Aqueous zinc ion battery electrolyte

Abstract

The invention discloses an aqueous zinc ion battery electrolyte, and relates to the technical field of new energy batteries. The electrolyte contains a solvent, a zinc salt and lactitol capable of inhibiting growth of zinc dendrites and inhibiting generation of side reactions. According to the invention, the lactitol is added into the zinc salt solution to obtain the electrolyte solution with good conductivity. The polyhydroxy organic molecule lactitol can interact with a zinc anode electrolyte interface to selectively adsorb and adjust Zn < 2 + > deposition, prevent zinc ions from aggregating into dendritic crystals and inhibit zinc dendritic crystal growth. In addition, hydroxyl can participate in reconstruction of a hydrogen bond network, so that the activity of water is reduced, and related side reactions are inhibited. A Zn / / Cu half battery assembled based on the electrolyte has 99.42% coulombic efficiency, and a Zn / / Zn symmetrical battery can stably circulate for more than 1300 hours under the conditions of 1mA cm <-2 > and 1mAh cm <-2 >.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy batteries, and in particular to an aqueous zinc ion battery electrolyte. Background Art

[0002] Energy is the source of power for the survival and development of human society. Since the Industrial Revolution, the over-exploitation and use of traditional fossil energy has also brought about serious environmental and climate problems, which has posed serious challenges to the sustainable development of mankind. Against this background, electrochemical energy storage technology has rapidly become popular due to its good environmental adaptability, low investment and flexible use. Electrochemical energy storage represented by lithium-ion batteries has been widely used in recent years. However, limited lithium resource reserves, harsh assembly conditions, and safety issues such as flammability and explosion caused by flammable organic electrolytes have restricted its further development, so the research and development of new electrochemical energy storage systems is imminent.

[0003] Aqueous zinc-ion batteries refer to secondary batteries that use water as the electrolyte. Compared with lithium-ion batteries, aqueous zinc-ion batteries have the advantages of high safety, environmental friendliness, high ionic conductivity and theoretical specific capacity, and have attracted widespread attention from scientific researchers. However, due to the complex interfacial chemical reactions between the zinc surface and the electrolyte, the zinc anode always encounters serious problems during the long-term reversible plating / stripping process. These include new dendrites, dead zinc, side reactions (corrosion, hydrogen evolution), etc. This results in low coulombic efficiency (CE) and poor cycle stability of the zinc negative electrode during the reversible cycle.

[0004] Currently, many studies only focus on remodeling hydrated Zn 2+ Solvation shells are used to suppress Zn dendrites, while ignoring the electrode-electrolyte interface effect, resulting in unsatisfactory deposition kinetics and shortened lifetime. The challenges faced by these additives currently include mitigating single modification effects, dendrite growth, and side reactions. Therefore, the development of multifunctional additives is of great significance in optimizing electrolytes, regulating electrode-electrolyte interfaces, and Zn 2+ There is a broad prospect in transmission. Summary of the invention

[0005] The present invention provides an aqueous zinc ion battery electrolyte, and optimizes a cost-effective electrolyte by introducing a multifunctional lactitol additive to realize a reversible aqueous zinc ion battery.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An aqueous zinc ion battery electrolyte contains a solvent, a zinc salt and lactitol capable of inhibiting zinc dendrite growth and inhibiting side reactions. The concentration of the lactitol in the electrolyte is 0.01-0.1 mol / L.

[0008] As a preferred technical solution of the present invention, in the aqueous zinc ion battery electrolyte:

[0009] The solvent is deionized water. The zinc salt is selected from one or a combination of two or more of zinc sulfate, zinc chloride, zinc bromide, zinc silicate, zinc carbonate, zinc nitrate, zinc sulfonate, zinc borate, zinc acetate and zinc perchlorate. The concentration of the zinc salt in the electrolyte is 1 to 4 mol / L.

[0010] The method for preparing the aqueous zinc ion battery electrolyte is specifically as follows: zinc salt and lactitol are mixed and dissolved in a solvent, and stirred until the solution is clear.

[0011] The present invention also provides an aqueous zinc ion battery made by using the electrolyte, which is specifically assembled from the aqueous zinc ion battery electrolyte, a positive electrode material, a zinc sheet, a gasket and a spring.

[0012] The present invention adjusts the electrode / electrolyte interface by adding lactitol to the electrolyte, thereby significantly inhibiting dendrites and byproducts and improving battery performance. Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1) The present invention provides an aqueous zinc ion battery electrolyte, wherein lactitol is added to a zinc salt solution to obtain an electrolyte solution with good conductivity. The polyhydroxy organic molecule lactitol can interact with the zinc anode electrolyte interface to selectively adsorb and regulate Zn 2+ The deposition of Zn ions prevents the aggregation of zinc ions into dendrites and inhibits the growth of zinc dendrites. In addition, hydroxyl groups can participate in the reconstruction of the hydrogen bond network, thereby reducing the activity of water and inhibiting related side reactions. The Zn / / Cu half-cell assembled based on this electrolyte has a Coulombic efficiency of 99.42%, and the Zn / / Zn symmetric cell has a Coulombic efficiency of 1 mA cm -2 and 1mAh cm -2 Under the given conditions, it can circulate stably for more than 1300h.

[0014] 2) In the present invention, a small amount of low-cost additives are added to a low-concentration salt solution to obtain an electrolyte, and the electrolyte is applied to a zinc ion energy storage battery. The synthesis steps are simple and no special treatment is required. Compared with similar technologies, the zinc ion battery provided by the present invention has good cycle stability and reversibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 For (a) 20 mA cm -2 (b) 30mAcm -2 SEM morphology evolution diagram of zinc sheet deposited in aqueous zinc ion battery electrolyte prepared in Example 1 under current density.

[0016] Figure 2To assemble a Zn / / Cu half-cell using the aqueous zinc ion battery electrolyte prepared in Example 1 at a current density of 5 mA cm -2 、Surface capacity is 5mAhcm -2 The coulombic efficiency under .

[0017] Figure 3 To assemble a Zn / / Zn symmetrical battery using the aqueous zinc ion battery electrolyte prepared in Example 2 at a current density of 1 mA cm -2 , surface capacity is 1 mAh cm -2 The cycle performance diagram below.

[0018] Figure 4 To assemble a Zn / / Cu half-cell using the aqueous zinc ion battery electrolyte prepared in Example 2 at a current density of 1 mA cm -2 , surface capacity is 1mAhcm -2 The coulombic efficiency under .

[0019] Figure 5 To assemble a Zn / / Zn symmetrical cell using the aqueous zinc ion battery electrolyte prepared in Example 3 at a current density of 1 mA cm -2 , surface capacity is 1 mAh cm -2 The cycle performance diagram below.

[0020] Figure 6 To assemble a Zn / / Zn symmetrical battery using the aqueous zinc ion battery electrolyte prepared in Example 3 at a current density of 1-15 mA cm -2 , surface capacity is 1 mAh cm -2 Lower rate cycling performance diagram. DETAILED DESCRIPTION

[0021] Example 1

[0022] This embodiment provides a method for preparing an aqueous zinc ion battery electrolyte capable of inhibiting dendrites and byproducts:

[0023] Weigh appropriate amounts of ZnSO4 and lactitol, mix and dissolve them in deionized water, make up to 10 mL, stir the solution until it becomes clear, and prepare 1M ZnSO4+0.01M lactitol electrolyte #1.

[0024] Example 2

[0025] This embodiment provides a method for preparing an aqueous zinc ion battery electrolyte capable of inhibiting dendrites and byproducts:

[0026] Weigh appropriate amounts of ZnSO4 and lactitol, mix and dissolve them in deionized water, make up to 10 mL, stir the solution until it becomes clear, and prepare 1M ZnSO4+0.05M lactitol electrolyte #2.

[0027] Example 3

[0028] This embodiment provides a method for preparing an aqueous zinc ion battery electrolyte capable of inhibiting dendrites and byproducts:

[0029] Weigh appropriate amounts of ZnSO4 and lactitol, mix and dissolve them in deionized water, make up to 10 mL, stir the solution until it becomes clear, and prepare 1M ZnSO4+0.1M lactitol electrolyte #3.

[0030] Example 4

[0031] Zinc ion battery performance test

[0032] First, the electrolytes prepared in Examples 1, 2, and 3 were used to prepare Zn / / Cu half-cells and Zn / / Zn symmetrical cells according to the following method:

[0033] The preparation method of Zn / / Cu half-cell is as follows: select appropriate electrode materials to ensure the quality and purity of the materials. Before assembling the battery, the materials need to be cleaned and dried to remove surface impurities and moisture. Select positive electrode Cu sheet and negative electrode Zn sheet with a diameter of 15 mm, and select glass fiber GF / D for the separator. Then assemble the positive electrode battery shell, positive electrode sheet, separator, electrolyte, negative electrode sheet, gasket, shrapnel and negative electrode battery shell together in sequence to obtain Zn / / Cu half-cell.

[0034] The preparation method of the Zn / / Zn symmetrical battery is as follows: select suitable electrode materials to ensure the quality and purity of the materials. Before assembling the battery, the materials need to be cleaned and dried to remove surface impurities and moisture. Select positive and negative Zn sheets with a diameter of 15 mm, and select glass fiber GF / D for the separator. The positive battery shell, positive sheet, separator, electrolyte, negative sheet, gasket, shrapnel and negative battery shell are assembled together in sequence to obtain a Zn / / Zn symmetrical battery.

[0035] Next, the zinc sheet was deposited in the aqueous zinc ion battery electrolyte #1 prepared in Example 1. The specific test steps are as follows: -2 and 10mA cm -2 At the current density, both the positive and negative electrodes are zinc sheets. After charging for 1 hour, the positive zinc sheet is subjected to SEM test. The test results are as follows: Figure 1 As shown. Figure 1 It can be seen that the surface of the zinc sheet presents a flat stacking form, indicating a uniform deposition morphology.

[0036] The Zn / / Cu half-cell assembled with aqueous zinc ion battery electrolyte #1 prepared in Example 1 was subjected to a zinc deposition / stripping reversibility test. The specific test steps were as follows: 5 mA cm-2 The charge and discharge current is 60 minutes, the discharge time is 60 minutes, the charging cut-off voltage is 0.3V, and the coulomb efficiency is recorded as the number of cycles changes. The test results are as follows Figure 2 As shown. Figure 2 It can be seen that after 280 cycles, the average Coulomb efficiency is 99.42%, confirming the good reversibility of zinc stripping / deposition.

[0037] The Zn / / Zn symmetrical battery assembled with aqueous zinc ion battery electrolyte #2 prepared in Example 2 was tested for battery performance. The specific test steps were as follows: -2 、Surface capacity 1mAh cm -2 Record the change of voltage with the number of cycles. The test results are as follows: Figure 3 As shown. Figure 3 It can be seen that at 1 mA cm -2 The battery has good cycling stability at high current density.

[0038] The Zn / / Cu half-cell assembled with aqueous zinc ion battery electrolyte #2 prepared in Example 2 was subjected to a zinc deposition / stripping reversibility test. The specific test steps were as follows: 1 mA cm was applied to the Zn / / Cu half-cell. -2 The charge and discharge current is 60 minutes, the discharge time is 60 minutes, the charging cut-off voltage is 0.3V, and the coulomb efficiency is recorded as the number of cycles changes. The test results are as follows Figure 4 As shown. Figure 4 It can be seen that after 520 cycles, the average Coulomb efficiency is 99.32%, confirming the good reversibility of zinc stripping / deposition.

[0039] The Zn / / Zn symmetrical battery assembled with aqueous zinc ion battery electrolyte #3 prepared in Example 3 was tested for battery performance. The specific test steps are as follows: -2 、Surface capacity 1mAh cm -2 Record the change of voltage with the number of cycles. The test results are as follows: Figure 5 As shown. Figure 5 It can be seen that at 1 mA cm -2 The battery can cycle stably for more than 1300 hours at the current density, and the battery has good stability.

[0040] The rate performance test was conducted on the Zn / / Zn symmetrical battery assembled with aqueous zinc ion battery electrolyte #3 prepared in Example 3. The specific test steps were as follows: -2 、Surface capacity 1mAh cm -2 The voltage of the zinc symmetric battery is recorded as the number of cycles changes. The test results are as follows: Figure 6 As shown. Figure 6It can be seen that the symmetrical battery can maintain stable cycling at all current densities.

[0041] The above test results confirm that the aqueous zinc ion electrolyte containing lactitol additive prepared by the present invention can effectively improve the cycle stability of rechargeable aqueous zinc ion batteries and has great application prospects in energy storage.

[0042] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. An aqueous zinc ion battery electrolyte, comprising a solvent and a zinc salt, characterized in that: Lactitol is also added into the electrolyte to inhibit the growth of zinc dendrites and the occurrence of side reactions. The concentration of the lactitol in the electrolyte is 0.01-0.1 mol / L.

2. The aqueous zinc ion battery electrolyte according to claim 1, wherein The solvent is deionized water.

3. The aqueous zinc ion battery electrolyte according to claim 1, wherein The zinc salt is selected from one or a combination of two or more of zinc sulfate, zinc chloride, zinc bromide, zinc silicate, zinc carbonate, zinc nitrate, zinc sulfonate, zinc borate, zinc acetate and zinc perchlorate.

4. The aqueous zinc ion battery electrolyte according to claim 1, characterized in that The concentration of zinc salt in the electrolyte is 1-4 mol / L.

5. The method for preparing an aqueous zinc ion battery electrolyte according to any one of claims 1 to 4, characterized in that: The preparation method is prepared by mixing and dissolving zinc salt and lactitol in a solvent and stirring until the solution is clear.

6. An aqueous zinc ion battery prepared using the electrolyte according to any one of claims 1 to 4, characterized in that: It is assembled from aqueous zinc-ion battery electrolyte, positive electrode material, zinc sheet, gasket and shrapnel.

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