Preparation method of aqueous zinc ion battery negative electrode, battery negative electrode and battery

Abstract

The invention discloses a preparation method of an aqueous zinc ion battery negative electrode, a battery negative electrode and a battery, and the preparation method comprises the following steps: S1, dissolving lipoic acid and copper chloride in ethanol according to a certain proportion, stirring and dissolving to obtain a mixed solution; s2, dropwise adding the mixed solution on the surface of the ground and polished zinc foil, and carrying out modification reaction at room temperature; and S3, taking out the modified zinc foil, and then drying the modified zinc foil in a vacuum drying oven to obtain the zinc metal negative electrode with the surface modified by the copper polylipoate. Through coordination of lipoic acid and copper chloride in an ethanol solution, a layer of uniform and stable polylipoic acid copper protective film is formed on the surface of the zinc metal negative electrode through polymerization. Copper ions in the copper chloride can be complexed and coordinated with lipoic acid, so that a stable and compact copper polylipoate protective film is generated on the surface of the zinc metal negative electrode; the protective film can effectively inhibit the growth of zinc dendrites, prevents the zinc dendrites from puncturing the diaphragm to cause short circuit of the battery, and improves the safety of the battery; and the formed protective film can effectively inhibit the generation of hydrogen evolution side reaction, reduce the loss of active substances, and improve the coulombic efficiency, cycling stability and capacity of the battery. The modification method disclosed by the invention is simple to operate, free of complex equipment and process, low in cost and easy to realize large-scale production, and has a good application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy batteries, and in particular relates to a method for preparing a negative electrode of an aqueous zinc ion battery, a battery negative electrode and a battery. Background Art

[0002] To address the greenhouse effect and air pollution caused by fossil fuels and achieve the "dual carbon" goals, there is an urgent need to develop advanced energy storage technologies and effectively utilize renewable energy. However, renewable energy is intermittent and its output power fluctuates, leading to grid frequency fluctuations and voltage instability. Introducing energy storage devices to implement peak-load shifting and valley-loading can alleviate the instability of power systems caused by renewable energy. Among various energy storage technologies, electrochemical energy storage is relatively well developed, with rechargeable batteries widely used in daily life. Over the past 30 years, lithium-ion batteries (LIBs) have been widely used in electric vehicles and portable electronics due to their high energy density and long cycle life. However, the nickel, cobalt, and fluorine used in LIBs can cause pollution and are difficult to recycle, and the organic electrolyte poses a flammable safety risk. Furthermore, the high cost of raw materials has limited their large-scale application in smart grids. Aqueous zinc-ion batteries (ZIBs) offer high theoretical capacity, low redox potential, low cost, low toxicity, and excellent safety, and they also have the potential to achieve higher energy density. These properties make ZIBs an attractive alternative to LIBs for energy storage, with broad application prospects in electric vehicles, drones, and energy storage cabinets.

[0003] However, ZIBs face many challenges in practical applications, such as dendrite growth, side reactions, instability and dissolution of positive electrode materials, resulting in low capacity and poor cycle stability. On the zinc metal negative electrode side, dendrite growth and related side reaction problems are particularly serious, which poses a major challenge to the performance and safety of the battery. During the charge and discharge process, zinc ions are unevenly deposited on the negative electrode surface, leading to the formation and gradual growth of dendrites. These dendrites can penetrate the diaphragm and cause internal short circuits, significantly reducing the cycle life and safety of the battery. In addition, side reactions between zinc metal and the electrolyte, including hydrogen evolution reaction and corrosion, not only consume metallic zinc and electrolyte, but also produce hydrogen, which leads to increased internal pressure, accelerates performance degradation and affects the operational reliability of the battery.

[0004] Currently, there are various methods for modifying zinc metal anodes, such as constructing artificial solid electrolyte interface membranes and optimizing electrolyte composition. However, these methods still have some shortcomings in practical applications. Therefore, developing a simple, efficient, and low-cost method for modifying the surface of zinc metal anodes is of great significance for improving the overall performance of aqueous zinc-ion batteries. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for preparing an aqueous zinc ion battery negative electrode, a battery negative electrode, and a battery, thereby solving the problems of dendrites and side reactions on the surface of the zinc metal negative electrode in aqueous zinc ion batteries. In particular, a method for surface modification of the zinc metal negative electrode of an aqueous zinc ion battery based on a thioctic acid-copper chloride ethanol solution is provided. This method forms a uniform and stable polythioic acid copper protective layer (poly(TA-Cu)) on the surface of the zinc metal negative electrode, inhibiting side reactions such as zinc dendrite growth and hydrogen evolution, thereby improving the cycle stability of the zinc metal negative electrode and the overall performance of the battery. The method is simple to operate, the modified layer is easily controllable, the design is strong, and the cost-effectiveness is good.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] In a first aspect, the present invention provides a method for preparing a negative electrode for an aqueous zinc ion battery, comprising the following steps:

[0008] S1, dissolving lipoic acid and copper chloride in ethanol in a certain proportion, stirring to dissolve, to obtain a mixed solution;

[0009] S2, adding the mixed solution dropwise onto the polished surface of the zinc foil to carry out a modification reaction at room temperature;

[0010] S3. Take out the modified zinc foil and then dry it in a vacuum drying oven to obtain a zinc metal negative electrode whose surface is modified by copper polylipoate.

[0011] In a preferred embodiment, in step S1, the concentration of lipoic acid is 0.1-1.0 mol / L, and the concentration of copper chloride is 0.01-0.1 mol / L.

[0012] In a preferred embodiment, in step S1, the stirring temperature is room temperature, and the stirring time is 10-60 minutes.

[0013] In a preferred embodiment, in step S2, the modification reaction time is 1-10 minutes.

[0014] In a preferred embodiment, in step S2, the mixed solution is added dropwise onto the polished surface of the zinc foil by drop coating, spin coating or spray coating.

[0015] In a preferred embodiment, in step S3, the drying temperature is 30-50°C, and the drying time is 2-6 hours.

[0016] In a second aspect, the present invention also provides an aqueous zinc ion battery negative electrode prepared using the preparation method described above.

[0017] In a third aspect, the present invention further provides an aqueous zinc ion battery comprising the aqueous zinc ion battery negative electrode as described above.

[0018] In a preferred embodiment, the positive electrode of the battery is a V2O5-PEDOT electrode sheet, the separator is glass fiber, and the electrolyte is a 2M ZnSO4 solution.

[0019] After adopting the above technical solution, the preparation method of the aqueous zinc ion battery negative electrode, the battery negative electrode and the battery provided by the present invention have the following beneficial effects compared with the prior art:

[0020] The present invention forms a uniform and stable protective film on the surface of a zinc metal negative electrode through the coordination of thioctic acid and copper chloride in an ethanol solution. The copper ions in the copper chloride can form a complex coordination with thioctic acid to form polythioate copper, thereby enhancing the stability and density of the protective film. The protective film can effectively inhibit the growth of zinc dendrites, preventing zinc dendrites from piercing the diaphragm and causing a battery short circuit, thereby improving battery safety. The formed protective film can also effectively inhibit the occurrence of hydrogen evolution side reactions, reduce the loss of active substances, and improve the coulombic efficiency, cycle stability, and capacity of the battery. The modification method of the present invention is simple to operate, does not require complex equipment and processes, is low in cost, is easy to implement on a large scale, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an undue limitation of the present invention. Obviously, the drawings described below are only some embodiments. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without inventive effort. In the accompanying drawings:

[0022] Figure 1 This is a comparison chart of the Coulombic efficiency curves of Zn / / Cu and Zn / / Cu@poly(TA-Cu) assembled in Example 1 of the present invention.

[0023] Figure 2 This is a comparison chart of the Coulombic efficiency curves of Zn / / Cu and Zn / / Cu@poly(TA-Cu) assembled in Example 2 of the present invention.

[0024] Figure 3This is a comparison of the Coulombic efficiency curves of Zn / / Cu and Zn / / Cu@poly(TA-Cu) assembled in Example 3 of the present invention.

[0025] Figure 4 This is an SEM image of the surface of the zinc metal negative electrode modified with poly(TA-Cu) in Example 3 of the present invention.

[0026] Figure 5 These are the SEM images and EDS images of the surface of the zinc metal negative electrode modified with poly(TA-Cu) in Example 3 of the present invention.

[0027] Figure 6 This is the Raman spectrum of the surface of the bare Zn and Zn@poly(TA-Cu) electrode sheets in Example 3 of the present invention.

[0028] Figure 7 FT-IR spectra of the surfaces of bare Zn and Zn@poly(TA-Cu) electrode sheets in Example 3 of the present invention.

[0029] Figure 8 This is a comparison chart of the long cycle performance of Zn / / Zn and Zn@poly(TA-Cu) / / Zn@poly(TA-Cu) symmetrical batteries assembled with Zn@poly(TA-Cu) and bare zinc electrode sheets in Example 3 of the present invention.

[0030] Figure 9 Comparison of the rate curves of Zn / / Zn and Zn@poly(TA-Cu) / / Zn@poly(TA-Cu) symmetrical cells assembled with Zn@poly(TA-Cu) and bare zinc electrode sheets in Example 3 of the present invention

[0031] Figure 10 This is a performance comparison chart of Zn / / V2O5-PEDOT and Zn@poly(TA-Cu) / / V2O5-PEDOT full batteries assembled with Zn@poly(TA-Cu) and bare zinc electrode sheets in Example 3 of the present invention.

[0032] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0034] The present invention adopts the method of fully mixing yellow lipoic acid powder (TA) and CuCl2 powder in anhydrous ethanol to obtain a mixed solution, then coating the solution on the surface of zinc foil by drop coating, spin coating or spraying, and vacuum drying to obtain a zinc metal negative electrode (Zn@poly(TA-Cu)) after the interface of lipoic acid and CuCl2 is modified.

[0035] The lipoic acid molecule contains two sulfhydryl groups, which can complex with metal ions. In aqueous zinc ion batteries, it complexes with zinc ions or other metal ions. In the present invention, through the coordination of lipoic acid and copper ions in copper sulfide, a polymer film with special properties is formed on the surface of the zinc metal negative electrode. This film can serve as a protective layer, can provide a uniform electric field and zinc ion flux field, guide zinc ions to deposit uniformly on the electrode surface, avoid excessive zinc ion deposition in local areas, thereby suppressing the formation of dendrites. In addition, it can avoid direct contact between the zinc metal negative electrode and the electrolyte, thereby suppressing side reactions such as corrosion and hydrogen evolution.

[0036] The Zn@poly(TA-Cu) negative electrode prepared by the present invention can achieve the purpose of slowing down dendrite growth and side reactions under the combined action of lipoic acid and CuCl2 on the zinc metal negative electrode, thereby greatly improving the cycle life and capacity of the battery. It has the advantages of simple preparation, easy control, high stability and large-scale preparation.

[0037] Furthermore, the positive electrode of the battery prepared by the present invention adopts a V2O5-PEDOT electrode sheet, the separator adopts glass fiber, and the electrolyte adopts a 2M ZnSO4 solution.

[0038] Specifically, the preparation method of the V2O5-PEDOT electrode sheet is as follows:

[0039] 1 g of commercial vanadium pentoxide (V2O5) was weighed using an electronic balance and added to 10 mL of deionized water. The mixture was allowed to stand for 10 min, and then 0.5 mL of EDOT was added thereto and stirred for 7 d.

[0040] The slurry was taken out, and the slurry was repeatedly filtered and washed three times in batches with deionized water. Then, it was placed in a vacuum freeze dryer and vacuum-frozen at -60°C for 24 hours to obtain green powder V2O5-PEDOT coated with PEDOT.

[0041] Weigh V2O5-PEDOT:C:PVDF=8:1:1, put it into a mortar, dilute it with NMP, and grind it manually for 1 hour to obtain a positive electrode slurry.

[0042] The slurry was coated on a stainless steel mesh with a diameter of 10 mm to ensure that the active material loading was 1-2 mg cm -2After coating, it was placed in a vacuum drying oven and vacuum dried at 100°C for 12 h to obtain a V2O5-PEDOT electrode sheet, which was sealed for later use.

[0043] It should be noted that the present invention uses a surface modification method to modify the surface of the zinc metal negative electrode of the zinc ion battery. Zinc metal or zinc alloy can be used as the negative electrode of the zinc ion battery. Its basic method is consistent with the preparation method of the aqueous zinc ion battery negative electrode provided by the present invention.

[0044] [Example 1]

[0045] This embodiment provides a method for preparing a negative electrode for an aqueous zinc ion battery, a negative electrode for the battery, and a battery. The method comprises:

[0046] 1. Prepare a mixed solution: dissolve 0.1 mol of lipoic acid and 0.01 mol of copper chloride in 1 L of ethanol, and stir at room temperature for 30 minutes to obtain a mixed solution with a lipoic acid concentration of 0.1 mol / L and a copper chloride concentration of 0.01 mol / L.

[0047] 2. Surface modification: add 60 μL of the above mixed solution onto the surface of the zinc foil using a pipette and react at room temperature for 5 minutes.

[0048] 3. Drying: Take out the modified zinc metal negative electrode and dry it in a vacuum drying oven at 40° C. for 4 hours to obtain a surface-modified zinc metal negative electrode.

[0049] Using poly(TA-Cu) to modify Cu foil, Zn / / Cu and Zn / / Cu@poly(TA-Cu) batteries were assembled and Coulombic efficiency was tested. -2 ,0.5mAh cm -2 Under the same conditions, it can stably cycle for 120 cycles, and its cycle stability is better than that of bare zinc electrode ( Figure 1 ).

[0050] [Example 2]

[0051] This embodiment provides a method for preparing a negative electrode for an aqueous zinc ion battery, a negative electrode for the battery, and a battery. The method comprises:

[0052] 1. Prepare a mixed solution: dissolve 0.5 mol of lipoic acid and 0.05 mol of copper chloride in 1 L of ethanol, and stir at room temperature for 30 minutes to obtain a mixed solution with a lipoic acid concentration of 0.5 mol / L and a copper chloride concentration of 0.05 mol / L.

[0053] 2. Surface modification: add 60 μL of the above mixed solution onto the surface of the zinc foil using a pipette and react at room temperature for 5 minutes.

[0054] 3. Drying: Place the modified zinc metal negative electrode in a vacuum drying oven and dry it at 40° C. for 4 hours to obtain a surface-modified zinc metal negative electrode.

[0055] The Zn / / Cu and Zn / / Cu@poly(TA-Cu) batteries were assembled by modifying Cu foil with poly(TA-Cu) and the Zn / / Cu@poly(TA-Cu) batteries were tested at 0.5 mA cm -2 ,0.5mAh cm -2 Under the same conditions, it can stably cycle for 550 cycles, and its cycle stability is better than that of bare zinc electrode ( Figure 2 ).

[0056] [Example 3]

[0057] This embodiment provides a method for preparing a negative electrode for an aqueous zinc ion battery, a negative electrode for the battery, and a battery. The method comprises:

[0058] 1. Prepare a mixed solution: Dissolve 1.0 mol of lipoic acid and 0.1 mol of copper chloride in 1 L of ethanol and stir at room temperature for 30 minutes to obtain a mixed solution with a lipoic acid concentration of 1.0 mol / L and a copper chloride concentration of 0.1 mol / L. Dissolve 1.0 mol of lipoic acid in 1 L of ethanol and stir at room temperature for 30 minutes to obtain a lipoic acid monomer solution.

[0059] 2. Surface modification: add 60 μL of the above mixed solution onto the surface of the zinc foil using a pipette and react at room temperature for 5 minutes.

[0060] 3. Drying: Place the modified zinc metal negative electrode in a vacuum drying oven and dry it at 40° C. for 4 hours to obtain a surface-modified zinc metal negative electrode.

[0061] The Zn / / Cu and Zn / / Cu@poly(TA-Cu) batteries were assembled by modifying Cu foil with poly(TA-Cu) and the Zn / / Cu@poly(TA-Cu) batteries were tested at 0.5 mA cm -2 ,0.5mAh cm -2 Under the same conditions, it can stably cycle 1100 times, and its cycle stability is better than that of bare zinc electrode ( Figure 3 ).

[0062] [Comparative Example]

[0063] The aqueous zinc ion battery was assembled using unmodified zinc metal anode, and the -2 ,0.5mAhcm -2 The coulombic efficiency test was carried out under the same conditions. After 78 cycles, a short circuit occurred and the battery failed. Its cycle stability was poor. In addition, through other electrochemical performance tests, the electrochemical performance of the battery assembled with the bare Zn electrode was significantly lower than that of the modified zinc metal negative electrode in the embodiment of the present invention.

[0064] Figure 4 The SEM morphology of the Zn@poly(TA-Cu) electrode sheet at different magnifications shows that its surface is flat and smooth.

[0065] Figure 5 Figure 3 is the element distribution on the surface of the Zn@poly(TA-Cu) electrode sheet, from which the presence of Cu and S elements on the surface can be determined.

[0066] Figure 6 To conduct Raman test results on the surface of Zn@TA and Zn@poly(TA-Cu) electrodes, Figure 6 The Raman spectrum shows that the characteristic peak of the disulfide bond on the surface of the Zn@TA electrode splits and broadens after the addition of CuCl2, which confirms that lipoic acid is ring-opened and polymerized into polylipoic acid.

[0067] Figure 7 The FT-IR test results of Zn@TA and Zn@poly(TA-Cu) electrode surfaces are shown in the spectra. As can be seen from the spectra, for the lipoic acid monomer on the surface of Zn@TA electrode, 1686.04 cm -1 The strong absorption peak at 1724.17 cm-1 on the surface of the Zn@poly(TA-Cu) electrode is due to the stretching vibration peak of C=O, which may come from the carboxyl group in the lipoic acid monomer. In contrast, the absorption peak of C=O on the surface of the Zn@poly(TA-Cu) electrode moves to a higher position of 1724.17 cm-1. -1 position, this is because the carboxyl group is 2+ The coordination effect of Zn@poly(TA-Cu) enhances the stretching of C=O in the polythioate copper modified layer. Moreover, the FT-IR spectrum of Zn@poly(TA-Cu) electrode sheet shows a peak at 1583.97 cm -1 A new absorption peak appears at the position, which is Cu 2+ The asymmetric stretching vibration absorption peak of the carboxyl group after coordination further confirms that Cu 2+ It forms a strong complex with the carboxyl group.

[0068] Figure 8 For the Zn / / Zn and Zn@poly(TA-Cu) / / Zn@poly(TA-Cu) symmetric cells at 0.25 mA cm -2 ,0.25mAh cm -2 The constant current cyclic charge-discharge curves under the same conditions show that the Zn / / Zn symmetric battery short-circuited after only 200 hours of cycling. However, the Zn@poly(TA-Cu) / / Zn@poly(TA-Cu) symmetric battery can stably cycle for 1200 hours, showing better long-term cycling performance than the Zn / / Zn symmetric battery.

[0069] Figure 9 The rate performance of Zn / / Zn and Zn@poly(TA-Cu) / / Zn@poly(TA-Cu) symmetric batteries at different current densities and capacities is shown. The Zn@poly(TA-Cu) / / Zn@poly(TA-Cu) symmetric battery still has excellent cycling stability compared with the Zn / / Zn symmetric battery.

[0070] In order to verify the practical feasibility of Zn@poly(TA-Cu) electrode sheet, V2O5-PEDOT electrode sheet was used as the positive electrode to assemble Zn / / V2O5-PEDOT and Zn@poly(TA-Cu) / / V2O5-PEDOT full batteries in 4Ag -1 The long cycle test was carried out under the condition of 1000 cycles. It can be seen that after 800 cycles, the Zn@poly(TA-Cu) / / V2O5-PEDOT full battery still has a higher capacity ( Figure 10 ).

[0071] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations 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 one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0072] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with this patent can make slight changes or modifications to equivalent embodiments of equivalent changes using the above-mentioned technical contents without departing from the scope of the technical solution of the present invention. The implementation schemes in the above-mentioned embodiments can also be further combined or replaced. However, any simple modifications, equivalent changes and modifications made to the above-mentioned embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the solution of the present invention.

Claims

1. A method for preparing a negative electrode for an aqueous zinc ion battery, characterized in that: The following steps are involved: S1, dissolving lipoic acid and copper chloride in ethanol in a certain proportion, stirring to dissolve, to obtain a mixed solution; S2, adding the mixed solution dropwise onto the polished surface of the zinc foil to carry out a modification reaction at room temperature; S3. Take out the modified zinc foil and dry it in a vacuum drying oven to obtain a zinc metal negative electrode whose surface is modified by copper polylipoate.

2. The preparation method according to claim 1, wherein: In step S1, the concentration of lipoic acid is 0.1-1.0 mol / L, and the concentration of copper chloride is 0.01-0.1 mol / L.

3. The preparation method according to claim 1, wherein: In step S1, the stirring temperature is room temperature, and the stirring time is 10-60 minutes.

4. The preparation method according to claim 1, wherein: In step S2, the modification reaction time is 1-10 minutes.

5. The preparation method according to claim 1, wherein: In step S2, the mixed solution is added dropwise onto the polished surface of the zinc foil by drop coating, spin coating or spray coating.

6. The preparation method according to claim 1, wherein: In step S3, the drying temperature is 30-50° C., and the drying time is 2-6 hours.

7. An aqueous zinc ion battery, characterized in that: The invention comprises the aqueous zinc ion battery negative electrode according to any one of claims 1 to 6.

8. The aqueous zinc ion battery according to claim 7, wherein The positive electrode of the battery adopts a V2O5-PEDOT electrode sheet, the diaphragm adopts glass fiber, and the electrolyte adopts a 2M ZnSO4 solution.

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