Aqueous electrolyte and energy storage device

Abstract

The present invention proposes an aqueous electrolyte and an energy storage device, which relates to the technical field of basic electrical components. The aqueous electrolyte includes water, a hydrogen bond donor and a hydrogen bond acceptor, and an electrolyte salt; the hydrogen bond donor and the hydrogen bond acceptor form a eutectic, and the eutectic is used to lock water. In the technical solution of the present invention, by using the hydrogen bond donor and the hydrogen bond acceptor to form a eutectic, water, the hydrogen bond donor and the hydrogen bond can be combined through the action of hydrogen bonds to form a hydrogen bond network, and water molecules can be fixed in the hydrogen bond network, thereby locking water, reducing the evaporation of water in the aqueous electrolyte, and realizing that the aqueous electrolyte can still work normally in the case of very little water; and in the case of low water content, the occurrence of hydrogen evolution can be reduced, thereby increasing the working voltage window of the electrolyte.

Description

Technical Field

[0001] The invention relates to the technical field of basic electrical components, and in particular to an aqueous electrolyte and an energy storage device. Background Art

[0002] Zinc ion energy storage devices are safe, economical and environmentally friendly energy storage devices. Since the electrolyte used is an aqueous electrolyte, it can be mass-produced under normal conditions without the need for oxygen-free, dry assembly lines, which greatly reduces the manufacturing costs of manufacturers.

[0003] However, the thermodynamic instability of zinc metal in aqueous electrolytes remains the main bottleneck for its commercialization, because water is used as the main carrier of the electrolyte, which will cause hydrogen to be continuously generated during the charging and discharging process, leading to failure of the energy storage device; and most of the current zinc ion energy storage devices use low-concentration metal salts added to water as the electrolyte, which will lead to failure of the energy storage device due to water loss after long-term storage. Summary of the invention

[0004] The main purpose of the present invention is to provide an aqueous electrolyte and an energy storage device, aiming to improve the water absorption of the electrolyte and reduce the hydrogen evolution effect of the energy storage device.

[0005] To achieve the above object, the present invention provides an aqueous electrolyte, which includes water, a hydrogen bond donor and a hydrogen bond acceptor, and an electrolyte salt;

[0006] The hydrogen bond donor and the hydrogen bond acceptor form a eutectic agent, and the eutectic agent is used for locking water.

[0007] In one embodiment, the water-locking function of the eutectic agent is:

[0008] When the humidity is lower than 10%, the water in the aqueous electrolyte exists in the form of hydrated ions;

[0009] When the humidity is not less than 10%, the aqueous electrolyte absorbs moisture in the air.

[0010] In one embodiment, the functional group of the hydrogen bond donor includes: an amino group, a carbonyl group or a carboxyl group. Preferably, the hydrogen bond donor includes at least one of urea, thiourea, amides, polyols, sugars and carboxylic acids.

[0011] The hydrogen bond acceptor comprises at least one of a quaternary ammonium salt, a zwitterion and a metal salt;

[0012] The eutectic agent is liquid at 30°C.

[0013] In one embodiment, the electrolyte salt includes at least one of a halogen zinc salt, a halogen lithium salt, a halogen calcium salt, a potassium carboxylate, and an ammonium carboxylate;

[0014] The electrolyte salt is dissolved in the eutectic agent.

[0015] In one embodiment, the electrolyte salt and the eutectic agent have opposite acidity and alkalinity, and the pH value of the aqueous electrolyte is 6-8.

[0016] The present invention further provides an energy storage device, comprising the aqueous electrolyte as described above, wherein the energy storage device stores energy in a capacitor and / or a battery;

[0017] The chargeable voltage of the energy storage device is not less than 1.23V.

[0018] In one embodiment, the energy storage device comprises a battery, and the positive electrode of the battery comprises a redox material.

[0019] In one embodiment, the energy storage device comprises a battery, the positive electrode of the battery comprises an ion intercalation material, and the intercalation ions of the ion intercalation material comprise hydrogen ions.

[0020] In one embodiment, the energy storage device is provided with an opening, and the opening is used for exchanging moisture with the air.

[0021] In one embodiment, the opening is covered with a hydrophobic layer and / or a semi-permeable membrane layer.

[0022] In the technical solution of the present invention, by adopting the hydrogen bond donor and the hydrogen bond acceptor to form a eutectic, water, the hydrogen bond donor and the hydrogen bonds can be combined through the action of hydrogen bonds to form a hydrogen bond network, and water molecules can be fixed in the hydrogen bond network, thereby locking the moisture and reducing the evaporation of water in the aqueous electrolyte, so that the aqueous electrolyte can still work normally in the case of very little water; and in the case of low water content, the occurrence of hydrogen evolution can be reduced, thereby increasing the working voltage window of the electrolyte.

[0023] In addition, by introducing water-locking salts into the electrolyte salt, the water-locking ability of the electrolyte is further improved, and the pH of the electrolyte is made neutral by acid-base preparation of the electrolyte salt, thereby improving the shelf life of the electrochemical device. This electrolyte can not only match supercapacitors, but also can be used in batteries containing ion intercalation cathode materials, and because of its high salt concentration characteristics, it reduces the dissolution of cathode materials, especially redox conversion cathode materials, further improving the battery's cycle performance and shelf life. Its water-locking design can effectively avoid the risk of battery expansion caused by hydrogen evolution, and its ability to dynamically exchange water molecules with air shows excellent scalability for large-scale energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a graph showing the experimental results of the weight change of the electrolyte provided in Comparative Examples 1 to 5 of the present invention;

[0026] Figure 2 The graph is a result of the experimental analysis of the weight change of the electrolyte provided in Example 1, Example 2 and Comparative Example 6 of the present invention;

[0027] Figure 3 This is a graph showing the pH value test results of the electrolyte provided in Example 1, Example 3 and Comparative Example 5 of the present invention;

[0028] Figure 4 A graph showing the cycle life test results of supercapacitors made of the electrolytes provided in Example 4 and Comparative Example 6 of the present invention;

[0029] Figure 5 A graph showing the voltage detection results of supercapacitors made of the electrolytes provided in Example 4 and Comparative Example 6 of the present invention;

[0030] Figure 6 This is a graph showing the compatibility test results of the electrolyte and the electrode material provided in Comparative Examples 5 and 7 of the present invention;

[0031] Figure 7 This is a graph showing the discharge performance test results of zinc-manganese batteries made with the electrolytes provided in Example 4 and Comparative Example 8 of the present invention.

[0032] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0033] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0034] It should be noted that, in the embodiments, those without specifying specific conditions are carried out according to normal conditions or conditions recommended by the manufacturer. Those without specifying the manufacturer of reagents or instruments used are conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, and "A and / or B" is taken as an example, including schemes A, B, or A and B that meet the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of the technical schemes is contradictory or cannot be achieved, it should be considered that the combination of such technical schemes does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work, all belong to the scope of protection of the present invention.

[0035] Zinc ion energy storage devices are safe, economical and environmentally friendly energy storage devices. Since the electrolyte used is an aqueous electrolyte, it can be mass-produced under normal conditions without the need for oxygen-free, dry assembly lines, which greatly reduces the manufacturing costs of manufacturers.

[0036] However, taking the commonly used zinc battery as an example, the thermodynamic instability of zinc metal in aqueous zinc ion energy storage devices is still the main bottleneck for its commercialization, because water is used as the main carrier of the electrolyte. Since the decomposition potential of water is about 1.23V, and the voltage required for daily use is often higher than this number, the battery charging and discharging process will involve the decomposition of water, the production of hydrogen and the release of electrons. The reaction equation is usually: 2H++2e-→H2. This means that hydrogen will continue to be produced during the charging and discharging process, causing the energy storage device to fail; in addition, the protons of the electrolyte will also react with zinc metal. At present, most of the low-concentration metal salts are added to water as the electrolyte of the zinc ion energy storage device, which will cause the energy storage device to fail due to water loss after long-term storage.

[0037] In view of this, the present invention proposes an aqueous electrolyte, which includes water, a hydrogen bond donor and a hydrogen bond acceptor, and an electrolyte salt; the hydrogen bond donor and the hydrogen bond acceptor form a eutectic, and the eutectic is used to lock water.

[0038] In the technical solution of the present invention, by adopting the hydrogen bond donor and the hydrogen bond acceptor to form a eutectic, water, the hydrogen bond donor and the hydrogen bond can be combined through the action of hydrogen bonds to form a hydrogen bond network, and water molecules are fixed in the hydrogen bond network, thereby locking in moisture and reducing the evaporation of water in the aqueous electrolyte, so that the aqueous electrolyte can still work normally in the presence of very little water; and this solution also effectively reduces the activity of water in the electrolyte, thereby effectively inhibiting the occurrence of hydrogen evolution side reactions, achieving stable circulation of the zinc negative electrode, and thereby improving the working voltage window of the electrolyte.

[0039] See also Figure 1 , Figure 1 The weight change test results of the electrolytes provided in Comparative Examples 1 to 5 of the present invention at room temperature with a humidity of 30%. Figure 1 It can be seen that when there is only a single hydrogen bond donor or hydrogen bond acceptor (saturated solution of urea and saturated solution of choline), the weight of the electrolyte decreases when the air humidity is 30%, indicating that the electrolyte is losing water. When the hydrogen bond donor and the hydrogen bond acceptor are combined to form a eutectic, the original water loss situation turns into water absorption. The water absorption performance of the eutectic (ethylene glycol) that originally slightly absorbs water is further improved after the combination.

[0040] In one embodiment, the water-locking function of the eutectic is: when the humidity is lower than 10%, the water in the aqueous electrolyte exists in the form of hydrated ions; when the humidity is not lower than 10%, the aqueous electrolyte absorbs moisture in the air.

[0041] In the technical solution of the present invention, by utilizing the characteristic of the electrolyte that can lock in moisture at high concentrations, when the relative humidity of the air is 0-10%, the ionic bonds formed by the ionization of the electrolyte salt can fix water to form hydrated ions; when the relative humidity of the air is 10%-100%, the molecular structure of the aqueous electrolyte contains ionic bonds that can interact with water molecules in the air. As the number of water molecules increases, the interaction between the ionic bonds and the water molecules increases, thereby absorbing moisture from the air and achieving the effect of water absorption and moisturizing.

[0042] In one embodiment, the functional group of the hydrogen bond donor includes: amino, carbonyl or carboxyl. Preferably, the hydrogen bond donor includes at least one of urea, thiourea, amides, polyols, sugars and carboxylic acids; the hydrogen bond acceptor includes at least one of quaternary ammonium salts, zwitterions and metal salts; the eutectic agent is liquid at 30°C.

[0043] In the technical solution of the present invention, by adopting the above-mentioned types of hydrogen bond donors and hydrogen bond acceptors, a deep eutectic solvent is formed, which has a higher electrical conductivity than ordinary organic solvents; at the same time, the deep eutectic solvent combines with water molecules to reconstruct the hydrogen bond network in the electrolyte, effectively inhibiting the reactivity of water, locking in moisture when the moisture content is low, further reducing moisture volatilization, and reducing water participation in the electrolysis reaction, thereby reducing the occurrence of hydrogen evolution; by adopting suitable hydrogen bond donors and hydrogen bond acceptors, the eutectic temperature of the co-solvent can be adjusted so that the co-solvent is liquid at 30°C, so as to be applied to electrical energy storage devices.

[0044] Specifically, in some embodiments of the present invention, the molar ratio between the hydrogen bond donor and the hydrogen bond acceptor is (3-10):(1-3), preferably 2:1.

[0045] In one embodiment, the electrolyte salt includes at least one of halogen zinc salt, halogen lithium salt, halogen calcium salt, potassium carboxylate and ammonium carboxylate; and the electrolyte salt is dissolved in the eutectic agent.

[0046] In the technical solution of the present invention, at least one of halogen zinc salt, halogen lithium salt, halogen calcium salt, potassium carboxylate and ammonium carboxylate is used as an electrolyte salt, and the electrolyte salt directly provides the metal ions required for the negative electrode, or acts as a water-locking salt to further improve the water-locking performance of the electrolyte. It is understandable that when the electrolyte salt is a metal salt, the metal salt acts as both an electrolyte salt and a hydrogen bond acceptor, which can further improve the water-locking efficiency and achieve the effect of absorbing water from air with high humidity.

[0047] See also Figure 2 , Figure 2 The weight change experimental results of the electrolyte provided in Example 1, Example 2 and Comparative Example 6 of the present invention at room temperature with a humidity of 65%. Figure 2 It can be seen that the water absorption of the three combinations of single high concentration ZnCl2, deep eutectic solution with a molar ratio of urea to choline of 1:6:3, deep eutectic solution with a molar ratio of urea to choline of 6:3 and ZnCl2 solution at a humidity of 65% shows that the combination of urea plus choline absorbs less water, and the water absorption performance is improved after adding ZnCl2.

[0048] In one embodiment, the electrolyte salt includes at least one of ZnCl2, LiCl, ZnAc2, KAc and NH4Ac; and / or, the electrolyte salt accounts for 6% to 20% by mass in the aqueous electrolyte.

[0049] In the technical solution of the present invention, by using at least one of ZnCl2, LiCl, ZnAc2, KAc and NH4Ac as the electrolyte salt, the above electrolyte salt can be used as a hydrogen bond acceptor to significantly improve the conductivity of the electrolyte. At the same time, the ionic bonds of the electrolyte salt can also combine with water molecules, thereby further improving the water locking efficiency and achieving the effect of absorbing water from the air with higher humidity. Different electrolyte salts have different water absorption concentrations in the air and different effects. Therefore, water-locking salts can be used in combination with other active material electrolytes.

[0050] In one embodiment, the electrolyte salt and the eutectic agent have opposite acidity and alkalinity, and the pH value of the aqueous electrolyte is 6-8.

[0051] In the technical solution of the present invention, the pH value of the aqueous electrolyte can be adjusted by using an electrolyte salt with an opposite acidity and alkalinity to the eutectic agent. For example, when the eutectic agent is acidic, the electrolyte is an alkaline electrolyte, and when the cosolvent is alkaline, the electrolyte is an acidic electrolyte, so that it can be applied in different water-based energy storage systems. Since various water-based energy storage systems have different requirements for the pH value of the electrolyte, the application range of the aqueous electrolyte with adjustable pH is very broad. For example, the aqueous solution of carboxylate is alkaline, zinc metal salt is acidic, and lithium salt is neutral, thereby forming a zinc ion battery that can achieve stable circulation under weak acidic conditions, and a zinc nickel battery with good performance under weak alkaline conditions, etc. The pH of the final aqueous solution is adjusted by the acidity and alkalinity of different salts and cosolvents.

[0052] See also Figure 3 , Figure 3 The pH value test results of the electrolyte provided by Example 1, Example 3 and Comparative Example 5 of the present invention. Figure 3 It can be seen that the pH value of urea + choline itself is 6.6. When KAc is added to the eutectic solution of urea + choline, the pH value can be adjusted to 8. When ZnCl2 is added to the eutectic salt solution of urea + choline, the pH value can be adjusted to 6.

[0053] The present invention also provides an energy storage device, comprising the aqueous electrolyte as described above, wherein the energy storage device stores energy in the form of capacitor energy storage and / or battery energy storage; and the chargeable voltage of the energy storage device is not less than 1.23V.

[0054] In the technical solution of the present invention, by adopting the aqueous electrolyte to prepare the energy storage device, the volatilization of water can be reduced, thereby extending the life of the energy storage device; it can be applied to capacitor energy storage and battery energy storage. The aqueous electrolyte can reduce the hydrogen evolution phenomenon caused by the electrolysis reaction of water and increase their electrochemical window, thereby improving the cycle life and battery performance of capacitor energy storage and battery energy storage.

[0055] See also Figure 4 and Figure 5 , Figure 4 The electrolyte provided in Example 4 and Comparative Example 6 of the present invention is used to prepare a supercapacitor, and the cycle performance test results of the supercapacitor are shown in FIG. 1 , wherein the positive electrode is an activated carbon electrode and the negative electrode is a zinc electrode. Figure 4 It can be seen that the supercapacitor prepared by the electrolyte of Example 5 can still achieve a coulombic efficiency of about 80% after 30 cycles, while the supercapacitor prepared by the electrolyte of Comparative Example 4 has a coulombic efficiency close to 0 after less than 20 cycles, and the supercapacitor fails.

[0056] Figure 5The electrolyte provided in Example 4 and Comparative Example 6 of the present invention is used to make a supercapacitor, and the voltage test results of the supercapacitor during the cycle process are shown in FIG. 1 , wherein the positive electrode is an activated carbon electrode and the negative electrode is a zinc electrode. Figure 5 It can be seen that the peak voltage of the supercapacitor prepared in Example 4 is slightly lower than the peak voltage of the supercapacitor prepared in Comparative Example 6, indicating that the addition of the eutectic agent increases the ion concentration after desolvation compared with the pure metal salt. In addition, since the addition of the eutectic agent increases the electrochemical window, the hydrogen evolution inhibition characteristic changes from linear to nonlinear in the charging curve, thereby inhibiting the hydrogen evolution phenomenon and improving the cycle life of the supercapacitor.

[0057] In one embodiment, the energy storage device includes a battery, and the positive electrode of the battery includes a redox material. In the technical solution of the present invention, by using a redox material as the positive electrode of the battery, the deep eutectic electrolyte composed of a hydrogen bond donor and a hydrogen bond acceptor contains a hydrogen bond donor group, which can inhibit the dissolution of the positive electrode material in the electrolyte and improve the service life of the battery.

[0058] refer to Figure 6 , Figure 6 The results of the electrolyte compatibility test for iodine provided in Comparative Examples 5 and 7 of the present invention, wherein iodine is used as a redox electrode material. Figure 6 It can be seen that when a pure ZnCl2 solution is used, iodine has completely diffused after 24 hours of storage; while in the choline + urea electrolyte, the diffusion of I is well suppressed, indicating that the deep eutectic electrolyte composed of eutectic materials can inhibit the dissolution of redox electrode materials in the electrolyte, thereby inhibiting the shuttling phenomenon.

[0059] In one embodiment, the energy storage device includes a battery, the positive electrode of the battery includes an ion intercalation material, and the intercalation ions of the ion intercalation material include hydrogen ions. In the technical solution of the present invention, by using the hydrogen ion intercalation material as the positive electrode material of the battery, when the water content in the aqueous electrolyte increases, the hydrogen ion content will also increase accordingly, and the hydrogen ions can significantly improve the battery performance by inserting into the positive electrode material of the battery, which shows that when the aqueous electrolyte absorbs water from the air, it has an excellent effect on the battery itself.

[0060] refer to Figure 7 , Figure 7 The electrolyte provided in Example 4 and Comparative Example 8 of the present invention is used to prepare a zinc-manganese battery, and the discharge performance test results of the zinc-manganese battery are tested. The positive electrode of the zinc-manganese battery is a manganese dioxide electrode, and the negative electrode is a zinc electrode. The discharge test is carried out under the discharge condition of 2 mA. Figure 7 It can be seen that when the positive electrode of the battery is an ion intercalation material, when the water content increases, the number of hydrogen ions increases and the discharge performance of the battery improves.

[0061] In one embodiment, the energy storage device is provided with an opening, and the opening is used to exchange moisture with the air. In the technical solution of the present invention, the opening is provided to exchange moisture with the air so that the electrolyte can absorb water from the air, thereby avoiding the situation where the energy storage device fails due to moisture loss.

[0062] In one embodiment, the opening is covered with a hydrophobic layer and / or a semipermeable membrane layer. In the technical solution of the present invention, by providing a hydrophobic layer, the hydrophobicity of the hydrophobic layer can be utilized to prevent the electrolyte in the battery from flowing out of the hydrophobic layer. Preferably, the material of the hydrophobic layer is a hydrophobic sponge; by providing a semipermeable membrane layer, the aqueous electrolyte can be prevented from flowing out of the opening, while at the same time ensuring that water vapor in the air can pass through the semipermeable membrane layer into the energy storage device, so that the electrolyte can absorb water from the air, thereby avoiding the situation where the energy storage device fails due to water loss.

[0063] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0064] Example 1

[0065] This embodiment provides an electrolyte including 5.3 mol urea, 2.6 mol choline, 0.4 mol ZnCl2 and 1.6 mol water.

[0066] Example 2

[0067] This embodiment provides an electrolyte including 5.3 mol urea, 2.6 mol choline, and 2 mol water.

[0068] Example 3

[0069] This embodiment provides an electrolyte solution including 6 mol urea, 3 mol choline, 0.33 mol KAc and 0.66 mol water.

[0070] Example 4

[0071] This embodiment provides an electrolyte solution including 6 mol ethylene glycol, 3 mol ZnCl2 and 1 mol water.

[0072] Comparative Example 1

[0073] This comparative example provides an electrolyte comprising 2 mol of ethylene glycol.

[0074] Comparative Example 2

[0075] This comparative example provides an electrolyte comprising 1 mol urea and 25 mol water.

[0076] Comparative Example 3

[0077] This comparative example provides an electrolyte solution comprising 1 mol of choline and 25 mol of water.

[0078] Comparative Example 4

[0079] This comparative example provides an electrolyte comprising 2 mol of ethylene glycol and 1 mol of choline.

[0080] Comparative Example 5

[0081] This comparative example provides an electrolyte comprising 2 mol urea and 1 mol choline.

[0082] Comparative Example 6

[0083] This comparative example provides an electrolyte solution comprising 1 mol ZnCl2 and 4 mol water.

[0084] Comparative Example 7

[0085] This comparative example provides an electrolyte solution comprising 1 mol ZnCl2 and 4.5 mol water.

[0086] Comparative Example 8

[0087] This comparative example provides an electrolyte comprising 2 mol of ethylene glycol and 1 mol of ZnCl2.

[0088] The components and contents of the electrolytes provided in Examples 1 to 4 and Comparative Examples 1 to 8 are shown in Table 1.

[0089] Table 1 Components and contents of the electrolytes provided in Examples 1 to 4 and Comparative Examples 1 to 8

[0090]

[0091]

[0092] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An aqueous electrolyte, characterized in that The aqueous electrolyte comprises water, a hydrogen bond donor and a hydrogen bond acceptor, and an electrolyte salt; The hydrogen bond donor and the hydrogen bond acceptor form a eutectic agent, and the eutectic agent is used for locking water.

2. The aqueous electrolyte according to claim 1, characterized in that The water locking function of the eutectic is: When the humidity is lower than 10%, the water in the aqueous electrolyte exists in the form of hydrated ions; When the humidity is not less than 10%, the aqueous electrolyte absorbs moisture in the air.

3. The aqueous electrolyte according to claim 1, characterized in that The functional group of the hydrogen bond donor includes: amino, carbonyl or carboxyl. Preferably, the hydrogen bond donor includes at least one of urea, thiourea, amides, polyols, sugars and carboxylic acids. The hydrogen bond acceptor comprises at least one of a quaternary ammonium salt, a zwitterion and a metal salt; The eutectic agent is liquid at 30°C.

4. The aqueous electrolyte according to claim 1, characterized in that The electrolyte salt includes at least one of a halogen zinc salt, a halogen lithium salt, a halogen calcium salt, a potassium carboxylate, and an ammonium carboxylate; The electrolyte salt is dissolved in the eutectic agent.

5. The aqueous electrolyte according to claim 4, characterized in that The electrolyte salt and the eutectic agent have opposite acidity and alkalinity, and the pH value of the aqueous electrolyte is 6-8.

6. An energy storage device, characterized in that: Comprising the aqueous electrolyte according to any one of claims 1 to 5, the energy storage device comprises capacitor energy storage and / or battery energy storage; The chargeable voltage of the energy storage device is not less than 1.23V.

7. The energy storage device according to claim 6, characterized in that: The energy storage device comprises a battery, wherein the positive electrode of the battery is a redox material.

8. The energy storage device according to claim 6, characterized in that: The energy storage device comprises a battery, wherein the positive electrode of the battery is an ion intercalation material, and the intercalation ions of the ion intercalation material comprise hydrogen ions.

9. The energy storage device according to claim 6, characterized in that: The energy storage device is provided with an opening, and the opening is used for exchanging moisture with the air.

10. The energy storage device according to claim 9, characterized in that: The opening is covered with a hydrophobic layer and / or a semi-permeable membrane layer.

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