CN114614027A - Preparation method of CoFe-S @3D-S-NCNT electrode and quasi-solid zinc-air battery - Google Patents

Abstract

Preparation method of CoFe-S@3D-S-NCNT electrode and quasi-solid-state zinc-air battery. The invention relates to the technical field of rechargeable quasi-solid-state zinc-air batteries, in particular to a preparation method of an electrode and a quasi-solid-state zinc-air battery comprising the electrode. By using cobalt salt, iron salt and 2-methylimidazole as reaction raw materials, CoFe-MOF nanosheets were grown at room temperature and then carbonized by CVD annealing to obtain CoFe@3D-NCNT micro-nano materials; then hydrothermally in sodium sulfide solution reaction to obtain CoFe-S@3D-S-NCNT micro-nano composites with 3D micro-nano hierarchical structure, high catalytic activity and good hydrophobicity. The as-prepared CoFe‑S@3D‑S‑NCNT composite was used as a cathode, which was assembled with a zinc anode and a quasi-solid electrolyte to form a quasi-solid-state zinc-air battery with a sandwich structure. The battery has ideal charge-discharge performance, the open circuit voltage is as high as 1.479V, the discharge peak power density is as high as 460mW/cm ² , it has excellent charge-discharge stability, and can be cycled for more than 225 cycles.

Description

Preparation method of CoFe-S@3D-S-NCNT electrode and quasi-solid-state zinc-air battery

technical field

The invention relates to the technical field of preparation of quasi-solid rechargeable zinc-air batteries, and the air cathode side specifically relates to the technical field of preparation of new energy materials.

Background technique

Quasi-solid-state zinc-air batteries have the advantages of high energy density, portability, small size, low cost, safety, and environmental protection, and have good application prospects. However, the low peak power density and poor stability of quasi-solid-state Zn-air batteries remain a huge challenge for practical applications. As the core component of quasi-solid-state zinc-air batteries, the air electrode has an important impact on the energy storage density, discharge peak power density, and cycle life of the battery. Therefore, the development of cathode electrocatalytic materials and air electrodes with high catalytic activity, high stability, and high reaction kinetics is of great significance to promote the practical application of high-performance quasi-solid-state zinc-air batteries, and will also produce significant economic and social benefits. . The current development of wearable electronic devices has attracted much attention to quasi-solid-state zinc-air batteries, which require the battery to maintain high performance while being portable. Therefore, the design of the battery needs to pay attention to both its electrochemical performance and structural stability.

Platinum-carbon, ruthenium oxide, and iridium oxide are by far the most effective electrocatalysts for ORR and OER. However, such precious metal materials are expensive and also have poor immunity to fuel oxidizing molecules. Moreover, the prepared integrated electrode material cannot have both high bifunctional activity, and the assembled quasi-solid-state zinc-air battery has insufficient performance. Regardless of the challenge, it is important to develop an efficient and durable electrocatalyst. Therefore, the cathode material in the present invention aims to prepare an economical and efficient bifunctional electrocatalyst—the sulfided cobalt-iron alloy nanoparticles are wrapped in nitrogen-doped carbon nanotube materials, wherein cobalt-iron sulfide plays the role of It has the function of catalyzing the oxygen evolution reaction (OER) and the function of nitrogen-doped carbon nanotubes catalyzing the ORR reaction. In addition, the morphology, structure, electrical conductivity and surface component defects of this carbon nanotube structure material can also cooperate with each other to promote the catalytic reaction. conduct. The prepared cathode catalyst, zinc anode and electrolyte form a sandwich-structured quasi-solid-state zinc-air battery. The preparation of powder air electrode materials with high bifunctional activity, high power density, and excellent stability by this facile method has not been reported for quasi-solid-state zinc-air batteries.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention provides a CoFe-S@3D-S-NCNT micro-nano composite material and a preparation method and application thereof. The material has high bifunctional activity, and the quasi-solid-state zinc-air battery with sandwich structure assembled with zinc anode and electrolyte has excellent peak power density and good cycle stability.

One of the technical solutions of the present invention is a CoFe-S@3D-S-NCNT micro-nano composite material, a material with a 3D micro-nano composite structure for in-situ growth of CoFe alloy carbon nanotubes on a three-dimensional carbon substrate. CoFe-S@3D-S-NCN micro-nanocomposite has 3D micro-nano hierarchical structure and good hydrophobicity. Air cathode, zinc anode and quasi-solid electrolyte prepared by CoFe-S@3D-S-NCNT micro-nanocomposite A quasi-solid-state zinc-air battery with a sandwich structure is formed, which exhibits high peak power density and high cycle stability.

The second technical solution of the present invention, the preparation method of the above-mentioned CoFe-S@3D-S-NCNT micro-nano composite material, includes the following steps: using cobalt salt, iron salt and 2-methylimidazole as reaction raw materials to obtain CoFe-MOF After the nanosheets were annealed and carbonized by CVD, CoFe@3D-NCNT micro-nanomaterials were obtained; and then the hydrothermal reaction was carried out in an aqueous sodium sulfide solution to obtain CoFe-S@3D coated with cobalt sulfide and cobalt iron sulfide on the surface of CoFe@3D-NCNT. -S-NCNT micro-nano composites.

Further, the following steps are specifically included:

(1) Preparation of CoFe-MOF nanosheets: the mixed solution composed of cobalt salt, iron salt aqueous solution and 2-methylimidazole aqueous solution is aged, centrifugally washed and dried to obtain CoFe-MOF;

(2) Preparation of CoFe@3D-NCNT: CoFe@3D-NCNT nanomaterials were obtained by annealing CoFe-MOF nanosheets in a mixed hydrogen atmosphere in the presence of melamine;

(3) Preparation of CoFe-S@3D-S-NCNT: CoFe@3D-NCNT nanomaterials were immersed in sodium sulfide solution for hydrothermal reaction, washed and dried to obtain CoFe-S@3D-S-NCNT.

Further, in the step (1), the cobalt salt can be cobalt nitrate, cobalt chloride, cobalt acetate, the concentration of its aqueous solution is 5-20g/L, and the iron salt can be ferric chloride, ferric nitrate, ferric acetate, The concentration of its aqueous solution is 0.5-2g/L, the concentration of 2-methylimidazole aqueous solution is 20-50g/L; the stirring time is 2-6h, the drying temperature is 60°C, and the drying time is 10h.

Further, the step (2) specifically includes: placing the CoFe-MOF nanosheets in the downstream of the tubular atmosphere furnace tube, placing the melamine upstream, and calcining in an argon+hydrogen atmosphere, and then within 0.5 to 2 hours Raise the temperature to 700-900 °C for 1-2 hours, and cool down naturally to obtain CoFe@3D-NCNT;

In the mixed atmosphere of argon and hydrogen, argon is 85-95%, and hydrogen is 5-15%. A preferred solution is that in a mixed atmosphere of argon and hydrogen, 95% argon and 5% hydrogen.

The mass ratio of melamine to cobalt salt and iron salt is 0.05-0.2:5-20:5-20. Under the high temperature atmosphere, the ammonium ions in melamine and a small amount of hydrogen in the atmosphere have reducing properties, which will reduce the metal ions in the CoFe-MOF to metal alloys, and the metal alloys catalyze growth into carbon nanotubes in the presence of carbon sources.

Further, in the step (3): the concentration of the sodium sulfide solution is 10-20g/L; the hydrothermal reaction temperature is 100-140°C, and the hydrothermal reaction time is 6-18h.

The sulfide ions in the sodium sulfide solution can form sulfides with some metal particles in the three-dimensional carbon framework in a hydrothermal environment, and also form sulfides with some alloys in carbon nanotubes, which makes its catalytic performance significantly improved.

The third technical solution of the present invention is the application of the above-mentioned CoFe-S@3D-S-NCNT micro-nano composite material in the air electrode of a quasi-solid zinc-air battery.

The fourth technical solution of the present invention is a quasi-solid-state zinc-air battery air electrode. The above-mentioned CoFe-S@3D-S-NCNT micro-nano composite material is added with ethanol and naphthol solution in a ratio of (800-1000 μL) : (40-100 μL), ultrasonically mixed for 40-80 min to obtain catalyst ink, drop the catalyst ink on carbon paper or carbon cloth, and dry at 50°C to obtain a quasi-solid rechargeable zinc-air battery air electrode.

In the fifth technical solution of the present invention, a quasi-solid-state zinc-air battery anode material is one of in-situ electro-galvanizing, such as zinc flakes, zinc foils, zinc strips, and carbon cloth and carbon paper.

In the sixth technical solution of the present invention, a quasi-solid electrolyte material of a quasi-solid zinc-air battery is one of PVA electrolyte, PaNa electrolyte, biological cellulose membrane electrolyte, and acrylic gel electrolyte.

The seventh technical solution of the present invention is a quasi-solid zinc-air battery, which is made of CoFe-S@3D-S-NCNT nanocomposite carbon paper as a cathode electrode, a zinc anode electrode, and an electrolyte gel to obtain CoFe-S Quasi-solid-state zinc-air batteries of @3D-S-NCNT micro-nanocomposites.

Compared with the prior art, the beneficial effects of the present invention:

The CoFe-S@3D-S-NCNT three-dimensional micro-nano composite material has a composite structure in which carbon nanotubes grow in-situ on a three-dimensional carbon skeleton, and the product has a uniform morphology. This microstructure has a certain degree of hydrophobicity. Good OER performance and excellent ORR performance of carbon nanotubes, the composite material combines the advantages of the three and possesses high bifunctional activity. Due to the increase in hydrophobicity, more air can be contacted in the electrolyte, so that the discharge polarization is significantly improved, and the power density of the material is further improved.

The preparation method of the CoFe-S@3D-S-NCNT three-dimensional micro-nano composite material air electrode according to the present invention has the advantages of high repeatability, simple synthesis process, easy control and the like. The as-prepared CoFe-S@3D-S-NCNT micro-nanocomposite material is used as a quasi-solid-state zinc-air battery composed of a cathode, a zinc anode and a quasi-solid electrolyte material with high bifunctional activity, high power density, and high stability; Applied to the air electrode of rechargeable solid-state zinc-air battery, the power density is 460mWcm ² , and the long-term stability of 225 cycles.

Description of drawings

Fig. 1 is the XRD pattern of the product prepared in Example 1, wherein: the abscissa X is the diffraction angle (2θ), and the ordinate Y is the relative diffraction intensity.

Figure 2 is a TEM image of the product prepared in Example 1, the objects in a picture are Co ₉ S ₈ , Co and amorphous carbon materials, and the objects in b picture are Co ₈ FeS ₈ and Co ₇ Fe ₃ .

FIG. 3 is a topography (5 μm) of the CoFe-S@3D-S-NCNT micro-nanocomposite prepared in Example 1. FIG.

FIG. 4 is a topography (2 μm) of the CoFe-S@3D-S-NCNT micro-nanocomposite prepared in Example 1. FIG.

FIG. 5 is a topography diagram of the CoFe@3D-NCNT material prepared in step (2) in Example 1. FIG.

6 is a hydrophobicity diagram of the CoFe-S@3D-S-NCNT micro-nanocomposite prepared in Example 1.

7 is a graph of the ORR performance of the CoFe-S@3D-S-NCNT micro-nanocomposite prepared in Example 1.

FIG. 8 is a graph showing the OER performance of the CoFe-S@3D-S-NCNT micro-nanocomposite prepared in Example 1.

FIG. 9 is a performance diagram of the ORR stability test of the CoFe-S@3D-S-NCNT micro-nanocomposite prepared in Example 1. FIG.

FIG. 10 is a diagram of the PaNa quasi-solid electrolyte prepared in Example 1. FIG.

11 is an open circuit voltage diagram of a rechargeable zinc-air battery prepared with CoFe-S@3D-S-NCN micro-T nanocomposite in Example 1.

12 is the discharge polarization curve performance results of the rechargeable zinc-air battery of the CoFe-S@3D-S-NCN micro-T nanocomposite prepared in Example 1.

13 is the cycle performance results of the rechargeable zinc-air battery of the CoFe-S@3D-S-NCNT micro-nanocomposite prepared in Example 1.

14 is a diagram of the rechargeable zinc-air battery of the CoFe-S@3D-S-NCNT micro-nano composite prepared in Example 1 lighting up an LED light.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail, which detailed description should not be construed as a limitation of the invention, but rather as a more detailed description of certain aspects, features, and embodiments of the invention.

It should be understood that the terms described in the present invention are only used to describe particular embodiments, and are not used to limit the present invention. Additionally, for numerical ranges in the present disclosure, it should be understood that each intervening value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated value or intervening value in that stated range is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the present invention. The description and examples of the present application are only exemplary.

As used herein, "comprising," "including," "having," "containing," and the like, are open-ended terms, meaning including but not limited to.

Example 1

(1) Preparation of CoFe-MOF

Dissolve 0.582g cobalt nitrate (Co(NO ₃ ) ₂ 6H ₂ O) and 0.06g ferrous chloride tetrahydrate (FeCl ₂ 4H ₂ O) in 40 mL of deionized water, and dissolve 1.32 g 2 -Methylimidazole (2-MIM) was mixed with 40 mL of deionized water, aged at room temperature for 4 hours, the purple solution was washed several times with deionized water and ethanol at 6500 rpm, and dried at 80°C for 12 hours.

(2) Preparation of CoFe@3D-NCNT

The prepared CoFe-MOF purple powder was placed downstream of the porcelain boat, and melamine was placed upstream, and the porcelain boat was placed in a tube furnace for calcination. The calcination atmosphere was 95% argon + 5% hydrogen, and the calcination temperature was 800 °C. The heating time was 176 minutes, and the holding time was 1 hour. After the tube furnace cooled down naturally, the CoFe@3D-NCNT nanomaterials were obtained.

(3) Preparation of CoFe-S@3D-S-NCNT

0.7 g of sodium sulfide was ultrasonically dissolved in 40 mL of deionized water, transferred to a reactor, the CoFe@3D-NCNT black powder synthesized in step (2) was immersed in the solution, hydrothermally reacted at 120 ° C for 10 hours, cooled to room temperature, Centrifugal washing with deionized water and ethanol at 6500 rpm for several times, and drying at 80 °C, the final product CoFe-S@3D-S-NCNT nanocomposite was obtained.

The XRD test results in this example show that: as shown in Figure 1, the abscissa X is the diffraction angle (2θ), the ordinate Y is the relative diffraction intensity, and the diffraction peaks correspond to the C peak, the Co peak, and the peak of the CoFe alloy. . As for the absence of sulfides, it is because the degree of sulfide in the waters is weak, and the detection ability of XRD is limited and cannot be found.

For this example, the TEM test results show that: as shown in Figure 2, Co ₉ S ₈ , Co, amorphous C materials, Co ₇ Fe ₃ and Co ₈ FeS ₈ were found in the TEM, proving that the successful hydrothermal vulcanization makes the alloy transition to sulfide

The nanocomposite prepared in this example is analyzed by field emission scanning electron microscope, and the obtained electron microscope photo is shown in Fig. 3-5; Fig. 3-4 is the prepared CoFe-S@3D-S-NCNT micro-nano composite material Figure 5 shows the morphology of the CoFe@3D-NCNT micro-nano material prepared in step (2); it can be seen that the in-situ growth of carbon nanotubes on the three-dimensional carbon framework Micro-nano composite structure, the CoFe-S@3D-S-NCNT micro-nano composite material prepared in this example has a uniform morphology and a typical hydrophobic structure.

Take the CoFe-S@3D-S-NCNT micro-nano composite material prepared in this example, and after sufficient grinding, add ethanol and naphthol solution in sequence in the ratio of (800-1000 μL): (40-100 μL), and ultrasonically mix 40 ~80min to obtain catalyst ink, drop the catalyst ink on carbon paper or carbon cloth with an area of 1 square centimeter, and dry at 50°C to obtain a quasi-solid rechargeable zinc-air battery air electrode.

The prepared CoFe-S@3D-S-NCNT micro-nanocomposite was tested for hydrophobicity, and the carbon paper loaded with CoFe-S@3D-S-NCNT micro-nanocomposite was directly tested, as shown in Figure 6. It can be seen that its hydrophobic angle is 151°, which proves the excellent hydrophobicity of CoFe-S@3D-S-NCNT micro-nanocomposite, and the material with better hydrophobicity dominates the discharge polarization because the discharge polarization A large amount of oxygen is required for the reaction to proceed in the forward direction.

The ORR performance test of the prepared CoFe-S@3D-S-NCNT micro-nanocomposite is carried out, as shown in Figure 7, it can be seen that it has a high half-wave potential of 0.855V, which is close to the limiting current of 6mA/ ^cm2 density, indicating that it has excellent ORR activity.

The OER performance test of the prepared CoFe-S@3D-S-NCNT micro-nanocomposite, as shown in Figure 8, it can be seen that its overpotential at 10mA/cm ² is only a small 310mV, which is enough to show the excellent OER performance.

The ORR stability test was carried out on the prepared CoFe-S@3D-S-NCNT micro-nanocomposite, as shown in Figure 9, it can be seen that after the stability test for 7200s, its current density can still be maintained at the initial current 96%, proving that it has good stability.

The solid-state battery was assembled with polished zinc sheet as anode, PaNa (sodium polyacrylate) electrolyte, and carbon paper loaded with CoFe-S@3D-S-NCNT micro-nano composite material as cathode, and assembled into a sandwich structure quasi-solid-state zinc-air battery.

As shown in FIG. 10, it is a PaNa electrolyte, and it can be seen that it has a jelly-like gel-like substance.

The discharge polarization performance of the prepared CoFe-S@3D-S-NCNT micro-nanocomposite quasi-solid zinc-air battery was tested. The results are shown in Figure 12. It can be seen that within the test time, its open circuit voltage can be Stable at 1.479V, it can be seen that it has a large open circuit voltage.

The discharge polarization performance of the prepared CoFe-S@3D-S-NCNT micro-nano composite quasi-solid zinc-air battery was tested. The results are shown in Figure 13. The discharge function is normal and the maximum power density is 460mW/cm ² , indicating that The CoFe-S@3D-S-NCNT micro-nano composite material prepared by the method of the present invention assembles a quasi-solid-state zinc-air battery with a sandwich structure, which has high energy conversion efficiency.

The cycle performance of the prepared CoFe-S@3D-S-NCNT micro-nanocomposite quasi-solid-state zinc-air battery was tested, and the cycle charge and discharge were carried out. The results are shown in Figure 13. Before 225 cycles of continuous operation, the battery performance It remains stable, indicating that the rechargeable zinc-air battery assembled by the CoFe-S@3D-S-NCNT micro-nanocomposite prepared by the method of the present invention has better battery cycle stability.

As shown in Fig. 14, it can be seen that two CoFe-S@3D quasi-solid-state zinc-air batteries composed of CoFe-S@3D-S-NCNT micro-nanocomposite as cathode material, PaNa electrolyte, and zinc flakes - Quasi-solid-state zinc-air batteries of S-NCNT micro-nanocomposites can light up LED (3V) lamps.

Example 2

(1) Preparation of CoFe-MOF

Dissolve 0.582g cobalt nitrate (Co(NO ₃ ) ₂ 6H ₂ O) and 0.06g ferrous chloride tetrahydrate (FeCl ₂ 4H ₂ O) in 40 mL of deionized water, and dissolve 1.32 g 2 -Methylimidazole (2-MIM) was mixed with 40 mL of deionized water, aged at room temperature for 4 hours, the purple solution was washed several times with deionized water and ethanol at 6500 rpm, and dried at 80°C for 12 hours.

(2) Preparation of CoFe@3D-NCNT

The prepared CoFe-MOF purple powder was placed downstream of the porcelain boat, and melamine was placed upstream, and the porcelain boat was placed in a tube furnace for calcination. The calcination atmosphere was 95% argon + 5% hydrogen, and the calcination temperature was 800 °C. The heating time was 176 minutes, and the holding time was 1 hour. After the tube furnace cooled down naturally, the CoFe@3D-NCNT nanomaterials were obtained.

(3) Preparation of CoFe-S@3D-S-NCNT

0.7 g of sodium sulfide was ultrasonically dissolved in 40 mL of deionized water, transferred to a reactor, the CoFe@3D-NCNT black powder synthesized in step (2) was immersed in the solution, hydrothermally reacted at 120 ° C for 5 hours, cooled to room temperature, Centrifugal washing with deionized water and ethanol at 6500 rpm for several times, and drying at 80 °C, the final product CoFe-S@3D-S-NCNT nanocomposite was obtained.

Example 3

(1) Preparation of CoFe-MOF

Dissolve 0.582g cobalt nitrate (Co(NO ₃ ) ₂ 6H ₂ O) and 0.06g ferrous chloride tetrahydrate (FeCl ₂ 4H ₂ O) in 40 mL of deionized water, and dissolve 1.32 g 2 -Methylimidazole (2-MIM) was mixed with 40 mL of deionized water, aged at room temperature for 4 hours, the purple solution was washed several times with deionized water and ethanol at 6500 rpm, and dried at 80°C for 12 hours.

(2) Preparation of CoFe@3D-NCNT

The prepared CoFe-MOF purple powder was placed downstream of the porcelain boat, and melamine was placed upstream, and the porcelain boat was placed in a tube furnace for calcination. The calcination atmosphere was 95% argon + 5% hydrogen, and the calcination temperature was 800 °C. The heating time was 176 minutes, and the holding time was 1 hour. After the tube furnace cooled down naturally, the CoFe@3D-NCNT micro-nano material was obtained.

(3) Preparation of CoFe-S@3D-S-NCNT

0.7 g of sodium sulfide was ultrasonically dissolved in 40 mL of deionized water, transferred to a reaction kettle, the CoFe@3D-NCNT black powder synthesized in step (2) was immersed in the solution, hydrothermally reacted at 120 ° C for 15 hours, cooled to room temperature, Centrifugal washing with deionized water and ethanol at 6500 rpm for several times, and drying at 80 °C, the final product CoFe-S@3D-S-NCNT micro-nano composite was obtained.

The performance of the nanocomposite prepared in Example 2-3 was verified. The nanocomposite prepared in Example 2 had an ORR half-wave potential of 0.84V and an OER overpotential of 350mV. The nanocomposite prepared in Example 3 had an ORR of 0.84V. The half-wave potential was 0.83 V, and the OER overpotential was 330 mV. It was found that the product prepared with a hydrothermal time of 10 hours had better bifunctional activity.

Example 4

(1) Preparation of CoFe-MOF

Dissolve 0.582g cobalt nitrate (Co(NO ₃ ) ₂ 6H ₂ O) and 0.06g ferrous chloride tetrahydrate (FeCl ₂ 4H ₂ O) in 40 mL of deionized water, and dissolve 1.32 g 2 -Methylimidazole (2-MIM) was mixed with 40 mL of deionized water, aged at room temperature for 4 hours, the purple solution was washed several times with deionized water and ethanol at 6500 rpm, and dried at 80°C for 12 hours.

(2) Preparation of CoFe@3D-NCNT

The prepared CoFe-MOF purple powder was placed downstream of the porcelain boat, melamine was placed upstream, and the porcelain boat was placed in a tube furnace for calcination. The time was 176 minutes, and the holding time was 1 hour. After the tube furnace cooled down naturally, the CoFe@3D-NCNT nanomaterials were obtained.

(3) Preparation of CoFe-S@3D-S-NCNT

0.7 g of sodium sulfide was ultrasonically dissolved in 40 mL of deionized water, transferred to a reactor, the CoFe@3D-NCNT black powder synthesized in step (2) was immersed in the solution, hydrothermally reacted at 120 ° C for 10 hours, cooled to room temperature, Centrifugal washing with deionized water and ethanol at 6500 rpm for several times, and drying at 80 °C, the final product CoFe-S@3D-S-NCNT nanocomposite was obtained.

Example 5

(1) Preparation of CoFe-MOF

Dissolve 0.582g cobalt nitrate (Co(NO ₃ ) ₂ 6H ₂ O) and 0.06g ferrous chloride tetrahydrate (FeCl ₂ 4H ₂ O) in 40 mL of deionized water, and dissolve 1.32 g 2 -Methylimidazole (2-MIM) was mixed with 40 mL of deionized water, aged at room temperature for 4 hours, the purple solution was washed several times with deionized water and ethanol at 6500 rpm, and dried at 80°C for 12 hours.

(2) Preparation of CoFe@3D-NCNT

The prepared CoFe-MOF purple powder was placed downstream of the porcelain boat, and melamine was placed upstream, and the porcelain boat was placed in a tube furnace for calcination. The time was 176 minutes, and the holding time was 1 hour. After the tube furnace cooled down naturally, the CoFe@3D-NCNT nanomaterials were obtained.

(3) Preparation of CoFe-S@3D-S-NCNT

0.7 g of sodium sulfide was ultrasonically dissolved in 40 mL of deionized water, transferred to a reactor, the CoFe@3D-NCNT black powder synthesized in step (2) was immersed in the solution, hydrothermally reacted at 120 ° C for 10 hours, cooled to room temperature, Centrifugal washing with deionized water and ethanol at 6500 rpm for several times, and drying at 80 °C, the final product CoFe-S@3D-S-NCNT nanocomposite was obtained.

Example 6

(1) Preparation of CoFe-MOF

Dissolve 0.582g cobalt nitrate (Co(NO ₃ ) ₂ 6H ₂ O) and 0.06g ferrous chloride tetrahydrate (FeCl ₂ 4H ₂ O) in 40 mL of deionized water, and dissolve 1.32 g 2 -Methylimidazole (2-MIM) was mixed with 40 mL of deionized water, aged at room temperature for 4 hours, the purple solution was washed several times with deionized water and ethanol at 6500 rpm, and dried at 80°C for 12 hours.

(2) Preparation of CoFe@3D-NCNT

The prepared CoFe-MOF purple powder was placed downstream of the porcelain boat, melamine was placed upstream, the porcelain boat was placed in a tube furnace for calcination, the calcination atmosphere was argon, the calcination temperature was 800 °C, the heating time was 176 minutes, and the The time was 1 hour, and after the tube furnace was cooled down naturally, CoFe@3D-NCNT nanomaterials were obtained.

(3) Preparation of CoFe-S@3D-S-NCNT

0.7 g of sodium sulfide was ultrasonically dissolved in 40 mL of deionized water, transferred to a reactor, the CoFe@3D-NCNT black powder synthesized in step (2) was immersed in the solution, hydrothermally reacted at 120 ° C for 10 hours, cooled to room temperature, Centrifugal washing with deionized water and ethanol at 6500 rpm for several times, and drying at 80 °C, the final product CoFe-S@3D-S-NCNT nanocomposite was obtained.

After the same experimental verification as in Example 1, the results show that when the material prepared in Example 2 is used for the preparation of electrodes for rechargeable zinc-air batteries, its peak power density is 360 mW/cm ² , and its cycle stability is 180 cycles. Above; when the material prepared in Example 3 is used for the preparation of rechargeable zinc-air battery electrodes, its peak power density is 380 mW/cm ² , and its cycle stability is over 150 cycles; the material prepared in Example 4 is used for rechargeable zinc-air battery electrodes. When the electrode of rechargeable zinc-air battery is prepared, its peak power density is 240 mW/cm ² , and its cycle stability is more than 110 cycles; when the material prepared in Example 5 is used for the preparation of electrode of rechargeable zinc-air battery, its peak value When the power density is 240 mW/cm ² , its cycle stability is over 140 cycles; when the material prepared in Example 6 is used for the preparation of electrodes for rechargeable zinc-air batteries, its peak power density is 120 mW/cm ² , and its cycle time is 120 mW/cm 2 . The stability is more than 100 cycles. When the materials prepared in Examples 2-6 are used for the preparation of electrodes for rechargeable zinc-air batteries, they all have better power density and better cycle stability.

Comparative Example 1

Same as Example 1, the difference is that no iron element is introduced in step (1), only pure Co-MOF.

The prepared materials were tested for catalytic activity and discharge polarization. The ORR half-wave potential was 0.82V, the OER overpotential was 390mV, and the peak power density was 375 mW/cm ² . The results showed that the pure Co-MOF was annealed. After vulcanization, its electrochemical performance decreased.

Comparative Example 2

With Embodiment 1, the difference is that the calcination process in the step (2) does not introduce melamine as a carbon source and directly heats up to 800°, and then the holding time is 1 hour.

The morphology, cycling stability, catalytic activity and discharge polarization test of the prepared materials showed that the ORR half-wave potential was 0.73V, the OER overpotential was 430mV, and the peak power density was 140 mW/cm ² , and the cycle was stable. The results show that: after calcination without introducing melamine as the carbon source, carbon nanotubes will not grow in situ on the CoFe-MOF nanosheets, which reduces the electrochemical performance and the assembled quasi-solid-state zinc-air battery has poor power density .

Comparative Example 3

Same as Embodiment 1, the difference is that step (3) is omitted.

The prepared materials were tested for catalytic activity, cycle stability, and discharge polarization. The ORR half-wave potential was 0.78V, the OER overpotential was 370mV, the peak power density was 340 mW/cm ² , and the cycle stability was 100 V. Weekly, the results showed that the bifunctional activity of the non-vulcanized product decreased, and the power density of the assembled rechargeable zinc-air battery was poor.

The above results show that the CoFe-S@3D-S-NCNT nanocomposite prepared by the method of the present invention has high bifunctional catalytic activity. Good cycle stability, the invention promotes the research on the air electrode of rechargeable zinc-air battery, which plays a certain role in promoting the development of high-performance quasi-solid-state zinc-air battery air electrode material.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. within.

Claims (10)

1. The preparation method of CoFe-S@3D-S-NCNT micro-nano composite material, is characterized in that, comprises the following steps: (1) Preparation of CoFe-MOF nanosheets: the mixed solution composed of cobalt salt, iron salt aqueous solution and 2-methylimidazole aqueous solution is aged, centrifugally washed and dried to obtain CoFe-MOF; (2) Preparation of CoFe@3D-NCNT: CoFe@3D-NCNT micro-nano materials were obtained by annealing CoFe-MOF micro-nano sheets in a mixed atmosphere of argon and hydrogen in the presence of melamine; (3) Preparation of CoFe-S@3D-S-NCNT: CoFe@3D-NCNT micro-nanomaterial was immersed in sodium sulfide solution for hydrothermal reaction, washed and dried to obtain CoFe-S@3D-S-NCNT. 2. the preparation method of CoFe-S@3D-S-NCNT micro-nano composite material according to claim 1, is characterized in that, in described step (1), cobalt salt comprises cobalt nitrate, cobalt chloride or acetic acid Cobalt, the concentration of its aqueous solution is 5-20g/L; the iron salt includes ferric chloride, ferric nitrate, or ferric acetate, and the concentration of its aqueous solution is 0.5-2g/L; the concentration of 2-methylimidazole aqueous solution is 20-50g /L. 3. the preparation method of CoFe-S@3D-S-NCNT micro-nano composite material according to claim 1, is characterized in that, in the mixed atmosphere of argon and hydrogen, argon is 85-95%, and hydrogen is 5 -15%. 4. the preparation method of CoFe-S@3D-S-NCNT micro-nano composite material according to claim 1, is characterized in that, in the mixed atmosphere of argon and hydrogen, argon is 95%, and hydrogen is 5%. 5. The preparation method of CoFe-S@3D-S-NCNT micro-nano composite material according to claim 1, wherein the mass ratio of melamine to cobalt salt and iron salt is 0.05-0.2:5-20:5 -20. 6. the preparation method of CoFe-S@3D-S-NCNT micro-nano composite material according to claim 1, is characterized in that, described step (2) is to place CoFe-MOF nano sheet on tubular atmosphere furnace furnace Downstream of the tube, melamine was placed upstream, placed in an atmosphere of argon and hydrogen, and the temperature was raised to 700-900 °C within 0.5-2 hours, and the temperature was maintained for 1-2 hours. After natural cooling, CoFe@3D-NCNT was obtained. 7. The preparation method of CoFe-S@3D-S-NCNT micro-nano composite material according to claim 1, is characterized in that, in described step (3): sodium sulfide solution concentration is 10-20g/L. 8. The preparation method of CoFe-S@3D-S-NCNT micro-nano composite material according to claim 1, wherein in the step (3): a hydrothermal reaction temperature of 100-140° C., a hydrothermal reaction Time 6-18h. 9. A quasi-solid rechargeable zinc-air battery air electrode comprising any one of claims 1-8 CoFe-S@3D-S-NCNT micro-nano composite material, characterized in that CoFe-S@3D-S- Add ethanol and naphthol solution to the NCNT micro-nano composite material by ultrasonic dispersion to obtain a catalyst ink, drop the catalyst ink on carbon paper or carbon cloth, and dry to obtain a quasi-solid rechargeable zinc-air battery air electrode. 10. A quasi-solid-state zinc-air battery, comprising the air electrode prepared by the CoFe-S@3D-S-NCNT micro-nano composite material of any one of claims 1-8 as a cathode electrode; zinc sheet, zinc foil, zinc ribbon , any one of the zinc electrodes deposited in situ by carbon cloth or carbon paper is used as the anode electrode; any one of the PVA electrolyte, PaNa electrolyte, biocellulose membrane electrolyte, and acrylic gel electrolyte is assembled as a gel electrolyte to obtain a quasi-solid state Zinc-air battery.

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