Battery electrolyte and application thereof in zinc ion battery

Abstract

The invention discloses a battery electrolyte and application thereof in a zinc ion battery. When the battery electrolyte is used for the zinc ion battery, the stability of a negative electrode of the zinc ion battery can be greatly improved, corrosion can be slowed down, zinc ions can be induced to be uniformly deposited, the cycle life of the zinc ion battery is greatly prolonged, and the battery electrolyte has great significance in promoting the application of the zinc ion battery in the field of large-scale energy storage.

Description

Technical Field

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

[0002] With the rapid development of the global economy, serious problems such as fossil fuel shortage and worsening environmental pollution have become increasingly prominent. Vigorously developing green energy storage systems to replace or partially replace traditional fossil fuels has become the current research mainstream. Metal ion batteries, such as (lithium, sodium, zinc, magnesium, calcium and aluminum), have received widespread attention in the field of electrochemical storage systems. In particular, lithium-ion batteries are widely used as portable energy storage devices in the market due to their high energy density, light weight, negligible memory effect and long cycle life. However, lithium-ion batteries are high in cost and have safety issues caused by thermal runaway of organic electrolytes. In contrast, aqueous zinc-ion batteries are regarded as a promising large-scale energy storage technology due to their inherent safety and the unique advantages of zinc metal anodes. Among them, the unique advantages include high theoretical capacity (820mAh g -1 ) and low redox potential (-0.76 V vs. SHE). Unfortunately, commercial applications are hampered by corrosion, hydrogen evolution reaction, interfacial parasitic reactions, and dendrite growth of the Zn anode during the zinc plating / stripping process, resulting in low utilization, low Coulombic efficiency, and short cycle life. Therefore, developing effective strategies to address these issues is crucial for the practical application of aqueous Zn-ion batteries.

[0003] In order to solve the above problems of zinc metal, researchers have done a lot of work at this stage, including interface modification, electrolyte optimization and diaphragm modification. Among these options, electrolyte optimization is the simplest and most effective method. Therefore, studying a preparation process of zinc ion battery electrolyte is of great significance for its practical application. Summary of the invention

[0004] The object of the present invention is to provide a battery electrolyte containing an additive, which, when used in a zinc ion battery, can slow down corrosion and induce uniform deposition of zinc ions, and the assembled zinc ion battery has excellent cycle life, long cycle stability and specific capacity.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A battery electrolyte comprising a zinc salt or a hydrate thereof, an additive and a solvent;

[0007] The additive is one or a combination of at least two of 2-acrylamide-2-methylpropane sulfonic acid, sodium dodecylbenzene sulfonate, sodium lignin sulfonate or sodium dodecyl sulfate.

[0008] According to an embodiment of the present invention, in the electrolyte, the mass fraction of the additive in the electrolyte is 0.01-10 wt%, for example, 0.1-5 wt%, such as 0.5%, 1% or 2%.

[0009] According to an embodiment of the present invention, in the electrolyte, the concentration of the zinc salt or its hydrate is 0.1-5 mol / L, such as 0.5-3 mol / L, such as 2 mol / L.

[0010] According to an embodiment of the present invention, the zinc salt or its hydrate includes any one of zinc acetate, zinc sulfate, zinc sulfate heptahydrate, zinc chloride, zinc tetrafluoroborate, zinc perchlorate, zinc trifluoromethanesulfonate or zinc nitrate, or a combination of at least two thereof; preferably zinc sulfate or zinc sulfate heptahydrate.

[0011] The present invention adds additives to the battery electrolyte, and the additives in the system can be preferentially adsorbed on the surface of the zinc negative electrode to hinder the two-dimensional diffusion of zinc ions, thereby inhibiting the growth of dendrites and extending the battery cycle life.

[0012] According to an embodiment of the present invention, the solvent includes one or a combination of at least two of deionized water, ethylene carbonate, acetonitrile, trimethyl phosphate, triethyl phosphate, methyl carbonate propionate, ethyl propionate, ethyl acetate, ethyl methyl carbonate, methyl formate, propylene carbonate, methyl acetate, triethylene glycol dimethyl ether or dimethyl sulfoxide; preferably deionized water.

[0013] The present invention also provides a method for preparing the battery electrolyte, comprising the following steps: mixing a zinc salt or a hydrate thereof, an additive and a solvent.

[0014] The present invention also provides application of the battery electrolyte in a zinc ion battery.

[0015] According to an embodiment of the present invention, the zinc ion battery is an aqueous zinc ion battery.

[0016] According to an embodiment of the present invention, the aqueous zinc ion battery further includes a positive electrode sheet, a negative electrode sheet and a separator.

[0017] According to an embodiment of the present invention, the aqueous zinc ion battery is a zinc symmetric battery, a zinc-copper battery or a zinc ion full battery.

[0018] According to an embodiment of the present invention, the zinc symmetrical battery comprises a positive electrode shell, a negative electrode shell, two symmetrical zinc foils, a separator, nickel foam and the battery electrolyte as described above.

[0019] According to an embodiment of the present invention, the zinc-copper battery includes a positive electrode shell, a negative electrode shell, a zinc foil, a copper foil, a separator, a nickel foam and the battery electrolyte as described above.

[0020] According to an embodiment of the present invention, the zinc ion full battery includes a positive electrode shell, a negative electrode shell, a positive electrode, a zinc foil, a separator, nickel foam and the battery electrolyte as described above.

[0021] According to an embodiment of the present invention, the separator is one of a PE separator, a PP separator, a PP / PE separator, a glass fiber separator and a cellulose separator, preferably a glass fiber separator.

[0022] According to an embodiment of the present invention, the positive electrode shell includes a positive electrode material, a conductive agent, a binder and a current collector. The positive electrode material includes a manganese-based or vanadium-based material embedded; preferably MnO2, V2O5. The conductive agent includes any one or a combination of at least two of conductive carbon black, acetylene black or Ketjen black; preferably conductive carbon black. The binder is polytetrafluoroethylene. The current collector includes stainless steel foil, titanium foil or carbon cloth.

[0023] According to an embodiment of the present invention, the positive electrode is manganese dioxide, the separator is a glass fiber membrane, and the negative electrode is metallic zinc.

[0024] According to an embodiment of the present invention, the preparation method of the aqueous zinc ion battery comprises the following steps:

[0025] S1. Preparation of manganese dioxide positive electrode: manganese dioxide, acetylene black and polyvinylidene fluoride are mixed in a certain mass ratio, N-methylpyrrolidone is added to form a slurry, and then the slurry is scraped to form an electrode sheet, which is pressed on a cut stainless steel mesh or titanium foil to form an electrode sheet, and then dried in a vacuum for 12 to 24 hours to obtain a manganese dioxide positive electrode sheet;

[0026] S2. Preparation of zinc negative electrode: cutting zinc foil into suitable size, then grinding the zinc foil with sandpaper of different sizes and cleaning the zinc foil with ethanol to obtain the negative electrode sheet;

[0027] S3. Assembly of zinc ion batteries: Assemble aqueous zinc ion batteries in CR2032 button cell shells. The corresponding assembly order is positive electrode shell, positive electrode plate, glass fiber diaphragm, electrolyte, zinc negative electrode plate, nickel foam and negative electrode shell; for zinc symmetrical batteries, the electrodes on both sides of the diaphragm are zinc foil; place the assembled battery on a button cell sealing machine for pressure sealing.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention provides a battery electrolyte, which, when used in a zinc ion battery (particularly an aqueous zinc ion battery), can greatly improve the stability of the negative electrode of the zinc ion battery, slow down corrosion and induce uniform deposition of zinc ions, greatly prolonging the cycle life of the zinc ion battery, and is of great significance for promoting its application in the field of large-scale energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a test chart of the corrosion performance of the electrolyte in Example 1 of the present invention.

[0031] Figure 2 It is a test chart of the corrosion performance of the electrolyte in Comparative Example 1 of the present invention.

[0032] Figure 3 It is a long cycle performance test diagram of the zinc symmetrical battery assembled with the electrolyte prepared in Example 1 of the present invention and Comparative Example 1.

[0033] Figure 4 It is a linear cyclic voltammetry curve of the full battery assembled with the electrolyte prepared in Example 1 of the present invention and Comparative Example 1.

[0034] Figure 5 It is a first cycle charge and discharge curve diagram of a full battery assembled with the electrolyte prepared in Example 1 of the present invention and Comparative Example 1.

[0035] Figure 6 The zinc symmetric battery containing different additives prepared in Example 4 was -2 Current density and 1mAh cm -2 Long cycle performance test under deposition capacity test conditions. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described in detail below through specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0037] Example 1

[0038] A zinc sulfate electrolyte containing 2-acrylamide-2-methylpropanesulfonic acid is used to protect the negative electrode of a zinc ion battery, and the preparation method thereof comprises the following steps:

[0039] 5.751 g of zinc sulfate heptahydrate was added to deionized water to prepare a 10 ml solution, and then ultrasonic dispersion was performed at room temperature to accelerate dissolution to obtain a 2 mol / L zinc sulfate solution. 50 mg of 2-acrylamide-2-methylpropanesulfonic acid was added to the 2 mol / L zinc sulfate solution, and ultrasonic dispersion was performed to accelerate dissolution to obtain a 2 mol / L zinc sulfate electrolyte containing 0.5 wt% of 2-acrylamide-2-methylpropanesulfonic acid.

[0040] The assembly of aqueous zinc-ion batteries follows the following assembly order: positive electrode shell, positive electrode material, separator, electrolyte, negative electrode and negative electrode shell. For zinc symmetric batteries, the electrodes on both sides of the separator are zinc foil; for Zn / / MnO2 batteries, the positive electrode material is MnO2, the negative electrode is zinc foil, and the electrolyte of the battery is 150μL.

[0041] Example 2

[0042] Compared with Example 1, the difference is that the added mass of 2-acrylamide-2-methylpropanesulfonic acid is 100 mg, and a 2 mol / L zinc sulfate electrolyte containing 1 wt % of 2-acrylamide-2-methylpropanesulfonic acid is prepared.

[0043] Example 3

[0044] Compared with Example 1, the difference is that the added mass of 2-acrylamide-2-methylpropanesulfonic acid is 200 mg, and a 2 mol / L zinc sulfate electrolyte containing 2 wt % of 2-acrylamide-2-methylpropanesulfonic acid is prepared.

[0045] Comparative Example 1

[0046] Compared with Example 1, the difference is that 2-acrylamide-2-methylpropanesulfonic acid is not added, and a 2 mol / L zinc sulfate electrolyte is prepared.

[0047] Figure 1 This is an SEM picture of the zinc foil immersed in the electrolyte prepared in Example 1 for 3 days. It can be seen that the surface of the zinc foil after immersion is flat and smooth and no by-products are generated, indicating that the zinc foil has good chemical stability in the electrolyte of Example 1 and is not easily corroded.

[0048] Figure 2 This is a SEM image of zinc foil immersed in the electrolyte prepared in Comparative Example 1 for 3 days. After immersion for 3 days, irregular dendrites and byproducts were observed on the surface of the zinc foil. Figure 1 and Figure 2 It can be seen that by adding 2-acrylamide-2-methylpropanesulfonic acid additive to the electrolyte, the corrosion of the zinc sheet in the electrolyte is effectively inhibited, the zinc sheet exhibits good chemical stability, shows a uniform zinc deposition morphology, and can effectively improve the cycle life of the battery.

[0049] Figure 3 The zinc symmetric cells were assembled with the electrolytes prepared in Example 1 and Comparative Example 1 at a current density of 1 mA cm -2 and an area capacity density of 1 mAh cm -2 Long cycle performance test diagram under 1mA cm -2 Current density and 1 mA cm -2Under the test conditions of deposition capacity, the zinc symmetric battery shows a stable voltage curve and can achieve an ultra-long cycle life of 3000h. -2 Current density and 1 mA cm -2 Under the test conditions of deposition capacity, the cycle life of the zinc symmetric battery is less than 330h. This further illustrates that the 2-acrylamide-2-methylpropanesulfonic acid additive can effectively extend the cycle life of aqueous zinc ion batteries.

[0050] Figure 4 The aqueous zinc ion batteries prepared in Example 1 and Comparative Example 1 were subjected to linear cyclic voltammetry tests. The results of Example 1 and Comparative Example 1 showed that both Example 1 and Comparative Example 1 showed obvious redox peaks, while the battery using 2-acrylamide-2-methylpropanesulfonic acid additive had a smaller redox overpotential. This indicates that 2-acrylamide-2-methylpropanesulfonic acid additive can induce Zn 2+ transmission, which can enhance its dynamics.

[0051] Figure 5 The first charge and discharge curves of the aqueous zinc ion battery prepared in Example 1 and Comparative Example 1 at a current density of 0.1 A / g are shown. It can be clearly observed from the figure that the full battery containing 2-acrylamide-2-methylpropanesulfonic acid has a higher discharge specific capacity.

[0052] Example 4

[0053] Referring to the steps of Example 1, zinc sulfate electrolytes containing the same mass fraction (2wt%) of 2-acrylamide-2-methylpropane sulfonic acid, sodium dodecylbenzene sulfonate, sodium lignin sulfonate or sodium dodecyl sulfate additives were prepared, zinc symmetric batteries were assembled, and their cycle stability was tested.

[0054] Figure 6 The zinc symmetric battery containing different additives prepared in Example 4 was -2 Current density and 1mAh cm -2 Long cycle performance test under the test conditions of deposition capacity. As can be seen from the figure, 2-acrylamide-2-methylpropanesulfonic acid has the longest cycle life and better cycle performance compared with other additives.

[0055] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A battery electrolyte, characterized in that: It includes zinc salt or its hydrate, additives and solvent; The additive is one or a combination of at least two of 2-acrylamide-2-methylpropane sulfonic acid, sodium dodecylbenzene sulfonate, sodium lignin sulfonate or sodium dodecyl sulfate.

2. The electrolyte according to claim 1, characterized in that In the electrolyte, the mass fraction of the additive in the electrolyte is 0.01 to 10 wt %.

3. The battery electrolyte according to claim 1 or 2, characterized in that: In the electrolyte, the concentration of the zinc salt or its hydrate is 0.1 to 5 mol / L.

4. The battery electrolyte according to claim 1 or 2, characterized in that: The zinc salt or its hydrate includes any one or a combination of at least two of zinc acetate, zinc sulfate, zinc sulfate heptahydrate, zinc chloride, zinc tetrafluoroborate, zinc perchlorate, zinc trifluoromethanesulfonate or zinc nitrate.

5. The battery electrolyte according to claim 1 or 2, characterized in that: The solvent includes one or a combination of at least two of deionized water, ethylene carbonate, acetonitrile, trimethyl phosphate, triethyl phosphate, methyl carbonate propionate, ethyl propionate, ethyl acetate, ethyl methyl carbonate, methyl formate, propylene carbonate, methyl acetate, triethylene glycol dimethyl ether or dimethyl sulfoxide.

6. Use of the battery electrolyte according to any one of claims 1 to 5 in a zinc ion battery.

7. The use according to claim 6, characterized in that: The zinc ion battery is an aqueous zinc ion battery.

8. The use according to claim 7, characterized in that: The aqueous zinc ion battery is a zinc symmetrical battery, a zinc-copper battery or a zinc ion full battery.

9. The use according to claim 7 or 8, characterized in that: The aqueous zinc ion battery also includes a positive electrode sheet, a negative electrode sheet and a separator.

10. The use according to claim 9, characterized in that: The diaphragm is one of a PE diaphragm, a PP diaphragm, a PP / PE diaphragm, a glass fiber diaphragm and a cellulose diaphragm.

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