A high energy density aqueous zinc-based dual-halogen battery

Abstract

The present invention discloses a high-energy-density aqueous zinc-based dual-halogen battery. This battery uses a carbon material as the positive electrode, a metal zinc foil as the negative electrode, and the electrolyte is a hydrated eutectic electrolyte formed by three halogen salts, namely zinc chloride, choline chloride, and zinc bromide. The unique solvation structure and the limitation of the water molecule activity of the hydrated eutectic electrolyte effectively achieve the fixation of bromine and chlorine, enabling highly reversible redox reactions of bromine and chlorine halogen anions during the charge and discharge process, and a stable deposition / stripping reaction of zinc ions occurs at the negative electrode. The high-energy-density aqueous zinc-based dual-halogen battery provided by the present invention has the characteristics of large discharge capacity, high output voltage, high energy density, long service life, low cost, and good safety, and is suitable for large-scale energy storage applications.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and specifically, relates to a high energy density aqueous zinc-based dual-halogen battery. Background Art

[0002] Lithium-ion secondary batteries have been widely used in portable electronic devices, electric vehicles, and large-scale energy storage fields due to their high energy density and long cycle life. However, the lithium reserve crisis and the safety hazards brought by organic electrolytes have forced people to seek and develop new secondary battery technologies with high safety, environmental friendliness, and low cost. Zinc is rich in resources, low in cost, high in capacity, and environmentally friendly. Therefore, aqueous zinc-based batteries are considered to be a promising new electrochemical system in the next generation of secondary battery systems. However, at present, the energy density of aqueous zinc-based secondary batteries is relatively low and still difficult to meet the application requirements.

[0003] The energy density of a battery mainly depends on two key performance aspects: output voltage and specific capacity. For aqueous zinc-based secondary batteries, since the redox potential of the negative electrode zinc is relatively stable and the specific capacity is high, therefore, improving the working potential and discharge specific capacity of the positive electrode material is the key to enhancing the energy density of the battery. At present, the positive electrode materials of aqueous zinc-based secondary batteries mainly include inorganic materials such as metal oxides, Prussian blue derivatives, and polyanion-type compounds, as well as quinone-based organic positive electrode materials. However, the above electrode materials are all insertion-type electrode materials based on zinc cation carriers, not only with low energy density, but also with poor battery cycle life due to structural distortion.

[0004] Halogen is an element widely present in nature and can reversibly convert between ionic and elemental states to gain and lose electrons. Especially under ideal conditions, based on the standard potential and theoretical capacity of the Br 0 / Br - redox reaction are 1.08 V (Vs. standard hydrogen electrode potential) and 335 mAh / g, while the redox process of Cl 0 / Cl - is as high as 1.36 V and 756 mAh / g. When matched with the redox reaction of the zinc metal negative electrode Zn 2+ / Zn, the discharge voltage of the formed zinc-halogen battery can reach 1.8 V (zinc bromine) and 2.08 V (zinc chlorine). Therefore, zinc-based batteries based on halogen conversion chemical reactions occurring at the positive electrode exhibit the advantages of high potential and high capacity.

[0005] However, the intermediate product after the halogen oxidation reaction, i.e., polyhalide, will irreversibly dissolve into the electrolyte and even shuttle to the negative electrode, resulting in problems such as low Coulombic efficiency, poor reversibility, and serious self-discharge of the battery. Recently, Wang Chunsheng et al. used a halogen + graphite composite cathode, enabling the halogen atoms generated by the oxidation of lithium chloride and lithium bromide in the cathode to be embedded in the graphite. The assembled aqueous lithium-ion battery has a reversible capacity of 243 mAh / g and an energy density exceeding 300 Wh / kg (Nature 2019(569)245-250). However, this new electrochemical system requires the use of a high-concentration aqueous solution of lithium bis(trifluoromethanesulfonyl)imide and lithium trifluoromethanesulfonate, with a high electrolyte cost and cannot be used as an electrolyte for zinc-based batteries. So far, based on the existing aqueous zinc-based battery electrolytes such as zinc trifluoromethanesulfonate and zinc sulfate, the reversible reaction of the redox of halogen anions in zinc-based batteries still cannot be achieved. Given the great application advantages of the battery based on the halogen redox conversion reaction, such as high capacity, high output voltage, and high energy density, it is of great significance to develop a zinc-based battery electrolyte and a cathode material that can support a highly reversible halogen conversion reaction, which is also the key to improving the energy density of aqueous zinc-based batteries. Summary of the Invention

[0006] Aiming at the problem of low energy density of existing aqueous secondary zinc-based batteries, the present invention aims to provide a high-energy-density aqueous zinc-based dual-halogen battery, which has the advantages of low cost, large discharge capacity, high output voltage, high energy density, and long cycle life.

[0007] To solve the above technical problems, the technical solutions provided by the present invention are as follows:

[0008] A high-energy-density aqueous zinc-based dual-halogen battery, which comprises a carbon material as the positive electrode, a metal zinc foil as the negative electrode, an aqueous solution formed by zinc chloride, choline chloride, and zinc bromide as the electrolyte, and a separator for separating the positive and negative electrodes.

[0009] As a limitation of the present invention, the carbon material is one of Ketjen black, activated carbon, or mesoporous carbon.

[0010] Due to its small particle size, large specific surface area, and appropriate pore volume, the carbon material of the present invention is conducive to the stable adsorption and conversion of bromine and chlorine anion carriers, and even the embedding into the localized graphite layer structure, showing a strong binding ability to the active substances, making the reaction highly reversible, and at the same time having the characteristics of low cost.

[0011] As the second limitation of the present invention, the electrolyte is an aqueous solution formed by zinc chloride, choline chloride, and zinc bromide in a mass molar concentration ratio of (80-100)m:(40-50)m:(4-6)m, that is, the mass molar concentration of zinc chloride is not less than 80m and not higher than 100m; the mass molar concentration of choline chloride is not less than 40m and not higher than 50m, and the mass molar concentration of zinc bromide is not less than 4m and not higher than 6m.

[0012] Specifically, when the concentrations of the two chlorides are lower than 80m:40m, the energy density of the battery decreases and the Coulomb efficiency is poor; when the concentrations of the two chlorides are higher than 100m:50m, the ion mobility becomes low and the charge-discharge polarization of the battery increases significantly. The concentration ratio range of zinc bromide in this electrolyte is 4m-6m, that is, the molar ratio of chlorine / bromine (n Cl / n Br ) in the electrolyte ranges from 16.7 to 31.25. The molar ratio of chlorine / bromine in the electrolyte determines the specific capacity of the reversible conversion reaction between bromine and chlorine anions. When zinc chloride, choline chloride, and zinc bromide are mixed according to the molar concentration ratio, when the concentration ratio of zinc bromide is lower than 4m, the capacity contribution of the reversible chlorine conversion reaction increases, but the total discharge capacity decreases and the energy density of the battery decreases; when the concentration ratio of zinc bromide is higher than 6m, the capacity contribution of the reversible bromine conversion reaction increases, but the average voltage of the battery decreases and the energy density of the battery decreases.

[0013] Preferably, the electrolyte is an aqueous solution formed by zinc chloride, choline chloride, and zinc bromide in a mass molar concentration ratio of 80m:40m:5m.

[0014] As the third limitation of the present invention, the mass molar concentration ratio of zinc chloride and choline chloride in the electrolyte is 2:1.

[0015] When zinc chloride and choline chloride are mixed in this ratio, a stable complex ion structure can be formed in the electrolyte and the thermodynamic properties are stable; when the mass molar concentration ratio of zinc chloride to choline chloride is greater than or less than 2:1, the complex ion structure formed in the electrolyte is unstable, resulting in the inability of the metal salt to dissolve and the failure to form a eutectic system.

[0016] The present invention also provides a preparation method for a high-energy density aqueous zinc-based dual-halogen battery, which is carried out in the following order of steps:

[0017] (1) Mix carbon materials and a binder in a mass ratio of (8-9):(1-2), disperse them in an organic solvent to prepare a slurry, roll the slurry into a self-supporting film or coat it on a current collector, and cut it into a positive electrode plate after drying.

[0018] (2) Dissolve zinc chloride, choline chloride, and zinc bromide in deionized water respectively to prepare an electrolyte.

[0019] (3)Separate the above-prepared positive electrode sheet and the negative electrode zinc foil with a separator, place them in a battery case, then inject an electrolyte solution, and encapsulate the battery to assemble a water-based zinc-based dual-halogen battery.

[0020] As a limitation of the preparation method of the present invention, in step (1), the binder is one of polyvinylidene fluoride or polytetrafluoroethylene; the organic solvent is one of N-methylpyrrolidone or isopropyl alcohol; the current collector is one of titanium foil or titanium mesh;

[0021] As the second limitation of the preparation method of the present invention, in step (3), the separator is a glass fiber membrane separator.

[0022] A high-energy-density water-based zinc-based dual-halogen battery provided by the present invention, during the charging process of the battery, conversion reactions of bromine and chlorine halogen anions occur successively at the positive electrode, and deposition reaction of zinc cations occurs at the negative electrode, and a reversible process occurs during discharging. The electrolyte is a hydrated eutectic electrolyte of three halogenated salts, zinc chloride, choline chloride, and zinc bromide. Among them, choline chloride can provide more chloride ions, enabling bromine and chloride ions to form zinc halogen complex anions, thereby greatly increasing the solubility of zinc halide salts in aqueous solution and forming a new type of water-based double-halide eutectic solution. On the one hand, the mass and volume of the solute in this water-based electrolyte are much higher than those of the solvent, which not only greatly reduces the water activity in the electrolyte, but also the zinc halogen complex anion structure effectively binds the activity of water in the solvent shell structure, thereby significantly inhibiting the formation of polyhalides. On the other hand, chloride ions, bromide ions, and water molecules form a stable coordination structure [ZnCl n-m Br n (OH2) m 2-n with zinc ions, and also reduces the non-free halogen anions, which also effectively inhibits the formation and irreversible dissolution or even shuttling of polyhalides to a certain extent. In addition, the increase in anion concentration also reduces its redox potential to a certain extent, enabling chlorine to stably undergo an oxidation reaction and form an interhalogen compound BrCl with bromine atoms, significantly enhancing the redox reversibility of anions.

[0023] As a whole, the above preparation method is closely related and inseparable among each step, and they jointly determine the performance of the water-based zinc battery.

[0024] Due to the adoption of the above technical solution, compared with the prior art, the technical progress achieved by the present invention is as follows:

[0025] 1. The water-based zinc-halogen battery provided by the present invention uses a zinc halide salt-containing electrolyte solution, which is a hydrated eutectic solution. The unique solvation structure of this hydrated eutectic electrolyte, that is, chloride ions, bromide ions, and water molecules form a stable coordination structure [ZnCl n-m ​Br n (OH2) m 2-n , the limitations on the activity of non-free halogen anions and water molecules effectively inhibit the formation of polyhalides and irreversible dissolution or even shuttling, achieve bromine and chlorine fixation, enable highly reversible redox reactions of bromine and chlorine halogen anions during charge and discharge processes, and result in stable deposition / stripping reactions of zinc ions at the negative electrode. Moreover, the ion migration rate is also relatively high.

[0026] 2. The aqueous zinc dual-halogen battery provided by the present invention has the characteristics of high capacity, high output voltage, high energy density, and good cycle stability, showing excellent electrochemical performance. The discharge capacity of this novel aqueous zinc dual-halogen battery is not less than 430 mAh / g at a current density of 100 mA / g, the discharge voltage of the battery is not less than 1.5 V, the energy density is not less than 700 Wh / kg (based on the mass of the carbon positive electrode), and the discharge specific capacity still remains 400 mAh / g after 100 cycles at a current density of 100 mA / g.

[0027] 3. The aqueous zinc dual-halogen battery provided by the present invention uses low-cost materials and a novel hydrated eutectic electrolyte, which is lower in price and environmentally friendly compared to the electrolytes of existing aqueous zinc-based batteries. The assembled aqueous zinc-based dual-halogen battery has the characteristics of high energy density, long service life, low cost, and good safety, and has broad application prospects in large-scale energy storage of renewable energy such as consumer batteries, rail transit, solar energy, and wind energy power generation.

[0028] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings of the specification. Description of the Drawings

[0029] Figure 1 It is the charge-discharge curve diagram of the Ketjen black / / zinc battery in Example 1 in an electrolyte of 80m:40m:4m at a current density of 100 mA / g (the specific capacity is calculated based on the mass of the Ketjen black positive electrode material);

[0030] Figure 2 It is the charge-discharge curve diagram of the Ketjen black / / zinc battery in Example 2 in an electrolyte of 80m:40m:5m at a current density of 100 mA / g (the specific capacity is calculated based on the mass of the Ketjen black positive electrode material);

[0031] Figure 3 It is the charge-discharge curve diagram of the Ketjen black / / zinc battery in Example 3 in an electrolyte of 80m:40m:6m at a current density of 100 mA / g (the specific capacity is calculated based on the mass of the Ketjen black positive electrode material);

[0032] Figure 4 ​Charge-discharge curve of Ketjen black / / zinc battery in Example 4 at a current density of 100 mA / g in the electrolyte of 100m:50m:4m (specific capacity calculated based on the mass of Ketjen black cathode material);

[0033] Figure 5 Charge-discharge curve of Ketjen black / / zinc battery in Example 5 at a current density of 100 mA / g in the electrolyte of 100m:50m:6m (specific capacity calculated based on the mass of Ketjen black cathode material);

[0034] Figure 6 Charge-discharge curve of Ketjen black / / zinc battery in Example 6 at a current density of 100 mA / g in the electrolyte of 90m:45m:5m (specific capacity calculated based on the mass of Ketjen black cathode material);

[0035] Figure 7 Charge-discharge curve of activated carbon / / zinc battery in Example 7 at a current density of 100 mA / g in the electrolyte of 80m:40m:5m (specific capacity calculated based on the mass of activated carbon cathode material);

[0036] Figure 8 Charge-discharge curve of mesoporous carbon / / zinc battery in the example at a current density of 100 mA / g in the electrolyte of 80m:40m:5m (specific capacity calculated based on the mass of ordered mesoporous carbon cathode material);

[0037] Figure 9 Charge-discharge curve cyclic stability diagram of Ketjen black / / zinc battery in Example 2 at a current density of 100 mA / g in the electrolyte of 80m:40m:5m (specific capacity calculated based on the mass of Ketjen black cathode material);

[0038] Figure 10 Charge-discharge curve of Ketjen black / / zinc battery in Comparative Example 1 at a current density of 100 mA / g in the electrolyte of 60m:30m:5m (specific capacity calculated based on the mass of Ketjen black cathode material);

[0039] Figure 11 Charge-discharge curve of Ketjen black / / zinc battery in Comparative Example 2 at a current density of 100 mA / g in the electrolyte of 120m:60m:4m (specific capacity calculated based on the mass of Ketjen black cathode material). Detailed implementation mode

[0040] The reagents used in the following examples can be purchased from existing commercially available reagents without special instructions. The preparation methods and testing methods used in the following examples are all existing methods without special instructions. The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0041] Example 1

[0042] (1) Mix Ketjen black and polytetrafluoroethylene in a mass ratio of 8:2, disperse them in isopropanone to prepare a slurry, roll the slurry into a self-supporting film, dry it and cut it into a positive electrode sheet;

[0043] (2) Dissolve zinc chloride, choline chloride and zinc bromide in deionized water to prepare an electrolyte with a mass molar concentration ratio of 80m:40m:4m;

[0044] (3) Separate the positive electrode sheet and the negative electrode zinc foil prepared above with a diaphragm, put them into a battery case, then inject the electrolyte, encapsulate the battery, and assemble it into an aqueous zinc dual-halogen battery.

[0045] Example 2

[0046] (1) Mix Ketjen black and polytetrafluoroethylene in a mass ratio of 8:2, disperse them in isopropanone to prepare a slurry, roll the slurry into a self-supporting film, dry it and cut it into a positive electrode sheet;

[0047] (2) Dissolve zinc chloride, choline chloride and zinc bromide in deionized water to prepare an electrolyte with a mass molar concentration ratio of 80m:40m:5m;

[0048] (3) Separate the positive electrode sheet and the negative electrode zinc foil prepared above with a diaphragm, put them into a battery case, then inject the electrolyte, encapsulate the battery, and assemble it into an aqueous zinc dual-halogen battery.

[0049] Example 3

[0050] (1) Mix Ketjen black and polytetrafluoroethylene in a mass ratio of 9:1, disperse them in isopropanone to prepare a slurry, roll the slurry into a self-supporting film, dry it and cut it into a positive electrode sheet;

[0051] (2) Dissolve zinc chloride, choline chloride and zinc bromide in deionized water to prepare an electrolyte with a mass molar concentration ratio of 80m:40m:6m;

[0052] (3) Separate the positive electrode sheet and the negative electrode zinc foil prepared above with a diaphragm, put them into a battery case, then inject the electrolyte, encapsulate the battery, and assemble it into an aqueous zinc dual-halogen battery.

[0053] Example 4

[0054] (1) Mix Ketjen black and polytetrafluoroethylene in a mass ratio of 8.5:1.5, disperse them in isopropanone to prepare a slurry, roll the slurry into a self-supporting film, dry it and cut it into a positive electrode sheet;

[0055] (2) Dissolve zinc chloride, choline chloride and zinc bromide in deionized water to prepare an electrolyte with a mass molar concentration ratio of 100m:50m:4m;

[0056] (3) Separate the above-prepared positive electrode sheet and negative electrode zinc foil with a separator, place them in a battery case, then inject the electrolyte, and encapsulate the battery to assemble an aqueous zinc dual-halogen battery.

[0057] Example 5

[0058] (1) Mix Ketjen black and polytetrafluoroethylene in a mass ratio of 9:1 and disperse them in isopropanone to prepare a slurry. Roll the slurry into a self-supporting film, dry it, and cut it into a positive electrode sheet.

[0059] (2) Dissolve zinc chloride, choline chloride, and zinc bromide in deionized water to prepare an electrolyte with a molality ratio of 100m:50m:6m.

[0060] (3) Separate the above-prepared positive electrode sheet and negative electrode zinc foil with a separator, place them in a battery case, then inject the electrolyte, and encapsulate the battery to assemble an aqueous zinc dual-halogen battery.

[0061] Example 6

[0062] (1) Mix Ketjen black and polyvinylidene fluoride in a mass ratio of 9:1 and disperse them in N-methylpyrrolidone to prepare a slurry. Coat the slurry on a titanium foil current collector, dry it, and cut it into a positive electrode sheet.

[0063] (2) Dissolve zinc chloride, choline chloride, and zinc bromide in deionized water to prepare an electrolyte with a molality ratio of 90m:45m:5m.

[0064] (3) Separate the above-prepared positive electrode sheet and negative electrode zinc foil with a separator, place them in a battery case, then inject the electrolyte, and encapsulate the battery to assemble an aqueous zinc dual-halogen battery.

[0065] Example 7

[0066] (1) Mix activated carbon and polyvinylidene fluoride in a mass ratio of 8:2 and disperse them in N-methylpyrrolidone to prepare a slurry. Coat the slurry on a titanium mesh current collector, dry it, and cut it into a positive electrode sheet.

[0067] (2) Dissolve zinc chloride, choline chloride, and zinc bromide in deionized water to prepare an electrolyte with a molality ratio of 80m:40m:5m.

[0068] (3) Separate the above-prepared positive electrode sheet and negative electrode zinc foil with a separator, place them in a battery case, then inject the electrolyte, and encapsulate the battery to assemble an aqueous zinc dual-halogen battery.

[0069] Example 8

[0070] (1) Mesoporous carbon and polytetrafluoroethylene were mixed at a mass ratio of 9:1 and dispersed in isopropanone to prepare a slurry. The slurry was rolled into a self-supporting film, dried and cut into positive electrode sheets;

[0071] (2) Zinc chloride, choline chloride and zinc bromide were dissolved in deionized water to prepare an electrolyte with a molality ratio of 80m:40m:5m;

[0072] (3) The positive electrode sheet and the negative electrode zinc foil prepared above were separated by a separator, placed in a battery case, and then the electrolyte was injected, and the battery was encapsulated to assemble an aqueous zinc dual-halogen battery.

[0073] Comparative Example 1

[0074] (1) Ketjen black and polytetrafluoroethylene were mixed at a mass ratio of 9:1 and dispersed in isopropanone to prepare a slurry. The slurry was rolled into a self-supporting film, dried and cut into positive electrode sheets;

[0075] (2) Zinc chloride, choline chloride and zinc bromide were dissolved in deionized water to prepare an electrolyte with a molality ratio of 60m:30m:5m;

[0076] (3) The positive electrode sheet and the negative electrode zinc foil prepared above were separated by a separator, placed in a battery case, and then the electrolyte was injected, and the battery was encapsulated to assemble an aqueous zinc dual-halogen battery.

[0077] Comparative Example 2

[0078] (1) Ketjen black and polytetrafluoroethylene were mixed at a mass ratio of 9:1 and dispersed in isopropanone to prepare a slurry. The slurry was rolled into a self-supporting film, dried and cut into positive electrode sheets;

[0079] (2) Zinc chloride, choline chloride and zinc bromide were dissolved in deionized water to prepare an electrolyte with a molality ratio of 120m:60m:4m;

[0080] (3) The positive electrode sheet and the negative electrode zinc foil prepared above were separated by a separator, placed in a battery case, and then the electrolyte was injected, and the battery was encapsulated to assemble an aqueous zinc dual-halogen battery.

[0081] The batteries prepared in Examples 1-8 (test results are shown in Figures 1 to 9 ) and Comparative Examples 1-2 (test results are shown in Figures 10 to 11 ) were subjected to charge and discharge tests using a CT3001A battery testing device produced by Wuhan Blue Electronic Co., Ltd., and the existing method was adopted during the testing process.

[0082] From the attached Figures 1 to 9It can be seen that for the aqueous zinc dual-halogen battery assembled with Ketjen black, activated carbon, and mesoporous carbon as the cathode material and a hydrated eutectic solution formed by zinc chloride, choline chloride, and zinc bromide as the electrolyte, there are two charge-discharge platforms in the charge-discharge curve. Among them, the low platform and the high platform respectively represent the adsorption, conversion, or insertion based on Br 0 / Br - and Cl 0 / Cl - . The discharge voltage of the battery is not lower than 1.5 V, the discharge capacity based on the carbon cathode material is not lower than 430 mAh / g, the energy density is not lower than 700 Wh / kg, the discharge specific capacity based on the carbon material and carriers is not lower than 200 mAh / g, and the energy density is not lower than 300 Wh / kg; under the condition of a small current of 100 mA / g, the discharge specific capacity of the battery still remains 400 mAh / g after 100 cycles.

[0083] As can be seen from Figures 10 to 11 , when the concentrations of the two chloride salts in the electrolyte are 60 m:40 m:5 m, the discharge capacity of the battery decreases significantly, only being 395 mAh / g, the energy density of the battery decreases to 592 Wh / kg, and the Coulomb efficiency is poor; when the concentrations of the two chlorides are higher than 120 m:60 m:4 m, the ion mobility becomes low, the charge-discharge polarization of the battery increases significantly, and the average charge-discharge voltage difference expands by ~0.2 V compared with Examples 1-8.

[0084] Comparative Example 3

[0085] In this example, a series of explorations were carried out on the material compatibility of the electrolyte of the aqueous zinc dual-halogen battery. The preparation process of the aqueous zinc dual-halogen battery is similar to that of Example 1, with the only difference being: the composition of the electrolyte is different. Specifically as follows:

[0086]

[0087] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-energy-density aqueous zinc-based dual-halogen battery, characterized in that, Using a carbon material as the positive electrode, a metallic zinc foil as the negative electrode, and an electrolyte composed of zinc chloride, choline chloride, zinc bromide, and deionized water, where chloride ions, bromide ions, and water molecules form a stable coordination structure with zinc ions [ZnCl n-m Br n (OH2) m 2-n , and a separator for separating the positive and negative electrodes;​ The mass molar concentration ratio of zinc chloride, choline chloride and zinc bromide in the electrolyte is (80 - 100):(40 - 50):(4 - 6); The mass molar concentration ratio of zinc chloride and choline chloride in the electrolyte is 2:

1.

2. The high-energy-density aqueous zinc-based dual-halogen battery according to claim 1, characterized in that The carbon material is one of Ketjen black, activated carbon or mesoporous carbon.

3. The high-energy-density aqueous zinc-based dual-halogen battery according to claim 1, wherein The mass molar concentration ratio of zinc chloride, choline chloride and zinc bromide in the electrolyte is 80:40:

5.

4. The preparation method of a high energy density aqueous zinc-based dual-halogen battery according to any one of claims 1-3, characterized in that, The following steps are carried out in sequence: (1) Mix the carbon material and the binder in a mass ratio of (8 - 9):(1 - 2), disperse them in an organic solvent to prepare a slurry, roll the slurry into a self-supporting film or coat it on a current collector, dry it and cut it into a positive electrode sheet; (2) Dissolve zinc chloride, choline chloride and zinc bromide in deionized water respectively to prepare an electrolyte; (3) Separate the positive electrode sheet and the negative electrode zinc foil prepared above with a separator, put them into a battery case, then inject the electrolyte, encapsulate the battery, and assemble a water-based zinc-based dual-halogen battery.

5. The preparation method of a high-energy density aqueous zinc-based dual-halogen battery according to claim 4, characterized in that, In step (1), the binder is one of polyvinylidene fluoride or polytetrafluoroethylene; the organic solvent is one of N-methylpyrrolidone or isopropanol; the current collector is one of titanium foil or titanium mesh.

6. The preparation method of a high energy density aqueous zinc-based dual-halogen battery according to claim 4, wherein In step (3), the separator is a glass fiber membrane separator.

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