Aqueous zinc ion battery and protection method and protection layer of negative electrode of aqueous zinc ion battery

Abstract

The invention relates to the technical field of water-based zinc ion batteries, in particular to a water-based zinc ion battery and a protection method and a protection layer of a negative electrode of the water-based zinc ion battery. The method comprises the following steps: coating the surface of a zinc negative electrode of the aqueous zinc ion battery with a layer of polybenzimidazole, and curing to form a film; the coated zinc negative electrode is soaked in a soluble zinc salt solution, so that polybenzimidazole and zinc salt are subjected to a metal coordination reaction, and a protective layer is formed after drying; and performing laser carbonization treatment on the protective layer subjected to metal coordination to form a carbonized protective layer. The thickness of the protective layer is 50-100 [mu] m, preferably 70 [mu] m, zinc negative electrode corrosion, dendritic crystal growth and hydrogen evolution reaction can be effectively inhibited, and the cycle stability of the battery is remarkably improved. The battery adopting the protective layer shows excellent performance in a long-cycle test, the interface impedance is reduced, and the electrochemical stability is enhanced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aqueous zinc-ion batteries, and particularly relates to an aqueous zinc-ion battery and a protection method and a protection layer for a negative electrode of the aqueous zinc-ion battery. BACKGROUND

[0002] With the increasing depletion of traditional fuel resources, energy problems have become an important concern for future social development. In recent years, the rapid development of energy storage technology has provided a key approach to solving energy problems. Aqueous zinc-ion batteries have shown great application potential in the field of new energy storage due to their high safety, low cost, and environmental friendliness. An aqueous zinc-ion battery mainly consists of a positive electrode, an electrolyte, a separator, and a zinc negative electrode, and energy storage and release are achieved through ion transfer between the positive and negative electrodes. However, aqueous zinc-ion batteries still face many challenges in practical applications, among which the stability problem of the zinc negative electrode is particularly prominent. The zinc negative electrode is prone to corrosion, dendrite growth, and hydrogen evolution during charging and discharging, which not only affects the cycle life of the battery, but also can lead to rapid performance degradation and even failure of the battery.

[0003] At present, researchers have proposed various solutions to the stability problem of the zinc negative electrode, including constructing a protection layer, optimizing the composition of the electrolyte, and improving the battery structure. Among them, constructing a protection layer is an efficient and commonly used strategy. By introducing a protection layer between the zinc negative electrode and the electrolyte, direct contact between zinc and corrosive electrolyte can be effectively avoided, corrosion passivation can be reduced, and uniform zinc ion deposition can be guided, thereby inhibiting the generation of dendrites and hydrogen evolution. However, there are still deficiencies in the selection and preparation method of existing protection layer materials. For example, the physical and electrochemical stability of some protection layer materials is poor, making it difficult to maintain performance in long-term cycling; while some materials have good stability, but have insufficient active sites or insufficient conductivity, which cannot effectively regulate zinc ion transport behavior, resulting in reduced battery efficiency. Therefore, developing a protection layer material with stability, conductivity, and zinc wettability, and optimizing its preparation process, has become a key technical problem for improving the performance of aqueous zinc-ion batteries. SUMMARY

[0004] In view of the problems in the prior art, the application proposes a protection method and a protection layer for an aqueous zinc-ion battery and its negative electrode. By constructing a protection layer based on polybenzimidazole on the surface of the zinc negative electrode, and combining metal coordination and laser carbonization treatment, the structural characteristics of the zinc negative electrode are optimized. The protection layer can significantly inhibit the corrosion, dendrite growth, and hydrogen evolution of the zinc negative electrode, thereby improving the cycle stability and overall efficiency of the battery. This innovative method provides a new technical path for the performance improvement of aqueous zinc-ion batteries, and has important research value and application prospect.

[0005] The technical scheme of the application is as follows: The first technical purpose of the present application is to provide a method for protecting a negative electrode of an aqueous zinc-ion battery, comprising the following steps: coating a layer of polybenzimidazole on the surface of the zinc negative electrode of the aqueous zinc-ion battery and curing the film; immersing the coated zinc negative electrode in a soluble zinc salt solution to cause metal coordination reaction between the polybenzimidazole and the zinc salt, and forming a protective layer after drying; forming a carbonized protective layer by laser carbonization treatment of the metal-coordinated protective layer; The method suppresses zinc negative electrode corrosion, dendrite growth and hydrogen evolution reaction by constructing a carbonized protective layer, thereby improving the cycle stability of the zinc negative electrode.

[0006] Further, the curing film forming conditions of the above method are 80-120°C for 3-5 hours.

[0007] Further, the above method, the concentration of the soluble zinc salt solution is 0.02-2 mol / L. Further, the above method, the soluble zinc salt is zinc chloride, and the solvent is N,N-dimethylformamide.

[0008] Further, the above method, the zinc negative electrode immersion time is 3-5 min.

[0009] Further, the above method, the drying temperature is 50-80°C, and the drying time is 1-3 hours.

[0010] Further, the above method, the power of the laser carbonization treatment is 5-20 W, the scanning speed is 100-500 mm / s, and the scanning path line spacing is 0.05-0.1 mm.

[0011] The second technical purpose of the present application is to provide a protective layer for a negative electrode of an aqueous zinc-ion battery, which comprises: The substrate is a zinc negative electrode; The surface is covered with a carbonized polybenzimidazole layer; The total thickness of the protective layer is 50-100 μm, preferably 70 μm.

[0012] The third technical purpose of the present application is an aqueous zinc-ion battery, which is composed of a positive electrode, a negative electrode, a separator and an electrolyte, and the negative electrode comprises the above protective layer. Further, the above battery, the electrolyte is a 2 mol / L zinc sulfate solution, and the separator is a glass fiber filter membrane.

[0013] Advantages and beneficial effects of the present application: The present invention successfully solves the problems of corrosion, dendrite growth and hydrogen evolution reaction of zinc negative electrodes in traditional aqueous zinc ion batteries by constructing a PBI protective layer on the surface of the zinc negative electrode that has been metal coordinated and laser treated. The battery interface impedance is significantly reduced, and the battery's cycle stability, interface transmission characteristics and overall electrochemical performance are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is the 5 mA cm of the zinc symmetrical battery in Example 1 -2 , 1mAhcm -2 Long cycle test chart; Figure 2 is the 5 mA cm of the zinc symmetrical battery in Example 1 -2 , 5mAhcm -2 Long cycle test chart; Figure 3 is the 10 mA cm of the zinc symmetrical battery in Example 1 -2 , 1mAhcm -2 Long cycle test chart; Figure 4 is the 5 mA cm of the zinc symmetrical battery in Example 2 -2 , 1mAhcm -2 Long cycle test chart; Figure 5 is the 5 mA cm of the zinc symmetrical battery in Example 3 -2 , 1mAhcm -2 Long cycle test chart; Figure 6 is the 5 mA cm of the zinc symmetrical battery in Example 3 -2 , 1mAhcm -2 Long cycle test chart; Figure 7 5 mA cm for the zinc symmetrical battery in Comparative Example 1 -2 , 1mAhcm -2 Long cycle test chart; Figure 8 5 mA cm for the zinc symmetrical battery in Comparative Example 1 -2 , 5mAhcm -2 Long cycle test chart; Figure 9 is 10 mA cm of the zinc symmetrical battery in Comparative Example 1 -2 , 1mAhcm -2 Long cycle test chart; Figure 10 This is the SEM image of the carbonized protective layer in Example 1. DETAILED DESCRIPTION

[0015] Next, the specific implementation of the present invention will be further described in detail with reference to the accompanying drawings and examples.

[0016] Example 1

[0017] In this embodiment, the entire preparation process is carried out at room temperature and normal pressure, and specifically includes the following steps: 1. Preparation of zinc negative electrode protective layer: 1) Use 1000-grit and 2000-grit sandpaper to polish a 50-μm-thick zinc foil, then coat it with 150-μm-thick polybenzimidazole (PBI) and cure it at 100°C for 4 hours. 2) Add 100 ml of DMF to a beaker and add 27.26 g of zinc chloride while stirring at medium speed in an ultrasonic bath to obtain a 0.2 mol / L zinc chloride solution. 3) Soak the zinc foil with the PBI film in zinc chloride solution for 5 minutes, then dry it in a vacuum drying oven at 60°C for 2 hours; 4) The dried zinc foil was laser carbonized using the following process parameters: laser carbonization power of 20 W, scanning speed of 100 mm / s, and scanning path line spacing of 0.05 mm. The resulting protective layer had a thickness of 70 μm.

[0018] 2. Preparation of zinc negative electrode: The zinc foil with a protective layer was cut into discs with a diameter of 12 mm, ultrasonically cleaned with anhydrous ethanol for 20 minutes, and then dried for use.

[0019] 3. Battery assembly: The zinc foil was used as the negative electrode, the glass fiber filter membrane was used as the diaphragm, 2 mol / L zinc sulfate solution was used as the electrolyte, and the positive electrode was V2O5-NH 4+ @Ti, assembled into a CR2032 battery.

[0020] 4. Battery test: Place the above battery in a battery tester and set the condition to 5mAcm -2 , fixed charge and discharge capacity is 1mAhcm -2 , and conduct long cycle performance test, the results are attached Figure 1 shown.

[0021] The above battery was placed in a battery tester, the setting conditions were 5mAcm-2, the charge and discharge capacity was fixed at 5mAhcm-2, and a long cycle performance test was performed. The results are attached. Figure 2 shown.

[0022] Place the above battery in a battery tester and set the condition to 10mAcm -2, fixed charge-discharge capacity of 1 mAh cm -2 , long cycle performance test results attached Figure 3 as shown.

[0023] It can be seen from Figures 1-3 that the zinc symmetric battery in this embodiment shows excellent stability in long cycle test, and these experimental results show that the protective layer of the present application is not only suitable for low current density conditions, but also can maintain stable electrochemical performance under high current density.

[0024] characterization test The above negative electrode with protective layer was subjected to SEM test. The results are shown in Figure 10 , the interwoven structure after carbonization guides the uniform deposition of zinc ions and inhibits dendrite growth.

[0025] Example 2

[0026] The difference between this embodiment and Example 1 is: A 200-μm-thick polybenzimidazole (PBI) was coated on the zinc foil, and after laser treatment, the thickness of the formed protective layer was 80 um.

[0027] Battery test only needs to be carried out at 5 mA cm -2 , 1 mAh cm -2 long cycle performance test. The results are shown in Figure 4 .

[0028] Example 3

[0029] The difference between this embodiment and Example 1 is: A 100-μm-thick polybenzimidazole (PBI) was coated on the zinc foil, and after laser treatment, the thickness of the formed protective layer was 50 um.

[0030] Battery test only needs to be carried out at 5 mA cm -2 , 1 mAh cm -2 long cycle performance test. The results are shown in Figure 5 .

[0031] Example 4

[0032] The difference between this embodiment and Example 1 is: The process parameters of laser carbonization are: the power of laser carbonization treatment is 20 W, the scanning speed is 200 mm / s, and the scanning path line spacing is 0.05 mm. The results are shown in Figure 6 .

[0033] Comparative Example 1 In this comparative example, all processes were carried out at room temperature and normal pressure, and the specific implementation steps were as follows, I. Preparation of electrode Use 1000-mesh and 2000-mesh sandpaper to polish 50-micron-thick zinc foil, cut it into discs with a diameter of 12 mm, and ultrasonically clean it with anhydrous ethanol for 20 minutes and then dry it for use.

[0034] 2. Battery Assembly The zinc foil was used as the electrode and the glass fiber filter membrane was used as the diaphragm. -1 Zinc sulfate solution is the electrolyte, and the positive electrode is V2O5-NH 4+ @Ti, assembled into a CR2032 battery.

[0035] 3. Battery Test Place the above battery in a battery tester and set the condition to 5mAcm -2 , fixed charge and discharge capacity is 1mAhcm -2 , and conduct long cycle performance test, the results are attached Figure 7 shown.

[0036] Place the above battery in a battery tester and set the condition to 5mAcm -2 , fixed charge and discharge capacity is 5mAhcm -2 , and conduct long cycle performance test, the results are attached Figure 8 shown.

[0037] Place the above battery in a battery tester and set the condition to 10mAcm -2 , fixed charge and discharge capacity is 1mAhcm -2 , and conduct long cycle performance test, the results are attached Figure 9 shown.

[0038] Depend on Figures 7-9 It can be seen that the zinc symmetrical battery of the comparative example has large fluctuations in the long cycle test, which further reflects that the protective layer of the present invention can significantly improve the cycle stability of the battery.

Claims

1. A method for protecting the negative electrode of an aqueous zinc ion battery, characterized in that: The following steps are involved: A layer of polybenzimidazole is coated on the surface of the zinc negative electrode of the aqueous zinc ion battery and cured to form a film; The coated zinc negative electrode is immersed in a soluble zinc salt solution to allow the polybenzimidazole to undergo a metal coordination reaction with the zinc salt, and a protective layer is formed after drying; The metal-coordinated protective layer is subjected to laser carbonization treatment to form a carbonized protective layer; The method inhibits zinc negative electrode corrosion, dendrite growth and hydrogen evolution reaction by constructing a carbonized protective layer, thereby improving the cycle stability of the zinc negative electrode.

2. A protective layer for an aqueous zinc ion battery negative electrode, characterized in that include: The substrate is a zinc negative electrode; The surface is covered with a carbonized polybenzimidazole layer; The total thickness of the protective layer is 50-100 μm.

3. An aqueous zinc ion battery, characterized in that The electrolyte comprises a positive electrode, a negative electrode, a separator and an electrolyte, wherein the negative electrode comprises the protective layer according to claim 1 or the protective layer according to claim 2.

4. The method according to claim 1, wherein The curing conditions for film formation are 80-120°C for 3-5 hours.

5. The method according to claim 1, wherein The concentration of the soluble zinc salt solution is 0.02-2 mol / L.

6. The method according to claim 5, characterized in that The soluble zinc salt is zinc chloride, and the solvent is N,N-dimethylformamide.

7. The method according to claim 1, characterized in that The zinc negative electrode immersion time is 3~5 min.

8. The method according to claim 1, characterized in that The drying temperature is 50~80℃ and the drying time is 1~3 hours.

9. The method according to claim 1, characterized in that The power of the laser carbonization treatment is 5-20 W, the scanning speed is 100-500 mm / s, and the scanning path line spacing is 0.05-0.1 mm.

10. The battery according to claim 3, characterized in that The electrolyte is a 2 mol / L zinc sulfate solution, and the diaphragm is a glass fiber filter membrane.

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