5-azacytidine electrolyte capable of protecting zinc ion battery electrode

Abstract

The invention discloses an electrolyte capable of protecting an electrode of a zinc ion battery, 5-azacytidine is added into the electrolyte of the zinc ion battery, in the zinc deposition process, the 5-azacytidine is adsorbed on the surface of a zinc anode and adjusts a zinc ion solvation shell layer to inhibit growth of zinc dendrites in the circulation process, and the cycle life of the zinc ion battery is remarkably prolonged. The electrolyte provided by the invention is simple in formula and low in cost, the preparation process is simple to operate, and the cycle life and the cycle stability of the zinc ion battery prepared from the electrolyte provided by the invention are greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and more particularly, relates to a method for preparing an aqueous zinc-ion battery electrolyte. Background Art

[0002] Rechargeable batteries, as clean energy sources, are a key technology in the new energy field. They can provide energy storage and conversion for large-scale electronic instruments, equipment, and transportation vehicles, playing a positive role in achieving carbon neutrality. Lithium-ion batteries (LIBs) are widely used in various electronic devices due to their advantages such as high energy density and long cycle life. However, the limited reserves and high price of lithium resources, the low conductivity, toxicity, and flammability and explosion hazards of the organic electrolytes they use have greatly hindered the further large-scale application of lithium-ion batteries.

[0003] Rechargeable aqueous zinc-ion batteries (ZIBS), as a promising advanced energy storage system, have received increasing attention due to the low redox potential of Zn / Zn 2+ (-0.763V vs. standard hydrogen electrode), high theoretical capacity (820 mAh g -1 and 5854 mAh cm -3 ), low cost, environmental friendliness, abundant reserves of metallic zinc, and high operational safety. However, the implementation of this technology is restricted by adverse side reactions such as hydrogen evolution reaction, Zn corrosion and passivation, and Zn dendrites. These factors will lead to poor reversibility and shortened life of the battery. How to solve these problems has important research significance and application value.

[0004] So far, efforts have been made to develop various aqueous electrolytes with expanded electrochemical windows, strong electrostatic shell protection, improved flame retardancy, and highly stable electrode / electrolyte interfaces, including electrolyte additives, ionic liquid electrolytes, water-salt electrolytes, and hydrogel electrolytes. Among them, electrolyte additive engineering is a common and cost-effective method. Electrolyte additives can not only improve ionic conductivity by controlling the type and quantity of conductive ions but also expand the electrochemical window by suppressing oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In addition, electrolyte additives can form a strong and stable protective layer on the electrode surface, thereby inhibiting the growth of Zn dendrites and preventing cathode dissolution. Summary of the Invention

[0005] The main object of the present invention is to provide an electrolyte for zinc-ion batteries, which is different from ordinary electrolytes in that it can effectively protect the battery electrodes, inhibit the growth of zinc dendrites, and effectively improve the cycle life of zinc-ion batteries.

[0006] To achieve the above object, the present invention is realized through the following technical solutions:

[0007] An electrolyte that can protect the electrodes of an aqueous zinc-ion battery, the electrolyte comprising a solvent, a solute, and an additive 5-azacytidine.

[0008] Furthermore, the solute is a soluble zinc salt, specifically one or more of zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc fluoride, zinc hexafluoride, and zinc trifluoromethanesulfonate, with a concentration of 0.1 - 10 mol / L.

[0009] Furthermore, the solvent is water.

[0010] Furthermore, the concentration of the organic additive 5-azacytidine in the solvent is 0.1 - 5 g / L.

[0011] The beneficial effects of the present invention are as follows:

[0012] (1) In the present invention, 5-azacytidine is used as an additive for the electrolyte of an aqueous zinc-ion battery. By means of strong polar groups and multiple hydroxyl groups, the transport of zinc ions at the electrolyte interface is regulated, the solvation sheath structure of zinc ions is reconstructed, the reaction activity of free water is inhibited, the formation and growth of zinc dendrites are inhibited, hydrogen evolution and the generation of by-products are inhibited, and the long-term cycle stability of the zinc-ion battery is improved.

[0013] (2) In the present invention, 5-azacytidine is used as an electrolyte additive, which can effectively inhibit the growth of zinc dendrites on the surface of the zinc negative electrode and interfacial side reactions. As an organic compound containing rich lone pair electron groups and multiple hydroxyl groups, 5-azacytidine is inexpensive, environmentally friendly, and can be produced on a large scale, which is of great significance for realizing high-performance and long-cycle-stability aqueous zinc-ion batteries.

[0014] (3) The preparation formula of the electrolyte of the present invention is simple, and the preparation process is easy to operate. The prepared zinc-ion battery has effectively improved cycle life and cycle stability after electrochemical testing. Description of the Drawings

[0015] Figure 1 . The structural formula of 5-azacytidine.

[0016] Figure 2 . It is the surface of the electrode after 5 cycles of the zinc symmetric battery assembled with blank electrolyte 1 in Example 1.

[0017] Figure 3 . It is the surface of the electrode after 5 cycles of the zinc symmetric battery assembled with target electrolyte 2 in Example 1.

[0018] Figure 4 . It is the cycling condition of the full battery assembled with blank electrolyte 1 and target electrolyte 3 in Example 2 at a current density of 1000 mA / g. Detailed Embodiments

[0019] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0020] Example 1

[0021] Blank electrolyte 1:

[0022] The electrolyte is composed of a soluble zinc salt and deionized water. The zinc salt is zinc sulfate (ZnSO 4 )), and the concentration of zinc sulfate (ZnSO 4 ) is 1 mol / L, and the balance is water. The resulting electrolyte is blank electrolyte 1.

[0023] Target electrolyte 2:

[0024] The electrolyte is composed of a soluble zinc salt, 5-azacytidine, and deionized water. The zinc salt is zinc sulfate (ZnSO 4 ), where the concentration of zinc sulfate (ZnSO 4 ) is 1 mol / L, and the concentration of 5-azacytidine is 0.1 g / L, and the balance is water. The resulting electrolyte is target electrolyte 2.

[0025] The above electrolytes are assembled into a Zn / Zn symmetric battery for electrochemical testing. The assembly sequence is the negative electrode case, shrapnel, gasket, zinc sheet, glass fiber separator, zinc sheet, and positive electrode case. 100 microliters of electrolyte is dropped at the separator for each button battery.

[0026] The electrochemical testing of the Zn / Zn symmetric battery in this example is carried out on a NEWARE testing system, and the testing temperature is maintained at a constant temperature of 25 °C.

[0027] As Figure 1 shown is the surface morphology of the zinc negative electrode after cycling 5 times under the current density of 10 mA / cm 2 and the fixed capacity of 2 mAh / cm 2 for the symmetric battery assembled with blank electrolyte 1. It can be observed from Figure 1 that there are many large flaky and disordered dendrites.

[0028] As Figure 2 shown is the surface of the zinc negative electrode of the symmetric battery assembled with target electrolyte 2 after cycling 5 times under the same conditions. It can be observed from Figure 2 that the electrode surface is flat and smooth, and no dendrites are formed.

[0029] Example 2

[0030] Blank electrolyte 1:

[0031] The electrolyte is composed of a soluble zinc salt and deionized water. The zinc salt is zinc sulfate (ZnSO4 ) with zinc sulfate (ZnSO 4 ) at a concentration of 1 mol / L, and the balance being water, to obtain blank electrolyte 1.

[0032] Target electrolyte 3:

[0033] The electrolyte consists of a soluble zinc salt, 5-azacytidine and deionized water. The zinc salt is zinc sulfate (ZnSO 4 ), where the concentration of zinc sulfate (ZnSO 4 ) is 1 mol / L, the concentration of 5-azacytidine is 0.2 g / L, and the balance is water, to obtain target electrolyte 3.

[0034] The active material of the zinc-ion battery cathode is prepared by the following method:

[0035] (1) Disperse 1 g of commercial V 2 O 5 powder in 15 mL of 2 mol / L NaCl solution, and stir vigorously at room temperature for 72 h. Centrifuge and dry.

[0036] (2) Grind the dried material into powder, mix it evenly with conductive carbon black and polyvinylidene fluoride in a ratio of 7:2:1, prepare a slurry and coat it on a titanium foil with a thickness of 0.02 mm, and dry at 60 °C for 10 hours to obtain the zinc-ion battery cathode.

[0037] The zinc-ion battery of this example is assembled in the order of negative electrode case, shrapnel, gasket, negative electrode material, separator, and positive electrode material. The negative electrode material is a metal zinc sheet, and the separator is glass fiber. The button battery is assembled in air.

[0038] The electrochemical test of the zinc-ion battery of this example is carried out on a NEWARE test system, and the test temperature is kept constant at 25 °C, and the voltage range is set to 0.2 - 1.6 V.

[0039] As Figure 4 shown, the full battery assembled with blank electrolyte 1 and target electrolyte 3 is charged and discharged at a current density of 1000 mA / g. Their respective electrochemical performances are as Figure 4 shown. After 500 cycles, the capacity retention rate of the full battery using target electrolyte 3 is 45.8%, while the full battery using blank electrolyte 1 decays very rapidly under the same conditions, and the capacity retention rate is only 25.3% after 500 cycles. It can be seen that the electrolyte of the present invention can effectively inhibit the growth of zinc negative electrode dendrites, thereby improving the cycle life of the zinc-ion battery.

[0040] As can be seen from the above embodiments, the preparation steps of the method of the present invention are simple, the raw materials are inexpensive, and it is of great significance for improving the cycle stability, reversible performance and large-scale industrial production of aqueous zinc ion batteries.

[0041] The above are only several embodiments of the present invention, and do not impose any form of limitation on the present invention. Those skilled in the art should understand that the above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. An electrolyte capable of protecting zinc ion battery electrodes, characterized in that: The electrolyte contains 5-azacytidine as an additive.

2. An electrolyte capable of protecting zinc ion battery electrodes, characterized in that: The invention comprises soluble zinc salt, 5-azacytidine and deionized water. The concentration of the soluble zinc salt is 0.1-5 mol / L, and the concentration of the 5-azacytidine is 0.1-5 g / L.

3. The soluble zinc salt according to claim 2, characterized in that The soluble zinc salt is one or more of zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc fluoride, zinc hexafluoride, and zinc trifluoromethanesulfonate.

4. The zinc ion battery according to claim 2, characterized in that It comprises a positive electrode, a negative electrode, a battery separator, and the electrolyte for protecting the zinc ion battery electrode according to claim 1 or 2.

5. The positive electrode according to claim 4, characterized in that The positive electrode is composed of an active material, a conductive agent and a binder.

6. The negative electrode according to claim 4, characterized in that The negative electrode is a zinc sheet, zinc powder, electroplated zinc, foamed zinc or a single zinc material.

7. The battery separator according to claim 4, characterized in that: The battery separator is a glass fiber separator.

8. The active substance according to claim 5, characterized in that The active material is a manganese-based material, a vanadium-based material or a Prussian blue compound.

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