Zinc negative electrode with unsaturated molybdenum-based metal oxide solid electrolyte interface layer and preparation and application thereof

Abstract

The invention relates to a zinc negative electrode with an unsaturated molybdenum-based metal oxide solid electrolyte interface layer as well as preparation and application of the zinc negative electrode. The zinc negative electrode comprises a metal zinc matrix and the molybdenum-based oxide solid electrolyte interface layer which is generated on the surface of the metal zinc matrix and contains Mo < 4 + > / Mo < 5 + >. Compared with the prior art, the electrode provided by the invention has good corrosion resistance, the unsaturated molybdenum oxide-based solid electrolyte interface can effectively isolate the contact between the metal zinc electrode and the aqueous electrolyte, the hydrogen evolution side reaction is effectively reduced, and the pH value change on the surface of the electrode is inhibited. And in electrochemical test verification, the electrode shows excellent cycle stability, and does not have dendritic crystal morphology in subsequent scanning electron microscope observation, and the surface of the electrode still keeps flat.

Description

Technical Field

[0001] The present invention belongs to the technical field of zinc ion battery negative electrode materials, and relates to a zinc negative electrode with an unsaturated molybdenum-based metal oxide solid electrolyte interface layer, and the preparation and application thereof. Background Art

[0002] Rechargeable aqueous zinc-ion batteries are an emerging energy technology with high theoretical specific capacity (820 mAh g -1 or 5855mAh cm -3 ), high safety, low cost and environmental friendliness have attracted widespread attention from R&D personnel and major companies.

[0003] Compared with lithium-ion batteries that are prone to explosion accidents due to the use of flammable organic electrolytes, zinc-ion batteries based on aqueous electrolytes have greatly solved this safety problem. However, like many metal materials (lithium, sodium, copper, etc.), zinc metal tends to form dendrites during the electrodeposition process and make the electrode interface no longer flat. During the initial nucleation process, the Zn near the electrode surface 2+ It tends to deposit on metal zinc with the same lattice arrangement. This tendency of zinc ion deposition will aggravate the uneven distribution of ion flux on the electrode surface, resulting in the appearance of many uneven zinc dendrites on the surface of the metal zinc electrode. In addition to the uneven deposition of zinc dendrites at the electrode interface, the passivation problem of the metal zinc electrode surface caused by aqueous electrolytes is also one of the important electrochemical problems that zinc ion batteries need to solve. The parasitic water decomposition side reaction caused by the inherent thermodynamic instability of metal zinc in an aqueous environment is the source of the passivation of the metal zinc electrode. The solvated Zn in the double layer 2+ , it is necessary to overcome the corresponding desolvation energy barrier to desolvate and release a large number of electrochemically active water molecules. The electrochemically active water molecules near the metal zinc electrode are more easily decomposed than the water molecules in the bulk electrolyte, resulting in H + This side reaction generates H₂, which in turn causes a local pH change on the electrode surface. This strongly alkaline environment, created by this side reaction, corrodes the surface of the zinc electrode and forms a passivation layer containing Zn(OH)₂ and ZnO. Therefore, developing a multifunctional solid electrolyte interphase (SEI) is an effective measure to protect the zinc electrode from direct contact with the aqueous electrolyte interface and inhibit the water decomposition side reaction.

[0004] For example, CN202310980734.X provides a preparation and application of a composite zinc anode modified with hydrated molybdenum oxide, using ammonium molybdate solution as the electrolyte to deposit hydrated molybdenum oxide on a zinc sheet. This solution is not only relatively cumbersome to prepare, requiring a constant-voltage electrodeposition device, but also has a relatively short cycle life of only about 200 hours for the symmetrical battery. Furthermore, the provided Zn / / MnO2 full battery has a capacity of almost zero after 200 cycles, resulting in a very low capacity retention rate. Summary of the Invention

[0005] The purpose of the present invention is to provide a zinc negative electrode with an unsaturated molybdenum-based metal oxide solid electrolyte interface layer and its preparation and application. By generating an unsaturated molybdenum oxide-based solid electrolyte interface on the surface of the zinc negative electrode, the metal zinc electrode can be effectively isolated from contact with the aqueous electrolyte, effectively reducing the hydrogen evolution side reaction and inhibiting the pH value change on the electrode surface, greatly improving the thermodynamic stability of the metal zinc electrode, providing a uniform path for the migration of zinc ions, and effectively uniformizing the zinc ion flux on the electrode surface.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] In one aspect, the present invention provides a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer, comprising a metal zinc substrate, and a Mo-containing layer generated on the surface of the metal zinc substrate. 4+ / Mo 5+ Preferably, the molybdenum-based oxide solid electrolyte interface layer is amorphous.

[0008] In a second aspect, the present invention provides a method for preparing a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer, wherein the metal zinc sheet is pretreated and then immersed in an aqueous solution of ammonium molybdate tetrahydrate, and then taken out, cleaned, and dried to obtain a zinc negative electrode.

[0009] Furthermore, the concentration of the aqueous solution of ammonium molybdate tetrahydrate is 6 to 6.5 g / 100 mL.

[0010] Furthermore, the immersion temperature is room temperature, the immersion time is 20 to 40 s, and the corresponding prepared zinc negative electrode is recorded as AMO@Zn (amorphous).

[0011] Furthermore, the immersion temperature is room temperature, the immersion time is 6 to 8 days, and the corresponding prepared zinc negative electrode is recorded as CMO@Zn (crystalline).

[0012] Furthermore, the ratio of the size of the metal zinc sheet to the aqueous solution of ammonium molybdate tetrahydrate is 36πmm 2 :100mL.

[0013] Furthermore, the cleaning and drying process is as follows: cleaning with deionized water and drying in a vacuum drying oven at 60°C.

[0014] Furthermore, the pretreatment process of the metal zinc sheet is: using alcohol ultrasonic cleaning to remove organic impurities that may exist on the surface of the metal zinc sheet, and drying it in a vacuum drying oven at 60°C.

[0015] Furthermore, the aqueous solution of ammonium molybdate tetrahydrate is (NH4)6Mo7O 24 4H2O was dissolved in deionized water at room temperature.

[0016] In a third aspect, the present invention provides an application of a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer, which is used to prepare zinc symmetrical batteries, zinc-copper asymmetric batteries, button aqueous zinc ion batteries or soft-pack aqueous zinc ion batteries, all of which exhibit excellent performance.

[0017] Furthermore, the preparation process of the zinc symmetric battery is as follows:

[0018] a. Cut a 16 mm glass fiber separator and prepare a 2M ZnSO4 aqueous solution as an electrolyte for later use;

[0019] b. Use a CR2032 battery case. Stack the batteries in the following order: negative electrode case → zinc electrode sheet (i.e., AMO@Zn) → fiberglass separator → zinc electrode sheet (AMO@Zn) → gasket → spring → positive electrode case. Then, seal the battery using a battery sealer. Note: When stacking the batteries onto the fiberglass separator, add 120 μL of a 2M ZnSO₄ aqueous solution as the electrolyte.

[0020] Furthermore, the preparation process of the zinc-copper asymmetric battery is as follows:

[0021] a. Cut 16 mm glass fiber separator and Cu foil, and configure 2M ZnSO4 aqueous solution as an electrolyte for standby use;

[0022] b. Weigh 37.3 g of ZnSO4·7H2O, 1.1 g of NaCl, and 1.0 g of H3BO3 and dissolve them in 100 mL of water;

[0023] c. The Cu foil in step a is the working electrode, the Pt sheet is the counter electrode, the saturated calomel electrode is the reference electrode, and the solution in step b is the electrolyte to assemble a three-electrode system;

[0024] d. Using -3mA cm -2 Zn deposition was performed on the Cu foil in the device of step c with a constant current of 100 nm and maintained for 30 min;

[0025] e. After cleaning and drying the Zn@Cu electrode obtained in step d, soak it in (NH4)6Mo7O 24 After 30 seconds in 4H2O aqueous solution, the sample was taken out, washed with deionized water and dried in a vacuum drying oven at 60°C. The sample was labeled AMO@Cu.

[0026] f. Use CR2032 battery cases and stack them in the order: negative electrode case → AMO@Zn → glass fiber separator → AMO@Cu → gasket → spring → positive electrode case. Then, seal the battery using a battery sealer. Note: When stacking onto the glass fiber separator, add 120 μL of 2M ZnSO₄ aqueous solution as the electrolyte.

[0027] Furthermore, the preparation process of the button aqueous zinc ion battery is as follows:

[0028] a. Weigh 1 g of V2O5 and dissolve it in 60 mL of 2 M NaCl aqueous solution at room temperature with stirring, labeled as solution A.

[0029] b. Stir solution A at 30°C for 96 hours;

[0030] c. The product of step b was collected by centrifugation and washed with deionized water. The dark red sample obtained was freeze-dried and stored in argon for standby use. The sample was labeled NVO (NaV3O8·1.5H2O);

[0031] d Weigh 400mg of NVO, 50mg of acetylene black and 50mg of polyvinylidene fluoride, and place them in a mortar and grind them thoroughly;

[0032] e. Add 200 μL of N-methylpyrrolidone to the mixture obtained after grinding in step d, and continue mixing and stirring for 12 h;

[0033] f. Use a pipette to drop 40 μL of the slurry obtained in e onto a 1 × 1 cm 2 The carbon cloth was placed in a vacuum drying oven at 80°C and dried for 12 hours to serve as the positive electrode of aqueous zinc ion batteries.

[0034] g. Cut a 16mm glass fiber separator and prepare a 2M ZnSO4 aqueous solution as an electrolyte;

[0035] h. Use a CR2032 battery case. Stack the batteries in the following order: negative electrode case → AMO@Zn → glass fiber separator → NVO → gasket → spring clip → positive electrode case. Then, seal the batteries using a battery sealer. Note: When stacking the batteries onto the glass fiber separator, add 120 μL of 2M ZnSO₄ aqueous solution as the electrolyte.

[0036] Furthermore, the preparation process of the soft-pack aqueous zinc ion battery is as follows:

[0037] a. Weigh 400mg of NVO, 50mg of acetylene black and 50mg of polyvinylidene fluoride, and place them in a mortar and grind them thoroughly;

[0038] b. Add 200 μL of N-methylpyrrolidone to the mixture obtained after grinding in step a, and continue mixing and stirring for 12 h;

[0039] c. The slurry obtained in step b was applied to the stainless steel electrode using a 20 μm applicator, and then transferred to a vacuum oven at 60°C for drying;

[0040] d. Cut the dried electrode in step c into 8×8cm 2 , while cutting 8×8cm 2 Metal zinc sheet and 10×10cm 2 A glass fiber separator was prepared, and a 2M ZnSO4 aqueous solution was prepared as an electrolyte for standby use;

[0041] e. The soft-pack battery case is constructed using aluminum-plastic film. The negative electrode sheet is stacked in the order of the glass fiber separator, followed by the positive electrode sheet. The sheets are then encapsulated using the aluminum-plastic film and then sealed using a vacuum encapsulator. Note: When stacking the sheets onto the glass fiber separator, ensure that a sufficient amount of 2M ZnSO₄ aqueous solution is filled as the electrolyte.

[0042] It should be pointed out here that the focus of the present invention on the specific preparation process of each battery is to replace the negative electrode sheet with the developed AMO@Zn, etc., and the rest are basically conventional technologies in this field and will not be repeated here.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] (1) The present invention prepares for the first time a solid electrolyte interface layer with an unsaturated molybdenum oxide base to improve the thermodynamic stability and electrochemical performance of a metallic zinc negative electrode. This synthesis method only needs to be carried out at room temperature and the preparation time is extremely short, with the entire preparation process taking only 30 seconds to complete. While significantly reducing energy consumption and time costs, it can also be prepared on a large scale, meeting the requirements of a new generation of low-cost aqueous zinc-ion batteries.

[0045] (2) For example, the AMO@Zn electrode has excellent corrosion resistance. Its amorphous unsaturated molybdenum oxide-based solid electrolyte interface can effectively isolate the metal zinc electrode from the aqueous electrolyte, effectively reducing the hydrogen evolution side reaction and inhibiting the pH change on the electrode surface. In electrochemical testing, the AMO@Zn electrode showed excellent cycling stability, and no dendrite-like morphology was observed in subsequent scanning electron microscopy observations. The AMO@Zn electrode surface remained flat.

[0046] (3) The soft-pack battery with the AMO@Zn electrode as the negative electrode exhibited a stable charge-discharge curve in practical application tests. In continuous charge-discharge tests, the AMO@Zn / / NVO full battery always maintained a stable charge-discharge platform and did not experience short circuits. This soft-pack battery demonstrates that unsaturated molybdenum oxide-based solid electrolyte interfaces can effectively improve the service life of aqueous zinc-ion batteries, providing a path to promote the practical application of aqueous zinc-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1a Optical images of AMO@Zn and CMO@Zn;

[0048] Figure 1b XRD patterns of AMO@Zn and CMO@Zn;

[0049] Figure 1c TEM image of AMO@Zn;

[0050] Figure 1d TEM image of CMO@Zn;

[0051] Figure 1e .Surface SEM image of AMO@Zn;

[0052] Figure 1f .Surface SEM image of CMO@Zn;

[0053] Figure 1g Cross-sectional SEM image of AMO@Zn;

[0054] Figure 1h Cross-sectional SEM image of CMO@Zn;

[0055] Figure 2a Hydrogen evolution reaction tests of AMO@Zn and CMO@Zn;

[0056] Figure 2b .Corrosion resistance testing of AMO@Zn and CMO@Zn;

[0057] Figure 3a Nucleation barrier test of AMO@Cu and CMO@Cu;

[0058] Figure 3b Coulombic efficiency test of AMO@Cu / / AMO@Zn and CMO@Cu / / CMO@Zn batteries;

[0059] Figure 4a .Rate performance test of AMO@Zn and CMO@Zn symmetrical batteries;

[0060] Figure 4b Voltage-capacity curves of AMO@Zn symmetric batteries at different current densities;

[0061] Figure 4c .Voltage-capacity curves of CMO@Zn symmetric batteries at different current densities;

[0062] Figure 4d .Voltage-capacity curves of bare Zn symmetric batteries at different current densities;

[0063] Figure 4e .5mA cm -2 , 1mAh cm -2 Symmetrical battery long cycle performance under test conditions;

[0064] Figure 4f .5mA cm -2 , 1mAh cm -2 SEM image after 600 cycles under test conditions;

[0065] Figure 5a SEM image of NVO;

[0066] Figure 5b .XRD pattern of NVO;

[0067] Figure 5c Cyclic voltammetry curves of aqueous Zn / / NVO full cells;

[0068] Figure 5d Rate performance of aqueous Zn / / NVO full cells;

[0069] Figure 5e .Aqueous Zn / / NVO button cell at 5Ag -1 Long cycle performance under

[0070] Figure 6 .Aqueous Zn / / NVO soft pack battery at 5Ag -1 Long cycle performance under . DETAILED DESCRIPTION

[0071] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0073] The terms "and / or", "or / and", and "and / or" used herein include any one of two or more related listed items, and also include any and all combinations of the related listed items, wherein the any and all combinations include any combination of two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in this application, the technical solution undoubtedly includes technical solutions connected by "logical AND" and technical solutions connected by "logical OR".

[0074] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0075] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0076] Only certain numerical ranges are specifically disclosed herein. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, each individually disclosed point or single value may itself serve as a lower limit or upper limit and be combined with any other point or single value, or with other lower limits or upper limits, to form an unspecified range.

[0077] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows for temperature fluctuations within the precision range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted.

[0078] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc. shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0079] In this application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0080] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0081] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0082] Unless otherwise stated, all formulations and tests herein took place at 25°C.

[0083] As used herein, the terms "comprise," "include," "contain," "have," "have," or other variations thereof are intended to encompass non-exclusive inclusions, and no distinction is made between these terms. The term "comprising" means that other steps and ingredients that do not affect the end result may be added. The compositions and methods / processes of the present invention comprise, consist of, and consist essentially of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. As used herein, no distinction is made between the terms "efficacy," "performance," "effect," and "efficacy."

[0084] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0085] Unless otherwise specified, all steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0086] In the following embodiments, unless otherwise specified, raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art. For example, the preparation process of zinc symmetrical batteries, zinc-copper asymmetrical batteries, button aqueous zinc ion batteries, or soft-pack aqueous zinc ion batteries can be found in the above content.

[0087] Example 1:

[0088] 1. Preparation of AMO@Zn (amorphous) negative electrode

[0089] a. Weigh 6.2g of (NH4)6Mo7O 24 4H2O and dissolve it in 100mL of deionized water at room temperature;

[0090] b. Cut a 12mm diameter zinc sheet and clean any organic impurities on its surface with alcohol ultrasonic cleaning, then dry it in a vacuum drying oven at 60°C.

[0091] c. The dried zinc sheet from step b was immersed in the aqueous solution of ammonium molybdate tetrahydrate prepared in step a for 30 seconds. The sheet was then removed from the solution and rinsed with deionized water and dried in a vacuum drying oven at 60°C. The sample was labeled AMO@Zn.

[0092] 2. Preparation of CMO@Zn (crystalline) anode

[0093] a. Weigh 6.2g of (NH4)6Mo7O 24 4H2O and dissolve it in 100mL of deionized water at room temperature;

[0094] b. Cut a 12mm diameter zinc sheet and clean any organic impurities on its surface with alcohol ultrasonic cleaning, then dry it in a vacuum drying oven at 60°C.

[0095] c. The dried zinc sheet from step b was immersed in the aqueous solution of ammonium molybdate tetrahydrate prepared in step a for 7 days, then removed from the solution, rinsed with deionized water, and dried in a vacuum drying oven at 60°C. The sample was labeled CMO@Zn.

[0096] Material phase characterization

[0097] The crystal structure of the material was analyzed and characterized using a FEI Talos f200x transmission electron microscopy (TEM). The morphology and surface element distribution of the material were characterized using a Hitachi S-4800 scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer. X-ray diffraction patterns (XRD) were measured using Cu Kα radiation on a Bruker D8 Advance diffractometer.

[0098] Characterization of material electrochemical properties

[0099] The positive electrode of the battery under test was prepared by mixing the active material NaV₃O₈·1.5H₂O, the conductive agent acetylene black, and the binder polyvinylidene fluoride in a mass ratio of 8:1:1 in N-methylpyrrolidone to form a slurry. This slurry was then coated onto a carbon cloth current collector. The detailed procedures are described in the preparation process for the aqueous zinc-ion button cell. The mass of active material on each electrode was measured using an electronic balance with a measurement accuracy of 0.01 mg. The linear sweep voltammetry (LSV) curves and corrosion currents of AMO@Zn, CMO@Zn, and ordinary zinc sheets were measured using a three-electrode system under standard atmospheric conditions, using a Pt electrode and a saturated calomel electrode as the counter and reference electrodes, and a 2.0 M sodium sulfate solution (Na₂SO₄) as the electrolyte. The three-electrode system and the cyclic voltammetry curves of the aqueous zinc-ion button cell were measured at room temperature on a CHI 760E electrochemical workstation. In addition, the coulombic efficiency test of zinc-copper asymmetric batteries, the rate performance test and long cycle test of zinc symmetric batteries, and the long cycle test of aqueous zinc-ion button batteries and soft-pack batteries were all carried out at room temperature on the LAND test system.

[0100] Phase characterization of AMO@Zn

[0101] Figure 1a Optical photos of AMO@Zn and CMO@Zn are shown. The surface of the AMO@Zn electrode appears golden after rapid immersion, while the surface of the CMO@Zn electrode appears black after long-term immersion. Figure 1b The XRD patterns of AMO@Zn and CMO@Zn are shown. AMO@Zn does not show any other characteristic peaks except the XRD characteristic peaks of metallic zinc, indicating that its molybdenum-based oxide coating is an amorphous structure; while the XRD characteristic peaks of CMO@Zn indicate that the molybdenum-based oxide coating on the surface of metallic zinc belongs to the unsaturated molybdenum-based oxide Mo 13 O 33(PDF#13-0345) To further verify the structure of the molybdenum oxide-based SEI, the present invention conducted TEM measurements on the coating. Figure 1c As shown, the TEM image of AMO@Zn shows that the coating has no obvious lattice fringes; Figure 1d The lattice fringes with a spacing of 1.1 nm in the CMO@Zn image shown correspond to Mo 13 O 33 (010) crystal plane. In summary, the XRD patterns and TEM images simultaneously prove the amorphous SEI structure of AMO@Zn and the crystalline SEI structure of CMO@Zn. In addition, Figure 1e and Figure 1f The surface micromorphologies of AMO@Zn and CMO@Zn are shown respectively. Figure 1g It shows that the coating thickness of AMO@Zn is 241nm. As the immersion time increases, Figure 1h The coating thickness of the demonstrated CMO@Zn increased to 1.72 μm.

[0102] Thermodynamic stability of AMO@Zn

[0103] Figure 2a The hydrogen evolution test curves of AMO@Zn, CMO@Zn and ordinary zinc electrodes are shown. As can be seen from the figure, the hydrogen evolution potential of AMO@Zn and CMO@Zn electrodes is much higher than that of ordinary zinc electrodes, indicating that the unsaturated molybdenum-based oxide coating effectively inhibits the parasitic hydrogen evolution reaction of the metal zinc electrode under aqueous conditions. In addition, the present invention also conducts corrosion resistance tests on AMO@Zn, CMO@Zn and ordinary zinc electrodes. Figure 2b As shown, both the AMO@Zn and CMO@Zn electrodes exhibited corrosion voltages significantly higher than those of conventional zinc electrodes and corrosion current densities significantly lower than those of conventional zinc electrodes. These results indicate that both AMO@Zn and CMO@Zn electrodes exhibit excellent corrosion resistance in aqueous electrolytes. In summary, metallic zinc electrodes with unsaturated molybdenum-based oxide SEIs possess excellent thermodynamic stability.

[0104] Electrochemical stability of AMO@Zn

[0105] Figure 3a The nucleation overpotential curve of Zn / / Cu asymmetric battery is shown, in which the nucleation energy barrier of AMO@Cu is the smallest, indicating that the zinc ion deposition resistance of amorphous unsaturated molybdenum-based oxide SEI is smaller than that of crystalline molybdenum-based oxide SEI and ordinary metal-based electrodes without any modification. Figure 3bFurther long-term coulombic efficiency testing revealed that the AMO@Cu system also exhibited long cycle life and high average coulombic efficiency. The Zn / / Cu asymmetric battery test data demonstrates the enhanced electrochemical stability of the amorphous unsaturated molybdenum-based oxide SEI. For further characterization, the present invention employed high current testing on the Zn / / Zn symmetric battery system.

[0106] Figure 4a The rate performance of the Zn / / Zn symmetric battery is shown. It is worth noting that with the continuous increase of current density, the AMO@Zn symmetric battery always maintains the lowest polarization voltage, which is consistent with the results of the Figure 3a The test results are consistent with those of the previous study; moreover, the AMO@Zn symmetric battery also exhibits the longest cycle life, which is also consistent with the results of Figure 3b The test results remain consistent. Figure 4b -d shows the details of the voltage-capacity curves of AMO@Zn, CMO@Zn and ordinary zinc symmetric batteries respectively. Figure 4e The Zn / / Zn symmetric battery was demonstrated at 5 mA cm -2 The long cycle life at the current density is 2.5 times that of the Zn@AMO@Zn symmetrical battery, which shows an excellent cycle stability of over 4000h. Moreover, the SEM image of the AMO@Zn electrode after cycling is shown in Figure 2. Figure 4f As shown in Figure 3, the SEM image results show that the surface of the AMO@Zn electrode remains smooth and no dendrite-like morphology is observed. In summary, the amorphous unsaturated molybdenum-based oxide SEI can effectively improve the cycling stability of the metal zinc electrode.

[0107] Practical application of AMO@Zn in aqueous zinc-ion batteries

[0108] Figure 5a and Figure 5b The SEM image and XRD pattern of NVO (NaV3O8·1.5H2O) are shown respectively. The micromorphology of NVO presents a spindle-shaped structure, and its crystal structure belongs to PDF#16-0601. Figure 5c The cyclic voltammetry curves of the aqueous Zn / / NVO full cell are shown. Compared with the cyclic voltammetry curves based on ordinary zinc electrodes, the AMO@Zn / / NVO full cell does not show other redox peaks, indicating that the amorphous unsaturated molybdenum-based oxide SEI does not cause other side reactions; moreover, the polarization of the amorphous unsaturated molybdenum-based oxide SEI is reduced, indicating an improvement in the electrochemical reaction rate. Figure 5d The demonstrated full-cell rate performance shows the good tolerance of the amorphous unsaturated molybdenum-based oxide SEI at different current densities; among them, the cycle retention rate of the AMO@Zn / / NVO battery at the return low current density is also higher than that of the ordinary Zn / / NVO battery.

[0109] Figure 5e Demonstrated the performance of aqueous Zn / / NVO button cells at 5Ag -1 The long cycle curve under the AMO@Zn / / NVO full battery shows a cycle stability of 85.8%, while the ordinary Zn / / NVO full battery short-circuits after 1500 cycles and has a cycle stability of 59.2%. This is closer to practical applications. Figure 6 Demonstrated aqueous Zn / / NVO soft-pack full-cell performance at 5Ag -1 The long-cycle curve under 100 nm shows that the AMO@Zn / / NVO soft-pack full-cell has a cycling stability of 93.4%, while the conventional Zn / / NVO full-cell short-circuits after 400 cycles and has a cycling stability of 63.6%. In summary, the metallic zinc anode with an amorphous unsaturated molybdenum-based oxide SEI has superior electrochemical performance.

[0110] Comparative Example 1:

[0111] Compared with the AMO@Zn negative electrode in Example 1, most of the parts are the same, except that the metal zinc sheet is immersed in a three-electrode system with "ammonium molybdate tetrahydrate aqueous solution" as the deposition electrolyte for electrodeposition treatment. The three-electrode system uses a calomel electrode as the reference electrode, a Pt sheet as the counter electrode, and a zinc sheet as the working electrode, and then electrodeposits for 30 seconds at a constant potential (-1.0 V).

[0112] Analysis shows that electrodes prepared by deposition with an applied voltage are not effective because they thicken the SEI layer of molybdenum-based oxides on the electrode surface, increasing the energy barrier for zinc ion migration at the SEI interface and negatively impacting the battery's cycling performance. The SEI layer of the metallic zinc negative electrode in aqueous zinc batteries requires not only stability in aqueous electrolytes but also a minimal thickness.

[0113] Taking CN202310980734.X as an example, in addition to the need to provide a constant voltage electrodeposition device (i.e., more energy) during the preparation process, the prior art also has the following defects in performance: 1. The symmetrical battery cycle life shown in CN202310980734.X is 200h, while the present invention can achieve a cycle life of more than 4000h; 2. When the Zn / / MnO2 full battery shown in CN202310980734.X is stable to 200 cycles, the battery capacity is almost 0, and the capacity retention rate is very low; while the Zn / / NVO full battery provided by the present invention has a cycle life of more than 4000h at 5Ag. -1 At a current density of 1.5 GHz, the cycle retention rates of 85.8% (2000 cycles, button battery) and 93.4% (500 cycles, soft pack battery) are still maintained.

[0114] Technical Summary

[0115] This invention provides a cost-effective, industrially compatible method for converting common commercial zinc foil into an aqueous zinc-ion battery anode suitable for long-term energy storage. By constructing an amorphous, unsaturated molybdenum-based oxide SEI on the zinc surface via chemical bath deposition, the AMO@Zn anode addresses the critical reaction interface problem in zinc anodes. Based on the above experimental results, the AMO@Zn exhibits the following advantages: 1. Enhanced ion transfer kinetics; 2. Mitigated electrochemical parasitic reactions and improved corrosion resistance of the zinc metal anode in weakly acidic aqueous electrolytes; and 3. The amorphous, unsaturated molybdenum-based oxide SEI suppresses zinc dendrite growth, resulting in a smoother zinc electrodeposition process. Thanks to these characteristics, the strategy of constructing an amorphous, unsaturated molybdenum-based oxide SEI on the zinc metal anode has a positive impact on the performance of both symmetric cells and full cells for practical applications, resulting in superior long-term cycling stability, high capacity retention, and a smoother deposition surface. This provides a new design solution for the preparation of highly stable aqueous zinc-ion batteries.

[0116] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer, characterized in that: It includes a metal zinc matrix and a Mo-containing 4+ / Mo 5+ Molybdenum-based oxide solid electrolyte interface layer.

2. The method for preparing a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer according to claim 1, wherein: The metal zinc sheet is pretreated and then immersed in an aqueous solution of ammonium molybdate tetrahydrate, and then taken out, cleaned, and dried to obtain a zinc negative electrode.

3. The method for preparing a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer according to claim 2, characterized in that: The concentration of the aqueous solution of ammonium molybdate tetrahydrate is 6-6.5 g / 100 mL.

4. The method for preparing a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer according to claim 2, characterized in that: The soaking temperature is room temperature and the soaking time is 20 to 40 seconds.

5. The method for preparing a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer according to claim 2, characterized in that: The soaking temperature is room temperature and the time is 6 to 8 days.

6. The method for preparing a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer according to claim 2, characterized in that: The ratio of the size of the metal zinc sheet to the aqueous solution of ammonium molybdate tetrahydrate is 36πmm 2 :100mL.

7. The method for preparing a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer according to claim 2, characterized in that: The cleaning and drying process is as follows: cleaning with deionized water and drying in a vacuum drying oven at 60°C.

8. The method for preparing a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer according to claim 2, characterized in that: The pretreatment process of the metal zinc sheet is as follows: using alcohol ultrasonic cleaning to remove organic impurities that may exist on its surface, and drying it in a vacuum drying oven at 60°C.

9. The method for preparing a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer according to claim 2, characterized in that: The aqueous solution of ammonium molybdate tetrahydrate adopts (NH4)6Mo7O 24 4H2O was dissolved in deionized water at room temperature.

10. The use of a zinc negative electrode having an unsaturated molybdenum-based metal oxide solid electrolyte interface layer according to claim 1, characterized in that: The zinc negative electrode is used to prepare a zinc symmetrical battery, a zinc-copper asymmetrical battery, a button aqueous zinc ion battery or a soft-pack aqueous zinc ion battery.

Images