Aqueous zinc ion battery electrolyte

Abstract

The application belongs to the field of secondary batteries, and particularly relates to a zinc ion battery electrolyte. The composition of the electrolyte comprises water, a zinc salt, a formate salt and an amine molecule. The electrolyte of the application can induce uniform zinc deposition and present (0002) crystal face preferred orientation due to the addition of the formate salt and the amine molecule, and inhibit the formation of zinc dendrites. The zinc ion battery prepared by using the electrolyte has uniform and smooth zinc morphology in the charging and discharging cycle process, greatly improves the cycle stability, and has a simple scheme, is easy to industrialize, and has application prospects in the field of energy storage technology.

Description

Technical Field

[0001] This invention belongs to the field of aqueous secondary battery technology, specifically relating to a zinc-ion battery electrolyte. Background Technology

[0002] Developing new energy sources such as hydropower, wind power, and solar power is an important way to solve future energy depletion and global environmental pollution problems. However, these energy sources are easily affected by seasonal and weather factors, resulting in discontinuous and unstable power generation, making grid connection difficult. Consequently, the phenomenon of wasted hydropower, wind power, and solar power is serious, necessitating energy storage technology to address these issues. Electrochemical energy storage technology has developed rapidly, offering advantages such as low investment, high efficiency, and flexible use, and has become a research focus for researchers in recent years. Large-scale energy storage requires meeting the conditions of safety, reliability, and low cost. Among these, aqueous zinc-ion batteries, a type of secondary battery using zinc metal as the negative electrode, manganese dioxide as the positive electrode, and zinc salt aqueous solution as the electrolyte, can well meet these requirements and has recently become a focus of attention, possessing significant research value.

[0003] However, the development of aqueous zinc-ion batteries still has many shortcomings. One key problem is that the zinc anode is prone to dendrite formation during use, leading to accelerated corrosion and short circuits. In recent years, researchers have developed various strategies to address this issue, such as surface coatings, constructing three-dimensional current collectors, electrolyte additives, and epitaxial electrodeposition [EnergyEnviron.Sci., 2020, 13, 3330]. These strategies have effectively slowed down dendrite growth, but they still cannot fully meet the needs of practical applications. Exploring new solutions will have a profound impact on the large-scale application of zinc-ion batteries. Summary of the Invention

[0004] To address the problem of dendrite formation in zinc metal anodes, this invention provides a zinc-ion battery electrolyte that enables uniform zinc deposition and achieves preferred orientation of the (0002) crystal plane, thereby increasing battery cycle performance. Furthermore, the preparation method is simple and inexpensive.

[0005] The technical solution of this invention is as follows:

[0006] On one hand, the present invention provides a zinc-ion battery electrolyte, the electrolyte comprising water, zinc salt, formate and amine molecules; the formate is a water-soluble formate; the amine molecules are cyclohexylamine.

[0007] As a preferred embodiment of the present invention, the zinc salt includes one or more of zinc sulfate, zinc nitrate, zinc chloride, or zinc acetate.

[0008] As a preferred embodiment of the present invention, the water-soluble formate includes one or more of lithium formate, sodium formate, potassium formate, rubidium formate, cesium formate, magnesium formate, calcium formate, or zinc formate.

[0009] As a preferred embodiment of the present invention, the molar concentration of the zinc salt is 0.5–2 mol·L⁻¹. -1 .

[0010] As a preferred embodiment of the present invention, the molar concentration of the formate is 0.2–1 mol·L⁻¹. -1 .

[0011] As a preferred embodiment of the present invention, the concentration of the amine molecules is 0.4–1.4 mol·L⁻¹. -1 .

[0012] On the other hand, the present invention also provides a method for preparing the above-mentioned zinc-ion battery electrolyte, the method comprising the following steps:

[0013] The formate and amine molecules are added to a beaker and dissolved in deionized water. The pH of the solution is adjusted to ~7 by adding dilute acid solution. Finally, zinc salt is added and stirred until completely dissolved to obtain the zinc-ion battery electrolyte.

[0014] In another aspect, the present invention provides an aqueous zinc-ion battery using the above-mentioned zinc-ion battery electrolyte.

[0015] The present invention has the following beneficial effects:

[0016] This invention slows down the desolvation process of zinc and induces zinc crystal plane reconstruction by adding formate and amine that can coordinate with zinc ions, resulting in uniform zinc deposition with a preferred orientation of the (0002) crystal plane. This ensures a smooth morphology during charge-discharge cycles, effectively solves the dendrite problem, and improves the cycle performance of aqueous zinc-ion batteries. The solution is simple, low-cost, and easy to industrialize, making it promising for application in the field of energy storage technology. Attached Figure Description

[0017] Figure 1 The diagram shows the cycle performance of the Zn / / Zn symmetric battery assembled using the electrolyte in Example 1 of this invention.

[0018] Figure 2 This is a scanning electron microscope (SEM) image of the zinc negative electrode after the zinc has been circulated in the electrolyte for 300 hours in Example 1 of this invention.

[0019] Figure 3 The image shows the X-ray diffraction (XRD) pattern of the zinc anode after the electrolyte has been circulated for 300 hours in Example 1 of this invention.

[0020] Figure 4 The diagram shows the cycle performance of a Zn / / MnO2 full cell assembled using the electrolyte in Example 1 of this invention.

[0021] Figure 5The diagram shows the cycle performance of the Zn / / Zn symmetric battery assembled using the electrolyte in Example 2 of this invention.

[0022] Figure 6 The diagram shows the cycle performance of the Zn / / Zn symmetric battery assembled using the electrolyte in Example 3 of this invention.

[0023] Figure 7 The circuit performance diagram shows the Zn / / Zn symmetric cell assembled using the electrolyte in Comparative Example 1.

[0024] Figure 8 The image shows a scanning electron microscope (SEM) image of the zinc anode after the zinc was circulated in the electrolyte in Comparative Example 1 of this invention for 300 hours.

[0025] Figure 9 The graph shows the cycle performance of the Zn / / MnO2 full cell assembled using the electrolyte in Comparative Example 1.

[0026] Figure 10 The circuit performance diagram shows the Zn / / Zn symmetric cell assembled using the electrolyte in Comparative Example 2.

[0027] Figure 11 This is a scanning electron microscope (SEM) image of the zinc anode after the zinc was circulated in the electrolyte in Comparative Example 2 of this invention for 77 hours.

[0028] Figure 12 The circuit performance diagram shows the Zn / / Zn symmetric cell assembled using the electrolyte in Comparative Example 3.

[0029] Figure 13 The image shows a scanning electron microscope (SEM) image of the zinc anode after the zinc was circulated in the electrolyte for 135 hours in Comparative Example 3 of this invention. Detailed Implementation

[0030] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0031] The cycle performance tests of the Zn / / Zn symmetric batteries described in Examples 1-3 and Comparative Examples 1-3 were conducted under the following conditions: the simulated batteries used a CR2032 coin cell system, with the electrolyte being the electrolyte described in Examples 1-3 and Comparative Examples 1-3; both positive and negative electrodes were 50μm zinc foil; and the separator was a glass fiber membrane. Constant current charge-discharge tests were performed at a current of 2mA·cm⁻¹. -2 The capacity is 5mAh·cm -2 .

[0032] Example 1

[0033] An electrolyte for aqueous zinc-ion batteries is prepared through the following experimental steps:

[0034] Dissolve 5 mmol sodium formate and 8 mmol cyclohexylamine in 6 mL of deionized water, adjust the pH to approximately 7 with 1 M dilute sulfuric acid solution, then add 10 mmol zinc sulfate, stir until completely dissolved, and finally bring the volume to 10 mL to obtain a 0.5 M sodium formate + 0.8 M cyclohexylamine + 1 M zinc sulfate solution.

[0035] The cycle performance simulation of the Zn / / MnO2 full cell used a CR2032 coin cell system, with the electrolyte described in this embodiment, zinc foil as the negative electrode, manganese dioxide as the positive electrode, and a glass fiber membrane as the separator. The positive electrode was prepared by mixing active material, acetylene black, and PVDF in a mass ratio of 8:1:1 to form a slurry, which was then coated onto nickel foam and dried in a forced-air drying oven at 80°C for 6–12 hours. The battery was tested using constant current charge-discharge, with a charge-discharge voltage range of 1.0V–1.8V.

[0036] like Figure 1 As shown, the Zn / / Zn symmetric battery assembled using the electrolyte in this embodiment has a cycle life of 490 hours. Figure 4 As shown, the Zn / / MnO2 full cell showed no significant capacity decay after 45 cycles. (From scanning electron microscope (SEM) images...) Figure 2 ) and X-ray diffraction (XRD) pattern ( Figure 3 It can be seen that after the zinc cycle, the (0002) crystal plane exhibits a preferred orientation.

[0037] Example 2

[0038] Dissolve 5 mmol sodium formate and 12 mmol cyclohexylamine in 6 mL of deionized water, adjust the pH to approximately 7 with 1 M dilute sulfuric acid solution, then add 10 mmol zinc sulfate, stir until completely dissolved, and finally bring the volume to 10 mL.

[0039] like Figure 5 As shown, the Zn / / Zn symmetric battery assembled using the electrolyte described in this embodiment has a cycle life of 220 hours.

[0040] Example 3

[0041] Dissolve 2 mmol sodium formate and 10 mmol cyclohexylamine in 6 ml of deionized water, adjust the pH to about 7 with 1 M dilute sulfuric acid solution, then add 10 mmol zinc sulfate, stir until completely dissolved, and finally bring the volume to 10 mL.

[0042] like Figure 6 As shown, the Zn / / Zn symmetric battery assembled using the electrolyte described in this embodiment has a cycle life of 330 hours.

[0043] Comparative Example 1

[0044] Dissolve 10 mmol of zinc sulfate in deionized water to prepare a 1 M zinc sulfate solution.

[0045] The Zn / / MnO2 full-cell cycle performance simulation used a CR2032 coin cell system, with the electrolyte being the one described in this comparative example. The negative electrode was zinc foil, the positive electrode was manganese dioxide, and the separator was a glass fiber membrane. The positive electrode was prepared by mixing active material, acetylene black, and PVDF in a mass ratio of 8:1:1 to form a slurry, which was then coated onto nickel foam and dried in a forced-air drying oven at 80°C for 6–12 hours. The battery was tested using constant current charge-discharge, with a charge-discharge voltage range of 1.0V–1.8V.

[0046] like Figure 7 and Figure 8 As shown, the Zn / / Zn symmetric battery assembled using the electrolyte described in this comparative example has a cycle life of 40 hours, and the SEM image after cycling exhibits an irregular and uneven morphology. Figure 9 As shown, a short circuit occurs in the Zn / / MnO2 full cell after 14 cycles.

[0047] Comparative Example 2

[0048] Dissolve 5 mmol of sodium formate in deionized water, adjust the pH to approximately 7 with 1M dilute sulfuric acid solution, then add 10 mmol of zinc sulfate, stir until completely dissolved, and finally bring the volume to 10 mL to obtain a 0.5M sodium formate + 1M zinc sulfate solution.

[0049] like Figure 10 and Figure 11 As shown, the Zn / / Zn symmetric battery assembled using the electrolyte described in this comparative example has a cycle life of 77 h, and the SEM image after cycling shows an irregular and uneven morphology.

[0050] Comparative Example 3

[0051] Dissolve 8 mmol of cyclohexylamine in deionized water, adjust the pH to approximately 7 with 1 M dilute sulfuric acid solution, then add 10 mmol of zinc sulfate, stir until completely dissolved, and finally bring the volume to 10 mL to obtain a 0.8 M cyclohexylamine + 1 M zinc sulfate solution.

[0052] like Figure 12 and Figure 13 As shown, the Zn / / Zn symmetric battery assembled using the electrolyte described in this comparative example has a cycle life of 135 hours, and the SEM image after cycling shows an irregular and uneven morphology.

Claims

1. An aqueous zinc-ion battery electrolyte, characterized in that, The electrolyte comprises water, zinc salt, formate, and amine molecules; the formate is a water-soluble formate; and the amine molecules are cyclohexylamine. The water-soluble formate includes one or more of lithium formate, sodium formate, potassium formate, rubidium formate, cesium formate, magnesium formate, calcium formate, or zinc formate; The zinc salt includes one or more of zinc sulfate, zinc nitrate, zinc chloride, or zinc acetate; The molar concentration of the zinc salt is 0.5~2 mol·L⁻¹. -1 ; The molar concentration of the formate is 0.2~1 mol·L⁻¹. -1 ; The molar concentration of the amine molecules is 0.4~1.4 mol·L⁻¹ -1 ; The method for preparing the aqueous zinc-ion battery electrolyte includes the following steps: adding the formate and amine molecules into a container, dissolving them with deionized water, adding an acid solution to adjust to neutral, and finally adding the zinc salt and stirring until completely dissolved to obtain the electrolyte.

2. An aqueous zinc-ion battery, characterized in that, The battery includes the aqueous zinc-ion battery electrolyte as described in claim 1.

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