Zinc metal negative electrode with double-layer protective film and preparation method and application thereof

Abstract

The application discloses a zinc metal negative electrode with double-layer protective films and a preparation method and application thereof, and belongs to the technical field of aqueous zinc ion batteries. The application obtains a mixed slurry by dispersing sulfonated polyether ether ketone resin and metal organic framework powder in an organic solvent, reasonably controls the concentration, and utilizes the difference in sedimentation rates to make the metal organic framework material and the sulfonated polyether ether ketone sequentially deposit on the surface of a zinc metal electrode to obtain the zinc metal negative electrode with double-layer protective films, wherein the lower layer is a metal organic framework film, and the upper layer is a sulfonated polyether ether ketone film. The double-layer protective films combine the high Young's modulus of the metal organic framework material and the high tensile strength of the sulfonated polyether ether ketone, and have high zinc ion conductivity, can induce uniform zinc deposition, and inhibit the formation of dendrites. The zinc metal negative electrode has a greatly improved cycle life, the preparation method is simple, batch production is easy, and the zinc metal negative electrode has a wide application prospect in the energy storage technology field.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aqueous zinc-ion batteries, and particularly relates to a zinc metal negative electrode with double-layer protective films and a preparation method and application thereof. BACKGROUND

[0002] To promote the realization of the carbon peak and carbon neutralization targets, the proportion of new energy such as wind energy and solar energy in future energy consumption will increase rapidly. However, the above-mentioned energy is susceptible to seasonal and weather factors, and has great output instability, so it needs to be matched with energy storage facilities to achieve smooth output. Electrochemical energy storage technology has the advantages of high efficiency and flexible use, and has become the focus of research by researchers in recent years. Lithium-ion batteries are a relatively mature electrochemical energy storage technology, but due to high cost and serious safety problems, their scale application in the energy storage field is limited.

[0003] Aqueous zinc-ion batteries are a kind of secondary batteries with zinc salt aqueous solution as electrolyte, which have the advantages of safety, low cost and environmental friendliness, and show great potential for energy storage applications, and have recently become a hot topic of concern. However, during the charge and discharge cycle of the aqueous zinc-ion battery, the zinc metal negative electrode will produce uneven deposition, and then form dendrites, which will pierce through the separator and cause short circuit of the battery. In recent years, researchers have developed various strategies to solve this problem, such as building surface coatings, designing deposition substrates, and adding electrolyte additives. Li et al. deposited a 3DZF2 array on the surface of the zinc metal negative electrode, and at the same time, regulated the zinc ion flux and reduced the zinc ion desolvation activation energy. At a current density of 1 mAcm -2 and a surface capacity of 1 mAhcm -2 , the zinc electrode can be cycled for 800 hours (Adv. Mater. 2021, 2007388). Jang Wook Choi et al. used gelatin to induce directional deposition of zinc, and under the above conditions, the zinc life can reach 4000 hours (Adv. Energy Mater. 2021, 2100676). The above research results provide ideas for inhibiting zinc dendrite growth, but due to the insufficient conductivity and mechanical strength of the coating, it can only work at a small current density and surface capacity, and still cannot meet the actual application requirements. It is of great significance to explore new solutions for the scale application of zinc-ion batteries in energy storage. SUMMARY

[0004] In view of the zinc metal negative electrode dendrite problem, the application provides a zinc metal negative electrode with double-layer protective films and a preparation method and application thereof, which are simple in process and easy to mass produce.

[0005] The technical scheme of the application is as follows:

[0006] The application provides a zinc metal negative electrode with double-layer protective films, which is based on a zinc metal electrode, and the surface of the zinc metal electrode is sequentially attached with a metal organic framework protective film and a sulfonated polyether ether ketone protective film.

[0007] Further, the zinc metal negative electrode is prepared by dispersing the sulfonated polyether ether ketone resin and the metal organic framework powder in an organic solvent to obtain a mixed slurry, reasonably controlling the concentration of the mixed slurry, and sequentially depositing the metal organic framework powder and the sulfonated polyether ether ketone resin on the surface of the zinc metal electrode by using the difference in sedimentation rate.

[0008] Further, the main components of the metal organic framework powder are one or a combination of two or more of UIO-66, UIO-66-SO3H, UIO-66COOH, UIO-66-NH2 and UIO-66-Br.

[0009] Another aspect of the application provides a preparation method of the above-mentioned zinc metal negative electrode with double-layer protective films, which mainly comprises the following steps:

[0010] (1) dissolving the sulfonated polyether ether ketone resin in an organic solvent to obtain a solution with a mass fraction of 5% to 10%;

[0011] (2) adding the metal organic framework powder into the solution obtained in step (1) and uniformly dispersing by ultrasonic to obtain a suspension;

[0012] (3) uniformly coating the suspension obtained in step (2) on the zinc metal electrode by drop coating or blade coating, and drying to obtain the zinc metal negative electrode with double-layer protective films.

[0013] Further, the organic solvent in step (1) comprises one or a combination of two or more of N,N dimethylacetamide, N,N dimethylformamide or dimethyl sulfoxide.

[0014] Further, the mass ratio of the sulfonated polyether ether ketone resin to the metal organic framework powder in the suspension in step (2) is 1:3 to 1:5.

[0015] Further, the zinc metal electrode in step (3) comprises a zinc foil or a zinc plate.

[0016] Further, the drop amount of the suspension on the surface of the zinc metal electrode in step (3) is 1 to 20 uL cm -2 .

[0017] Further, the drying process in step (3) is drying at 40 to 80℃ under vacuum for 4 to 12h.

[0018] The application also provides application of the zinc metal negative electrode with the double-layer protective film in a water-based zinc ion battery.

[0019] Further, the battery assembled by the zinc metal negative electrode with the double-layer protective film has a cycle life of more than 400 h under the condition that the current density is 10 mAcm -2 and the surface capacity is 10 mAhcm -2 .

[0020] Compared with the prior art, the application has the following characteristics:

[0021] In the application, the organic metal framework material (UIO-66 series) and the sulfonated polyether ether ketone polymer are used as the double-layer protective film of the zinc metal negative electrode, the lower UIO-66 series material has a high Young's modulus and can relieve zinc from penetrating the coating, the upper sulfonated polyether ether ketone has a high tensile strength and can relieve the volume change in the zinc deposition / dissolution process, and in addition, both the upper and lower materials have high zinc ion conductivity and can adjust the uniformity of zinc ions on the negative electrode surface. Therefore, the protective film can ensure a flat morphology in the charge / discharge cycle process, effectively solve the dendrite problem, improve the cycle performance of the zinc metal electrode, and has a simple scheme and is easy to industrialize, thus having a wide application prospect in the energy storage technology field. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the application, the drawings involved in the embodiments will be briefly introduced below.

[0023] Figure 1 FIG. 1 is a protective film structure diagram of the zinc metal negative electrode with the protective film in the embodiment 1 of the application.

[0024] Figure 2 FIG. 2 is a cycle performance diagram of the Zn / / Zn symmetric battery assembled by the zinc metal electrode in the embodiment 1 of the application.

[0025] Figure 3 FIG. 3 is a scanning electron microscope (SEM) diagram of the zinc metal electrode after being cycled for 400 hours in the embodiment 1 of the application.

[0026] Figure 4 FIG. 4 is a cycle performance diagram of the Zn / / Zn symmetric battery assembled by the zinc metal negative electrode in the comparative example 1.

[0027] Figure 5 FIG. 5 is a cycle performance diagram of the Zn / / Zn symmetric battery assembled by the zinc metal negative electrode in the comparative example 2.

[0028] Figure 6 FIG. 6 is a cycle performance diagram of the Zn / / Zn symmetric battery assembled by the zinc metal negative electrode in the comparative example 3. DETAILED DESCRIPTION

[0029] The application will be described in detail below with reference to examples, but the embodiments of the application are not limited thereto. It is obvious that the examples described below are only some of the embodiments of the application, and other similar embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0030] The cycle performance test of the Zn / / Zn symmetric battery described in Example 1 and Comparative Examples 1-3 was carried out under the following conditions: the simulation battery used a CR2032 type system of button cell, wherein the electrode was the electrode described in Example 1 and Comparative Examples 1-3, the electrolyte was a 2M zinc sulfate solution, and the separator was a glass fiber membrane. The test was carried out by constant current charging and discharging, and the current density was 10 mA cm -2 , and the surface capacity was 10 mAh cm -2 .

[0031] Example 1

[0032] A zinc metal negative electrode with a protective film was prepared by the following experimental steps:

[0033] 20 mg of sulfonated polyether ether ketone was dissolved in 380 mg of N,N-dimethylacetamide, and then 80 mg of metal organic framework powder UIO-66-SO3H powder was added to the solution. After ultrasonic dispersion for 1-2 hours, a suspension was obtained. 5 uL of the suspension was dropped on a 0.785 cm -2 zinc foil, and dried at 40°C under vacuum conditions for 4-12 h to obtain a zinc metal negative electrode with a double-layer protective film (named US-SPEEK).

[0034] The cycle performance simulation of the Zn / / Zn symmetric battery used a CR2032 type system of button cell. Among them, the electrode was the zinc metal foil obtained in the embodiment.

[0035] The cycle life of the Zn / / Zn symmetric battery assembled using the zinc metal negative electrode in the embodiment was at least 400 h (as shown in Figure 2 . As can be seen from the scanning electron microscope image (SEM), the morphology of zinc after 400 h of cycle was still relatively flat (as shown in Figure 3 .

[0036] Comparative Example 1

[0037] The bare zinc foil without surface treatment was directly used as the electrode to assemble the symmetric battery.

[0038] The results are shown in Figure 4 . The cycle life of the Zn / / Zn symmetric battery assembled using the zinc foil electrode described in Comparative Example 1 was only 20 h.

[0039] Comparative Example 2

[0040] Dissolve 20 mg of sulfonated polyether ether ketone in 380 mg of N,N-dimethylacetamide, then add 180 mg of metal-organic framework powder UIO-66-SO3H to the solution. After ultrasonic dispersion for 1–2 hours, a suspension is obtained. Take 5 μL of the suspension and drop it onto a 0.785 cm⁻¹ plate. -2 On zinc foil, the zinc metal anode (named US) with a single protective film is obtained by drying under vacuum at 40°C for 4 to 12 hours. The main component of the protective film is UIO-66-SO3H.

[0041] The results are as follows Figure 5 As shown, the Zn / / Zn symmetric cell assembled using the zinc metal electrode described in Comparative Example 2 has a cycle life of 120 h.

[0042] Comparative Example 3

[0043] Dissolve 20 mg of sulfonated polyether ether ketone in 380 mg of N,N-dimethylacetamide, and sonicate for 1–2 hours to obtain a solution. Take 5 μL and drop it onto a 0.785 cm⁻¹ solution. -2 On zinc foil, the zinc metal negative electrode (named SPEEK) is dried under vacuum at 40°C for 4–12 h to obtain a single protective film. The protective film is composed of sulfonated polyether ether ketone.

[0044] The results are as follows Figure 6 As shown, the Zn / / Zn symmetric cell assembled using the zinc electrode described in Comparative Example 3 has a cycle life of 175 h.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A zinc metal negative electrode with a double layer of protective films, characterized in that, The zinc metal negative electrode is based on a zinc metal electrode, and the surface of the base is sequentially attached with a metal organic framework protective film and a sulfonated polyether ether ketone protective film; (1) dissolving the sulfonated polyether ether ketone resin in an organic solvent to obtain a solution with a mass fraction of 5%-10%; (2) adding metal organic framework powder into the solution obtained in step (1) and uniformly dispersing to obtain a suspension; (3) uniformly coating the suspension obtained in step (2) on a zinc metal electrode by using a drop coating method or a scraping coating method, and drying to obtain a zinc metal negative electrode with double-layer protective films; In step (2), the mass ratio of the sulfonated polyether ether ketone resin to the metal organic framework powder in the suspension is 1:3-1:5; In step (3), the specific process of drying is drying at 40-80 ℃ under vacuum conditions for 4-12 h; The zinc metal negative electrode is prepared by dispersing the sulfonated polyether ether ketone resin and the metal organic framework powder in an organic solvent to obtain a mixed slurry, adjusting the concentration of the mixed slurry, and making the metal organic framework powder and the sulfonated polyether ether ketone resin sequentially deposit on the surface of the zinc metal electrode by using the difference in sedimentation rate; The metal organic framework powder is primarily composed of UIO 66、UIO 66 SO3H, UIO 66 COOH, UIO 66 NH2and UIO 66 one or more combinations of two or more of Br.

2. The zinc metal negative electrode of claim 1, wherein, The organic solvent described in step (1) is N,N dimethylacetamide, N,N dimethylformamide or dimethylsulfoxide, or a combination of one or more thereof.

3. The zinc metal negative electrode of claim 1, wherein, In step (3), the zinc metal electrode includes a zinc foil or a zinc plate.

4. The zinc metal negative according to claim 1, wherein, The amount of the suspension described in step (3) to be dropped on the surface of the zinc metal electrode is 1 to 20 uL cm -2 .

5. The zinc metal anode with double protection films of any one of claims 1 4. Use of the zinc metal anode with double protection films of any one of claims 1-3 in aqueous zinc-ion batteries.

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