Aqueous zinc metal battery electrolyte and zinc metal battery

Abstract

The invention discloses an aqueous zinc metal battery electrolyte and a zinc metal battery, and belongs to the technical field of batteries, the aqueous zinc metal battery electrolyte comprises L-pyroglutamic acid, zinc salt and water, and the concentration of the L-pyroglutamic acid in the aqueous zinc metal battery electrolyte is 0.01-0.5 mol / L. According to the water-based zinc metal battery electrolyte disclosed by the invention, the L-pyroglutamic acid with a specific concentration is added, and after the L-pyroglutamic acid is introduced into the water-based zinc metal battery electrolyte, the L-pyroglutamic acid has the functions of reconstructing a hydrogen bond network and creating a strong acid environment; the three problems of hydrogen evolution side reaction, corrosion reaction and zinc dendrite growth at a zinc negative electrode-electrolyte interface can be solved, and the specific capacity, coulombic efficiency and cycle life of the zinc metal battery are effectively improved.

Description

Technical Field

[0001] This application relates to the field of materials chemistry technology, specifically an aqueous zinc metal battery electrolyte and a zinc metal battery. Background Technology

[0002] Lithium-ion batteries (LIBs) play a crucial role in electronic communication products, energy storage power stations, and electric vehicles (EVs), but their high pollution, flammability, explosiveness, and high manufacturing costs remain unresolved issues. In recent years, aqueous zinc metal batteries (ZMBs) have attracted widespread attention as a promising alternative to lithium-ion batteries due to the significant advantages of zinc metal anodes (high specific capacity of 820 mAh·g⁻¹, volumetric specific capacity of 5855 mAh·cm⁻³, and low redox potential (-0.76V vs. SHE.)) and aqueous electrolytes (high ionic conductivity and high safety).

[0003] However, hydrogen evolution side reactions, corrosion reactions, and zinc dendrite growth at the zinc anode-electrolyte interface are the three major problems hindering the practical application of zinc macromolecules (ZMBs). These three problems are interconnected and mutually reinforcing, jointly causing a continuous decline in the performance of ZMBs. Therefore, modifying the ZMBs by inhibiting hydrogen evolution and corrosion reactions can be an effective approach. The hydrogen evolution reaction is the process by which active water molecules gain electrons on the zinc anode surface and are reduced to generate hydrogen molecules; the corrosion reaction is the process by which zinc ions, sulfate ions, and a high concentration of hydroxide ions locally present on the zinc anode surface react to form basic zinc sulfate, leading to zinc anode corrosion. Therefore, one approach to inhibiting hydrogen evolution is to reduce the activity of water molecules in the electrolyte and form new hydrogen bonds, which can achieve this effect; another approach to inhibiting corrosion is to create a more acidic electrolyte environment.

[0004] Therefore, this application is submitted. Summary of the Invention

[0005] The purpose of this application is to overcome the shortcomings of the existing technology and provide an aqueous zinc metal battery electrolyte and a zinc metal battery. The aqueous zinc metal battery electrolyte described in this application can solve three major problems at the zinc anode-electrolyte interface: hydrogen evolution side reaction, corrosion reaction, and zinc dendrite growth, effectively improving the specific capacity, coulombic efficiency, and cycle life of zinc metal batteries.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: An aqueous zinc metal battery electrolyte comprises L-pyroglutamic acid, zinc salt and water, wherein the concentration of L-pyroglutamic acid in the aqueous zinc metal battery electrolyte is 0.01~0.5 mol / L.

[0007] The aqueous zinc metal battery electrolyte described in this application incorporates a specific concentration of L-pyroglutamic acid. After being introduced into the electrolyte, L-pyroglutamic acid forms new hydrogen bonds with water molecules and participates in the construction of a new hydrogen bond network. The formation of new hydrogen bonds with L-pyroglutamic acid significantly reduces the activity of water molecules, thus greatly weakening the hydrogen evolution reaction occurring on the zinc anode surface. Furthermore, the L-pyroglutamic acid exhibits weak acidity in water (pH = 1.7), with a pKa value of 3.32, lower than the pKa of acetic acid (4.75) and higher than the pKa of phosphoric acid (2.12), classifying it as a moderately strong acid. Compared to simple soluble zinc salts, L-pyroglutamic acid creates a more acidic environment (pH = 2.2) in the electrolyte, which can effectively inhibit the occurrence of corrosion reactions and the formation of its product, basic zinc sulfate, and maintain the uniformity and flatness of the zinc anode surface. The L-pyroglutamic acid has the function of reconstructing hydrogen bond networks and creating a strongly acidic environment, which can solve three major problems at the zinc anode-electrolyte interface: hydrogen evolution side reaction, corrosion reaction, and zinc dendrite growth, effectively improving the specific capacity, coulombic efficiency, and cycle life of zinc metal batteries.

[0008] As an embodiment of this application, the concentration of L-pyroglutamic acid in the aqueous zinc metal battery electrolyte is 0.02~0.05 mol / L. In particular, when the concentration of L-pyroglutamic acid in the aqueous zinc metal battery electrolyte is within this range, it can further suppress the three major problems at the negative electrode-electrolyte interface: hydrogen evolution side reaction, corrosion reaction, and zinc dendrite growth, thereby further improving the specific capacity, coulombic efficiency, and cycle life of the zinc metal battery.

[0009] As an embodiment of this application, the zinc salt includes at least one of zinc sulfate, zinc chloride, zinc bromide, zinc nitrate, zinc acetate, and zinc trifluoromethanesulfonate.

[0010] As an embodiment of this application, the concentration of the zinc salt in the aqueous zinc metal battery electrolyte is 1~3 mol / L. In particular, when the concentration of the zinc salt is within this range, the L-pyroglutamic acid can better perform its function of reconstructing hydrogen bond networks and creating a strongly acidic environment.

[0011] As an embodiment of this application, the zinc salt includes zinc sulfate.

[0012] As an embodiment of this application, the concentration of L-pyroglutamic acid in the aqueous zinc metal battery electrolyte is 0.05 mol / L; the concentration of zinc salt in the aqueous zinc metal battery electrolyte is 2 mol / L. In particular, when the concentrations of both are within this range, it can effectively solve the three major problems of hydrogen evolution side reaction, corrosion reaction and zinc dendrite growth at the zinc anode-electrolyte interface, and better improve the specific capacity, coulombic efficiency and cycle life of zinc metal batteries.

[0013] This application also provides a zinc metal battery, including the aqueous zinc metal battery electrolyte described above.

[0014] As an embodiment of this application, it further includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode; the negative electrode is zinc metal, and the positive electrode includes a positive current collector and a positive active material layer located on at least one surface of the positive current collector, the positive active material layer including a positive active material, the positive active material including an intercalation compound.

[0015] As an embodiment of this application, the zinc metal includes at least one of zinc plate, zinc sheet, zinc foil, and zinc foam; the intercalation compound includes at least one of manganese-based materials, vanadium-based materials, and Prussian blue analogues; and the diaphragm includes a glass fiber diaphragm.

[0016] As an embodiment of this application, the manganese-based material includes MnO2, the vanadium-based material includes V2O5, and the Prussian blue analogue includes Fe4[Fe(CN)6]3.

[0017] As an embodiment of this application, the vanadium-based material includes V2O5.

[0018] The beneficial effects of this application are as follows: The aqueous zinc metal battery electrolyte described in this application, by adding a specific concentration of L-pyroglutamic acid, allows L-pyroglutamic acid to form new hydrogen bonds with water molecules and participate in the construction of a new hydrogen bond network. After forming new hydrogen bonds with L-pyroglutamic acid, the activity of water molecules is greatly reduced. Therefore, the hydrogen evolution reaction occurring on the zinc anode surface is also greatly weakened. Furthermore, the L-pyroglutamic acid exhibits weak acidity in water (pH = 1.7), with a pKa value of 3.32, lower than the pKa of acetic acid (4.75) and higher than the pKa of phosphoric acid (2.12), making it a moderately strong acid. Compared to simple soluble zinc salts, L-pyroglutamic acid creates a more acidic environment (pH = 2.2) in the electrolyte, which can effectively inhibit the occurrence of corrosion reactions and the formation of its product, basic zinc sulfate, and maintain the uniformity and flatness of the zinc anode surface. The L-pyroglutamic acid has the function of reconstructing hydrogen bond networks and creating a strongly acidic environment, which can solve three major problems at the zinc anode-electrolyte interface: hydrogen evolution side reaction, corrosion reaction, and zinc dendrite growth, effectively improving the specific capacity, coulombic efficiency, and cycle life of zinc metal batteries. Attached Figure Description

[0019] Figure 1 The voltage-time curves for the stripping / deposition cycle process of Zn||Zn symmetric cells in Example 1 and Comparative Example 1 are shown below. Figure 1 (a) is a voltage-time curve of the stripping / deposition cycle process of the Zn||Zn symmetric cell in Example 1. Figure 1 (b) is a voltage-time curve of the stripping / deposition cycle of the Zn||Zn symmetric cell in Comparative Example 1.

[0020] Figure 2 The graph shows the coulombic efficiency versus cycle number curves for the stripping / deposition cycle process of the Zn||Cu half-cells in Example 2 and Comparative Example 2, where... Figure 2 (a) is a coulombic efficiency-cycle count curve of the stripping / deposition cycle process of the Zn||Cu half-cell in Example 2. Figure 2 (b) is a coulombic efficiency-cycle number curve of the stripping / deposition cycle process of the Zn||Cu half-cell in Comparative Example 2.

[0021] Figure 3 The graph shows the capacity decay curves of the Zn||V2O5 full cells of Example 3 and Comparative Example 3 during the charge-discharge cycle process. Figure 3 (a) is a capacity decay curve of the Zn||V2O5 full cell in Example 3 during charge-discharge cycles. Figure 3 (b) shows the capacity decay curve of the Zn||V2O5 full cell in Comparative Example 3 during the charge-discharge cycle.

[0022] Figure 4 The capacity decay curves of Zn||V2O5 full cells during charge-discharge cycles are shown when using an aqueous zinc metal battery electrolyte additive (L-pyroglutamic acid) at the same concentration (0.05 mol / L) and other aqueous zinc metal battery electrolyte additives (L-glutamic acid, monosodium glutamate, L-proline, etc.).

[0023] Figure 5 The capacity decay curves of Zn||V2O5 full cells during charge-discharge cycles are shown when using different concentrations (0 mol / L, 0.01 mol / L, 0.02 mol / L, 0.05 mol / L) of aqueous zinc metal battery electrolyte additive (L-pyroglutamic acid).

[0024] Figure 6 The study investigated the changes in the proportions of different types of hydrogen bond components in the electrolyte with and without the use of an aqueous zinc metal battery electrolyte additive (L-pyroglutamic acid); the comparison of solution freezing conditions; and the hydrogen evolution polarization curves and hydrogen evolution current values ​​of the Zn||Cu half-cell.

[0025] Figure 7 The pH change of the electrolyte with and without the novel aqueous zinc metal battery electrolyte additive (L-pyroglutamic acid), which reconstructs the hydrogen bond network and creates a strongly acidic environment; the distribution of corrosion products on the zinc anode surface after soaking in the electrolyte for 3 days before and after the addition of L-pyroglutamic acid; and the Tafel polarization curves and corrosion current values ​​of the Zn||Zn symmetric cell. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0028] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0029] In this application, there are no particular restrictions on the specific dispersion and mixing methods.

[0030] Unless otherwise specified, all components, raw materials, or instruments used in the embodiments and comparative examples of this application are commercially available, and the components and raw materials used in each parallel experiment are the same.

[0031] The following embodiments are provided to facilitate understanding of this application. These embodiments are provided not to limit the scope of the claims.

[0032] Example 1 A method for preparing a zinc metal battery includes the following steps: S1. At room temperature, 5.7510 g of zinc sulfate heptahydrate and 0.0648 g of L-pyroglutamic acid were added to 7.5 mL of deionized water and stirred at 500 rpm for 6 h to prepare an electrolyte containing 2 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid (abbreviated as With LPA).

[0033] S2. A Zn||Zn symmetric cell of model CR2032 is assembled using 100 μL of electrolyte containing 2 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid, two 100 μm thick zinc foil negative electrode sheets (16 mm in diameter), a glass fiber separator, positive and negative electrode sheets, battery casing, gaskets, and springs.

[0034] S3. Using an assembled Zn||Zn symmetric cell at a current density of 2 mA·cm⁻¹ -2 The surface capacity is 2 mAh·cm -2 Under these conditions, long-term stripping / deposition cycle tests were conducted.

[0035] Test results are as follows Figure 1 As shown in (a), after using an aqueous zinc metal battery electrolyte additive (L-pyroglutamic acid), the cycle life of the Zn||Zn symmetric battery is as high as 5000 h or more, and the polarization voltage remains stable for a long time.

[0036] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that L-pyroglutamic acid was not added to Comparative Example 1, but everything else is the same.

[0037] A method for preparing a zinc metal battery includes the following steps: S1. At room temperature, add 5.7510 g of zinc sulfate heptahydrate to 7.5 mL of deionized water and stir at 500 rpm for 6 h to prepare an electrolyte containing 2 mol / L zinc sulfate (this electrolyte is referred to as Without LPA).

[0038] S2. A Zn||Zn symmetric cell of model CR2032 is assembled using 100 μL of electrolyte containing 2 mol / L zinc sulfate, two 100 μm thick zinc foil negative electrode sheets (16 mm in diameter), a glass fiber separator, positive and negative electrode sheets, battery casing, gaskets, and springs.

[0039] S3. Using an assembled Zn||Zn symmetric cell at a current density of 2 mA·cm⁻¹ -2 The surface capacity is 2 mAh·cm -2 Under these conditions, long-term stripping / deposition cycle tests were conducted.

[0040] Test results are as follows Figure 1 As shown in (b), without the use of aqueous zinc metal battery electrolyte additive (L-pyroglutamic acid), the cycle life of the Zn||Zn symmetric battery is only 220 h, and short circuits of the battery occur.

[0041] Because water molecules are highly reactive in a single soluble zinc salt solution, they readily gain electrons at the zinc anode-electrolyte interface, leading to the hydrogen evolution reaction (HER). This HER causes a localized increase in hydroxide ion concentration and pH at the zinc anode-electrolyte interface, resulting in corrosion and the formation of the corrosion product, basic zinc sulfate. The HER and corrosion reactions further promote zinc dendrite growth, ultimately causing a short circuit and shortening the battery's lifespan. In the figure, a sudden voltage drop followed by a prolonged period at a certain value indicates a short circuit and the end of the battery's lifespan. Therefore, its cycle life is 220 hours.

[0042] As can be seen from the comparison between Example 1 and Comparative Example 1, in the zinc metal battery system of this application, the addition of L-pyroglutamic acid in the electrolyte can significantly improve the cycle life and the polarization voltage remains stable for a long time.

[0043] Example 2 A method for preparing a zinc metal battery includes the following steps: S1. At room temperature, 5.7510 g of zinc sulfate heptahydrate and 0.0648 g of L-pyroglutamic acid were added to 7.5 mL of deionized water and stirred at 500 rpm for 6 h to prepare an electrolyte containing 2 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid (abbreviated as With LPA).

[0044] S2. A Zn||Cu half-cell of model S2032 is assembled using 100 μL of electrolyte containing 2 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid, a 100 μm thick zinc foil negative electrode (16 mm in diameter), a glass fiber separator, a 16 μm thick copper foil negative electrode (16 mm in diameter), a negative electrode battery shell, gaskets, springs, etc.

[0045] S3. Using the assembled Zn||Cu half-cell at a current density of 1 mA·cm⁻¹ -2 The surface capacity is 1 mAh·cm -2 The stripping / deposition cycle test was performed under the condition that the charging cutoff voltage was 1 V.

[0046] Test results are as follows Figure 2 As shown in (a), under the premise that large fluctuations in coulombic efficiency are used as the sign of battery failure (battery reaching cycle life), it can be seen that its cycle life is more than 250 cycles and the average coulombic efficiency is 99.66%.

[0047] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that L-pyroglutamic acid was not added to Comparative Example 2, but everything else is the same.

[0048] A method for preparing a zinc metal battery includes the following steps: S1. At room temperature, add 5.7510 g of zinc sulfate heptahydrate to 7.5 mL of deionized water and stir at 500 rpm for 6 h to prepare an electrolyte containing 2 mol / L zinc sulfate (this electrolyte is referred to as Without LPA).

[0049] S2. A Zn||Cu half-cell of model CR2032 is assembled using 100 μL of electrolyte containing 2 mol / L zinc sulfate, a 100 μm thick zinc foil negative electrode (16 mm in diameter), a glass fiber separator, a 16 μm thick copper foil negative electrode (16 mm in diameter), a negative electrode battery shell, gaskets, springs, etc.

[0050] S3. Using the assembled Zn||Cu half-cell at a current density of 1 mA·cm⁻¹ -2 The surface capacity is 1 mAh·cm -2 The stripping / deposition cycle test was performed under the condition that the charging cutoff voltage was 1 V.

[0051] Test results are as follows Figure 2 As shown in (b), under the premise that a large fluctuation in coulombic efficiency is used as the sign of battery failure (battery reaching cycle life), it can be seen that without the use of aqueous zinc metal battery electrolyte additive (L-pyroglutamic acid), the cycle life of Zn||Cu half cell is 122 cycles and the average coulombic efficiency is 98.30%.

[0052] By comparing Example 2 with Comparative Example 2, we can conclude that the addition of L-pyroglutamic acid to the electrolyte in the zinc metal battery system of this application has a significant effect on improving the cycle life and average coulombic efficiency of the Zn||Cu half-cell.

[0053] Example 3 A method for preparing a zinc metal battery includes the following steps: S1. At room temperature, 5.7510 g of zinc sulfate heptahydrate and 0.0648 g of L-pyroglutamic acid were added to 7.5 mL of deionized water and stirred at 500 rpm for 6 h to prepare an electrolyte containing 2 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid (abbreviated as With LPA).

[0054] S2. An electrolyte containing 80 μL of zinc sulfate at a concentration of 2 mol / L and L-pyroglutamic acid at a concentration of 0.05 mol / L, a 100 μm thick zinc foil negative electrode (16 μm in diameter), a glass fiber diaphragm, and a 12 mm diameter positive electrode with graphite paper as the current collector and V₂O₅ as the positive electrode active material with a loading of 1 mg·cm⁻¹. -2 The V2O5 positive electrode sheet is assembled with the negative electrode battery shell, gasket, spring sheet, etc. to form a Zn||V2O5 full cell with model number CR2032.

[0055] S3. Using the assembled Zn||V₂O₅ full cell at a current density of 5 A·g -1 The charge-discharge cycle test was conducted under the conditions of a discharge cutoff voltage of 1.6 V and a charge cutoff voltage of 0.2 V.

[0056] Test results are as follows Figure 3 As shown in (a), the Zn||V2O5 full cell exhibits a discharge specific capacity of up to 116.5 mAh·g after 1000 charge-discharge cycles using L-pyroglutamic acid. -1 .

[0057] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that L-pyroglutamic acid was not added to Comparative Example 3, but everything else is the same.

[0058] A method for preparing a zinc metal battery includes the following steps: S1. At room temperature, add 5.7510 g of zinc sulfate heptahydrate to 7.5 mL of deionized water and stir at 500 rpm for 6 h to prepare an electrolyte containing L-pyroglutamic acid with a concentration of 2 mol / L zinc sulfate (this electrolyte is referred to as Without LPA).

[0059] S2. Using an electrolyte containing 80 μL of 2 mol / L zinc sulfate, a 100 μm thick zinc foil negative electrode (16 μm in diameter), a glass fiber diaphragm, a 12 mm diameter positive electrode with graphite paper as the current collector and V₂O₅ as the positive electrode active material with a loading of 1 mg·cm⁻¹. -2 The V2O5 positive electrode sheet is assembled with the negative electrode battery shell, gasket, spring sheet, etc. to form a Zn||V2O5 full cell with model number CR2032.

[0060] S3. Using the assembled Zn||V₂O₅ full cell at a current density of 5 A·g -1 The charge-discharge cycle test was conducted under the conditions of a discharge cutoff voltage of 1.6 V and a charge cutoff voltage of 0.2 V.

[0061] Test results are as follows Figure 3 As shown in (b), without L-pyroglutamic acid, the discharge specific capacity of the Zn||V2O5 full cell after 1000 charge-discharge cycles is only 69.7 mAh·g. -1 .

[0062] Comparing Example 3 with Comparative Example 3, the L-pyroglutamic acid significantly improves the specific capacity of Zn||V2O5 full cells.

[0063] Example 4 A method for preparing a zinc metal battery includes the following steps: S1. At room temperature, 2.8755 g of zinc sulfate heptahydrate and 0.0648 g of L-pyroglutamic acid were added to 7.5 mL of deionized water and stirred at 500 rpm for 6 h to prepare an electrolyte containing 1 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid (abbreviated as With LPA).

[0064] S2. An electrolyte containing 80 μL of 1 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid is used; a 50 μm thick zinc foil negative electrode (16 μm in diameter) is used; a glass fiber diaphragm is used; and a 12 mm diameter positive electrode with graphite paper as the current collector and V₂O₅ as the positive active material with a loading of 1 mg·cm⁻¹ is used. -2 The V2O5 positive electrode sheet is assembled with the negative electrode battery shell, gasket, spring sheet, etc. to form a Zn||V2O5 full cell with model number CR2032.

[0065] S3. Using the assembled Zn||V₂O₅ full cell at a current density of 5 A·g -1 The charge-discharge cycle test was conducted under the conditions of a discharge cutoff voltage of 1.6 V and a charge cutoff voltage of 0.2 V.

[0066] Test results are as follows Figure 4 As shown, when using an aqueous zinc metal battery electrolyte additive (L-pyroglutamic acid), the Zn||V2O5 full cell exhibits a discharge specific capacity of 43.6 mAh·g after 1500 charge-discharge cycles. -1 .

[0067] Comparative Example 4 The difference between Comparative Example 4 and Example 4 is that Comparative Example 4 uses equimolar amounts of electrolyte additives (L-glutamic acid, monosodium glutamate, L-proline) to replace L-pyroglutamic acid, while all other aspects are the same.

[0068] A method for preparing a zinc metal battery includes the following steps: S1. At room temperature, three equal masses (2.8755 g) of zinc sulfate heptahydrate were added to 7.5 mL of deionized water. Then, 0.0735 g of L-glutamic acid, 0.0856 g of monosodium glutamate (MSG), and 0.0576 g of L-proline were added respectively. The mixture was stirred at 500 rpm for 6 h to prepare electrolytes containing 1 mol / L zinc sulfate and 0.05 mol / L L-glutamic acid, MSG, and L-proline. Samples using this electrolyte were designated "With GAS", "With GASN", and "With FAS", respectively.

[0069] S2. An electrolyte containing 80 μL of 1 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid is used; a 50 μm thick zinc foil negative electrode (16 μm in diameter) is used; a glass fiber diaphragm is used; and a 12 mm diameter positive electrode with graphite paper as the current collector and V₂O₅ as the positive active material with a loading of 1 mg·cm⁻¹ is used. -2 The V2O5 positive electrode sheet is assembled with the negative electrode battery shell, gasket, spring sheet, etc. to form a Zn||V2O5 full cell with model number CR2032.

[0070] S3. Using the assembled Zn||V₂O₅ full cell at a current density of 5 A·g -1 The charge-discharge cycle test was conducted under the conditions of a discharge cutoff voltage of 1.6 V and a charge cutoff voltage of 0.2 V.

[0071] Test results are as follows Figure 4 As shown, without L-pyroglutamic acid, the discharge specific capacity of the Zn||V2O5 full cell after 1500 charge-discharge cycles is only 25.0 mAh·g. -1 26.5 mAh·g -1 15.9 mAh·g -1 .

[0072] Comparing Example 4 with Comparative Example 4, we can conclude that L-pyroglutamic acid has a more significant effect on improving the specific capacity of Zn||V2O5 full cells compared to aqueous zinc metal battery electrolyte additives such as L-glutamic acid, L-glutamic acid, monosodium glutamate, and L-proline.

[0073] Example 5 A method for preparing a zinc metal battery includes the following steps: S1. At room temperature, four equal masses (2.8755 g) of zinc sulfate heptahydrate were added to 7.5 mL of deionized water, followed by the addition of 0 g, 0.0130 g, 0.0259 g, and 0.0648 g of L-pyroglutamic acid, respectively. The mixture was stirred at 500 rpm for 6 h to prepare electrolytes containing 1 mol / L zinc sulfate and 0 mol / L, 0.01 mol / L, 0.02 mol / L, and 0.05 mol / L L-pyroglutamic acid, respectively. Samples using this electrolyte were designated "With 0 LPA", "With 10 LPA", "With 20 LPA", and "With 50 LPA", respectively.

[0074] S2. An electrolyte containing 80 μL of 1 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid is used; a 50 μm thick zinc foil negative electrode (16 mm in diameter) is used; a glass fiber diaphragm is used; a 12 mm diameter positive electrode is used with graphite paper as the current collector and V₂O₅ as the positive electrode active material with a loading of 1 mg·cm⁻¹ is used. -2 The V2O5 positive electrode sheet is assembled with the negative electrode battery shell, gasket, spring sheet, etc. to form a Zn||V2O5 full cell with model number CR2032.

[0075] S3. Using the assembled Zn||V₂O₅ full cell at a current density of 5 A·g -1 The charge-discharge cycle test was conducted under the conditions of a discharge cutoff voltage of 1.6 V and a charge cutoff voltage of 0.2 V.

[0076] Test results are as follows Figure 5 As shown, when using different concentrations (0 mol / L, 0.01 mol / L, 0.02 mol / L, 0.05 mol / L) of aqueous zinc metal battery electrolyte additive (L-pyroglutamic acid), the discharge specific capacity of the Zn||V2O5 full cell after 1500 charge-discharge cycles was 40.8 mAh·g. -1 43.6 mAh·g -1 43.8 mAh·g -1 50.1 mAh·g -1 Compared to before, both have seen some improvement.

[0077] Example 6 Raman spectroscopy is one of the main characterization methods for verifying the effect of electrolyte additives on the proportion of different types of hydrogen bond components in the electrolyte. It includes the following steps: S1. At room temperature, 5.7510 g of zinc sulfate heptahydrate and 0.0648 g of L-pyroglutamic acid were added to 7.5 mL of deionized water and stirred at 500 rpm for 6 h to prepare an electrolyte containing 2 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid (abbreviated as With LPA).

[0078] At room temperature, 5.7510 g of zinc sulfate heptahydrate was added to 7.5 mL of deionized water and stirred at 500 rpm for 6 h to prepare an electrolyte containing 2 mol / L zinc sulfate (this electrolyte is referred to as Without LPA).

[0079] S2. Using a brand-new, clean, and dry pad as a substrate, place it on the plane where the laser spot of the Raman spectrometer is located. Add one drop of electrolyte S1 to the pad (with LPA and without LPA) respectively, and scan the full spectrum with a 532 nm laser.

[0080] S3. Use Origin software to complete the 3000-3800 cm... -1 Peak fitting of hydrogen bond peaks within the range.

[0081] Test results are as follows Figure 6 As shown in (a), Figure 6 As shown in (b), when L-pyroglutamic acid is used, the electrolyte contains 73.1% medium and weak hydrogen bonds and 26.9% strong hydrogen bonds. Without L-pyroglutamic acid, the electrolyte contains 55.1% medium and weak hydrogen bonds and 44.9% strong hydrogen bonds. The use of L-pyroglutamic acid significantly affects the proportion of hydrogen bonds of varying strengths in the electrolyte, suggesting a potential reconstruction of the hydrogen bond network.

[0082] Example 7 Creating an electrolyte environment with a lower pH is a simple and effective method to inhibit corrosion on the surface of zinc anodes. Observing the accumulation of basic zinc sulfate, a corrosion product, on the surface of zinc electrodes after soaking in an electrolyte containing L-pyroglutamic acid as an electrolyte additive for several days (e.g., 3 days) is one of the main test methods for evaluating the inhibitory effect of electrolyte additives on the corrosion reaction on the surface of zinc anodes.

[0083] S1. At room temperature, 5.7510 g of zinc sulfate heptahydrate and 0.0648 g of L-pyroglutamic acid were added to 7.5 mL of deionized water and stirred at 500 rpm for 6 h to prepare an electrolyte containing 2 mol / L zinc sulfate and 0.05 mol / L L-pyroglutamic acid (abbreviated as With LPA).

[0084] At room temperature, 5.7510 g of zinc sulfate heptahydrate was added to 7.5 mL of deionized water and stirred at 500 rpm for 6 h to prepare an electrolyte containing 2 mol / L zinc sulfate (this electrolyte is referred to as Without LPA).

[0085] S2. Take a clean, dry, and polished zinc foil negative electrode and immerse it completely in 2 mL of electrolyte in S1 (with LPA and without LPA) for 3 days.

[0086] S3. After 3 days, remove the product and allow it to dry completely. Then, observe the surface under a field emission scanning electron microscope.

[0087] Test results are as follows Figure 7 As shown in (a), when L-pyroglutamic acid is used, the hexagonal basic zinc sulfate component on the zinc foil negative electrode surface is almost unobservable, meaning its formation is significantly suppressed. When L-pyroglutamic acid is not used, the hexagonal basic zinc sulfate component on the zinc foil negative electrode surface is very abundant, indicating that the corrosion reaction occurs quite violently.

[0088] The additive L-pyroglutamic acid has a strong inhibitory effect on the corrosion reaction on the zinc anode surface.

[0089] Compared with existing technologies, the Zn||Zn symmetric cell assembled in this application shows, after cycle stability testing, that at 2 mA·cm⁻¹, -2 It can operate stably for more than 5000 hours at a current density of [value missing]; the assembled Zn||Cu half-cell can operate stably at 1 mA·cm[value missing]. -2 It can operate stably for more than 250 cycles at a current density of [value missing], with an average coulombic efficiency of up to 99.66%; the assembled Zn||V₂O₅ full cell [value missing] at 5 A·g [value missing] -1 After operating stably for 1000 cycles at a current density, its specific capacity remains as high as 116.5 mAh·g. -1 Therefore, using the aqueous zinc metal battery electrolyte provided in this application can significantly improve the cycle performance of aqueous zinc metal batteries, providing a good approach for the preparation of high-performance aqueous zinc metal batteries.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application 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 this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. An aqueous zinc metal battery electrolyte, characterized in that, It includes L-pyroglutamic acid, zinc salt and water, wherein the concentration of L-pyroglutamic acid in the aqueous zinc metal battery electrolyte is 0.01~0.5 mol / L.

2. The aqueous zinc metal battery electrolyte according to claim 1, characterized in that, The concentration of L-pyroglutamic acid in the aqueous zinc metal battery electrolyte is 0.02~0.05 mol / L.

3. The aqueous zinc metal battery electrolyte according to claim 1, characterized in that, The zinc salt includes at least one of zinc sulfate, zinc chloride, zinc bromide, zinc nitrate, zinc acetate, and zinc trifluoromethanesulfonate.

4. The aqueous zinc metal battery electrolyte according to claim 1, characterized in that, The concentration of the zinc salt in the aqueous zinc metal battery electrolyte is 1~3 mol / L.

5. The aqueous zinc metal battery electrolyte according to claim 1, characterized in that, The zinc salt includes zinc sulfate.

6. The aqueous zinc metal battery electrolyte according to claim 1, characterized in that, The concentration of L-pyroglutamic acid in the aqueous zinc metal battery electrolyte is 0.05 mol / L; the concentration of zinc salt in the aqueous zinc metal battery electrolyte is 2 mol / L.

7. A zinc metal battery, characterized in that, Includes the aqueous zinc metal battery electrolyte as described in any one of claims 1 to 6.

8. The zinc metal battery according to claim 7, characterized in that, It also includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode; the negative electrode is zinc metal, and the positive electrode includes a positive current collector and a positive active material layer located on at least one surface of the positive current collector, the positive active material layer including a positive active material, the positive active material including an intercalation compound.

9. The zinc metal battery according to claim 8, characterized in that, The zinc metal includes at least one of zinc plate, zinc sheet, zinc foil, and zinc foam; the intercalation compound includes at least one of manganese-based materials, vanadium-based materials, and Prussian blue analogues; and the diaphragm includes a glass fiber diaphragm.

10. The zinc metal battery according to claim 8, characterized in that, The manganese-based material includes MnO2, the vanadium-based material includes V2O5, and the Prussian blue analogue includes Fe4[Fe(CN)6]3.

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