A polyhydroxy electrolyte additive and its application in aqueous zinc ion battery

Abstract

The application relates to the technical field of water-based battery energy storage, and particularly relates to a novel polyhydroxy electrolyte additive and application thereof in a water-based zinc ion battery. The polyhydroxy electrolyte additive is a water-soluble organic compound, which is D-mannitol pentahydrate. In the application, the electrolyte additive regulates the interaction between zinc ion water molecules and sulfate radicals through the directional reconfiguration effect of hydrogen bonds due to the polyhydroxy structure, further regulates the solvation structure of hydrated zinc ions, repels water molecules and sulfate anions at the electrode-electrolyte interface, and avoids the interface corrosion and hydrogen evolution side reactions caused by water and sulfate. In addition, the D-mannitol pentahydrate can stabilize the metal-electrolyte interface through chemical adsorption, guide uniform planar zinc deposition, inhibit the formation and growth of zinc dendrites, and prolong the service life of the battery.

Description

TECHNICAL FIELD

[0001] The application relates to a novel multi-hydroxyl electrolyte additive and application thereof in a water-based zinc ion battery, and belongs to the technical field of water-based energy storage batteries. BACKGROUND

[0002] In recent years, lithium ion batteries have dominated the electronic industry and energy storage market due to their high energy density. However, the shortage of lithium resources and safety problems have raised doubts about their use and development. Therefore, it is urgent to develop low-cost and safe and reliable energy storage technologies. Water-based zinc ion batteries have the advantages of safety, environmental protection, rich zinc reserves, and the like, and the theoretical capacity of zinc metal is high (820 mAh g -1 / 5855 mAh cm -2 ), and the redox potential is low (-0.76 V vs SHE), so the water-based zinc ion battery is considered as a favorable competitor in the field of large-scale energy storage and is expected to be widely used. However, in the neutral / weak acid electrolyte, zinc metal is prone to cause hydrogen evolution, corrosion passivation and other parasitic side reactions due to its inherent thermodynamic instability, promotes uneven zinc deposition, induces disorderly dendrite growth problems, and thus causes instability of the electrode / electrolyte interface, capacity reduction of the battery, low coulombic efficiency and short cycle life. Therefore, it is of great significance to inhibit dendrite growth and limit the occurrence of side reactions for the further development of zinc ion batteries.

[0003] In order to solve the above problems, researchers have proposed various improvement strategies, such as constructing an artificial interface protection layer, designing a zinc negative electrode structure, and introducing an electrolyte additive. The construction of an artificial interface protection layer and the design of a zinc negative electrode structure often require complicated synthesis steps, and the synthesis process also involves many unstable factors. Therefore, adding a functional additive to the water-based electrolyte is considered as a simple and practical solution. However, the existing electrolyte additives still have some deficiencies, such as the organic polymer additive which increases the ion transmission resistance, or other additives which have a single function of inhibiting side reactions or dendrite growth. Therefore, it is still necessary to further find a new excellent additive which can improve the ion transmission kinetics and simultaneously inhibit side reactions and dendrite growth, so as to further improve the electrochemical performance of the water-based zinc ion battery. SUMMARY

[0004] The application relates to a novel multi-hydroxyl electrolyte additive and application thereof in a water-based zinc ion battery.

[0005] The present application aims to provide a new polyhydroxy electrolyte additive with the scientific name of D-mannitol pentahydrate, which regulates the interaction between zinc ions, water molecules and sulfate radicals through the directional reconfiguration effect of hydrogen bonds, further regulates the solvation structure of hydrated zinc ions, repels water molecules and sulfate anions at the electrode-electrolyte interface, avoids the interface corrosion and hydrogen evolution side reactions involving water and sulfate, and the additive can stabilize the metal-electrolyte interface through chemical adsorption, guide uniform planar zinc deposition, thereby inhibiting the formation and growth of zinc dendrites and prolonging the service life of the battery.

[0006] The technical solution of the present application is as follows: a new polyhydroxy electrolyte additive is D-mannitol pentahydrate.

[0007] A water-based zinc ion battery electrolyte containing the above-mentioned new polyhydroxy electrolyte additive, the electrolyte uses a soluble zinc salt as an electrolyte salt, D-mannitol pentahydrate as an additive, and high-purity deionized water as a solvent.

[0008] The water-based zinc ion battery electrolyte described above, the concentration of D-mannitol pentahydrate is 0.1 mol / L -1 .

[0009] The water-based zinc ion battery electrolyte described above, the soluble zinc salt is one or more of zinc sulfate, zinc chloride, zinc acetate, and zinc trifluoromethane sulfonate.

[0010] The water-based zinc ion battery electrolyte described above, the concentration of the soluble zinc salt is 2 mol / L -1 .

[0011] A water-based zinc ion battery includes a positive electrode, a negative electrode, a separator, and the above-mentioned water-based zinc ion battery electrolyte.

[0012] The water-based zinc ion battery described above is a symmetric battery composed of zinc foil, glass fiber separator and electrolyte; or a full battery composed of zinc foil as negative electrode, vanadium oxide as positive electrode and electrolyte.

[0013] The water-based zinc ion battery described above, the vanadium oxide is one or a combination of two or more of ammonium vanadate, vanadium dioxide or vanadium pentoxide.

[0014] A water-based zinc ion full battery includes a positive electrode, a negative electrode, a separator, and the above-mentioned electrolyte.

[0015] The above water-based zinc ion full battery, the positive electrode is prepared by mixing vanadium pentoxide, Super P and polyvinylidene fluoride in a mass ratio of 7:2:1, uniformly grinding, using N-methyl pyrrolidone as a solvent to prepare a positive electrode slurry, and coating the slurry on a titanium foil by using a doctor blade and vacuum drying to obtain a positive electrode with a loading of 1-2 mg cm -2 .

[0016] The beneficial effects that can be produced by the present application include:

[0017] 1、The electrolyte additive provided by the present application has a multi-hydroxyl structure, which regulates the interaction between zinc ions, water molecules and sulfate radicals through the directional restructuring effect of hydrogen bonds, further regulates the solvation structure of hydrated zinc ions, repels water molecules and sulfate anions at the electrode-electrolyte interface, avoids the interface corrosion and hydrogen evolution side reactions caused by water and sulfate, and thus improves the electrochemical performance of the zinc ion battery.

[0018] 2、The electrolyte additive provided by the present application can stabilize the metal-electrolyte interface through chemical adsorption, guide uniform planar zinc deposition, thereby inhibiting the formation and growth of zinc dendrites, and prolonging the service life of the battery.

[0019] 3、The electrolyte additive provided by the present application has inherent advantages such as low price, safety, environmental protection, simple preparation method, wide application range, etc. It has great application prospect and research value in the field of new energy batteries. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a comparison chart of the charge-discharge curves of the Zn||Zn symmetric battery of the different electrolyte systems of the present application example 3;

[0021] Figure 2 It is a comparison chart of the rate performance of the Zn||Zn symmetric battery of the different electrolyte systems of the present application example 4;

[0022] Figure 3 It is a comparison chart of the SEM of the zinc negative electrode surface after 20 cycles of the Zn||Zn symmetric battery of the different electrolyte systems of the present application example 5;

[0023] Figure 4 It is a comparison chart of the constant current charge-discharge curves of the Zn||V2O5 full battery of the different electrolyte systems of the present application example 6 at 0.5 Ag -1 current density;

[0024] Figure 5 It is a comparison chart of the constant current charge-discharge curves of the Zn||V2O5 full battery of the different electrolyte systems of the present application example 6 at 3 Ag -1 current density. DETAILED DESCRIPTION

[0025] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. The specific examples described in the present application are only used to explain the present application and are not used to limit the present application.

[0026] Unless otherwise defined, the professional terms used below are consistent with the meanings understood by those skilled in the art; unless otherwise specified, the raw materials and reagents in the examples of the present application are purchased through commercial channels or prepared by known methods.

[0027] The analysis method in the examples of the present application is as follows:

[0028] The constant current charge and discharge test is carried out at different current densities by using a blue cell test instrument, and the cycle life and coulombic efficiency under different test conditions are analyzed.

[0029] The present application provides a novel multi-hydroxyl electrolyte additive applied to an aqueous zinc ion battery electrolyte, which is prepared by the following method steps:

[0030] At room temperature, 5.75 g of zinc sulfate is added to 10 mL of deionized water, ultrasonic stirring is carried out until the solution is clear, and 2 mol / L of zinc sulfate solution (referred to as ZS) is obtained. -1

[0031] In the above zinc sulfate electrolyte, 0.59 g of D-levan is added to obtain an electrolyte with a D-levan concentration of 0.1 mol / L (referred to as ZS-RP). -1

[0032] The button cell used in this example is CR2032.

[0033] High-purity zinc foil with a thickness of 100 pm (purity of 99.99%) is cut into a circular piece with a diameter of 12 mm for standby; the glass fiber separator is cut into a circular piece with a diameter of 16 mm for standby; the titanium foil is cut into a circular piece with a diameter of 12 mm for standby.

[0034] Experimental Example 1: Aqueous zinc ion symmetrical button cell (Zn||Zn symmetrical cell)

[0035] Assembly: The zinc foil is used as the positive and negative electrode sheets of the button cell. First, the positive electrode sheet is placed in the positive electrode shell, then the glass fiber separator is placed, and then 100 pL of the above ZS, ZS-RP electrolyte is dropped, respectively, and then the negative electrode sheet is placed, and then the gasket and spring are placed in turn, and finally the negative electrode shell is buckled, and the battery is packaged by using a battery packaging machine, thereby obtaining two Zn||Zn symmetrical cells with zinc sulfate as the electrolyte and the zinc sulfate mixed solution containing D-levan additive as the electrolyte. ​​

[0036] Experimental Example 2 Aqueous zinc-ion full cell (Zn||V2O5 cell)

[0037] An aqueous zinc-ion full cell, the positive active material of which is vanadium pentoxide, was assembled by the following steps:

[0038] (1) Electrolyte: ZS and ZS-RP electrolytes were used as the electrolyte of the aqueous zinc-ion full cell, respectively.

[0039] (2) Preparation of the positive electrode sheet: Vanadium pentoxide, Super P and polyvinylidene fluoride were mixed in a mass ratio of 7:2:1, ground uniformly in a mortar, and made into a positive electrode slurry with N-methylpyrrolidone as the solvent. The slurry was coated onto a titanium foil using a doctor blade and dried in a vacuum at 60°C for 12 hours to obtain a positive electrode sheet with a loading of 1-2 mg cm -2 .

[0040] (3) Assembly of the aqueous zinc-ion full cell: The aqueous zinc-ion full cell was assembled from the positive electrode sheet prepared in step (2), ZS and ZS-RP electrolytes, a glass fiber separator and a zinc foil negative electrode. The cells were assembled in the order of positive electrode, separator and negative electrode to obtain two Zn||V2O5 cells with zinc sulfate as the electrolyte and a mixed solution of zinc sulfate containing D-muscadine sugar additive as the electrolyte. Example 3

[0041] The Zn||Zn symmetric cell of Example 1 was subjected to constant current charge-discharge cycle tests at 1 mA cm -2 / 1 mAh cm -2 , and the cycle times of the respective cells are shown in Figure 1 . The Zn||Zn symmetric cell without D-muscadine sugar additive short-circuited after less than 100 hours of cycling, while the Zn||Zn symmetric cell with D-muscadine sugar additive had a cycle time of up to 1500 hours, and the cycle life of the cell was significantly prolonged. Example 4

[0042] The Zn||Zn symmetric cell obtained in Example 1 was subjected to rate cycling tests at 0.5-20 mA cm -2 , and the cycle times of the respective cells are shown in Figure 2 . The Zn||Zn symmetric cell containing only zinc sulfate short-circuited at less than 5 mA cm -2 , while the Zn||Zn symmetric cell with D-muscadine sugar additive was able to cycle completely to a current density of 20 mA cm -2 , and had good rate cycling performance. Example 5

[0043] The Zn||Zn symmetric battery obtained in Example 1 was subjected to constant current charge-discharge cycling at 1 mA cm -2 / 1 mAh cm -2 for 20 cycles under the condition, Figure 3 The SEM image of the surface of the zinc negative electrode after cycling. It can be seen that the zinc negative electrode of the Zn||Zn symmetric battery added with D-Phosphosaccharide has a smooth surface, indicating that the electrolyte containing D-Phosphosaccharide additive can induce uniform zinc ion deposition and inhibit corrosion and hydrogen evolution side reactions. However, the zinc negative electrode surface of the Zn||Zn symmetric battery without addition shows a large number of anisotropic square flake dendrites, which will further cause short circuit of the battery. Example 6

[0044] The Zn||V2O5 battery of Example 2 was subjected to constant current charge-discharge test at current density of 0.5 A g -1 and 3 A g -1 , respectively, and the results are shown in Figure 4 , Figure 5 The results show that during the cycling process at two current densities, the Zn||V2O5 battery containing D-Phosphosaccharide additive is always more stable than that without addition, and the Zn||V2O5 battery containing D-Phosphosaccharide has higher capacity retention rate.

[0045] From the above embodiments and test data, it can be seen that the method described in the present application is simple, low cost and effective, and has important significance for inhibiting dendrite growth and side reactions in aqueous zinc ion battery and promoting long-life application of aqueous zinc ion battery in the future.

[0046] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments and belong to the scope of the technical solution.

Claims

1. An aqueous zinc-ion battery electrolyte comprising a polyhydroxy electrolyte additive, characterized in that, The electrolyte is composed of electrolyte salt, additive and solvent, takes soluble zinc salt as electrolyte salt, takes D-mannitol pentahydrate as additive, and takes high-purity deionized water as solvent, and the soluble zinc salt is zinc sulfate.

2. The aqueous zinc-ion battery electrolyte of claim 1, wherein, D-mannose pentahydrate was at a concentration of 0.1 mol L -1 .

3. The aqueous zinc-ion battery electrolyte of claim 1, wherein, The concentration of the soluble zinc salt is 2 mol L -1 .

4. An aqueous zinc-ion battery, characterized in that, The water-based zinc ion battery electrolyte comprises a positive electrode, a negative electrode, a separator and the electrolyte of any one of claims 1-3.

5. The aqueous zinc-ion battery of claim 4, wherein, The water-based zinc ion battery is a symmetric battery composed of a zinc foil, a glass fiber separator and an electrolyte, or is a full battery composed of a zinc foil as a negative electrode, a vanadium oxide as a positive electrode and an electrolyte.

6. The aqueous zinc-ion battery of claim 5, wherein, The vanadium oxide is one or a combination of two or more of ammonium vanadate, vanadium dioxide or vanadium pentoxide.

7. An aqueous zinc-ion all-solid-state battery, characterized by comprising: The water-based zinc ion battery electrolyte comprises a positive electrode, a negative electrode, a separator and the electrolyte of any one of claims 1-3.

8. The aqueous zinc-ion full cell of claim 7, wherein, The positive electrode is prepared by mixing vanadium pentoxide, Super P and polyvinylidene fluoride in a mass ratio of 7:2:1, grinding uniformly, using N-methyl pyrrolidone as a solvent to prepare a positive electrode slurry, coating the slurry on a titanium foil by using a doctor blade, and vacuum drying to obtain a positive electrode sheet with a loading of 1-2 mg cm -2 .

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