vigorous reaction. Finally, the mixture was placed on a magnetic stirrer and stirred continuously for 30 min to ensure that the components were fully mixed and reacted.

[0068] (2) After completing the stirring process of the solution, transfer the mixed solution to a PTFE liner, then ensure that the liner lid is tightly closed, and place the entire assembly into the outer shell of the hydrothermal reactor. Next, place the hydrothermal reactor in an electrically heated constant-temperature drying oven, and then start the drying oven. The heating process should be carried out gradually until the temperature inside the drying oven stabilizes at 150 °C, and maintain this temperature for 24 hours to ensure that the reaction in the solution proceeds fully.

[0069] (3) After cooling in the drying oven, remove the hydrothermal reactor and transfer the mixture inside to centrifuge tubes. Then, centrifuge in a high-speed centrifuge for 3 minutes. Repeat the centrifugation operation 6 times and wash with methanol. Then place the centrifuge tubes in an electric vacuum drying oven at 60°C for 12 hours. After drying, Ti-MOF powder is obtained.

[0070] (5) Take 180 mg of Ti-MOF powder and 20 mg of polyvinylidene fluoride (PVDF) powder, put both powders into a mortar and grind them. After grinding, add N-methylpyrrolidone (NMP) dropwise and stir magnetically for 5 h to prepare a slurry. Coat the prepared slurry onto the surface of the zinc anode and dry it under vacuum at 60℃ for 8 h to obtain a Zn@Ti-MOF electrode.

[0071] 2. Assemble the battery The assembly is the same as in Example 1, except that the negative electrode material is replaced with Ti-MOF.

[0072] Comparative Example 1 1. Preparation of negative electrode materials Cut the zinc foil into 5cm x 5cm sheets, flatten them, and then immerse them in dilute hydrochloric acid (0.1 mol / L) and sonicate for 30 seconds to remove the surface oxide film and impurities. Do not immerse for too long to avoid reducing the thickness of the zinc foil. Remove the sonicated zinc sheets and rinse repeatedly with anhydrous ethanol and deionized water to remove the surface hydrochloric acid. Allow them to air dry naturally. These are then used as unetched bare zinc.

[0073] 2. Assemble the battery The prepared zinc anode material was cut into 12mm diameter sheets using a slicer, with two identical sheets serving as the positive and negative electrodes. One of the cut electrodes was placed in the positive electrode shell, followed by a glass fiber separator. 300µL of 2M ZnSO4 was added as the electrolyte using a pipette, and then another zinc anode sheet was placed on top of the separator. Next, a spacer and a spring were added in sequence, and finally the negative electrode shell was attached. The battery was then sealed using a battery packaging machine, resulting in a modified zinc anode aqueous zinc-ion symmetric button cell, labeled as a Zn / / Zn symmetric button cell.

[0074] As above, the prepared material was cut into 12mm diameter electrode sheets using a slicer. Copper foil and treated zinc foil were used as the positive and negative electrode sheets, respectively. The copper foil was placed in the positive electrode shell, followed by a glass fiber separator. 120µL of 2M ZnSO4 was added as the electrolyte using a pipette. Another zinc negative electrode sheet was then placed on top of the separator. Next, a gasket and a spring were added in sequence, and the negative electrode shell was attached. The battery was then sealed using a battery packaging machine to obtain a modified Cu / / Zn / / half-cell.

[0075] The manganese-based positive electrode, zinc sheet negative electrode, and separator are assembled into the shell, and an electrolyte is injected. The electrolyte is composed of 2M ZnSO4, and the shell is packaged into a Zn / / zinc salt / / manganese-based positive electrode aqueous zinc-ion battery.

[0076] The materials and batteries of Examples 1, 2, and Comparative Example 1 were tested, and the results are as follows: from Figure 1 The SEM scan images show that the TM / NC material particles are uniform in size and have the same morphology.

[0077] Figure 2A and Figure 2B The graphs are cyclic curves for Examples 1, 2 and the comparative example.

[0078] according to Figure 2A and Figure 2B At a current density of 0.5 mA·cm -2 Surface capacity 0.2 mAh·cm -2 Under the test conditions, the bare zinc symmetric cell short-circuited after nearly 100 hours of operation due to the generation of passivation byproducts and hydrogen evolution. The Ti-MOF material showed a similar pattern, operating for less than 100 hours before short-circuiting.

[0079] Compared to Ti-MOF, TM / NC materials exhibit a significantly longer cycle life, exceeding 600 hours. Minimal electrochemical polarization indicates a low nucleation barrier for Zn and highly uniform nucleation.

[0080] Therefore, it can be concluded that after calcination, the TM / NC material exhibits superior cycling performance compared to untreated bare Zn and uncalcined Ti-MOF. (At a current density of 1 mA·cm⁻¹) -2 Surface capacity 1mAh·cm -2 The same conclusion was obtained under the same test conditions.

[0081] Figure 3 The images show symmetrical electrochemical impedance spectroscopy (EIS) curves for the zinc electrode assemblies in Examples 1, 2, and Comparative Example 1. The Zn@TM / NC ||Zn@TM / NC cells exhibit low impedance on the EIS spectrum, demonstrating good charge transfer capability. This further illustrates that the TM / NC material is beneficial for reducing cell resistance.

[0082] Figure 4 Rate performance tests were conducted on three types of full cells at current densities of 0.2, 0.5, 1, 2, and 5 A / g. Zn@TM / NC || V2O5 exhibited good rate performance, indicating that this material possesses excellent stability.

[0083] Figure 5 The stability curves of the batteries after more than 300 cycles at a current density of 1 A / g are shown. The discharge specific capacity of the three batteries all showed a decreasing trend after cycling.

[0084] Initially, the Zn@TM / NC ||V2O5 battery exhibited the highest specific capacity, approximately 210 mAh / g, while the other two batteries had specific capacities of around 180 mAh / g. However, as cycling progressed, both the Zn||V2O5 and Zn@Ti-MOF ||V2O5 batteries showed a rapid decline in capacity, while the Zn@TM / NC||V2O5 battery showed a slower decline.

[0085] In over 300 cycles, both the Zn@TM / NC||V2O5 and Zn||V2O5 batteries exhibited high efficiency, approximately 100%. However, the Zn@Ti-MOF ||V2O5 battery showed a sudden and significant drop in efficiency after just over 100 cycles. When approaching 200 cycles, the efficiency was only around 70%, indicating poor performance. Therefore, ultimately... Figure 5 As can be seen, the Zn@TM / NC||V2O5 battery exhibits excellent cycle stability at a current density of 1 A / g.

[0086] Figure 6The image shown is the CV image of full cells of Zn||V₂O₅, Zn@Ti-MOF||V₂O₅, and Zn@TM / NC||V₂O₅. The scan rate and voltage window are shown below. Figure 6 As shown in the image.

[0087] In-depth analysis of the data revealed consistency in the redox peak characteristics among the three battery types. However, compared to the other two materials, the reduction peak of the Zn@TM / NC battery significantly shifted to a higher potential region, while its oxidation peak noticeably shifted to a lower potential region. This significant shift indicates a weak polarization phenomenon during the redox process. Therefore, the Zn@TM / NC battery is expected to exhibit superior performance.

[0088] Figure 7 and Figure 8 The nitrogen adsorption / desorption isotherms and corresponding pore size distribution curves for Example 1 are shown. The nitrogen adsorption / desorption isotherms measured by a specific surface area analyzer can be used to characterize the specific surface area and pore size distribution of the TM / NC.

[0089] like Figure 7 and Figure 8 As shown, BET measured the TM / NC to have a large specific surface area of ​​97.36 m². 2 g -1 This facilitates electrolyte penetration; the pore size distribution of TM / NC is concentrated at approximately 3.9 nm, exhibiting typical mesoporous characteristics. The uniform pore structure and small pore size effectively reduce the ion concentration gradient on the negative electrode surface, thereby reducing concentration polarization and achieving uniform dissolution and deposition of zinc.

[0090] The above description of the structure, features and effects of this application is based on the embodiments shown in the drawings. The above are only preferred embodiments of this application. However, this application does not limit the scope of implementation to what is shown in the drawings. Any changes made in accordance with the concept of this application, or modifications to equivalent embodiments, that do not exceed the spirit covered by the specification and drawings, should be within the protection scope of this application.

Claims

1. A method for preparing aqueous zinc ion anode materials, characterized in that, include: Under a vacuum or inert atmosphere, titanium-hybridized metal-organic frameworks are calcined, the calcination being sufficient to transform the titanium-hybridized metal-organic frameworks into titanium dioxide-hybridized mesoporous nitrogen-doped carbon frameworks.

2. The method according to claim 1, characterized in that, The titanium-hybridized metal-organic framework was prepared by solvothermal synthesis.

3. The method according to claim 2, characterized in that, In the reaction for preparing titanium-hybrid metal-organic frameworks by solvothermal synthesis, the titanium source reacts with organic acid ligands through a solvent.

4. The method according to claim 3, characterized in that, The solvent is a mixture of N,N-dimethylformyl and methanol, and the organic acid as a ligand includes 2-aminoterephthalic acid or terephthalic acid.

5. The method according to claim 3 or 4, characterized in that, The titanium source includes titanium isopropoxide or tetrabutyl titanate.

6. The method according to claim 1, characterized in that, The calcination method includes: subjecting the titanium-hybridized metal-organic framework to a heat treatment process in an argon atmosphere, heating it from room temperature to 400°C to 600°C at a heating rate of 1°C to 5°C / min and holding it at that temperature.

7. A method for preparing aqueous zinc ion anode materials, characterized in that, The method includes: N,N-dimethylformamide and methanol were mixed at a volume ratio of 1:1 to 2:1 to dissolve terephthalic acid to a concentration of 0.1 mol / L to 0.15 mol / L to form a mixture; then tetrabutyl titanate was mixed with the mixture at a volume ratio of 1 to 5:100 under stirring; then the mixture was subjected to a solvothermal reaction in a hydrothermal reactor at 120°C to 150°C for 12 to 36 hours. The solvothermal reaction product was centrifuged, washed, and dried at 50℃~70℃ for 8h~12h to obtain titanium-hybrid metal-organic frameworks. Additionally, the titanium-hybrid metal-organic framework is heated in an argon atmosphere at a heating rate of 1~5℃ / min to calcine at 400~600℃ for a preset time.

8. A negative electrode based on an aqueous zinc ion anode material, characterized in that, include: Zinc foil as a current collector and its surface active coating layer; The coating layer is a dried product of a paste coated on the surface of zinc foil; The slurry is formed using an organic solvent, a binder, and an aqueous zinc ion anode material obtained by implementing the method according to any one of claims 1 to 7.

9. The negative electrode according to claim 8, characterized in that, In the slurry, the binder is polyvinylidene fluoride, and the mass ratio of aqueous zinc ion anode material to polyvinylidene fluoride is 7:1 to 10:

1. Optionally, the drying conditions for the slurry are: vacuum environment, drying temperature of 60℃~80℃, and drying time of 6h~12h.

10. The application of a method for preparing aqueous zinc-ion anode material according to any one of claims 1 to 7 in reducing dendrite growth in aqueous zinc-ion batteries, characterized in that, The method for preparing aqueous zinc ion anode materials described above forms a modification layer on the surface of a zinc foil current collector that enables uniform nucleation and growth of zinc ions.

Images