Acidic aqueous zinc ion battery electrolyte and battery

Abstract

The invention belongs to the technical field of aqueous batteries, and particularly relates to an acidic aqueous zinc ion battery electrolyte and a battery. The acidic aqueous zinc ion battery electrolyte comprises zinc ions, acid radical ions and 4-nitrophenylethylamine hydrobromide. According to the acidic aqueous zinc ion battery electrolyte, 4-nitrophenylethylamine hydrobromide is used as a cathode active material, and a nitro group of the 4-nitrophenylethylamine hydrobromide is used as an electron accepting center, so that a multi-electron transfer reaction is promoted; the protonated ethylamine partially improves the water solubility, and inhibits molecular aggregation and stabilizes the reduction state (-NHOH) through electrostatic repulsion. Experimental results show that under different hydrochloric acid concentrations (0.3 M to 1M), the coulombic efficiency of the battery under the current density of 20mA / cm < 2 > is maintained at 100%, and the voltage efficiency is improved along with the increase of the hydrochloric acid concentration.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aqueous batteries, and particularly relates to an acidic aqueous zinc ion battery electrolyte and a battery. BACKGROUND

[0002] Aqueous zinc ion batteries have become one of the most potential energy storage technologies in large-scale energy storage systems, portable electronic devices and other fields due to their high safety, environmental friendliness and low raw material cost. Among them, the acidic electrolyte system plays an important role in the research and application of aqueous zinc ion batteries due to its high ionic conductivity and good zinc negative electrode electrochemical stability. The performance optimization of cathode materials, as the core component determining the energy density, cycle life and voltage efficiency of the battery, is a key breakthrough direction for the development of current acidic aqueous zinc ion battery technology.

[0003] However, the existing cathode materials of acidic aqueous zinc ion batteries still have many technical bottlenecks: first, traditional inorganic cathode materials such as manganese oxides and vanadium oxides have low solubility and unstable reduction state in acidic electrolyte, resulting in serious loss of active substances and significant reduction of cycle life; second, some complex organic cathode molecules have certain electrochemical activity, but their synthesis process is complicated, production cost is high, and environmental compatibility is poor; third, the existing cathode electrolyte is prone to irreversible side reactions (such as oxygen evolution reaction and material structure decomposition) in acidic medium, which further limits the improvement of battery energy density and the maintenance of cycle stability, and the insufficient voltage efficiency also restricts the practical application value of the battery.

[0004] The existence of the above problems seriously restricts the commercialization process of acidic aqueous zinc ion batteries, and there is currently no effective solution that can overcome these defects comprehensively. SUMMARY

[0005] The present application introduces 4-nitrophenethylamine hydrobromide (molecular formula: C8H 11 BrN2O2) as a new type of organic cathode active material for acidic aqueous zinc ion battery electrolyte and battery technology. Based on the existing mature pharmaceutical intermediate production scale, this compound has potential cost advantage; through molecular structure design, the nitro group can act as an electron accepting center to promote multi-electron transfer reaction, and the protonated ethylamine part can improve water solubility and inhibit molecular aggregation through electrostatic repulsion to stabilize the reduction state (-NHOH), thereby effectively solving the problems of low solubility, unstable reduction state and insufficient voltage efficiency of existing cathode materials, achieving higher energy density, more stable cycle performance and excellent safety.

[0006] In order to achieve the above purpose, the present application can adopt the following technical solutions: The acid aqueous zinc ion battery electrolyte provided by the application comprises zinc ions, acid radical ions and 4-nitrophenethylamine hydrobromide.

[0007] Preferably, in the acid aqueous zinc ion battery electrolyte, the concentration of 4-nitrophenethylamine hydrobromide is 0.05M-0.15M.

[0008] Preferably, in the acid aqueous zinc ion battery electrolyte, the pH of the acid aqueous zinc ion battery electrolyte is ≤0.5.

[0009] Preferably, in the acid aqueous zinc ion battery electrolyte, the zinc ions are from one or more of zinc chloride, zinc sulfate or zinc nitrate; and / or the acid radical ions are from one or more of hydrochloric acid, sulfuric acid or nitric acid.

[0010] More preferably, in the acid aqueous zinc ion battery electrolyte, the concentration of zinc ions is 0.4M-0.6M; and / or the concentration of acid radical ions is 0.3M-1M.

[0011] The acid aqueous zinc ion battery provided by the application comprises the acid aqueous zinc ion battery electrolyte, a positive electrode and a negative electrode.

[0012] Preferably, in the acid aqueous zinc ion battery, the negative electrode is a zinc sheet.

[0013] Preferably, in the acid aqueous zinc ion battery, the preparation method of the positive electrode comprises: coating a carbon plate on a pretreated graphite felt to obtain a positive electrode, wherein the pretreatment comprises: treating at 400℃-600℃ in an air atmosphere for 4h-6h.

[0014] The acid aqueous zinc ion battery electrolyte provided by the application uses 4-nitrophenethylamine hydrobromide as a cathode active material, the nitro group of which serves as an electron-accepting center, promoting multi-electron transfer reactions; the protonated ethylamine part improves water solubility and inhibits molecular aggregation and stabilizes the reduced state (-NHOH) through electrostatic repulsion. 2 The coulombic efficiency of the battery under a current density of 20mA / cm BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the structural formula of 4-nitrophenethylamine hydrobromide (C8H 11 BrN2O2); Figure 2 is the charge-discharge curve of the battery based on the electrolyte (0.3M HCL) prepared in Example 1; Figure 3The charge-discharge curves of the battery based on the electrolyte (0.5M HCl) prepared in Example 2 are shown. Figure 4 The charge-discharge curves of the battery based on the electrolyte (0.7M HCl) prepared in Example 3 are shown. Figure 5 The charge-discharge curves of the battery based on the electrolyte (1.0 M HCl) prepared in Example 4 are shown. Figure 6 Cyclic graphs of coulombic efficiency and voltage efficiency of batteries based on electrolytes prepared in Examples 1 to 4. Detailed Implementation

[0016] The embodiments described are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the embodiments described. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0017] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Singular expressions include plural expressions unless they have a distinct meaning in the context. As used herein, it should be understood that terms such as “comprising,” “having,” “including,” are intended to indicate the presence of features, numbers, operations, components, parts, elements, materials, or combinations thereof. The terminology of the invention is disclosed in the specification and is not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials, or combinations thereof may be present or added. As used herein, “ / ” may be interpreted as “and” or “or,” depending on the context.

[0018] In this invention, "M" is a known unit of concentration, which is mol / L.

[0019] In a first aspect, embodiments of the present invention provide an acidic aqueous zinc-ion battery electrolyte, comprising zinc ions, acid radical ions, and 4-nitrophenylethylamine hydrobromide.

[0020] It should be noted that the acidic aqueous zinc-ion battery electrolyte provided by this invention uses 4-nitrophenylethylamine hydrobromide as the cathode active material. Its nitro group acts as an electron acceptor center, promoting multi-electron transfer reactions. The protonated ethylamine portion enhances water solubility and inhibits molecular aggregation and stabilizes the reduced state (–NHOH) through electrostatic repulsion. Experimental results show that, under different hydrochloric acid concentrations (0.3M to 1M), the battery achieves a performance of 20 mA / cm². 2 The coulombic efficiency remained at 100% at the current density, while the voltage efficiency increased with increasing hydrochloric acid concentration. Additionally, 4-nitrophenylethylamine hydrobromide (C8H...) 11 The structural formula of BrN2O2 is as follows: Figure 1As shown.

[0021] In some specific examples, the concentration of 4-nitrophenylethylamine hydrobromide in the above-mentioned acidic aqueous zinc-ion battery electrolyte is 0.05M-0.15M.

[0022] It should be noted that the concentration of 4-nitrophenylethylamine hydrobromide in this invention is 0.05M-0.15M, such as 0.08M, 0.1M or 0.13M.

[0023] In some specific examples, the pH of the acidic aqueous zinc-ion battery electrolyte is ≤0.5.

[0024] In some specific examples, the zinc ions in the acidic aqueous zinc-ion battery electrolyte described above come from one or more of zinc chloride, zinc sulfate, or zinc nitrate.

[0025] It should be noted that the zinc ions in the electrolyte of the present invention come from any water-soluble zinc salt known in the art, including but not limited to the zinc salts listed above.

[0026] In some specific examples, the concentration of zinc ions in the above-mentioned acidic aqueous zinc-ion battery electrolyte is 0.4M-0.6M.

[0027] It should be noted that the concentration of zinc ions in this invention can be 0.4M-0.6M, such as 0.45M, 0.5M or 0.55M.

[0028] In some specific examples, the acid radicals in the above-mentioned acidic aqueous zinc-ion battery electrolytes come from one or more of hydrochloric acid, sulfuric acid, or nitric acid.

[0029] It should be noted that the anions in this invention are those known in the art, including but not limited to the anions listed above.

[0030] In some specific examples, the concentration of acid radical ions in the above-mentioned acidic aqueous zinc-ion battery electrolyte is 0.3M-1M.

[0031] It should be noted that the concentration of the anion can be between 0.3M and 1M, such as 0.4M, 0.5M, 0.6M, 0.7M, 0.8M, or 0.9M. Furthermore, by adjusting the anion concentration to a specified value, the high solubility of this compound, stemming from the hydrophilicity of the protonated amine group, ensures that the electrolyte pH is within the acidic range (pH < 2) to activate the nitro reduction mechanism. In addition, experimental results show that the battery maintains a solubility of 20 mA / cm² at different hydrochloric acid concentrations (0.3M to 1M). 2 The coulombic efficiency at current density remains at 100%, while the voltage efficiency increases with increasing hydrochloric acid concentration.

[0032] Secondly, embodiments of the present invention provide an acidic aqueous zinc-ion battery, which includes the above-mentioned acidic aqueous zinc-ion battery electrolyte, a positive electrode, and a negative electrode.

[0033] It should be noted that the acidic aqueous zinc-ion battery electrolyte of this invention can be used with positive and negative electrodes to prepare an acidic aqueous zinc-ion battery, and the preparation method is known in the art. Furthermore, the battery of this invention has high solubility and low cost potential, and achieves high capacity and high stability through the electrochemical reduction mechanism of nitro compounds, making it suitable for large-scale energy storage applications.

[0034] In some specific examples, the negative electrode in the aforementioned acidic aqueous zinc-ion battery is a zinc sheet.

[0035] It should be noted that the negative electrode in this invention is known in the art, and those listed above can be selected.

[0036] In some specific examples, the preparation method of the positive electrode in the above-mentioned acidic aqueous zinc-ion battery includes: pre-treating graphite felt and then coating it with a carbon plate to obtain the positive electrode, wherein the pre-treatment includes: treating it in an air atmosphere at 400℃-600℃ for 4h-6h.

[0037] It should be noted that the positive electrode in this invention is known in the art, and those in the art can choose the positive electrode listed above.

[0038] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below.

[0039] Preparation Examples Example 1 Mix 0.5M zinc chloride and 0.1M 4-nitrophenylethylamine hydrobromide (C8H) 11 The electrolyte is obtained by dissolving BrN2O2 in deionized water and adding 0.3M hydrochloric acid to adjust the pH to 0.5.

[0040] Example 2 Mix 0.5M zinc chloride and 0.1M 4-nitrophenylethylamine hydrobromide (C8H) 11 The electrolyte is obtained by dissolving BrN2O2 in deionized water and adding 0.5M hydrochloric acid to adjust the pH to 0.3.

[0041] Example 3 Mix 0.5M zinc chloride and 0.1M 4-nitrophenylethylamine hydrobromide (C8H) 11 The electrolyte is obtained by dissolving BrN2O2 in deionized water and adding 0.7M hydrochloric acid to adjust the pH to 0.15.

[0042] Example 4 Mix 0.5M zinc chloride and 0.1M 4-nitrophenylethylamine hydrobromide (C8H) 11 Dissolve BrN2O2 in deionized water and add 1M hydrochloric acid to adjust the pH to 0 to obtain the electrolyte.

[0043] Performance testing In the following tests, the battery assembly method is as follows: the negative and positive electrodes are inserted into the electrolyte to form an open-circuit battery; the battery is assembled at room temperature to obtain the battery; the specific details of the negative and positive electrodes are as follows: Negative electrode: Commercial zinc sheet with a thickness of 2.0 mm is used, and the oxide layer is removed by surface cleaning treatment to serve as the negative electrode; Positive electrode: Graphite felt (2cm×2cm) with a porosity of 94% is pretreated (heat pretreated in a muffle furnace at 500℃ for 5 hours) and then coated with carbon plate as the positive electrode.

[0044] In the following tests, constant current charge-discharge cycle tests were performed on a battery test system (BTS), with a current density of 20 mA / cm². 2 Charge to the upper limit voltage (based on nitro reduction potential) and discharge to the lower limit voltage; cycle at least 50 times, and monitor coulombic efficiency, voltage efficiency and capacity decay.

[0045] The charge-discharge performance of batteries based on the electrolytes prepared in Examples 1 to 4 was tested according to the above test method, and the charge-discharge curves are shown below. Figures 2 to 5 As shown, the results indicate that the operating voltage range is approximately 1.2 V (from 1.8 V to 0.6 V) (specifically, the discharge begins at approximately 1.8 V at the end of charging (vs. Ag / AgCl) and ends at approximately 0.6 V, indicating that the actual operating voltage of the battery ranges from a high point (~1.8 V) to a low point (~0.6 V). Therefore, the operating voltage range is approximately 1.2 V (calculated as: 1.8 V - 0.6 V = 1.2 V)). As the hydrochloric acid concentration increases from 0.3 M to 1.0 M, the discharge voltage increases from approximately 0.5 V to approximately 0.8 V, which will contribute to improved voltage efficiency.

[0046] In addition, the coulombic efficiency and voltage efficiency of the batteries based on the electrolytes prepared in Examples 1 to 4 are as follows: Figure 6 As shown in the figure (where the top spherical curve represents the coulombic efficiency, which is 100% for all HCl concentrations; the other geometric curves represent the voltage efficiency for different HCl concentrations), the results show: The battery based on the electrolyte prepared in Example 1 exhibited a coulombic efficiency of 100% and a voltage efficiency of 55% (based on the average charge-discharge voltage difference). At this concentration, nitro reduction primarily occurs via 2e⁻. —The process involves the accumulation of intermediates, leading to a slight overpotential. The coulombic efficiency and voltage efficiency of the battery based on the electrolyte prepared in Example 2 were 100% and 60%, respectively. The voltage efficiency of Example 2 was higher than that of Example 1, indicating that the increased protons promoted the dehydration step and accelerated the overall reaction. The coulombic efficiency and voltage efficiency of the battery based on the electrolyte prepared in Example 3 are 100% and 65%, respectively. The voltage efficiency of Example 3 is further improved compared with Example 1 and Example 2. The proton coupling electron transfer is optimized at this concentration, reducing energy loss. The coulombic efficiency and voltage efficiency of the battery based on the electrolyte prepared in Example 4 were 100% and 70%, respectively. The voltage efficiency of Example 4 was further improved compared with that of Examples 1, 2 and 3. The high acidity stabilized the reduced state and achieved performance close to the theoretical capacity.

[0047] In summary, the stability of the coulombic efficiency of batteries with electrolytes prepared with hydrochloric acid of different concentrations is attributed to the electrostatic protection of the reduced state, while the improvement in voltage efficiency is positively correlated with proton concentration. That is, as the hydrochloric acid concentration increases, the proton concentration increases, which promotes the cathode reaction kinetics and thus improves the voltage efficiency, while the coulombic efficiency remains unaffected, indicating that the system is highly reversible.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An acidic aqueous zinc-ion battery electrolyte, characterized in that, It includes zinc ions, acid radicals, and 4-nitrophenylethylamine hydrobromide.

2. The acidic aqueous zinc-ion battery electrolyte according to claim 1, characterized in that, The concentration of 4-nitrophenylethylamine hydrobromide is 0.05M-0.15M.

3. The acidic aqueous zinc-ion battery electrolyte according to claim 1, characterized in that, The pH of the acidic aqueous zinc-ion battery electrolyte is ≤0.

5.

4. The acidic aqueous zinc-ion battery electrolyte according to any one of claims 1 to 3, characterized in that, Zinc ions originate from one or more of zinc chloride, zinc sulfate, or zinc nitrate; and / or The anions come from one or more of hydrochloric acid, sulfuric acid, or nitric acid.

5. The acidic aqueous zinc-ion battery electrolyte according to claim 4, characterized in that, The concentration of zinc ions is 0.4M-0.6M; and / or The concentration of anions is 0.3M-1M.

6. An acidic aqueous zinc-ion battery, characterized in that, It includes the acidic aqueous zinc-ion battery electrolyte, positive electrode, and negative electrode as described in any one of claims 1 to 5.

7. The acidic aqueous zinc-ion battery according to claim 6, characterized in that, The negative electrode is a zinc sheet.

8. The acidic aqueous zinc-ion battery according to claim 6 or 7, characterized in that, The preparation method of the positive electrode includes: coating a carbon plate with a graphite felt after pretreatment to obtain the positive electrode, wherein the pretreatment includes: treating in an air atmosphere at 400℃-600℃ for 4h-6h.

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