Aqueous zinc ion battery based on TEMPO regulation and preparation method thereof

Abstract

The invention relates to the field of aqueous zinc battery materials. The invention provides an aqueous zinc ion battery based on TEMPO regulation and a preparation method thereof. The battery comprises a shell, an electrode assembly, a diaphragm and an electrolyte, the electrode assembly comprises a positive plate and a negative plate which are arranged at two ends in the shell, the diaphragm is arranged between the positive plate and the negative plate, the electrolyte is filled in the shell and infiltrates the surface of the electrode assembly and the diaphragm, and TEMPO is dissolved in the electrolyte. The preparation method comprises the following steps: S1, preparing an aqueous solution of Zn (CF3SO3) 2 as a basic electrolyte; s2, adding TEMPO into the basic electrolyte to form a composite electrolyte; s3, sequentially arranging the positive plate, the diaphragm and the negative plate in the shell; and S4, injecting the composite electrolyte into the shell, and sealing and packaging to obtain the aqueous zinc ion battery. On the basis of maintaining the overall structure of the battery system to be simple, dendritic crystal growth is inhibited, dead zinc is eliminated, the comprehensive performance of the battery is improved, and the battery is suitable for various application scenes.

Description

Technical Field

[0001] The present application relates to the field of aqueous zinc-ion battery materials, and more specifically, to an aqueous zinc-ion battery based on TEMPO regulation and a preparation method thereof. Background Art

[0002] Aqueous zinc-ion batteries (Zn-ion batteries) are widely considered a promising candidate for next-generation energy storage systems due to their safety, environmental friendliness, and low cost. Their basic structure typically consists of a metallic zinc anode, an aqueous electrolyte, and a suitable cathode material. Energy storage and release are achieved through the reversible deposition and stripping of zinc ions.

[0003] However, this type of battery generally faces the problem of zinc negative electrode dendrite growth and "dead zinc" accumulation in actual operation, which can easily cause battery short circuit, capacity attenuation and cycle performance degradation, seriously restricting its application reliability. In order to meet the above challenges, researchers have made some progress in recent years by constructing interface regulation mechanisms through electrolyte functionalization design. Among them, the introduction of trace interface regulation additives has become an effective strategy to improve the deposition behavior of zinc negative electrode - this type of additives can regulate the Zn 2+ Solvation structure, guiding the orientation of deposited crystal planes, or inducing the formation of a dense passivation film can improve interface stability at multiple scales. Additives with reversible redox behavior have attracted much attention because they can provide electron mediation and have been proven to alleviate the problems of dendrite formation and "dead zinc". However, existing redox additives still have key limitations: their redox potential is not compatible enough with zinc negative or positive electrode materials, and it is difficult to form a long-lasting and stable passivation layer. They are prone to induce side reactions, reduced cycle stability, or decomposition and deposition of the additives themselves, making it difficult to stably perform the interface regulation function.

[0004] Therefore, there is an urgent need to develop a new additive with a high redox potential matching the electrode material and an interface passivation function, so as to achieve long-term stable regulation of the zinc negative electrode interface and improve the cycle life and operational reliability of aqueous zinc-ion batteries. Summary of the Invention

[0005] The purpose of the present invention is to provide an aqueous zinc ion battery based on TEMPO regulation and a preparation method thereof, in order to address the deficiencies in the above-mentioned prior art, such as the insufficient potential matching of redox additives and the lack of interface passivation function.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: The present application provides an aqueous zinc-ion battery based on TEMPO regulation, comprising a shell, an electrode assembly, a diaphragm and an electrolyte. The electrode assembly comprises a positive electrode sheet and a negative electrode sheet arranged at both ends of the shell, the diaphragm is arranged between the positive electrode sheet and the negative electrode sheet, the electrolyte is filled in the shell, the electrolyte simultaneously infiltrates the surface of the electrode assembly and the diaphragm, and TEMPO is dissolved in the electrolyte.

[0007] The aqueous zinc-ion battery of this application introduces 2,2,6,6-tetramethylpiperidinyl oxide (TEMPO) as a redox additive in the electrolyte, establishing a composite control mechanism centered on interfacial charge regulation and deposition induction. TEMPO is an organic molecule with a stable free radical structure. Its redox intermediate state can stably exist at the electrode interface and participate in the electron regulation process. During battery discharge, zinc ions tend to preferentially form deposition nuclei in areas of high electric field intensity on the negative electrode surface, which can easily lead to uneven deposition and dendrite growth. After TEMPO molecules accumulate near the negative electrode interface, their oxidized state can dynamically accept electrons, alleviating the local electric field enhancement caused by interfacial charge accumulation. This promotes uniform zinc ion migration in multiple directions and nucleation, contributing to the formation of a fine-grained and evenly distributed deposition structure. During the continuous deposition process, TEMPO also cooperates with electrolyte anions and water decomposition products to induce the in situ formation of an interfacial product layer composed primarily of ZnF2 and ZnO at the negative electrode interface. This product layer exhibits excellent density and interfacial selectivity, effectively isolating the newly generated metallic zinc from direct contact with the electrolyte, thereby suppressing side reactions and stabilizing the electrode surface. During the battery charging phase, the reduced state of TEMPO molecules can participate in local electron transfer regulation near the interface, providing a recovery path for areas with incomplete deposition or electrical contact failure, helping to activate some failed metallic zinc, reducing the accumulation of "dead zinc" and improving material utilization efficiency. Through the above mechanism, TEMPO combines multiple functions such as zinc deposition morphology regulation, interface product layer induction, and reaction potential adaptation, enhancing the stability of the interface and the continuity of the reaction process, effectively improving the cycle performance and operational reliability of aqueous zinc-ion batteries.

[0008] Furthermore, the concentration of TEMPO in the electrolyte is 5-12 mmol / L. This concentration range ensures that TEMPO has sustained redox activity during the charge and discharge process, which is conducive to stabilizing the interface regulation effect.

[0009] Furthermore, the electrolyte solution uses Zn(CF3SO3)2 as the electrolyte salt, and the molar concentration ratio of TEMPO to Zn(CF3SO3)2 is 1:170-1:400. This ratio configuration can balance the effective transmission of zinc ions with the effective concentration of the additive, achieving good film-forming behavior and crystal suppression effects.

[0010] Furthermore, the positive electrode sheet is made of manganese dioxide material, the negative electrode sheet is made of metallic zinc, and the separator is made of glass fiber material.

[0011] Furthermore, the surface area of ​​the negative electrode sheet has an interface structure layer rich in ZnF2 and ZnO. This structure layer helps to isolate the direct contact between the electrolyte and the metallic zinc, inhibiting side reactions and enhancing interface stability.

[0012] Furthermore, the working density of aqueous zinc-ion batteries is 0.1-5 mA / cm 2 .

[0013] This application also proposes a method for preparing an aqueous zinc ion battery based on TEMPO regulation, which comprises the following steps: S1. Prepare an aqueous solution of Zn(CF3SO3)2 as the basic electrolyte; S2, adding TEMPO to the base electrolyte to form a composite electrolyte; S3, sequentially placing the positive electrode sheet, the separator, and the negative electrode sheet inside the housing; S4. Inject the composite electrolyte into the shell, and seal it to obtain an aqueous zinc ion battery.

[0014] Furthermore, in S2, TEMPO is pre-dissolved in ethanol or acetone as a solvent. This step helps reduce the local aggregation tendency of TEMPO in the aqueous phase and improves its dispersion uniformity in the electrolyte, thereby accelerating its participation in the regulation reaction at the electrode interface.

[0015] Furthermore, in S3, before the negative electrode sheet is placed inside the shell, the surface of the negative electrode sheet is wiped with anhydrous ethanol to remove oxides and impurities, thereby improving the surface cleanliness and wettability of the negative electrode sheet.

[0016] Furthermore, before S4 is sealed and packaged, the shell filled with the composite electrolyte is treated with ultraviolet light. This light process can stimulate the active state of some functional groups in the solution, accelerate the formation of TEMPO adsorption and coordination structures on the electrode surface, and strengthen its induction effect on the nucleation behavior of the zinc negative electrode from the initial stage.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: the aqueous zinc ion battery provided by the present application improves the stability and comprehensive performance of the battery while maintaining the simplicity of the overall structure of the system by introducing TEMPO as a redox additive in the electrolyte. TEMPO molecules have reversible electron transfer capabilities, participate in regulating the nucleation and deposition processes of zinc ions, effectively promote the dense and uniform deposition of metallic zinc, thereby inhibiting dendrite growth, reducing the risk of short circuits, and enhancing the stability of the interface structure. At the same time, its redox reaction mechanism helps to inhibit corrosion-inducing factors, construct a stable interface layer rich in ZnF2 / ZnO, reduce the self-corrosion rate of the zinc negative electrode and the probability of side reactions, and extend the cycle life of the battery. The composite electrolyte system constructed by TEMPO has both a wide electrochemical stability window and good polarization buffering capacity, supports higher operating voltages and fast charge and discharge processes, and exhibits excellent rate response and coulombic efficiency. Overall, the solution of the present invention achieves multi-faceted coordinated optimization of zinc negative electrode stability, electrolyte compatibility and energy output capacity without relying on structural complexity or high-cost modifications, thereby improving the battery's cycle life, rate response capability and operational safety. It is suitable for various application scenarios such as distributed energy storage, portable electronic devices, etc. that have high requirements for safety and life. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a TEMPO-regulated aqueous zinc ion battery provided by the present invention; Figure 2 This is a scanning electron microscope image of the negative electrode sheet of an aqueous zinc-ion full battery after 50 charge and discharge cycles; Figure 3 is the X-ray diffraction pattern of the zinc deposition layer after 50 cycles; Figure 4 This is the X-ray photoelectron spectroscopy test result of the negative electrode of the Zn||Zn symmetric battery after 100 hours of cycling; Figure 5 The graph shows the chronoamperometry test results of the Zn||Zn symmetrical battery; Figure 6 This is the cyclic voltammetry test result of Zn||Cu half-cell; Figure 7 This is the linear sweep voltammetry test result of Zn||Cu half-cell; Figure 8 This is the electrochemical impedance spectroscopy test result of Zn||Cu half-cell; Figure 9 This is the linear polarization test result diagram of the Zn||Zn symmetric battery; Figure 10 A schematic diagram of another aqueous zinc ion battery based on TEMPO regulation provided by the present invention; Figure 11 This is the result of cyclic voltammetry test of aqueous zinc ion full battery; Figure 12 This is the result of the rate performance test of aqueous zinc-ion full battery; Figure 13 This is a graph showing the long cycle performance test results of an aqueous zinc-ion full battery at a current density of 4A / g.

[0019] Icon: 1-shell; 2-diaphragm; 3-positive electrode; 4-negative electrode; 5-composite electrolyte. DETAILED DESCRIPTION

[0020] In order to make the implementation process of the present invention clearer, it will be described in detail below with reference to the accompanying drawings.

[0021] Example 1: The present invention provides an aqueous zinc ion battery based on TEMPO regulation, such as Figure 1 As shown, it includes a shell 1, an electrode assembly, a diaphragm 2 and an electrolyte. The electrode assembly includes a positive electrode sheet 3 and a negative electrode sheet 4 arranged at both ends inside the shell 1. The diaphragm 2 is arranged between the positive electrode sheet 3 and the negative electrode sheet 4. The electrolyte is filled in the shell 1. The electrolyte simultaneously infiltrates the surface of the electrode assembly and the diaphragm 2. TEMPO is dissolved in the electrolyte.

[0022] The battery case 1 is assembled from a positive electrode shell and a negative electrode shell, forming the upper and lower structures of the battery case 1, respectively. The positive electrode shell can be made of a polymer material with electrochemical stability and structural strength, such as polypropylene (PP) or polyvinylidene fluoride (PVDF), to provide mechanical support and mount the positive electrode sheet 3. The negative electrode shell can be made of epoxy resin-reinforced material, polycarbonate (PC), or a composite material with high gas barrier properties. It not only mounts the negative electrode sheet 4 and provides lower structural support, but also meets the sealing and stability requirements of the negative electrode interface. A sealed connection structure is provided between the positive and negative electrode shells, which can be connected by heat pressing, colloid sealing, or laser welding. A central cavity is formed in the shell 1 for accommodating the electrode assembly and injecting electrolyte. Internally, it can be equipped with retaining ribs or positioning grooves to maintain consistent positioning of the electrode assembly during assembly. This structure improves the package sealing and interface stability, reduces the impact of the external environment on the battery's internal reactions, and provides a closed environment for subsequent electrochemical reactions.

[0023] The electrode assembly consists of a positive electrode sheet 3 and a negative electrode sheet 4. The positive electrode sheet 3 uses manganese dioxide as its active material, while the negative electrode sheet 4 is a high-purity zinc sheet approximately 0.1 mm thick. The positive electrode sheet 3 is mounted inside the positive electrode casing, and the negative electrode sheet 4 is mounted inside the negative electrode casing, facing each other. The electrode assemblies are identical in size, matching the dimensions of the casing 1. The separator 2 is positioned between the positive electrode sheet 3 and the negative electrode sheet 4. Made of fiberglass and cut to size slightly larger than the electrode assembly, it ensures adequate isolation between the positive and negative electrodes 3 and 4. The separator 2 has a porous structure with a pore size range of 0.1-0.6 μm. This effectively blocks direct electron penetration between the positive and negative electrodes, preventing short circuits, while also ensuring smooth migration of zinc ions during charge and discharge. This pore size range balances isolation and ion conductivity, contributing to improved Coulombic efficiency and cycle stability of the battery. During assembly, the separator 2 is smoothly positioned on the surface of the positive electrode sheet 3 and then covers the negative electrode sheet 4, forming an electrochemical reaction unit. After the electrolyte is injected, it can evenly infiltrate the positive electrode sheet 3, the negative electrode sheet 4 and the separator 2 to form a complete ion transmission channel.

[0024] In this embodiment, the positive electrode sheet 3 is obtained by coating the active material on the surface of the titanium foil and drying and shaping it. Specifically, manganese dioxide powder, conductive carbon black powder and polyvinylidene fluoride binder powder are weighed, mixed in a mass ratio of 8:1:1, and placed in a container with a lid. An appropriate amount of N-methylpyrrolidone is added as a solvent, and a mechanical stirrer is used to continuously stir for more than 30 minutes at room temperature until a uniform, fine slurry with good fluidity is formed. The prepared slurry is evenly coated on the surface of a metal titanium foil with a thickness of 60 μm, and the slurry thickness is controlled by blade coating. The titanium foil is used as a current collector here, and has good conductivity, interface stability and mechanical strength. After coating, the titanium foil is allowed to stand for 5 minutes to facilitate the initial shaping of the surface and reduce the risk of edge warping or cracking. It is then placed in a vacuum drying oven and dried at 120°C for 12 hours to fully remove the solvent and promote film densification. After drying, it is cut into specifications that match the size of the shell 1, that is, the positive electrode sheet 3 is produced and used in the subsequent assembly process. It has high structural stability and electronic conductivity performance and is suitable for the positive electrode construction of aqueous zinc ion batteries.

[0025] Furthermore, the electrolyte uses zinc trifluoromethanesulfonate (Zn(CF3SO3)2) as the electrolyte salt, dissolved in deionized water to form a base electrolyte, which exhibits high zinc ion migration and interfacial compatibility. TEMPO is added to this electrolyte at a concentration of 5-12 mmol / L to form a composite electrolyte 5 with redox regulation function. The molar concentration ratio of TEMPO to Zn(CF3SO3)2 is 1:170-1:400, with a preferred TEMPO concentration of 10 mmol / L and a Zn(CF3SO3)2 concentration of 2 mol / L to achieve a balance between interfacial regulation and electrolyte stability.

[0026] During battery discharge, zinc ions migrate to the surface of the negative electrode 4 and undergo reduction deposition. Locally uneven electric fields can easily induce differences in nucleation rates, leading to dendrite growth. TEMPO molecules, with their stable free radical structure, can form a charge buffer layer near the surface of the negative electrode 4. Their oxidized state can temporarily accept electrons to mitigate local potential fluctuations and reduce the interfacial charge density gradient, thereby promoting the dispersed deposition of zinc ions over a wider range, forming a zinc layer morphology with a uniform structure and low dendrite tendency. Furthermore, the microscopic interaction between TEMPO and the solvated zinc ions in an aqueous environment helps regulate the desolvation kinetics and enhance the order and adhesion of the initial nucleation.

[0027] During the charging stage, some deposited areas have poor electrical contact or delayed interfacial reactions, which can easily form irreversible "dead zinc" structures. The reduced state of TEMPO molecules can participate in the electron redistribution process near the interface, transferring local electrons to the inactive area of ​​the electrode, which helps to reactivate the stagnant zinc metal and allow it to re-participate in the reversible reaction process, thereby reducing zinc resource waste and delaying capacity decay. Overall, TEMPO completes the coordinated regulation of zinc dendrite inhibition and "dead zinc" activation in the redox cycle, effectively improving the reaction stability and interface sustainability of the zinc negative electrode, and laying the foundation for long-term and efficient operation of the battery.

[0028] In this embodiment, in addition to TEMPO dissolved in a concentration of 10 mmol / L, 3% by volume of glycerol is further added to the composite electrolyte 5 to form a solvent system together with water. Glycerol is a triol molecule with high polarity and low volatility, which plays multiple synergistic regulatory roles in the system: First, the glycerol molecule can react with Zn 2+ The ions form a stable solvated coordination structure, which helps to regulate the migration rate and spatial distribution of zinc ions and reduce the problem of uneven nucleation caused by the electric field gradient; secondly, glycerol molecules can be adsorbed on the electrode interface to form a dynamic buffer layer, inhibiting the Zn 2+ Thirdly, glycerol's viscosity and film-forming ability help mitigate electrolyte volatilization and solvent interface disturbances during cycling, improving the electrolyte's service life and overall system stability. Furthermore, glycerol and TEMPO exhibit no chemical reaction interference, maintaining good solubility and redox reversibility in solution, contributing to synergistic interfacial regulation of the zinc anode.

[0029] The Zn||MnO2 battery with TEMPO added to the electrolyte of this example and the Zn||MnO2 battery without TEMPO added to the electrolyte were subjected to 50 charge-discharge cycles to verify the effect of TEMPO in the composite electrolyte 5 on the interfacial deposition behavior of the zinc negative electrode. The only difference between the two groups of batteries was the addition of TEMPO; all other conditions were the same. After the 50 charge-discharge cycles, the negative electrode sheet 4 was disassembled and removed, and its surface morphology was characterized using a scanning electron microscope (SEM). Figure 2 shown. Figure 2 (a)- Figure 2 (c) is the SEM image of the negative electrode sheet 4 of the battery without adding TEMPO to the electrolyte, corresponding to the characterization results under the scale conditions of 5μm, 10μm and 20μm, respectively. It can be seen that under different magnifications, the zinc surface presents an irregular flaky structure with obvious dendritic protrusions, and local areas form stacking or peeling, indicating the presence of a large amount of "dead zinc" residue and dendrite deposition. In contrast, Figure 2 (d)- Figure 2 (f) is an SEM image of the battery negative electrode sheet 4 using the TEMPO system used in this example, also corresponding to the characterization results under 5μm, 10μm, and 20μm scale conditions. The image shows that the deposited zinc layer has a dense and smooth morphology, with no obvious dendrite structure. The surface particles are uniform in size, and the negative electrode sheet 4-electrolyte interface has good continuity. This difference verifies the role of TEMPO in regulating the interfacial electric field and zinc ion deposition process during charge and discharge, effectively mitigating dendrite formation and reactivating "dead zinc" areas, providing structural support for improving the stability and cycling performance of the zinc negative electrode.

[0030] like Figure 3 As shown in the figure, X-ray diffraction (XRD) analysis was performed on the zinc deposited layer after 50 cycles to evaluate the effect of different electrolyte systems on the structure of zinc deposited. The results showed that the zinc deposited layer formed in the control group showed obvious (002), (100) and (101) crystal plane preferential growth characteristics, accompanied by a certain intensity of basic zinc trifluoromethanesulfonate by-product diffraction peaks, reflecting the existence of structural disorder and side reaction accumulation in the deposition process. In contrast, the zinc deposited layer formed in the test group still maintained a pure zinc metal crystal structure, no obvious by-product peaks were detected, and the crystal plane orientation was more uniform. Quantitative analysis of crystal orientation further showed that the (002) and (101) crystal plane diffraction intensity ratio of the zinc deposited layer in the test group was 0.87, which was significantly higher than 0.53 in the control group. This difference indicates that the TEMPO additive regulates the zinc deposition path through reversible redox reactions during the electrochemical cycle, inhibits dendrite formation and promotes uniform and directional crystal growth, revealing its mechanistic role in eliminating "dead zinc" and regulating deposition behavior from a crystallographic perspective.

[0031] Furthermore, in the composite electrolyte 5 system used in this embodiment, the introduction of TEMPO helps to induce the formation of an interface structure layer mainly composed of ZnF2 and ZnO during the charge and discharge process of the zinc negative electrode. 2+ Driven by the electric field, CF3SO3 migrates to the negative electrode surface and undergoes reduction deposition. - Anions also accumulate at the interface, and their decomposition products can react with deposited zinc to form ZnF2; in addition, OH released by the electroreduction of water molecules - Ions can also react with Zn 2+ The adsorption capacity of TEMPO molecules at the interface and the electron release effect of their oxidized structure help to regulate the electron density and local potential distribution on the negative electrode surface, delay instantaneous zinc reduction, and enhance ZnO. 2+ The synergistic reaction efficiency between the ZnF2 and the interface reactants is improved, thereby promoting the stable nucleation and uniform deposition of interface products. The formation process of this interface structure layer does not require the introduction of additional interface modifiers or gas protection conditions. It can be generated in situ during the operation of the battery and has good structural density and stability. Among them, ZnF2 has electronic insulation and a certain degree of ion permeability, which effectively blocks the direct contact between metallic zinc and the active components in the electrolyte and inhibits side reactions; ZnO provides strong interface passivation and mechanical support, which can alleviate the risk of dendrite-induced peeling damage. The product layer synergistically constructed by the two has high stability and self-healing ability during the cycle, which helps to improve the reaction selectivity of the zinc negative electrode surface, the consistency of the deposition morphology and the overall interface stability, and provide support for the long-life operation of the battery.

[0032] The composite electrolyte 5 with TEMPO added also has excellent electrochemical stability. Its electrochemical stability window can reach above 2.5V, which can support the stable operation of aqueous zinc-ion batteries in the operating voltage range of 1.8-2.3V. The working density of aqueous zinc-ion batteries is 0.1-5mA / cm 2 This performance improvement is mainly due to the synergistic effect of TEMPO's nitroxide radical structure at the positive and negative electrode interfaces: on the positive electrode side, TEMPO can capture residual active oxygen species in the electrolyte (such as hydroxyl radicals ·OH, superoxide anions O2 - ), inhibiting the oxygen evolution reaction, thereby moving the oxygen evolution potential positively; on the negative electrode side, the reduction product TEMPO-H after TEMPO accepts electrons and protons can react with Zn 2+ The reaction forms a ZnF2 / ZnO interfacial structure layer, effectively blocking water molecules from approaching the zinc surface, inhibiting the hydrogen evolution reaction and shifting the hydrogen evolution potential negatively. This bidirectional regulation mechanism expands the electrochemical window, enabling stable battery operation at higher voltages, helping to increase energy density and enhance overall operational safety.

[0033] The present embodiment tests the electrochemical performance of aqueous zinc ion batteries to verify the regulating effect of the TEMPO additive proposed in the application in aqueous zinc ion batteries. The test group battery electrolyte contains 2 mol / L Zn(CF3SO3)2+10 mmol / L TEMPO (marked as ZF+TEMPO in the figure), and the control group battery electrolyte is the basic electrolyte containing only 2 mol / L Zn(CF3SO3)2 (marked as ZF in the figure).

[0034] In order to verify the influence of TEMPO on the formation of the product layer of the zinc negative electrode interface in the composite electrolyte 5, the present embodiment performs X-ray photoelectron spectroscopy (XPS) analysis on the surface of the zinc negative electrode after cycling, as shown in Figure 4 The zinc symmetric half-cell (Zn|| electrolyte|| Zn) is tested, and the test conditions are a current density of 2 mA / cm 2 , a capacity of 2 mAh / cm 2 , and a cycle time of 100 hours. Figure 4 (a) and Figure 4 (c) are XPS spectra of C1s orbitals. The results show that the control group battery mainly exists typical bonding peaks such as C-C, O-C=C and -CF3. In contrast, the intensity of the above bonding peaks in the test group battery is significantly enhanced, indicating that TEMPO participates in the formation of a more complex and stable organic interface structure. Figure 4 (b) and Figure 4 (d) are XPS spectra of Zn 2p orbitals. In the control group, only the characteristic peak of Zn 0 is observed, indicating that the electrode surface is basically in the state of metallic zinc. In the test group, the characteristic peaks of ZnO and ZnF2 appear at the same time, indicating that TEMPO induces the formation of a stable ZnF2 / ZnO interface structure layer during charging and discharging. This structure helps to improve the chemical stability and electronic barrier ability of the zinc electrode interface, inhibits the occurrence of side reactions, and provides a foundation for subsequent stable electrochemical performance.

[0035] Under the condition of a constant overpotential of-150 mV, the electrolyte with or without TEMPO additive is subjected to chronoamperometry (CA) test to explore the nucleation and deposition behavior of zinc ions, as shown in Figure 5As shown. The test used a Zn||Zn symmetric battery and recorded the current-time response curves under different electrolyte systems. The results showed that the current response in the control group decayed rapidly, indicating that the nucleation during zinc deposition was more intense and uneven, which was limited by the interface ion transport and local electric field perturbations, and easily induced dendrite growth. In the test group, the curve in the figure tended to be stable, the initial current change was gentle, and then a stable output state was presented, indicating that zinc ions achieved more uniform nucleation and deposition on the electrode surface. This difference reflects the regulatory role of TEMPO in the electrochemical deposition process. As a reversible redox mediator, TEMPO can construct a dynamic electron transfer path on the surface of the negative electrode 4, buffer local charge density changes, eliminate electron blockage in the "dead zinc" area, and induce the formation of a dense, uniform and continuous metal zinc deposition layer, thereby providing a basis for the stable operation of subsequent electrochemical cycles.

[0036] like Figure 6 To further investigate the effect of the TEMPO additive in composite electrolyte 5 on zinc deposition behavior, cyclic voltammetry (CV) tests were conducted using copper foil as the working electrode in a Zn||Cu half-cell. The deposition and stripping behaviors of zinc on copper foil under different electrolyte conditions were compared. The test results showed that during the scan, the nucleation overpotential (NOP) in the test group's composite electrolyte 5 system was higher than that in the control group, with a difference of 86.7 mV. This indicates that in the presence of TEMPO, the nucleation process of zinc ions requires overcoming a higher electrochemical energy barrier. A higher NOP indicates a smaller zinc nucleation radius and a greater nucleation density, which in turn promotes the formation of a fine and uniformly distributed deposit structure. These results demonstrate that the TEMPO additive effectively promotes uniform zinc nucleation and deposition on copper substrates, inhibiting dendrite growth and providing key support for improving the ability to control electrode interface morphology.

[0037] like Figure 7 As shown, linear sweep voltammetry (LSV) tests were also conducted using Zn||Cu half-cells to evaluate the electrochemical stability under different electrolyte conditions. The scan rate was 0.1 mV / s, and the electrochemical stability window (ESW) of the electrolyte was determined. The test results showed that the ESW of the control electrolyte was 2.20 V, while the ESW of the test electrolyte widened to 2.65 V with the introduction of the TEMPO additive. In contrast, the ESW of composite electrolyte 5 expanded by approximately 20.5%, indicating that TEMPO can effectively improve the electrolyte's resistance to decomposition at high voltages, inhibit hydrogen evolution and side reactions, and enhance the safety and interfacial stability of the battery system.

[0038] like Figure 8As shown, electrochemical impedance spectroscopy (EIS) measurements were performed using a Zn||Cu half-cell to eliminate interference from the cathode reaction and focus on analyzing the dynamic behavior of the anode interface. Initially, the interface resistance of both systems was 25Ω, indicating similar interface states. After 50 charge-discharge cycles, the interface impedance of the test group was significantly lower than that of the control group, indicating that the interface conductivity remained good. This difference is attributed to TEMPO's ability to suppress the accumulation of "dead zinc" and byproducts through a reversible redox mechanism during the electrochemical process, maintaining the stability and permeability of the electrode interface, further demonstrating its positive contribution to regulating zinc deposition behavior and improving cycling stability.

[0039] like Figure 9 To evaluate the inhibitory effect of TEMPO on the self-corrosion behavior of the zinc anode, linear polarization tests were conducted using a Zn||Zn symmetric cell. The corrosion current density in two electrolyte systems was analyzed based on Tafel fitting. The test results showed that the corrosion current density of the zinc electrode in the test group was significantly lower than that in the control group, decreasing by 16.8%. This indicates that the introduction of TEMPO reduced the self-corrosion rate of zinc and improved the chemical stability of the interface. This inhibitory effect is primarily attributed to the ability of TEMPO molecules to neutralize corrosion-inducing factors (such as reactive oxygen species) through reversible electron transfer reactions, thereby weakening the localized corrosion driver. Furthermore, TEMPO forms a dynamically adsorbed protective layer on the zinc surface, effectively blocking direct contact between water molecules in the electrolyte and the zinc surface, slowing the corrosion process.

[0040] Example 2: Based on Example 1, this example further introduces a periodic current control strategy to suppress the local electric field concentration phenomenon at the zinc negative electrode interface, improve the uniformity of zinc ion deposition, thereby reducing the risk of dendrite growth and "dead zinc" generation, and improving the long-cycle stability of aqueous zinc ion batteries.

[0041] After the battery is assembled and filled with liquid and left to stand, a constant current source with programmable control capability is used for charging control. The charging process no longer uses the traditional single constant current method, but instead sets alternating current input in the forward and reverse phases in each charging cycle. Specifically, the total length of each cycle is 15 minutes, with 1mA / cm applied for the first 10 minutes. 2 The forward current was then switched to -0.1 mA / cm for 5 minutes to drive the normal zinc ion deposition process. 2The micro-current reverse mode is used to weaken the electric field enhancement trend caused by charge accumulation and morphological protrusions on the negative electrode surface, inducing relaxation and trimming of the primary dendrite area. This positive and negative alternating current control method can be automatically switched through the program parameters set by the microcontroller, and the total cycle duration and current density of each stage can be adjusted as needed to adapt to different load conditions or operating strategies. Through the periodic alternation of positive and negative currents, the dynamic migration and diffusion of zinc ions between deposition and dissolution can be promoted, thereby gradually building a denser and equipotential deposition structure in multiple cycles, and improving the uniformity and continuity of the negative electrode surface. This strategy forms a synergistic mechanism with the charge buffering effect provided by TEMPO molecules at the interface, which helps to maintain the deposition stability of zinc ions during multiple cycles of charge and discharge, and reduces the risk of dendrite initiation and "dead zinc" formation caused by local electric field concentration.

[0042] Example 3: This application also proposes a method for preparing an aqueous zinc ion battery based on TEMPO regulation, which comprises the following steps: S1. Prepare an aqueous solution of Zn(CF3SO3)2 as the basic electrolyte; at room temperature (20-25°C), weigh 7.27g of Zn(CF3SO3)2 powder and slowly add it to 10mL of deionized water and stir. The stirring method is magnetic stirring, the speed is set to 300-500rpm, and stirring is continued for 10-15 minutes until the powder is completely dissolved and the solution is clear and transparent. During the operation, water evaporation and the introduction of impurities should be avoided. The concentration of Zn(CF3SO3)2 in the obtained solution is 2mol / L, which serves as the basic electrolyte for the subsequent electrolyte system. Zn(CF3SO3)2 has high solubility and ionic conductivity, and is suitable for constructing medium and high concentration electrolyte systems required for aqueous zinc ion batteries. At the same time, Zn in this system 2+ It has good hydration ability and migration rate, which helps to improve the transport efficiency of zinc ions and the interface uniformity of the deposition process.

[0043] S2. Add TEMPO to the base electrolyte to form composite electrolyte 5. At room temperature (20-25°C), weigh 15.625 mg of TEMPO powder and slowly add it to 10 mL of the Zn(CF3SO3)2 base electrolyte prepared according to step S1, avoiding local aggregation. Stir using a magnetic stirrer at 300-500 rpm for 10-15 minutes until the powder is completely dissolved and the solution is clear. After dissolution, let it stand for 10 minutes to obtain a uniform and stable composite electrolyte 5 with a TEMPO concentration of 10 mmol / L.

[0044] Furthermore, to improve the dispersibility of TEMPO in the aqueous system, a solvent pre-dissolution method can be used. The specific operation is: 15.625mg of TEMPO is pre-dissolved in 0.3-0.5mL of ethanol or acetone to form a uniform TEMPO organic solution, which is then added dropwise to the Zn(CF3SO3)2 based electrolyte while stirring until the mixture becomes clear. This treatment method helps to reduce the local aggregation tendency of TEMPO in the aqueous solution and improve its uniformity of dispersion in the overall electrolyte, thereby accelerating its onset speed in participating in the redox reaction at the electrode interface and improving its interface regulation efficiency.

[0045] S3, sequentially placing the positive electrode sheet 3, the separator 2 and the negative electrode sheet 4 inside the housing 1; taking the prepared positive electrode sheet 3, the negative electrode sheet 4 and the glass fiber separator 2, and placing them in the battery housing 1 in a stacked manner for assembly, thereby constructing a basic battery unit, such as Figure 10 As shown. First, place the positive electrode sheet 3 on the bottom of the housing 1, with its active material coating facing upward. Then, cut the separator 2 to a size larger than the electrode sheet and smaller than the housing 1, and center it on the surface of the positive electrode sheet 3, avoiding wrinkles or displacement. Next, stack the zinc negative electrode sheet 4 on top of the separator 2, facing the positive electrode sheet 3, to form a complete stacked structure. Before assembly, wipe the surface of the negative electrode sheet 4 with anhydrous ethanol and optionally mechanically polish it to remove the zinc oxide layer and any remaining particulates, thereby improving its surface cleanliness and wettability with the electrolyte.

[0046] S4. Inject the composite electrolyte 5 into the housing 1 and seal the package to obtain an aqueous zinc ion battery. After the three-layer basic battery unit is assembled, 10 mL of TEMPO composite electrolyte 5 is injected into the battery housing 1. During the injection process, it is preferably injected slowly from the edge of the housing 1 to ensure that the composite electrolyte 5 can fully penetrate along the gap between the diaphragm 2 and the electrode assembly. The injection rate should be controlled during the injection process to avoid splashing of the composite electrolyte 5 or the introduction of bubbles. After the electrolyte fully wets the diaphragm 2 and the surface of the electrode, the housing 1 is structurally sealed so that the positive electrode shell and the negative electrode shell are tightly fitted to form a closed structure to prevent leakage of the composite electrolyte 5. Before packaging, the assembly can be gently shaken for a few seconds to help expel entrained gas in advance and avoid dry area residue affecting the uniformity of subsequent electrochemical reactions. After packaging, the battery should be aged at room temperature for 12-24 hours to allow the composite electrolyte 5 to fully diffuse and redistribute in the internal structure, enhance the wettability and ion channel stability between the diaphragm 2 and the electrode sheet interface, and improve the consistency of the overall interface structure and the repeatability of the initial electrochemical performance.

[0047] After the composite electrolyte 5 is injected and before packaging, the structure inside the shell 1 can be treated with ultraviolet light to enhance the interfacial effect of the TEMPO additive in the composite electrolyte 5. During the treatment, the battery to be packaged is placed in a UV light box and irradiated with a low-pressure UV light source with a wavelength of 254nm or 365nm. The duration is controlled to be 5-10 minutes and the irradiation intensity is maintained at 0.5-2.0mW / cm 2 . To prevent the liquid surface disturbance from causing component stratification or activity decay, the battery housing 1 should be kept stationary during the irradiation process. Ultraviolet light can induce TEMPO molecules to enter an excited state from the ground state, enhance the electronic activity and interfacial reactivity of their free radical structure, and promote them to form reversible adsorption or weak complex structures on the surface of the zinc negative electrode sheet 4, thereby accelerating their induction of zinc ion nucleation behavior in the initial stage. This treatment measure helps to achieve crystal orientation regulation and deposition uniformity in the early stage of nucleation, thereby effectively improving interface consistency and electrochemical stability during the first few cycles of charge and discharge.

[0048] Furthermore, in order to improve the chemical stability of TEMPO in the composite electrolyte 5, a buffer solution can be introduced during its addition process to adjust the pH value of the composite electrolyte 5 to a weak neutral range. Specifically, before TEMPO dissolves, a phosphate buffer pair (such as NaH2PO4 and Na2HPO4) is introduced into the base electrolyte, and the pH of the base electrolyte is controlled within the range of 6.5-7.2 by adjusting the molar ratio of the two. The selected buffer solution should have good water solubility, high resistance to Zn 2+ There is no coordination interference and it is electrochemically inert within the battery operating voltage range. The purpose of introducing the buffer system is to create a relatively stable solution environment to inhibit the possible spontaneous degradation, reduction consumption or reaction of TEMPO with by-products in the solution (such as OH - , ROH, etc.), thus reducing the risk of activity loss during the cycle. A weakly neutral environment helps maintain the stability of the free radical structure of TEMPO, preventing it from breaking due to protonation or alkaline hydrolysis, thereby ensuring that it can continue to play its interface regulation and reaction induction functions under long-term circulation conditions. In addition, a stable pH environment can also inhibit the Zn 2+ The hydrolysis and deposition of alkaline by-products further improve the controllability of the interfacial reaction and the durability of the electrolyte system.

[0049] To compare the effects of different electrolyte systems on battery performance, cycling performance tests were conducted on the aqueous zinc-ion batteries prepared in this example. These batteries were Zn||MnO2 full cells. The control and test group batteries used the same electrolyte as described in Example 1.

[0050] Cyclic voltammetry tests were performed on different electrolyte systems to verify the redox activity of TEMPO. The results are as follows: Figure 11As shown in the figure. The curve shows that the oxidation peak of the control electrolyte is 1.68V, and the reduction peaks are 1.12V and 1.3V; the oxidation peak of the test group is 1.69V, and the reduction peaks are 1.16V and 1.31V. Compared with the control electrolyte, the test group composite electrolyte 5 shows a smaller potential difference between the oxidation / reduction peaks, indicating that TEMPO has good electrochemical reversibility in an aqueous environment and can stably participate in the electron transfer process, confirming that it can continuously play the dual functions of interface regulation and reaction activation in the battery system.

[0051] like Figure 12 To evaluate the impact of different electrolyte systems on battery rate performance, Zn||MnO2 full cells were subjected to rate charge-discharge tests using test and control electrolytes. The tests were conducted at seven current densities, 0.5, 1, 2, 5, 2, 1, and 0.5 A / g, with five cycles per current density. The capacity retention and reversibility of the cells at different current densities were examined. The test results showed that the specific capacity of the test group cells consistently outperformed that of the control cells across the full current density range. In particular, at high current densities (e.g., 5 A / g), the discharge capacity remained high, demonstrating excellent rate responsiveness and fast reaction kinetics. When the current density was reduced back to its initial value of 0.5 A / g, the specific capacity of the test group cells was effectively restored, demonstrating excellent structural stability and interfacial reversibility. This demonstrates that the TEMPO additive promotes zinc ion migration, inhibits interfacial polarization, and improves electrode reaction kinetics.

[0052] like Figure 13As shown, Zn||MnO2 full cells were subjected to constant-current charge-discharge tests at a current density of 4 A / g to evaluate the effect of the TEMPO additive on the long-term cycling stability of the cells. The test was repeated for 1500 cycles, with the specific capacity and coulombic efficiency simultaneously recorded to comprehensively reflect the reversibility and structural stability of the cells. The results showed that the control group using the basic electrolyte exhibited continuous capacity decay during cycling, dropping from an initial capacity of 136.4 mAh / g to approximately 20 mAh / g, with a capacity retention rate of less than 15%. Significant fluctuations also occurred in the later stages, reflecting unstable interfacial structures and severe accumulation of side reactions. In contrast, the test group using composite electrolyte 5 containing the TEMPO additive exhibited even better stability and durability, with an initial specific capacity of 138.6 mAh / g and a retained specific capacity of 65 mAh / g after 1500 cycles, representing a capacity retention rate of nearly 47%. Furthermore, the TEMPO system maintained a coulombic efficiency close to 100% throughout the entire cycling process, demonstrating its excellent electrochemical reversibility and interfacial reaction control capabilities. The experimental results further prove that TEMPO continues to play an interface regulation role during long-term operation through its reversible redox properties, effectively inhibiting zinc dendrite growth and by-product deposition, delaying the electrode attenuation process, and providing key guarantees for the highly stable operation of aqueous zinc-ion batteries.

[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A TEMPO-regulated aqueous zinc-ion battery comprising a housing, an electrode assembly, a diaphragm, and an electrolyte, wherein the electrode assembly comprises a positive electrode sheet and a negative electrode sheet disposed at both ends of the housing, the diaphragm being disposed between the positive electrode sheet and the negative electrode sheet, the electrolyte filling the housing, and the electrolyte simultaneously infiltrating the surface of the electrode assembly and the diaphragm, characterized in that: TEMPO is dissolved in the electrolyte.

2. The aqueous zinc ion battery based on TEMPO regulation according to claim 1, characterized in that: The concentration of TEMPO in the electrolyte is 5-12 mmol / L.

3. The aqueous zinc ion battery based on TEMPO regulation according to claim 2, characterized in that: In the electrolyte, Zn(CF3SO3)2 is used as the electrolyte salt, and the molar concentration ratio of the TEMPO to the Zn(CF3SO3)2 is 1:170-1:

400.

4. The aqueous zinc ion battery based on TEMPO regulation according to claim 3, characterized in that: The positive electrode sheet is made of manganese dioxide material, the negative electrode sheet is made of metal zinc, and the separator is made of glass fiber material.

5. The aqueous zinc ion battery based on TEMPO regulation according to claim 4, characterized in that: The surface area of ​​the negative electrode sheet has an interface structure layer rich in ZnF2 and ZnO.

6. The aqueous zinc ion battery based on TEMPO regulation according to claim 5, characterized in that: The working density of the aqueous zinc ion battery is 0.1-5 mA / cm 2 .

7. A method for preparing an aqueous zinc ion battery based on TEMPO regulation, characterized in that: The method comprises the following steps: S1. Prepare an aqueous solution of Zn(CF3SO3)2 as the basic electrolyte; S2, adding TEMPO to the basic electrolyte to form a composite electrolyte; S3, sequentially placing the positive electrode sheet, the separator, and the negative electrode sheet inside the housing; S4. Injecting the composite electrolyte into the shell, and sealing and packaging it to obtain the aqueous zinc ion battery.

8. The method for preparing an aqueous zinc ion battery based on TEMPO regulation according to claim 7, wherein: In S2, the TEMPO is pre-dissolved in ethanol or acetone as a solvent.

9. The method for preparing an aqueous zinc ion battery based on TEMPO regulation according to claim 8, characterized in that: In S3, before the negative electrode sheet is placed inside the shell, the surface of the negative electrode sheet is wiped with anhydrous ethanol.

10. The method for preparing an aqueous zinc ion battery based on TEMPO regulation according to claim 9, characterized in that: Before the sealing and packaging in S4, the shell into which the composite electrolyte is injected is subjected to ultraviolet light treatment.

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