Electrolyte, method for preparing the same, and metal-air battery

Abstract

This invention provides an electrolyte, its preparation method, and a metal-air battery, specifically relating to the field of metal-air battery technology. The electrolyte comprises a hydrophobic ionic liquid solution containing a first metal salt and a hydrophilic ionic liquid solution containing a second metal salt; the volume ratio of the hydrophobic ionic liquid solution containing the first metal salt to the hydrophilic ionic liquid solution containing the second metal salt is 1:(1-5). This electrolyte effectively regulates the solubility and stability of the metal salt, ensuring the conduction of metal ions during the electrochemical reaction. During the electrochemical reaction, the electrolyte facilitates gas diffusion and redox reactions at the positive electrode, ensuring electrode wettability and catalyst stability; simultaneously, it promotes metal deposition and dissolution, reducing uneven metal ion deposition and dendrite growth, improving battery cycle stability, suppressing side reactions, reducing metal electrode corrosion and oxidation, and extending battery life.

Description

Technical Field

[0001] This invention relates to the field of metal-air battery technology, and in particular to an electrolyte, its preparation method, and a metal-air battery. Background Technology

[0002] Metal-air batteries consist of an air electrode, a metal electrode, an electrolyte, and a separator, offering advantages such as high energy density and environmental friendliness. However, in practical applications, several challenges exist regarding the positive electrode, negative electrode, and electrolyte of metal-air batteries.

[0003] Regarding electrolytes, traditional aqueous electrolytes are prone to evaporation and drying out, alkaline environments accelerate electrode corrosion, and carbon dioxide in the air reacts with the electrolyte to form carbonates, clogging the electrodes and requiring frequent maintenance. Ionic liquids, especially room-temperature ionic liquids, offer multiple advantages for metal-air batteries. Addressing the issues of volatility and drying out of traditional aqueous electrolytes, ionic liquids exhibit low volatility and high thermal stability, ensuring long-term electrolyte stability and low maintenance requirements, significantly improving battery durability and operating temperature range.

[0004] The above technologies mainly utilize the low saturated vapor pressure of ionic liquids and apply them to metal-air batteries, solving the problem of easy evaporation and drying of aqueous electrolytes in semi-open systems, which leads to ion transport failure and battery failure. Another existing technology uses an ionic liquid mixed with a metal salt or aqueous solution as the electrolyte for metal-air batteries; however, this method cannot simultaneously improve the problems existing in both the metal negative electrode and the air positive electrode.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One of the objectives of this invention is to provide an electrolyte that addresses at least one of the aforementioned technical problems in the prior art.

[0007] The second objective of this invention is to provide a method for preparing an electrolyte.

[0008] The third objective of this invention is to provide a metal-air battery.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0010] A first aspect of the present invention provides an electrolyte comprising a hydrophobic ionic liquid solution containing a first metal salt and a hydrophilic ionic liquid solution containing a second metal salt, wherein the volume ratio is 1:(1-5).

[0011] The hydrophobic ionic liquid solution containing the first metal salt is formed by dissolving the first metal salt in the hydrophobic ionic liquid.

[0012] The hydrophilic ionic liquid solution containing the second metal salt is formed by dissolving the second metal salt in a hydrophilic ionic liquid.

[0013] The first metal salt and the second metal salt contain the same metal cation.

[0014] Furthermore, in the hydrophobic ionic liquid solution containing the first metal salt, the concentration of the first metal salt is not less than 0.01 mol / L.

[0015] Preferably, in the hydrophobic ionic liquid solution containing the second metal salt, the concentration of the second metal salt is not less than 0.01 mol / L.

[0016] Furthermore, the hydrophobic ionic liquid is composed of a first anion and a first cation.

[0017] The first metal salt is composed of a metal cation and the first anion.

[0018] The first anion is a fluorine-containing anion.

[0019] The fluorinated anion includes at least one of bis(trifluoromethanesulfonyl)imide, di(fluorosulfonyl)imide, di(trifluoroethylsulfonyl)imide, hexafluorophosphate, tetrafluoroborate, and bis(trifluoroacetate).

[0020] Furthermore, the hydrophilic ionic liquid is composed of a second anion and a second cation.

[0021] The second metal salt is composed of the metal cation and the second anion.

[0022] The second anion includes at least one of dicyandiamide, thiocyanate, and methanesulfonate.

[0023] Furthermore, the first cation and the second cation each independently include at least one of imidazole cations, pyridine cations, pyrrole cations, piperidine cations, morpholine cations, quaternary ammonium cations, and quaternary phosphorus cations.

[0024] Furthermore, the metal cation includes zinc ions, aluminum ions, magnesium ions, or lithium ions.

[0025] Furthermore, the electrolyte also includes additives.

[0026] Preferably, the additive includes at least one of DMSO, NMP and DMF.

[0027] Preferably, the additive accounts for 1% to 10% of the volume of the electrolyte.

[0028] The second aspect of the present invention provides a method for preparing the electrolyte, wherein the hydrophobic ionic liquid solution containing a first metal salt, the hydrophilic ionic liquid solution containing a second metal salt, and optional additives are mixed evenly to obtain the electrolyte.

[0029] A third aspect of the present invention provides a metal-air battery, comprising a metal negative electrode, an air positive electrode, a separator, and the electrolyte described in the first aspect.

[0030] Furthermore, the metal anode includes zinc, aluminum, magnesium, or lithium.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects:

[0032] The electrolyte provided by this invention combines hydrophobic and hydrophilic ionic liquids, offering a unique electrolyte system that effectively regulates the solubility and stability of metal salts, ensuring the transport of metal ions during electrochemical reactions. In the electrochemical reaction at the positive electrode, this electrolyte system facilitates gas diffusion and redox reactions, ensuring electrode wettability and catalyst stability, and can alter the reaction pathway through pH adjustment. In the electrochemical reaction at the negative electrode, this electrolyte system optimizes ion migration, promotes metal deposition and dissolution, reduces uneven metal ion deposition and dendrite growth, improves battery cycle stability, suppresses side reactions such as hydrogen evolution, reduces metal electrode corrosion, and extends battery life.

[0033] The electrolyte preparation method provided by this invention completes the preparation through a simple mixing process, without the need for complex synthesis steps, which helps to reduce production costs and improve production efficiency.

[0034] The metal-air battery provided by this invention, in view of the advantages brought by the above-mentioned electrolyte, enables the metal-air battery using this electrolyte to have better positive and negative electrode performance, optimizes the overall performance of the metal-air battery, and achieves higher energy density and longer service life. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 SEM image of the negative electrode surface of the battery assembled with the electrolyte provided in Comparative Example 3 after cycling.

[0037] Figure 2 SEM image of the negative electrode surface of the battery assembled with the electrolyte provided in Comparative Example 2 after cycling. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0039] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.

[0040] A first aspect of the present invention provides an electrolyte comprising a hydrophobic ionic liquid solution containing a first metal salt and a hydrophilic ionic liquid solution containing a second metal salt, wherein the volume ratio is 1:(1-5).

[0041] The hydrophobic ionic liquid solution containing the first metal salt is formed by dissolving the first metal salt in the hydrophobic ionic liquid.

[0042] The hydrophilic ionic liquid solution containing the second metal salt is formed by dissolving the second metal salt in a hydrophilic ionic liquid.

[0043] The first metal salt and the second metal salt contain the same metal cation.

[0044] The electrolyte provided by this invention combines hydrophobic and hydrophilic ionic liquids, offering a unique electrolyte system that effectively regulates the solubility and stability of metal salts, ensuring the transport of metal ions during electrochemical reactions. In the electrochemical reaction at the positive electrode, this electrolyte system facilitates gas diffusion and redox reactions, ensuring electrode wettability and catalyst stability, and can alter the reaction pathway through pH adjustment. In the electrochemical reaction at the negative electrode, this electrolyte system optimizes ion migration, promotes metal deposition and dissolution, reduces uneven metal ion deposition and dendrite growth, improves battery cycle stability, suppresses side reactions such as hydrogen evolution, reduces metal electrode corrosion, and extends battery life.

[0045] The specific analysis of the performance improvement of the electrolyte system provided by this invention on metal-air batteries is as follows:

[0046] 1. Effects on the positive electrode (air electrode):

[0047] Oxygen diffusion and reduction reaction: On an air electrode, oxygen needs to diffuse effectively to the electrode surface and undergo a reduction reaction. Hydrophilic ionic liquids may help create an environment more favorable for oxygen dissolution and transport, optimizing reaction pathways and thus promoting the oxygen reductive reaction (ORR).

[0048] Electrolyte stability: In a semi-open structure, hydrophilic ionic liquids can maintain a more stable trace water content and maintain higher ionic conductivity, which is beneficial for ion transport; hydrophobic ionic liquids may help to ensure a higher electrochemical window and reduce the possibility of electrolyte decomposition.

[0049] 2. Influence of the negative electrode (metal electrode):

[0050] Metal deposition and dissolution: The deposition and dissolution processes of metals are crucial at the negative electrode of a metal-air battery. Hydrophilic ionic liquids may provide better ion transport channels, promoting the migration of metal ions.

[0051] Electrode protection: Hydrophobic ionic liquids may help reduce the water content on the electrode surface, reduce the side reaction of hydrogen evolution corrosion of metal electrodes, and extend battery life. Furthermore, fluorine-containing anions may form a more stable SEI layer at the interface, promoting uniform deposition of metal ions.

[0052] Interaction between electrolyte and metal: Hydrophobic ionic liquids may form a stable interfacial electric double layer with metal electrodes, which can create a more uniform interfacial electric field, suppress the tip effect, reduce the uneven deposition of metal ions and dendrite growth, and improve the cycle stability of the battery.

[0053] Suppression of side reactions: Hydrophobic ionic liquids may help suppress water-induced side reactions, such as hydrolysis and hydrogen production, which can consume metal electrodes and reduce battery efficiency.

[0054] In summary, hydrophilic and hydrophobic ionic liquids play different roles in the positive and negative electrodes of metal-air batteries, affecting the electrode reaction kinetics, stability, and efficiency. By rationally designing the hydrophilicity and hydrophobicity of the electrolyte in this invention, and simultaneously introducing metal salts, the overall performance of the battery is optimized, achieving higher energy density and longer lifespan.

[0055] Typical, but not limiting, volume ratios of hydrophobic ionic liquid solutions containing a first metal salt and hydrophilic ionic liquid solutions containing a second metal salt can be, for example, 1:1, 1:2, 1:3, 1:4, or 1:5, or any value within the range of 1:(1 to 5).

[0056] If the volume ratio of the hydrophobic ionic liquid solution containing the first metal salt to the hydrophilic ionic liquid solution containing the second metal salt is greater than 1:1, meaning the volume of the hydrophobic ionic liquid solution containing the first metal salt is larger, it will affect the gas reaction on the positive electrode side, change the reaction path, increase the reaction energy barrier, and affect the transport of reaction and product species, leading to battery failure. If the volume ratio of the hydrophobic ionic liquid solution containing the first metal salt to the hydrophilic ionic liquid solution containing the second metal salt is less than 1:5, meaning the volume of the hydrophilic ionic liquid solution containing the first metal salt is more than five times the volume of the hydrophobic ionic liquid solution containing the first metal salt, it will cause an increase in hydrogen evolution and corrosion side reactions on the negative electrode side, leading to more intense dendrite growth, resulting in dead zinc or dendrite short circuits, etc.

[0057] Furthermore, in the hydrophobic ionic liquid solution containing the first metal salt, the concentration of the first metal salt is not less than 0.01 mol / L, and is any value within the solubility range.

[0058] Preferably, in the hydrophobic ionic liquid solution containing the second metal salt, the concentration of the second metal salt is not less than 0.01 mol / L, and is any value within the solubility range.

[0059] It should be noted that the concentration of the first metal salt in the hydrophobic ionic liquid solution can be the same as or different from the concentration of the second metal salt in the hydrophilic ionic liquid solution.

[0060] Furthermore, the hydrophobic ionic liquid is composed of a first anion and a first cation.

[0061] The first metal salt is composed of a metal cation and the first anion.

[0062] The first anion is a fluorine-containing anion.

[0063] The fluorinated anion includes at least one of bis(trifluoromethanesulfonyl)imide, di(fluorosulfonyl)imide, di(trifluoroethylsulfonyl)imide, hexafluorophosphate, tetrafluoroborate, and bis(trifluoroacetate).

[0064] Furthermore, the hydrophilic ionic liquid is composed of a second anion and a second cation.

[0065] The second metal salt is composed of the metal cation and the second anion.

[0066] The second anion includes at least one of dicyandiamide, thiocyanate, and methanesulfonate.

[0067] Furthermore, the first cation and the second cation each independently include at least one of imidazole cations, pyridine cations, pyrrole cations, piperidine cations, morpholine cations, quaternary ammonium cations, and quaternary phosphorus cations.

[0068] Furthermore, the metal cation includes zinc ions, aluminum ions, magnesium ions, or lithium ions.

[0069] Typical, but not limiting, hydrophobic ionic liquids may be, for example, 1-ethyl-3-methylimidazolium bis(trifluoromethane)sulfonylimide, 1-butyl-1-methylpyrrole bis(trifluoromethane)sulfonylimide, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium hexafluorophosphate, or 1-butyl-3-methylimidazolium tetrafluoroborate.

[0070] Typical, but not limiting, first metal salts may be, for example, zinc bis(trifluoromethanesulfonyl)imide, aluminum bis(trifluoromethanesulfonyl)imide, magnesium bis(trifluoromethanesulfonyl)imide, or lithium bis(trifluoromethanesulfonyl)imide.

[0071] Typical, but not limiting, hydrophilic ionic liquids may include, for example, 1-ethyl-3-methylimidazolium dicyandiamide, N-butyl-N-methylpyrrole dicyandiamide, or 1-butyl-1-methylpyrrole dicyandiamide.

[0072] Typical, but not limiting, second metal salts may be, for example, zinc dicyandiamide, aluminum dicyandiamide, magnesium dicyandiamide, or lithium dicyandiamide.

[0073] Furthermore, the electrolyte also includes additives.

[0074] Preferably, the additive includes at least one of DMSO, NMP and DMF.

[0075] Preferably, the additive accounts for 1% to 10% of the volume of the electrolyte.

[0076] Additives can improve the ionic conductivity of the electrolyte and promote synergistic effects with other substances in the electrolyte, thereby enhancing battery performance.

[0077] Typically, but not limitingly, the volume percentage of the additive in the electrolyte can be, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, or any value within the range of 1% to 10%.

[0078] The second aspect of the present invention provides a method for preparing the electrolyte, wherein the hydrophobic ionic liquid solution containing a first metal salt, the hydrophilic ionic liquid solution containing a second metal salt, and optional additives are mixed evenly to obtain the electrolyte.

[0079] The electrolyte preparation method provided by this invention completes the preparation through a simple mixing process, without the need for complex synthesis steps, which helps to reduce production costs and improve production efficiency.

[0080] A third aspect of the present invention provides a metal-air battery, comprising a metal negative electrode, an air positive electrode, a separator, and the electrolyte described in the first aspect.

[0081] The metal-air battery provided by this invention, in view of the advantages brought by the above-mentioned electrolyte, enables the metal-air battery using this electrolyte to have better positive and negative electrode performance, optimizes the overall performance of the metal-air battery, and achieves higher energy density and longer service life.

[0082] Furthermore, the metal anode includes zinc, aluminum, magnesium, or lithium.

[0083] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0084] Example 1

[0085] This embodiment provides an electrolyte, the preparation method of which is as follows:

[0086] 1. Synthesis of Zn(DCA)2: 2.00 g of NaDCA (sodium dicyandiamide) was added to a 250 mL borosilicate glass bottle, followed by 50 mL of water and stirring to dissolve. 13.39 g of Zn(NO)3 was added to a 15 mL sample vial and shaken until completely dissolved to obtain a Zn(NO)3 solution. The Zn(NO)3 solution was slowly added to the NaDCA solution using a dropper, resulting in a white precipitate. After stirring for 6 h, the solution was washed three times by centrifugation with ultrapure water and dried under vacuum at 40 °C for 72 h to obtain Zn(DCA)2 (zinc dicyandiamide).

[0087] 2. Take 3 mL of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIMTFSI) ionic liquid, add 0.0192 g of Zn(TFSI)2 (zinc bis(trifluoromethanesulfonyl)imide), and sonicate for 2 h until completely dissolved to obtain a hydrophobic ionic liquid solution of Zn(TFSI)2.

[0088] 3. Take 3 mL of 1-ethyl-3-methylimidazolium dicyandiamide (EMIMDCA) ionic liquid, add 0.0060 g of Zn(DCA)2, and sonicate for 10 min until completely dissolved to obtain a hydrophilic ionic liquid solution of Zn(DCA)2.

[0089] 4. Take 80 μL of hydrophobic ionic liquid solution of Zn(TFSI)2 and 400 μL of hydrophilic ionic liquid solution of Zn(DCA)2, add 20 μL of N,N-dimethylformamide (DMF) and mix. Mix well with a vortex mixer to obtain the electrolyte.

[0090] Example 2

[0091] This embodiment provides an electrolyte. Unlike embodiment 1, the amount of DMF added in step 4 is 4.8 μL. The other raw materials and methods are the same as in embodiment 1, and will not be repeated here.

[0092] Example 3

[0093] This embodiment provides an electrolyte. The difference from Embodiment 1 is that the amount of DMF added in step 4 is 53 μL. The other raw materials and methods are the same as in Embodiment 1, and will not be repeated here.

[0094] Example 4

[0095] This embodiment provides an electrolyte. Unlike embodiment 1, the amount of DMF added in step 4 is 80 μL. The other raw materials and methods are the same as in embodiment 1, and will not be repeated here.

[0096] Example 5

[0097] This embodiment provides an electrolyte. Unlike Example 1, 240 μL of each of the two ionic liquids are used. The other raw materials and methods are the same as in Example 1, and will not be repeated here.

[0098] Example 6

[0099] This embodiment provides an electrolyte. Unlike Example 1, 800 μL of the hydrophilic ionic liquid solution of Zn(DCA)2 is used. The other raw materials and methods are the same as in Example 1, and will not be repeated here.

[0100] Comparative Example 1

[0101] This comparative example provides an electrolyte, prepared by the following method:

[0102] Weigh 33.67g KOH and 4.39g Zn(Ac)2·2H2O, stir to dissolve and cool, then dilute to volume with a 100mL volumetric flask to obtain the electrolyte.

[0103] Comparative Example 2

[0104] This comparative example provides an electrolyte solution. 240 μL of the hydrophobic ionic liquid solution of Zn(TFSI)2 from Example 1 was taken and 10 μL of N,N-dimethylformamide (DMF) was added and mixed. The mixture was then vortexed to obtain the electrolyte solution.

[0105] Comparative Example 3

[0106] This comparative example provides an electrolyte solution. 240 μL of the hydrophilic ionic liquid solution of Zn(DCA)2 from Example 1 was taken and 10 μL of N,N-dimethylformamide (DMF) was added and mixed. The mixture was then vortexed to obtain the electrolyte solution.

[0107] Test Example 1

[0108] The electrolytes from Comparative Examples 2 and 3 were assembled into zinc symmetric cells. The electrochemical performance of the zinc symmetric cells was tested, and their morphology was characterized.

[0109] The positive and negative electrode shells, gaskets, and springs are immersed in ethanol and sonicated for 1 hour, then dried by blowing air and stored in the battery box.

[0110] Whatman GF-A diaphragm: 19mm in diameter.

[0111] Zinc sheet processing: Cut into 11mm pieces using a punching machine, place in centrifuge tubes, soak in 1mol / L HCl for 10s before installing the battery, then wash in the order of pure water-ethanol-pure water, and finally wipe dry with non-woven cloth.

[0112] The assembly sequence of a zinc symmetric battery is as follows: positive electrode shell - gasket - zinc sheet - separator - add 100μL electrolyte - zinc sheet - gasket - spring sheet - negative electrode shell.

[0113] Constant current test: after standing for 0.5 hours, 0.1 mA / cm 2 Discharge for 2 hours, charge for 2 hours. The data obtained are shown in Table 1 below.

[0114] Table 1

[0115] Test Example 1 Number of cycles Comparative Example 2 98 Comparative Example 3 24

[0116] As can be seen from Table 1, the hydrophobic ionic liquid in Comparative Example 2 and the hydrophilic ionic liquid in Comparative Example 3 are more conducive to the dissolution and deposition process of zinc. After assembling zinc symmetric batteries, charge-discharge cycle tests were conducted. The cycle life of the battery assembled with the hydrophobic ionic liquid electrolyte is about 5 times that of the hydrophilic ionic liquid electrolyte.

[0117] Depend on Figure 1 and Figure 2 The comparison shows that the deposition morphology obtained by using a hydrophobic ionic liquid electrolyte is more uniform and the zinc core is smaller.

[0118] Test Example 2

[0119] The electrolytes obtained from the examples and comparative examples were assembled into zinc-air batteries, and the electrochemical performance of the zinc-air batteries was tested.

[0120] The positive and negative electrode shells and gaskets were immersed in ethanol and sonicated for 1 hour, then dried by blowing air and stored in the battery box.

[0121] Whatman GF-D diaphragm: 19mm in diameter.

[0122] Zinc sheet processing: Cut into 11mm pieces using a punching machine, place in centrifuge tubes, soak in 1mol / L HCl for 10s before installing the battery, then wash in the order of pure water-ethanol-pure water, and finally wipe dry with non-woven cloth.

[0123] Ink preparation: Weigh 0.0270g RuO2 and 0.0135g 40wt% Pt / C, add 5mL anhydrous ethanol, vortex mix, then add 200μL 10wt% Nafion solution, sonicate for 10min, spray onto 5cm×6cm carbon paper, infrared dry, and then vacuum dry for 12h.

[0124] The assembly sequence of a zinc-air battery is as follows: positive electrode shell - nickel foam - positive electrode sheet - separator - add 250μL electrolyte - zinc sheet - gasket - negative electrode shell.

[0125] Constant current test: after standing for 0.5 hours, 0.1 mA / cm 2 Discharge for 15 minutes, then charge for 15 minutes. The data obtained are shown in Table 2 below.

[0126] Table 2

[0127] Test Example 2 Number of cycles Example 1 96 Example 2 95 Example 3 88 Example 4 63 Example 5 95 Example 6 41 Comparative Example 1 30 Comparative Example 2 0 Comparative Example 3 34

[0128] Table 2 shows that, compared to Comparative Example 1, the zinc-air coin cell using an ionic liquid electrolyte generally has a longer cycle life. This indicates that in the coin cell system, battery failure problems caused by the evaporation and drying of traditional aqueous electrolytes, the easy carbonation of strongly alkaline solutions, and severe hydrogen evolution and dendrite formation can be avoided with ionic liquids. Comparative Example 2 shows that a purely hydrophobic ionic liquid does not support the charging and discharging of zinc-air batteries; however, Examples 1 and 5 show that within a hydrophobic:hydrophilic ionic liquid volume ratio of 1:5, the cycle life is longer than that of a single ionic liquid; Example 6 shows that when the volume ratio of hydrophobic to hydrophilic ionic liquid is 1:10, the battery cycle life becomes shorter; Examples 1, 2, and 3 show that when the additive volume fraction is between 1% and 10%, the cycle life of the zinc-air battery is about three times that of Comparative Example 3; Example 4 shows that when the additive volume fraction is greater than 10%, the battery cycle life becomes shorter.

[0129] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An electrolyte, characterized in that, This includes hydrophobic ionic liquid solutions containing a first metal salt and hydrophilic ionic liquid solutions containing a second metal salt, with a volume ratio of 1:(1~5). The hydrophobic ionic liquid solution containing the first metal salt is formed by dissolving the first metal salt in a hydrophobic ionic liquid. The hydrophilic ionic liquid solution containing the second metal salt is formed by dissolving the second metal salt in a hydrophilic ionic liquid; The first metal salt and the second metal salt contain the same metal cation; The hydrophobic ionic liquid is composed of a first anion and a first cation; The first metal salt is composed of a metal cation and the first anion; The first anion is a fluoride-containing anion; The fluorinated anion includes at least one of bis(trifluoromethanesulfonyl)imide, di(fluorosulfonyl)imide, di(trifluoroethylsulfonyl)imide, hexafluorophosphate, tetrafluoroborate and bis(trifluoroacetate); The hydrophilic ionic liquid is composed of a second anion and a second cation; The second metal salt is composed of the metal cation and the second anion; The second anion includes at least one of dicyandiamide, thiocyanate, and methanesulfonate. The first cation and the second cation each independently include at least one of imidazole cations, pyridine cations, pyrrole cations, piperidine cations, morpholine cations, quaternary ammonium cations, and quaternary phosphorus cations.

2. The electrolyte according to claim 1, characterized in that, In the hydrophobic ionic liquid solution containing the first metal salt, the concentration of the first metal salt is not less than 0.01 mol / L.

3. The electrolyte according to claim 1, characterized in that, In the hydrophilic ionic liquid solution containing the second metal salt, the concentration of the second metal salt is not less than 0.01 mol / L.

4. The electrolyte according to any one of claims 1 to 3, characterized in that, The metal cations include zinc ions, aluminum ions, magnesium ions, or lithium ions.

5. The electrolyte according to any one of claims 1 to 3, characterized in that, It also includes additives.

6. The electrolyte according to claim 5, characterized in that, The additives include at least one of DMSO, NMP and DMF.

7. The electrolyte according to claim 5, characterized in that, The additive accounts for 1% to 10% of the volume of the electrolyte.

8. A method for preparing the electrolyte according to any one of claims 1 to 7, characterized in that, The electrolyte is obtained by uniformly mixing the hydrophobic ionic liquid solution containing the first metal salt, the hydrophilic ionic liquid solution containing the second metal salt, and optional additives.

9. A metal-air battery, characterized in that, It includes a metal negative electrode, an air positive electrode, a diaphragm, and the electrolyte as described in any one of claims 1 to 7.

10. The metal-air battery according to claim 9, characterized in that, The metal anode includes zinc, aluminum, magnesium, or lithium.

Images