Alkyl glycoside aqueous electrolyte for zinc ion battery and preparation method and application thereof

Abstract

The application belongs to the technical field of aqueous batteries, and particularly relates to an alkyl glycoside aqueous zinc ion battery electrolyte, a preparation method and application thereof. The electrolyte comprises a solvent water, an electrolyte and an additive; and the additive is an alkyl glycoside. The alkyl glycoside additive with double adsorption functions for zinc ions and a zinc metal (002) crystal surface is added in the electrolyte. The additive not only can break the close combination of a water sheath layer [Zn(H2O)6] 2+ ] in a traditional aqueous electrolyte and zinc ions, prevent water molecules from contacting the zinc metal, and thus relieve the hydrogen evolution corrosion reaction of the zinc metal, but also can have a higher adsorption energy for the zinc metal (002) crystal surface than for a (100) crystal surface, so as to guide the zinc ions to be more reduced and deposited on the (002) crystal surface, and the zinc atoms mainly grow horizontally on the zinc metal (002) crystal surface, and thus the generation of zinc dendrites is avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aqueous batteries, and particularly relates to an alkyl glycoside aqueous zinc ion battery electrolyte, a preparation method and application thereof. BACKGROUND

[0002] Zinc metal has a high theoretical capacity (5855 mAh cm -2 and 820 mAh g -1 ), a low redox potential (-0.76 V compared with the standard hydrogen electrode), a high reserve, water compatibility and safety, and is selected as an ideal negative electrode material of an aqueous battery. An electrolyte is an important component of a zinc ion battery and has an important influence on the electrochemical reversibility of a zinc metal negative electrode. First, the uneven distribution of a local electric field at the electrolyte / electrode interface inevitably leads to the disordered deposition of zinc and the formation of zinc dendrites, thereby shortening the service life of the battery and causing other problems. In addition, zinc ions in a traditional aqueous electrolyte exist in the form of [Zn(H2O)6] 2+ The water molecules in the solvation structure of zinc ions have chemical activity and are easy to cause hydrogen evolution on the surface of zinc metal in an electrochemical reaction, causing the pH value near the electrode interface to rise, corroding the zinc metal electrode, and thereby generating an insulating byproduct.

[0003] At present, significant progress has been made in solving the problems of dendrite growth and interface instability commonly found in rechargeable battery metal negative electrodes. However, the above strategies cannot effectively solve the unique solvent water side reaction problem in zinc ion batteries. In view of this problem, various additives, such as high-concentration electrolyte salts, organic compounds, inorganic salts, etc., are introduced into the electrolyte. However, most of the additives have the problems of high price, high danger and environmental pollution, which are contrary to the advantages of low cost and high safety of zinc ion batteries. Therefore, it is of great significance to find a low-cost, non-toxic, abundant additive to optimize the electrolyte of a zinc ion battery. SUMMARY

[0004] The present application aims at the problems that zinc metal negative electrode is easy to grow zinc dendrites and cause hydrogen evolution corrosion reaction in zinc ion battery aqueous electrolyte, eventually leading to battery short circuit and shortening of cycle life, and provides a glycoside aqueous zinc ion battery electrolyte additive. In the zinc ion battery aqueous electrolyte, alkyl glycoside not only can break the solvent sheath of hydrated zinc ions combined with zinc ions, but also can have stronger adsorption with the (002) crystal face horizontally deposited in zinc metal. Therefore, under the dual action of alkyl glycoside additive, zinc ions are more likely to be reduced and deposited on the (002) crystal face, avoiding the generation of zinc dendrites, and the water molecules causing hydrogen evolution corrosion reaction are difficult to reach the surface of zinc metal, so as to realize the reduction of by-products and corrosion reaction on the surface of zinc metal. Therefore, the electrolyte modified by alkyl glycoside additive can significantly improve the cycle performance and corrosion resistance of zinc ion battery. Meanwhile, the present application also realizes the high-value utilization of biomass-based alkyl glycoside.

[0005] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0006] In one aspect, the present application provides an alkyl glycoside aqueous zinc ion battery electrolyte, which comprises solvent water, electrolyte and additive; the additive is alkyl glycoside, and its general structure is as follows:

[0007]

[0008] Wherein, n is the degree of polymerization, and R is an alkyl group.

[0009] In the above technical scheme, further, in the alkyl glycoside, the degree of polymerization n is 1-3.

[0010] In the above technical scheme, further, in the alkyl glycoside, R is an alkyl group of C8-C16.

[0011] In the above technical scheme, further, in the electrolyte, the mass fraction of the additive is 0.01-30%.

[0012] In the above technical scheme, further, the electrolyte is any one or a combination of two or more of zinc sulfate, zinc chloride and zinc trifluoromethane sulfonate.

[0013] In the above technical scheme, further, in the electrolyte, the molar concentration of the electrolyte is 1-3 mol / L.

[0014] In another aspect, the present application provides a preparation method of the above-mentioned alkyl glycoside aqueous zinc ion battery electrolyte, which comprises the following steps:

[0015] (1) Dissolve the electrolyte in solvent water to obtain an aqueous zinc ion battery electrolyte;

[0016] (2) adding the alkyl glycoside additive into the aqueous zinc ion battery electrolyte obtained in step (1) to obtain the alkyl glycoside aqueous zinc ion battery electrolyte.

[0017] In still another aspect of the present application, the above alkyl glycoside aqueous zinc ion battery electrolyte is applied in an aqueous zinc ion battery or a zinc ion electrochemical energy storage device.

[0018] The present application has the following beneficial effects:

[0019] The alkyl glycoside additive added in the electrolyte of the present application has a dual adsorption function with zinc ions and zinc metal (002) crystal surface. The additive not only breaks the close combination of the water sheath layer [Zn(H2O)6] 2+ and zinc ions in the traditional aqueous electrolyte, prevents water molecules from contacting zinc metal, and thus alleviates the hydrogen evolution corrosion reaction of zinc metal, but also has a higher adsorption energy with zinc metal (002) crystal surface than (100) crystal surface, thereby guiding zinc ions to be more reduced and deposited on the (002) crystal surface, and zinc atoms mainly grow horizontally on the zinc metal (002) crystal surface, thus avoiding the generation of zinc dendrites.

[0020] The alkyl glycoside additive added in the electrolyte of the present application has a dual effect of inhibiting hydrogen evolution corrosion and dendrite growth, which is of great significance in avoiding battery short circuit and improving battery cycle life. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The SEM morphology and XRD pattern of the blank zinc electrode, wherein a is the SEM morphology, and b is the XRD pattern;

[0022] Figure 2 The SEM morphology and XRD pattern of the zinc electrode of Comparative Example 1 after 10 days in the electrolyte, wherein a is the SEM photo with a magnification of 1000 times, b is the SEM photo with a magnification of 30000 times, and c is the XRD pattern;

[0023] Figure 3 The SEM morphology and XRD pattern of the zinc electrode of Example 1 after 10 days in the electrolyte, wherein a is the SEM photo with a magnification of 1000 times, b is the SEM photo with a magnification of 30000 times, and c is the XRD pattern;

[0024] Figure 4 The SEM morphology of the zinc electrode of Comparative Example 1 after deposition in the electrolyte, wherein a is a magnification of 1000 times, and b is a magnification of 30000 times;

[0025] Figure 5 The SEM morphology of the zinc electrode of Example 1 after deposition in the electrolyte, wherein a is a magnification of 1000 times, and b is a magnification of 30000 times;

[0026] Figure 6 The corrosion resistance curve of the zinc electrode in the electrolyte is shown in Comparative Example 1.

[0027] Figure 7 The corrosion resistance curve of the zinc electrode in the electrolyte in Example 1 is shown.

[0028] Figure 8 The cycling curve of the zinc electrode in the electrolyte is shown in Comparative Example 1.

[0029] Figure 9 The cycling curve of the zinc electrode in the electrolyte in Example 1 is shown. Detailed Implementation

[0030] The following examples are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0031] Example 1

[0032] Dissolve 0.045 g of alkyl glycoside additive (APG) (50% aqueous solution) in 15 g of 2 mol / L ZnSO4 electrolyte to prepare an electrolyte with an APG to ZnSO4 mass ratio of 0.15%.

[0033] 1. Immersion test of zinc sheets in electrolyte containing APG additive

[0034] The zinc metal electrode was immersed in an electrolyte containing APG additive for 10 days. The SEM morphology and XRD patterns after immersion were as follows: Figure 3 a, b, and c. The zinc electrode surface is smooth with no obvious corrosion, and the XRD pattern shows no byproduct formation.

[0035] 2. Zinc deposition morphology

[0036] Copper foil was used as a current collector and placed in an electrolyte containing APG additive for zinc deposition. The deposition morphology is as follows: Figure 5 a, b.

[0037] 3. Corrosion resistance curve test

[0038] The corrosion resistance curve LSV was tested using a three-electrode system in an electrolyte containing APG additive, as shown in Figure 7.

[0039] 4. Cycle life test of zinc symmetric battery

[0040] Zinc symmetric cells were prepared using an electrolyte containing APG additive, and their cycle life was tested. Figure 9 As shown, the cycle life can reach 4000h.

[0041] Comparative Example 1

[0042] Prepare an additive-free 2 mol / L ZnSO4 electrolyte.

[0043] 1. Immersion experiment of zinc sheet in ZnSO4 electrolyte

[0044] The zinc metal electrode was immersed in ZnSO4 electrolyte for 10 days. The SEM morphology and XRD patterns after immersion are shown in Figures 2a, b, and c. Obvious corrosion was observed on the surface of the zinc electrode, and the XRD patterns showed the formation of byproducts.

[0045] 2. Zinc deposition morphology

[0046] Zinc deposition was performed by placing copper foil as a current collector in a ZnSO4 electrolyte, and the deposition morphology was as follows: Figure 4 a, b.

[0047] 3. Corrosion resistance curve test

[0048] The corrosion resistance curve LSV was tested using a three-electrode system in a ZnSO4 electrolyte, such as... Figure 6 Compared to the electrolyte in Example 1, the corrosion potential in Comparative Example 1 shifted significantly to the left.

[0049] 4. Cycle life test of zinc symmetric battery

[0050] A zinc symmetric battery was prepared using ZnSO4 electrolyte, and its cycle life was tested; it could only cycle for 140 hours. Figure 8 The cycle life is much shorter than that of the electrolyte in Example 1.

[0051] Results analysis:

[0052] Comparative Example 1: SEM image of the zinc electrode after immersion in ZnSO4 electrolyte for 10 days ( Figure 2 (a) and (b) show that a large number of byproducts were generated on the electrode surface, as indicated by the XRD patterns. Figure 2 c) Analysis revealed it to be Zn4SO4(OH)6·5H2O, a byproduct of the hydrogen evolution corrosion reaction. This is consistent with the SEM image of the zinc electrode in Example 1 after immersion in an APG-added ZnSO4 electrolyte for 10 days. Figure 3 a) and b) show that the electrode surface is smooth and flat, with no obvious byproducts generated, and no obvious Zn4SO4(OH)6·5H2O peak appears in the XRD pattern. This indicates that the addition of APG enhances the zinc electrode's resistance to hydrogen evolution corrosion and reduces the generation of byproducts.

[0053] Figure 4a and b show the morphology of zinc deposited on the copper current collector in the ZnSO4 electrolyte of Comparative Example 1. It can be seen that the zinc flakes deposited on the surface of the copper current collector are disordered and mainly grow vertically. After long-term cycling, they will develop into zinc dendrites, which will pierce the separator and cause the battery to short-circuit. In contrast, the morphology of zinc deposition on the copper current collector in the ZnSO4 electrolyte with APG added in Example 1 is shown in Figure 1. Figure 5 (a) and (b) it can be clearly seen that the zinc sheet deposited on the surface of the copper current collector is flat and mainly grows horizontally, indicating that the addition of APG can induce the horizontal deposition of zinc sheet, mainly growing on the (002) crystal plane, and reducing the formation of dendrites.

[0054] For zinc electrodes, in Comparative Example 1, no additives were used. Figure 6 ) and Example 1 with added APG ( Figure 7 The corrosion potential (LSV) of the zinc electrode was evaluated using a ZnSO4 electrolyte. The results showed that the addition of APG increased the LSV and decreased the corrosion current, indicating that the addition of APG enhanced the corrosion resistance of the zinc electrode.

[0055] Using Comparative Example 1 without additives ( Figure 8 ) and Example 1 with added APG ( Figure 9 Zinc symmetric cells were assembled using ZnSO4 electrolyte and their cycle performance was tested. The results showed that the addition of APG significantly improved the battery cycle performance; the cycle life of the example was 28 times that of the control group.

[0056] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. An alkyl glycoside based aqueous zinc ion battery electrolyte, characterized in that: The electrolyte comprises solvent water, electrolyte and additive; the additive is alkyl glycoside, and its structural general formula is as follows: Wherein, n is the polymerization degree, and R is alkyl; In the alkyl glycoside, the polymerization degree n is 1-3, and R is C8-C16 alkyl.

2. The alkyl glycoside-based aqueous zinc-ion battery electrolyte according to claim 1, characterized in that: In the electrolyte, the mass fraction of the additive is 0.01-30%.

3. The alkyl glycoside-based aqueous zinc-ion battery electrolyte of claim 1, wherein: The electrolyte is any one or a combination of two or more of zinc sulfate, zinc chloride and zinc trifluoromethane sulfonate.

4. The alkyl glycoside-based aqueous zinc-ion battery electrolyte of claim 1, wherein: In the electrolyte, the molar concentration of the electrolyte is 1-3 mol / L.

5. A process for the preparation of the aqueous electrolyte for zinc ion batteries of alkyl glycoside class according to any one of claims 1 to 4, characterized by: The preparation method comprises the following steps: (1) dissolving the electrolyte in solvent water to obtain a water-based zinc ion battery electrolyte; (2) dissolving the alkyl glycoside additive in the water-based zinc ion battery electrolyte obtained in step (1) to obtain the alkyl glycoside water-based zinc ion battery electrolyte.

6. Application of the alkyl glycoside water-based zinc ion battery electrolyte in any one of claims 1-4 in a water-based zinc ion battery or a zinc ion electrochemical energy storage device.

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