Method for modifying zinc negative electrode interface through silver nanowires

Abstract

The invention belongs to the technical field of energy storage, and particularly relates to a method for modifying a zinc negative electrode interface by using silver nanowires, which comprises the following steps: step 1, dispersing the silver nanowires with high length-diameter ratio into an organic solvent at a certain concentration; step 2, performing ultrasonic cleaning on the zinc foil, and then coating the silver nanowire dispersion liquid prepared in the step 1 on the surface of the zinc foil; 3, the zinc foil coated with the silver nanowire dispersion liquid in the step 2 is dried, and the zinc foil attached with the silver nanowires is obtained; and 4, the silver nanowires attached to the zinc foil in the step 3 are subjected to hot welding, and the zinc foil coated with the silver nanowire interconnection network is obtained. The silver nanowire conductive network formed on the surface of the zinc foil enables the current to be uniformly distributed, so that the formation and growth of zinc dendrites are inhibited, and the electroplating / stripping cycle time of the zinc negative electrode is remarkably prolonged; and the silver nanowire conductive network can also adjust the interface property of the zinc negative electrode and the electrolyte, reduce the corrosion current and enhance the stability of the electrode.

Description

Technical Field

[0001] The invention belongs to the technical field of energy storage, and in particular relates to a method for modifying the interface of a zinc negative electrode with silver nanowires. Background Art

[0002] With the consumption of fossil energy and the environmental problems caused by the use of fossil energy, finding sustainable clean energy has important strategic value. Since renewable energy such as solar energy, bioenergy, wind energy and tidal energy are intermittent, random and uncontrollable, it is difficult to supply them stably and cannot meet the urgent demand for energy in society. Therefore, the development of new energy storage technology and the efficient use of renewable energy are the key directions of current research. Among the many energy storage technologies, electrochemical energy storage technology has attracted much attention due to its advantages such as high energy conversion efficiency, flexibility, convenience and simple maintenance.

[0003] Aqueous zinc-ion batteries have great application potential due to their high zinc reserves, high theoretical capacity, low redox potential, low cost, safety and non-toxicity. Despite the above advantages of zinc-ion batteries, the growth of zinc dendrites in actual applications will cause the coulombic efficiency of zinc-ion batteries to decrease, the cycle stability to deteriorate, the reversibility to be poor, and the capacity to decay, which is one of the main challenges faced by the zinc negative electrode of zinc-ion batteries. In the process of zinc electroplating / stripping, the non-uniform deposition caused by the uneven electric field distribution is the main reason for the formation of zinc dendrites. Silver nanowires with high aspect ratio have excellent conductivity and high specific surface area. By constructing a silver nanowire conductive network on the surface of the zinc negative electrode, the current distribution on the surface of the zinc negative electrode can be uniform, thereby inhibiting the growth of zinc dendrites; at the same time, the interfacial properties of the zinc negative electrode can be adjusted to reduce the self-corrosion phenomenon of the zinc negative electrode. Summary of the invention

[0004] Aiming at the zinc dendrite growth problem existing in the negative electrode of zinc ion battery, the purpose of the present invention is to provide a method for modifying the interface of zinc negative electrode with silver nanowires. With high aspect ratio silver nanowires as conductive materials, the silver nanowires are loaded on the surface of zinc negative electrode by drip coating, scraping, spin coating, or spraying, and a stable silver nanowire conductive network is formed by thermal welding, thereby forming an artificial interface layer on the surface of zinc foil that can make the current density evenly distributed, so as to inhibit the formation and growth of dendrites in zinc ion batteries. This method is simple to operate and can significantly improve the cycle performance of zinc negative electrode.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for modifying the zinc negative electrode interface with silver nanowires, characterized in that it comprises the following steps:

[0007] Step 1: dispersing high aspect ratio silver nanowires in an organic solvent at a certain concentration;

[0008] Step 2: ultrasonically clean the zinc foil, and then apply the silver nanowire dispersion prepared in step 1 to the surface of the zinc foil;

[0009] Step 3: drying the zinc foil coated with the silver nanowire dispersion in step 2 to obtain the zinc foil with silver nanowires attached;

[0010] Step 4: thermally weld the silver nanowires attached to the zinc foil in step 3 to obtain a zinc foil coated with an interconnected network of silver nanowires.

[0011] In some embodiments, in step 1, the aspect ratio of the silver nanowires used is greater than 2000, the solvent for dispersing the silver nanowires is one of ethanol, N-methylpyrrolidone, dimethylamide, and ethylene glycol, and the solid content of the silver nanowires is 1-5 mg / mL.

[0012] In some embodiments, in step 2, the ultrasonic cleaning solvent is anhydrous ethanol, and the ultrasonic time is 5-10 min.

[0013] In some embodiments, in step 2, the silver nanowires may be loaded on the surface of the zinc foil by drop coating, scraping, spin coating or spray coating.

[0014] In some embodiments, in step 3, the drying process uses a drying or blowing method to fix the silver nanowires on the surface of the zinc foil.

[0015] In some embodiments, in step 4, the thermal welding temperature is 240-280° C., inert gas protection such as argon and nitrogen is used during the thermal welding process, and the thermal welding time is 1-3 h.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The present invention uses silver nanowires with a high aspect ratio to form a silver nanowire conductive network on the surface of the zinc foil, thereby improving the distribution uniformity of the current density on the surface of the zinc negative electrode, thereby inhibiting the growth of zinc dendrites and improving the cycle stability of the zinc ion battery;

[0018] (2) The zinc negative electrode is modified with silver nanowires, which increases the nucleation overpotential of zinc, is conducive to the formation of fine grains, thereby reducing the formation of dendrites;

[0019] (3) Using silver nanowires to modify the zinc negative electrode can reduce the corrosion current density and weaken the self-corrosion of zinc in water, thereby extending the life of the battery;

[0020] (4) The zinc anode modified with silver nanowires is 1 mA / cm 2 , 1mAh / cm 2 The cycle time exceeds 1500 h under the conditions of modified zinc anode, which is significantly improved compared with the cycle time of about 300 h of unmodified bare zinc anode. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is 1 mA / cm 2 , 1 mAh / cm 2 Under the same conditions, the electroplating / stripping cycle comparison diagram of the modified zinc negative electrode symmetrical battery in Example 2 and the unmodified bare zinc symmetrical battery in Comparative Example 1 shows that the cycle time of the modified zinc negative electrode is significantly improved.

[0022] Figure 2 is 5 mA / cm 2 , 1 mAh / cm 2 Under the same conditions, the electroplating / stripping cycle comparison diagram of the modified zinc negative electrode symmetrical battery in Example 2 and the unmodified bare zinc symmetrical battery in Comparative Example 1 shows that the cycle time of the modified zinc negative electrode is significantly improved.

[0023] Figure 3 This is a cycle diagram of the modified zinc negative electrode symmetrical battery in Example 2 at different current densities. After cycling at different current densities, its overpotential remains consistent with that before cycling, indicating that the modified zinc negative electrode has good rate performance.

[0024] Figure 4 It is the Tafel curve of the modified zinc negative electrode symmetrical battery in Example 2 and the bare zinc symmetrical battery in Comparative Example 1. The modified zinc negative electrode has a lower corrosion current density, indicating that the modified zinc negative electrode has stronger corrosion resistance.

[0025] Figure 5 is 1 mA / cm 2 The zinc ion electroplating time-voltage curves of the modified zinc negative electrode in Example 2 and the bare zinc negative electrode in Comparative Example 1 show that the modified zinc negative electrode has a higher nucleation overpotential in the nucleation stage. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are described in detail below. The following embodiments are implemented on the premise of the technical solution of the invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0027] Example 1

[0028] The silver nanowire dispersion with an aspect ratio of about 2400 was prepared into a 1 mg / mL ethanol dispersion. The zinc foil was ultrasonically cleaned twice with anhydrous ethanol as the cleaning solvent. Each ultrasonic washing time was 10 min. After the zinc foil was dried, the silver nanowire dispersion was scraped on the surface of the zinc foil using a Meyer rod. After drying, the zinc foil with silver nanowires attached was transferred to a tubular atmosphere furnace and treated at 250 °C for 2 h under the protection of nitrogen. The prepared modified zinc negative electrode was cut into discs with a diameter of 14 mm, and a glass fiber was used as a separator. A 2 M ZnSO 4 The solution was used as the electrolyte, and CR2032 button cells were assembled for electrochemical performance testing. Tafel curve testing was performed using a CHI660E electrochemical workstation, and constant current charge and discharge cycle testing and constant current discharge testing were performed on a Blue Electric automatic battery testing system.

[0029] Example 2

[0030] The silver nanowire dispersion with an aspect ratio of about 2400 was prepared into a 3 mg / mL ethanol dispersion. The zinc foil was ultrasonically cleaned twice with anhydrous ethanol as the cleaning solvent. Each ultrasonic washing time was 10 min. After the zinc foil was dried, the silver nanowire dispersion was scraped on the surface of the zinc foil using a Meyer rod. After drying, the zinc foil with silver nanowires attached was transferred to a tubular atmosphere furnace and treated at 250 °C for 2 h under the protection of nitrogen. The prepared modified zinc negative electrode was cut into a disc with a diameter of 14 mm, and a glass fiber was used as a separator. The concentration of 2 M ZnSO 4 The solution was used as the electrolyte, and CR2032 button cells were assembled for electrochemical performance testing. Tafel curve testing was performed using a CHI660E electrochemical workstation, and constant current charge and discharge cycle testing and constant current discharge testing were performed on a Blue Electric automatic battery testing system.

[0031] Example 3

[0032] The silver nanowire dispersion with an aspect ratio of about 2400 was prepared into a 5 mg / mL ethanol dispersion. The zinc foil was ultrasonically cleaned twice with anhydrous ethanol as the cleaning solvent. Each ultrasonic washing time was 10 min. After the zinc foil was dried, the silver nanowire dispersion was scraped on the surface of the zinc foil using a Meyer rod. After drying, the zinc foil with silver nanowires attached was transferred to a tubular atmosphere furnace and treated at 250 °C for 2 h under the protection of nitrogen. The prepared modified zinc negative electrode was cut into discs with a diameter of 14 mm, and a glass fiber was used as a separator. The concentration of 2 M ZnSO 4 The solution was used as the electrolyte, and CR2032 button cells were assembled for electrochemical performance testing. Tafel curve testing was performed using a CHI660E electrochemical workstation, and constant current charge and discharge cycle testing and constant current discharge testing were performed on a Blue Electric automatic battery testing system.

[0033] Comparative Example 1

[0034] The zinc foil was ultrasonically cleaned twice with anhydrous ethanol as the cleaning solvent, and each ultrasonic cleaning time was 10 min. After the zinc foil was dried, it was transferred to a tubular atmosphere furnace and treated at 250 °C for 2 h under the protection of nitrogen. The prepared zinc negative electrode was cut into discs with a diameter of 14 mm, and a glass fiber was used as a separator. The concentration of 2 M ZnSO 4 The solution was used as the electrolyte, and CR2032 button cells were assembled for electrochemical performance testing. Tafel curve testing was performed using a CHI660E electrochemical workstation, and constant current charge and discharge cycle testing and constant current discharge testing were performed on a Blue Electric automatic battery testing system.

[0035] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A method for modifying the zinc negative electrode interface with silver nanowires, characterized in that: The steps include: Step 1: dispersing high aspect ratio silver nanowires in an organic solvent at a certain concentration; Step 2: ultrasonically clean the zinc foil, and then apply the silver nanowire dispersion prepared in step 1 to the surface of the zinc foil; Step 3: drying the zinc foil coated with the silver nanowire dispersion in step 2 to obtain the zinc foil with silver nanowires attached; Step 4: thermally weld the silver nanowires attached to the zinc foil in step 3 to obtain a zinc foil coated with an interconnected network of silver nanowires.

2. The method for modifying the zinc negative electrode interface with silver nanowires according to claim 1, characterized in that: In the step 1, the aspect ratio of the silver nanowires used is greater than 2000, the organic solvent for dispersing the silver nanowires is one of ethanol, N-methylpyrrolidone, dimethylamide, and ethylene glycol, and the solid content of the silver nanowires in the dispersion is 1-5 mg / mL.

3. The method for modifying the zinc negative electrode interface with silver nanowires according to claim 1, characterized in that: In step 2, the ultrasonic cleaning solvent is anhydrous ethanol, and the ultrasonic time is 5-10 min.

4. The method for modifying the zinc negative electrode interface with silver nanowires according to claim 1, characterized in that: In the step 2, the silver nanowires may be loaded on the surface of the zinc foil by drop coating, scraping, spin coating or spraying.

5. The method for modifying the zinc negative electrode interface with silver nanowires according to claim 1, characterized in that: In step 3, the drying process adopts a drying or blowing method to fix the silver nanowires on the surface of the zinc foil.

6. The method for modifying the zinc negative electrode interface with silver nanowires according to claim 1, characterized in that: In step 4, the heat welding temperature is 240-280° C., inert gas protection such as argon and nitrogen is used during the heat welding process, and the heat welding time is 1-3 hours.

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