Zinc negative electrode with modified polystyrene microsphere self-assembled protective layer as well as preparation method and application of zinc negative electrode

Abstract

The invention relates to the technical field of zinc negative electrodes, in particular to a zinc negative electrode with a modified polystyrene microsphere self-assembled protective layer and a preparation method and application of the zinc negative electrode. The invention relates to a zinc negative electrode with a modified polystyrene microsphere self-assembled protective layer. The zinc negative electrode comprises a zinc foil and aminated polystyrene microspheres which grow on the zinc foil in situ through horizontal evaporation self-assembly. According to the invention, a horizontal evaporation self-assembly method is adopted, disorderly dispersed polystyrene microspheres are used for self-assembly to form a three-dimensional zinc negative electrode protection layer array capable of guiding zinc ions to uniformly deposit and improving zinc ion diffusion kinetics, the growth of zinc dendrites is effectively inhibited, the coulombic efficiency of the zinc negative electrode is remarkably improved, and the cycle life of the zinc negative electrode is remarkably prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of zinc negative electrode, and particularly relates to a zinc negative electrode with a modified polystyrene microsphere self-assembly protective layer and a preparation method and application thereof. BACKGROUND

[0002] Aqueous zinc-ion batteries (AZIBs) are widely regarded as a promising candidate for large-scale energy storage in the future due to their high safety, low cost, and environmental friendliness. However, the application of AZIBs still faces significant challenges in the performance of zinc negative electrodes, especially during long-term cycling. Zinc dendrite growth, hydrogen evolution reaction (HER), and corrosion and passivation problems often occur on the zinc negative electrode. These problems not only lead to the degradation of the performance of the zinc negative electrode, but also significantly reduce the capacity, coulombic efficiency, rate performance, and cycle life of the battery, thereby limiting the widespread application of AZIBs.

[0003] The root cause of these problems occurring on the zinc negative electrode during battery operation is the uneven distribution of the electric field on the surface of the zinc negative electrode during the charging and discharging process of the battery. During the charging process, zinc ions will gather and deposit in areas with a strong electric field, forming zinc dendrites. This not only increases the resistance of the zinc negative electrode, but also exacerbates the unevenness of the electric field inside the battery (hot spot effect), thereby promoting the further growth of the dendrites. In addition, the hydrogen evolution reaction and corrosion / passivation phenomena are also key factors that reduce the stability of the zinc negative electrode, especially under the conditions of high-rate charging and discharging and long-term use, the stability of the zinc negative electrode is further deteriorated.

[0004] In order to solve these problems, various technical solutions have been proposed, including optimizing the electrolyte formula and improving the electrode structure. However, the existing protective layer design has not fully addressed the combined effects of zinc dendrite growth, uneven electric field, and corrosion. Therefore, there is an urgent need to develop a new, simple, and efficient negative electrode protection scheme. SUMMARY

[0005] The present application aims to provide a zinc negative electrode with a modified polystyrene microsphere self-assembly protective layer and a preparation method and application thereof to address the above-mentioned deficiencies of the prior art.

[0006] The first object of the present application is to provide a zinc negative electrode with a modified polystyrene microsphere self-assembly protective layer, which comprises a zinc foil and amino-functionalized polystyrene microspheres self-assembled and grown in situ on the zinc foil.

[0007] Further, the amount of amino-functionalized polystyrene microspheres assembled on the zinc foil is 0.0053-0.0106 mg / cm 2 .

[0008] Further, the preparation method of the amino-modified polystyrene microspheres is as follows: acrylamide is stirred and reacted with the polystyrene emulsion, centrifuged, washed and dried.

[0009] Further, in the polystyrene emulsion, the mass ratio of polystyrene to water is 1-3:97-99.

[0010] Further, the mass ratio of acrylamide to polystyrene is 1:3-4.

[0011] Further, the mass ratio of acrylamide to polystyrene is 1:3.6.

[0012] Further, the particle size of the polystyrene microspheres is 50-700 nm.

[0013] Further, the particle size of the polystyrene microspheres is 50 nm, 100 nm, 300 nm, or 700 nm.

[0014] The second object of the present application is to provide a preparation method of a zinc negative electrode with a modified polystyrene microsphere self-assembled protective layer as described above, comprising the following steps: ultrasonic washing the zinc foil in water and ethanol, and then drying; Preparation of amino-modified polystyrene microspheres and dispersion in ethanol to obtain a modified polystyrene microsphere solution; Slowly add the modified polystyrene microsphere solution to the surface of the zinc foil and stand for self-assembly.

[0015] Further, the concentration of the modified polystyrene microsphere solution is 0.5-2 wt%.

[0016] Further, the self-assembly is carried out at 50-70°C for 4-6 minutes.

[0017] The third object of the present application is to provide an aqueous zinc ion battery comprising the zinc negative electrode with a modified polystyrene microsphere self-assembled protective layer as described above.

[0018] The present application adopts a horizontal evaporation self-assembly method to self-assemble a three-dimensional zinc negative electrode protective layer array with ordered dispersed polystyrene microspheres, which has the functions of guiding uniform zinc ion deposition and improving zinc ion diffusion kinetics. The protective layer constructs a three-dimensional ion diffusion channel network through self-assembly, can effectively uniformize the electric field, and avoid the interference of irregular electric field on zinc deposition. By adjusting the concentration distribution of Zn 2+ , the number of Zn 2+ transfers is significantly increased, the concentration polarization is effectively reduced, a uniform zinc ion concentration field is formed on the surface of the zinc negative electrode, and Zn 2+The flux distribution is more uniform, thereby realizing uniform zinc deposition, effectively inhibiting the growth of zinc dendrites, and significantly improving the coulombic efficiency and cycle life of the zinc negative electrode. In addition, the strong interaction of the polar amide groups grafted on the surface of the polystyrene microspheres with water helps to limit the distribution of free water, promote the desorption of water and zinc ions, and further improve the rapid diffusion of zinc ions and the overall performance of the battery.

[0019] The symmetric zinc ion battery with the zinc negative electrode prepared in the application as the negative current collector exhibits low polarization and long cycle life. In particular, it can have a low polarization of 30 mV and a stable cycle of more than 4000 h at a current density of 2 mA, and under the same conditions, the polarization of the corresponding metal foil is 86 mV, and the cycle life is less than 40 cycles. It also has good performance in zinc-iodine full batteries, with high stability and long cycle life. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Cycle diagram of the symmetric battery assembled by the protective layer of the microspheres with different concentrations; Figure 2 FT-IR spectrum of the modified polystyrene microspheres of Example 1; Figure 3 Scanning electron microscope (SEM) image of the self-assembly of the modified polystyrene microspheres of Example 2; Figure 4 CV test diagram of the zinc-iodine button cell assembled by the APS-1@Zn electrode of Example 2 at 2 mA·cm -2 Current density, 1 mA·h cm -2 Polarization and long cycle diagram of the symmetric button cell below; Figure 5 Zinc ion transfer number test diagram of the modified polystyrene microspheres of Example 2 compared with bare zinc and unmodified polystyrene microspheres; Figure 6 X-ray diffraction (XRD) pattern of APS-1@Zn, APS@Zn, and bare Zn immersed in 2 mol / L ZnSO4 electrolyte for seven days; Figure 7 Cycle test results of the asymmetric button cell assembled by the APS-1@Zn prepared in Example 2 and copper foil; Figure 8 Scanning electron microscope image of the electrode after the APS-1@Zn is cycled and the surface protective layer is removed; Figure 9 CV test diagram of the zinc-iodine button cell assembled by the APS-1@Zn electrode; Figure 10 Rate and long cycle test diagram of the zinc-iodine full cell assembled by the APS-1@Zn electrode. DETAILED DESCRIPTION

[0021] The following is a specific embodiment of the present application and further describes the technical solutions of the present application in conjunction with the drawings, but the present application is not limited to these embodiments.

[0022] Example 1 A modified polystyrene microsphere self-assembled protective layer, comprising modification of polystyrene microspheres, a three-dimensional protective layer grown in situ on a zinc foil by horizontal evaporation self-assembly.

[0023] The modification method of the polystyrene microspheres according to the present application is as follows: First step: 5 g of acrylamide is added to a four-necked flask together with 18.18 g of polystyrene microspheres, the temperature of the flask is maintained at 70°C, and the reaction is carried out under stirring for 10 hours until the reaction is completed, obtaining a white emulsion product.

[0024] Second step: After the reaction is completed, the obtained emulsion product is centrifuged at a speed of 10000 r / min, and the supernatant is discarded. Subsequently, anhydrous ethanol is added for ultrasonic dispersion for 15 minutes, and then centrifugation is performed again.

[0025] Third step: The above washing steps are repeated 5 times to completely remove unreacted monomers, dispersion stabilizers and other impurities.

[0026] Fourth step: The washed product is vacuum dried at room temperature for 12 hours, obtaining white powder-like amino-modified polystyrene (APS-1) nanospheres.

[0027] Example 2 The preparation method of the three-dimensional protective layer grown in situ on a zinc foil by horizontal evaporation self-assembly according to the present application is as follows: First step: Commercial zinc foil (thickness: 100 μm) is cut into discs (diameter: 12 mm) and ultrasonically washed in water and ethanol for 15 min respectively to remove surface impurities and contaminants. Subsequently, the flexible substrate is transferred to an empty beaker and kept in a drying oven at 60°C for 5 hours, obtaining a clean substrate.

[0028] Second step: The modified polystyrene microspheres prepared in Example 1 are dispersed into a colloidal solution (60 μL of 1 wt%) with ethanol as the solvent, slowly added to the surface of the zinc foil, and self-assembled at 60°C for 5 minutes to obtain APS-1@Zn electrode pieces.

[0029] Comparative Example 1 In the second step, polystyrene microspheres are dispersed into a colloidal solution (60 μL of 1 wt%) with ethanol as the solvent, slowly added to the surface of the zinc foil, and self-assembled at 60°C for 5 minutes to obtain APS@Zn electrode pieces. The other steps are the same as in Example 2.

[0030] Comparative Example 2 Second step: The modified polystyrene microspheres prepared in Example 1 were dispersed into a colloidal solution (60 μL 1.5 wt%) with ethanol as the solvent and slowly added onto the surface of a zinc foil. The solution was left to self-assemble at 60 °C for 5 minutes. The other steps were the same as in Example 2.

[0031] Comparative Example 3 Second step: The modified polystyrene microspheres prepared in Example 1 were dispersed into a colloidal solution (60 μL 2.0 wt%) with ethanol as the solvent and slowly added onto the surface of a zinc foil. The solution was left to self-assemble at 60 °C for 5 minutes. The other steps were the same as in Example 2.

[0032] It was observed that, due to the excessive amount of self-assembled polystyrene microspheres, the protective layer formed was not uniform, Figure 1 The cycle diagram of the symmetrical battery assembled with the protective layer of different concentrations of microspheres is shown in Figure 6. Figure 1 It can be seen that the self-assembled coating of 1 wt% polystyrene emulsion showed the smallest polarization voltage and excellent cycle stability in the symmetrical battery test. Compared with other concentrations, the coating formed under the condition of 1 wt% was more uniform, effectively reduced the electrode interface impedance, inhibited the side reaction, and thus significantly improved the overall stability and consistency of the battery.

[0033] The APS-1@Zn electrode was detected and analyzed by Fourier transform infrared spectroscopy, as shown in Figure 5. Figure 2 It is clearly shown that the amide groups are successfully grafted onto the polystyrene microspheres.

[0034] The surface morphology of the APS-1@Zn electrode was detected by scanning electron microscopy (SEM), as shown in Figure 6. Figure 3 It clearly shows the regular array structure. Then, the symmetrical (electrolyte is 2 mol / L ZnS04) battery was assembled with APS-1@Zn, and the symmetrical battery assembled with Bare Zn under the same conditions was used as the control group.

[0035] The experimental results are shown in Figure 7. Figure 4 The results show that the APS-1@Zn symmetrical battery can have a polarization of 56 mV and a stable cycle of 1800 h under a current density of 5 mA. The polarization of the Bare Zn symmetrical battery under the same conditions is 85 mV, and the cycle life is less than 80 cycles.

[0036] The APS-1@Zn prepared in the above Example 2 was tested for zinc ion transfer number using an electrochemical workstation, and the same polystyrene microspheres with a three-dimensional structure self-assembled (APS@Zn) and Bare Zn under the same conditions were used as the control group.

[0037] The experimental results are shown in Figure 8. Figure 5 The results show that the modified polystyrene microspheres indeed have enhanced zinc ion transfer.

[0038] The APS-1@Zn electrode prepared in the above Example 2 was soaked in 2 mol / L ZnSO4 electrolyte for seven days, with Bare Zn and APS @Zn under the same conditions as control groups The experimental results are shown in Figure 6 X-ray diffraction (XRD) pattern analysis results show that obvious by-product characteristic diffraction peaks appear in the remaining samples except APS-1@Zn, proving that APS-1@Zn can better protect the zinc negative electrode.

[0039] The APS-1@Zn prepared in the above Example 2 and copper foil were assembled into an asymmetric button cell (electrolyte was 2 mol / L ZnSO4), and other conditions were kept the same, and the copper foil and zinc foil were used to form an asymmetric button cell as a control group. Cycle test was performed.

[0040] The experimental results are shown in Figure 7 The results show that the APS-1@Zn / / copper foil asymmetric battery can be stably cycled for more than 750 cycles at a current density of 2 mA·cm -2 The results show that the APS-1@Zn / / copper foil asymmetric battery can be stably cycled for more than 750 cycles at a current density of 2 mA·cm

[0041] The APS-1@Zn prepared in the above Example 2 and zinc foil were assembled into a symmetric button cell (electrolyte was 2 mol / L ZnSO4), and cycle test was performed by using a blue cell test system, then the battery was disassembled, and the cycled electrode was washed with deionized water and ethanol and dried.

[0042] The cycled APS-1@Zn and the electrode with the surface protective layer removed were detected by scanning electron microscopy (SEM), as shown in Figure 8 The zinc was uniformly and densely deposited under the APS-1 layer guided by the three-dimensional protective layer.

[0043] The APS-1@Zn electrode and the iodine-loaded carbon cloth were assembled into a zinc-iodine button cell (electrolyte was 2 mol / L ZnSO4), and CV test was performed by using an electrochemical workstation.

[0044] The test results are shown in Figure 9 An obvious pair of redox peaks corresponding to the typical two-electron redox reaction between I2 and ZnI2 confirmed the expected electrochemical behavior of the full cell.

[0045] The APS-1@Zn electrode and the iodine-loaded carbon cloth were assembled into a zinc-iodine button cell (electrolyte was 2 mol / L ZnSO4), and other conditions were kept the same, and the zinc foil and the iodine-loaded carbon cloth were used to form a zinc-iodine button cell as a control group. Rate and long cycle test were performed by using a blue system.

[0046] The results of the tests are shown in Figure 10 Figure 6, where the coulombic efficiency of the full cell was almost 100% throughout both rate and long cycle tests, indicating the high reversibility of the charge-discharge process. The battery exhibited specific discharge capacities of 201, 184, 155 and 132 mAh g -1 at 1, 2, 5 and 10 C current densities, respectively. In comparison, the battery with Bare Zn anode exhibited a significantly lower capacity of only 110 mAh g -1 at 10 C, further highlighting the superior rate performance of the APS-1@Zn electrode. The cycle stability and representative charge-discharge curves of Zn-I2full batteries with APS-1@Zn and Bare Zn electrodes were further compared, both of which were operated at a current density of 1 A g -1 After an initial activation period, the battery based on APS-1@Zn exhibited a very stable voltage profile and significantly improved long-term cycling performance. Specifically, it exhibited an initial specific capacity of 207 mAh g -1 at 1 C, exceeding the 183 mAh g -1 achieved by the Bare Zn battery. Notably, the APS-1@Zn battery maintained a high capacity of 177 mAh g -1 after 5000 cycles, while the Bare Zn-based battery exhibited rapid capacity decay and completely failed after 1400 cycles. The above not covered by the prior art.

[0047] Although some specific embodiments of the present application have been described in detail by way of example with reference to the drawings, it is to be understood that the examples are for illustrative purposes only and are not intended to limit the scope of the application. Those skilled in the art should understand that various modifications, substitutions, improvements, etc. can be made to the specific embodiments described above without departing from the spirit of the present application or exceeding the scope of the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments in accordance with the technical essence of the present application should be included in the protection scope of the present application.

Claims

1. A zinc anode with a self-assembled protective layer of modified polystyrene microspheres, characterized in that, The zinc foil and the amino-polystyrene microspheres self-assembled in situ on the zinc foil by horizontal evaporation.

2. The zinc anode with a self-assembled protective layer of modified polystyrene microspheres according to claim 1, characterized in that, The amount of amino-functionalized polystyrene microspheres assembled on the zinc foil was 0.0053-0.0106 mg / mm 2 .

3. The zinc anode with a self-assembled protective layer of modified polystyrene microspheres according to claim 1, characterized in that, The amino-polystyrene microspheres are prepared by stirring acrylamide with polystyrene emulsion, centrifugal sedimentation, washing and drying.

4. The zinc anode with a self-assembled protective layer of modified polystyrene microspheres according to claim 3, characterized in that, The mass ratio of polystyrene microspheres to water in the polystyrene emulsion is 1-3:97-99, and the mass ratio of acrylamide to polystyrene microspheres is 1:3-4.

5. The zinc anode with a self-assembled protective layer of modified polystyrene microspheres according to claim 3, characterized in that, The particle size of the polystyrene microspheres is 50nm-700nm.

6. The zinc anode with a self-assembled protective layer of modified polystyrene microspheres according to claim 3, characterized in that, The particle size of the polystyrene microspheres is 50nm, 100nm, 300nm or 700nm.

7. A method for preparing a zinc anode with a self-assembled protective layer of modified polystyrene microspheres according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: The zinc foil is washed in water and ethanol under ultrasonic wave and then dried; The amino-polystyrene microspheres are prepared and dispersed in ethanol to obtain a modified polystyrene microsphere solution; The modified polystyrene microsphere solution is slowly added dropwise on the surface of the zinc foil and left to self-assemble.

8. The production method according to claim 7, wherein The concentration of the modified polystyrene microsphere solution is 1-2wt%.

9. The production method according to claim 7, wherein The self-assembly is left at 50-70℃ for 4-6 minutes.

10. An aqueous zinc-ion battery, characterized in that, The zinc negative electrode with the self-assembled protective layer of modified polystyrene microspheres according to any one of claims 1-6.

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