Modified zinc powder negative electrode based on phase change material, preparation method thereof and aqueous zinc ion battery

Abstract

This application relates to the field of new energy technology, and in particular to a zinc powder anode modified with phase change materials, its preparation method, and an aqueous zinc-ion battery. The zinc powder anode modified with phase change materials includes: a current collector; and an anode active material layer disposed on at least one surface of the current collector. The anode active material layer includes anode active material, which comprises zinc powder and copper oxalate. The introduction of copper oxalate as the anode active material induces interfacial structural reconstruction and local coordination environment evolution during electrochemical processes, improving nucleation behavior and interfacial stability during zinc deposition / stripping, reducing hydrogen evolution side reactions, and enhancing the reversibility of zinc deposition / stripping; thereby improving the cycle stability of the aqueous zinc-ion battery. This anode material is readily available, the process is simple, and it has good compatibility with existing zinc powder anode slurry coating processes, showing promising application prospects.

Description

Technical Field

[0001] This application relates to the field of new energy technology, and in particular to a zinc powder anode based on phase change material modification, its preparation method, and an aqueous zinc-ion battery. Background Technology

[0002] Aqueous zinc-ion batteries are considered a promising energy storage system due to their high safety, low cost, wide availability of raw materials, and environmental friendliness. The anode, a key component of aqueous zinc-ion batteries, directly affects the battery's polarization behavior, coulombic efficiency, and cycle life due to its interfacial stability. Current research often uses Zn foil as the anode, but the utilization rate of Zn foil in the entire cell is low, and there are limitations in terms of large-scale processing and cost control. In contrast, zinc powder anodes offer advantages such as flexible film formation methods, ease of coating processing, and scalable fabrication, making them a potential alternative to Zn foil.

[0003] However, zinc powder anodes, especially particle-stacking zinc powder anodes, are more prone to problems such as uneven local current density, uneven nucleation, dendrite growth, hydrogen evolution side reactions, and byproduct accumulation during deposition / stripping, leading to intensified interfacial polarization, decreased reversibility, and shortened cycle life. Existing research has largely focused on improving the stability of zinc anodes through electrolyte additives, surface coatings, or current collector structure control. However, solutions for introducing interfacial control components at the active material level and ensuring compatibility with existing slurry coating processes remain relatively limited. In particular, there is a lack of composite active material designs that balance process simplicity, high-rate adaptability, and high-temperature stability. Summary of the Invention

[0004] Therefore, the purpose of this application is to overcome the shortcomings of the prior art and provide a zinc powder anode modified with phase change materials, its preparation method, and an aqueous zinc-ion battery. This addresses the problems of uneven local current density, uneven nucleation, dendrite growth, hydrogen evolution side reactions, and byproduct accumulation that easily occur in traditional zinc powder anodes during deposition / stripping, leading to intensified interfacial polarization, decreased reversibility, and shortened cycle life of aqueous zinc-ion batteries.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] First, this application provides a zinc powder anode based on phase change material modification, comprising:

[0007] Current collector; and,

[0008] A negative electrode active material layer is disposed on at least one side surface of the current collector. The negative electrode active material layer includes a negative electrode active material, which includes zinc powder and copper oxalate.

[0009] Preferably, the mass ratio of zinc powder to copper oxalate is 90~98:1~8.

[0010] Preferably, based on the total weight of the negative electrode active material layer, the mass content of copper oxalate is 1% to 10%. More preferably, the mass content of copper oxalate is 1% to 5%; more preferably, the mass content of copper oxalate is 2%. Within the above range, copper oxalate can effectively participate in local interface regulation without significantly affecting the effective reaction area and transport process of the zinc negative electrode due to an excessively high proportion of inactive components.

[0011] Preferably, the zinc powder can be at least one of flake zinc powder, quasi-flake zinc powder, irregular granular zinc powder, and spherical granular zinc powder. More preferably, the zinc powder is flake zinc powder, which has better coating processability and layer overlap characteristics, which is beneficial for forming a continuous negative electrode active layer and can alleviate the problem of local current concentration in particle-stacking negative electrodes to a certain extent.

[0012] Preferably, the average particle size of the flake zinc powder is 1~100μm, more preferably 5~50μm, and even more preferably 10~30μm.

[0013] Preferably, the aspect ratio of the zinc powder is 40-80, more preferably 45-75, and even more preferably 65-70.

[0014] Preferably, copper oxalate is dispersed on all or part of the outer surface of the flake zinc powder particles; or, copper oxalate is dispersed between the flake zinc powder particles; or, some copper oxalate is dispersed on all or part of the outer surface of the flake zinc powder particles, and some copper oxalate fills between the flake zinc powder particles.

[0015] Preferably, the active material layer further includes a binder; the binder is selected from one or more of polyvinylidene fluoride, polyacrylonitrile, polyimide and perfluorosulfonic acid ionomer.

[0016] Preferably, the mass content of the binder is 1% to 5% based on the total weight of the negative electrode active material layer.

[0017] Preferably, the current collector is selected from copper foil, titanium foil, stainless steel foil, or stainless steel mesh.

[0018] Based on a general inventive concept, this application also provides a method for preparing a zinc powder anode modified with phase change material, comprising the following steps:

[0019] S1. Mix and grind zinc powder, copper oxalate and binder, then add organic solvent to form a slurry;

[0020] S2. The slurry is coated on at least one side of the current collector and then dried to obtain a zinc powder anode based on phase change material modification.

[0021] Preferably, the mass ratio of zinc powder, copper oxalate, and binder is 90~98:1~8:1~5. More preferably, it is 94~98:1~3:1~3, and even more preferably, it is 96:2:2.

[0022] Preferably, the purity of copper oxalate is 95% or higher, and more preferably 99% or higher.

[0023] Preferably, the organic solvent is selected from one or more of N-methylpyrrolidone, methyl vinyl ketone, dichloromethane, and ethanol.

[0024] Preferably, the current collector is selected from copper foil, titanium foil, stainless steel foil, or stainless steel mesh.

[0025] Preferably, the drying temperature is 50~60℃.

[0026] Based on a general inventive concept, this application also provides an aqueous zinc-ion battery, which includes the above-mentioned zinc powder negative electrode based on phase change material modification.

[0027] Preferably, the aqueous zinc-ion battery can be a full cell, a half cell, or a symmetrical cell.

[0028] Preferably, the aqueous zinc-ion battery includes a positive electrode, a negative electrode, an electrolyte, and a separator; wherein the negative electrode is the aforementioned zinc powder negative electrode based on phase change material modification; the positive electrode includes a positive electrode active material, which includes at least one of vanadium-based materials, manganese-based materials, and Prussian blue positive electrode materials; the electrolyte is an aqueous solution of zinc salt; and the separator is glass fiber.

[0029] Preferably, the vanadium-based material includes V2O5.

[0030] Preferably, the zinc salt is at least one of zinc sulfate, zinc chloride, zinc acetate, and zinc trifluoromethanesulfonate.

[0031] Preferably, the concentration of Zn ions in the electrolyte is 0.5~5 mol / L.

[0032] The technical solution of this application utilizes an interface regulation mechanism driven by electrochemical phase transition:

[0033] By introducing copper oxalate as a functional matrix, the in-situ transformation of the C=O bond and the dynamic evolution of the copper valence state trigger a profound reconstruction (phase transition) of the interfacial coordination environment. This transformation effectively reconstructs the interactions between water molecules, zinc ions, and the electrode surface (local coordination environment reconstruction). The resulting interfacial coordination reconstruction leads to a more uniform distribution of Zn-O interaction sites, enhances local zinc affinity, and simultaneously modulates the Zn... 2+ The interface behavior of Zn and H2O. 2+The adsorption and desolvation processes are more spatially uniform, and the interfacial energy fluctuations and polarization accumulation are alleviated. Compared with side reactions, the selectivity of the interface for zinc deposition is significantly improved, thereby suppressing side reactive hydrogen evolution and guiding uniform zinc deposition.

[0034] Compared with the prior art, this application has the following beneficial effects:

[0035] This application constructs a composite anode active material by combining copper oxalate and zinc powder, and then prepares a zinc powder anode based on phase change material modification using this active material. When this phase change material-modified zinc powder anode is applied to an aqueous zinc-ion battery, copper oxalate undergoes a phase change and continuously induces interfacial structure reconstruction and local coordination environment evolution, dynamically optimizing zinc ion adsorption, desolvation, and deposition behavior, significantly improving nucleation uniformity, and suppressing hydrogen evolution and interfacial instability. Based on this mechanism, the prepared anode exhibits reduced nucleation overpotential and corrosion tendency in the half-cell. In specific aqueous zinc-ion batteries, the symmetrical cells achieve stable cycle life far exceeding that of the unmodified zinc powder anode at different current densities; the half-cell exhibits high coulombic efficiency and a significantly increased cycle count; and the full cell combines excellent high-rate adaptability with high-temperature stability, maintaining high capacity after cycling.

[0036] Meanwhile, the raw materials of this invention are widely available and the preparation is simple. It is also well compatible with existing electrode slurry coating routes and has significant prospects for promotion. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0038] Figure 1 Linear sweep voltammetry curves of ZP@CuC2O4 provided in Example 1 and ZP provided in Comparative Example 1.

[0039] Figure 2 The Zn∥Zn symmetric cells corresponding to the ZP@CuC2O4 provided in Example 1 and the ZP provided in Comparative Example 1 were tested at 25°C and 1 mA cm⁻¹. -2 / 1mAh cm -2 Voltage-time cycle curve under the given conditions.

[0040] Figure 3 Zn∥Zn symmetric cells corresponding to the ZP@CuC₂O₄ provided in Examples 1, 2, 3, and 4, and the ZP provided in Comparative Example 1, were tested at 25°C and 0.5 mA cm⁻¹. -2 / 0.25mAh cm -2 Voltage-time cycle curves under the given conditions. Figure 3 a is the voltage-time cycle curve of the Zn∥Zn symmetrical cell corresponding to ZP provided in Comparative Example 1; Figure 3 b~ Figure 3 e represents the voltage-time cycle curves of Zn∥Zn symmetric cells corresponding to ZP@CuC2O4 provided in Examples 2, 1, 3, and 4.

[0041] Figure 4 Zn∥Zn symmetric cells corresponding to the ZP@CuC₂O₄ provided in Examples 1, 2, 3, and 4, and the ZP provided in Comparative Example 1, were tested at 25°C and 5 mA cm⁻¹. -2 / 1mAh cm -2 Voltage-time cycle curves under the given conditions. Figure 4 a is the voltage-time cycle curve of the Zn∥Zn symmetrical cell corresponding to ZP provided in Comparative Example 1; Figure 4 b~ Figure 4 e represents the voltage-time cycle curves of Zn∥Zn symmetric cells corresponding to ZP@CuC2O4 provided in Examples 2, 1, 3, and 4.

[0042] Figure 5 Zn∥Zn symmetric cells corresponding to ZP@CuC₂O₄ provided in Examples 1, 2, 3, and 4, and ZP provided in Comparative Example 1, were tested at 25°C and 7 mA cm⁻¹. -2 / 1mAh cm -2 Voltage-time cycle curves under the given conditions. Figure 5 a is the voltage-time cycle curve of the Zn∥Zn symmetrical cell corresponding to ZP provided in Comparative Example 1; Figure 5 b~ Figure 5 e represents the voltage-time cycle curves of the Zn∥Zn symmetric cells corresponding to ZP@CuC2O4 provided in Examples 2, 1, 3, and 4.

[0043] Figure 6 The Zn∥Zn symmetric cells corresponding to the ZP@CuC₂O₄ provided in Example 1 and the ZP provided in Comparative Example 1 were tested at 40°C and 0.5 mA cm⁻¹. -2 / 0.25mAh cm -2 Voltage-time cycle curve under the given conditions.

[0044] Figure 7 The in-situ EIS comparison diagrams of the ZP@CuC2O4 provided in Example 1 and the ZP corresponding to the Zn∥Zn symmetric cell provided in Comparative Example 1 are shown.

[0045] Figure 8 The morphology and elemental distribution of ZP@CuC2O4 and ZP corresponding to ZP in Example 1 and Comparative Example 1, respectively, before cycling are shown in the following figures: Figure 8 a is the SEM image of the ZP anode. Figure 8 b、 Figure 8 c. Figure 8 d represents the EDS distribution of Cu, Zn, and O elements, respectively. Figure 8 e is a SEM image of ZP@CuC2O4. Figure 8 f、 Figure 8 g、 Figure 8 h represents the EDS distribution of Cu, Zn, and O elements.

[0046] Figure 9 The Zn∥Zn symmetric cells corresponding to the ZP@CuC2O4 provided in Example 1 and the ZP provided in Comparative Example 1 were measured at 1 mA / cm². -2 / 1mAh cm -2 The morphology and elemental distribution of ZP@CuC2O4 and ZP are shown in the following figures after 100 cycles under the specified conditions. Figure 9 a is the SEM image of the ZP anode after 100 cycles. Figure 9 b、 Figure 9 c. Figure 9 d represents the EDS distribution of Cu, Zn, and O elements, respectively. Figure 9 e is the SEM image of the ZP@CuC2O4 anode after 100 cycles. Figure 9 f、 Figure 9 g、 Figure 9 h represents the EDS distribution of Cu, Zn, and O elements.

[0047] Figure 10 Tafel diagrams of Zn∥Zn symmetric cells corresponding to ZP@CuC2O4 provided in Example 1 and ZP provided in Comparative Example 1.

[0048] Figure 11 The overpotential curves of the half-cells corresponding to ZP@CuC2O4 provided in Example 1 and ZP provided in Comparative Example 1 are shown.

[0049] Figure 12 Zn∥V₂O₅ full cells constructed from ZP@CuC₂O₄ prepared in Example 1 and ZP prepared in Comparative Example 1 were tested at 25 °C and 15 A g. -1 Cyclic performance under certain conditions.

[0050] Figure 13Zn∥V₂O₅ full cells constructed from ZP@CuC₂O₄ prepared in Example 1 and ZP prepared in Comparative Example 1 were tested at 40 °C and 7 A g. -1 Cyclic performance under certain conditions.

[0051] Figure 14 The pouch cell constructed from ZP@CuC2O4 prepared in Example 1 was tested at 7 A g. -1 Cyclic performance at current density.

[0052] Figure 15 The image shows a test image of a pouch cell battery constructed using ZP@CuC2O4 prepared in Example 1, which illuminates an electronic watch. Detailed Implementation

[0053] The embodiments described in this specification are merely for explaining this application and are not intended to limit this application.

[0054] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0055] Those skilled in the art will understand that the order in which the steps are written in the various embodiments or examples does not imply a strict execution order and does not limit the implementation process in any way. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but sequentially is preferred.

[0056] In this application, "normal temperature" refers to 25°C.

[0057] The present application is further illustrated below with reference to embodiments. It should be understood that these embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0058] In the following examples, the zinc powder is commercially available flake zinc powder; the average particle size is 20 μm; and the aspect ratio is 70.

[0059] Example 1

[0060] The raw materials were weighed according to the mass ratio of zinc powder, copper oxalate and polyvinylidene fluoride of 96:2:2, with a total mass of 0.6g. After being mixed evenly, they were ground. Then, 1.8mL of N-methylpyrrolidone was added and dispersed to prepare a slurry, which was then coated on the surface of copper foil and dried overnight under vacuum at 55℃ to obtain a zinc powder anode based on phase change material modification, denoted as ZP@CuC2O4.

[0061] Example 2

[0062] The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of zinc powder, copper oxalate and polyvinylidene fluoride is different. In this embodiment, the mass ratio of zinc powder, copper oxalate and polyvinylidene fluoride is 97:1:2; the other operations and parameters are the same as those in Example 1.

[0063] Example 3

[0064] The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of zinc powder, copper oxalate and polyvinylidene fluoride is different. In this embodiment, the mass ratio of zinc powder, copper oxalate and polyvinylidene fluoride is 93:5:2; the other operations and parameters are the same as those in Example 1.

[0065] Example 4

[0066] The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of zinc powder, copper oxalate and polyvinylidene fluoride is different. In this embodiment, the mass ratio of zinc powder, copper oxalate and polyvinylidene fluoride is 90:8:2; the other operations and parameters are the same as those in Example 1.

[0067] Comparative Example 1

[0068] The raw materials were weighed at a mass ratio of zinc powder to polyvinylidene fluoride of 98:2, with a total mass of 0.6g. After being mixed evenly, the mixture was ground. Then, 1.8mL of N-methylpyrrolidone was added to disperse the mixture and a slurry was prepared. This slurry was then coated onto the surface of a copper foil and dried overnight under vacuum at 55℃ to obtain a zinc powder negative electrode, denoted as ZP.

[0069] Performance testing:

[0070] Linear sweep voltammetry (LSV) testing: A three-electrode system was used, with a ZP or ZP@CuC2O4 electrode as the working electrode, a platinum sheet as the counter electrode, an Ag / AgCl electrode as the reference electrode, and a 2 mol / L ZnSO4 aqueous solution as the electrolyte. Testing was performed at room temperature using an Ivium electrochemical workstation at a scan rate of 10 mV / s. -1 .

[0071] Figure 1 The linear sweep voltammetry (LSV) curves of the ZP@CuC2O4 anode provided in Example 1 and the ZP anode provided in Comparative Example 1 show that the cathode current of the ZP@CuC2O4 electrode is significantly reduced in the negative potential region, which confirms that the ZP@CuC2O4 anode effectively suppresses hydrogen evolution.

[0072] The following are examples of the application and performance testing of the aforementioned zinc powder anode in aqueous zinc-ion batteries:

[0073] Application Example 1

[0074] Preparation of Zn∥Zn symmetric cells:

[0075] The negative electrodes prepared in each embodiment and comparative example were used as the working electrode and counter electrode of the symmetric cell, respectively. A 2mol / L ZnSO4 aqueous solution was used as the electrolyte and glass fiber was used as the separator to assemble a 2025 type button zinc ion symmetric cell (i.e., Zn∥Zn symmetric cell).

[0076] Performance testing:

[0077] 1. Constant current charge-discharge test at room temperature (25℃): The assembled Zn∥Zn symmetric battery was subjected to constant current charge-discharge tests under four different electrochemical conditions. Condition 1 was 0.5 mA cm⁻¹. -2 / 0.25mAh cm -2 Condition 2 is 5mAcm -2 / 1mAh cm -2 Condition 3 is 7mA cm -2 / 1mAh cm -2 Condition 4 is 1mA cm -2 / 1mAh cm -2 For each condition, deposition and stripping were performed at the corresponding current density until the battery voltage polarization suddenly increased or short-circuited, and the cycle life (in hours) under each condition was recorded; the results are shown in Table 1 below.

[0078] 2. Constant current charge-discharge test under high temperature (40℃): The assembled Zn∥Zn symmetrical battery was subjected to a constant current charge-discharge test at 0.5 mA / cm². -2 / 0.25mAh cm -2 Under constant current charge-discharge conditions, deposition and stripping are performed at this current density until the battery voltage polarization suddenly increases or short circuit failure occurs, and its cycle life is recorded.

[0079] 3. In-situ EIS (Electrochemical Impedance Spectroscopy) Testing: In-situ EIS testing was performed using a Zn∥Zn symmetrical cell. After assembly, the cell was allowed to stand for 3 hours before being connected to a Gamry electrochemical workstation. During the test, the cell was first subjected to constant current discharge, and the EIS was measured every 3 minutes for 20 consecutive tests. Subsequently, the cell was subjected to constant current charging, and the EIS was measured every 3 minutes for 20 consecutive tests. The results were used to evaluate the interfacial impedance evolution of the negative electrode during the zinc deposition / stripping process.

[0080] 4. Morphology and elemental distribution analysis of the negative electrode material: (The analysis will be conducted at 1 mA cm⁻¹) -2 / 1mAh cm -2 The Zn∥Zn symmetric cell was disassembled after 100 cycles under the specified conditions. The negative electrode was removed, and the surface residual electrolyte was gently washed with deionized water and allowed to air dry. The surface morphology of the negative electrode was observed using scanning electron microscopy (SEM), and the elemental distribution was analyzed by energy dispersive spectroscopy (EDS).

[0081] 5. Tafel Curve Testing: Tafel curve testing was performed using Zn∥Zn symmetrical cells. Symmetrical cells were assembled with ZP or ZP@CuC₂O₄ electrodes, respectively. The electrolyte was a 2 mol / L ZnSO₄ aqueous solution. Testing was conducted at room temperature using an Ivium electrochemical workstation at a scan rate of 50 mV / s. -1 .

[0082] Table 1 Cycle life of Zn∥Zn symmetric cells at 25℃

[0083]

[0084] Figures 3-5 The Zn∥Zn symmetric cells corresponding to ZP@CuC2O4 provided in Examples 1-4 and ZP provided in Comparative Example 1 were tested at 25°C and 0.5 mA cm⁻¹. -2 / 0.25mAh cm -2 5mA cm -2 / 1mAh cm -2 and 7mA cm -2 / 1mAh cm -2Voltage-time cycling curves under the specified conditions are shown in Table 1. The specific cycle life of each battery pair is shown in Table 1. As can be seen from Table 1, compared to the Zn∥Zn symmetric battery corresponding to ZP, the Zn∥Zn symmetric battery corresponding to ZP@CuC2O4 exhibits a significantly longer cycle life. Furthermore, the electrode containing 2wt% CuC2O4 shows the longest cycle life, significantly better than the unmodified zinc powder electrode and other addition ratios. This result indicates that the introduction of an appropriate amount of CuC2O4 can effectively improve the interfacial reaction behavior of the zinc powder anode and enhance deposition / stripping reversibility. However, too low a doping amount is insufficient to provide adequate interfacial regulation, while too high a doping amount may disrupt the continuity of conductivity / ion transport within the electrode due to the increased proportion of inactive components, thereby weakening cycle stability.

[0085] Figure 2 The Zn∥Zn symmetric cells corresponding to the ZP@CuC2O4 provided in Example 1 and the ZP provided in Comparative Example 1 were tested at 25°C and 1 mA cm⁻¹. -2 / 1mAh cm -2 Voltage-time cycle curve under the given conditions. From Figure 2 As can be seen, compared with the Zn∥Zn symmetric cell corresponding to ZP, the cycle life of the Zn∥Zn symmetric cell corresponding to ZP@CuC2O4 is significantly extended.

[0086] Figure 6 The Zn∥Zn symmetric cells corresponding to the ZP@CuC₂O₄ provided in Example 1 and the ZP provided in Comparative Example 1 were tested at 40°C and 0.5 mA cm⁻¹. -2 / 0.25mAh cm -2 Voltage-time cycle curves under the given conditions. As can be seen from the figure, compared to the Zn∥Zn symmetric cell corresponding to ZP, the Zn∥Zn symmetric cell corresponding to ZP@CuC2O4 exhibits a significantly longer cycle life and significantly improved high-temperature resistance.

[0087] Figure 7 The in-situ EIS comparison diagrams of the ZP@CuC2O4 electrode provided in Example 1 and the ZP electrode provided in Comparative Example 1, corresponding to Zn∥Zn symmetric cells, show the differences in the dynamic evolution of the two interfaces. The unmodified ZP electrode exhibits significant impedance distribution fluctuations and local enhancements during cycling, reflecting the continuous instability of the interface state during deposition / stripping. In contrast, the impedance evolution of the ZP@CuC2O4 electrode is significantly smoother, with the overall response remaining within a narrow range, indicating that its interface reaction process is effectively regulated. This result, from a dynamic perspective, shows that CuC2O4 modification not only changes the initial interface state but, more importantly, stabilizes the interface evolution path during cycling.

[0088] Figure 8The morphology and elemental distribution of ZP@CuC2O4 and ZP corresponding to ZP in Example 1 and Comparative Example 1 before cycling are shown in the figure. Figure 9 The Zn∥Zn symmetric cells corresponding to ZP@CuC2O4 provided in Example 1 and ZP provided in Comparative Example 1 were measured at 1 mA cm⁻¹. -2 / 1mAh cm -2 The morphology and elemental distribution of ZP@CuC2O4 and ZP are shown in the following figures after 100 cycles under the given conditions. Figure 8 and Figure 9 It can be seen that a clear Cu element signal is present in the prepared ZP@CuC2O4 electrode, indicating that the CuC2O4 modification component has been successfully introduced into the electrode system. Furthermore, at 1 mA cm⁻¹... -2 / 1mAh cm -2 SEM images after 100 cycles under current density conditions show that the surface of the unmodified zinc powder exhibits obvious rough accumulation and localized protrusions. Figure 9 a), the corresponding elemental EDS distribution diagram shows that the unmodified ZP electrode does not contain copper ( Figure 9 b、 Figure 9 c. Figure 9 d). The SEM images after cycling with the modified electrode show a more uniform and denser deposition layer. Figure 9 e). EDS distribution map of corresponding elements ( Figure 9 f、 Figure 9 g、 Figure 9 h) indicates that Cu, O and Zn are more uniformly distributed on the surface of the modified electrode, suggesting that interface regulation does not fail rapidly with cycling, but continues to affect the formation and expansion of the surface reaction area during the deposition process.

[0089] Figure 10 Tafel diagrams of Zn∥Zn symmetric cells corresponding to ZP@CuC2O4 provided in Example 1 and ZP provided in Comparative Example 1 are shown. As can be seen from the figure, the ZP@CuC2O4 electrode has a lower corrosion current and a more positive corrosion potential, clearly showing enhanced corrosion resistance.

[0090] Application Example 2

[0091] Preparation of Zn∥Cu half-cell:

[0092] The negative electrodes prepared in each embodiment and comparative example were assembled with copper sheets to form Zn∥Cu half cells. Glass fiber membranes and an appropriate amount of aqueous electrolyte (2mol / L ZnSO4 aqueous solution) were used to assemble 2025 type button zinc ion half cells (i.e. Zn∥Cu half cells).

[0093] Performance testing:

[0094] Nucleation overpotential test: The assembled Zn∥Cu half-cell was subjected to constant current deposition test at room temperature, with an applied current density of 0.5 mA cm⁻¹. -2 During the test, the voltage curve initially showed a sharp voltage drop, which then gradually recovered to a relatively stable plateau. The difference between the lowest point of the voltage drop and the subsequent stable plateau is the nucleation overpotential.

[0095] Coulomb efficiency test: The assembled Zn∥Cu half-cell was subjected to two sets of constant current charge-discharge tests at room temperature. Specifically, the first set was conducted at 0.2 mA cm⁻¹. -2 The current density of zinc deposition to an areal capacity of 0.1 mAh cm⁻¹ -2 (i.e., 0.2mA cm) -2 / 0.1mAh cm -2 The second group used 1mA cm -2 The current density of zinc deposition to an areal capacity of 0.5 mAh cm⁻¹ -2 (i.e., 1mA cm) -2 / 0.5mAh cm -2 Record the coulombic efficiency for each cycle in each test group until the coulombic efficiency drops significantly or the battery fails, thereby obtaining the number of stable cycles under each condition and calculating the average coulombic efficiency for the corresponding stage.

[0096] The specific results are shown in Table 2.

[0097] Table 2 Performance test results of Zn∥Cu half-cell

[0098]

[0099] Combining the overpotential curves of the ZP@CuC2O4 provided in Example 1 and the ZP corresponding half-cells provided in Comparative Example 1 ( Figure 11 As can be seen, the nucleation potential of the half-cell corresponding to ZP@CuC2O4 is significantly lower than that of the half-cell corresponding to ZP. This indicates that in the ZP@CuC2O4 electrode, the reduction of the energy barrier promotes the uniform nucleation of zinc and stabilizes the deposition process, thereby improving the anode performance.

[0100] Application Example 3

[0101] Preparation of Zn∥V₂O₅ full cells:

[0102] (1) Preparation of positive electrode material: V2O5, conductive agent Super P and polyvinylidene fluoride were weighed in a mass ratio of 7:2:1, with a total weight of 0.6g; the mixture was then coated onto a 500-mesh stainless steel mesh to obtain a positive electrode active material (V2O5) loading of approximately 2.5mg / cm³. -2 Vanadium-based cathode materials.

[0103] (2) Preparation of full cell: The above-mentioned vanadium-based positive electrode material is used as the positive electrode, ZP@CuC2O4 prepared in Example 1 or ZP prepared in Comparative Example 1 is used as the negative electrode, 2 mol / L ZnSO4 aqueous solution is used as the electrolyte, and glass fiber is used as the separator to construct a 225-type button Zn∥V2O5 full cell.

[0104] Performance testing:

[0105] 1. Constant current charge-discharge test at room temperature (25℃): The obtained Zn∥V₂O₅ full cell was charged and discharged at 15A g at room temperature. -1 Constant current charge-discharge tests were performed on the current density, and the number of cycles and the specific capacity retention value were recorded.

[0106] 2. Constant current charge-discharge test under high temperature (40℃): The obtained Zn∥V₂O₅ full cell was subjected to constant current charge-discharge test at 40℃ with a current of 7A g. -1 Constant current charge-discharge tests were performed on the current density, and the number of cycles and the specific capacity retention value were recorded.

[0107] Figure 12 Cycling performance graphs of ZP@CuC2O4 cells prepared in Example 1 and Zn∥V2O5 cells constructed with ZP prepared in Comparative Example 1 at 25°C; from Figure 12 It can be seen that compared with the faster capacity decay of the bare ZP system, the ZP@CuC2O4 full cell can still maintain considerable reversible capacity and relatively stable efficiency over a longer cycling range.

[0108] Figure 13 Cycling performance graphs of ZP@CuC2O4 full cells prepared in Example 1 and Zn∥V2O5 full cells constructed with ZP prepared in Comparative Example 1 at 40°C; from Figure 13 It can be seen that the Zn∥V₂O₅ full cell constructed by ZP@CuC₂O₄ performs well at 40℃ and 7A g. -1 After 533 cycles under the specified conditions, the specific capacity reached 157 mAh g. -1 However, the Zn∥V₂O₅ full cell constructed by ZP could not cycle normally.

[0109] Application Example 4

[0110] Fabrication of pouch cells:

[0111] Using ZP@CuC2O4 prepared in Example 1 as the negative electrode, the pouch battery includes a V2O5 positive electrode, a copper oxalate-modified zinc powder negative electrode, a glass fiber separator, a zinc salt electrolyte, positive and negative electrode tabs, and an aluminum-plastic film outer encapsulation layer. During assembly, the separator is placed between the positive and negative electrodes, and the positive and negative electrodes are connected to their corresponding tabs. After adding the electrolyte, the battery is encapsulated to obtain a pouch battery.

[0112] Performance testing:

[0113] 1. At room temperature (25℃), 7A g -1 Under the conditions described above, constant current charge-discharge tests were performed on the soft-pack batteries, and the number of cycles and the specific capacity retention value were recorded. Figure 14 For pouch cells at 7A g -1 Cycling performance at current density. The results show that the pouch cell can stably cycle for more than 1000 cycles.

[0114] 2. Use this pouch battery to power the electronic watch. The result is as follows: Figure 15 As shown, this pouch battery can power an electronic watch.

[0115] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A zinc powder anode based on phase change material modification, characterized in that, include: current collector; as well as, A negative electrode active material layer is disposed on at least one side surface of the current collector, and the negative electrode active material layer includes a negative electrode active material, which includes zinc powder and copper oxalate.

2. The negative electrode according to claim 1, characterized in that, The mass ratio of zinc powder to copper oxalate is 90~98:1~8.

3. The negative electrode according to claim 1, characterized in that, The zinc powder is in flake form, with an average particle size of 1~100μm and an aspect ratio of 40~80.

4. The negative electrode according to claim 3, characterized in that, The copper oxalate is dispersed on all or part of the outer surface of the flaky zinc powder particles; or, the copper oxalate is dispersed between the flaky zinc powder particles; or, some copper oxalate is dispersed on all or part of the outer surface of the flaky zinc powder particles, and some copper oxalate fills between the flaky zinc powder particles.

5. The negative electrode according to claim 1, characterized in that, The active material layer also includes a binder selected from one or more of polyvinylidene fluoride, polyacrylonitrile, polyimide, and perfluorosulfonic acid ionomers.

6. The negative electrode according to claim 1, characterized in that, The current collector is selected from at least one of copper foil, titanium foil, stainless steel foil, and stainless steel mesh.

7. A method for preparing a zinc powder anode based on phase change material modification as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Mix and grind zinc powder, copper oxalate and binder, then add organic solvent to form a slurry; S2. The slurry is coated onto at least one side of the current collector and then dried to obtain the zinc powder anode based on phase change material modification.

8. The preparation method according to claim 7, characterized in that, The organic solvent is selected from one or more of N-methylpyrrolidone, methyl vinyl ketone, dichloromethane, and ethanol; The drying temperature is 50~60℃.

9. An aqueous zinc-ion battery, characterized in that, This includes the zinc powder anode based on phase change material modification as described in any one of claims 1 to 6, or the zinc powder anode based on phase change material modification obtained by the preparation method according to any one of claims 7 to 8.

10. The aqueous zinc-ion battery according to claim 9, characterized in that, Includes positive electrode, negative electrode, electrolyte, and separator; The negative electrode is the zinc powder negative electrode based on phase change material modification according to any one of claims 1 to 6 or the zinc powder negative electrode based on phase change material modification obtained by the preparation method according to any one of claims 7 to 8; The positive electrode includes a positive electrode active material, which includes at least one of vanadium-based materials, manganese-based materials, and Prussian blue positive electrode materials. The electrolyte is an aqueous solution of zinc salt; The diaphragm is made of glass fiber.

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