Preparation method and application of SiO2-ZnO heterojunction modified zinc composite foil anode Zn@ZSHJ

Abstract

The invention belongs to the technical field of nanomaterial preparation, and particularly relates to a preparation method and application of a SiO2-ZnO heterojunction modified zinc composite foil anode Zn@ZSHJ. 5 mL of tetraethyl orthosilicate (TEOS) is added dropwise to 40 mL of anhydrous ethanol and stirred for 30 min, and then 120 mL of deionized water is added and stirred for 30 min. The mixed solution and a 100 μm thick zinc foil (4.5 cm×15 cm) are transferred to a 200 mL polytetrafluoroethylene-lined stainless steel autoclave for reaction at 120°C for 36 h. Thereafter, the metal foil is taken out, washed with deionized water, and kept in a tube furnace at 300°C for 12 h. The final product obtained by the treatment is a Zn@ZSHJ anode. The present invention adopts a fusion strategy to prepare a high-performance Zn@ZSHJ composite anode in one step. This preparation method has the advantages of simple process, low cost, and large-scale preparation, and provides a new electrode material for the research and application of long-life anodes of aqueous zinc ion batteries.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation, and in particular relates to a preparation method and application of a SiO2-ZnO heterojunction modified zinc composite foil anode Zn@ZSHJ. Background Art

[0002] The extensive use of fossil fuels has caused serious damage to the environment, and the development of clean energy has received increasing attention. As an intermediate link in the energy storage stage, driven by rapid industrial growth and rising energy demand, exploring stable, efficient and low-cost energy storage systems is crucial to the sustainable development of industry. Although lithium-ion batteries dominate the consumer electronics market due to their outstanding energy density and high voltage platform, their limited and unevenly distributed lithium resources, high preparation requirements, and potential hazards such as the use of flammable organic electrolytes have prompted people to study alternative battery technologies. Aqueous zinc-ion batteries stand out from many candidates due to their considerable economic benefits, high safety and environmentally friendly advantages. Zinc metal has a suitable redox potential (-0.76 V vs. SHE), ultra-high volumetric energy density (5855 mAh cm -3 ), excellent electroplating / stripping reversibility and stability in water, the zinc metal anode can be directly used as the anode of aqueous zinc ion batteries. It is worth noting that the metal anode will release hydrogen, corrode and produce zinc dendrites during long-term cycling. The main reasons are: the electrolyte commonly used in zinc ion batteries is generally weakly acidic. During the long-term charging and discharging process, the zinc metal on the surface of the prototype will inevitably be corroded, leading to hydrogen evolution; and because the surface of the zinc metal anode is not completely flat, due to the "tip effect" during ion deposition, the protruding part is more likely to deposit zinc. Over time, zinc dendrites become more and more obvious, and may eventually pierce the diaphragm and cause the battery to short-circuit. In addition, due to the H in the hydrogen evolution process + The consumption of electrolyte will lead to the increase of local pH of electrolyte and the accumulation of passivation byproducts such as Zn4SO4(OH)6·xH2O, which is also extremely unfavorable to the zinc anode and the long-term operation of aqueous zinc-ion batteries. Anode interface regulation is one of the most common optimization strategies. Summary of the invention

[0003] The purpose of the present invention is to provide a preparation method and application of a SiO2-ZnO heterojunction modified zinc composite foil anode Zn@ZSHJ. The present invention adopts a hydrothermal-calcination fusion strategy for preparation, has a simple process, low cost, can be prepared on a large scale, has good electrochemical energy storage performance, and provides a new type of nanomaterial for the research and application of electrode materials for aqueous zinc ion batteries.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for preparing a SiO2-ZnO heterojunction modified zinc composite foil anode Zn@ZSHJ comprises the following steps:

[0006] S1. Add tetraethyl orthosilicate dropwise into anhydrous ethanol and stir for 30 to 60 min at a speed of 500 to 2000 rpm, wherein the volume ratio of tetraethyl orthosilicate to anhydrous ethanol is 1:8;

[0007] S2. Add deionized water to the solution obtained in step S1 and continue stirring for 30 to 60 min at a speed of 500 to 1000 rpm;

[0008] S3. The solution obtained in step S2 is transferred to a hydrothermal kettle and a piece of zinc foil is added, and then placed in a drying oven at 120-180°C for 12-36 h;

[0009] S4. The material prepared in step S3 is placed in a tubular furnace and kept at 250-300° C. for 6-24 h to obtain a zinc composite foil anode Zn@ZSHJ.

[0010] Furthermore, in step S2, the volume ratio of deionized water to anhydrous ethanol is 3:1.

[0011] A zinc composite foil anode Zn@ZSHJ prepared by the preparation method.

[0012] Energy storage application of a zinc composite foil anode Zn@ZSHJ in aqueous zinc ion battery anode.

[0013] The invention has the advantages that: the invention synthesizes a SiO2-ZnO heterojunction modified zinc metal composite foil Zn@ZSHJ for the anode of aqueous zinc ion battery by a hydrothermal-calcination fusion strategy method, the calcination is more to stabilize the interface structure, and remove excess impurities from the interface during the calcination process; the hydrophilic SiO2 layer is conducive to the desolvation process of hydrated zinc ions to reduce the zinc atom nucleation barrier, and the solid ZnO layer regulates the electric field distribution on the zinc surface to induce uniform zinc nucleation. The new SiO2-ZnO heterojunction (ZSHJ) interface phase with combing induction effect can provide a dual protection mechanism for the zinc metal anode. Therefore, the zinc metal composite foil Zn@ZSHJ modified by SiO2-ZnO heterojunction can effectively inhibit the generation of zinc dendrites and hydrogen evolution in the anode of aqueous zinc ion battery, so as to promote the large-scale application in the fields of aqueous zinc ion battery and the like. The preparation method has the advantages of simple process, low cost, environmental friendliness, strong repeatability, large-scale preparation and good long-term stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1This is the working mechanism of the SiO2-ZnO heterojunction modified zinc metal composite foil Zn@ZSHJ anode of the present invention.

[0015] Figure 2 2 is the XRD pattern of pure Zn and Zn@ZSHJ in the examples of the present invention.

[0016] Figure 3 This is a SEM image of the pure Zn surface in the embodiment of the present invention.

[0017] Figure 4 This is a SEM image of the surface of Zn@ZSHJ in an embodiment of the present invention.

[0018] Figure 5 The XRD patterns of pure Zn and Zn@ZSHJ in the embodiment of the present invention after being immersed in 2M ZnSO4 electrolyte solution for 15 days.

[0019] Figure 6 This is a surface SEM image of pure Zn in an embodiment of the present invention after being immersed in a 2M ZnSO4 electrolyte solution for 15 days.

[0020] Figure 7 This is the surface SEM image of Zn@ZSHJ in the embodiment of the present invention after being immersed in 2M ZnSO4 electrolyte solution for 15 days.

[0021] Figure 8 It is the Tafel curve of pure Zn and Zn@ZSHJ in 2M ZnSO4 electrolyte solution in the embodiment of the present invention.

[0022] Fig. 9 LSV curves of pure Zn and Zn@ZSHJ in 2M Na2SO4 electrolyte solution in the examples of the present invention.

[0023] Fig.10 The Zn||Zn and Zn@ZSHJ||Zn@ZSHJ symmetric cells in the embodiment of the present invention are shown in Figure 2 at 1 mA cm -2 The current density and 1 mAh cm -2 Electrochemical tests at capacitance density of .

[0024] Fig.11 The Zn||MnO2 and Zn@ZSHJ||MnO2 full cells in the embodiment of the present invention are shown in Figure 2 at 0.1 mV s -1 Cyclic voltammetry test at a scan rate of .

[0025] Fig.12 This is the AC impedance test of the Zn||MnO2 and Zn@ZSHJ||MnO2 full batteries in the embodiments of the present invention.

[0026] Fig.13This is the rate performance test of the Zn||MnO2 and Zn@ZSHJ||MnO2 full batteries in the embodiments of the present invention.

[0027] Fig.14 The Zn||MnO2 and Zn@ZSHJ||MnO2 full cells in the embodiment of the present invention are shown in Figure 2 at 1 A g -1 Long cycle test at current density of 2.5 Å.

[0028] Fig.15 The adsorption structures of H2O molecules on Zn, ZnO and SiO2 in the embodiments of the present invention are calculated based on density functional theory (DFT).

[0029] Fig.16 is the adsorption energy of H2O molecules on different crystal planes of Zn, ZnO and SiO2 in the embodiment of the present invention. DETAILED DESCRIPTION Example

[0030] A method for preparing a SiO2-ZnO heterojunction modified zinc metal composite foil anode Zn@ZSHJ is as follows:

[0031] (1) First, add 5 mL of tetraethyl orthosilicate (TEOS) dropwise into 40 mL of anhydrous ethanol and stir for 30 min;

[0032] (2) Add 120 mL of deionized water to the solution obtained in step (1) under low-speed magnetic stirring and continue stirring for 30 minutes;

[0033] (3) The solution obtained in step (2) was transferred to a hydrothermal reactor and a piece of 100 μm thick commercial zinc foil (4.5 cm × 15 cm) was placed in the reactor, and then placed in a drying oven at 120 °C for 36 h;

[0034] (4) Then, the sample obtained in step (3) was placed in a tube furnace and kept at 300°C in air for 12 h to obtain the final zinc composite foil Zn@ZSHJ.

[0035] The SEM and XRD patterns of the prepared products are shown in Figure 2-7 The electrochemical energy storage performance is shown in Figure 8-14 shown.

[0036] Performance Testing

[0037] The obtained SiO2-ZnO heterojunction modified zinc metal composite foil Zn@ZSHJ was cut into metal discs with a diameter of 12 mm as battery anodes. In the electrolyte immersion test of 2 M ZnSO4, Zn@ZSHJ has an excellent corrosion inhibition effect ( Figure 5-8 ), Figure 5-8Corresponding to the corrosion resistance comparison of the two zinc anodes in 2M ZnSO4, many byproducts appeared on the pure Zn surface after two weeks. The PDF card corresponds to the generation of Zn4SO4(OH)6·xH2O passivation byproducts, which not only affect the conductivity of the electrode surface, but also have a significant adverse effect on the orderly deposition of zinc ions; Figure 8 It is a comparison of Tafel curves of symmetrical cells based on two anodes. A more positive potential corresponds to a stronger corrosion resistance. In addition, Fig. 9 The LSV test curves of the two anodes in 1M NaSO4 solution. The smaller current density represents a better ability to inhibit hydrogen evolution. Zn@ZSHJ exhibits a better ability to inhibit hydrogen evolution than pure Zn ( Fig. 9 ). Electrochemical tests were performed on button cells assembled with 2 M ZnSO4 as the electrolyte. The Zn-Zn symmetric battery assembled based on Zn@ZSHJ also showed a better cycle life than pure Zn ( Fig.10 ), the symmetric battery of the two anodes was cycled for a long time to simulate the deposition-plating process of the battery, and the modified zinc anode had a significantly better cycle life; Figure 11-14 For the comparison of full batteries based on two anodes and MnO2 cathode, the zinc ion full battery based on Zn@ZSHJ anode has a more stable operating voltage range, smaller charge transfer resistance, and better rate performance. It also has smaller capacity decay during long-cycle cycles. The full battery assembled based on Zn@ZSHJ anode and MnO2 cathode also has more outstanding rate performance and service life ( Figures 11 to 14 ), Figure 15-16 The results are a comparison of the adsorption energies of water molecules on different crystal planes of Zn, ZnO, and SiO2. The calculation results show that the insulating ZnO and SiO2 crystal planes have a stronger adsorption effect on water molecules, which helps the desolvation process of hydrated zinc ions and is more conducive to the efficient deposition behavior of zinc ions. Fig.15 as well as Fig.16 The ZSHJ structure reveals the effect of Zn 2+ The insulating ZSHJ not only isolates the Zn anode from the contact with the H2O molecules in the solution to reduce corrosion. In addition, the stronger adsorption capacity of the ZnO and SiO2 interface for H2O molecules helps the desolvation process of hydrated zinc ions during the deposition process, reducing the Zn 2+ The nucleation barrier facilitates a more stable deposition behavior.

Claims

1. A method for preparing a SiO2-ZnO heterojunction modified zinc composite foil anode Zn@ZSHJ, characterized in that: The following steps are involved: S1. Add tetraethyl orthosilicate dropwise into anhydrous ethanol and stir for 30 to 60 min, wherein the volume ratio of tetraethyl orthosilicate to anhydrous ethanol is 1:8; S2. Add deionized water to the solution obtained in step S1 and continue stirring for 30 to 60 min; S3. The solution obtained in step S2 is transferred to a hydrothermal kettle and a piece of zinc foil is added, and then placed in a drying oven at 120-180°C for 12-36 h; S4. The material prepared in step S3 is placed in a tubular furnace and kept at 250-300° C. for 6-24 h to obtain a zinc composite foil anode Zn@ZSHJ.

2. The method for preparing the SiO2-ZnO heterojunction modified zinc composite foil anode Zn@ZSHJ according to claim 1, characterized in that: The volume ratio of deionized water to anhydrous ethanol in step S2 is 3:

1.

3. The zinc composite foil anode Zn@ZSHJ prepared by the preparation method according to claim 1 or 2.

4. Energy storage application of the zinc composite foil anode Zn@ZSHJ as claimed in claim 3 in aqueous zinc ion battery anode.

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