Aqueous zinc ion battery electrolyte containing functional additive as well as preparation method and application of aqueous zinc ion battery electrolyte

Abstract

The invention relates to the field of aqueous zinc ion batteries, and particularly provides an aqueous zinc ion battery electrolyte containing a functional additive as well as a preparation method and application of the aqueous zinc ion battery electrolyte. Branched chain type polyethyleneimine with the molecular weight of 600 is added into the electrolyte, molecules of the branched chain type polyethyleneimine are rich in high-density amino groups and have high nucleophilicity, stable Zn-N coordinate bonds can be formed by the branched chain type polyethyleneimine and divalent zinc ions on the surface of a zinc negative electrode, multi-site strong adsorption anchoring is achieved, and zinc ion deposition kinetics are accurately regulated and controlled; zinc ions are induced to uniformly nucleate and compactly grow at adsorption sites, so that dendritic crystal generation is inhibited from the source; meanwhile, amino is a weakly alkaline group, the local pH environment of the surface of the zinc negative electrode can be adjusted in a targeted mode through protonation reaction, the hydrogen evolution reaction triggering condition is remarkably weakened, a three-dimensional protection layer can be constructed on the surface of the electrode through a branched chain structure, active water molecules in an electrolyte are isolated through the steric hindrance effect, direct contact between the zinc electrode and water is reduced, and the hydrogen evolution reaction efficiency is improved. And side reactions such as corrosion are synchronously inhibited.

Description

Technical Field

[0001] This invention relates to the field of aqueous zinc-ion battery technology, and particularly to an aqueous zinc-ion battery electrolyte containing functional additives, its preparation method, and its application. Background Technology

[0002] Secondary batteries are an important type of chemical energy storage device. Lithium-ion batteries, as a representative of secondary batteries, have been widely used in various fields of production and daily life. However, the development of lithium-ion batteries has been limited by their high manufacturing cost and safety issues caused by the flammability of organic electrolytes. In contrast, aqueous batteries are attracting increasing attention due to the inherent safety and environmental friendliness of their electrolytes, as well as their economic advantages. With the development of smart electronic devices, electric vehicles, and other fields, the requirements for energy density, fast charge / discharge performance, and safety performance of energy storage devices are becoming increasingly stringent. Among the many types of aqueous batteries, zinc-ion batteries are one of the most promising candidate materials.

[0003] Aqueous zinc-ion batteries (AZIBs), as an emerging energy storage technology, are considered an ideal candidate for large-scale energy storage due to their inherent safety, low cost, environmental friendliness, and high theoretical capacity. Their electrolyte, mainly composed of zinc salts (such as zinc sulfate and zinc trifluoromethanesulfonate) and water, is the core component determining the battery's overall performance. Currently, research and development surrounding the electrolyte has become a key focus in driving this technology from the laboratory to industrial application.

[0004] In recent years, the field of aqueous zinc-ion batteries has developed rapidly, with significant research efforts invested by the global academic and industrial communities. Its current development exhibits two main characteristics: Firstly, fundamental research is continuously deepening, leading to a more profound understanding of new cathode materials, electrolyte optimization, and interface mechanisms. Secondly, while industrialization has begun, large-scale commercialization has not yet been achieved, with the main obstacle being the zinc anode interface problems caused by aqueous electrolytes. Specifically, this manifests as: uncontrollable side reactions, centered on the electrochemical decomposition of water. On the zinc anode surface, the hydrogen evolution reaction (HER) continuously consumes electrolyte and generates gas, leading to increased internal pressure, decreased efficiency, and damage to the electrode structure. Simultaneously, the accompanying local pH increase induces the formation of non-conductive inert byproducts (such as basic zinc sulfate, ZSH) on the Zn surface, severely hindering ion transport and increasing interfacial impedance. Uncontrolled growth of zinc dendrites: Due to the uneven deposition of zinc ions on the electrode surface, sharp dendrites easily form. These dendrites can pierce the separator, causing internal short circuits in the battery, posing serious safety hazards, and leading to irreversible loss of active materials, significantly shortening the battery's cycle life. Poor interface stability: The aforementioned side reactions and dendrite problems together result in extremely unstable zinc anode / electrolyte interfaces, creating a vicious cycle. Conventional electrolyte additives or modification strategies often only address single problems (such as simply inhibiting dendrites or adjusting pH), making it difficult to achieve synergistic and long-lasting global protection.

[0005] Based on this, the present invention develops a functional additive that combines local pH adjustment capability, high-efficiency interfacial adsorption performance, and three-dimensional protection function. Summary of the Invention

[0006] This invention provides an aqueous zinc-ion battery electrolyte containing functional additives, its preparation method, and its application, with the aim of solving the aforementioned problems existing in the background art.

[0007] To achieve the above objectives, one aspect of the present invention provides an aqueous zinc-ion battery electrolyte containing a functional additive, wherein the functional additive is polyethyleneimine;

[0008] The electrolyte also includes soluble zinc salt and deionized water.

[0009] Preferably, the polyethyleneimine has the following molecular structure of Formula I:

[0010] ,

[0011] The molecular weight is 600.

[0012] Preferably, the concentration of the functional additive is 0.5~5 g / L. More preferably, the concentration of the functional additive is 1 g / L.

[0013] Preferably, the soluble zinc salt includes at least one of zinc sulfate, zinc chloride, zinc nitrate, and zinc trifluoromethanesulfonate, with a concentration of 0.5~4 mol / L.

[0014] Preferably, the concentration of the soluble zinc salt, zinc sulfate, is 1-3 mol / L. More preferably, the concentration of the soluble zinc salt, zinc sulfate, is 2 mol / L.

[0015] An embodiment of the present invention also provides a method for preparing an aqueous zinc-ion battery electrolyte containing functional additives, wherein soluble zinc salt and polyethyleneimine are added to deionized water and stirred thoroughly until completely dissolved to obtain the electrolyte.

[0016] Another aspect of the present invention provides a rechargeable aqueous zinc-ion battery, comprising the above-described aqueous zinc-ion battery electrolyte containing functional additives.

[0017] Preferably, the rechargeable aqueous zinc-ion battery is a symmetrical battery consisting of zinc foil as the positive and negative electrodes, glass fiber as the separator, and the electrolyte.

[0018] Preferably, the rechargeable aqueous zinc-ion battery is a half-cell consisting of stainless steel foil as the positive electrode, zinc foil as the negative electrode, glass fiber as the separator, and the electrolyte.

[0019] Preferably, the rechargeable aqueous zinc-ion battery is a complete battery consisting of zinc foil as the negative electrode, vanadium-based compound as the positive electrode, glass fiber as the separator, and the electrolyte.

[0020] More preferably, the vanadium-based compound ammonium vanadate (NH4V4O) 10 ).

[0021] The above-described solution of the present invention has the following beneficial effects:

[0022] (1) This invention introduces a functional additive with local pH adjustment capability, high-efficiency interfacial adsorption performance and three-dimensional protection function—branched polyethyleneimine (PEI) with a molecular weight of 600, which becomes a key technical means to break through the bottleneck of side reactions of zinc anode and promote the industrialization of aqueous zinc-ion batteries. Its molecules are rich in high-density amino groups (-NH2, -NH-), which have weak alkalinity and can precisely adjust the local pH of the anode surface through protonation reaction to weaken the triggering conditions of hydrogen evolution reaction. It can also form stable coordination bonds with divalent zinc ions to achieve strong adsorption and anchoring at multiple sites and guide the uniform nucleation and deposition of zinc ions. At the same time, the branched structure can construct a three-dimensional protective layer, which isolates active water molecules from contact with the electrode through the steric hindrance effect, and simultaneously achieves the triple goals of side reaction suppression, dendrite regulation and interfacial protection.

[0023] (2) When the electrolyte of the present invention is applied to a rechargeable aqueous zinc-ion battery, the electrochemical performance of the battery is significantly optimized, and the performance such as coulombic efficiency and long-cycle stability is greatly improved, effectively solving the pain points of short cycle life and low energy utilization efficiency of traditional aqueous zinc-ion batteries.

[0024] (3) The functional additive used in this invention has low toxicity and eco-friendliness, and its environmental compatibility is significant. At the same time, the additive is a general chemical raw material that has been mass-produced on a large scale. The market supply chain is mature and stable, and the raw materials are easy to obtain, which has an outstanding low-cost advantage. The amount of the additive added to the electrolyte is only 1g / L, which is a very small amount. Moreover, it does not require complicated pretreatment, which makes the electrolyte preparation process simple and easy to operate. It does not rely on special equipment, is easy to integrate with existing production processes, and is fully adapted to the needs of large-scale industrial production and market promotion and application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in 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.

[0026] Figure 1 The Zn||Zn symmetric cells using the electrolytes of Examples 1, 2, 3, and Comparative Example 1 of this invention are tested at 1 mA·cm⁻¹. -2 and 1mAh·cm -2 Cyclic performance diagram under the given conditions;

[0027] Figure 2 These are XRD patterns of zinc foils from Embodiment 1 and Comparative Example 1 after being immersed in the electrolyte for 14 days, and Comparative Example 2 (unimmersed zinc foil).

[0028] Figure 3 The LSV curves of stainless steel ||Zn half-cells assembled with electrolytes of Example 1 and Comparative Example 1 of the present invention are shown in the graphs.

[0029] Figure 4 The Zn||Zn symmetric cells with electrolytes from Embodiment 1 and Comparative Example 1 of the present invention are used at 1 mA·cm⁻¹ -2 and 1mAh·cm -2 SEM images under the condition of 20 cycles;

[0030] Figure 5 The Zn||Zn symmetric cells with electrolytes from Embodiment 1 and Comparative Example 1 of the present invention are used at 1 mA·cm⁻¹ -2 ~10mA·cm -2Rate performance graph within the current density range;

[0031] Figure 6 The Cu||Zn half-cells of the electrolytes in Examples 1 and 1 of the present invention are shown at 1 mA·cm⁻¹. -2 and 0.5mAh·cm -2 Cyclic coulomb efficiency diagram under the given conditions;

[0032] Figure 7 The electrolytes of Examples 1 and Comparative Example 1 of this invention contain NH4V4O. 10 ||Zn full cell at 2A·g -1 Long-cycle performance at current density;

[0033] Figure 8 The electrolytes of Examples 1 and Comparative Example 1 of this invention contain NH4V4O. 10 ||Capacity retention rate of Zn full cells after 48 hours of rest. Detailed Implementation

[0034] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0035] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0037] This invention addresses existing problems by providing an aqueous zinc-ion battery electrolyte containing functional additives, its preparation method, and its application.

[0038] Example 1

[0039] In this embodiment, the aqueous zinc-ion battery electrolyte consists of 2 mol / L zinc sulfate and 1 g / L polyethyleneimine.

[0040] The preparation method of the aqueous zinc-ion battery electrolyte in this embodiment includes the following steps:

[0041] Step (1): Accurately weigh 57.51g of zinc sulfate heptahydrate solid and 0.1g of polyethyleneimine into a beaker, add 70mL of deionized water and a stir bar, and stir thoroughly on a magnetic stirrer until completely dissolved, which takes 30~60min.

[0042] Step (2): Transfer the solution treated in step (1) completely to a 100 mL volumetric flask, add deionized water to make up to 100 mL, shake well to obtain the aqueous zinc-ion battery electrolyte.

[0043] Example 2

[0044] Compared with Example 1, the difference is that the amount of polyethyleneimine added is 0.05g, and the resulting electrolyte is 2mol / L zinc sulfate and 0.5g / L polyethyleneimine.

[0045] Example 3

[0046] Compared with Example 1, the difference is that the amount of polyethyleneimine added is 0.5g, and the resulting electrolyte is 2mol / L zinc sulfate and 5g / L polyethyleneimine.

[0047] Comparative Example 1

[0048] The difference from Example 1 is that polyethyleneimine is not added.

[0049] Comparative Example 2

[0050] Pure commercial zinc foil

[0051] The electrolytes from the above embodiments and comparative examples were used to assemble the following batteries for performance testing.

[0052] (1) Zn||Zn symmetric cell:

[0053] The positive and negative electrodes of the Zn||Zn symmetric battery are both made of commercial zinc foil with a diameter of 12 mm and a thickness of 100 micrometers, and a glass fiber separator is used between the positive and negative electrodes. Assembly is performed using a CR2025 battery case, with the following steps: first, the negative electrode case is installed, followed by the negative electrode spring and gasket, then the negative electrode sheet, then the glass fiber separator, followed by the injection of approximately 100 microliters of electrolyte, then the positive electrode sheet, and finally the positive electrode case. The entire assembly process is completed in air, and pressure sealing is applied after assembly.

[0054] (2) Stainless steel || Zn half-cell:

[0055] The positive electrode of the stainless steel||Zn half-cell is made of commercial stainless steel foil with a diameter of 12 mm and a thickness of 30 micrometers, and the negative electrode is made of commercial zinc foil with a diameter of 12 mm and a thickness of 100 micrometers. Glass fiber is used as a separator between the positive and negative electrodes. The battery assembly method is the same as (1).

[0056] (3) Cu||Zn half-cell:

[0057] The positive electrode of the Cu||Zn half-cell is made of commercial copper foil with a diameter of 12 mm and a thickness of 30 micrometers, and the negative electrode is made of commercial zinc foil with a diameter of 12 mm and a thickness of 30 micrometers. Glass fiber is used as a separator between the positive and negative electrodes. The battery assembly method is the same as (1).

[0058] (4)NH4V4O 10 ||Zn full battery:

[0059] NH4V4O 10 Preparation: 1.17 g of ammonium metavanadate was transferred to a beaker containing 50 mL of deionized water at 80 °C. The beaker was covered with perforated plastic wrap and stirred on a magnetic stirrer until the solution turned a clear, pale yellow color. Then, 1.891 g of H₂C₂O₄·H₂O was added to the solution, and stirring continued until a deep blue color was achieved. The deep blue liquid was transferred to an 80 mL reaction vessel and subjected to a hydrothermal reaction at 140 °C for 48 hours. After the reaction was complete, the solution was filtered, washed, and vacuum dried to obtain the active NH₄V₄O₂. 10 Positive electrode material.

[0060] NH4V4O 10 Preparation of the positive electrode: First, NH4V4O 10 The positive electrode material, Super-P acetylene black, and PVDF were mixed in NMP solvent at a mass ratio of 7:2:1 to obtain a uniform slurry. The resulting slurry was coated onto a 12 mm diameter stainless steel mesh and dried in a vacuum drying oven at 80 °C for 12 hours. The mass loading of the positive electrode active material was approximately 3 mg·cm³. -2 .

[0061] NH4V4O 10 The positive electrode of the Zn full cell uses the aforementioned NH4V4O. 10 The positive electrode and the negative electrode are made of commercial zinc foil with a diameter of 12 mm and a thickness of 100 micrometers. Glass fiber is used as a separator between the positive and negative electrodes. The battery assembly method is the same as (1).

[0062] 1. Cycle performance of Zn||Zn symmetric cells

[0063] The assembled Zn||Zn symmetric cell was subjected to constant current charge-discharge testing at 30°C with a current density of 1 mA·cm⁻¹. -2 Surface capacity is 1mAh·cm -2 .like Figure 1As shown, the zinc anode using Comparative Example 1 (pure zinc salt electrolyte) failed rapidly after 50 hours of cycling. This was due to the lack of effective interface control mechanisms in this system, leading to disordered dendrite growth on the zinc anode surface. Simultaneously, side reactions such as corrosion and hydrogen evolution accumulated, disrupting the stability of the anode interface and ultimately causing battery failure. Electrolytes containing different concentrations of polyethyleneimine (PEI) additives showed significant differences: Example 1 (PEI concentration 1 g / L): The battery cycle life exceeded 2000 hours, and the charge-discharge voltage curve remained stable. This is because the 1 g / L PEI concentration allows the high-density amino groups in its molecules to fully anchor the zinc anode interface, forming a complete three-dimensional protective layer. This layer guides the uniform nucleation of zinc ions through coordination bonds, inhibits dendrite growth, and uses the weakly basic amino groups to regulate the local pH to block side reactions. It also does not increase electrolyte viscosity, ensuring efficient zinc ion transport and ultimately stabilizing the anode interface state. Example 2 (PEI concentration 0.5 g / L): The battery failed after approximately 900 hours of cycling. This is because the PEI concentration is too low, resulting in insufficient molecular quantity, making it impossible to form a continuous adsorption-protective layer on the zinc anode surface. Some areas lack the anchoring and pH regulation effects of amino groups, leading to dendrite growth and corrosion side reactions, resulting in a gradual deterioration of interface stability. Example 3 (PEI concentration 5 g / L): During cycling, the voltage gradually showed significant drift. Although the lifespan was longer than in Example 2, it was far shorter than in Example 1. This is because excessively high PEI concentrations increase electrolyte viscosity, reducing the zinc ion transport rate. Simultaneously, excessive PEI molecules tend to aggregate on the electrode surface, interfering with the uniform deposition of zinc ions. Aggregated areas easily become active sites for dendrite growth, thus affecting the long-term stability of the anode interface. This result demonstrates that 1 g / L is the optimal concentration of polyethyleneimine as an electrolyte additive for aqueous zinc-ion batteries. At this concentration, PEI can simultaneously achieve a synergistic effect of "interface protection + ion transport + deposition regulation," maximizing the battery's cycle stability.

[0064] 2. XRD test

[0065] Two zinc foils, each 12 mm in diameter, were immersed in the electrolytes of Example 1 and Comparative Example 1, respectively, for 14 days. After removal, they were gently rinsed with distilled water and dried under vacuum. They were then dried together with pure commercial zinc foil from Comparative Example 2, and XRD (X-ray diffraction) tests were performed. Figure 2 As shown, the XRD patterns of zinc foil samples under different treatment methods (the pentagram marks correspond to the characteristic peaks of the byproduct basic zinc sulfate hexahydrate, and the triangle marks correspond to the characteristic peaks of zinc (Zn): The pattern of Comparative Example 1 (pure zinc salt electrolyte) shows obvious characteristic peaks of byproducts (pentagrams), indicating that a large amount of zinc corrosion products are generated on its surface.

[0066] In the spectra of Comparative Example 2 (pure commercial zinc foil) and Example 1 (electrolyte containing 1 g / L of branched polyethyleneimine with a molecular weight of 600), only the characteristic peak (triangle) of zinc (Zn) was observed, and no characteristic signals of any byproducts were observed. This result indicates that branched polyethyleneimine with a molecular weight of 600 can form a highly efficient protective layer on the zinc anode surface. The high-density amino groups (-NH2, -NH-) in its molecule not only form stable Zn-N coordination bonds with divalent zinc ions through strong nucleophilicity, achieving multi-site anchoring to tightly cover the zinc interface, but also, through weak alkalinity, regulate the local pH of the anode surface through protonation reactions, weakening the triggering conditions for corrosion side reactions. At the same time, the three-dimensional protective layer constructed by the branched structure can effectively isolate the active water molecules in the electrolyte from direct contact with the zinc anode. The above multiple effects synergistically block the corrosion path of the zinc anode and significantly inhibit the formation of corrosion products such as basic zinc sulfate hexahydrate.

[0067] 3. LSV Test

[0068] Stainless steel ||Zn half-cells assembled using electrolytes from Example 1 (containing 1 g / L of branched polyethyleneimine with a molecular weight of 600) and Comparative Example 1 (pure zinc salt electrolyte) were subjected to linear sweep voltammetry (LSV) tests on a Shanghai Chenhua CHI660E electrochemical workstation to characterize the hydrogen evolution reaction behavior of the zinc anode.

[0069] like Figure 3 As shown, the hydrogen evolution overpotential of the zinc metal anode in the electrolyte of Example 1 is significantly greater than that in the electrolyte of Comparative Example 1 (manifested as a more negative voltage corresponding to the sudden drop in hydrogen evolution current in the curve of Example 1). The core mechanism of this difference lies in the fact that the weakly basic amino groups (-NH2, -NH-) abundant in the branched polyethyleneimine molecule with a molecular weight of 600 can precisely regulate the local pH environment on the surface of the zinc anode through protonation reaction. At the same time, its multi-site adsorption and anchoring effect and three-dimensional protective layer can reduce the contact probability between active water molecules and the anode. The dual effect jointly enhances the kinetic barrier of the hydrogen evolution reaction, thereby delaying the initiation process of the hydrogen evolution reaction, verifying the excellent suppression effect of this concentration of polyethyleneimine on the hydrogen evolution side reaction in aqueous zinc-ion batteries.

[0070] 4. SEM characterization

[0071] The Zn||Zn symmetric cells of Example 1 and Comparative Example 1, at 1 mA·cm -2 Current density, 1 mAh·cm -2 After 20 cycles under the deposition capacity conditions, the zinc anode sheet was removed: it was gently rinsed with distilled water to remove residual electrolyte, and then dried in a vacuum environment. The surface of the dried zinc foil was characterized by scanning electron microscopy (SEM), and the results are as follows: Figure 4As shown: The zinc foil surface corresponding to Example 1 exhibits a uniform and dense fine-grained morphology with high overall flatness, uniform particle size (mainly submicron level), no obvious dendrite protrusions, cracks or loose deposits, and a regular deposition layer structure; The zinc foil surface corresponding to Comparative Example 1 exhibits a rough and disordered characteristic, with not only large-sized agglomerated particles, but also obvious cracks and loose pores, a chaotic surface structure, and irregular protrusions visible locally (which are disordered zinc dendrites or corrosion byproducts). The core mechanism of this difference lies in the interfacial regulation of branched polyethyleneimine with a molecular weight of 600: the high-density amino groups (-NH2, -NH-) in its molecule can form stable Zn-N coordination bonds with divalent zinc ions, achieving strong adsorption and anchoring at multiple sites, precisely regulating the deposition kinetics of zinc ions, and inducing zinc to nucleate uniformly and grow densely at the adsorption sites; at the same time, its branched structure can build a three-dimensional protective layer on the negative electrode surface, restricting the disordered aggregation of zinc ions and promoting the formation of fine-particle, uniform-sized deposition layers. Therefore, the zinc foil of Example 1 still maintains a regular and dense surface after cycling; while Comparative Example 1, due to the lack of effective interfacial regulation, has a disordered zinc ion deposition process and prominent corrosion side reactions, ultimately forming a rough and defective surface structure.

[0072] 5. Electrochemical performance

[0073] Evaluation of Zn||Zn symmetric cells, Cu||Zn half-cells, and NH4V4O on the Neware battery testing system (CT-4008-5V10mA-164) 10 Electrochemical performance of Zn full cells.

[0074] (1) Symmetrical rate performance of Zn||Zn

[0075] The assembled Zn||Zn symmetric cell was subjected to rate performance testing at 30°C, with the current density set to 1 mA·cm⁻¹. -2 ~10mA·cm -2 .like Figure 5 As shown, the battery using the electrolyte of Example 1 exhibits stronger rate capability, and its voltage curve remains regular and exhibits minimal fluctuations across various current density gradients, even at 10 mA·cm⁻¹. -2 At high current densities, the voltage response remains stable and controllable. However, the voltage curve of the battery using zinc sulfate electrolyte shows that when the current density increases to 2 mA·cm⁻¹, the voltage response remains stable and controllable. -2 A significant voltage drop was already observed, and the voltage fluctuations continued to intensify during subsequent gradient switching, eventually leading to a short circuit. This test result further confirms that polyethyleneimine not only improves the long-cycle stability of the battery but also optimizes the kinetic behavior of the zinc anode, significantly enhancing the rate performance of aqueous zinc-ion batteries.

[0076] (2) Cu||Zn half-cell

[0077] At 1mA·cm -2 and 0.5mAh·cm -2 Under these conditions, the assembled Cu||Zn half-cell was subjected to constant current charge-discharge testing at 30℃, with the first step being the discharge process. For example... Figure 6 As shown, the Cu||Zn half-cell using Example 1 (electrolyte containing 1 g / L of branched polyethyleneimine with a molecular weight of 600) had an average coulombic efficiency (CE) of 99.1% over 600 cycles, with no significant fluctuations throughout. This excellent result stems from the interfacial regulation effect of branched polyethyleneimine with a molecular weight of 600: the high-density amino groups in its molecule can form stable Zn-N coordination bonds with divalent zinc ions, achieving strong adsorption and anchoring at multiple sites, guiding zinc ions to uniformly nucleate and densely deposit, effectively inhibiting dendrite growth; at the same time, the weak alkalinity of the amino groups regulates the local pH, and the three-dimensional protective layer constructed by the branched structure isolates active water molecules, significantly reducing the occurrence of side reactions such as hydrogen evolution and corrosion, ensuring the high reversibility of the zinc deposition / dissolution process, thus maintaining long-term stable coulombic efficiency; while the half-cell using Comparative Example 1 (pure zinc salt electrolyte) only showed drastic fluctuations in CE after 50 cycles, because the pure zinc sulfate electrolyte lacks effective interfacial regulation methods, and disordered dendrites are easily generated on the zinc anode surface, while the continuous accumulation of side reactions destroys the reversibility of the deposition layer, ultimately leading to rapid deterioration of coulombic efficiency and battery failure.

[0078] (3)NH4V4O 10 ||Zn full-cell cycle performance

[0079] The assembled NH4V4O 10 ||Zn full cells are placed in an environment of 30℃, within a voltage range of 0.4V to 1.4V, at a rate of 2A·g -1 Charge-discharge cycle tests were conducted at the current density, and the results are as follows: Figure 7 As shown: NH4V4O was used in Example 1 (electrolyte containing 1 g / L branched polyethyleneimine with a molecular weight of 600). 10 ||Zn full cell at 2A·g -1Under certain conditions, it can still maintain a high reversible specific capacity after 1000 cycles, with a capacity retention rate of 90.9%, and the coulombic efficiency remains stable at a level close to 100% throughout the process. This result is due to the efficient regulation effect of 600-molecular-weight branched polyethyleneimine on the zinc anode interface: the high-density amino groups in its molecule can form stable Zn-N coordination bonds with divalent zinc ions, achieving strong adsorption and anchoring at multiple sites, guiding zinc ions to uniformly nucleate and densely deposit, and inhibiting dendrite growth from the source; at the same time, the weak alkalinity of the amino groups can precisely regulate the local pH of the anode surface, weakening the triggering conditions of hydrogen evolution reaction. Combined with the three-dimensional protective layer constructed by the branched structure, it effectively isolates active water molecules and reduces the generation of corrosion byproducts. The zinc anode can still maintain a stable interface state after long-term cycling, which not only avoids the ineffective consumption of zinc active materials, but also prevents byproducts from migrating to the positive electrode interface.

[0080] The full cell using Comparative Example 1 (pure zinc salt electrolyte) had a capacity retention of only 65.8% after 1000 cycles. This is because pure zinc sulfate electrolyte lacks effective interface control methods, and disordered dendrite growth and corrosion side reactions easily occur on the zinc anode surface. On the one hand, the zinc active material is excessively consumed, and on the other hand, the generated byproducts migrate to the positive electrode interface with the electrolyte, blocking the ion transport channels of the positive electrode and destroying the active structure of the positive electrode. This leads to a continuous deterioration in the electrochemical synergy between the positive and negative electrodes, and ultimately the capacity and coulombic efficiency of the full cell deteriorate simultaneously.

[0081] (4) NH4V4O 10 ||Zn full cell self-discharge performance

[0082] The assembled NH4V4O 10 After the Zn full battery completed its first charge and discharge cycle at 30°C, it was left to stand for 48 hours (simulating a self-discharge process) before undergoing a discharge test to characterize the battery's self-discharge capacity retention. The results are as follows: Figure 8As shown: Comparative Example 1 (pure zinc salt electrolyte): After standing for 48 hours, the coulombic efficiency was only 84.01%, indicating severe self-discharge. This is because the zinc anode interface in the pure zinc sulfate electrolyte lacks effective protection, and side reactions such as dendrite growth and hydrogen evolution corrosion continue to occur during the standing period. Simultaneously, anode byproducts easily migrate to the cathode and undergo additional reactions, leading to increased loss of active materials at both electrodes and significant capacity loss. Example 1 (electrolyte containing 1 g / L of 600 molecular weight branched polyethyleneimine): After standing for 48 hours, the coulombic efficiency reached 92.06%, and the degree of self-discharge was significantly reduced. This result stems from the stable adsorption-protection system constructed by polyethyleneimine on the zinc anode surface: its high-density amino groups have a multi-site anchoring effect, which can still inhibit the spontaneous corrosion and disordered dendrite growth of the zinc anode during the static stage, reducing the ineffective consumption of zinc active materials; at the same time, the three-dimensional protective layer formed by the branched structure can block the migration of anode byproducts to the cathode, reduce the probability of cross-reactions between the cathode and anode, thereby effectively suppressing the self-discharge process and improving the battery capacity retention rate.

[0083] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An aqueous zinc-ion battery electrolyte containing functional additives, characterized in that, The functional additive is polyethyleneimine; The electrolyte also includes soluble zinc salt and deionized water.

2. The aqueous zinc-ion battery electrolyte containing functional additives according to claim 1, characterized in that, The polyethyleneimine has the following molecular structure of formula I: Its molecular weight is 600.

3. The aqueous zinc-ion battery electrolyte containing functional additives according to claim 1, wherein the concentration of the functional additives is 0.5~5g / L.

4. The aqueous zinc-ion battery electrolyte containing functional additives according to claim 1, wherein the soluble zinc salt comprises at least one of zinc sulfate, zinc chloride, zinc nitrate and zinc trifluoromethanesulfonate, with a concentration of 0.5~4 mol / L.

5. The aqueous zinc-ion battery electrolyte containing functional additives according to claim 4, wherein the soluble zinc salt is zinc sulfate with a concentration of 1~3 mol / L.

6. A method for preparing an aqueous zinc-ion battery electrolyte containing functional additives as described in any one of claims 1 to 5, characterized in that, Soluble zinc salt and polyethyleneimine are added to deionized water and stirred thoroughly until completely dissolved to obtain the electrolyte.

7. A rechargeable aqueous zinc-ion battery, characterized in that, This includes an aqueous zinc-ion battery electrolyte containing functional additives as described in claims 1 to 5.

8. A rechargeable aqueous zinc-ion battery according to claim 7, characterized in that, The rechargeable aqueous zinc-ion battery is a symmetrical battery composed of zinc foil as the positive and negative electrodes, glass fiber as the separator, and the electrolyte.

9. The rechargeable battery according to claim 7, characterized in that, The rechargeable aqueous zinc-ion battery is a half-cell consisting of stainless steel foil as the positive electrode, zinc foil as the negative electrode, glass fiber as the separator, and the electrolyte.

10. The rechargeable battery according to claim 7, characterized in that, The rechargeable aqueous zinc-ion battery is a complete battery consisting of zinc foil as the negative electrode, vanadium-based compound as the positive electrode, glass fiber as the separator, and the electrolyte.

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