Composite additive for aqueous zinc ion battery electrolyte and application thereof

Abstract

The invention 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 of the composite additive. In order to solve the problems of dendritic crystal, hydrogen evolution, corrosion and the like of ZIBs, the invention provides a novel composite electrolyte additive for improving the performance of an aqueous zinc ion battery, namely a polyvinyl alcohol (PVA) and polydextrose (PD) composite electrolyte additive. According to the electrolyte additive selected by the invention, the defects of the traditional electrolyte additive are overcome, and the performance of ZIBs can be remarkably regulated and improved while low cost and high ion transmission capability are maintained. According to the electrolyte additive and the ZIBs composite electrolyte prepared from the electrolyte additive, ZIBs can be applied to the field of industrial production, and powerful support is provided for application of ZIBs in practical application and daily life.

Description

Technical Field

[0001] The invention belongs to the technical field of zinc ion batteries, and in particular relates to a composite additive for aqueous zinc ion battery electrolyte and application thereof. Background Art

[0002] With the continuous development of industrialization, traditional fossil energy can no longer meet the growing energy demand of human society, and the global energy structure is at an important node of upgrading and transformation. Electricity, as a renewable energy source, has become a powerful substitute for fossil energy and gradually occupied a dominant position in the energy structure. The development of new energy storage devices that are economical, stable, efficient and long-life has become a current research hotspot.

[0003] Lithium-ion batteries (LIBs) are the most widely used type of secondary batteries, showing great market prospects in consumer electronics and electric vehicles. However, they still have the following limitations: (1) The Li element is relatively active and the organic electrolyte is toxic and flammable, which leads to certain safety hazards in the production and use of LIBs; (2) The distribution of lithium resources is uneven worldwide, and the low reserves of lithium resources will be detrimental to the strategic security of energy storage; (3) The demand for LIBs has increased sharply, and the supply of raw materials is insufficient, resulting in an increase in the manufacturing cost of LIBs. Therefore, finding a substitute for LIBs has become a topic worth considering.

[0004] As a new type of energy storage device, aqueous zinc-ion batteries (ZIBs) are expected to become an alternative to LIBs and solve the problems of safety and high cost faced by LIBs. ZIBs have the following advantages: (1) High safety: ZIBs can use aqueous electrolytes, avoiding the safety hazards and biological toxicity of organic electrolytes after leakage; (2) Excellent performance: The zinc negative electrode has the characteristics of high volume capacity and long cycle life; (3) Strong strategic significance: Zinc metal resources are extremely abundant, making ZIBs have high strategic security. However, ZIBs also have some shortcomings: (1) During operation, zinc ions will produce uneven deposition on the zinc negative electrode; (2) Water, as an electrolyte solvent, will decompose and release hydrogen during the battery charging and discharging process; (3) The electrode is susceptible to electrochemical corrosion because it is energized during operation. The above shortcomings lead to a short service life of ZIBs, which in turn limits their practical application. Therefore, the problems of dendrites, hydrogen evolution and corrosion of ZIBs need to be solved urgently.

[0005] At present, there have been studies that use electrolyte as a starting point to solve the problems of dendrite, hydrogen evolution and corrosion of ZIBs. The main solution involved is to introduce electrolyte additives, such as organic acids, phosphates and polysaccharide additives, which can effectively alleviate the above problems. However, there are still certain disadvantages: (1) It is difficult for a single electrolyte additive to simultaneously solve the problems of dendrite, hydrogen evolution and corrosion faced by ZIBs, and the effect on improving battery performance is limited; (2) Excessively high concentrations of electrolyte additives will lead to a high proportion of additive costs, resulting in an increase in the overall cost of the battery (such as 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, which cannot meet the actual needs of the battery. Therefore, it is necessary to develop new aqueous zinc ion battery electrolyte additives to improve the performance of aqueous zinc ion batteries while maintaining the advantages of economic and environmental protection. Summary of the invention

[0006] In order to overcome the deficiencies of the above-mentioned prior art, the present invention proposes an aqueous zinc ion battery electrolyte composite additive, namely, a polyvinyl alcohol (PVA) and polydextrose (PD) composite electrolyte additive, which improves the performance of aqueous zinc ion batteries while maintaining the economic and environmental advantages of aqueous zinc ion batteries.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

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

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

[0010] The present invention provides a new composite electrolyte additive for improving the performance of aqueous zinc ion batteries, namely, a PVA-PD composite electrolyte additive. Among them, PVA is a water-soluble high molecular polymer formed by the alcoholysis of polyvinyl acetate, and each repeated unit structure on its molecular chain contains a hydroxyl functional group. Thanks to its numerous hydroxyl groups, PVA can form a large number of hydrogen bonds after dissolving in water. Therefore, PVA has good hydrophilicity. In addition, due to its advantages such as low price and non-toxicity, it is a suitable choice as a cheap electrolyte additive. PD is a polymer formed by the dehydration condensation reaction of glucose. Thanks to the polyhydroxy structure of its polymerized monomer glucose, PD has rich hydroxyl functional groups. Through a series of studies, the present invention found that: PVA as an additive can be adsorbed on the surface of the zinc electrode to achieve the regulation of the dendrite deposition of ZIBs and inhibit the occurrence of corrosion; PD as an additive is beneficial to promote Zn 2+The desolvation process of PVA and PD can effectively reduce the amount of 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, the present invention prepares a novel aqueous zinc ion battery composite electrolyte by dissolving PVA and PD into the electrolyte together and making full use of the characteristics of polyhydroxyl groups.

[0011] The third aspect of the present invention provides an aqueous zinc ion battery, the aqueous zinc ion battery comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the electrolyte comprises a zinc salt and the additive 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 -10 -0.1g / L, and the concentration of polydextrose in the electrolyte is 0.005-0.1M.

[0013] Preferably, the zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, zinc nitrate, zinc fluoride, zinc hexafluoride, zinc trifluoromethanesulfonate, zinc bistrifluoromethanesulfonyl 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, polyanion compounds, carbonyl compounds, triphenylamine derivatives, nitrooxyethers and imine compounds.

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

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

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention discloses a new composite electrolyte additive for improving the performance of aqueous zinc ion batteries, namely, a PVA-PD composite electrolyte additive. The electrolyte additive selected by the present invention overcomes the drawbacks of traditional electrolyte additives, and while maintaining low cost and high ion transmission capacity, it can also significantly regulate and improve the performance of ZIBs. The electrolyte additive and the ZIBs composite electrolyte prepared using the electrolyte additive are conducive to promoting the application of ZIBs in the field of industrial production, and provide strong support for the application of ZIBs in practical applications and daily life. Specifically, the present invention has the following advantages:

[0020] (1) The composite electrolyte additive can effectively regulate the dendrite, hydrogen evolution and corrosion problems of aqueous zinc-ion batteries at the same time.

[0021] (2) Compared with similar organic additives, the amount of the composite electrolyte additive added 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 2 It is a comparison diagram of ion conductivity in the electrolyte of Example 2 and Comparative Example 4;

[0025] Figure 3 It is a comparison diagram of hydrogen evolution curves of zinc metal in the electrolyte of Example 3 and Comparative Example 5;

[0026] Figure 4 It is a comparison diagram of cyclic voltammetry curves of platinum electrode in the electrolyte of Example 4 and Comparative Example 6;

[0027] Figure 5 The figure is a comparison chart of the cycle performance of the symmetrical batteries using Example 5 and Comparative Example 7. DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention are further described below. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

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

[0031] (1) 0.3 g of PVA (degree of alcoholysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) was added to 30 mL of deionized water and stirred under magnetic stirring in a water bath at 80° C. for 90 min to obtain a 10 g / 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. The volume is fixed to 30 mL to obtain 1M ZnAc2+5.0×10 -3 g / L PVA aqueous zinc ion electrolyte.

[0033] (3) Take 3 mL of 1 M ZnAc2 + 5.0 × 10 -3 g / L PVA aqueous zinc ion electrolyte, and add 5.004g anhydrous zinc acetate, dissolve in water, stir thoroughly for 10min at room temperature, stirring speed is 400r / min, and then dilute to 30mL to obtain 1MZnAc2+5.0×10 -4 g / LPVA containing PVA additive aqueous zinc ion electrolyte.

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

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

[0036] (6) 900 μL of the prepared aqueous zinc ion electrolyte containing the PD-PVA composite additive was added to the electrolytic cell to assemble a Zn||Zn symmetrical cell. -2 The current density and 1 mAh cm -2 The Zn electrode was then taken out, 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) 0.3 g of PVA (degree of alcoholysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) was added to 30 mL of deionized water and stirred under magnetic stirring in a water bath at 80° C. for 90 min to obtain a 10 g / 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. The volume is fixed to 30 mL to obtain 2M ZnAc2+5.0×10 -3 g / L PVA aqueous zinc ion electrolyte.

[0040] (3) Take 3 mL of 2M ZnAc2 + 5.0×10 -3 g / L PVA aqueous zinc ion electrolyte, and add 5.004g anhydrous zinc acetate, dissolve in water, stir thoroughly for 10min at room temperature, stirring speed is 400r / min, and then dilute to 30mL to obtain 2MZnAc2+5.0×10 -4 g / LPVA containing PVA additive aqueous zinc ion electrolyte.

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

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

[0043] (6) Measure the conductivity of the obtained aqueous zinc ion electrolyte containing the 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) 0.3 g of PVA (degree of alcoholysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) was added to 30 mL of deionized water and stirred under magnetic stirring in a water bath at 80° C. for 90 min to obtain a 10 g / L PVA solution.

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

[0047] (3) Take 3 mL of 1 M NaAc + 5.0 × 10 -3 g / L PVA electrolyte, and add 3.693g sodium acetate trihydrate, add water to dissolve, stir thoroughly for 10min at room temperature, stirring speed is 400r / min, and then dilute to 30mL to obtain 1MNaAc+5.0×10 -4 g / L PVA containing PVA additive NaAc electrolyte.

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

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

[0050] (6) A linear voltammetric 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) 0.3 g of PVA (degree of alcoholysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) was added to 30 mL of deionized water and stirred under magnetic stirring in a water bath at 80° C. for 90 min to obtain a 10 g / 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. The volume is fixed to 30 mL to obtain 2M ZnAc2+5.0×10 -3 g / L PVA containing PVA additive aqueous zinc ion electrolyte.

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

[0055] (4) A cyclic voltammetry curve scanning test was 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) 0.3 g of PVA (degree of alcoholysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) was added to 30 mL of deionized water and stirred under magnetic stirring in a water bath at 80° C. for 90 min to obtain a 10 g / 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. The volume is fixed to 30 mL to obtain 1M ZnAc2+5.0×10 -3 g / L PVA containing PVA additive aqueous zinc ion electrolyte.

[0059] (3) Take 3 mL of 1 M ZnAc2 + 5.0 × 10 -3 g / L PVA aqueous zinc ion electrolyte, and add 5.004g anhydrous zinc acetate, dissolve in water, stir thoroughly for 10min at room temperature, stirring speed is 400r / min, and then dilute to 30mL to obtain 1MZnAc2+5.0×10 -4 g / LPVA containing PVA additive aqueous zinc ion electrolyte.

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

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

[0062] (6) 400 μL of aqueous zinc ion electrolyte containing PD-PVA composite additive was dropped onto the glass fiber separator, and a symmetrical battery was assembled in the order of negative electrode shell-spring-gasket-negative zinc sheet-diaphragm-electrolyte-positive zinc sheet-positive electrode shell, and then the battery was charged at 1 mA cm -2 The current density and 0.5 mAh cm -2 The battery cycle test was carried out at a deposition capacity of .

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

[0064] (1) 0.3 g of PVA (degree of alcoholysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa.s) was added to 30 mL of deionized water and stirred under magnetic stirring in a water bath at 80° C. for 90 min to obtain a 10 g / 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. The volume is fixed to 30 mL to obtain 1M ZnAc2+5.0×10 -3 g / L PVA containing PVA additive aqueous zinc ion electrolyte.

[0066] (3) Take 3 mL of 1 M ZnAc2 + 5.0 × 10 -3 g / L PVA aqueous zinc ion electrolyte, and add 5.004g anhydrous zinc acetate, dissolve in water, stir thoroughly for 10min at room temperature, stirring speed is 400r / min, and then dilute to 30mL to obtain 1MZnAc2+5.0×10 -4 g / LPVA containing PVA additive aqueous zinc ion electrolyte.

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

[0068] (5) 900 μL of the prepared aqueous zinc ion electrolyte containing PVA additive was added to the electrolytic cell to assemble a Zn||Zn symmetrical cell. -2 The current density and 1 mAh cm -2 The Zn electrode was then taken out, 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 0.1141 g of PD (molecular weight: 342.297), add a small amount of deionized water, and stir magnetically at room temperature until PD is completely dissolved.

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

[0072] (3) 900 μL of the prepared aqueous zinc ion electrolyte containing PD additive was added to the electrolytic cell to assemble a Zn||Zn symmetrical cell. -2 The current density and 1 mAh cm -2 The Zn electrode was then taken out, washed and dried, and characterized by SEM.

[0073] Comparative Example 3

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

[0075] (2) Add 900 μL of the prepared pure ZnAc2 electrolyte into the electrolytic cell to assemble a Zn||Zn symmetrical cell. -2 The current density and 1mAh.cm -2 The Zn electrode was then taken out, washed and dried, and characterized by SEM.

[0076] Comparative Example 4

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

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

[0079] Comparative Example 5

[0080] (1) 4.103 g of sodium acetate trihydrate was added to deionized water, stirred for 10 min at room temperature at a stirring speed of 400 r / min, and then the volume was adjusted to 30 mL to obtain a 1 M NaAc electrolyte.

[0081] (2) The obtained pure NaAc electrolyte was subjected to a linear voltammetric scan.

[0082] Comparative Example 6

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

[0084] (2) The obtained pure ZnAc2 electrolyte was subjected to cyclic voltammetry curve scanning.

[0085] Comparative Example 7

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

[0087] (2) 400 μL of pure ZnAc2 electrolyte was dropped onto the glass fiber separator, and a symmetrical battery was assembled in the order of negative electrode shell-spring-gasket-negative zinc sheet-diaphragm-electrolyte-positive zinc sheet-positive electrode shell. -2 The current density and 0.5 mAh cm -2 The battery cycle test was carried out at a deposition capacity of .

[0088] like Figure 1 As shown, after adding the PVA-PD composite additive in Example 1, the electrode surface has uniform dendrite growth and pitting corrosion occurs very little. After adding the PVA additive in Comparative Example 1, there is still a certain amount of corrosion on the electrode surface. After adding the PD additive in Comparative Example 2, a large number of pitting pits appear on the electrode surface, and the electrode surface corrosion in Comparative Example 3 is extremely serious. The above results show that the PVA-PD composite additive can effectively regulate the growth of dendrites and inhibit electrode corrosion.

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

[0090] like Figure 3 As shown, from the perspective of hydrogen evolution potential, when the PVA-PD composite additive is present, the hydrogen evolution potential of the electrolyte in Example 3 is higher, proving that the hydrogen evolution reaction is suppressed (in order to avoid the influence of the deposition behavior of zinc ions on the hydrogen evolution potential, NaAc electrolyte is used for testing).

[0091] like Figure 4As shown, after the PVA-PD composite electrolyte additive is added in Example 4, the corresponding starting potential of Zn deposition / stripping in the cyclic voltammetry curve of the ZnAc2 electrolyte is -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 is smaller, proving that the deposition and stripping of Zn have faster kinetics at this time.

[0092] like Figure 5 As shown, the cycle life of the Zn||Zn symmetric battery in Example 5 reached about 670 h, which is more than twice as long as 300 h in Comparative Example 7, indicating 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) used in the present invention can effectively inhibit dendrites, hydrogen evolution and corrosion at the same time. At the same time, the low addition amount of the two additives has little effect on the increase of battery production cost and has no effect on the conductivity of the original electrolyte.

[0094] The embodiments of the present invention are 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 of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the protection scope of the present invention.

Claims

1. A composite electrolyte additive, characterized in that: The additives include polyvinyl alcohol and polydextrose.

2. Use of the composite electrolyte additive according to claim 1 in aqueous zinc ion batteries.

3. An aqueous zinc ion battery, characterized in that: The aqueous zinc ion battery consists of a positive electrode, a negative electrode, a separator and an electrolyte, and the electrolyte includes a zinc salt and the additive according to claim 1.

4. An aqueous zinc ion battery according to claim 3, characterized in that: The concentration of polyvinyl alcohol in the electrolyte is 1.0×10 -10 -0.1g / L, and the concentration of polydextrose in the electrolyte is 0.005-0.1M.

5. An aqueous zinc ion battery according to claim 3, characterized in that: The zinc salt is selected from at least one of zinc sulfate, zinc acetate, zinc chloride, zinc nitrate, zinc fluoride, zinc hexafluoride, zinc trifluoromethanesulfonate, zinc bistrifluoromethanesulfonyl imide, and zinc tetrafluoroborate.

6. An aqueous zinc ion battery according to claim 3, characterized in that: The concentration of the zinc salt in the electrolyte is 0.001-5 mol / L.

7. An aqueous zinc ion battery according to claim 3, characterized in that: 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, nitrooxyethers and imine compounds.

8. An aqueous zinc ion battery according to claim 3, characterized in that: The negative electrode is selected from one of zinc sheets, zinc plates, zinc powder, foamed zinc and zinc alloy materials.

9. An aqueous zinc ion battery according to claim 3, characterized in that: The diaphragm is selected from one of glass fiber, filter paper, water-based polyolefin diaphragm, cellulose-based diaphragm, inorganic nanomaterial modified diaphragm, polymer electrolyte diaphragm and composite material diaphragm.

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