Method for improving effectiveness of amino acid additive, zinc negative electrode and zinc ion battery

Abstract

The invention belongs to the field of zinc ion batteries, and discloses a method for improving the effectiveness of an amino acid additive, a zinc negative electrode and a zinc ion battery. The method comprises the following steps: mixing amino acid, lyophilic zinc salt and water, and stirring to obtain an electrolyte solution containing an amino acid additive; immersing bare zinc metal and standing in the electrolyte solution containing the amino acid additive; in the standing process, discontinuously stirring the electrolyte solution containing the amino acid additive on the upper layer; and after standing is finished, washing with water, and naturally airing to obtain the zinc negative electrode with an amino acid adsorption strengthening layer adsorbed on the surface. After the effectiveness of the amino acid additive is improved, rapid zinc ion transfer kinetics, uniform zinc deposition and a highly reversible zinc deposition / stripping process can be realized for the obtained zinc negative electrode, and parasitic reaction can be effectively inhibited.

Description

Technical Field

[0001] This invention belongs to the field of zinc-ion batteries, and more specifically, relates to a method for improving the effectiveness of amino acid additives, a zinc anode, and a zinc-ion battery. Background Technology

[0002] With the booming development of the new energy field, energy storage devices not only need to have long battery life, i.e., high energy density, but also sufficient safety. Safety has always been the most important concern in the energy storage field. Aqueous zinc-ion batteries have stood out among many energy storage devices due to their high energy density, high power density, low cost, green environmental protection, and extremely safe characteristics, becoming a current research hotspot.

[0003] As one of the most critical components of zinc-ion batteries, the zinc anode should possess good stability. However, in aqueous electrolytes, zinc anodes often face problems such as corrosion, interfacial hydrogen evolution, byproduct accumulation, and zinc dendrite formation, which significantly shorten their lifespan. To address these issues, various strategies have been proposed, including constructing artificial solid / electrolyte interfaces, designing zinc-loving coatings, modifying current collectors, adding electrolyte additives, and regulating the directional growth of zinc. Most of these existing strategies suffer from complex preparation processes, poor reproducibility, and high costs. Adding additives to the electrolyte is the simplest and most convenient way to commercially produce zinc ions. Among electrolyte additives, amino acid additives are widely used due to their environmental friendliness, low cost, and abundance of zinc-loving functional groups. These additives can preferentially adsorb onto the zinc anode surface to form an adsorption layer, providing some protection to the zinc anode, while simultaneously optimizing the solvation shell of zinc ions, promoting uniform zinc deposition, and improving the surface uniformity of the zinc anode. Although this strategy can significantly improve the electrochemical performance of zinc anodes, the current electrochemical performance of zinc anodes is still far from meeting the standards for commercially viable zinc-ion batteries.

[0004] As can be seen from the above strategies of using amino acid additives to regulate the zinc anode, the key to achieving the commercial standards of zinc-ion batteries in terms of electrochemical performance of the zinc anode lies in improving the effectiveness of amino acid regulation. However, there is currently no mechanism for improving the effectiveness of amino acid additives, thus breakthroughs in this field are urgently needed. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method to improve the effectiveness of amino acid additives, as well as a zinc anode and a zinc-ion battery. This invention, by improving the effectiveness of amino acid additives, enables the zinc anode obtained in this invention to achieve rapid zinc-ion transfer kinetics, uniform zinc deposition, a highly reversible zinc deposition / stripping process, and effective suppression of parasitic reactions.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for improving the effectiveness of amino acid additives, the method comprising the following steps: S1: Mix amino acids, hydrophilic zinc salts and water, stir, and obtain an electrolyte solution containing amino acid additives; S2: Immerse the bare zinc metal in the electrolyte solution containing the amino acid additive and let it stand; and during the standing process, stir the electrolyte solution containing the amino acid additive intermittently. S3: After step S2 has been completed, the zinc anode is rinsed with water and air-dried to obtain a zinc anode with an amino acid adsorption enhancement layer on its surface.

[0007] The technical principle of this invention is as follows: The inventors believe that the physicochemical properties of amino acids are related to electrolyte salts, particularly the anions in the electrolyte. Anions may enhance or weaken the effectiveness of amino acid additives through interactions with specific functional groups of amino acid molecules or solvents. Hypotonic anions can abstract water molecules surrounding amino acids, weakening the hydration structure of the amino acid molecule, which is beneficial to the affinity of amino acids on zinc surfaces. This is because zinc anodes have a better affinity for amino acids than for water. Therefore, this water-abstraction effect can improve the effectiveness of amino acids in regulating the anode interface, providing better control over the zinc anode.

[0008] This invention enhances the affinity of the amino acid adsorption layer on the zinc surface by using hydrophilic anions to capture water molecules surrounding amino acid molecules, thereby improving the effectiveness of the amino acid additive and obtaining a zinc anode with an amino acid adsorption enhancement layer on its surface (i.e., the optimized zinc anode). Figure 1 As shown, the zinc anode of this invention uses amino acids (such as methionine, which is a naturally occurring amino acid and therefore safe and environmentally friendly) as additives in the electrolyte, and hydrophilic anions (such as hydrophilic sulfate) as enhancers for the amino acid additives. Simultaneously, the hydrophilic zinc salt also serves as the electrolyte salt, and water is used as the solvent. Specifically: For zinc anodes: Since amino acid additives contain zinc-loving carboxyl and amino groups, they can spontaneously adsorb onto the zinc anode surface. The lyophilic anions in the electrolyte salt have strong hydration capabilities, which can attract water molecules surrounding amino acid molecules. This water-attracting effect enhances the affinity of the amino acid adsorption layer on the zinc surface. Because zinc anodes have a better affinity for amino acids than water, weakening the hydration structure of amino acid molecules can enhance the stability of the amino acid adsorption layer on the zinc surface, resulting in an optimized zinc anode (i.e., a zinc anode with a surface-enhanced amino acid adsorption layer).

[0009] According to the present invention, preferably, the content of amino acids is 0.8-1.1 wt%, the content of water is 55-70 wt%, and the content of hydrophilic zinc salt is 35-50 wt%, based on the total weight of the electrolyte solution containing amino acid additives.

[0010] According to the present invention, preferably, the amino acid is at least one selected from methionine, proline, and glycine.

[0011] According to the present invention, preferably, the hydrophilic zinc salt is at least one of zinc sulfate, zinc acetate and zinc dihydrogen phosphate.

[0012] According to the present invention, preferably, in step S1: the stirring time is 0.5-2 h, and the stirring speed is 200-500 r / min.

[0013] According to the present invention, preferably, in step S2: The settling time is 24-48 hours; The intermittent stirring is: during the settling process, the electrolyte solution containing amino acid additives is stirred once every 1-3 hours.

[0014] In this invention, the purpose of intermittently stirring the electrolyte solution containing amino acid additives on the upper layer of bare zinc metal is to allow the lyophilic anions in the lyophilic zinc salt to come into full contact with the amino acids, thus completing the process of enhancing the effectiveness of the amino acid additives.

[0015] According to the present invention, preferably, the bare zinc metal is in the form of a thin circular sheet with a thickness of 10-50 μm and a diameter of 1-1.2 cm; The volume of the electrolyte solution containing amino acid additives used in step S2 is 50-70 mL.

[0016] In this invention, the purpose of the water rinsing in step S3 is to remove excess electrolyte solution from the zinc negative electrode surface using deionized water. Preferably, the volume of deionized water used for rinsing is 50-100 mL, and the air-drying time is 6-10 h.

[0017] The second aspect of the present invention provides a zinc anode with an amino acid adsorption enhancement layer on its surface obtained by the method described above for improving the effectiveness of amino acid additives.

[0018] A third aspect of the present invention provides a zinc-ion battery, wherein the negative electrode of the zinc-ion battery is a zinc negative electrode with an amino acid adsorption reinforcement layer on its surface.

[0019] According to the present invention, preferably, the zinc-ion battery further includes an electrolyte; the electrolyte of the zinc-ion battery includes the following components: amino acids, water and a hydrophilic zinc salt, wherein the concentration of amino acids in the electrolyte is 0.05-0.15 mol / L, and the concentration of the hydrophilic zinc salt in the electrolyte is 1.5-2.5 mol / L.

[0020] According to the present invention, preferably, the zinc-ion battery has a button cell structure, and the zinc-ion battery further includes: a positive electrode, a separator, a stainless steel gasket, and a stainless steel battery casing. The pressure of the press used to seal the button cell structure is 1-3 MPa.

[0021] In this invention, as a preferred embodiment, the thickness of the stainless steel gasket is 400-600 μm.

[0022] In this invention, as a preferred embodiment, the positive electrode slurry of the positive electrode sheet, based on the total weight of the slurry, comprises: 5-15 wt% polyvinylidene fluoride, 15-25 wt% acetylene black, and 65-75 wt% vanadium dioxide; the current collector of the positive electrode sheet is at least one selected from titanium foil, stainless steel foil, and copper foil, and the current collector of the positive electrode sheet is in the form of a thin circular sheet with a thickness of 10 μm and a diameter of 1 cm; the preparation method of the positive electrode sheet includes: (1) The polyvinylidene fluoride, acetylene black, vanadium dioxide and solvent are mixed and stirred evenly to obtain a positive electrode slurry; (2) The positive electrode slurry is coated on the surface of the current collector, vacuum dried, and cut into sheets to obtain the positive electrode sheet.

[0023] In step (1): The stirring time is 0.5 h-8 h, and the stirring speed is 200-600 r / min; The solvent is at least one of N-methylpyrrolidone solvent, N,N-dimethylformamide and dimethyl sulfoxide; In step (2), the vacuum drying temperature is 90-150 °C and the time is 10-20 h.

[0024] In this invention, as a preferred embodiment, the method for preparing the zinc-ion battery is as follows: Stainless steel battery casing placement: Place the stainless steel battery casing (usually the bottom of the battery, the stainless steel battery casing of the present invention is model 2016) in the assembly mold or fixture; Positive electrode placement: Place the positive electrode flat inside the stainless steel battery casing, ensuring full contact; Separator placement: Place the separator flat on top of the positive electrode plate, ensuring complete coverage of the positive electrode plate and avoiding wrinkles or damage; Negative electrode placement: Place the zinc negative electrode with the amino acid adsorption enhancement layer on its surface flat on top of the separator, ensuring full contact with the separator; Electrolyte addition: Add an appropriate amount of electrolyte precisely according to the designed capacity. The electrolyte should evenly wet the electrodes and diaphragm, but avoid over-addition that could cause overflow. Stainless steel pad placement: Place stainless steel pads on top of the negative electrode to fill the gaps inside the battery and prevent the electrode from shaking and causing a short circuit. Negative terminal cover placement: Place the negative terminal cover (top of the battery) on top of the stainless steel pad and align it with the stainless steel battery casing; Sealing: The battery is sealed using a special press.

[0025] The beneficial effects of the technical solution of the present invention are as follows: 1. By enhancing the effectiveness of the amino acid additive, this invention enables the zinc anode obtained in this invention to achieve rapid zinc ion transfer kinetics, uniform zinc deposition, a highly reversible zinc deposition / stripping process, and effective suppression of parasitic reactions. The zinc anode of this invention exhibits excellent cycle stability, and the zinc-ion battery possesses ultra-long cycle life, low economic cost, and high safety.

[0026] 2. The optimized zinc anode of the present invention uses amino acids (such as methionine) as additives and anions (such as sulfate) in the hydrophilic zinc salt as electrolyte salts as reinforcing agents for amino acid additives. No additional reinforcing agents are required, and the reinforcing mechanism and process are simple.

[0027] 3. This invention uses amino acid additives as the adsorption layer on the zinc surface, which not only yields an optimized zinc anode but also an optimized zinc-ion battery energy storage device. The adsorption layer on the zinc surface is strengthened for the first time by hydrophilic anions, which is original. Extensive practical tests show that the amino acid additives (such as methionine additives) strengthened by hydrophilic anions (such as sulfate) described in this invention have a good regulatory effect on the zinc anode, and the optimized zinc anode and the cycle stability of the zinc-ion battery are significantly improved.

[0028] 4. The main raw materials involved in this invention, namely amino acids, hydrophilic zinc salts, diaphragms, and zinc sheets, are all inexpensive, non-toxic, and harmless. The experimental operation is also simple. Therefore, the entire process is relatively simple, low-cost, and environmentally friendly. As a result, this invention is particularly suitable for large-scale commercial production and has excellent commercial application prospects.

[0029] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0030] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings.

[0031] Figure 1 This diagram illustrates the enhancement mechanism of sulfate anions on methionine and the effect of enhancement in a method for improving the effectiveness of amino acid additives provided by the present invention.

[0032] Figure 2 The infrared spectra of bare zinc metal (i.e., the original zinc foil) and bare zinc metal after being immersed in an electrolyte containing methionine additive for 7 days are shown in Embodiment 1 of the present invention (i.e., the immersed zinc foil).

[0033] Figure 3(a) shows a scanning electron microscope image of bare zinc metal provided in Example 1 of the present invention after being immersed in an electrolyte without methionine additive for 7 days.

[0034] Figure 3(b) shows a scanning electron microscope image of the bare zinc metal provided in Example 1 of the present invention after being immersed in an electrolyte containing methionine additive for 7 days.

[0035] Figure 4 The binding energies of sulfate and water, amino groups on methionine and water, and carboxyl groups on methionine and water are shown.

[0036] Figure 5 The adsorption energies of naked methionine and hydrated methionine used in Example 1 on the surface of naked zinc metal are shown.

[0037] Figure 6 The zinc symmetric cell prepared using the zinc anode of Example 1 and the zinc symmetric cell prepared using the zinc anode of Comparative Example 1 are shown at a current density of 1 mA cm⁻¹. -2 , with a capacity of 1 mAh cm -2 The following is a graph showing the cyclic stability of the circuit.

[0038] Figure 7 The zinc symmetric battery prepared using the zinc anode of Example 1 and the zinc symmetric battery prepared using the zinc anode of Comparative Example 1 are shown, with a capacity of 1 mAh cm⁻¹. -2 The following is a graph showing the rate performance.

[0039] Figure 8(a) shows a scanning electron microscope image of the zinc anode of the zinc symmetric battery prepared using the zinc anode of Comparative Example 1 after 50 cycles.

[0040] Figure 8(b) shows a scanning electron microscope image of the zinc anode of a zinc symmetric battery prepared using the zinc anode of Example 1 after 50 cycles.

[0041] Figure 9The zinc-ion full cell provided in Example 1 and the zinc-ion full cell in Comparative Example 1 are shown at a current density of 2 A g. -1 The following is a cycle life analysis diagram (the “Zinc / / Vanadium dioxide” in the diagram represents the zinc negative and positive electrode sheets of Example 1). Detailed Implementation

[0042] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0043] The following embodiments: Methionine, specifically L-methionine, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., item number: M6246, CAS item number: 63-68-3; The bare zinc metal was purchased from Guangdong Zhuguang New Energy Technology Co., Ltd. (Kelode), CAS No.: 7440-66-6.

[0044] Example 1

[0045] This embodiment provides a method for improving the effectiveness of amino acid additives, the method comprising the following steps: S1: Mix methionine, zinc sulfate and water, and stir (stirring time is 0.5 h, stirring speed is 300 r / min) to obtain an electrolyte solution containing amino acid additives; Based on the total weight of the electrolyte solution containing amino acid additives, the content of methionine is 0.94 wt%, the content of water is 62.89 wt%, and the content of zinc sulfate is 36.17 wt%.

[0046] S2: Immerse the bare zinc metal and let it stand in the electrolyte solution containing amino acid additives; and during the standing process, intermittently stir the upper layer of electrolyte solution containing amino acid additives. The settling time is 36 h; the intermittent stirring is: during the settling process, the upper layer of electrolyte solution containing amino acid additives is stirred once every 2 h.

[0047] S3: After step S2 has been completed, the zinc anode is rinsed with water and air-dried to obtain a zinc anode with an amino acid adsorption enhancement layer on its surface. In this embodiment: The bare zinc metal is in the form of a thin circular sheet, 20 μm thick and 1 cm in diameter; The volume of the electrolyte solution containing amino acid additives used in step S2 is 60 mL; The volume of deionized water used for rinsing is 70 mL, and the natural air-drying time is 8 hours.

[0048] This embodiment also provides a zinc-ion battery, wherein the negative electrode of the zinc-ion battery is a zinc negative electrode with an amino acid adsorption reinforcement layer on its surface, as described in this embodiment.

[0049] The zinc-ion battery also includes an electrolyte; the electrolyte of the zinc-ion battery is composed of the following components: methionine, water and zinc sulfate, wherein the concentration of methionine in the electrolyte is 0.1 mol / L and the concentration of zinc sulfate in the electrolyte is 2 mol / L.

[0050] The zinc-ion battery has a coin cell structure, and the preparation method of the zinc-ion battery is as follows: Preparation of the positive electrode sheet: The polyvinylidene fluoride, acetylene black, vanadium dioxide, and an appropriate amount of N-methylpyrrolidone solvent are mixed and stirred evenly to obtain a positive electrode slurry; the positive electrode slurry is evenly coated onto the surface of a titanium foil current collector using a coating machine, placed in a vacuum drying oven at 120 °C, and heated to remove the N-methylpyrrolidone solvent; the slurry is then cut into sheets to obtain the positive electrode sheet; wherein, based on the total weight of the positive electrode slurry of the positive electrode sheet, the positive electrode slurry of the positive electrode sheet comprises: 10 wt% polyvinylidene fluoride, 20 wt% acetylene black, and 70 wt% vanadium dioxide; Stainless steel battery casing placement: Place the stainless steel battery casing (usually the bottom of the battery; the stainless steel battery casing described in this invention is model 2016 with a thickness of 500 μm) in the assembly mold or fixture. Positive electrode placement: Place the positive electrode (a thin, round sheet with a diameter of 1 cm and a thickness of 30 μm) flat inside the stainless steel battery casing, ensuring full contact; Separator placement: Place the separator flat on top of the positive electrode plate, ensuring complete coverage of the positive electrode plate and avoiding wrinkles or damage; Negative electrode placement: The zinc negative electrode with the amino acid adsorption enhancement layer on its surface in this embodiment is placed flat on top of the separator, ensuring full contact with the separator; Electrolyte addition: Add an appropriate amount of electrolyte precisely according to the designed capacity. The electrolyte should evenly wet the electrodes and diaphragm, but avoid over-addition that could cause overflow. Stainless steel pad placement: Place stainless steel pads on top of the negative electrode to fill the gaps inside the battery and prevent the electrode from shaking and causing a short circuit. Negative terminal cover placement: Place the negative terminal cover (top of the battery) on top of the stainless steel pad and align it with the stainless steel battery casing; Sealing: The battery is sealed using a special press. The pressure of the press used to seal the button cell battery structure is 1 MPa.

[0051] Comparative Example 1

[0052] This comparative example provides a zinc-ion battery, which differs from Example 1 only in that: The negative electrode of the zinc-ion battery in this comparative example is bare zinc metal; The electrolyte of the zinc-ion battery in this comparative example consists of the following components: water and zinc sulfate, and the concentration of zinc sulfate in the electrolyte of this comparative example is 2 mol / L.

[0053] like Figure 2 The image shows the infrared spectra of bare zinc metal (i.e., the original zinc foil) and bare zinc metal after immersion in an electrolyte containing methionine additive (the electrolyte containing methionine additive is the electrolyte of the zinc-ion battery described in this embodiment, where the concentration of methionine in the electrolyte is 0.1 mol / L and the concentration of zinc sulfate in the electrolyte is 2 mol / L, the same below) for 7 days (i.e., the zinc foil after immersion). Figure 2 As can be seen, after the original zinc foil was immersed in an electrolyte containing methionine additive, the characteristic peak of methionine appeared on its surface, indicating that methionine was successfully adsorbed on the surface of the bare zinc metal (i.e., the original zinc foil).

[0054] Figure 3(a) shows a scanning electron microscope image of bare zinc metal provided in Example 1 of the present invention after being immersed in an electrolyte without methionine additive (the electrolyte without methionine additive is a solution composed of zinc sulfate and water, wherein the concentration of zinc sulfate in the electrolyte without methionine additive is 2 mol / L, the same below) for 7 days; as can be seen from the inset in the upper left corner of Figure 3(a), the surface of the bare zinc metal immersed in the electrolyte without methionine additive is white and has lost its original metallic luster. As can be seen from the scanning electron microscope image in Figure 3(a), many flakes of different sizes have accumulated on the surface of the bare zinc metal, indicating that the bare zinc metal has undergone severe corrosion; Figure 3(b) shows a scanning electron microscope (SEM) image of bare zinc metal provided in Example 1 of this invention after immersion in an electrolyte containing methionine additive (the electrolyte containing methionine additive is the electrolyte of the zinc-ion battery described in this example, where the concentration of methionine in the electrolyte of the zinc-ion battery is 0.1 mol / L and the concentration of zinc sulfate in the electrolyte of the zinc-ion battery is 2 mol / L) for 7 days. The inset at the top left of Figure 3(b) shows that the bare zinc metal immersed in the electrolyte containing methionine additive retains its original metallic luster. The SEM image in Figure 3(b) shows that the surface of the bare zinc metal after immersion is smooth and flat, indicating that methionine adsorbed on the zinc surface has a good protective effect on the bare zinc metal.

[0055] like Figure 4 The figure shows the binding energies of sulfate with water, amino groups on methionine with water, and carboxyl groups on methionine with water; from Figure 4 As can be seen, the ability of sulfate to bind water is much stronger than that of the carboxyl or amino groups of methionine to bind water. This means that sulfate can remove water molecules around methionine, thus giving methionine a weak hydration structure.

[0056] like Figure 5 The figure shows the adsorption energies of naked methionine and hydrated methionine on the surface of bare zinc metal used in Example 1; from Figure 5 As can be seen, compared with naked methionine molecules, the binding energy of hydrated methionine molecules on the zinc surface is reduced by 1.48 eV. This indicates that the affinity of hydrated methionine for the zinc surface is significantly reduced, which also shows that the water-removing effect of sulfate can indeed enhance the affinity of the methionine adsorption layer on the zinc surface.

[0057] like Figure 6 As shown, the zinc symmetric cell prepared using the zinc anode of Example 1 and the zinc symmetric cell prepared using the zinc anode of Comparative Example 1 are shown at a current density of 1 mA cm⁻¹. -2 , with a capacity of 1 mAh cm -2 The following is a cyclic stability plot; from Figure 6 As can be seen, with the enhancement effect of adding methionine and sulfate on methionine, the zinc symmetric battery prepared using the zinc anode of Example 1 has a cycle stability of 3200 h, which is significantly higher than the 176 h of the zinc symmetric battery prepared using the zinc anode of Comparative Example 1. This indicates that with the enhancement effect of adding methionine and sulfate on methionine, the cycle stability of the zinc symmetric battery prepared using the zinc anode of Example 1 can be significantly improved.

[0058] like Figure 7 As shown, the zinc symmetric battery prepared using the zinc anode of Example 1 and the zinc symmetric battery prepared using the zinc anode of Comparative Example 1 have a capacity of 1 mAh cm⁻¹.-2 The following is a graph showing the rate performance; from Figure 7 As can be seen from the data, the zinc symmetric cell prepared using the zinc anode of Comparative Example 1, after passing through a high current density (10 mA cm⁻¹), exhibits better performance. -2 5 mA cm -2 After cycling, the battery began to short-circuit and fail, which meant unsatisfactory rate performance. However, the zinc symmetric battery prepared using the zinc anode of Example 1 showed superior rate performance, exhibiting excellent cycle stability and reversibility at various current densities. This indicates that the addition of methionine and the water-removing effect of sulfate on methionine synergistically improved the rate performance of the zinc symmetric battery prepared using the zinc anode of Example 1.

[0059] As shown in Figure 8(a), a zinc symmetric cell prepared using the zinc anode of Comparative Example 1 was cycled 50 times (at a current density of 1 mA cm⁻¹). -2 , with a capacity of 1 mAh cm -2 The scanning electron microscope image of the zinc anode of the battery after (below) shows that the zinc anode of the zinc symmetric battery prepared using the zinc anode of Comparative Example 1 showed significant deterioration on the surface after 50 cycles, with an uneven surface and accumulation of sheet-like byproducts of varying sizes.

[0060] As shown in Figure 8(b), a zinc symmetric cell prepared using the zinc anode of Example 1 is cycled 50 times (at a current density of 1 mA cm⁻¹). -2 , with a capacity of 1 mAh cm -2 The scanning electron microscope image of the zinc anode of the battery after (below) shows that the zinc anode of the zinc symmetric battery prepared using the zinc anode of Example 1 exhibits a smooth surface morphology after 50 cycles. This is mainly due to the addition of methionine and the water-removing effect of sulfate on methionine, which makes the methionine adsorption layer have better affinity on the zinc surface, thus better protecting the zinc anode. At the same time, the water-removing effect of methionine gives zinc ions a weak solvation structure, reduces side reactions such as hydrogen evolution, and promotes the uniform deposition of zinc ions on the zinc surface, which is also conducive to the formation of a uniform surface morphology of the zinc anode.

[0061] like Figure 9 As shown, the zinc-ion full cell provided in Example 1 (i.e., the positive electrode of Example 1 + the zinc negative electrode of Example 1) and the zinc-ion full cell of Comparative Example 1 (the positive electrode of Comparative Example 1 + the zinc negative electrode of Comparative Example 1) are tested at a current density of 2 A g. -1 The following is a cycle life analysis diagram; by Figure 9It can be seen that the zinc-ion full battery of Comparative Example 1 has a faster capacity decay, with the battery capacity only reaching 21% after 2000 cycles; while the zinc-ion full battery provided in Example 1 still maintains a capacity of 46% after 2000 cycles, and the capacity decay process is slow. This indicates that the cycle stability of the zinc-ion full battery of Example 1 is significantly improved by the addition of methionine and the water-removing effect of sulfate on methionine.

[0062] Example 2

[0063] The only difference between this embodiment and Embodiment 1 is that: Based on the total weight of the electrolyte solution containing amino acid additives, the content of methionine is 0.84 wt%, the content of water is 62.79 wt%, and the content of zinc sulfate is 36.37 wt%. The settling time is 24 hours; The thickness of the zinc anode with the amino acid adsorption enhancement layer on its surface is 10 μm. The pressure of the press used to seal the button cell structure is 1.5 MPa.

[0064] Example 3

[0065] The only difference between this embodiment and Embodiment 1 is that: Based on the total weight of the electrolyte solution containing amino acid additives, the content of methionine is 0.80 wt%, the content of water is 62.99 wt%, and the content of zinc sulfate is 36.11 wt%. The settling time is 26 hours; The thickness of the zinc anode with the amino acid adsorption enhancement layer on its surface is 15 μm. The pressure of the press used to seal the button cell structure is 2 MPa.

[0066] Example 4

[0067] The only difference between this embodiment and Embodiment 1 is that: Based on the total weight of the electrolyte solution containing amino acid additives, the content of methionine is 0.90 wt%, the content of water is 62.55 wt%, and the content of zinc sulfate is 36.55 wt%. The settling time is 30 hours; The thickness of the zinc anode with the amino acid adsorption enhancement layer on its surface is 25 μm. The pressure of the press used to seal the button cell structure is 2.5 MPa.

[0068] Example 5

[0069] The only difference between this embodiment and Embodiment 1 is that: Based on the total weight of the electrolyte solution containing amino acid additives, the content of methionine is 0.92 wt%, the content of water is 63.09 wt%, and the content of zinc sulfate is 35.99 wt%. The settling time is 32 hours; The thickness of the zinc anode with the amino acid adsorption enhancement layer on its surface is 30 μm. The pressure of the press used to seal the button cell structure is 2.75 MPa.

[0070] Example 6

[0071] The only difference between this embodiment and Embodiment 1 is that: Based on the total weight of the electrolyte solution containing amino acid additives, the content of methionine is 0.98 wt%, the content of water is 62.66 wt%, and the content of zinc sulfate is 36.36 wt%. The settling time is 40 hours; The thickness of the zinc anode with the amino acid adsorption enhancement layer on its surface is 40 μm. The pressure of the press used to seal the button cell structure is 3 MPa.

[0072] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for improving the effectiveness of amino acid additives, characterized in that, The method includes the following steps: S1: Mix amino acids, hydrophilic zinc salts and water, stir, and obtain an electrolyte solution containing amino acid additives; S2: Immerse the bare zinc metal in the electrolyte solution containing the amino acid additive and let it stand; and during the standing process, stir the electrolyte solution containing the amino acid additive intermittently. S3: After step S2 has been completed, the zinc anode is rinsed with water and air-dried to obtain a zinc anode with an amino acid adsorption enhancement layer on its surface.

2. The method for improving the effectiveness of amino acid additives according to claim 1, wherein, Based on the total weight of the electrolyte solution containing amino acid additives, the content of amino acids is 0.8-1.1 wt%, the content of water is 55-70 wt%, and the content of hydrophilic zinc salt is 35-50 wt%.

3. The method for improving the effectiveness of amino acid additives according to claim 1, wherein, The amino acid is at least one of methionine, proline, and glycine; The hydrophilic zinc salt is at least one of zinc sulfate, zinc acetate, and zinc dihydrogen phosphate.

4. The method for improving the effectiveness of amino acid additives according to claim 1, wherein, In step S1: the stirring time is 0.5-2 h, and the stirring speed is 200-500 r / min.

5. The method for improving the effectiveness of amino acid additives according to claim 1, wherein, In step S2: The settling time is 24-48 hours; The intermittent stirring is: during the settling process, the electrolyte solution containing amino acid additives is stirred once every 1-3 hours.

6. The method for improving the effectiveness of amino acid additives according to claim 5, wherein, The bare zinc metal is in the form of thin circular sheets, with a thickness of 10-50 μm and a diameter of 1-1.2 cm; The volume of the electrolyte solution containing amino acid additives used in step S2 is 50-70 mL.

7. The zinc anode with an amino acid adsorption enhancement layer on its surface obtained by the method for improving the effectiveness of amino acid additives according to any one of claims 1-6.

8. A zinc-ion battery, characterized in that, The negative electrode of the zinc-ion battery is the zinc negative electrode with an amino acid adsorption reinforcement layer on its surface as described in claim 7.

9. The zinc-ion battery according to claim 8, wherein, The zinc-ion battery further includes an electrolyte; the electrolyte of the zinc-ion battery includes the following components: amino acids, water and a hydrophilic zinc salt, wherein the concentration of amino acids in the electrolyte is 0.05-0.15 mol / L, and the concentration of the hydrophilic zinc salt in the electrolyte is 1.5-2.5 mol / L.

10. The zinc-ion battery according to claim 8, wherein, The zinc-ion battery has a button cell structure and further includes: a positive electrode, a separator, a stainless steel gasket, and a stainless steel battery casing. The pressure of the press used to seal the button cell structure is 1-3 MPa.

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