Ammonium / phosphorus-based electrolyte, preparation method and application of ammonium / phosphorus-based electrolyte in preparation of aqueous zinc-iodine battery

Abstract

The invention provides an ammonium / phosphorus-based electrolyte, and belongs to the technical field of aqueous zinc ion batteries, the electrolyte comprises a zinc salt, water, an organic solvent and an organic salt additive, the zinc salt comprises zinc sulfate, the organic solvent comprises ethylene glycol and / or N, N-dimethylformamide, and the organic salt additive comprises sodium hydroxide and sodium hydroxide. The organic salt additive is prepared from at least one of 3-bromopropyl trimethyl ammonium bromide, tetrapropyl ammonium bromide and methyl triphenyl phosphorus bromide; in the electrolyte, the concentration of the zinc salt is 1-3 mol / L, and the concentration of the organic salt additive is 0.1-0.3 mol / L. The electrolyte can successfully excite and stabilize high-reversible four-electron redox reaction of the zinc-iodine battery from I <-> to I < + >, so that the specific capacity, the electrode potential, the energy density and the cycle performance of the zinc-iodine battery are remarkably improved. The invention also provides a preparation method of the ammonium / phosphorus-based electrolyte and application of the ammonium / phosphorus-based electrolyte in preparation of an aqueous zinc-iodine battery.

Description

Technical Field

[0001] The invention belongs to the technical field of aqueous zinc ion batteries, and particularly relates to an ammonium / phosphorus-based electrolyte, a preparation method and application thereof in preparing aqueous zinc-iodine batteries. Background Art

[0002] Aqueous zinc-ion batteries have attracted widespread attention due to their excellent safety and high energy density, and have shown great application potential in future energy storage systems. However, the specific capacity of the positive electrode of zinc batteries is only 1 / 3 of that of the zinc metal negative electrode, which limits the energy density of zinc-based batteries to a certain extent. Iodine-based positive electrode materials have become the key to improving the performance of zinc-based batteries due to their abundant resources, multivalent states, high capacity and high redox potential.

[0003] The reactions of iodine-based cathodes usually involve I - / I3 - The theoretical capacity is 211 mAh g -1 , the potential is about 1.3 V (vs.Zn 2+ / Zn). It is worth noting that the new four-electron zinc-iodine battery shows superior performance, which adopts a continuous I − / I2 / I + The redox couple enables a higher redox potential (1.07 V / 0.54 V vs. SHE) and doubled theoretical capacity (422 mAh g -1 ). This not only significantly improves the specific capacity, but also 0 Price to I + The theoretical potential of Zn / Zn is 1.75 V (vs. Zn / Zn 2+ ), further improving the energy density.

[0004] However, I2 and I + There is a high barrier for the reversible redox reaction between + It is difficult to exist independently and stably. In addition, the shuttle effect of iodine substances leads to serious capacity decay and poor cycle life of iodine-based positive electrodes. In order to solve these problems, researchers are conducting a series of explorations and attempts. For example, by optimizing electrode materials and structures, the stability and cycle performance of iodine-based positive electrodes can be improved; by introducing catalysts, the I2 and I + By reducing the barrier of redox reaction between the two, the reversibility of the reaction is improved; by designing new diaphragms and electrolytes, the shuttle effect of iodine substances is suppressed and the overall performance of the battery is improved. Summary of the invention

[0005] In order to obtain a high-performance aqueous zinc-iodine battery, the present invention provides an ammonium / phosphorus-based electrolyte that can successfully stimulate and stabilize the zinc-iodine battery from I - To I + The highly reversible four-electron redox reaction can significantly improve the specific capacity, electrode potential, energy density and cycle performance of zinc-iodine batteries.

[0006] The present invention also provides a method for preparing an ammonium / phosphorus-based electrolyte and application of the ammonium / phosphorus-based electrolyte in preparing an aqueous zinc-iodine battery.

[0007] The present invention is achieved through the following technical solutions: The present invention provides an ammonium / phosphorus-based electrolyte, wherein the electrolyte comprises a zinc salt, water, an organic solvent and an organic salt additive, wherein the zinc salt comprises zinc sulfate, the organic solvent comprises ethylene glycol and / or N,N-dimethylformamide, and the organic salt additive comprises at least one of 3-bromopropyltrimethylammonium bromide, tetrapropylammonium bromide and methyltriphenylphosphonium bromide; In the electrolyte, the concentration of the zinc salt is 1 to 3 mol / L, and the concentration of the organic salt additive is 0.1 to 0.3 mol / L.

[0008] Furthermore, in the electrolyte, the volume ratio of the organic solvent to water is (30-70):100.

[0009] Optionally, in the electrolyte, the organic solvent is ethylene glycol, and the organic salt additive is 3-bromopropyltrimethylammonium bromide.

[0010] Optionally, in the electrolyte, the organic solvent is N,N-dimethylformamide, and the organic salt additive is tetrapropylammonium bromide.

[0011] Optionally, in the electrolyte, the organic solvent is N,N-dimethylformamide, and the organic salt additive is methyltriphenylphosphonium bromide.

[0012] Based on the same inventive concept, the present invention provides a method for preparing an ammonium / phosphorus-based electrolyte, the preparation method comprising: dissolving zinc sulfate and an organic salt additive in a mixed solution of water and an organic solvent to obtain an ammonium / phosphorus-based electrolyte; In the mixed solution, the volume ratio of the organic solvent to water is (30-70):100; In the ammonium / phosphorus-based electrolyte, the concentration of zinc sulfate is 1 to 3 mol / L, and the concentration of the organic salt additive is 0.1 to 0.3 mol / L.

[0013] Based on the same inventive concept, the present invention provides an application of an ammonium / phosphorus-based electrolyte in the preparation of an aqueous zinc-iodine battery.

[0014] Based on the same inventive concept, the present invention provides an aqueous zinc-iodine battery, wherein the aqueous zinc-iodine battery contains the above-mentioned ammonium / phosphorus-based electrolyte.

[0015] Based on the same inventive concept, the present invention provides an aqueous zinc-iodine battery, which uses an I2-containing composite material as a positive electrode, zinc metal as a negative electrode, glass fiber as a separator, and the above-mentioned ammonium / phosphorus-based electrolyte as an electrolyte.

[0016] Preferably, the raw materials for preparing the I2-containing composite material include activated carbon, iodine and carbon nanotubes, and the mass ratio of the activated carbon, the iodine and the carbon nanotubes is 10:1:1.

[0017] Based on the same inventive concept, the present invention also provides a symmetrical zinc battery, wherein the symmetrical zinc battery uses zinc metal as the positive electrode and the negative electrode, uses glass fiber as the separator, and uses the above-mentioned ammonium / phosphorus-based electrolyte as the electrolyte.

[0018] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: 1. The present invention discloses an ammonium / phosphorus-based electrolyte, which comprises a zinc salt, deionized water, an organic solvent and an organic salt additive, wherein the organic salt additive comprises at least one of 3-bromopropyltrimethylammonium bromide, tetrapropylammonium bromide and methyltriphenylphosphonium bromide, and the organic salt additive can introduce isohalogen conversion chemistry into a zinc-iodine battery, and successfully stimulate and stabilize the zinc-iodine battery from I by an efficient interhalogen activation strategy. - To I + The highly reversible four-electron redox reaction has greatly improved the specific capacity, electrode potential and cycle performance of zinc-iodine batteries. - As an activator, it promotes I - To I + The four-electron reaction can effectively alleviate kinetic barriers, provide high capacity and energy density, and provide an effective strategy for improving the performance of aqueous zinc-ion batteries.

[0019] 2. The present invention discloses an ammonium / phosphorus-based electrolyte, wherein zinc salt and organic salt additives added to the electrolyte are conventional chemicals, and the raw materials used are cheap and readily available. The preparation method of the electrolyte is simple and can be obtained by a simple dissolution method. When applied to aqueous zinc ion batteries, the electrolyte can exhibit good reversibility, high safety and excellent electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 The charge and discharge curves of the Zn / / I2 full cell assembled with the zinc sulfate electrolyte containing 3-bromopropyltrimethylammonium bromide and ethylene glycol in Example 1 at a current density of 1C; Figure 2 The charge and discharge curve of the Zn / / I2 full battery assembled with the zinc sulfate electrolyte containing methyl triphenyl phosphonium bromide and N,N-dimethylformamide in Example 2 at a current density of 1C; Figure 3 The charge and discharge curve of the Zn / / I2 full cell assembled with the zinc sulfate electrolyte containing tetrapropylammonium bromide and N,N-dimethylformamide in Example 3 at a current density of 1C; Figure 4 It is a charge and discharge curve diagram of the Zn / / I2 full battery assembled with zinc sulfate electrolyte containing zinc bromide and N,N-dimethylformamide in Comparative Example 2 at a current density of 1C; Figure 5 The charge and discharge curve of the Zn / / I2 full battery assembled with zinc sulfate electrolyte containing zinc bromide and ethylene glycol in Comparative Example 3 at a current density of 1C; Figure 6 This is a long cycle comparison diagram of a symmetrical zinc battery assembled using the zinc sulfate electrolyte containing methyl triphenyl phosphonium bromide and N,N-dimethylformamide in Example 2 and the zinc sulfate electrolyte containing zinc bromide in Comparative Example 1 at room temperature 25°C; Figure 7 This is a long cycle comparison diagram of a symmetrical zinc battery assembled using the zinc sulfate electrolyte containing tetrapropylammonium bromide and N,N-dimethylformamide in Example 3 and the zinc sulfate electrolyte containing zinc bromide in Comparative Example 1 at room temperature 25°C; Figure 8 This is a long cycle diagram of a Zn / / I2 full cell assembled with the zinc sulfate electrolyte containing 3-bromopropyltrimethylammonium bromide and ethylene glycol in Example 1 of the present invention and the zinc sulfate electrolyte containing zinc bromide in Comparative Example 1 at a current density of 1C.

[0022] Fig. 9 This is a long cycle diagram of a Zn / / I2 full cell assembled with the zinc sulfate electrolyte containing methyl triphenyl phosphonium bromide and N,N-dimethylformamide in Example 2 of the present invention and the zinc sulfate electrolyte containing zinc bromide in Comparative Example 1 at a current density of 1C.

[0023] Fig.10 This is a long cycle diagram of a Zn / / I2 full cell assembled with the zinc sulfate electrolyte containing tetrapropylammonium bromide and N,N-dimethylformamide in Example 3 of the present invention and the zinc sulfate electrolyte containing zinc bromide in Comparative Example 1 at a current density of 1C. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are used to illustrate the present invention, rather than to limit the present invention.

[0025] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0026] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0027] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0028] The technical principle of the present invention is as follows: The present invention discloses an ammonium / phosphorus-based electrolyte, wherein the electrolyte comprises a zinc salt, water, an organic solvent and an organic salt additive, wherein the zinc salt comprises zinc sulfate, the organic solvent comprises ethylene glycol and / or N,N-dimethylformamide, and the organic salt additive comprises at least one of 3-bromopropyltrimethylammonium bromide, tetrapropylammonium bromide and methyltriphenylphosphonium bromide; In the electrolyte, the concentration of the zinc salt is 1 to 3 mol / L, and the concentration of the organic salt additive is 0.1 to 0.3 mol / L.

[0029] In the electrolyte of the present invention, the role of the organic solvent is to optimize the composition of the organic electrolyte, improve the conductivity of the organic electrolyte, reduce polarization, improve the coulomb efficiency of the battery, and increase the reversibility of the battery cycle.

[0030] The organic solvent is ethylene glycol or N,N-dimethylformamide. Ethylene glycol and N,N-dimethylformamide (DMF) are both important organic chemical raw materials, each with its own unique advantages. Ethylene glycol has good water solubility and a high boiling point, while DMF is a multifunctional solvent with good solubility, high boiling point, thermal stability and chemical stability. Both are cheap and widely used and are common organic solvents.

[0031] The advantage of using 3-bromopropyltrimethylammonium bromide, tetrapropylammonium bromide and methyltriphenylphosphonium bromide as organic salt additives is that all of them contain bromine and have a voltage range of 0.5 to 1.85 V, and all of them can stimulate a four-electron reaction.

[0032] In the electrolyte of the present invention, the concentration of zinc salt is 1 to 3 mol / L. If the concentration of zinc salt is too high: although it can improve the conductivity of the electrolyte and enhance the migration rate of zinc ions, thereby improving the charge and discharge efficiency of the battery, the high concentration of zinc salt may increase the viscosity of the electrolyte, making ion transmission more difficult, which in turn reduces the performance of the battery; in addition, high-concentration electrolytes may aggravate the growth of zinc dendrites, leading to internal short circuits in the battery and shortened cycle life. If the concentration of zinc salt is too low: although it helps to reduce the growth of zinc dendrites and reduce the internal resistance of the battery, thereby improving the cycle stability and safety of the battery, it will cause the conductivity of the electrolyte to decrease, the migration rate of zinc ions to slow down, and affect the charge and discharge performance and energy density of the battery.

[0033] In the electrolyte of the present invention, the concentration of the organic salt additive is 0.1-0.3 mol / L. If it is less than 0.1 mol / L, the organic additive is too little to significantly improve the battery performance. If it is higher than 0.3 mol / L, the organic additive is too much and may cause insolubility.

[0034] Furthermore, in the electrolyte, the volume ratio of the organic solvent to water is (30-70):100.

[0035] In the present invention, the volume ratio of organic solvent to water is (30-70):100. The effects of too low organic solvent concentration are: 1. Decreased ion conductivity: Ion conductivity is one of the key properties of the electrolyte. Too low a concentration will lead to a decrease in the number of ions in the electrolyte, thereby reducing ion conductivity and affecting the charge and discharge performance of the battery.

[0036] 2. Increased internal resistance of the battery: Insufficient electrolyte concentration will increase the internal impedance of the battery, causing the battery to generate more heat during the charging and discharging process and reduce energy efficiency.

[0037] 3. Deterioration of cycle performance: Insufficient electrolyte concentration may accelerate battery aging and reduce the battery cycle life.

[0038] 4. Narrowing of electrochemical window: Low electrolyte concentration may cause its electrochemical window to narrow, thereby limiting the operating voltage range of the battery.

[0039] Effects of excessive organic solvent concentration: 1. Interface stability problem: Too high concentration may form an unstable layer at the interface between the electrode and the electrolyte, affecting the long-term stability of the battery.

[0040] 2. Reduced ion migration number: High concentration of organic solvents may reduce the migration number of ions, thereby affecting the kinetic performance of the battery.

[0041] 3. Increased electrolyte viscosity: Excessively high concentration leads to increased electrolyte viscosity, which is not conducive to the rapid movement of ions, thereby affecting the battery's rate performance.

[0042] 4. Safety issues: High concentrations of organic solvents may increase the safety risks of batteries under extreme conditions, such as thermal runaway.

[0043] 5. Impact on film-forming properties: Too high or too low concentration of organic solvent in the electrolyte may affect the properties of the solid electrolyte interface (SEI) film formed on the electrode surface, thereby affecting the stability and life of the battery.

[0044] In addition, too high an organic additive concentration may increase the cost of the electrolyte and may cause adverse side reactions at high potentials. If the organic additive concentration is too low: although it can reduce the cost of the electrolyte and may reduce the viscosity of the electrolyte, which is beneficial to ion transport, it may lead to insufficient protection of the electrolyte and fail to effectively inhibit the decomposition of the electrolyte and the side reactions of the electrode, resulting in a shortened battery cycle life, reduced coulombic efficiency and reduced safety.

[0045] The following will describe in detail an ammonium / phosphorus-based electrolyte, a preparation method and its application in preparing an aqueous zinc-iodine battery according to the present invention in combination with examples and experimental data.

[0046] The battery performance tests in the following examples and comparative examples were all conducted using the Xinwei battery test system. In order to measure the long cycle time of the symmetrical battery, two polished zinc foils were used as two electrode sheets, the electrolyte prepared in the following examples and comparative examples was used, and the glass fiber was used as a separator to assemble a 2032 button symmetrical battery, and the test was conducted under constant current density and constant time. In order to study the feasibility of the application of additives in actual full batteries, we mixed activated carbon (purchased from Kuraray China Co), iodine (I812016, 99.8%, purchased from Macklin) and carbon nanotubes (G991390, ≥95%, diameter: 20-40nm, length: 1-2μm, purchased from Macklin) in a mass ratio of 10:1:1: and added 1-2 ml of bacterial cellulose dispersion and dissolved in an aqueous solution to prepare a mixed solution, which was then filtered and dried to prepare a working electrode (positive electrode). The electrolyte prepared in the following examples and comparative examples was used, glass fiber was used as a separator, and zinc foil was used as a negative electrode to assemble a 2032 button battery. The test voltage range was 0.5 V-1.85 V vs. Zn / Zn 2+ .

[0047] Example 1 This embodiment provides a method for preparing an ammonium / phosphorus-based electrolyte, which specifically includes: (1) Weigh 1.4378 g of zinc sulfate heptahydrate and 0.1305 g of 3-bromopropyltrimethylammonium bromide powder and dissolve them in a mixed solution of deionized water and ethanol. Add deionized water to make up to 5 ml of the mixed liquid, and stir with a magnetic stirrer to accelerate the dissolution and uniform dispersion. (2) The solution obtained in step (1) is filtered by suction through a microporous filtration membrane (pore size 0.45 μm) to remove insoluble impurities in the solution and obtain an ammonium / phosphorus-based electrolyte.

[0048] In the ammonium / phosphorus-based electrolyte, the volume ratio of deionized water to ethanol is 100:30.

[0049] Example 2 This embodiment provides a method for preparing an ammonium / phosphorus-based electrolyte, which specifically includes: (1) Weigh 1.4378 g of zinc sulfate heptahydrate and 0.3572 g of methyl triphenylphosphonium bromide powder and dissolve them in a mixed solution of deionized water and N,N-dimethylformamide. Add deionized water to make up to 5 ml of the mixed liquid, and stir with a magnetic stirrer to accelerate the dissolution and disperse evenly. (2) The solution obtained in step (1) is filtered by suction through a microporous filtration membrane (pore size 0.45 μm) to remove insoluble impurities in the solution and obtain an ammonium / phosphorus-based electrolyte.

[0050] In the ammonium / phosphorus-based electrolyte, the volume ratio of deionized water to N,N-dimethylformamide is 100:30.

[0051] Example 3 This embodiment provides a method for preparing an ammonium / phosphorus-based electrolyte, which specifically includes: (1) Weigh 1.4378 g of zinc sulfate heptahydrate and 0.3993 g of tetrapropylammonium bromide powder and dissolve them in a mixed solution of deionized water and N,N-dimethylformamide. Add deionized water to make up to 5 ml of the mixed liquid, and stir with a magnetic stirrer to accelerate the dissolution and uniform dispersion. (2) The solution obtained in step (1) is filtered by suction through a microporous filtration membrane (pore size 0.45 μm) to remove insoluble impurities in the solution and obtain an ammonium / phosphorus-based electrolyte.

[0052] In the ammonium / phosphorus-based electrolyte, the volume ratio of deionized water to N,N-dimethylformamide is 100:30.

[0053] Comparative Example 1 This embodiment provides a method for preparing an electrolyte, which specifically includes: 1) Dissolve 0.3378 g zinc bromide and 1.4378 g zinc sulfate heptahydrate in deionized water, add deionized water to make up to 5 ml of the mixed liquid, and stir with a magnetic stirrer to accelerate the dissolution and disperse evenly; 2) The solution obtained in step (1) is filtered by suction through a microporous filter membrane (pore size 0.45 μm) to remove insoluble impurities in the solution, thereby obtaining a zinc sulfate electrolyte containing zinc bromide.

[0054] Comparative Example 2 This embodiment provides a method for preparing an electrolyte, which specifically includes: 1) Dissolve 0.1126 g zinc bromide and 1.4378 g zinc sulfate heptahydrate in a mixed solution of deionized water and N,N-dimethylformamide, add deionized water to make up to 5 ml of the mixed liquid, and stir with a magnetic stirrer to accelerate the dissolution and disperse evenly; 2) The solution obtained in step (1) is filtered by suction through a microporous filter membrane (pore size 0.45 μm) to remove insoluble impurities in the solution and obtain zinc sulfate electrolyte.

[0055] In the zinc sulfate electrolyte, the volume ratio of deionized water to N,N-dimethylformamide is 100:30.

[0056] Comparative Example 3 This embodiment provides a method for preparing an electrolyte, which specifically includes: 1) Dissolve 0.1126 g zinc bromide and 1.4378 g zinc sulfate heptahydrate in a mixed solution of deionized water and ethylene glycol, add deionized water to make up to 5 ml of the mixed liquid, and stir with a magnetic stirrer to accelerate the dissolution and disperse evenly; 2) The solution obtained in step (1) is filtered by suction through a microporous filter membrane (pore size 0.45 μm) to remove insoluble impurities in the solution and obtain zinc sulfate electrolyte.

[0057] In the zinc sulfate electrolyte, the volume ratio of deionized water to ethylene glycol is 100:30.

[0058] Figure 1 The charge and discharge curves of the Zn / / I2 full battery assembled with the zinc sulfate electrolyte containing 3-bromopropyltrimethylammonium bromide and ethylene glycol in Example 1 at a current density of 1C. Figure 1 It can be seen that the added organic additive 3-bromopropyltrimethylammonium bromide can stimulate the four-electron reaction of the zinc-iodine battery, and the capacity can reach about 630mAh / g, which is significantly improved compared to the battery performance assembled with zinc sulfate electrolyte adding zinc bromide and ethylene glycol.

[0059] Figure 2The charge and discharge curves of the Zn / / I2 full battery assembled with zinc sulfate electrolyte containing methyl triphenylphosphonium bromide and N,N-dimethylformamide in Example 2 at a current density of 1C. Figure 2 It can be seen that the added organic additive methyl triphenyl phosphonium bromide can stimulate the four-electron reaction of the zinc-iodine battery, and the capacity can reach about 500 mAh / g, which is significantly improved compared to the battery performance assembled by adding zinc bromide.

[0060] Figure 3 The charge and discharge curves of the Zn / / I2 full battery assembled with the zinc sulfate electrolyte containing tetrapropylammonium bromide and N,N-dimethylformamide in Example 3 at a current density of 1C. Figure 3 It can be seen that the added organic additive tetrapropylammonium bromide can stimulate the four-electron reaction of the zinc-iodine battery, and the capacity can reach about 580mAh / g, which is significantly improved compared to the battery performance assembled by adding zinc bromide.

[0061] Figure 4 The charge and discharge curves of the Zn / / I2 full battery assembled with zinc sulfate electrolyte containing zinc bromide and N,N-dimethylformamide in Comparative Example 2 at a current density of 1C. Figure 4 It can be seen that the battery assembled with the added organic additive zinc bromide cannot stimulate the four-electron reaction of the zinc-iodine battery.

[0062] Figure 5 The charge and discharge curves of the Zn / / I2 full battery assembled with zinc sulfate electrolyte containing zinc bromide and ethylene glycol in Comparative Example 3 at a current density of 1C. Figure 5 It can be seen that the battery assembled with the added organic additive zinc bromide cannot stimulate the four-electron reaction of the zinc-iodine battery.

[0063] Figure 6 This is a long cycle comparison diagram of a symmetrical zinc battery assembled using the zinc sulfate electrolyte containing methyl triphenylphosphonium bromide and N,N-dimethylformamide in Example 2 and the zinc sulfate electrolyte containing zinc bromide in Comparative Example 1 at room temperature 25°C. It can be seen from the figure that after adding the additive, the cycle life of the battery is significantly extended compared to when no additive is added.

[0064] Figure 7 This is a long cycle comparison chart of a symmetrical zinc battery assembled using the zinc sulfate electrolyte containing tetrapropylammonium bromide and N,N-dimethylformamide in Example 3 and the zinc sulfate electrolyte containing zinc bromide in Comparative Example 1 at room temperature 25°C. It can be seen from the figure that after adding the additive, the cycle life of the battery is significantly extended compared to when no additive is added.

[0065] Figure 8The figure is a long cycle diagram of a Zn / / I2 full cell assembled with the zinc sulfate electrolyte containing 3-bromopropyltrimethylammonium bromide and ethylene glycol in Example 1 of the present invention and the zinc sulfate electrolyte containing zinc bromide in Comparative Example 1 at a current density of 1C. It can be clearly seen that in the zinc sulfate electrolyte containing 3-bromopropyltrimethylammonium bromide and ethylene glycol, the assembled full cell exhibits a higher reversible capacity, and after 700 charge and discharge cycles, its discharge capacity can still reach 600 mAh g -1 , its cycle stability showed more significant superiority.

[0066] Fig. 9 The figure is a long cycle diagram of a Zn / / I2 full cell assembled with the zinc sulfate electrolyte containing methyl triphenyl phosphonium bromide and N,N-dimethylformamide in Example 2 of the present invention and the zinc sulfate electrolyte containing zinc bromide in Comparative Example 1 at a current density of 1C. It can be clearly seen that in the zinc sulfate electrolyte containing methyl triphenyl phosphonium bromide and N,N-dimethylformamide, the assembled full cell exhibits a higher reversible capacity, and after 1000 charge and discharge cycles, its discharge capacity can still reach 500 mAh g -1 , its cycle stability showed more significant superiority.

[0067] Fig.10 The figure is a long cycle diagram of a Zn / / I2 full cell assembled with the zinc sulfate electrolyte containing tetrapropylammonium bromide and N,N-dimethylformamide in Example 3 of the present invention and the zinc sulfate electrolyte containing zinc bromide in Comparative Example 1 at a current density of 1C. It can be clearly seen that in the zinc sulfate electrolyte containing tetrapropylammonium bromide and N,N-dimethylformamide, the assembled full cell exhibits a higher reversible capacity, and after 1000 charge and discharge cycles, its discharge capacity can still reach 550 mAh g -1 , its cycle stability showed more significant superiority.

[0068] In summary, the ammonium / phosphorus-based electrolyte prepared by the present invention introduces isohalogen conversion chemistry into zinc-iodine batteries and successfully stimulates and stabilizes the zinc-iodine battery from I - To I + The highly reversible four-electron redox reaction of Br is a promising approach to improve the specific capacity, electrode potential and cycle performance of zinc-iodine batteries. - As an activator, it promotes I - To I +The four-electron reaction can effectively reduce kinetic obstacles, provide high capacity and energy density, and provide an effective strategy for improving the performance of aqueous zinc-ion batteries. This is of great significance for promoting the industrial-scale production of aqueous zinc-ion batteries.

[0069] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article, or apparatus.

[0070] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0071] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. An ammonium / phosphorus-based electrolyte, characterized in that The electrolyte comprises a zinc salt, water, an organic solvent and an organic salt additive, wherein the zinc salt comprises zinc sulfate, the organic solvent comprises ethylene glycol and / or N,N-dimethylformamide, and the organic salt additive comprises at least one of 3-bromopropyltrimethylammonium bromide, tetrapropylammonium bromide and methyltriphenylphosphonium bromide; In the electrolyte, the concentration of the zinc salt is 1 to 3 mol / L, and the concentration of the organic salt additive is 0.1 to 0.3 mol / L.

2. An ammonium / phosphorus-based electrolyte according to claim 1, characterized in that: In the electrolyte, the volume ratio of the organic solvent to water is (30-70):

100.

3. An ammonium / phosphorus-based electrolyte according to claim 1 or 2, characterized in that: In the electrolyte, the organic solvent is ethylene glycol, and the organic salt additive is 3-bromopropyltrimethylammonium bromide.

4. An ammonium / phosphorus-based electrolyte according to claim 1 or 2, characterized in that: In the electrolyte, the organic solvent is N,N-dimethylformamide, and the organic salt additive is tetrapropylammonium bromide.

5. An ammonium / phosphorus-based electrolyte according to claim 1 or 2, characterized in that: In the electrolyte, the organic solvent is N,N-dimethylformamide, and the organic salt additive is methyl triphenyl phosphonium bromide.

6. A method for preparing an ammonium / phosphorus-based electrolyte according to any one of claims 1 to 5, characterized in that: The preparation method comprises: dissolving zinc sulfate and an organic salt additive in a mixed solution of water and an organic solvent to obtain an ammonium / phosphorus-based electrolyte; In the mixed solution, the volume ratio of the organic solvent to water is (30-70):100; In the ammonium / phosphorus-based electrolyte, the concentration of zinc sulfate is 1 to 3 mol / L, and the concentration of the organic salt additive is 0.1 to 0.3 mol / L.

7. Use of an ammonium / phosphorus-based electrolyte as claimed in any one of claims 1 to 5 in the preparation of an aqueous zinc-iodine battery.

8. An aqueous zinc-iodine battery, characterized in that: The aqueous zinc-iodine battery contains an ammonium / phosphorus-based electrolyte according to any one of claims 1-5.

9. An aqueous zinc-iodine battery, characterized in that: The aqueous zinc-iodine battery uses an I2-containing composite material as a positive electrode, zinc metal as a negative electrode, glass fiber as a separator, and an ammonium / phosphorus-based electrolyte as described in any one of claims 1-5 as an electrolyte.

10. The aqueous zinc-iodine battery according to claim 9, characterized in that: The raw materials for preparing the I2-containing composite material include activated carbon, iodine and carbon nanotubes, and the mass ratio of the activated carbon, the iodine and the carbon nanotubes is 10:1:1.

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