Aqueous magnesium ion battery electrolyte and application thereof
By adding sulfone compounds to the electrolyte of aqueous magnesium-ion batteries, the hydrogen bonds between PEG molecules are broken, the viscosity is reduced, and the activity of water molecules is inhibited. This solves the problems of high viscosity and low ionic conductivity of PEG-based electrolytes and improves the performance of the batteries.
Patent Information
- Application Number
- CN202511079932.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-01
- Publication Date
- 2025-11-04
AI Technical Summary
Existing PEG-based aqueous magnesium-ion battery electrolytes have high viscosity and low ionic conductivity, which limits the improvement of battery performance.
Sulfone compounds are used as additives to disrupt the hydrogen bond network between PEG molecules, reduce electrolyte viscosity and increase ionic conductivity, while inhibiting the activity of water molecules and reducing hydrogen evolution side reactions.
It significantly reduces electrolyte viscosity, improves ion migration efficiency, reduces side reactions, and enhances battery discharge specific capacity and cycle stability.
Smart Images
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of aqueous magnesium ion batteries, and particularly relates to a polyethylene glycol-based aqueous magnesium ion battery electrolyte containing a sulfone compound additive and application thereof. BACKGROUND
[0002] Under the background of accelerating global energy transformation, the energy storage industry is showing explosive growth. Lithium ion batteries have become the current mainstream technology due to their high energy density and other advantages. However, their application in large-scale energy storage is facing severe challenges due to cost pressure caused by the scarcity of lithium resources and safety hazards caused by flammable organic electrolytes.
[0003] Aqueous magnesium ion batteries have gradually become a research hotspot in the energy storage field due to their advantages such as abundant magnesium resources, low cost, and intrinsic safety. As a key component of the battery system, the properties of the electrolyte directly affect ion transmission efficiency, interface stability, and cycle life. Polyethylene glycol (PEG) as an additive can improve the performance of aqueous electrolytes, but the high viscosity and low ionic conductivity of PEG-based electrolytes seriously restrict the further improvement of battery performance. Therefore, there is an urgent need to develop aqueous magnesium ion battery electrolytes with low viscosity and high ionic conductivity. SUMMARY
[0004] The application aims to provide an aqueous magnesium ion battery electrolyte with high ionic conductivity and low viscosity to solve the technical defects of high viscosity and low ionic conductivity of existing PEG-based electrolyte systems.
[0005] To achieve the above-mentioned purpose, the application adopts the following technical solution: an aqueous magnesium ion battery electrolyte, comprising a magnesium salt, water, polyethylene glycol 400 (PEG400), and an additive, characterized in that the additive is a sulfone compound.
[0006] The innovation mechanism of the application lies in that the strong polarity of the sulfone group (-SO2-) in the sulfone compound can destroy the hydrogen bond network between PEG molecules, significantly reducing the viscosity of the electrolyte system and improving the ionic conductivity. At the same time, the sulfone compound and PEG400 synergistically act to effectively inhibit the activity of water molecules, thereby reducing the hydrogen evolution side reaction.
[0007] Further, in the electrolyte, the sulfone compound is selected from at least one of tetramethylene sulfone, cyclohexyl sulfone, cyclopentyl sulfone, and dimethyl sulfoxide.
[0008] The volume fraction of the additive in the electrolyte is 0.01% to 50%, preferably 25% to 50%, water is not limited, and the volume fraction of water is further preferably 20%; the balance is polyethylene glycol 400.
[0009] The magnesium salt is selected from at least one of magnesium chloride, magnesium fluoride, magnesium bromide, magnesium iodide, magnesium nitrate, magnesium sulfate, magnesium acetate, magnesium perchlorate and magnesium bistrifluoromethylsulfonylimide. The concentration of the magnesium salt is 0.01-2 mol / L -1 .
[0010] Preparation method: polyethylene glycol 400, sulfone additive and water are mixed according to the volume ratio, and the magnesium salt is added and stirred to dissolve; the stirring speed is 600-1800 r / min-1, and the stirring time is at least 8 hours.
[0011] The second aspect of the application provides the application of the above-mentioned electrolyte in a magnesium ion battery.
[0012] A magnesium ion battery comprises a positive electrode, a negative electrode and the above-mentioned aqueous magnesium ion battery electrolyte; further, the positive electrode material comprises vanadium pentoxide or manganese oxide; and the negative electrode material comprises 3,4,9,10-perylenetetracarboxylic diimide or vanadium oxide.
[0013] The application has the following beneficial effects by adding sulfone compound additives:
[0014] Reducing viscosity and improving electrical conductivity: the sulfone group destroys the hydrogen bond between PEG molecules, which significantly reduces the viscosity of the electrolyte and improves the ion migration efficiency. For example, the viscosity of the electrolyte containing the sulfolane additive is reduced to 47.10 mPa s, and the ion conductivity reaches 1767 μS cm -1 , while the viscosity of the control group without additives is as high as 223.4 mPa s, and the conductivity is only 480 μS cm -1 .
[0015] Inhibiting hydrogen evolution reaction: sulfone compounds and PEG cooperatively limit water activity and reduce side reactions.
[0016] Improving battery performance: full battery test shows that the discharge specific capacity of the system containing the additive is 142.4 mAh g -1 , and the specific capacity of the control group is only 49.5 mAh g -1 .
[0017] In summary, the sulfone additive significantly improves the rate performance, cycle stability and energy output power of the aqueous magnesium ion battery by optimizing the physical and chemical properties of the electrolyte.
[0018] The application will be further described below in combination with the drawings and specific implementation methods. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 Product picture of the electrolyte prepared for implementation 1.
[0020] Figure 2The full cell cycle performance test chart prepared for Example 1.
[0021] Figure 3 The full cell rate performance test chart prepared for Example 1.
[0022] Figure 4 The full cell cycle performance test chart prepared for Example 2.
[0023] Figure 5 The full cell cycle performance test chart prepared for Example 3.
[0024] Figure 6 The full cell cycle performance test chart prepared for Comparative Example 1.
[0025] Figure 7 The viscosity and ionic conductivity curves of the electrolyte prepared for Examples 1, 2, 3, and Comparative Example 1. DETAILED DESCRIPTION
[0026] In order to make the objects, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the present application will be described below in connection with specific embodiments. It should be noted that the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.
[0027] Example 1
[0028] (1) 2 mL of polyethylene glycol, 2 mL of sulfolane, and 1 mL of water were mixed, and 1.46 g of bis(trifluoromethylsulfonyl)imide magnesium was added. The mixture was stirred at room temperature for 12 hours to prepare an electrolyte, which was named as polyethylene glycol / sulfolane / bis(trifluoromethylsulfonyl)imide magnesium electrolyte. The product form of the obtained electrolyte is shown in Figure 1 .
[0029] (2) The viscosity and ionic conductivity of the above electrolyte were tested, and a water-based magnesium ion full cell was assembled using the electrolyte (further described positive electrode material includes vanadium pentoxide; the negative electrode material includes 3,4,9,10-perylenetetracarboxylic diimide or vanadium oxide), and the cycle performance was tested. As shown in Figure 2 , the maximum discharge capacity of the full cell was 142.2 mAh g -1 at a current density of 100 mAg -1 . Figure 3 The rate cycle performance of the battery in the range of 100-1000 mAg -1 current density is shown.
[0030] Example 2
[0031] (1) Mix 2 mL of polyethylene glycol, 2 mL of dimethyl sulfoxide and 1 mL of water, and add 0.59 g of magnesium nitrate. Stir the mixture at room temperature for 12 hours to obtain an electrolyte, which is named polyethylene glycol / dimethyl sulfoxide / magnesium nitrate electrolyte.
[0032] (2) Assemble an aqueous magnesium-ion full cell using the above electrolyte and test its cycle performance. For example... Figure 4 As shown, at 100mAg -1 At the specified current density, the maximum discharge specific capacity of the full cell is 117.3 mAh g. -1 .
[0033] Example 3
[0034] (1) Mix 2 mL of polyethylene glycol, 2 mL of cyclopentyl sulfone and 1 mL of water, add 0.38 g of magnesium chloride, stir the mixture at room temperature for 12 hours to obtain an electrolyte, named polyethylene glycol / cyclopentyl sulfone / magnesium chloride electrolyte.
[0035] (2) Assemble an aqueous magnesium-ion full cell using the above electrolyte and test its cycle performance. For example... Figure 5 As shown, at 100mAg -1 At the specified current density, the maximum discharge specific capacity of the full cell is 103.9 mAh g. -1 .
[0036] Comparative Example 1
[0037] (1) Mix 4 mL of polyethylene glycol with 1 mL of water, add 1.46 g of magnesium bis(trifluoromethanesulfonyl)imide, stir the mixture at room temperature for 12 hours to obtain an electrolyte, named polyethylene glycol / magnesium bis(trifluoromethanesulfonyl)imide electrolyte.
[0038] (2) Assemble an aqueous magnesium-ion full cell using the above electrolyte and test its cycle performance. For example... Figure 6 As shown, at 100mAg -1 At the given current density, the discharge specific capacity of the full cell is 49.5 mAh g. -1 .
[0039] Performance comparison:
[0040] The ionic conductivity and viscosity of the polyethylene glycol / sulfolane / bis(trifluoromethanesulfonyl)imide magnesium electrolyte, polyethylene glycol / dimethyl sulfoxide / magnesium nitrate electrolyte, polyethylene glycol / cyclopentyl sulfone / magnesium chloride electrolyte prepared in Examples 1-3, and the polyethylene glycol / bis(trifluoromethanesulfonyl)imide magnesium electrolyte prepared in Comparative Example 1 were tested respectively. The results are as follows: Figure 7 As shown.
[0041] The sulfone compound water-based magnesium ion battery electrolyte (Examples 1-3) provided by the present application exhibits lower viscosity, higher ionic conductivity (as shown in Table 1) and significantly improves the discharge specific capacity of the full battery (as shown in Table 2) compared to the electrolyte without adding such a solvent (Comparative Example 1). Figure 7 Figure 2 Figure 4 Figure 5 Figure 6 Based on this, the present application provides a high-performance electrolyte with low viscosity, high ionic conductivity, and can give water-based magnesium ion batteries excellent cycle performance and high coulomb efficiency.
Claims
1. An aqueous magnesium-ion battery electrolyte, comprising magnesium salt, water, polyethylene glycol 400 (PEG400), and additives, characterized in that: The additive is a sulfone compound.
2. The aqueous magnesium-ion battery electrolyte according to claim 1, characterized in that, The sulfone compound is selected from at least one of sulfolane, cyclohexyl sulfone, cyclopentyl sulfone, and dimethyl sulfoxide.
3. The aqueous magnesium-ion battery electrolyte according to claim 1, characterized in that, The magnesium salt is selected from at least one of magnesium chloride, magnesium fluoride, magnesium bromide, magnesium iodide, magnesium nitrate, magnesium sulfate, magnesium acetate, magnesium perchlorate, and magnesium bis(trifluoromethanesulfonyl)imide.
4. The aqueous magnesium-ion battery electrolyte according to claim 1, characterized in that, The volume fraction of the additive in the electrolyte is 0.01% to 50%, preferably 25% to 50%.
5. The aqueous magnesium-ion battery electrolyte according to claim 1, characterized in that, The concentration of the magnesium salt is 0.01–2 mol / L. -1 .
6. A method for preparing an aqueous magnesium-ion battery electrolyte according to any one of claims 1-5, characterized in that, Polyethylene glycol 400, sulfone additives and water were mixed in a volume ratio, and magnesium salt was added and stirred until dissolved.
7. The method according to claim 6, characterized in that, The stirring speed is 600–1800 rpm. -1 The stirring time should be at least 8 hours.
8. A magnesium-ion battery, characterized in that: It includes a positive electrode, a negative electrode, and the aqueous magnesium-ion battery electrolyte as described in any one of claims 1-5.
9. The magnesium-ion battery according to claim 8, characterized in that: The cathode material includes vanadium pentoxide or manganese oxide.
10. The magnesium-ion battery according to claim 8, characterized in that: The anode materials include 3,4,9,10-perylenetetracarboxydiimide or vanadium oxide.