Aqueous zinc battery electrolyte, preparation method and aqueous zinc battery

Abstract

The application discloses a water-based zinc battery electrolyte, a preparation method and a water-based zinc battery, and aims to solve the problems of dendrite / hydrogen evolution of the water-based zinc battery, poor low-temperature performance and difficulty in treating medical wastewater. The electrolyte comprises a basic electrolyte and 2-methyl-5-nitroimidazole-1-ethanol (photolysis directional cleavage of heterocycle, retention of -NO2 and -OH) subjected to photolysis by natural light. In the preparation, the additive is dissolved in the basic electrolyte and subjected to photolysis treatment. The electrolyte can optimize the solvation structure of zinc ions, promote ion deintercalation and inhibit hydrogen evolution. The Zn / / Zn symmetrical battery is stably cycled for more than 5400h / 2000h at 1 / 20 mA*cm-2, respectively, the full battery is cycled for more than 1000 times at room temperature, and the capacity retention rate is high at -10 DEG C. The raw material can be taken from medical residual wastewater, the preparation is simple, the cost is low, the performance is improved, and the environmental protection and economy are coordinated.

Description

Technical Field

[0001] This invention relates to new energy and electrochemical technology, and in particular to an aqueous zinc battery electrolyte, its preparation method, and an aqueous zinc battery. Background Technology

[0002] Lithium-ion batteries, as the dominant energy storage technology in mobile phones, electric vehicles, and other fields, have gained widespread application due to their advantages such as high energy density, high voltage, and long cycle life. However, due to the increasing scarcity of lithium resources, persistent safety concerns, and the fact that performance development is gradually approaching its theoretical limits, their large-scale promotion and cost control face significant pressure.

[0003] Against this backdrop, aqueous zinc-ion batteries have shown significant potential, possessing advantages such as environmental friendliness, high safety, and low cost. In particular, relying on the characteristics of low redox potential, high specific capacity, and safe aqueous electrolyte, they present broad application prospects in fields such as small electronic devices, grid energy storage, renewable energy integration, and electric vehicles.

[0004] However, zinc anodes are prone to hydrogen evolution corrosion, zinc dendrite growth, and short circuits in aqueous electrolytes, which severely hinders the large-scale promotion and practical application of this system. Meanwhile, the narrow electrochemical window of aqueous electrolytes (typically not exceeding 2.0V) limits the battery's energy density, and electrolyte freezing at low temperatures also restricts the battery's practical application.

[0005] Furthermore, the application of zinc batteries currently faces challenges such as difficulty in reducing costs and increasing efficiency, and an imperfect green recycling system. Treating and reusing residual wastewater generated in pharmaceutical industrial production as an electrolyte for aqueous zinc batteries could effectively solve problems such as the difficulty in degrading pharmaceutical wastewater, the high manufacturing cost of aqueous zinc batteries, and the poor performance of zinc batteries.

[0006] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] The main objective of this invention is to overcome the deficiencies in the above-mentioned background technology and provide an aqueous zinc battery electrolyte, a preparation method, and an aqueous zinc battery.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] An aqueous zinc battery electrolyte comprises a base electrolyte and 2-methyl-5-nitroimidazole-1-ethanol, wherein the 2-methyl-5-nitroimidazole-1-ethanol is subjected to photolysis treatment to directionally cleave the 2-methyl-5-nitroimidazole-1-ethanol heterocycle while retaining the nitro (-NO2) and hydroxyl (-OH) functional groups.

[0010] Further, the concentration of the 2-methyl-5-nitroimidazole-1-ethanol is from 2.5 mM to 10 mM, preferably 5 mM.

[0011] Furthermore, the basic electrolyte comprises ZnSO4 and deionized water.

[0012] Furthermore, the concentration of ZnSO4 is 2 M.

[0013] Furthermore, the photolysis treatment is a natural light photolysis treatment, and the time is more than 10 days.

[0014] A method for preparing the aqueous zinc battery electrolyte includes the following steps:

[0015] 2-Methyl-5-nitroimidazole-1-ethanol was added to the basic electrolyte and dissolved to obtain a mixed solution;

[0016] The mixed solution is subjected to photolysis treatment to directionally cleave the 2-methyl-5-nitroimidazole-1-ethanol heterocycle while retaining the nitro (-NO2) and hydroxyl (-OH) functional groups, to obtain a photolyzed aqueous zinc battery electrolyte; preferably, the photolysis treatment involves exposing the mixed solution to natural light for more than 10 days.

[0017] An aqueous zinc battery includes a positive electrode, a negative electrode, a separator, and the aqueous zinc battery electrolyte.

[0018] Furthermore, the positive electrode sheet includes a vanadium-based positive electrode material.

[0019] Furthermore, the vanadium-based cathode material is NaV3O8·1.5H2O.

[0020] Furthermore, the negative electrode sheet is zinc foil.

[0021] The present invention has the following beneficial effects:

[0022] This invention proposes an aqueous zinc battery electrolyte and its preparation method. The method involves adding the antibiotic 2-methyl-5-nitroimidazole-1-ethanol to a base electrolyte, followed by photolysis to obtain a high-performance aqueous zinc battery electrolyte. This electrolyte improves the solvation structure of zinc ions, promotes rapid zinc ion insertion / extraction, enhances reaction kinetics, reduces active water content, and inhibits hydrogen evolution corrosion. After photolysis, polar functional groups are enriched on the zinc anode surface, guiding uniform zinc deposition and optimizing SEI layer formation. Experiments show that the regenerated electrolyte Zn / / Zn symmetric battery achieves stable cycling for over 5400 h and 2000 h under conditions of 1 mA cm⁻² / 0.5 mAh cm⁻² and 20 mA cm⁻² / 5 mAh cm⁻², respectively, significantly outperforming the base electrolyte. The full cell can cycle stably for more than 1,000 times at room temperature, and its performance at low temperature (-10℃) is also improved, indicating that the zinc battery electrolyte prepared by photolysis of 2-methyl-5-nitroimidazole-1-ethanol additive effectively improves the zinc ion insertion / extraction efficiency and charge / discharge capacity, and enhances the battery cycle stability.

[0023] Compared with the prior art, the significant advantages of the present invention are specifically reflected in the following aspects:

[0024] 1) Photoinduced directional cleavage of the 2-methyl-5-nitroimidazole-1-ethanol heterocycle eliminated the risk of crystallization while retaining the -NO2 and -OH polar functional groups. The strong interaction between -NO2 and the zinc surface triggered chemisorption, assisting Zn... 2 + Uniform deposition on the zinc anode surface leads to the rapid formation of a dense and stable SEI layer, facilitating subsequent rapid ion insertion and extraction.

[0025] 2) -OH and Zn 2+ Water molecules in the solvation sheath form intermolecular hydrogen bonds, reducing the strength of the solvation sheath and assisting Zn 2+ Rapid desolvation effectively enhances ion transport kinetics, while reconstructing the electrolyte hydrogen bond network suppresses hydrogen evolution reaction and dendrite growth.

[0026] 3) By disrupting the hydrogen bond network between water molecules, the photolyzed 2-methyl-5-nitroimidazole-1-ethanol additive electrolyte has a lower freezing point and can maintain a higher ionic conductivity at low temperatures, thereby improving the low-temperature performance of the battery.

[0027] 4) The preparation process is simple and feasible. It only requires adding trace amounts of 2-methyl-5-nitroimidazole-1-ethanol as an additive to the electrolyte according to the required concentration, and then assembling the battery after full exposure under natural light.

[0028] 5) The raw materials used are inexpensive and meet the actual environmental and economic needs of residual wastewater degradation and reuse in antibiotic pharmaceutical production.

[0029] This invention utilizes photo-induced degradation of the pharmaceutical additive 2-methyl-5-nitroimidazole-1-ethanol in a basic aqueous electrolyte environment, thereby improving key properties such as the electrolyte's ionic conductivity and expanding its electrochemical window. Simultaneously, it promotes rapid zinc ion migration, inhibits hydrogen evolution side reactions, and participates in the construction of a stable SEI layer, significantly enhancing the battery's cycle performance and coulombic efficiency. Under low-temperature conditions, the components obtained from the photodegradation of 2-methyl-5-nitroimidazole-1-ethanol can regulate the hydrogen bond network of water molecules, helping the electrolyte maintain good ionic conductivity and interfacial stability. In summary, this invention uses the recalcitrant pharmaceutical component 2-methyl-5-nitroimidazole-1-ethanol as an electrolyte additive, achieving the recycling of pharmaceutical residues in aqueous solutions into aqueous zinc battery electrolytes through a simple and easy-to-implement photodegradation method. This optimizes zinc battery performance while simultaneously achieving efficient treatment of industrial pollution and large-scale, high-efficiency zinc battery production, which is of great significance for improving the performance and practical application of aqueous zinc batteries.

[0030] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description

[0031] Figure 1 These are contact angle images of the electrolytes in Comparative Example 1 and Examples 1-3 on the zinc sheet surface at 0s.

[0032] Figure 2 For the Zn / / Zn symmetric cells of Example 2 and Comparative Example 1, at 1 mA cm⁻¹ -2 0.5 mAh cm -2 Constant current charge-discharge curves under the specified conditions;

[0033] Figure 3 For the Zn / / Zn symmetric cells of Example 2 and Comparative Example 1, at 20 mA cm⁻¹ -2 5 mAh cm -2 Constant current charge-discharge curves under the specified conditions;

[0034] Figure 4 For the Zn / / Cu asymmetric cells of Example 2 and Comparative Example 1, at 1 mA cm⁻¹ -2 Cycle count-Coulomb efficiency plot at current density;

[0035] Figure 5 For Example 2 and Comparative Example 1, at 20 mA cm -2 In-situ optical microscope image of Zn coating at current density (scale bar 120 μm).

[0036] Figure 6 The Zn / / NaV3O8 full cells of Example 2 and Comparative Example 1 were measured at 25°C with a capacity of 2 A g.-1 Graph of constant current charge-discharge long-cycle performance under certain conditions;

[0037] Figure 7 For the Zn / / NaV3O8 full cells of Example 2 and Comparative Example 1, 1 A g at -10°C -1 The constant current charge-discharge long-cycle performance under certain conditions is shown in the figure. Detailed Implementation

[0038] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0039] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for fixing, coupling, or communication.

[0040] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0042] This invention aims to address the problems of zinc dendrite growth, hydrogen evolution corrosion, and poor low-temperature performance in aqueous zinc batteries, as well as the industry pain points of difficult degradation of residual wastewater from antibiotic and pharmaceutical production and high battery manufacturing costs. The invention proposes to add 2-methyl-5-nitroimidazole-1-ethanol to a 2M ZnSO4 base electrolyte and obtain a high-performance electrolyte through photolysis under natural light (directional cleavage of heterocyclic rings while retaining -NO2 and -OH). This method can significantly improve the cycle stability and low-temperature performance of the battery, while realizing the resource utilization of wastewater. Moreover, the preparation process is simple and low-cost.

[0043] This invention provides an aqueous zinc battery electrolyte, comprising a base electrolyte and 2-methyl-5-nitroimidazole-1-ethanol, wherein the 2-methyl-5-nitroimidazole-1-ethanol is subjected to photolysis treatment to directionally cleave the 2-methyl-5-nitroimidazole-1-ethanol heterocycle while retaining the nitro (-NO2) and hydroxyl (-OH) functional groups.

[0044] 2-Methyl-5-nitroimidazole-1-ethanol, its molecular formula is shown below:

[0045] .

[0046] In some embodiments, the concentration of the 2-methyl-5-nitroimidazole-1-ethanol is from 2.5 mM to 10 mM, preferably 5 mM.

[0047] In some embodiments, the base electrolyte comprises ZnSO4 and deionized water.

[0048] In some embodiments, the concentration of ZnSO4 is 2 M.

[0049] In some embodiments, the photolysis treatment is natural light photolysis treatment for more than 10 days. It is understood that irradiation with a xenon lamp that has similar spectral characteristics to natural light can also be used, or irradiation with a composite light source combining a low-power ultraviolet lamp and a visible LED lamp can also achieve the same photolysis treatment effect, that is, the directional cleavage of the heterocyclic structure of 2-methyl-5-nitroimidazole-1-ethanol while retaining the nitro (-NO2) and hydroxyl (-OH) functional groups therein.

[0050] A method for preparing the aqueous zinc battery electrolyte includes the following steps:

[0051] 2-Methyl-5-nitroimidazole-1-ethanol was added to the basic electrolyte and dissolved to obtain a mixed solution;

[0052] The mixed solution is subjected to photolysis treatment to directionally cleave the 2-methyl-5-nitroimidazole-1-ethanol heterocycle while retaining the nitro (-NO2) and hydroxyl (-OH) functional groups, to obtain a photolyzed aqueous zinc battery electrolyte; preferably, the photolysis treatment involves exposing the mixed solution to natural light for more than 10 days.

[0053] An aqueous zinc battery includes a positive electrode, a negative electrode, a separator, and the aqueous zinc battery electrolyte.

[0054] In some embodiments, the positive electrode comprises a vanadium-based positive electrode material.

[0055] In some embodiments, the vanadium-based cathode material is NaV3O8·1.5H2O.

[0056] In some embodiments, the negative electrode is zinc foil.

[0057] In some embodiments, the specific steps for preparing the aqueous zinc battery electrolyte are as follows:

[0058] Step 1: Preparation of NaV3O8·1.5H2O cathode material: 0.3g of vanadium pentoxide was dissolved in 10 mL of 2 M sodium chloride solution. After stirring continuously for 72 h, the solution was centrifuged at 8000 rpm and washed three times with deionized water. After washing with ethanol, the lower layer was collected and dried in an oven at 60 ℃ for 12 h to obtain NaV3O8·1.5H2O material.

[0059] Step 2: Preparation of sodium vanadate positive electrode sheet. The active material (NaV3O8·1.5H2O), binder (PVDF), and conductive agent (conductive carbon powder) are added to a mortar and mixed thoroughly. NMP solution is then added to the mortar and mixed until the slurry is smooth and fine. This slurry is poured onto the surface of a current collector (Ti foil). A 25 μm thick scraper is used to smooth the slurry on the Ti foil surface. The slurry is then dried in a 60℃ oven for 12 h. Finally, the slurry is stamped into 12 mm diameter discs using an electrode stamping machine, with an active material loading of 1.7~2.2 mg / cm³. -2 It is intended to be used as a positive electrode sheet;

[0060] Step 3: Prepare zinc negative electrode sheet. Cut zinc foil with a thickness of 100 μm into circular sheets with a diameter of 12 mm. Pour the circular sheets into anhydrous ethanol for ultrasonic cleaning, and dry them to use as negative electrode sheets.

[0061] Step 4: Prepare the electrolyte. Use 2M ZnSO4 electrolyte as the base electrolyte and add the antibiotic additive 2-methyl-5-nitroimidazole-1-ethanol. Stir until the additive is completely dissolved, then transfer the solution and expose it to natural light for 10 days or more.

[0062] Step 5: Assemble the button cell battery to be tested;

[0063] (1) Assemble the Zn / / Zn symmetrical battery in the following order: positive electrode shell, zinc electrode, separator, electrolyte, zinc electrode, gasket, spring sheet, negative electrode shell. Use a tablet press to compact and encapsulate the battery for subsequent testing.

[0064] (2) Assemble the Zn / / NaV3O8 full cell in the following order: positive electrode shell, positive electrode plate, separator, electrolyte, negative electrode plate, gasket, spring sheet, and negative electrode shell. Use a press to compact and seal the cell for subsequent testing.

[0065] The aqueous zinc battery electrolyte, preparation method, and aqueous zinc battery proposed in this invention have the following main advantages: First, photo-induced directional cleavage of the 2-methyl-5-nitroimidazole-1-ethanol heterocycle can be achieved, eliminating the risk of crystallization while precisely retaining the polar functional groups of nitro (-NO2) and hydroxyl (-OH). Among them, -NO2 can strongly interact with the zinc surface and initiate chemisorption, assisting Zn²⁺ to be uniformly deposited on the zinc anode surface, thereby rapidly generating a dense and stable SEI layer, which facilitates the subsequent rapid ion insertion and extraction. Meanwhile, -OH can form intermolecular hydrogen bonds with water molecules in the Zn²⁺ solvation sheath, reducing the strength of the solvation sheath to assist Zn²⁺ to be rapidly desolvated, effectively improving ion transport kinetics. At the same time, by reconstructing the electrolyte hydrogen bond network, hydrogen evolution reaction and zinc dendrite growth are further suppressed. Secondly, the photolyzed 2-methyl-5-nitroimidazole-1-ethanol additive can also disrupt the hydrogen bond network between water molecules in the electrolyte, resulting in a lower freezing point and maintaining high ionic conductivity even at low temperatures, thus significantly improving the low-temperature performance of the battery. The preparation process of this invention is simple and feasible. Only trace amounts of 2-methyl-5-nitroimidazole-1-ethanol are added to the base electrolyte at a set concentration. After complete dissolution, the mixture is fully exposed to natural light before direct battery assembly. Furthermore, the raw materials used in this invention are inexpensive and meet the requirements for the degradation and reuse of residual wastewater from antibiotic pharmaceutical production. This reduces battery manufacturing costs while solving the environmental problem of difficult pharmaceutical wastewater treatment, achieving both environmental and economic benefits.

[0066] The following further describes specific embodiments and experimental verifications of the present invention.

[0067] Example 1: Preparation of photoelectrolysis electrolyte of 2 M ZnSO4 + 2.5 mM 2-methyl-5-nitroimidazole-1-ethanol.

[0068] The electrolyte additive is 2-methyl-5-nitroimidazole-1-ethanol. The electrolyte formulation includes 2-methyl-5-nitroimidazole-1-ethanol, a soluble zinc salt, and deionized water. The zinc salt is zinc sulfate (ZnSO4), and the solvent is deionized water. The preparation method is as follows:

[0069] (1) Weigh 6.458 g of ZnSO4 solid powder, add 20 mL of deionized water, and stir thoroughly until completely dissolved to obtain a 2M ZnSO4 solution.

[0070] (2) Weigh 0.0086 g of 2-methyl-5-nitroimidazole-1-ethanol solid powder and add it to the 2MZnSO4 solution obtained in (1). Stir thoroughly until completely mixed to obtain mixed solution sample 1.

[0071] (3) Expose the mixed solution sample 1 obtained in (2) to natural light for 10 days or more to obtain the electrolyte sample of Example 1.

[0072] Example 2: Preparation of 2 M ZnSO4 + 5 mM 2-methyl-5-nitroimidazole-1-ethanol photoelectrolysis electrolyte.

[0073] The electrolyte additive is 2-methyl-5-nitroimidazole-1-ethanol. The electrolyte formulation includes 2-methyl-5-nitroimidazole-1-ethanol, a soluble zinc salt, and deionized water. The zinc salt is zinc sulfate (ZnSO4), and the solvent is deionized water. The preparation method is as follows:

[0074] (1) Weigh 6.458 g of ZnSO4 solid powder, add 20 mL of deionized water, and stir thoroughly until completely dissolved to obtain a 2M ZnSO4 solution.

[0075] (2) Weigh 0.0171g of 2-methyl-5-nitroimidazole-1-ethanol solid powder and add it to the 2MZnSO4 solution obtained in (1). Stir thoroughly until completely mixed to obtain mixed solution sample 2.

[0076] (3) Expose the mixed solution sample 2 obtained in (2) to natural light for 10 days or more to obtain the electrolyte sample of Example 2.

[0077] Example 3: Preparation of a photoelectrolysis electrolyte of 2 M ZnSO4 + 10 mM 2-methyl-5-nitroimidazole-1-ethanol

[0078] The electrolyte additive is 2-methyl-5-nitroimidazole-1-ethanol. The electrolyte formulation includes 2-methyl-5-nitroimidazole-1-ethanol, a soluble zinc salt, and deionized water. The zinc salt is zinc sulfate (ZnSO4), and the solvent is deionized water. The preparation method is as follows:

[0079] (1) Weigh 6.458 g of ZnSO4 solid powder, add 20 mL of deionized water, and stir thoroughly until completely dissolved to obtain a 2M ZnSO4 solution.

[0080] (2) Weigh 0.0342g of 2-methyl-5-nitroimidazole-1-ethanol solid powder and add it to the 2MZnSO4 solution obtained in (1). Stir thoroughly until completely mixed to obtain mixed solution sample 3.

[0081] (3) Expose the mixed solution sample 3 obtained in (2) to natural light for 10 days or more to obtain the electrolyte sample of Example 3.

[0082] Preparation of Comparative Example 1:2 M ZnSO4 Electrolyte

[0083] The electrolyte formulation includes a soluble zinc salt and deionized water. The zinc salt is zinc sulfate (ZnSO4), and the solvent is deionized water. Its preparation method is as follows:

[0084] Weigh 6.458 g of ZnSO4 solid powder, add 20 mL of deionized water, and stir thoroughly until completely dissolved to obtain the electrolyte sample of Comparative Example 1.

[0085] The above electrolyte was applied to an aqueous zinc battery, and characterization and electrochemical testing were performed. The results are illustrated below with reference to the accompanying figures:

[0086] (1) The contact angles of the electrolytes in Examples 1-3 and Comparative Example 1 were measured, and the measurement results are as follows: Figure 1 As shown. Figure 1 In Comparative Example 1 (a), the electrolyte contact angle is 89°, while... Figure 1 In (b)-(d), the contact angles of the electrolytes in Examples 1-3 were 81°, 34°, and 72°, respectively, indicating that all concentrations of the 2-methyl-5-nitroimidazole-1-ethanol additive, after photolysis, reduced the contact angle between the electrolyte and the zinc anode, improving the wettability of the electrolyte on the zinc anode surface and facilitating rapid ion transport. Simultaneously, the electrolyte wettability showed a trend of first decreasing and then increasing with increasing additive concentration, indicating that the electrolyte in Example 2 could maximize the diffusion and deintercalation of zinc ions on the anode surface.

[0087] (2) The electrolytes of Example 2 and Comparative Example 1 were subjected to Zn / / Zn symmetric battery assembly and constant current charge-discharge test.

[0088] Preparation of two electrode sheets: A zinc foil with a thickness of 100 μm is cut into circular sheets with a diameter of 12 mm. The circular sheets are then immersed in anhydrous ethanol for ultrasonic cleaning and dried to prepare them as electrode sheets for later use.

[0089] Battery fabrication: A commercial CR2032 electrode shell was used, and the separator was made of glass fiber (16 mm in diameter). 80 mL of electrolyte was added, and the battery was assembled in the following order: positive electrode shell, zinc electrode, separator, electrolyte, zinc electrode, gasket, and spring sheet. The battery was then pressurized and sealed to obtain a Zn / / Zn symmetric battery.

[0090] 1. Low-current constant-current charge-discharge test: After a suitable period of rest, the assembled battery is charged at 25°C at 1 mA cm⁻¹. -2 0.5mAh cm -2 A constant current charge-discharge test was performed under the specified current conditions. For example... Figure 2 As shown, Example 2 can cycle stably for more than 5400 hours under this current, while Comparative Example 1 can only cycle for less than 550 hours before short-circuiting. This indicates that the addition of 2-methyl-5-nitroimidazole-1-ethanol to the electrolyte after photolysis can improve the cycle life of the battery under low current.

[0091] 2. High-current constant-current charge-discharge test: After a suitable period of rest, the assembled battery is charged at 25°C and 20 mA cm⁻¹. -2 5mAh cm -2 A constant current charge-discharge test was performed under the specified current conditions. For example... Figure 3 As shown, Example 2 can cycle stably for more than 2000 hours under this current, while Comparative Example 1 can only cycle for less than 230 hours before short-circuiting. This indicates that the addition of 2-methyl-5-nitroimidazole-1-ethanol to the electrolyte after photolysis can improve the cycle life of the battery under high current.

[0092] (3) Assembly and testing of Zn / / Cu asymmetric cells using the electrolytes of Example 2 and Comparative Example 1.

[0093] Preparation of positive electrode: Cut copper foil with a thickness of 100 μm into circular pieces with a diameter of 12 mm, pour the circular pieces into anhydrous ethanol for ultrasonic cleaning, and dry them to use as positive electrode.

[0094] Negative electrode preparation: 100 μm thick zinc foil is cut into 12 mm diameter discs. The discs are then immersed in anhydrous ethanol for ultrasonic cleaning and dried to serve as negative electrode sheets.

[0095] Battery fabrication: A commercial CR2032 electrode shell was used, and the separator was made of glass fiber (16 mm in diameter). 80 μL of electrolyte was added dropwise. The battery was assembled in the following order: positive electrode shell, copper electrode, separator, electrolyte, zinc electrode, gasket, and spring sheet. The battery was then pressurized and sealed to obtain a Zn / / Cu asymmetric battery.

[0096] Zn / / Cu battery charge / discharge test: After a suitable period of rest, the assembled battery was charged and discharged at 25°C and 1 mA cm⁻¹. -2 1mAh cm -2 The charge-discharge test was conducted under the specified current conditions, with a charging cutoff voltage of 0.5V. For example... Figure 4 As shown, the electrolyte in Example 2, after photolysis with the addition of the 2-methyl-5-nitroimidazole-1-ethanol additive, exhibited a longer stable cycle period compared to Comparative Example 1. The battery in Example 2 achieved an average coulombic efficiency (CE) exceeding 99.8% after 1600 cycles. In contrast, the battery in Comparative Example 1, with an electrolyte concentration of less than 400 cycles, consistently exhibited sharp overcharging, indicating an internal short circuit that prevented the voltage from reaching the set value.

[0097] (4) In-situ optical microscopy tests of the Zn coating in Example 2 and Comparative Example 1:

[0098] Depend on Figure 5 It can be seen that using the electrolytes of Example 2 and Comparative Example 1 at 20 mA cm⁻¹ -2The discharge process at the Zn electrode interface was observed using an optical microscope under current conditions, with a scale bar of 120 μm. In Example 2, during the first 0-5 minutes of discharge, the zinc anode interface showed no significant smoothing or dendrite growth inhibition compared to Comparative Example 1. At 10 minutes of discharge, irregular crystals appeared at the zinc electrode interface of Comparative Example 1, while the zinc anode interface of Example 2 exhibited relatively higher smoothness. At 20 minutes of discharge, irregular crystals continued to grow at the zinc electrode interface of Comparative Example 1, while no obvious sharp dendrites appeared at the zinc anode interface of Example 2. At 30 minutes of discharge, a large number of irregular crystals appeared at the zinc electrode interface of Comparative Example 1, with the maximum dendrite height exceeding 320 μm. At this point, the zinc anode interface of Example 2 showed no significant change compared to 20 minutes of discharge, and no obvious sharp dendrites were generated. This indicates that the addition of 2-methyl-5-nitroimidazole-1-ethanol to the electrolyte photolysis can rapidly promote the formation of the SEI layer on the anode under high current conditions, while simultaneously inhibiting the large-scale accumulation of insulating byproducts and uncontrolled dendrite growth caused by the hydrogen evolution reaction.

[0099] (5) The Zn / / NaV3O8 full cell assembly and constant current charge-discharge test were performed on the electrolytes of Example 2 and Comparative Example 1.

[0100] Preparation of the positive electrode: The active material (NaV3O8·1.5H2O), binder (PVDF), and conductive agent (conductive carbon powder) were added to a mortar and mixed thoroughly. NMP solution was then added to the mortar and mixed until the slurry was smooth and fine. This slurry was poured onto the surface of a current collector (Ti foil). A 25 μm thick scraper was used to smooth the slurry on the Ti foil surface. The slurry was then dried in a 60℃ oven for 12 hours. Finally, the slurry was stamped into 12 mm diameter discs using an electrode stamping machine, with an active material loading of 1.7~2.2 mg / cm³. -2 It is intended to be used as a positive electrode sheet.

[0101] Negative electrode preparation: 100 μm thick zinc foil is cut into 12 mm diameter discs. The discs are then immersed in anhydrous ethanol for ultrasonic cleaning and dried to serve as negative electrode sheets.

[0102] Battery fabrication: A commercial CR2032 electrode shell was used, and the separator was made of glass fiber (16 mm in diameter). 80 μL of electrolyte was added dropwise. The battery was assembled in the following order: positive electrode shell, positive electrode plate, separator, electrolyte, negative electrode plate, gasket, and spring sheet. The battery was then pressurized and sealed to obtain a Zn / / NaV3O8 full cell.

[0103] 1.25℃ constant current charge-discharge test at room temperature: After standing for an appropriate time, the assembled battery was charged at 25℃ for 2 Ag. -1 Constant current charge-discharge tests were performed under current conditions, with a voltage range of 0.2~1.6 V. For example... Figure 6As shown, the initial discharge specific capacities of the batteries in Example 2 and Comparative Example 1 at this current are 135.8 and 112.9 mAhg, respectively. -1 After 1000 long cycles, the remaining capacities were 125.5 and 79.4 mAh g, respectively. -1 The capacity retention rates were 92.4% and 70.3%, respectively. This indicates that the electrolyte with added 2-methyl-5-nitroimidazole-1-ethanol, after photolysis, can not only improve the battery cycle capacity by participating in the solvation sheath, but also stabilize the battery's long-cycle performance by constructing an efficient SEI layer and accelerating ion transport kinetics.

[0104] 2. -10℃ Low-Temperature Constant Current Charge-Discharge Test: After a suitable period of rest, the assembled battery is charged at -10℃ using 1 Ag... -1 Constant current charge-discharge tests were performed under current conditions, with a voltage range of 0.2~1.6 V. For example... Figure 7 As shown, the initial discharge specific capacities of the batteries in Example 2 and Comparative Example 1 at this current are 86.7 and 5.1 mAh g, respectively. -1 After 2000 long cycles, the remaining capacity of the battery in Example 2 was 85.5 mAhg. -1 The capacity retention rate was 98.6%, and Example 2 exhibited relatively stable coulombic efficiency throughout the entire cycle, with an average coulombic efficiency as high as 99.3% after 2000 cycles. In contrast, the comparative example 1 battery showed abnormal fluctuations in coulombic efficiency throughout the cycle, and its discharge capacity approached zero. This was due to the large-scale condensation of Zn in the electrolyte of the comparative example 1 at this temperature. 2+ Normal transmission could not be achieved, and the voltage could not be charged to the specified value. This indicates that the freezing point of the electrolyte with added 2-methyl-5-nitroimidazole-1-ethanol was significantly lower than that of the control sample after photolysis, and its battery can ensure stable cycling for a long time at -10℃.

[0105] This invention employs photo-induced degradation of the pharmaceutical additive 2-methyl-5-nitroimidazole-1-ethanol in a basic aqueous electrolyte environment, thereby improving the electrolyte's ionic conductivity and expanding its electrochemical window. Simultaneously, it promotes rapid zinc ion migration, inhibits hydrogen evolution side reactions, and participates in the construction of a stable solid electrolyte interface (SEI), significantly enhancing the battery's cycle performance and coulombic efficiency. At low temperatures, the components obtained from the photodegradation of 2-methyl-5-nitroimidazole-1-ethanol have a regulatory effect on the hydrogen bond network of water molecules, maintaining good ionic conductivity and interfacial stability. By using the recalcitrant pharmaceutical component 2-methyl-5-nitroimidazole-1-ethanol as an additive and employing a simple and readily available photodegradation method, the residual aqueous solution of the pharmaceutical product can be recycled and reused as an electrolyte in an aqueous zinc battery. This optimizes zinc battery performance while achieving efficient treatment of industrial pollution and large-scale, high-efficiency zinc battery production.

[0106] In summary, the method for preparing zinc battery electrolytes using the photodegradable antibiotic additive of this invention can produce aqueous zinc batteries with better electrochemical performance and low-temperature adaptability. It can reduce the efficient and stable operating temperature range of aqueous zinc batteries to -10°C, and significantly improve the discharge capacity and cycle life of zinc batteries, thus improving overall battery performance and expanding their application scenarios. Furthermore, this invention demonstrates that a regenerated and environmentally friendly electrolyte highly compatible with zinc batteries can be prepared by simple treatment, including photodegradation, using 2-methyl-5-nitroimidazole-1-ethanol (obtainable from aqueous solutions of pharmaceutical residues). This has extremely high value in promoting the large-scale production and application of aqueous zinc batteries, achieving efficient treatment of industrial pollution and large-scale, high-efficiency zinc battery production while optimizing zinc battery performance, which is of great significance for improving the performance and production application of aqueous zinc batteries.

[0107] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. An aqueous zinc battery electrolyte, characterized in that, The zinc battery base electrolyte and 2-methyl-5-nitroimidazole-1-ethanol, the concentration of which is 2.5 mM to 10 mM, wherein the 2-methyl-5-nitroimidazole-1-ethanol is directed to crack the heterocycle of 2-methyl-5-nitroimidazole-1-ethanol and retain the nitro (-NO2) and hydroxyl (-OH) functional groups through photolysis treatment, the photolysis treatment is natural light photolysis treatment for more than 10 days, or the photolysis treatment uses a xenon lamp with similar spectral characteristics of natural light for irradiation, or the photolysis treatment uses a composite light source composed of a low-power ultraviolet lamp and a visible LED lamp for irradiation.

2. The aqueous zinc battery electrolyte of claim 1, wherein, The base electrolyte comprises ZnSO4 and deionized water.

3. The aqueous zinc battery electrolyte of claim 2, wherein, The concentration of ZnSO4 is 2 M.

4. A method of preparing the aqueous zinc battery electrolyte according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: 2-methyl-5-nitroimidazole-1-ethanol is added to the zinc battery base electrolyte to dissolve and obtain a mixed solution, the concentration of the 2-methyl-5-nitroimidazole-1-ethanol being 2.5 mM to 10 mM; The mixed solution is subjected to photolysis treatment to direct the heterocycle of 2-methyl-5-nitroimidazole-1-ethanol to crack and retain the nitro (-NO2) and hydroxyl (-OH) functional groups, thereby obtaining an aqueous zinc battery electrolyte after photolysis; the photolysis treatment is natural light photolysis treatment for more than 10 days, or the photolysis treatment uses a xenon lamp with similar spectral characteristics of natural light for irradiation, or the photolysis treatment uses a composite light source composed of a low-power ultraviolet lamp and a visible LED lamp for irradiation.

5. An aqueous zinc battery, characterized by, The positive electrode sheet, the negative electrode sheet, the separator, and the aqueous zinc battery electrolyte as claimed in any one of claims 1 to 3.

6. The aqueous zinc battery of claim 5, wherein, The positive electrode sheet comprises a vanadium-based positive electrode material.

7. The aqueous zinc battery of claim 6, wherein, The vanadium-based positive electrode material is NaV3O8·1.5H2O.

8. The aqueous zinc battery of any one of claims 5-7, wherein, The negative electrode sheet is a zinc foil.

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