High-energy-density seawater-based zinc-iodine battery electrolyte and preparation method and application thereof
By using seawater-based electrolyte in zinc-iodine batteries and adding bromoacetonitrile, the high-valent redox reaction of halogen ions is stimulated, and the problems of low energy density and high cost of zinc-iodine batteries are solved, and a high energy density and low cost battery system is realized.
Patent Information
- Application Number
- CN202510588839.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-08
- Publication Date
- 2025-08-01
AI Technical Summary
The existing zinc-iodine batteries have low energy density and high manufacturing costs, making it difficult to meet the high energy needs of equipment such as electric vehicles and mobile phones.
Seawater is used as the base solvent and bromoacetonitrile is added as an additive to prepare a high-energy density seawater-based zinc-iodine battery electrolyte to stimulate the high-valent redox reaction of halogen ions and realize six-electron transfer.
It significantly improves the energy density of zinc-iodine batteries to 3 times the initial value, reduces manufacturing costs, has good electrochemical performance and easy manufacturing.
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Figure CN120413823A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of batteries, and in particular to a seawater-based zinc-iodine battery electrolyte with high energy density, a preparation method thereof, and an application thereof. Background Art
[0002] The development of energy storage technology lags far behind that of other electronic components, which is specifically reflected in the "range anxiety" of electric vehicles and the repeated charging in daily use of mobile phones. Developing a battery system with higher energy density helps to break this dilemma.
[0003] The classic zinc-iodine battery uses The redox between can achieve a two-electron redox of one iodine molecule, and the theoretical energy density is 211 mAh g -1 , which has no significant advantage compared with the commercially available ternary cathode material NCM523 (the theoretical energy density is about 200 mAh g -1 ). Halide ions have chemical properties of multiple valence states (-1, 0, +1, +5, +7). Activating high-valence halide ions and realizing stable redox are important means to improve the energy density of aqueous batteries. For example, using The redox between can achieve a four-electron redox of one iodine molecule, and the theoretical energy density is 422 mAh g -1 , and using the redox between iodine valence states and the redox between bromine valence states can achieve a six-electron redox of halogen species, and the theoretical energy density is 633 mAh g -1 . Therefore, the six-electron transfer zinc-iodine battery has important commercial value.
[0004] On the other hand, China is rich in marine resources. Replacing deionized water and ultrapure water with filtered seawater as the basic solvent of the aqueous battery is crucial for reducing the manufacturing cost of the battery. In addition, sodium ions in seawater can improve the zinc ion deposition behavior, and halogen compounds formed by chloride ions and bromine, iodine and other ions can improve the stability of high-valence halide ions. Therefore, based on the above considerations, it is necessary to develop an electrolyte additive that can achieve the redox between iodine valence states and the redox between bromine valence states in a seawater environment. Summary of the Invention
[0005] In view of this, this application provides a seawater-based zinc-iodine battery electrolyte with high energy density, a preparation method thereof, and an application thereof. This electrolyte can activate higher-valence halide ions and significantly reduce the manufacturing cost of zinc-iodine batteries, and can effectively overcome the defects existing in the above-mentioned prior art.
[0006] The first aspect of the present application provides a seawater-based zinc-iodine battery electrolyte with high energy density, which includes an additive, seawater, and a zinc salt, and the additive is bromoacetonitrile.
[0007] Preferably, the weight percentage of the additive in the electrolyte is 0.1-30 wt.%. Specifically, the weight percentage of the additive in the electrolyte is 5-16 wt.%.
[0008] Preferably, the zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, zinc perchlorate, zinc tetrafluoroborate, zinc trifluoromethanesulfonate, and zinc bis(trifluoromethylsulfonyl)imide.
[0009] Preferably, the molar concentration of the zinc salt is 1.0-5.0 mol / L -1 Specifically, the molar concentration of the zinc salt is 2.0-4.0 mol / L -1 .
[0010] Preferably, the seawater is natural seawater after coarse filtration and fine filtration.
[0011] The second aspect of the present application further provides a preparation method of the above-mentioned seawater-based zinc-iodine battery electrolyte with high energy density, including the following steps:
[0012] Mix a soluble zinc salt as a solute, filtered seawater as a solvent, and bromoacetonitrile as an additive in proportion, and stir until evenly mixed to obtain the seawater-based zinc-iodine battery electrolyte.
[0013] Specifically, the preparation method of the seawater-based zinc-iodine battery electrolyte with high energy density specifically includes the following steps:
[0014] Under normal atmospheric pressure, dissolve the soluble zinc salt in the filtered seawater, stir and mix evenly, and let it stand to room temperature, then add the bromoacetonitrile additive and mix evenly to obtain the seawater-based zinc-iodine battery electrolyte.
[0015] Preferably, the treatment process of the seawater is as follows: First, perform coarse filtration using a qualitative filter paper or glass fiber filter paper with a pore size range of 5-25 microns; then perform fine filtration using a mixed cellulose ester filter membrane or polyethersulfone filter membrane with a pore size range of 0.1-5 microns; repeat coarse filtration and fine filtration 3- 6 times to obtain the filtered seawater. Specifically, use a qualitative filter paper with a pore size of 11 microns for coarse filtration; use a polyethersulfone filter membrane with a pore size of 0.22 microns for fine filtration; the number of times of coarse filtration and fine filtration are 4 times respectively.
[0016] Preferably, impurities of the bromoacetonitrile additive are removed by 4A molecular sieve after high-temperature activation at 250-450 °C. The high-temperature activation is carried out in a nitrogen or argon atmosphere, and the initial purity of the bromoacetonitrile additive is 97-99.999%. Specifically, the 4A molecular sieve is activated at 450 °C for 3 hours in a nitrogen atmosphere.
[0017] The third aspect of the present application also provides a seawater-based zinc-iodine battery, including 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 high-energy density seawater-based zinc-iodine battery electrolyte.
[0018] Preferably, the separator is made of glass fiber; the current collector used for the iodine-containing positive electrode is selected from one of titanium foil, carbon cloth, carbon paper, and graphite paper. Specifically, the current collector is carbon paper.
[0019] Compared with the prior art, the present application has the following beneficial effects:
[0020] The electrolyte of the present application can generate three pairs of redox peaks during charge and discharge, and can simultaneously stimulate the redox of iodine valence and the redox of bromine valence to achieve six-electron transfer of interhalogen compounds in the zinc-iodine battery, significantly improving the battery capacity. On the one hand, the energy density of the battery of the present application is increased to 3 times the initial value (633 mAh g -1 ), with ultra-high electrochemical performance. On the other hand, the zinc-iodine battery containing the electrolyte of the present application has the advantages of easy manufacturing and low cost, enabling the zinc-iodine battery to better meet commercial needs. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] 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.
[0022] Figure 1 Cyclic voltammogram of the zinc-iodine battery assembled with the electrolyte prepared in Example 1;
[0023] Figure 2 Cycling performance graph of the zinc-iodine battery assembled with the electrolytes prepared in Example 1 and Comparative Example 1;
[0024] Figure 3 Specific capacity-voltage curve of the zinc-iodine battery assembled with the electrolyte prepared in Example 2;
[0025] Figure 4Specific capacity-voltage curve of a zinc-iodine battery assembled with the electrolyte prepared in Comparative Example 1. Detailed implementation manners
[0026] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below with reference to the accompanying drawings in the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts shall fall within the protection scope of the present application.
[0027] Unless otherwise specified, the experimental methods used in the embodiments of the present application are all conventional methods.
[0028] In the following embodiments and comparative examples, unless otherwise specified, all raw materials can be obtained through commercial purchase or prepared by conventional methods.
[0029] Example 1
[0030] The natural seawater was roughly filtered 4 times with qualitative filter paper with a pore size of 11 μm to obtain the preliminarily filtered seawater. The preliminarily filtered seawater was finely filtered 4 times with a polyethersulfone membrane with a pore size of 0.22 μm to obtain the seawater solvent. 109.059 g of zinc trifluoromethanesulfonate was weighed and placed in a glass reagent bottle, 100 ml of the seawater solvent was added, and the mixture was stirred evenly in a magnetic stirring table and allowed to stand until the electrolyte returned to room temperature to obtain the basic electrolyte. The 4 Å molecular sieve was activated at 400 °C in a nitrogen atmosphere to remove impurities, and the 4 Å molecular sieve was immersed in the bromoacetonitrile additive and allowed to stand for 12 to 24 hours. The obtained basic electrolyte was weighed, 8 wt.% of bromoacetonitrile was added, and the mixture was continuously stirred evenly in a magnetic stirring table to obtain the electrolyte containing the additive. The electrolyte was labeled as 3M ZnOTF + 8 wt.% BrAN.
[0031] Example 2
[0032] The natural seawater was roughly filtered 4 times with qualitative filter paper with a pore size of 11 μm to obtain the preliminarily filtered seawater. The preliminarily filtered seawater was finely filtered 4 times with a polyethersulfone membrane with a pore size of 0.22 μm to obtain the seawater solvent. 109.059 g of zinc trifluoromethanesulfonate was weighed and placed in a glass reagent bottle, 100 ml of the seawater solvent was added, and the mixture was stirred evenly in a magnetic stirring table and allowed to stand until the electrolyte returned to room temperature to obtain the basic electrolyte. The 4 Å molecular sieve was activated at 400 °C in a nitrogen atmosphere to remove impurities, and the 4 Å molecular sieve was immersed in the bromoacetonitrile additive and allowed to stand for 12 to 24 hours. The obtained basic electrolyte was weighed, 16 wt.% of bromoacetonitrile was added, and the mixture was continuously stirred evenly in a magnetic stirring table to obtain the electrolyte containing the additive. The electrolyte was labeled as 3M ZnOTF + 16 wt.% BrAN.
[0033] Comparative Example 1
[0034] The natural seawater was roughly filtered 4 times using a qualitative filter paper with a pore size of 11 μm to obtain the preliminarily filtered seawater. The preliminarily filtered seawater was finely filtered 4 times using a polyethersulfone membrane with a pore size of 0.22 μm to obtain the seawater solvent. 109.059 g of zinc trifluoromethanesulfonate was weighed and placed in a glass reagent bottle, 100 ml of the seawater solvent was added, and it was stirred in a magnetic stirring table until evenly mixed, and then left standing until the electrolyte returned to room temperature to obtain an electrolyte without additives. The electrolyte was labeled as 3M ZnOTF.
[0035] Comparative Example 2
[0036] 109.059 g of zinc trifluoromethanesulfonate was weighed and placed in a glass reagent bottle, 100 ml of deionized water solvent was added, and it was stirred in a magnetic stirring table until evenly mixed, and then left standing until the electrolyte returned to room temperature to obtain an electrolyte without additives. The electrolyte was labeled as DI + 3M ZnOTF.
[0037] Comparative Example 3
[0038] 109.059 g of zinc trifluoromethanesulfonate was weighed and placed in a glass reagent bottle, 100 ml of deionized water solvent was added, and it was stirred in a magnetic stirring table until evenly mixed, and then left standing until the electrolyte returned to room temperature to obtain the base electrolyte. The 4 Å molecular sieve was activated at 400 °C in a nitrogen atmosphere to remove impurities, and the 4 Å molecular sieve was immersed in bromoacetonitrile additive and left standing for 12 - 24 hours. The obtained base electrolyte was weighed, 16 wt.% of bromoacetonitrile was added, and it was continuously stirred in a magnetic stirring table until evenly mixed to obtain an electrolyte containing additives. The electrolyte was labeled as DI + 3M ZnOTF.
[0039] Table 1 Ionic Conductivities of Different Electrolytes
[0040]
[0041]
[0042] As can be seen from Table 1, compared with the fast ionic conduction ability of water molecules, the addition of the organic molecule BrAN will reduce the ionic conductivity of a part of the electrolyte. And the supplement of additional strong electrolytes in seawater can weaken the influence of BrAN on the ionic conductivity.
[0043] Battery Assembly and Performance Testing
[0044] The negative electrode used a metal zinc sheet, the separator used glass fiber, the positive electrode used iodine - loaded carbon paper, the battery mold used Swagelok, and the Swagelok - type zinc - iodine battery was assembled using the electrolytes of the above - mentioned examples and comparative examples.
[0045] The battery tests were carried out using a Blue Electric charge-discharge tester, and the cyclic voltammetry tests were carried out using a Gamry electrochemical workstation.
[0046] Figure 1 The cyclic voltammetry curves of the zinc-iodine battery assembled with the electrolyte prepared in Example 1 were tested on a Gamry electrochemical workstation. The data showed that three pairs of redox peaks were formed during the charge-discharge process, corresponding to (1.1 V / 1.25 V), (1.48 V / 1.65 V), and (1.64 V / 1.86 V). The reversibility and feasibility of six-electron transfer were confirmed.
[0047] Figure 2 The long-term cycling performance of the zinc-iodine batteries assembled with the electrolytes prepared in Example 1 and Comparative Example 1 was tested at a current density of 5 A g -1 . Example 1 exhibited an initial specific capacity of 412.4 mAh g -1 , while Comparative Example 1 exhibited an initial specific capacity of 269.5 mAh g -1 . The zinc-iodine battery assembled in Experimental Example 1 had a stable cycle of more than 300 cycles and a capacity retention rate of 70%. However, the zinc-iodine battery assembled in Comparative Example 1 decayed rapidly after 100 cycles and the battery failed at 130 cycles. The above results demonstrated that the zinc-iodine battery assembled in Example 1 had better cycle stability and higher battery energy density.
[0048] Figure 3 The charge-discharge performance of the zinc-iodine battery assembled with the electrolyte prepared in Example 2 was tested. At a current density of 1 A g -1 , three charge-discharge platforms were formed in Example 2, corresponding to three groups of redox in the cyclic voltammetry curve. The charge-discharge curve showed an ultra-high discharge specific capacity of 504.4 mAh g -1 and extremely low voltage polarization.
[0049] Figure 4 The charge-discharge performance of the zinc-iodine battery assembled with the electrolyte prepared in Comparative Example 1 was tested. At a current density of 1 A g -1 , two relatively weak charge-discharge platforms were formed in Comparative Example 1. Due to the presence of chloride ions in seawater, the low-voltage redox corresponded to the high-voltage redox corresponded to . Meanwhile, the charge-discharge curve showed a discharge specific capacity of 199.9 mAh g -1 and a large voltage polarization.
[0050] Combined with Figure 3 and Figure 4 the experimental data, it was proved that the bromoacetonitrile additive had beneficial effects on improving the battery energy density and electrochemical performance.
[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than 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 described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. An electrolyte for a seawater-based zinc-iodine battery with high energy density, characterized in that, The invention comprises an additive, sea water and zinc salt, and the additive is bromoacetonitrile.
2. The seawater-based zinc-iodine battery electrolyte with high energy density according to claim 1, wherein The weight percentage of the additive in the electrolyte is 0.1 to 30 wt.%.
3. The seawater-based zinc-iodine battery electrolyte with high energy density according to claim 1, wherein, The zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, zinc perchlorate, zinc tetrafluoroborate, zinc trifluoromethanesulfonate, and zinc bis(trifluoromethylsulfonyl)imide.
4. The seawater-based 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 5.0 mol / L -1 .
5. The seawater-based zinc-iodine battery electrolyte with high energy density according to claim 1, characterized in that The seawater is natural seawater that has been coarsely filtered and finely filtered.
6. A method for preparing an electrolyte for a seawater-based zinc-iodine battery with high energy density according to any one of claims 1-5, characterized in that, The following steps are involved: The soluble zinc salt is used as a solute, the filtered seawater is used as a solvent, and bromoacetonitrile is used as an additive in proportion and stirred until the mixture is uniform to obtain a seawater-based zinc-iodine battery electrolyte.
7. The preparation method of the seawater-based zinc-iodine battery electrolyte with high energy density according to claim 6, characterized in that, The seawater treatment process is as follows: first, coarse filtration is performed, using qualitative filter paper or glass fiber filter paper with a pore size range of 5 to 25 microns; then, fine filtration is performed, using a mixed cellulose ester filter membrane or polyethersulfone filter membrane with a pore size range of 0.1 to 5 microns; the coarse filtration and fine filtration are repeated 3 to 6 times to obtain filtered seawater.
8. The preparation method of the seawater-based zinc-iodine battery electrolyte with high energy density according to claim 6, characterized in that The bromoacetonitrile additive is removed of impurities by using a 4 angstrom molecular sieve activated at a high temperature of 250-450° C. before use. The high-temperature activation is performed under a nitrogen or argon atmosphere, and the initial purity of the bromoacetonitrile additive is 97-99.999%.
9. A seawater-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 seawater-based zinc-iodine battery electrolyte according to any one of claims 1 to 5.
10. The seawater-based zinc-iodine battery according to claim 9, characterized in that, The diaphragm is made of glass fiber; the current collector used in the iodine-containing positive electrode is selected from one of titanium foil, carbon cloth, carbon paper and graphite paper.