High-energy-density aqueous zinc-iodine battery electrolyte and preparation method and application thereof
By using cyano and chlorine-based organic additives in aqueous zinc-iodine batteries and combining low-concentration zinc salts, a high energy density and low-cost zinc-iodine batteries are achieved, which solves the problems of low energy density and high cost, and improves battery performance and stability.
Patent Information
- Application Number
- CN202510523736.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-07-29
AI Technical Summary
The existing zinc-iodine batteries have low energy density and high cost. The high zinc salt concentration leads to a decrease in the zinc ion transmission rate, poor thermal stability of the electrolyte, and many safety problems, making it difficult to commercialize.
Organic substances containing cyano and chlorine groups are used as additives, combined with low concentration zinc salts, and high-energy density aqueous zinc-iodine battery electrolyte is prepared, which increases the energy density and reduces costs through four electron transfer.
The redox of higher valence iodine ions is achieved at low salt concentration, which significantly improves the battery energy density and cycle life, reduces manufacturing costs, and improves the discharge specific capacity and interface stability of zinc-iodine batteries.
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of aqueous zinc-iodine batteries, and in particular to a high-energy-density aqueous zinc-iodine battery electrolyte, a preparation method thereof, and applications thereof. Background Art
[0002] New energy storage technologies are crucial for building new power systems and developing sustainable energy. Portable lithium-ion secondary batteries, as the primary component of energy storage systems, dominate the market. However, lithium-ion battery costs are still constrained by the price of lithium ore, the thermal stability of the carbonate electrolytes they use, and safety issues caused by internal short circuits are rampant. Furthermore, energy density is limited by the graphite anode.
[0003] In order to improve the commercial value of secondary batteries, it is necessary to develop low-cost, thermally stable and high-energy-density aqueous batteries. Redox, achieve two-electron transfer, low theoretical energy density (211mAh g -1 ) limits its commercialization process. At present, some studies have reported that stimulating the redox of higher valence iodine ions (+1, +5, +7) can achieve higher energy density. The redox reaction can achieve four-electron transfer and the energy density reaches 422 mAh g -1 However, the four-electron transfer process still relies on high concentrations of zinc chloride (10-25 mol L -1 ), the manufacturing cost is an order of magnitude away from commercialization. The most common compound of +1 valence iodine ion is iodine monochloride. Replacing the ionic form with a covalent form of chlorine group is feasible for the redox of four electrons (the outer electron orbit of the positive monovalent iodine ion lacks electrons, and the electron-donating group stimulates the redox of high-valence iodine by generating a halogen bond to form an interhalogen compound. The strongest electronegativity of fluorine makes it difficult to donate electrons, while bromine has a larger atomic core, and iodine-iodine homonuclear molecules do not constitute an interhalogen compound. Therefore, chlorine has moderate electronegativity, polarizability and atomic core. In theory, in the interhalogen compound that produces iodine, the chlorine element The required energy barrier is the lowest (Chem. Rev. 2016, 116, 2478-2601; Chem. Eur. J. 2001, 7, 2511-2519). As the key carrier of ion transport in secondary batteries, the electrolyte is closely related to electrochemical performance and cost. Optimizing its composition is an important means to reduce battery costs and increase efficiency. In addition, high concentrations of zinc salts significantly reduce the effective zinc ion transfer rate and electrolyte / electrode contact. Therefore, based on the above considerations, it is urgent to develop an electrolyte additive that can achieve Redox. Summary of the Invention
[0004] In view of this, the present application provides a high-energy-density aqueous zinc-iodine battery electrolyte, a preparation method thereof, and an application thereof. The electrolyte can effectively improve the energy density of the zinc-iodine battery and significantly reduce the manufacturing cost of the zinc-iodine battery, and can effectively overcome the defects of the above-mentioned prior art.
[0005] In a first aspect, the present application provides an aqueous zinc-iodine battery electrolyte with high energy density, comprising an additive, deionized water and a zinc salt, wherein the additive is an organic substance containing a cyano group and a chlorine group.
[0006] Preferably, the additive is selected from at least one of chloroacetonitrile, dichloroacetonitrile, trichloroacetonitrile, 2-chloropropionitrile, 3-chloropropionitrile, 2,3-dichloropropionitrile and 2,2,3-trichloropropionitrile.
[0007] Preferably, the weight percentage of the additive in the electrolyte is 0.1 to 20 wt.%, more preferably, the weight percentage of the additive in the electrolyte is 1 to 10 wt.%.
[0008] Preferably, the zinc salt is selected from at least one of zinc trifluoromethanesulfonate, zinc bis(trifluoromethylsulfonyl)imide, zinc perchlorate, zinc sulfate, zinc acetate, and zinc chloride.
[0009] Preferably, the molar concentration of the zinc salt is 1.0 to 6.0 mol L -1 More preferably, the molar concentration of the zinc salt is 1.0 to 3.0 mol L -1 .
[0010] The second aspect of the present application further provides a method for preparing the above-mentioned high energy density aqueous zinc-iodine battery electrolyte, comprising the following steps:
[0011] A soluble zinc salt as a solute, deionized water as a solvent and additives are mixed in proportion and stirred until the mixture is uniform to obtain an aqueous zinc-iodine battery electrolyte.
[0012] Specifically, the method for preparing the above-mentioned high energy density aqueous zinc-iodine battery electrolyte comprises the following steps:
[0013] Under normal pressure, the additives are added to deionized water containing zinc salt according to a certain proportion, and the mixture is stirred until uniformly mixed to obtain an aqueous zinc-iodine battery electrolyte.
[0014] Preferably, the additive is subjected to high-temperature activated 4 angstrom molecular sieve to remove impurities before use, and its purity is 98-99.999%.
[0015] The third aspect of the present application also provides an aqueous zinc-iodine battery, which includes an iodine-containing positive electrode, a metallic zinc negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte. The electrolyte is the above-mentioned aqueous zinc-iodine battery electrolyte with high energy density.
[0016] Preferably, the separator is made of glass fiber.
[0017] Preferably, the current collector used for the iodine-containing positive electrode is selected from one of a stainless steel mesh, a titanium foil, a graphite paper, a carbon cloth, and a carbon paper. More preferably, the current collector is a carbon paper or a graphite paper.
[0018] It should be noted that the current collector belongs to the positive electrode part and is a substrate for loading iodine substances.
[0019] Compared with the prior art, the present application has the following beneficial effects:
[0020] (1) The present application does not require high-concentration zinc salts. Under ultra-low salt concentration, a small amount of additives can be used to stimulate the redox of higher-valence iodine ions, greatly improving the energy density of the battery and reducing the manufacturing cost of the battery. The discharge specific capacity of the zinc-iodine battery containing the electrolyte of the present application far exceeds 211 mAh g -1 .
[0021] (2) The electrolyte of the present application effectively reduces the interfacial impedance of the zinc negative electrode, significantly improving the cycle life and interfacial stability of the battery.
[0022] (3) The electrolyte of the present application can achieve a four-electron transfer of iodine valence from +1 to -1, effectively improving the battery capacity. The aqueous zinc-iodine battery electrolyte containing cyano and chloro additives can improve the discharge specific capacity and cycle life of the zinc-iodine battery. Description of the Drawings
[0023] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings required for the description of the present application or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0024] Figure 1 It is the cycle performance diagram of the zinc-iodine batteries assembled with the electrolytes prepared in Example 1, Comparative Example 1, Comparative Example 3, and Comparative Example 4;
[0025] Figure 2 It is the rate performance diagram of the zinc-iodine battery assembled with the electrolyte prepared in Example 1;
[0026] Figure 3 It is the impedance diagram of the zinc-iodine batteries assembled with the electrolytes prepared in Example 2 and Comparative Example 1;
[0027] Figure 4 The cyclic voltammetry curves of zinc-iodine batteries assembled with the electrolytes prepared in Example 1 and Comparative Example 2 are shown. DETAILED DESCRIPTION
[0028] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.
[0029] Unless otherwise specified, the experimental methods used in the examples of this application are all conventional methods.
[0030] In the following examples and comparative examples, unless otherwise specified, all raw materials can be purchased commercially or prepared by conventional methods.
[0031] Example 1
[0032] Weigh 72.706g of zinc trifluoromethanesulfonate into a glass reagent bottle, add 100ml of deionized water, and stir on a magnetic stirrer until uniformly mixed to obtain an initial electrolyte. High-temperature activated 4 angstrom molecular sieves remove impurities from chloroacetonitrile. Weigh the resulting initial electrolyte, add 10wt.% chloroacetonitrile, and continue stirring on a magnetic stirrer until uniformly mixed to obtain an additive-containing electrolyte. This electrolyte is labeled 2M ZnOTF + 10wt.% ClAN.
[0033] Example 2
[0034] Weigh 72.706g of zinc trifluoromethanesulfonate into a glass reagent bottle, add 100ml of deionized water, and stir on a magnetic stirrer until uniformly mixed to obtain an initial electrolyte. High-temperature activated 4 angstrom molecular sieves remove impurities from trichloroacetonitrile. Weigh the resulting initial electrolyte, add 10wt.% trichloroacetonitrile, and continue stirring on a magnetic stirrer until uniformly mixed to obtain an additive-containing electrolyte. Label the electrolyte as 2M ZnOTF + 10wt.% Cl3AN.
[0035] Comparative Example 1
[0036] 72.706 g of zinc trifluoromethanesulfonate was weighed and placed in a glass reagent bottle. 100 ml of deionized water was added and stirred on a magnetic stirring table until the mixture was uniformly mixed to obtain an electrolyte without additives. The electrolyte was labeled as 2M ZnOTF.
[0037] Comparative Example 2
[0038] Weigh 57.51 g of zinc sulfate heptahydrate and place it in a glass reagent bottle. Add 100 ml of deionized water and stir in a magnetic stirring table until evenly mixed to obtain an electrolyte without additives. Label the electrolyte as 2M ZnSO4.
[0039] Comparative Example 3
[0040] Weigh 72.706 g of zinc trifluoromethanesulfonate and place it in a glass reagent bottle. Add 100 ml of deionized water and stir in a magnetic stirring table until evenly mixed to obtain an initial electrolyte. Use 4 Å molecular sieve activated at high temperature to remove impurities in acetonitrile. Weigh the obtained initial electrolyte, add 10 wt.% of acetonitrile, and continue to stir in a magnetic stirring table until evenly mixed to obtain an electrolyte with additives. Label the electrolyte as 2M ZnOTF + 10 wt.% AN.
[0041] Comparative Example 4
[0042] Weigh 72.706 g of zinc trifluoromethanesulfonate and place it in a glass reagent bottle. Add 100 ml of deionized water and stir in a magnetic stirring table until evenly mixed to obtain an initial electrolyte. Use 4 Å molecular sieve activated at high temperature to remove impurities in 2-chlorobutane. Weigh the obtained initial electrolyte, add 10 wt.% of 2-chlorobutane, and continue to stir in a magnetic stirring table until evenly mixed to obtain an electrolyte with additives. Label the electrolyte as 2M ZnOTF + 10 wt.% Cl-butane.
[0043] Test Example
[0044] Using metallic zinc as the negative electrode, a glass fiber as the separator, and iodine-loaded carbon paper as the positive electrode, with Swagelok as the battery mold, assemble a Swagelok-type zinc-iodine battery using the electrolytes obtained from the above examples and comparative examples.
[0045] The battery tests were completed on a Blue Power charge-discharge tester, and the electrochemical impedance test (frequency range from 100 kHz to 0.1 Hz) and cyclic voltammetry test (scan rate of 0.1 mV s -1 ) were completed on a Gamry electrochemical workstation.
[0046] Figure 1 The electrochemical performance and cycling stability of the zinc-iodine batteries assembled with the electrolytes prepared in Example 1, Comparative Example 1, Comparative Example 3, and Comparative Example 4 were tested. The test conditions were 1.0 Ag -1 . Example 1 exhibited an initial specific capacity of 310.8 mAh g -1 and a capacity retention rate of 77.4%; Comparative Example l exhibited 219.1 mAh g -1The initial specific capacity and a capacity retention rate of 55.8%. In Comparative Example 3 with a single cyano group, it is unable to promote the achievement of a higher battery capacity; in Comparative Example 4 with a single chlorine group, it cannot effectively stimulate a four-electron redox reaction; therefore, a single group is difficult to play a role. The above results indicate that in Example 1, the combined action of the chlorine group and the cyano group endows the battery with higher electrochemical performance and cycling stability.
[0047] Figure 2 The rate performance of the zinc-iodine battery assembled with the electrolyte prepared in Example 1 was tested at 0.5 Ag -1 ~20.0 Ag -1 at different current densities. At 0.5, 1.0, 2.0, 5.0, 15.0, and 20.0 Ag -1 ultra-high specific capacities of 328.0, 309.7, 265.8, 217.7, 172.9, and 143.3 mAh g -1 were achieved respectively. When the current density returned to 1 Ag -1 , the discharge specific capacity could still reach 299.3 mAh g -1 . It was proved that the zinc-iodine battery assembled with the electrolyte prepared in Example 1 had good rate performance.
[0048] Figure 3 The impedance diagrams of Example 2 and Comparative Example 1 were tested. It can be seen that Example 2 had lower charge transfer impedance and SEI interface impedance, indicating the beneficial effect of the additive on improving the interface stability.
[0049] Figure 4 The cyclic voltammetry curves of the zinc-iodine batteries assembled with the electrolytes prepared in Example 1 and Comparative Example 2 were tested on an electrochemical workstation. In Example 1, two pairs of redox peaks appeared obviously, indicating the reversible conversion of iodine valence from +1 to -1 and the effective realization of four-electron transfer. In Comparative Example 2, only one pair of redox peaks appeared, indicating that the iodine valence only underwent a reversible conversion from 0 to -1, which was a two-electron transfer for a traditional zinc-iodine battery.
[0050] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. An aqueous zinc-iodine battery electrolyte with high energy density, characterized in that, It includes an additive, deionized water and a zinc salt, and the additive is an organic compound containing a cyano group and a chloro group.
2. The aqueous zinc-iodine battery electrolyte with high energy density according to claim 1, wherein The additive is selected from at least one of chloroacetonitrile, dichloroacetonitrile, trichloroacetonitrile, 2-chloropropionitrile, 3-chloropropionitrile, 2,3-dichloropropionitrile, 2,2,3-trichloropropionitrile.
3. The aqueous zinc-iodine battery electrolyte with high energy density according to claim 1, characterized in that, The weight percentage of the additive in the electrolyte is 0.1-20 wt.%.
4. The aqueous zinc-iodine battery electrolyte with high energy density according to claim 1, characterized in that, The zinc salt is selected from at least one of zinc trifluoromethanesulfonate, zinc bis(trifluoromethylsulfonyl)imide, zinc perchlorate, zinc sulfate, zinc acetate, zinc chloride.
5. The aqueous zinc-iodine battery electrolyte with high energy density according to claim 1, characterized in that, The molar concentration of the zinc salt is 1.0 to 6.0 mol / L -1 .
6. A method for preparing an aqueous zinc-iodine battery electrolyte with high energy density according to any one of claims 1-5, characterized in that, It includes the following steps: Mix a soluble zinc salt as a solute, deionized water as a solvent and an additive in proportion, and stir until evenly mixed to obtain an aqueous zinc-iodine battery electrolyte.
7. The preparation method of the aqueous zinc-iodine battery electrolyte with high energy density according to claim 6, characterized in that, Impurities of the additive are removed by 4A molecular sieve activated at high temperature before use, and its purity is 98-99.999%.
8. A water-based zinc-iodine battery, comprising an iodine-containing positive electrode, a metallic zinc negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte, characterized in that, The electrolyte is the high-energy-density aqueous zinc-iodine battery electrolyte according to any one of claims 1-5.
9. The aqueous zinc-iodine battery according to claim 8, wherein, The separator is made of glass fiber.
10. The aqueous zinc-iodine battery according to claim 8, characterized in that, The current collector used for the iodine-containing positive electrode is selected from one of a stainless steel mesh, a titanium foil, a graphite paper, a carbon cloth, and a carbon paper.