Wide voltage window electrolyte for aqueous zinc-based batteries and preparation method and application thereof

Abstract

The application discloses a wide-voltage-window electrolyte for a water-based zinc-based battery and a preparation method and application thereof, and relates to the technical field of batteries.The wide-voltage-window electrolyte for the water-based zinc-based battery comprises a solute, a solvent, a first functional additive and a second functional additive, wherein the solute is at least one of zinc sulfate, zinc acetate, zinc triflate and zinc bis(trifluoromethylsulfonyl)imide, the solvent is a mixture of water and ethanedinitrile, the first functional additive is at least one of potassium acetate and ammonium acetate, and the second functional additive is fluoroethylene carbonate.By precisely controlling the volume ratio of water to ethanedinitrile in the solvent, adding the first functional additive and the second functional additive, a wide-voltage-window of 0.1-3.1 V is obtained, and the zinc ion conductivity at 25 DEG C is ensured to be greater than 5.0 mS / cm, thereby solving the technical pain point that the voltage window and the ion conductivity are difficult to be considered in the prior art, and the charge-discharge stability of the zinc-iodine battery is improved.

Description

Technical Field

[0001] This invention belongs to the field of aqueous zinc-based battery technology, specifically relating to a wide voltage window electrolyte for aqueous zinc-based batteries, its preparation method, and its application. Background Technology

[0002] Voltage window is one of the key parameters that determine battery energy density. Traditional aqueous zinc-based batteries have a low hydrogen and oxygen evolution potential in aqueous electrolytes, so their electrochemical stable voltage window is usually limited to 0.8V-1.65V. This narrow window greatly limits the selection of high-potential cathode materials and cannot meet the needs of grid-scale energy storage, high-end portable electronic devices and other high-energy-density energy storage scenarios.

[0003] Extensive research has been conducted in existing technologies to broaden the voltage window of aqueous electrolytes. Widely used strategies include employing high-concentration zinc salt solutions or adding inorganic additives. These strategies aim to suppress side reactions by reducing water molecule activity and increasing the overpotential of the hydrogen and oxygen evolution reactions, thereby broadening the voltage window. While using high-concentration zinc salt solutions raises the upper limit of the voltage window to approximately 2.6V, it also results in a significant increase in the viscosity of the aqueous electrolyte and a decrease in ionic conductivity. This not only impairs the battery's rate performance but also significantly increases manufacturing costs due to the large-scale use of high-purity salt raw materials. Adding inorganic additives can inhibit water decomposition to some extent, raising the upper limit of the voltage window to around 2.1V. However, this also increases the viscosity of the aqueous electrolyte and slows down ion transport kinetics, leading to poorer battery cycle stability and low-temperature adaptability, making it difficult to meet practical application requirements. It is evident that existing technologies generally face a "stability-kinetics" dilemma, meaning that while widening the voltage window inevitably sacrifices the ion conduction performance of aqueous electrolytes, and cannot fundamentally solve the side reactions such as electrode corrosion and dendrite growth caused by water molecules, thus hindering the industrialization of aqueous zinc-based batteries. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a wide voltage window electrolyte for aqueous zinc-based batteries.

[0005] Another object of the present invention is to provide a method for preparing the above-described wide voltage window electrolyte for aqueous zinc-based batteries.

[0006] Another object of the present invention is to provide the application of the above-mentioned wide voltage window electrolyte for aqueous zinc-based batteries as an electrolyte.

[0007] The objective of this invention is achieved through the following technical solution.

[0008] A wide voltage window electrolyte for aqueous zinc-based batteries comprises: a solute, a solvent, a first functional additive, and a second functional additive. The solute is at least one of zinc sulfate, zinc acetate, zinc trifluoromethanesulfonate, and zinc bis(trifluoromethanesulfonyl)imide. The solvent is a mixture of water and oxonium. The first functional additive is at least one of potassium acetate and ammonium acetate. The second functional additive is fluoroethylene carbonate. The molar ratio of the solute to the volume fraction of the solvent is (0.5~5):1. The molar ratio is in mol, and the volume fraction is in L. The ratio of the solute, the first functional additive, and the second functional additive, by molar ratio, is (0.5~5):(0.1~0.8):(0.01~0.1).

[0009] In the above technical solution, the preferred ratio of the molar amount of solute to the volume fraction of solvent is (1~3):1, where the molar amount is in mol and the volume fraction is in L; the preferred ratio of solute, first functional additive and second functional additive is (1~3):(0.1~0.8):(0.01~0.1) based on the molar amount.

[0010] In the above technical solution, the electrolyte with a wide voltage window for aqueous zinc-based batteries has an ionic conductivity (zinc ion conductivity) of >5.0 mS / cm at 25℃, and the widest voltage window is 0.1~3.1V.

[0011] In the above technical solution, the volume fraction of ethylene nitrile in the solvent is 10~40%.

[0012] A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries includes the following steps:

[0013] Step 1: Mix the solute and solvent until homogeneous to obtain a first mixed solution, wherein the solute is at least one of zinc sulfate, zinc acetate, zinc trifluoromethanesulfonate and zinc bis(trifluoromethanesulfonyl)imide, the solvent is a mixture of water and oxonium, and the ratio of the molar fraction of the solute to the volume fraction of the solvent is (0.5~5):1, the unit of molar fraction is mol, and the unit of volume fraction is L;

[0014] In step 1, the volume fraction of ethylene nitrile in the solvent is 10-40%, preferably 20-30%.

[0015] In step 1, the method for obtaining the solvent includes: mixing water and oxonium at 23~27℃ and stirring at 300~500 r / min for 15~30 min until homogeneous, to obtain a transparent solvent.

[0016] In step 1, the solute and solvent are mixed and stirred at 23~27℃ at a speed of 300~500r / min until homogeneous to obtain the first mixed solution.

[0017] Step 2: Mix the first functional additive and the first mixed solution until homogeneous to obtain a second mixed solution, wherein the pH value of the second mixed solution is 5.0~7.0, and the first functional additive is at least one of potassium acetate and ammonium acetate;

[0018] In step 2, the first functional additive and the first mixed solution are mixed and stirred at 23~27℃ at a speed of 200~300r / min until homogeneous to obtain the second mixed solution.

[0019] Step 3: Mix the second functional additive and the second mixed solution until homogeneous to obtain a wide voltage window electrolyte for aqueous zinc-based batteries, wherein the second functional additive is fluoroethylene carbonate;

[0020] Based on the molar amounts, the ratio of solute, first functional additive, and second functional additive in the first mixed solution is (0.5~5):(0.1~0.8):(0.01~0.1).

[0021] In step 3, the second functional additive and the second mixed solution are mixed and stirred at 23~27℃ at a speed of 200~300r / min until homogeneous, to obtain a wide voltage window electrolyte for aqueous zinc-based batteries.

[0022] The above-mentioned wide voltage window electrolytes used in aqueous zinc-based batteries are applied in zinc-iodine batteries.

[0023] The above-mentioned wide voltage window electrolyte is used as an electrolyte in aqueous zinc-based batteries.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. This invention achieves a wide voltage window of 0.1~3.1V by precisely controlling the volume ratio of water to oxonium in the solvent and adding a first functional additive and a second functional additive, while ensuring a zinc ion conductivity >5.0mS / cm at 25℃. This solves the technical pain point of the prior art where it is difficult to balance voltage window and ion conductivity, thereby improving the charge and discharge stability of zinc-iodine batteries. Specifically, by adding the first functional additive (potassium acetate or ammonium acetate) and precisely adjusting the pH value to 5.0-7.0, the corrosion reaction of the negative electrode (zinc sheet) is effectively suppressed. The second functional additive (fluoroethylene carbonate) can form a stable SEI film on the surface of the zinc sheet (negative electrode), further enhancing the stability of the electrode interface and blocking the occurrence of side reactions. This solves the key problems of easy corrosion of zinc sheet (negative electrode) and short cycle life of zinc-iodine batteries in the prior art.

[0026] 2. The preparation process of this invention is stable and controllable, and the product has uniform properties; the solute can be a variety of zinc salts such as zinc sulfate and zinc acetate, and it has wide applicability.

[0027] 3. The raw materials used in this invention are all conventional and readily available chemicals. The preparation process does not require complex and high-end equipment, is simple and efficient, and the amount of each raw material can be precisely controlled according to the target requirements, avoiding waste of raw materials. It is suitable for large-scale production and has significant prospects for industrial application. Attached Figure Description

[0028] Figure 1 The LSV diagrams are obtained based on the wide voltage window electrolytes for aqueous zinc-based batteries in Examples 1-4, where (b) is a partial enlarged view of (a).

[0029] Figure 2 This is a bar chart showing the ionic conductivity of the wide voltage window electrolytes used in aqueous zinc-based batteries according to Examples 1-4.

[0030] Figure 3 The CV curve is shown for the wide voltage window electrolyte prepared in Example 1 for use in aqueous zinc-based batteries.

[0031] Figure 4 The charge-discharge diagram of the zinc-iodine battery prepared from the wide voltage window electrolyte for aqueous zinc-based batteries in Example 1 at a current density of 1.0 C is shown.

[0032] Figure 5 The charge-discharge diagram of the zinc-iodine battery prepared from the wide voltage window electrolyte for aqueous zinc-based batteries in Example 2 at a current density of 1.0 C is shown.

[0033] Figure 6 The charge-discharge diagram of the zinc-iodine battery prepared from the wide voltage window electrolyte for aqueous zinc-based batteries in Example 3 at a current density of 1.0 C is shown.

[0034] Figure 7 The charge-discharge diagram of the zinc-iodine battery prepared from the wide voltage window electrolyte for aqueous zinc-based batteries in Example 4 at a current density of 1.0 C is shown.

[0035] Figure 8 The graph shows the cycling performance of a zinc-iodine battery prepared from the wide voltage window electrolyte of Example 1 for aqueous zinc-based batteries at a current density of 1.0 C.

[0036] Figure 9 The graph shows the cycling performance of a zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries in Example 2 at a current density of 1.0 C.

[0037] Figure 10 The graph shows the cycling performance of a zinc-iodine battery prepared from the wide voltage window electrolyte of Example 3 for aqueous zinc-based batteries at a current density of 1.0 C.

[0038] Figure 11 The graph shows the cycling performance of a zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries described in Example 4 at a current density of 1.0 C.

[0039] Figure 12 The charge-discharge diagram of the zinc-iodine battery prepared from the wide voltage window electrolyte of Comparative Example 1 for aqueous zinc-based batteries at a current density of 1.0 C is shown.

[0040] Figure 13 The charge-discharge diagram of the zinc-iodine battery prepared from the wide voltage window electrolyte for aqueous zinc-based batteries in Comparative Example 2 is shown at a current density of 1.0 C.

[0041] Figure 14 The charge-discharge diagram of the zinc-iodine battery prepared from the wide voltage window electrolyte of Comparative Example 3 for aqueous zinc-based batteries at a current density of 1.0 C is shown.

[0042] Figure 15 The charge-discharge diagram of the zinc-iodine battery prepared from the wide voltage window electrolyte of Comparative Example 4 for aqueous zinc-based batteries at a current density of 1.0 C is shown.

[0043] Figure 16 The charge-discharge diagram of the zinc-iodine battery prepared from the wide voltage window electrolyte of Comparative Example 5 for aqueous zinc-based batteries at a current density of 1.0 C is shown.

[0044] Figure 17 This is a graph showing the long-term cycling performance of a zinc-zinc symmetric battery prepared based on the wide voltage window electrolyte for aqueous zinc-based batteries in Example 1.

[0045] Figure 18 SEM images of the negative electrode sheet before and after the long-term cycling performance test are shown, where a is the SEM image of the negative electrode sheet before the long-term cycling performance test and b is the SEM image of the negative electrode sheet after the long-term cycling performance test.

[0046] Figure 19 The rate performance graph shows the zinc-iodine battery prepared from the wide voltage window electrolyte for aqueous zinc-based batteries in Example 1.

[0047] Figure 20 The graph shows the cycling performance of the zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries in Comparative Example 1 at a current density of 1.0 C.

[0048] Figure 21 The graph shows the cycling performance of the zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries in Comparative Example 2 at a current density of 1.0 C.

[0049] Figure 22The graph shows the cycling performance of the zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries in Comparative Example 3 at a current density of 1.0 C.

[0050] Figure 23 The graph shows the cycling performance of the zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries in Comparative Example 4 at a current density of 1.0 C.

[0051] Figure 24 The graph shows the cycling performance of a zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries of Comparative Example 5 at a current density of 1.0 C. Detailed Implementation

[0052] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0053] The raw material information involved in the following examples and comparative examples is as follows:

[0054] Zinc sulfate, zinc acetate, zinc trifluoromethanesulfonate, zinc bis(trifluoromethanesulfonyl)imide, butyronitrile and propionitrile were all purchased from Aladdin Reagent Network. Oxygenonitrile, potassium acetate and fluoroethylene carbonate were all purchased from Maclean Reagent Network. Active porous carbon powder was purchased from Jinan Shengquan Group Co., Ltd., model ZLD-3.

[0055] Fluoroethylene carbonate must be dehydrated and dried before use to ensure that the moisture content is ≤0.05wt%.

[0056] In the following examples and comparative examples, the water used is deionized water.

[0057] The instrument information involved in the following embodiments and comparative examples is as follows:

[0058] The electrochemical workstation was purchased from Shanghai Chenhua Instrument Co., Ltd.

[0059] The ion conductivity meter was purchased from Mettler Toledo International Trading (Shanghai) Co., Ltd., model SevenDirectSD30.

[0060] The cycle performance and rate performance of the zinc-iodine battery were tested using the Land CT2001A testing system. The ambient temperature was 25℃ and the voltage range was 0.8V to 1.6V.

[0061] In the cycle performance graph, the horizontal axis "cycles" represents the number of cycles, the left vertical axis "specific capacity" represents the discharge specific capacity, and the right vertical axis "efficiency" represents the coulombic efficiency.

[0062] In the rate performance graph, the horizontal axis "Cycles" represents the number of cycles, the left vertical axis "Capacity" represents the discharge specific capacity, and the right vertical axis "Efficiency" represents the coulombic efficiency.

[0063] Example 1

[0064] A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries includes the following steps:

[0065] Step 1: Mix the solute and solvent, and stir at 400 r / min for 45 min at 25°C until homogeneous to obtain a first mixed solution. The solute is zinc trifluoromethanesulfonate, and the solvent is a mixture of water and oxonium. The volume fraction of oxonium in the solvent is 30%. The method for obtaining the solvent includes: placing water and oxonium in a dry beaker, turning on a magnetic stirrer, and stirring at 400 r / min for 20 min at 25°C until homogeneous to obtain a transparent solvent. The ratio of the molar fraction of the solute to the volume fraction of the solvent is 3:1. The unit of molar fraction is mol, and the unit of volume fraction is L.

[0066] Step 2: Mix the first functional additive and the first mixed solution, and stir at 250 r / min for 30 min at 25℃ until homogeneous to obtain the second mixed solution. The pH value of the second mixed solution is 6.0, and the first functional additive is potassium acetate.

[0067] Step 3: Mix the second functional additive and the second mixed solution, and stir at 25°C and 250 r / min for 18 min until homogeneous to obtain a wide voltage window electrolyte (pH value of 6.0) for aqueous zinc-based batteries. The second functional additive is fluoroethylene carbonate.

[0068] Based on the molar amounts of substances, the ratio of solute, first functional additive, and second functional additive in the first mixed solution is 3:0.1:0.05.

[0069] In the wide voltage window electrolyte for aqueous zinc-based batteries prepared in Example 1, the concentration of the solute is about 3 mol / L, the concentration of the first functional additive is about 0.1 mol / L, and the concentration of the second functional additive is about 0.05 mol / L.

[0070] Example 2

[0071] A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries includes the following steps:

[0072] Step 1: Mix the solute and solvent, and stir at 400 r / min for 45 min at 25°C until homogeneous to obtain a first mixed solution. The solute is zinc bis(trifluoromethanesulfonyl)imide, and the solvent is a mixture of water and oxonium. The volume fraction of oxonium in the solvent is 30%. The method for obtaining the solvent is the same as in Example 1. The ratio of the molar amount of the solute to the volume fraction of the solvent is 3:1. The unit of molar amount is mol, and the unit of volume fraction is L.

[0073] Step 2: Mix the first functional additive and the first mixed solution, and stir at 25°C and 250 r / min for 30 min until homogeneous to obtain the second mixed solution. The pH value of the second mixed solution is 5.8, and the first functional additive is potassium acetate.

[0074] Step 3: Mix the second functional additive and the second mixed solution, and stir at 25°C and 250 r / min for 18 min until homogeneous to obtain a wide voltage window electrolyte (pH value 5.8) for aqueous zinc-based batteries. The second functional additive is fluoroethylene carbonate.

[0075] Based on the molar amounts of substances, the ratio of solute, first functional additive, and second functional additive in the first mixed solution is 3:0.1:0.05.

[0076] In the wide voltage window electrolyte for aqueous zinc-based batteries prepared in Example 2, the concentration of the solute is approximately 3.0 mol / L, the concentration of the first functional additive is approximately 0.1 mol / L, and the concentration of the second functional additive is approximately 0.05 mol / L.

[0077] Example 3

[0078] A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries includes the following steps:

[0079] Step 1: Mix the solute and solvent, and stir at 400 r / min for 45 min at 25°C until homogeneous to obtain a first mixed solution. The solute is zinc sulfate, and the solvent is a mixture of water and oxonium. The volume fraction of oxonium in the solvent is 30%. The method for obtaining the solvent is the same as in Example 1. The ratio of the molar amount of solute to the volume fraction of the solvent is 3:1. The unit of molar amount is mol, and the unit of volume fraction is L.

[0080] Step 2: Mix the first functional additive and the first mixed solution, and stir at 25°C and 250 r / min for 30 min until homogeneous to obtain the second mixed solution. The pH value of the second mixed solution is 5.2, and the first functional additive is potassium acetate.

[0081] Step 3: Mix the second functional additive and the second mixed solution, and stir at 25°C and 250 r / min for 18 min until homogeneous to obtain a wide voltage window electrolyte (pH value of 5.2) for aqueous zinc-based batteries. The second functional additive is fluoroethylene carbonate.

[0082] Based on the molar amounts of substances, the ratio of solute, first functional additive, and second functional additive in the first mixed solution is 3:0.5:0.05.

[0083] In the wide voltage window electrolyte for aqueous zinc-based batteries prepared in Example 3, the concentration of the solute is approximately 3.0 mol / L, the concentration of the first functional additive is approximately 0.5 mol / L, and the concentration of the second functional additive is approximately 0.05 mol / L.

[0084] Example 4

[0085] A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries includes the following steps:

[0086] Step 1: Mix the solute and solvent, and stir at 400 r / min for 45 min at 25°C until homogeneous to obtain a first mixed solution. The solute is zinc acetate, and the solvent is a mixture of water and oxonium. The volume fraction of oxonium in the solvent is 30%. The method for obtaining the solvent is the same as in Example 1. The ratio of the molar amount of the solute to the volume fraction of the solvent is 3:1. The unit of molar amount is mol, and the unit of volume fraction is L.

[0087] Step 2: Mix the first functional additive and the first mixed solution, and stir at 250 r / min for 30 min at 25℃ until homogeneous to obtain the second mixed solution. The pH value of the second mixed solution is 6.8, and the first functional additive is potassium acetate.

[0088] Step 3: Mix the second functional additive and the second mixed solution, and stir at 25°C and 250 r / min for 18 min until homogeneous to obtain a wide voltage window electrolyte (pH value 6.8) for aqueous zinc-based batteries. The second functional additive is fluoroethylene carbonate.

[0089] Based on the molar amounts of substances, the ratio of solute, first functional additive, and second functional additive in the first mixed solution is 3:0.1:0.05.

[0090] In the wide voltage window electrolyte for aqueous zinc-based batteries prepared in Example 4, the concentration of the solute was approximately 3.0 mol / L, the concentration of the first functional additive was approximately 0.1 mol / L, and the concentration of the second functional additive was approximately 0.05 mol / L.

[0091] Comparative Example 1

[0092] A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries is basically the same as that in Example 1, except that "ethylenedionitrile" is replaced with "propionitrile".

[0093] Comparative Example 2

[0094] A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries is basically the same as that in Example 1, except that "ethylene nitrile" is replaced with "butyronitrile".

[0095] Comparative Example 3

[0096] A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries is basically the same as that in Example 3, except that the first functional additive is not added.

[0097] Comparative Example 4

[0098] A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries is basically the same as that in Example 3, except that no second functional additive is added.

[0099] Comparative Example 5

[0100] A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries includes: mixing a solute and a solvent, stirring at 25°C and 400 r / min for 45 min until homogeneous, to obtain a wide voltage window electrolyte (pH 6.1) for aqueous zinc-based batteries. The solute is zinc trifluoromethanesulfonate, and the solvent is a mixture of water and propionitrile, with a volume fraction of propionitrile of 30%. The method for obtaining the solvent includes: placing water and propionitrile in a dry beaker, turning on a magnetic stirrer, and stirring at 25°C and 400 r / min for 20 min until homogeneous, to obtain a transparent solvent. The molar ratio of the solute to the volume fraction of the solvent is 3:1, with the molar ratio expressed in mol and the volume fraction in L.

[0101] Under constant temperature conditions of 25℃, the voltage window of the electrolyte was tested using a three-electrode system. The working electrode of the three-electrode system was a stainless steel sheet, the reference electrode was a zinc sheet, and the auxiliary electrode was a platinum sheet. This three-electrode system was placed in an electrolytic cell, and the electrolyte was injected into the cell. An electrochemical workstation was connected, and the test was performed using linear sweep voltammetry (LSV) (scan rate set to 5 mV / s). The LSV plot was obtained. The electrolyte was one of the wide-voltage-window electrolytes for aqueous zinc-based batteries prepared in Examples 1-4 and Comparative Examples 1-5. The wide-voltage-window electrolytes for aqueous zinc-based batteries prepared in Examples 1-4 were used to obtain the following results: Figure 1 The LSV diagram shown is as follows. Figure 1 (b) is Figure 1A magnified view of the 2.0~3.4V range in (a). (From...) Figure 1 As shown in (b), the voltage window of the wide-voltage-window electrolyte for aqueous zinc-based batteries prepared in Example 1 is 0.1–3.1 V; the voltage window of the wide-voltage-window electrolyte for aqueous zinc-based batteries prepared in Example 2 is 0.1–2.9 V; the voltage window of the wide-voltage-window electrolyte for aqueous zinc-based batteries prepared in Example 3 is 0.1–2.75 V; the voltage window of the wide-voltage-window electrolyte for aqueous zinc-based batteries prepared in Example 4 is 0.1–2.6 V; and the voltage windows of the wide-voltage-window electrolytes for aqueous zinc-based batteries prepared in Examples 1–4 and Comparative Examples 1–5 are shown in Table 1. Figure 1 As shown in Table 1, the wide voltage window electrolyte prepared in Example 1 for use in aqueous zinc-based batteries has the widest voltage window, indicating that it has the best reliability and stability.

[0102] The ionic conductivity of the electrolyte at 25°C was measured using an ionic conductivity meter. The electrolyte was one of the wide-voltage-window electrolytes for aqueous zinc-based batteries prepared in Examples 1-4 and Comparative Examples 1-5. Specifically, the wide-voltage-window electrolytes for aqueous zinc-based batteries prepared in Examples 1-4 were used to obtain... Figure 2 The trend graph of ionic conductivity shown is from... Figure 2 It can be seen that the wide-voltage-window electrolytes prepared in Examples 1-4 for use in aqueous zinc-based batteries all exhibit good ionic conductivity. Among them, the wide-voltage-window electrolyte prepared in Example 1 has the highest ionic conductivity, reaching 6.2 mS / cm. The ionic conductivity (at 25°C) of the wide-voltage-window electrolytes prepared in Examples 1-4 and Comparative Examples 1-5 for use in aqueous zinc-based batteries is shown in Table 1. It is evident that the type of solute has a certain influence on ionic conductivity; when zinc trifluoromethanesulfonate is used as the solute, the ion migration ability of the wide-voltage-window electrolyte for use in aqueous zinc-based batteries is stronger.

[0103] Cyclic voltammetry (CV) tests were conducted using a three-electrode system at a constant temperature of 25°C. The system employed a stainless steel sheet as the working electrode, a zinc sheet as the counter electrode (i.e., zinc electrode), and a saturated calomel electrode (SCE) as the reference electrode. This three-electrode system was placed in an electrolytic cell, and an electrolyte was injected. An electrochemical workstation was connected, and the scan voltage range was set to -0.5 V to 3.5 V, with a scan rate of 0.1 mV / s. The electrolyte was the wide-voltage-window electrolyte prepared in Example 1 for use in aqueous zinc-based batteries. The test results are as follows: Figure 3 As shown, by Figure 3It can be clearly observed that the current density begins to increase when the voltage is above 2.5 V. This is because water in the electrolyte begins to decompose and produce hydrogen. Therefore, it can be determined that the wide voltage window electrolyte prepared in Example 1 for use in aqueous zinc-based batteries has good electrochemical stability below 2.5 V (the obvious redox peaks in the 0~0.5V voltage range are due to the reversible deposition / dissolution process of zinc ions on the zinc electrode surface, not water decomposition).

[0104] A zinc-iodine battery includes: a positive electrode, a separator, an electrolyte, and a negative electrode (zinc sheet). The separator is a glass fiber membrane (Whatman) with a diameter of 19 mm. The electrolyte is one of the wide voltage window electrolytes for aqueous zinc-based batteries prepared in Examples 1-4 and Comparative Examples 1-5 (using the wide voltage window electrolyte for aqueous zinc-based batteries as the electrolyte). Corresponding zinc-iodine batteries (CR2032 button cells) are obtained according to the wide voltage window electrolytes for aqueous zinc-based batteries prepared in Examples 1-4 and Comparative Examples 1-5. The method for preparing the positive electrode sheet includes: adding carboxymethyl cellulose (CMC) to deionized water and stirring evenly; then adding the positive electrode material and acetylene black (the positive electrode material and acetylene black need to be mixed and ground evenly before being added), stirring until uniform; finally adding styrene-butadiene rubber (SBR) emulsion (the content of styrene-butadiene rubber in the SBR emulsion is 45wt%) to obtain the electrode slurry (by mass, the ratio of positive electrode material, acetylene black, carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR) emulsion and deionized water is 8:1:0.5:0.5:15); uniformly coating the electrode slurry onto titanium foil using a coating machine (coating thickness is 150μm, the width of the titanium foil is 10cm and the length is 10cm); drying in a vacuum drying oven at 80℃ for 12h; then cutting it into round pieces with a diameter of 16mm using a slicing machine and pressing it with a pressing machine to obtain the positive electrode sheet. The method for preparing cathode materials includes: taking 1g of active porous carbon powder (specific surface area ≥1500m²) 2 (g) and 1g of elemental iodine were placed in a reaction vessel and mixed until homogeneous. The reaction vessel was then placed in a vacuum drying oven at 60°C for 12 hours to obtain the positive electrode material.

[0105] At a current density of 1C, a zinc-iodine battery prepared using the wide-voltage-window electrolyte of Example 1 for aqueous zinc-based batteries was subjected to charge-discharge tests. The charge-discharge data from the third cycle (the first two cycles were for battery activation) were selected, and the results are as follows: Figure 4 The charge-discharge diagrams are shown below. Charge-discharge tests were performed on the zinc-iodine battery prepared using the wide-voltage-window electrolyte for aqueous zinc-based batteries described in Example 2. The charge-discharge data from the third cycle (the first two cycles represent the battery activation process) were selected, and the results are shown below. Figure 5The charge-discharge diagrams are shown below. Charge-discharge tests were performed on the zinc-iodine battery prepared using the wide-voltage-window electrolyte for aqueous zinc-based batteries described in Example 3. The charge-discharge data from the third cycle (the first two cycles represent the battery activation process) were selected, and the results are shown below. Figure 6 The charge-discharge diagrams are shown below. Charge-discharge tests were performed on the zinc-iodine battery prepared using the wide-voltage-window electrolyte for aqueous zinc-based batteries described in Example 4. The charge-discharge data from the third cycle (the first two cycles represent the battery activation process) were selected, and the results are shown below. Figure 7 The charge / discharge diagram is shown.

[0106] The zinc-iodine battery prepared using the wide-voltage-window electrolyte of Example 1 for aqueous zinc-based batteries was subjected to cycle performance testing at a current density of 1.0 C. The test results are as follows: Figure 8 As shown; at a current density of 1.0 C, the zinc-iodine battery prepared from the wide voltage window electrolyte of Example 2 for aqueous zinc-based batteries was subjected to cycle performance testing, and the test results are as follows. Figure 9 As shown; at a current density of 1.0 C, the zinc-iodine battery prepared from the wide voltage window electrolyte for aqueous zinc-based batteries of Example 3 was subjected to cycle performance testing, and the test results are as follows. Figure 10 As shown; at a current density of 1.0 C, the zinc-iodine battery prepared from the wide voltage window electrolyte of Example 4 for aqueous zinc-based batteries was subjected to cycle performance testing, and the test results are as follows. Figure 11 As shown in Table 2, the cycling performance of zinc-iodine batteries prepared from the wide voltage window electrolytes for aqueous zinc-based batteries described in Examples 1-4 at a current density of 1.0 C is shown in Table 2.

[0107] At a current density of 1C, a zinc-iodine battery prepared using the wide-voltage-window electrolyte of Comparative Example 1 for aqueous zinc-based batteries was subjected to charge-discharge tests. The charge-discharge data from the third cycle (the first two cycles represent the battery activation process) were selected, and the results are as follows: Figure 12 The charge-discharge diagrams are shown below. Charge-discharge tests were conducted on the zinc-iodine battery prepared using the wide-voltage-window electrolyte for aqueous zinc-based batteries (Comparative Example 2). The charge-discharge data from the third cycle (the first two cycles represent the battery activation process) were selected, and the results are shown below. Figure 13 The charge-discharge diagrams are shown below. Charge-discharge tests were conducted on the zinc-iodine battery prepared using the wide-voltage-window electrolyte for aqueous zinc-based batteries (Comparative Example 3). The charge-discharge data from the third cycle (the first two cycles represent the battery activation process) were selected, and the results are shown below. Figure 14 The charge-discharge diagrams are shown below. Charge-discharge tests were conducted on the zinc-iodine battery prepared using the wide-voltage-window electrolyte for aqueous zinc-based batteries (Comparative Example 4). The charge-discharge data from the third cycle (the first two cycles represent the battery activation process) were selected, and the results are shown below. Figure 15The charge-discharge diagrams are shown below. Charge-discharge tests were conducted on a zinc-iodine battery prepared using the wide-voltage-window electrolyte for aqueous zinc-based batteries (Comparative Example 5). The charge-discharge data from the third cycle (the first two cycles represent the battery activation process) were selected, and the results are shown below. Figure 16 The charge / discharge diagram is shown.

[0108] Table 3 shows the cycle performance of zinc-iodine batteries prepared using the wide-voltage-window electrolytes for aqueous zinc-based batteries from Comparative Examples 1-2 at a current density of 1.0 C. Table 4 shows the cycle performance of zinc-iodine batteries prepared using the wide-voltage-window electrolytes for aqueous zinc-based batteries from Comparative Examples 3-5 at a current density of 1.0 C.

[0109] Discharge tests were conducted on the zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries described in Example 1 at different current densities, and the results were as follows: Figure 19 The rate performance diagram is shown. It illustrates 10 cycles at each current density, with one discharge specific capacity obtained per cycle. The current density increases from 0.1C, 0.5C, 1C, 2C, 5C to 10C, then sequentially decreases back to 5C, 2C, 1C, 0.5C, and 0.1C. Figure 19 It can be seen that the discharge specific capacity (average value) corresponding to the current density increasing from 0.1C, 0.5C, 1C, 2C, 5C to 10C, and then decreasing back to 5C, 2C, 1C, 0.5C, and 0.1C are 262.3 mAh / g, 254.5 mAh / g, 225.7 mAh / g, 203.9 mAh / g, 195.5 mAh / g, 156.3 mAh / g, 193.7 mAh / g, 200.2 mAh / g, 219.8 mAh / g, 249.1 mAh / g, and 258.6 mAh / g, respectively.

[0110] The zinc-iodine battery prepared using the wide-voltage-window electrolyte of Comparative Example 1 for aqueous zinc-based batteries was subjected to cycle performance testing at a current density of 1.0 C. The test results are as follows: Figure 20 As shown; the cycle performance of the zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries of Comparative Example 2 was tested, and the test results are as follows. Figure 21 As shown; the cycle performance of the zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries of Comparative Example 3 was tested, and the test results are as follows. Figure 22 As shown; the cycle performance of the zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries of Comparative Example 4 was tested, and the test results are as follows. Figure 23 As shown; the cycle performance of the zinc-iodine battery prepared using the wide voltage window electrolyte for aqueous zinc-based batteries of Comparative Example 5 was tested, and the test results are as follows. Figure 24 As shown.

[0111] A zinc-zinc symmetric battery (CR2032 type coin cell) was assembled using 110 μm thick zinc sheets as positive and negative electrodes, a glass fiber membrane (Whatman) as a separator, and the wide voltage window electrolyte prepared in Example 1 for aqueous zinc-based batteries as the electrolyte. Specifically, 150 μL of electrolyte was dropped onto a 19 mm diameter glass fiber membrane. The negative electrode shell, spring contact, negative electrode sheet, glass fiber membrane with added electrolyte, positive electrode sheet, and positive electrode shell were then placed in the following order from top to bottom. The battery was then encapsulated using a coin cell encapsulation machine to obtain the zinc-zinc symmetric battery. Long-term cycle performance testing of the zinc-zinc symmetric battery was conducted at 25°C: the prepared zinc-zinc symmetric battery was placed on a Land CT2001A testing system for cyclic constant current charge-discharge testing (current density set to 0.5 mA·cm⁻¹ during testing). -2 The single constant current charge-discharge process is as follows: first, constant current charging for 1 hour, then constant current discharging for 1 hour. The voltages (including charging and discharging voltages) during the cyclic constant current charge-discharge test are collected, and the results are as follows: Figure 17 The long-term cycle performance curves shown have the vertical axis representing the voltage of the zinc-zinc symmetrical cell and the horizontal axis representing the cycle time. Figure 17 As can be seen, during the 800-hour long-term cycling process, the voltage of the zinc-zinc symmetric battery remained stable throughout, without significant voltage fluctuations, sudden increases, or sudden decreases, demonstrating excellent cycle stability at least for 800 hours. In the initial stage of cycling (within 80 hours), the battery polarization voltage (the difference between charging and discharging voltage) was low, approximately 12 mV, and did not show a significant increasing trend throughout the entire 800-hour cycle. This indicates that the wide-voltage-window electrolyte for aqueous zinc-based batteries in Example 1 formed a stable interface film with the zinc electrodes (positive and negative electrodes), effectively suppressing the redox side reactions of the zinc electrodes. Furthermore, no sudden voltage drop was observed in the long-term cycling performance curves, indicating that the wide-voltage-window electrolyte for aqueous zinc-based batteries in Example 1 can effectively regulate the deposition / dissolution process of zinc ions, suppress the generation and growth of zinc dendrites, and ensure the safety and stability of the battery during long-term cycling. This further verifies the reliability of the wide-voltage-window electrolyte for aqueous zinc-based batteries prepared in Example 1 in long-term cycling applications.

[0112] The morphology of the negative electrode sheets before and after the long-term cycling performance test (800 h of cycling) was characterized, and the results were obtained respectively. Figure 18 a and Figure 18 The SEM shown in b. From Figure 18 As can be clearly seen in Figure b, the surface of the negative electrode sheet after long-term cycle performance testing maintains an intact and flat morphology, and the structure remains undamaged. This phenomenon is consistent with... Figure 8The cycling performance diagrams corroborate each other, indicating that the wide-voltage-window electrolyte prepared in Example 1 for aqueous zinc-based batteries can effectively regulate the zinc ion electrodeposition process and prevent damage to the electrode surface by inhibiting the nucleation and growth of zinc dendrites. This further demonstrates that the wide-voltage-window electrolyte prepared in Example 1 for aqueous zinc-based batteries has a good protective effect on the zinc electrode.

[0113] Table 1

[0114]

[0115] Table 2

[0116]

[0117] Table 3

[0118]

[0119] Table 4

[0120]

[0121] Comparative Example 1 replaced oxonium with propionitrile, resulting in a decrease in both the ionic conductivity and voltage window of the wide-voltage-window electrolyte prepared in Comparative Example 1 for aqueous zinc-based batteries compared to Example 1. The cycle performance of the zinc-iodine battery prepared using the wide-voltage-window electrolyte of Comparative Example 1 was also lower than that of the zinc-iodine battery prepared using the wide-voltage-window electrolyte of Example 1 for aqueous zinc-based batteries. Comparative Example 2, using butadiene-nitrile, also failed to achieve the same technical effect as Example 1, indicating that even though propionitrile and butadiene-nitrile have similar properties to oxonium, they cannot achieve the same effect and cannot synergize well with the first and second functional additives.

[0122] Comparative Example 3 did not include the first functional additive, resulting in the performance of the wide-voltage-window electrolyte for aqueous zinc-based batteries prepared in Comparative Example 3 being inferior to that of Example 3. Furthermore, the cycle performance of the zinc-iodine battery prepared from the wide-voltage-window electrolyte for aqueous zinc-based batteries in Comparative Example 3 was also inferior to that of the zinc-iodine battery prepared from the wide-voltage-window electrolyte for aqueous zinc-based batteries in Example 3. Similarly, Comparative Example 4 did not include the second functional additive, resulting in the performance of the wide-voltage-window electrolyte for aqueous zinc-based batteries prepared in Comparative Example 4 being inferior to that of Example 3. Furthermore, the cycle performance of the zinc-iodine battery prepared from the wide-voltage-window electrolyte for aqueous zinc-based batteries in Comparative Example 4 was also inferior to that of the zinc-iodine battery prepared from the wide-voltage-window electrolyte for aqueous zinc-based batteries in Example 3. This demonstrates that the first and second functional additives play indispensable roles in the present invention.

[0123] Oxynitrile molecules can adsorb onto the negative electrode surface to form a stable interfacial film, inhibiting electrolyte decomposition. Introducing oxynitrile into aqueous electrolytes is expected to significantly broaden the voltage window and improve the energy density of aqueous zinc-based batteries while maintaining electrolyte ionic conductivity.

[0124] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A wide voltage window electrolyte for aqueous zinc-based batteries, characterized in that, include: The mixture comprises a solute, a solvent, a first functional additive, and a second functional additive, wherein the solute is at least one of zinc sulfate, zinc acetate, zinc trifluoromethanesulfonate, and zinc bis(trifluoromethanesulfonyl)imide; the solvent is a mixture of water and oxonium; the first functional additive is at least one of potassium acetate and ammonium acetate; and the second functional additive is fluoroethylene carbonate. The ratio of the molar amount of the solute to the volume amount of the solvent is (0.5~5):1, the unit of molar amount is mol, and the unit of volume amount is L. The ratio of the solute, the first functional additive, and the second functional additive, by molar amount, is (0.5~5):(0.1~0.8):(0.01~0.1).

2. The wide voltage window electrolyte for aqueous zinc-based batteries according to claim 1, characterized in that, The wide voltage window electrolyte for aqueous zinc-based batteries has an ionic conductivity >5.0 mS / cm at 25°C and a voltage window of 0.1~3.1V.

3. The wide voltage window electrolyte for aqueous zinc-based batteries according to claim 1, characterized in that, The volume fraction of ethylene nitrile in the solvent is 10-40%.

4. A method for preparing a wide voltage window electrolyte for aqueous zinc-based batteries, characterized in that, Includes the following steps: Step 1: Mix the solute and solvent until homogeneous to obtain a first mixed solution, wherein the solute is at least one of zinc sulfate, zinc acetate, zinc trifluoromethanesulfonate and zinc bis(trifluoromethanesulfonyl)imide, the solvent is a mixture of water and oxonium, and the ratio of the molar fraction of the solute to the volume fraction of the solvent is (0.5~5):1, the unit of molar fraction is mol, and the unit of volume fraction is L; Step 2: Mix the first functional additive and the first mixed solution until homogeneous to obtain a second mixed solution, wherein the pH value of the second mixed solution is 5.0~7.0, and the first functional additive is at least one of potassium acetate and ammonium acetate; Step 3: Mix the second functional additive and the second mixed solution until homogeneous to obtain a wide voltage window electrolyte for aqueous zinc-based batteries, wherein the second functional additive is fluoroethylene carbonate; Based on the molar amounts, the ratio of solute, first functional additive, and second functional additive in the first mixed solution is (0.5~5):(0.1~0.8):(0.01~0.1).

5. The preparation method according to claim 4, characterized in that, In step 1, the method for obtaining the solvent includes: mixing water and ethylene nitrile at 23~27°C and stirring until homogeneous to obtain a transparent solvent.

6. The preparation method according to claim 4, characterized in that, In step 1, the solute and solvent are mixed and stirred at 23~27℃ until homogeneous to obtain the first mixed solution.

7. The preparation method according to claim 4, characterized in that, In step 2, the first functional additive and the first mixed solution are mixed and stirred at 23~27℃ until homogeneous to obtain the second mixed solution.

8. The preparation method according to claim 4, characterized in that, In step 3, the second functional additive and the second mixed solution are mixed and stirred at 23~27°C until homogeneous to obtain a wide voltage window electrolyte for aqueous zinc-based batteries.

9. The application of the wide voltage window electrolyte for aqueous zinc-based batteries as described in claim 1 in zinc-iodine batteries.

10. The application of the wide voltage window electrolyte for aqueous zinc-based batteries as described in claim 1 as an electrolyte solution.

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