Salt-in-water electrolyte for aqueous multi-ion battery as well as preparation method and application of salt-in-water electrolyte

Abstract

The invention discloses a salt-in-water electrolyte for an aqueous multi-ion battery and a preparation method and application of the salt-in-water electrolyte, electrolyte is added into water until the electrolyte cannot be dissolved again, and supernate, namely the salt-in-water electrolyte, is taken out; the water-based multi-ion battery takes a molybdenum trioxide nanotube material as a negative electrode, PBA or graphite as a positive electrode and salt-coated water electrolyte as electrolyte. According to the invention, the stability is improved by reducing the water activity of the electrolyte, and meanwhile, more carriers and fewer water molecules occupy reaction active sites of an electrode material, so that the battery capacity is improved. The aqueous multi-ion battery based on reduction of the water activity of the electrolyte has the advantages of high capacity, safety, no toxicity, good stability and the like, and a new thought is provided for preparation of the high-performance aqueous multi-ion battery.

Description

Technical Field

[0001] This invention belongs to the field of battery research, specifically relating to a salt-coated water electrolyte for aqueous multi-ion batteries, its preparation method, and its application. Background Technology

[0002] With the continuous growth of global energy demand and the increasing severity of environmental pollution, developing safe, environmentally friendly, and efficient large-scale energy storage technologies has become a major challenge facing society today. Intermittent renewable energy sources such as solar and wind power have attracted widespread attention from researchers due to their safety and environmental advantages. However, the large-scale harvesting of intermittent renewable energy requires efficient energy storage systems to store, distribute, and utilize electricity. Therefore, the demand for energy conversion and storage is also increasing, making optimized energy management and large-scale storage crucial.

[0003] Aqueous batteries, which use aqueous solutions as electrolytes, offer superior safety and environmental friendliness, demonstrating a strong competitive advantage over traditional lithium-ion batteries. Traditional dilute solutions typically involve the co-intercalation of metal ions and water into materials. During this process, some water is inevitably introduced, and hydrogen evolution side reactions can occur, limiting the voltage window and resulting in lower electrode material capacity. Therefore, developing an electrolyte that enables aqueous electrode materials to achieve high capacity is of great significance. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing technologies, such as the high activity of water in the electrolyte leading to easy hydrogen evolution reaction, poor stability, and low capacity of electrode materials. Its purpose is to provide a salt-coated electrolyte for aqueous multi-ion batteries, its preparation method, and its application.

[0005] This invention is achieved through the following technical solution: A method for preparing a salt-coated water electrolyte for aqueous multi-ion batteries, specifically: adding an electrolyte to water until the electrolyte can no longer dissolve, and taking out the supernatant, which is the salt-coated water electrolyte.

[0006] In the above technical solution, the electrolyte is at least one of LiTFSI, LiCl, LiNO3, NaOTf, NaNO3, NaClO4, KOTf, KOAc, KFSI or ZnCl2.

[0007] In the above technical solution, the salt-coated water electrolyte is a saturated solution.

[0008] A salt-coated electrolyte for use in aqueous multi-ion batteries is prepared by the aforementioned method.

[0009] An application of the aforementioned method for preparing a salt-encapsulated water electrolyte in an aqueous multi-ion battery, wherein the negative electrode of the aqueous multi-ion battery is a molybdenum trioxide nanotube material, and the positive electrode is PBA or graphite.

[0010] In the above technical solution, the preparation method of the negative electrode is as follows: using a molybdenum-tantalum alloy as the anode and a platinum sheet as the cathode, and maintaining an electric current of 50 V for 1-2 h with the electrolyte, the molybdenum-tantalum alloy is taken out and the surface electrolyte is washed off with ethanol, and then heat-treated in an air atmosphere at 500 °C for 2 h to obtain molybdenum trioxide nanotube material, which is the negative electrode of the aqueous multi-ion battery.

[0011] In the above technical solution, the solvent of the electrolyte is a mixture of glycerol and water in a volume ratio of 9:1; the electrolyte is ammonium sulfate and ammonium fluoride; the concentration of ammonium sulfate in the electrolyte is 0.4 M, and the concentration of ammonium fluoride is 0.1 M.

[0012] The beneficial effects of this invention are: This invention provides a salt-coated aqueous electrolyte for aqueous multi-ion batteries, its preparation method, and its application. By reducing the water activity of the electrolyte, bare ions are individually embedded in the material, improving stability. This allows more charge carriers and fewer water molecules to occupy the reactive sites of the electrode material, thereby increasing battery capacity. This invention has broad feasibility and is applicable to various anode materials, providing conditions for subsequent large-scale preparation and commercial applications. It also has significant application value in ion storage research. Attached Figure Description

[0013] Figure 1 The CV test curves of a conventional 1 M LiCl salt solution and the LiCl electrolyte prepared in Example 1 of this invention at low scan rates are shown. Figure 2 This is a comparison of the LSV test curves of a conventional 1 M LiCl salt solution and the LiCl electrolyte prepared in Example 1 of this invention; Figure 3 This is a comparison chart of the long-cycle performance of a conventional 1 M LiCl salt solution and the LiCl electrolyte prepared in Example 1 of this invention at a current density of 5 A / g.

[0014] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0015] 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 below with reference to the accompanying drawings and specific embodiments.

[0016] Example A method for preparing an aqueous lithium-ion battery based on a LiCl salt-encapsulated water electrolyte, specifically comprising: LiCl was added to water until it could no longer dissolve. The supernatant was taken out as the electrolyte, which was a LiCl salt-encapsulated aqueous solution. The concentration of LiCl was measured to be 20 M.

[0017] A slurry was prepared by mixing molybdenum trioxide nanotube array material with a conductive agent (Super P) and a binder (such as PVDF) at a mass ratio of 8:1:1 and adding N-methylpyrrolidone (NMP) to form a paste. This paste was then uniformly coated onto a current collector as a negative electrode material. This was then compared with PBA (K) prepared using the same method. 0.5 Ni 0.5 An aqueous lithium-ion full battery is composed of Fe(CN)6 cathode material and LiCl salt-encapsulated water electrolyte.

[0018] The aqueous lithium-ion battery of Example 1 was tested and characterized, while the electrolyte of Example 1 was replaced with a 1M LiCl dilute solution as a comparative example for simultaneous testing. I. CV Testing Figure 1 This is a comparison of the CV test curves of the LiCl electrolyte prepared according to Example 1 and a conventional dilute 1 M LiCl solution at a scan rate of 2 mV / s. From... Figure 1 It can be seen that Li + The intercalated electrode materials all have only one pair of redox peaks, and the specific capacity of the intercalated electrode materials can be obtained by the area of ​​the CV curve. It was found that the LiCl electrolyte prepared according to Example 1 has a higher specific capacity.

[0019] II. LSV Testing Figure 2 This is a comparison of the LSV test curves of stainless steel mesh in the LiCl electrolyte prepared according to Example 1 and a conventional 1 M LiCl dilute solution. From... Figure 2 It can be seen that the voltage window is significantly increased in the electrolyte prepared in Example 1.

[0020] III. Long-cycle performance test Figure 3 To react the LiCl electrolyte prepared according to Example 1 with a conventional dilute 1 M LiCl solution at 5 A g –1 Comparison of long-cycle performance at current densities. From Figure 3 It can be seen that, based on the electrolyte prepared in Example 1, the specific capacity is 3 times that of a conventional dilute 1 M LiCl solution, and the stability and coulombic efficiency are significantly improved, with the coulombic efficiency approaching 95%.

[0021] Example Based on Example 1, the only difference between this example and Example 1 is that the electrolyte is a KOTf salt-encapsulated aqueous solution. KOTf is added to water until it can no longer dissolve, the supernatant is taken out, and the solution concentration is measured to be 21 M.

[0022] Example Based on Example 1, the only difference between this example and Example 1 is that the electrolyte is a NaClO4 salt-encapsulated aqueous solution. NaClO4 is added to water until it can no longer dissolve, the supernatant is taken out, and the solution concentration is measured to be 17 M.

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0024] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a salt-coated water electrolyte for aqueous multi-ion batteries, characterized in that: Specifically, the electrolyte is added to water until it can no longer dissolve, and the supernatant is taken out, which is the salt-encapsulated electrolyte. The electrolyte is at least one of LiTFSI, LiCl, LiNO3, NaOTf, NaNO3, NaClO4, KOTf, KOAc, KFSI, or ZnCl2.

2. The method for preparing the salt-coated water electrolyte for aqueous multi-ion batteries according to claim 1, characterized in that: The salt-coated water electrolyte is a saturated solution.

3. A salt-coated electrolyte for aqueous multi-ion batteries, characterized in that: Prepared by the method described in claim 1 or 2.

4. The application of the salt-coated water electrolyte prepared by the method of claim 1 or 2 in an aqueous multi-ion battery, characterized in that: The negative electrode of the aqueous multi-ion battery is molybdenum trioxide nanotube material, and the positive electrode is PBA or graphite.

5. The application of the salt-coated water electrolyte according to claim 4 in an aqueous multi-ion battery, characterized in that: The negative electrode is prepared as follows: using a molybdenum-tantalum alloy as the anode and a platinum sheet as the cathode, and maintaining an electrolytic voltage of 50 V for 1 to 2 hours, the molybdenum-tantalum alloy is removed, the surface electrolyte is washed off with ethanol, and then heat-treated in an air atmosphere at 500 °C for 2 hours to obtain molybdenum trioxide nanotube material, which is the negative electrode of the aqueous multi-ion battery.

6. The application of the salt-coated water electrolyte according to claim 5 in an aqueous multi-ion battery, characterized in that: The electrolyte is a solvent composed of glycerol and water in a volume ratio of 9:1; the electrolyte is ammonium sulfate and ammonium fluoride; the concentration of ammonium sulfate in the electrolyte is 0.4 M and the concentration of ammonium fluoride is 0.1 M.

Images