Three-dimensional ordered macroporous metal oxide air electrode, preparation method thereof and zinc-air battery

Abstract

The application provides a self-supporting three-dimensional ordered macroporous metal oxide air electrode and a preparation method and zinc-air battery application thereof, and belongs to the field of zinc-air batteries and nanomaterial preparation. The microstructure of three-dimensional ordered macropores is constructed, the mass transfer capacity of the metal oxide air electrode is improved, the high porosity can provide efficient transmission channels for the rapid transmission of gas and liquid, the high specific surface area can provide a gas-liquid-solid three-phase reaction area, the number of effective catalytic active sites is increased, the electron transfer is promoted, and a long-life and high-performance zinc-air battery can be realized. The preparation of the three-dimensional ordered macroporous metal oxide air electrode is easy to realize, is universal, and the process is simple. The preparation method is suitable for preparing different materials, and the structural material has important application prospects in the fields of metal-air batteries, fuel cells and water electrolysis.

Description

Technical Field

[0001] This invention belongs to the field of zinc-air batteries and nanomaterial preparation, specifically relating to a self-supporting three-dimensional ordered macroporous metal oxide air electrode, its preparation method, and its application in zinc-air batteries. Background Technology

[0002] Due to the excessive consumption of fossil fuels and the effects of the greenhouse effect and environmental pollution, there is an urgent need to develop efficient and low-cost new energy systems. Zinc-air batteries use aqueous electrolytes, offering high safety with no risk of spontaneous combustion. They also boast high energy density, long lifespan, strong environmental adaptability, high elemental abundance, low cost, easy recycling, and are environmentally friendly. As a green and low-carbon new energy system with broad application prospects, they have become a current research hotspot.

[0003] Currently, the energy density, energy efficiency, and service life of zinc-air batteries are mainly constrained by the charge-discharge processes on the air cathode side, namely the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The low catalytic activity and stability of the cathode electrocatalyst in ORR / OER significantly affect the power density, energy efficiency, and cycle life of zinc-air batteries in practical applications. Transition metal oxides possess excellent intrinsic ORR / OER electrocatalytic performance, high charge transfer rates, and good stability in alkaline media. They are also low-cost and easy to prepare, making them ideal ORR / OER electrocatalysts. The ORR / OER reaction in zinc-air batteries involves a gas-liquid-solid three-phase interface, and the porosity structure of the air electrode has a significant impact on mass transfer efficiency and battery performance. The three-dimensional ordered macroporous (3DOM) structure possesses excellent mass transfer capabilities. Its high porosity provides efficient transport channels for rapid gas-liquid transport; its high specific surface area provides a gas-liquid-solid three-phase reaction region, increasing the number of effective catalytic active sites and promoting electron transfer.

[0004] Therefore, developing three-dimensional ordered macroporous metal oxide air electrodes has significant application value for improving the performance of zinc-air batteries. The preparation method of 3DOM metal oxides mainly involves the colloidal microsphere hard template method. However, during the self-assembly process of the colloidal microsphere opal template and the infiltration process of the precursor solution, tensile stress and capillary forces caused by solvent evaporation and drying or subsequent calcination often lead to large-scale structural defects and cracks, which severely hinder electron transfer and cause battery performance loss. Furthermore, current air electrodes based on 3DOM metal oxides are mainly prepared by synthesizing three-dimensional macroporous metal oxide catalyst powders, using membrane electrodes prepared with the assistance of binders and conductive additives. These methods suffer from bottlenecks such as poor mechanical stability and easy blockage of catalytic active sites. Summary of the Invention

[0005] This invention is made to solve the above-mentioned problems, and aims to provide a self-supporting, binder-free, three-dimensional ordered macroporous metal oxide air electrode, its preparation method, and its application in zinc-air batteries.

[0006] This invention provides a general method for preparing a three-dimensional ordered macroporous metal oxide air electrode, characterized by the following steps: S10, using an ordered stacked opal structure of microspheres supported on a substrate as a template, wherein the microspheres include any one or more of polymethyl methacrylate microspheres, polystyrene microspheres, silica microspheres, polylactic acid microspheres, or chitosan microspheres; S20, immersing the template in a precursor solution containing metal ions and a chelating agent to obtain an intermediate product, wherein the chelating agent includes any one or more of monosaccharides, disaccharides, or polysaccharides; S30, separating, drying, and calcining the intermediate product to obtain the substrate-supported three-dimensional ordered macroporous metal oxide air electrode.

[0007] The method for preparing a three-dimensional ordered macroporous metal oxide air electrode provided by the present invention may also have the following feature: in step S10, the microspheres are of uniform size.

[0008] The method for preparing a three-dimensional ordered macroporous metal oxide air electrode provided by the present invention may also have the following feature: in step S10, the substrate includes any one or more of carbon cloth, stainless steel mesh, copper mesh, nickel mesh, FTO glass, ITO glass, Ti sheet or Si sheet.

[0009] The method for preparing a three-dimensional ordered macroporous metal oxide air electrode provided by the present invention may also have the following features: in step S20, the metal corresponding to the metal ion includes any one or more of Mn, Fe, Zn, Co, Ru, Mo, Al, W, Ni or Ti, the chelating agent includes sucrose and / or glucose, and the solvent of the precursor solution includes any one or more of deionized water, ethanol or methanol.

[0010] The method for preparing a three-dimensional ordered macroporous metal oxide air electrode provided by the present invention may also have the following characteristics: wherein, in the precursor solution of step S20, the concentration of metal ions is 0.5 mol / L to 1 mol / L, and the concentration of chelating agent is 0.05 mol / L to 0.1 mol / L.

[0011] The method for preparing a three-dimensional ordered macroporous metal oxide air electrode provided by the present invention may also have the following feature: in step S20, the template immersion time is 10 min to 30 min.

[0012] The method for preparing a three-dimensional ordered macroporous metal oxide air electrode provided by the present invention may also have the following features: in step S30, the drying method is heating at 70℃~100℃ for 2h~5h, and the calcination method is heating to 400℃~500℃ in a tube furnace under an air atmosphere at a heating rate of 2℃ / min~10℃ / min and calcining for 2h.

[0013] The present invention also provides a three-dimensional ordered macroporous metal oxide air electrode, which is characterized by being prepared by any of the aforementioned methods for preparing a three-dimensional ordered macroporous metal oxide air electrode.

[0014] The three-dimensional ordered macroporous metal oxide air electrode provided by the present invention may also have the following feature: wherein the three-dimensional ordered macroporous metal oxide air electrode is an air electrode without binder.

[0015] The present invention also provides a rechargeable zinc-air battery application, characterized by comprising: an electrolyte comprising an alkaline electrolyte and additives, the alkaline electrolyte comprising NaOH(aq) and / or KOH(aq), and additives comprising zinc acetate(aq) and vanillin(aq); an air cathode being the aforementioned three-dimensional ordered macroporous metal oxide air electrode; and a zinc anode disposed opposite to the air cathode and separated from it by a membrane.

[0016] The role and effect of the invention:

[0017] This invention provides a general method for preparing a self-supporting three-dimensional ordered macroporous metal oxide air electrode. This method is applicable to the preparation of various materials, and this structural material shows significant application prospects in metal-air batteries, fuel cells, and water electrolysis. The preparation method is universal and the process is simple.

[0018] This invention improves the mass transfer capability of a metal oxide air electrode by constructing a three-dimensional ordered macroporous microstructure. The high porosity provides an efficient transport channel for rapid gas-liquid transport, while the high specific surface area provides a gas-liquid-solid three-phase reaction region, increasing the number of effective catalytic active sites and promoting electron transfer, thus enabling a long-life, high-performance zinc-air battery. This invention facilitates the fabrication of a three-dimensional ordered macroporous metal oxide air electrode. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation method of a three-dimensional ordered macroporous metal oxide air electrode according to an embodiment of the present invention.

[0020] Figure 2 These are electron microscope images of polystyrene microsphere templates according to embodiments of the present invention.

[0021] Figure 3 This is a cross-sectional electron microscope image of a polystyrene microsphere template according to an embodiment of the present invention.

[0022] Figure 4 This is an electron microscope image of the three-dimensional ordered macroporous structure Fe2O3 during the preparation process of electrode 1 in an embodiment of the present invention.

[0023] Figure 5 The three-dimensional ordered macroporous structure RuCoO in the electrode 2 fabrication process of this embodiment of the invention. x Electron microscope images.

[0024] Figure 6 The three-dimensional ordered macroporous structure WCoFeNiZnMnRuO is shown in the electrode 3 fabrication process of this embodiment of the invention. x Electron microscope images.

[0025] Figure 7 This is the bifunctional LSV curve of electrode 2 in an embodiment of the present invention.

[0026] Figure 8 These are the charge / discharge polarization curves and power density curves of a zinc-air battery according to an embodiment of the present invention.

[0027] Figure 9 The zinc-air battery of this invention is at 5 mA / cm 2 The discharge specific capacity curve is shown below.

[0028] Figure 10 The zinc-air battery of this invention is at 5 mA / cm 2 The constant current charge-discharge cycle curve is shown below.

[0029] Figure 11 The zinc-air battery of this invention is at 5 / 50 mA / cm 2 The fast charging cycle curve below. Detailed Implementation

[0030] To make the technical means, creative features, objectives and effects of the present invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate a three-dimensional ordered macroporous metal oxide air electrode, its preparation method, and a zinc-air battery.

[0031] Example

[0032] Figure 1 This is a flowchart illustrating the preparation method of a three-dimensional ordered macroporous metal oxide air electrode according to an embodiment of the present invention.

[0033] like Figure 1As shown, this embodiment provides a method for preparing a three-dimensional ordered macroporous metal oxide air electrode, including the following steps:

[0034] S10 uses an opal structure made of carbon cloth-supported polystyrene microspheres as a template.

[0035] The template preparation method includes the following steps:

[0036] S11, add 1500 μL of a 10 wt% scale-uniform polystyrene suspension to 5 mL of deionized water, then add 100 μL of ethylene glycol, and sonicate for 15 min to form a polystyrene microsphere suspension.

[0037] S12, under conditions of 65℃ and 70% humidity, carbon cloth was immersed in a polystyrene microsphere suspension and kept at that temperature for 720 min, and a template of opal structure with carbon cloth loaded with polystyrene microspheres was obtained through self-assembly.

[0038] Figure 2 These are electron microscope images of polystyrene microsphere templates according to embodiments of the present invention; Figure 3 This is a cross-sectional electron microscope image of a polystyrene microsphere template according to an embodiment of the present invention.

[0039] like Figure 2 and Figure 3 As shown, the polystyrene microsphere template prepared by this invention exhibits a hexagonal close-packed state, is uniformly and orderly arranged over a large area, and has no large cracks or defects, with a thickness of up to 35.18 μm.

[0040] S20, immersing the template in a precursor solution containing metal ions and a chelating agent to obtain an intermediate product, includes the following sub-steps:

[0041] S21, add metal ions and chelating agents to a solvent and mix them evenly by magnetic stirring. The metal ions include any one or more of Mn, Fe, Zn, Co, Ru, Mo, Al, W, Ni or Ti, with a concentration of 0.5 mol / L to 1 mol / L. The chelating agents include sucrose and / or glucose, with a concentration of 0.05 mol / L to 0.1 mol / L. The solvent includes any one or more of deionized water, ethanol or methanol.

[0042] S22, add concentrated sulfuric acid to adjust the pH, stir for 2 minutes to obtain the precursor solution.

[0043] S23, the template is soaked in the precursor solution for 15 min to obtain the intermediate product.

[0044] S30, after separating and drying the intermediate product, calcination is performed to obtain a three-dimensional macroporous metal oxide, including the following sub-steps:

[0045] S31. After separating the intermediate product, dry it at 70°C for 30 min.

[0046] S32, the dried intermediate product was calcined at 100℃ for 5h in air atmosphere, and then calcined at 400℃ for 2h, with a heating rate of 2℃ / min, to obtain a three-dimensional ordered macroporous metal oxide air electrode supported on carbon cloth.

[0047] This embodiment also provides a three-dimensional ordered macroporous metal oxide air electrode, which is prepared according to the above steps, and consists of three parts, which are respectively referred to as electrode 1, electrode 2 and electrode 3.

[0048] The specific parameters of electrode 1, electrode 2 and electrode 3 during the preparation process are shown in Table 1.

[0049] Table 1 (Specific parameters of electrode 1, electrode 2 and electrode 3 during the preparation process)

[0050]

[0051] Figure 4 These are electron microscope images of the three-dimensional ordered macroporous structure Fe2O3 during the preparation process of electrode 1 in an embodiment of the present invention. Figure 5 The three-dimensional ordered macroporous structure RuCoO in the electrode 2 fabrication process of this embodiment of the invention. x Electron microscope images; Figure 6 The three-dimensional ordered macroporous structure WCoFeNiZnMnRuO is shown in the electrode 3 fabrication process of this embodiment of the invention. x Electron microscope images.

[0052] like Figures 4-6 As shown, the Fe2O3 (electrode 1) and RuCoO prepared in this embodiment... x (Electrode 2), WCoFeNiZnMnRuO x (Electrode 3) all exhibit a high-quality three-dimensional ordered macroporous structure over a large area. The channels are uniform and ordered, basically avoiding defects and cracks. A three-dimensional long-range ordered multi-layered pore interconnection structure can be observed.

[0053] Figure 7 This is the bifunctional LSV curve of electrode 2 in an embodiment of the present invention.

[0054] like Figure 7 As shown, electrode 2 in this embodiment (three-dimensional ordered macroporous structure RuCoO) x The air electrode exhibits excellent bifunctional oxygen electrocatalytic activity, with an oxygen evolution reaction overpotential as low as 192 mV (E0). 10 =1.422V) and the high half-wave potential of the oxygen reduction reaction: E 1 / 2=0.824V, making the potential difference (ΔE=E) 10 -E 1 / 2 As low as 0.598V.

[0055] This embodiment also provides a zinc-air battery, which uses electrode 2 (a three-dimensional ordered macroporous structure RuCoO) from this embodiment. x It serves as the air cathode.

[0056] The zinc-air battery in this embodiment includes a zinc anode, an air cathode, a separator, and an electrolyte.

[0057] The zinc anode (zinc foil) and the air cathode (electrode 2 in this embodiment) are arranged opposite each other and separated by a diaphragm.

[0058] The electrolyte includes an alkaline electrolyte and additives. The alkaline electrolyte includes NaOH (aq) and / or KOH (aq), and the additives include zinc acetate (aq) and vanillin (aq).

[0059] Figure 8 These are the charge / discharge polarization curves and power density curves of a zinc-air battery according to an embodiment of the present invention.

[0060] like Figure 8 As shown, during the discharge process, based on the three-dimensional ordered macroporous RuCoO x Zinc-air batteries (RuCoO) x The peak power density of the base cell is 215 mW / cm². 2 Superior to Pt / C+RuO2 (188.7mW / cm) 2 ).

[0061] Figure 9 The zinc-air battery of this embodiment of the invention operates at 5 mA / cm². 2 The discharge specific capacity curve is shown below.

[0062] like Figure 9 As shown, RuCoO x The base cell is at 5mA / cm 2 The specific capacity is 694.77mAh / g. Zn It can be continuously and stably discharged at 1.2V for 125 hours. RuCoO x The specific capacity of the base battery has reached the same level as Pt / C+RuO2 (700.3mAh / g). Zn (A comparable level, showing RuCoO) x The water-based zinc-air battery exhibits excellent discharge stability.

[0063] Figure 10 The zinc-air battery of this invention is at 5 mA / cm 2Constant current charge-discharge cycle curves under these conditions; Figure 11 The zinc-air battery of this invention is at 5 / 50 mA / cm 2 The fast charging cycle curve below.

[0064] like Figure 10 and 11 As shown, RuCoO x The base battery exhibits excellent charge-discharge performance and cycle stability, with a very small charge-discharge voltage difference after long-term operation. At 5mA / cm 2 During low discharge, the charge-discharge energy efficiency reaches 69.50%, and the service life exceeds 590 hours, which is significantly better than Pt / C+RuO2. Fast charging cycles can even stably reach 1380 hours at a charging potential of only 2.48V, with almost no efficiency degradation after prolonged charge-discharge cycles.

[0065] The role and effects of the embodiments:

[0066] This embodiment describes a method for preparing a self-supporting three-dimensional ordered macroporous metal oxide air electrode. The method uses an ordered stacked opal structure of microspheres supported on a substrate as a template. The opal template is immersed in a precursor solution containing metal ions and a chelating agent. The chelating agent chelates the metal ions in the precursor solution, ensuring uniform wetting within the template. During calcination, the chelating agent optimizes the oxidation temperature of the metal precursor and the decomposition temperature of the template, allowing the formation of a stable metal oxide network before template collapse, thus guaranteeing a perfect three-dimensional macroporous structure. Utilizing the confinement effect of the chelating agent and the microsphere template, a large-area, uniform, crack-free three-dimensional ordered macroporous metal oxide can be obtained after low-temperature calcination. This invention is simple to operate, has broad applicability, and can be used to prepare more than 20 types of unary and multi-element three-dimensional ordered macroporous metal oxide air electrodes. This air electrode has broad application potential in the field of zinc-air batteries.

[0067] In this embodiment, the chelating agent chelates the metal ions in the precursor solution, allowing them to be uniformly impregnated and dispersed in the template, effectively preventing the agglomeration of metal particles.

[0068] In this embodiment, during the calcination process, the chelating agent optimizes the oxidation temperature of the metal precursor and the decomposition temperature of the template, which can form a stable metal oxide network before the template collapses, ensuring a perfect three-dimensional macroporous structure.

[0069] The chelating agent in this embodiment can be used as a secondary template agent for the generation of mesopores, providing greater porosity and higher specific surface area.

[0070] The three-dimensional ordered macroporous structure of the metal oxide air electrode in this embodiment can achieve rapid mass transfer and fully expose effective catalytic active sites, thus achieving excellent ORR / OER catalytic performance.

[0071] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a three-dimensional ordered macroporous metal oxide air electrode, characterized by, The method comprises the following steps: S11, 1500 μL of 10 wt% polystyrene suspension with uniform size is added into 5 mL of deionized water, 100 μL of ethylene glycol is added, and ultrasonic treatment is performed for 15 min to form a polystyrene microsphere suspension; S12, the carbon cloth is immersed in the polystyrene microsphere suspension at 65°C and under a humidity of 70% for 720 min to self-assemble a polystyrene microsphere-accumulated opal structure template loaded on the carbon cloth, wherein the template is uniformly and orderly arranged, the template has no large cracks or defects, and the thickness of the template is 35.18 μm; S20, the template is immersed in a precursor solution containing metal ions and a chelating agent and adjusted by concentrated sulfuric acid to obtain an intermediate product; S30, the intermediate product is separated and dried, and then heated to 400-500°C at a heating rate of 2-10°C / min in a tube furnace under an air atmosphere and calcined for 2 h to obtain a three-dimensionally ordered macroporous metal oxide air electrode loaded on the carbon cloth, The three-dimensionally ordered macroporous metal oxide air electrode is used as an air electrode without binder, When the salt corresponding to the metal ions in step S20 is 1 mmol of ruthenium chloride and 1 mmol of cobalt chloride hexahydrate, the chelating agent is 40 mg of sucrose, the precursor solution is 200 μL of deionized water and 1800 μL of ethanol, and the amount of concentrated sulfuric acid is 4 μL, the structure of the three-dimensionally ordered macroporous metal oxide air electrode is RuCoO x , and the oxygen evolution reaction overpotential thereof is as low as 192 mV, and the oxygen reduction reaction high half-wave potential is 0.824 V.

2. The method for preparing the three-dimensionally ordered macroporous metal oxide air electrode according to claim 1, wherein: wherein In step S20, the template is immersed for 10-30 min.

3. The method for preparing the three-dimensionally ordered macroporous metal oxide air electrode according to claim 1, wherein: wherein In step S30, the drying method is heating at 70-100°C for 2-5 h.

4. A three-dimensional ordered macroporous metal oxide air electrode, characterized in that, The three-dimensionally ordered macroporous metal oxide air electrode is prepared by the method for preparing the three-dimensionally ordered macroporous metal oxide air electrode according to any one of claims 1-3.

5. A zinc-air battery characterized by comprising: It comprises: an electrolyte, which comprises a basic electrolyte and an additive, the basic electrolyte comprises a NaOH solution and / or a KOH solution, and the additive comprises a zinc acetate solution and a vanillin solution; an air cathode, which is the three-dimensionally ordered macroporous metal oxide air electrode according to claim 4; and a zinc anode, which is arranged opposite to the air cathode and is separated from the air cathode by a diaphragm. ​

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