A composite additive for aqueous zinc ion battery electrolyte and application thereof

Abstract

The application belongs to the technical field of zinc ion batteries, and particularly relates to a composite additive for an aqueous zinc ion battery electrolyte and application thereof. In order to solve the problems of dendrites, hydrogen evolution and corrosion of ZIBs, the application provides a new composite electrolyte additive for improving the performance of the aqueous zinc ion battery, i.e. a polyvinyl alcohol (PVA) and polydextrose (PD) composite electrolyte additive. The electrolyte additive used in the application overcomes the disadvantages of traditional electrolyte additives, and can significantly regulate and improve the performance of ZIBs while maintaining low cost and high ion transmission capacity. The electrolyte additive and the ZIBs composite electrolyte prepared by using the electrolyte additive are conducive to promoting the application of ZIBs in industrial production, and provide strong support for the application of ZIBs in practical application and daily life.

Description

Technical Field

[0001] This invention belongs to the field of zinc-ion battery technology, specifically relating to a composite additive for aqueous zinc-ion battery electrolytes and its application. Background Technology

[0002] With the continuous development of industrialization, traditional fossil fuels can no longer meet the ever-growing energy demands of human society, and the global energy structure is at a crucial juncture of upgrading and transformation. Electricity, as a renewable energy source, has become a powerful alternative to fossil fuels and is gradually taking a dominant position in the energy structure. Therefore, developing new energy storage devices that are economical, stable, efficient, and long-lasting has become a current research hotspot.

[0003] Lithium-ion batteries (LIBs) are currently the most widely used type of rechargeable battery, showing great market potential in consumer electronics and electric vehicles. However, they still have the following limitations: (1) Li is relatively reactive and organic electrolytes are toxic and flammable, leading to certain safety hazards in the production and use of LIBs; (2) Lithium resources are unevenly distributed worldwide, and low lithium reserves will be detrimental to the strategic security of energy storage; (3) The demand for LIBs has surged, and the supply of raw materials is insufficient, leading to an increase in the manufacturing cost of LIBs. Therefore, finding alternatives to LIBs has become a topic worthy of consideration.

[0004] Aqueous zinc-ion batteries (ZIBs), as a novel energy storage device, are expected to become a substitute for LIBs, solving their safety and high cost problems. ZIBs have the following advantages: (1) High safety: ZIBs can use aqueous electrolytes, avoiding the safety hazards and biotoxicity of organic electrolytes after leakage; (2) Excellent performance: Zinc anodes have high volumetric capacity and long cycle life; (3) Strong strategic importance: Zinc metal resources are extremely abundant, making ZIBs highly strategically secure. However, ZIBs also have some shortcomings: (1) Zinc ions will form uneven deposition on the zinc anode during operation; (2) Water, as the electrolyte solvent, will decompose and release hydrogen gas during battery charging and discharging; (3) The electrodes are susceptible to electrochemical corrosion due to the current during operation. These shortcomings result in a short service life of ZIBs, thus limiting their practical application. Therefore, the dendrite, hydrogen evolution, and corrosion problems of ZIBs urgently need to be solved.

[0005] Currently, existing research has focused on electrolytes to address issues such as dendrite formation, hydrogen evolution, and corrosion in zinc-ion batteries. The main approach involves introducing electrolyte additives, such as organic acids, phosphates, and polysaccharides, which can effectively alleviate these problems. However, this approach still has certain drawbacks: (1) a single electrolyte additive cannot simultaneously solve the dendrite formation, hydrogen evolution, and corrosion problems faced by zinc-ion batteries, and its effect on improving battery performance is limited; (2) excessively high concentrations of electrolyte additives lead to a high cost-to-price ratio, increasing the overall cost of the battery (e.g., Chinese invention patents CN117673501A and CN117199553A); (3) due to the strong electrostatic bonding between zinc ions and additive molecules, the ionic conductivity of the composite electrolyte is significantly reduced, failing to meet the actual needs of the battery. Therefore, it is necessary to develop new electrolyte additives for aqueous zinc-ion batteries to improve their performance while maintaining the economic and environmental advantages of aqueous zinc-ion batteries. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention proposes a composite additive for aqueous zinc-ion battery electrolytes, namely a composite electrolyte additive of polyvinyl alcohol (PVA) and polydextrose (PD). This additive improves the performance of aqueous zinc-ion batteries while maintaining their economic and environmental advantages.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of the present invention provides a composite electrolyte additive, the additive comprising polyvinyl alcohol (PVA) and polydextrose (PD).

[0009] The second aspect of this invention provides the application of the composite electrolyte additive described in the first aspect in an aqueous zinc-ion battery.

[0010] This invention provides a novel composite electrolyte additive for improving the performance of aqueous zinc-ion batteries: a PVA-PD composite electrolyte additive. PVA is a water-soluble polymer formed by the alcoholysis of polyvinyl acetate. Each repeating unit in its molecular chain contains a hydroxyl functional group. Due to its numerous hydroxyl groups, PVA can form a large number of hydrogen bonds after dissolving in water, thus exhibiting good hydrophilicity. Furthermore, its low price and non-toxicity make it a suitable choice as an inexpensive electrolyte additive. PD is a polymer formed by the dehydration condensation reaction of glucose. Thanks to the multi-hydroxyl structure of its monomer glucose, PD possesses abundant hydroxyl functional groups. Through a series of studies, this invention has found that PVA, as an additive, can be adsorbed onto the surface of the zinc electrode to regulate the dendrite deposition of ZIBs and inhibit corrosion; PD, as an additive, is beneficial for promoting Zn... 2+The desolvation process effectively reduces hydrogen evolution; when the two are combined, the potential difference between zinc deposition and stripping can be effectively reduced, thereby achieving faster reaction kinetics. Therefore, this invention utilizes the multi-hydroxyl characteristics of PVA and PD by dissolving them together in the electrolyte to prepare a novel aqueous zinc-ion battery composite electrolyte.

[0011] A third aspect of this invention provides an aqueous zinc-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the electrolyte includes a zinc salt and the additives described in the first aspect. The electrolyte is prepared by a stepwise dilution method.

[0012] Preferably, the concentration of polyvinyl alcohol in the electrolyte is 1.0 × 10⁻⁶. -10 -0.1 g / L, wherein the concentration of the polydextrose in the electrolyte is 0.005-0.1 M.

[0013] Preferably, the zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, zinc nitrate, zinc fluoride, zinc hexafluoroate, zinc trifluoromethanesulfonate, zinc bis(trifluoromethanesulfonyl)imide, and zinc tetrafluoroborate.

[0014] Preferably, the concentration of the zinc salt in the electrolyte is 0.001-5 mol / L.

[0015] Preferably, the positive electrode is selected from at least one of vanadium-based compounds, manganese-based compounds, disulfides, metal-based spinel materials, Prussian blue derivatives, conductive polymers, polyanionic compounds, carbonyl compounds, triphenylamine derivatives, nitro oxyethers, and imine compounds.

[0016] Preferably, the negative electrode is selected from one of zinc sheet, zinc plate, zinc powder, zinc foam, and zinc alloy materials.

[0017] Preferably, the diaphragm is selected from one of glass fiber, filter paper, aqueous polyolefin diaphragm, cellulose-based diaphragm, inorganic nanomaterial modified diaphragm, polymer electrolyte diaphragm, and composite material diaphragm.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This invention discloses a novel composite electrolyte additive for improving the performance of aqueous zinc-ion batteries, namely, a PVA-PD composite electrolyte additive. The electrolyte additive selected in this invention overcomes the drawbacks of traditional electrolyte additives, maintaining low cost and high ion transport capacity while significantly regulating and improving the performance of ZIBs. This electrolyte additive and the ZIBs composite electrolyte prepared using it are beneficial for promoting the application of ZIBs in industrial production, providing strong support for the practical and daily applications of ZIBs. Specifically, this invention has the following advantages:

[0020] (1) The composite electrolyte additive can effectively control dendrite formation, hydrogen evolution and corrosion problems of aqueous zinc-ion batteries.

[0021] (2) Compared with similar organic additives, the amount of additives added to this composite electrolyte is low and will not affect the ionic conductivity of the original electrolyte.

[0022] (3) The composite electrolyte additive can reduce the potential difference between zinc deposition and stripping to achieve faster reaction kinetics. Attached Figure Description

[0023] Figure 1 For comparison of SEM images from Example 1 and Comparative Examples 1-3;

[0024] Figure 2 This is a comparison chart of the ionic conductivity in the electrolytes of Example 2 and Comparative Example 4;

[0025] Figure 3 A comparison graph showing the hydrogen evolution curves of zinc metal in the electrolytes of Example 3 and Comparative Example 5;

[0026] Figure 4 A comparison of cyclic voltammetry curves of the platinum electrode in the electrolytes of Example 4 and Comparative Example 6;

[0027] Figure 5 The graph shows a comparison of the cycle performance of symmetrical batteries using Example 5 and Comparative Example 7. Detailed Implementation

[0028] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0030] Example 1: A composite additive for aqueous zinc-ion battery electrolyte (PVA-PD composite additive) and its preparation method

[0031] (1) Take 0.3g PVA (degree of hydrolysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) and add it to 30mL of deionized water. Stir magnetically for 90min in a water bath at 80℃ to obtain a 10g / L PVA solution.

[0032] (2) Take 50 μL of the above PVA solution and weigh 5.56 g of anhydrous zinc acetate. Add a small amount of deionized water and stir magnetically at room temperature until the zinc acetate is completely dissolved. Make up to 30 mL to obtain 1 M ZnAc2+ 5.0 × 10 -3 Aqueous zinc ion electrolyte with g / L PVA.

[0033] (3) Take 3 mL of 1M ZnAc2+ 5.0 × 10 -3 A water-based zinc ion electrolyte with a concentration of g / L PVA was prepared, and 5.004 g of anhydrous zinc acetate was added. After dissolving in water, the solution was stirred thoroughly at room temperature for 10 min at a stirring speed of 400 r / min, and then brought to a final volume of 30 mL to obtain 1 M ZnAc2+ 5.0 × 10 g PVA. -4 Aqueous zinc ion electrolyte containing g / LPVA additive and PVA additive.

[0034] (4) Repeat step (3) twice to obtain 1M ZnAc2+5.0×10 -6 Aqueous zinc ion electrolyte containing g / L PVA and PVA additive.

[0035] (5) Dissolve 0.1141 g of PD (molecular weight: 342.297) in the electrolyte of step (4) to obtain 1 M ZnAc2+ 5.0 × 10 -6 Aqueous zinc ion electrolyte containing PD-PVA composite additive (g / LPVA + 0.01M PD).

[0036] (6) Add 900 μL of the prepared aqueous zinc ion electrolyte containing PD-PVA composite additive to the electrolytic cell to assemble a Zn||Zn symmetric cell. Then, at 2 mA·cm -2 Current density and 1 mAh·cm -2 The zinc electrode was subjected to 120 cycles at the deposition capacity, then removed, washed and dried, and characterized by SEM.

[0037] Example 2: A composite additive for aqueous zinc-ion battery electrolyte (PVA-PD composite additive) and its preparation method

[0038] (1) Take 0.3g PVA (degree of hydrolysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) and add it to 30mL of deionized water. Stir magnetically for 90min in a water bath at 80℃ to obtain a 10g / L PVA solution.

[0039] (2) Take 50 μL of the above PVA solution and weigh 11.12 g of anhydrous zinc acetate. Add a small amount of deionized water and stir magnetically at room temperature until the zinc acetate is completely dissolved. Make up to 30 mL to obtain 2M ZnAc2+ 5.0 × 10 -3 Aqueous zinc ion electrolyte with g / L PVA.

[0040] (3) Take 3 mL of 2M ZnAc2+ 5.0 × 10 -3 A water-based zinc ion electrolyte with a concentration of g / L PVA was prepared, and 5.004 g of anhydrous zinc acetate was added. After dissolving in water, the solution was stirred thoroughly at room temperature for 10 min at a stirring speed of 400 r / min, and then brought to a final volume of 30 mL to obtain 2MZnAc2+ 5.0 × 10 g PVA. -4 Aqueous zinc ion electrolyte containing g / LPVA additive and PVA additive.

[0041] (4) Repeat step (3) 5 times to obtain 2M ZnAc2+5.0×10 -9 Aqueous zinc ion electrolyte containing g / L PVA and PVA additive.

[0042] (5) Dissolve 0.1141 g of PD (molecular weight: 342.297) in the electrolyte of step (4) to obtain 2M ZnAc2+ 5.0×10 -9 Aqueous zinc ion electrolyte containing PD-PVA composite additive (g / LPVA + 0.01M PD).

[0043] (6) Measure the conductivity of the aqueous zinc ion electrolyte containing PD-PVA composite additive.

[0044] Example 3: A composite additive for aqueous zinc-ion battery electrolyte (PVA-PD composite additive) and its preparation method

[0045] (1) Take 0.3g PVA (degree of hydrolysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) and add it to 30mL of deionized water. Stir magnetically for 90min in a water bath at 80℃ to obtain a 10g / L PVA solution.

[0046] (2) Take 50 μL of the above PVA solution, add a small amount of deionized water, then weigh 4.103 g of sodium acetate trihydrate and dissolve it in the solution. Stir thoroughly at room temperature for 10 min at a stirring speed of 400 r / min. After making up to 30 mL, you will get 1 M NaAc + 5.0 × 10⁻⁶ ppm. - 3 A NaAc electrolyte containing g / L PVA additive.

[0047] (3) Take 3 mL of 1M NaAc + 5.0 × 10⁻⁶ -3 A 1 g / L PVA electrolyte was prepared, and 3.693 g of sodium acetate trihydrate was added. After dissolving in water, the solution was stirred thoroughly at room temperature for 10 min at a stirring speed of 400 r / min, and then brought to a final volume of 30 mL to obtain 1 M NaAc + 5.0 × 10 g PVA electrolyte. -4 A NaAc electrolyte containing g / L PVA additive.

[0048] (4) Repeat step (3) twice to obtain 1M NaAc + 5.0 × 10⁻⁶. -6 A NaAc electrolyte containing g / L PVA additive.

[0049] (5) Dissolve 0.1141 g of PD (molecular weight: 342.297) in the electrolyte of step (4) to obtain 1 M NaAc + 5.0 × 10⁻⁶ ppm. -6 A NaAc electrolyte containing PD-PVA composite additives and g / LPVA + 0.01M PD.

[0050] (6) Linear voltammetry curve scanning test was performed on the obtained NaAc electrolyte containing PD-PVA composite additive.

[0051] Example 4: A composite additive for aqueous zinc-ion battery electrolyte (PVA-PD composite additive) and its preparation method

[0052] (1) Take 0.3g PVA (degree of hydrolysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) and add it to 30mL of deionized water. Stir magnetically for 90min in a water bath at 80℃ to obtain a 10g / L PVA solution.

[0053] (2) Take 50 μL of the above PVA solution and weigh 11.12 g of anhydrous zinc acetate. Add a small amount of deionized water and stir magnetically at room temperature until the zinc acetate is completely dissolved. Make up to 30 mL to obtain 2M ZnAc2+ 5.0 × 10 -3 Aqueous zinc ion electrolyte containing g / L PVA and PVA additive.

[0054] (3) Dissolve 1.141 g of PD (molecular weight: 342.297) in the electrolyte of step (2) to obtain 2M ZnAc2+ 5.0×10 -3 Aqueous zinc ion electrolyte containing PD-PVA composite additive (g / LPVA + 0.1M PD).

[0055] (4) Cyclic voltammetry curve scanning tests were performed on the obtained aqueous zinc ion electrolyte containing PD-PVA composite additive.

[0056] Example 5: A composite additive for aqueous zinc-ion battery electrolyte (PVA-PD composite additive) and its preparation method

[0057] (1) Take 0.3g PVA (degree of hydrolysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) and add it to 30mL of deionized water. Stir magnetically for 90min in a water bath at 80℃ to obtain a 10g / L PVA solution.

[0058] (2) Take 50 μL of the above PVA solution and weigh 5.56 g of anhydrous zinc acetate. Add a small amount of deionized water and stir magnetically at room temperature until the zinc acetate is completely dissolved. Make up to 30 mL to obtain 1 M ZnAc2+ 5.0 × 10 -3 Aqueous zinc ion electrolyte containing g / L PVA and PVA additive.

[0059] (3) Take 3 mL of 1M ZnAc2+ 5.0 × 10 -3 A water-based zinc ion electrolyte with a concentration of g / L PVA was prepared, and 5.004 g of anhydrous zinc acetate was added. After dissolving in water, the solution was stirred thoroughly at room temperature for 10 min at a stirring speed of 400 r / min, and then brought to a final volume of 30 mL to obtain 1 M ZnAc2+ 5.0 × 10 g PVA. -4 Aqueous zinc ion electrolyte containing g / LPVA additive and PVA additive.

[0060] (4) Repeat step (3) twice to obtain 1M ZnAc2+5.0×10 -6 Aqueous zinc ion electrolyte containing g / L PVA and PVA additive.

[0061] (5) Dissolve 0.2282 g of PD (molecular weight: 342.297) in the electrolyte of step (4) to obtain 1 M ZnAc2+ 5.0 × 10 -6 Aqueous zinc ion electrolyte containing PD-PVA composite additive (g / LPVA + 0.02M PD).

[0062] (6) Drop 400 μL of aqueous zinc ion electrolyte containing PD-PVA composite additive onto the glass fiber separator, and then assemble the symmetrical battery in the following order: negative electrode shell - spring plate - gasket - negative electrode zinc plate - separator - electrolyte - positive electrode zinc plate - positive electrode shell. Then, at 1 mA·cm⁻¹... -2 The current density and 0.5 mAh·cm -2 Battery cycle testing was conducted at the deposition capacity.

[0063] Comparative Example 1: An additive for aqueous zinc-ion battery electrolyte (PVA additive) and its preparation method

[0064] (1) Take 0.3g PVA (degree of hydrolysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) and add it to 30mL of deionized water. Stir magnetically for 90min in a water bath at 80℃ to obtain a 10g / L PVA solution.

[0065] (2) Take 50 μL of the above PVA solution and weigh 5.56 g of anhydrous zinc acetate. Add a small amount of deionized water and stir magnetically at room temperature until the zinc acetate is completely dissolved. Make up to 30 mL to obtain 1 M ZnAc2+ 5.0 × 10 -3 Aqueous zinc ion electrolyte containing g / L PVA and PVA additive.

[0066] (3) Take 3 mL of 1M ZnAc2+ 5.0 × 10 -3 A water-based zinc ion electrolyte with a concentration of g / L PVA was prepared, and 5.004 g of anhydrous zinc acetate was added. After dissolving in water, the solution was stirred thoroughly at room temperature for 10 min at a stirring speed of 400 r / min, and then brought to a final volume of 30 mL to obtain 1 M ZnAc2+ 5.0 × 10 g PVA. -4 Aqueous zinc ion electrolyte containing g / LPVA additive and PVA additive.

[0067] (4) Repeat step (3) twice to obtain 1M ZnAc2+5.0×10 -6 Aqueous zinc ion electrolyte containing g / L PVA and PVA additive.

[0068] (5) Add 900 μL of the prepared aqueous zinc ion electrolyte containing PVA additive to the electrolytic cell to assemble a Zn||Zn symmetric cell. Then, at 2 mA·cm⁻¹... -2 Current density and 1 mAh·cm -2 The zinc electrode was subjected to 120 cycles at the deposition capacity, then removed, washed and dried, and characterized by SEM.

[0069] Comparative Example 2: An aqueous zinc-ion battery electrolyte additive (PD additive) and its preparation method

[0070] (1) Weigh 0.1141g of PD (molecular weight: 342.297), add a small amount of deionized water, and stir magnetically at room temperature until the PD is completely dissolved.

[0071] (2) Add 5.56g of anhydrous zinc acetate to step (1), dissolve it in water, stir it thoroughly at room temperature for 10min at a stirring speed of 400r / min, and then adjust the volume to 30mL to obtain an aqueous zinc ion electrolyte containing PD additive of 1M ZnAc2+0.01M PD.

[0072] (3) Add 900 μL of the aqueous zinc ion electrolyte containing PD additives prepared in the electrolytic cell to assemble a Zn||Zn symmetric cell. Then, at 2 mA·cm -2 Current density and 1 mAh·cm -2 The zinc electrode was subjected to 120 cycles at the deposition capacity, then removed, washed and dried, and characterized by SEM.

[0073] Comparative Example 3

[0074] (1) Take 5.56g of anhydrous zinc acetate and add it to deionized water. Stir thoroughly at room temperature for 10min at a stirring speed of 400r / min, and then adjust the volume to 30mL to obtain 1M ZnAc2 electrolyte.

[0075] (2) Add 900 μL of the prepared pure ZnAc2 electrolyte to the electrolytic cell to assemble a Zn||Zn symmetric cell. Then, at 2 mA.cm -2 The current density and 1 mAh.cm -2 The zinc electrode was subjected to 120 cycles at the deposition capacity, then removed, washed and dried, and characterized by SEM.

[0076] Comparative Example 4

[0077] (1) Take 11.12g of anhydrous zinc acetate and add it to deionized water. Stir thoroughly at room temperature for 10min at a stirring speed of 400r / min, and then adjust the volume to 30mL to obtain 2M ZnAc2 electrolyte.

[0078] (2) Measure the conductivity of the obtained pure ZnAc2 electrolyte.

[0079] Comparative Example 5

[0080] (1) Take 4.103g of sodium acetate trihydrate and add it to deionized water. Stir it thoroughly at room temperature for 10min at a stirring speed of 400r / min, and then make up to 30mL to obtain 1M NaAc electrolyte.

[0081] (2) Linear voltammetry curves were scanned on the obtained pure NaAc electrolyte.

[0082] Comparative Example 6

[0083] (1) Take 11.12g of anhydrous zinc acetate and add it to deionized water. Stir thoroughly at room temperature for 10min at a stirring speed of 400r / min, and then adjust the volume to 30mL to obtain 2M ZnAc2 electrolyte.

[0084] (2) Cyclic voltammetry curves were scanned on the obtained pure ZnAc2 electrolyte.

[0085] Comparative Example 7

[0086] (1) Take 5.56g of anhydrous zinc acetate and add it to deionized water. Stir thoroughly at room temperature for 10min at a stirring speed of 400r / min, and then adjust the volume to 30mL to obtain 1M ZnAc2 electrolyte.

[0087] (2) Drop 400 μL of pure ZnAc2 electrolyte onto the glass fiber separator, and then assemble the symmetrical battery in the following order: negative electrode shell - spring plate - gasket - negative electrode zinc plate - separator - electrolyte - positive electrode zinc plate - positive electrode shell. Then, at 1 mA·cm⁻¹... -2 The current density and 0.5 mAh·cm -2 Battery cycle testing was conducted at the deposition capacity.

[0088] like Figure 1 As shown, in Example 1, the addition of the PVA-PD composite additive resulted in uniform dendrite growth on the electrode surface with minimal pitting corrosion. In Comparative Example 1, the addition of the PVA additive still resulted in some corrosion on the electrode surface. In Comparative Example 2, the addition of the PD additive led to numerous pitting corrosion pits on the electrode surface. The electrode surface corrosion in Comparative Example 3 was extremely severe. These results demonstrate that the PVA-PD composite additive can effectively regulate dendrite growth and inhibit electrode corrosion.

[0089] like Figure 2 As shown, compared to the pure ZnAc2 electrolyte in Comparative Example 4, the addition of PVA-PD composite electrolyte additive in Example 2 had no effect on the ionic conductivity of the ZnAc2 electrolyte.

[0090] like Figure 3 As shown, the hydrogen evolution potential of the electrolyte in Example 3 is higher when the PVA-PD composite additive is present, which proves that the hydrogen evolution reaction is inhibited (NaAc electrolyte was used for testing to avoid the influence of zinc ion deposition behavior on the hydrogen evolution potential).

[0091] like Figure 4As shown, after adding the PVA-PD composite electrolyte additive in Example 4, the corresponding onset potentials for Zn deposition / stripping in the cyclic voltammetry curve of the ZnAc2 electrolyte were -1.09 / 0.27V. Compared with -1.09 / 0.30V of the pure ZnAc2 electrolyte in Comparative Example 6, the potential difference between deposition and stripping was smaller, proving that Zn deposition and stripping had faster kinetics at this time.

[0092] like Figure 5 As shown, the Zn||Zn symmetric battery in Example 5 achieved a cycle life of approximately 670 hours, which is more than double that of the 300 hours in Comparative Example 7. This indicates that the PD-PVA composite additive can significantly increase the cycle life of aqueous zinc-ion batteries.

[0093] In summary, the composite electrolyte additive (PVA-PD) selected in this invention can effectively suppress dendrite formation, hydrogen evolution, and corrosion simultaneously. Furthermore, the low addition amounts of both additives have minimal impact on battery production costs and do not affect the conductivity of the original electrolyte.

[0094] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. Use of a composite electrolyte additive in aqueous zinc-ion batteries, characterized in that, The additive comprises polyvinyl alcohol and polydextrose; the concentration of the polyvinyl alcohol in the electrolyte is 1.0 x 10 -10 -0.1 g / L, and the concentration of the polydextrose in the electrolyte is 0.005-0.1 M.

2. An aqueous zinc-ion battery, characterized in that, The aqueous zinc ion battery is composed of a positive electrode, a negative electrode, a separator and an electrolyte, the electrolyte comprises a zinc salt and an additive, the additive comprises polyvinyl alcohol and polydextrose; the concentration of the polyvinyl alcohol in the electrolyte is 1.0x10 -10 -0.1 g / L, and the concentration of the polydextrose in the electrolyte is 0.005-0.1 M.

3. The aqueous zinc-ion battery of claim 2, wherein, The zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, zinc nitrate, zinc fluoride, zinc hexafluoride, zinc trifluoromethane sulfonate, zinc bistrifluoromethane sulfonimide, zinc tetrafluoroborate.

4. The aqueous zinc-ion battery of claim 2, wherein, The concentration of the zinc salt in the electrolyte is 0.001-5 mol / L.

5. The aqueous zinc-ion battery of claim 2, wherein, The positive electrode is selected from at least one of vanadium-based compounds, manganese-based compounds, disulfides, metal-based spinel materials, prussian blue derivatives, conductive polymers, polyanion compounds, carbonyl compounds, triphenylamine derivatives, nitro-based oxyanion ethers and imine compounds.

6. The aqueous zinc-ion battery of claim 2, wherein, The negative electrode is selected from one of zinc sheet, zinc plate, zinc powder, foamed zinc, zinc alloy material.

7. The aqueous zinc ion battery of claim 2, wherein, The separator is selected from one of glass fiber, filter paper, water-based polyolefin separator, cellulose-based separator, inorganic nanomaterial modified separator, polymer electrolyte separator, composite material separator.

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