Preparation method of ZIF derivative Co nanoparticles and zinc-air battery

Abstract

This application is applicable to the field of battery technology. By providing a preparation method of ZIF derivative Co nanoparticles and a zinc-air battery, precursor particles are prepared by a liquid-phase method based on zinc salt and cobalt salt, polyaniline nanoparticles are synthesized by chemical oxidative polymerization, and then the polyaniline nanoparticles are dissolved to obtain a PANI solution. The precursor particles are added to the PANI solution and stirred, and after centrifugation, CoZn-ZIF-PANI powder with polyaniline nanoparticles wrapped on the surface is obtained. The CoZn-ZIF-PANI powder is placed in a tube furnace for annealing carbonization treatment to obtain ZIF derivative Co nanoparticles. The ZIF derivative Co nanoparticles have the advantages of large specific surface area, good conductivity, low cost, rich pore structure, high activity and good stability. The prepared air electrode has more efficient ORR and OER electrocatalytic performance, can reduce the reaction energy barrier of the electrode, and improve the activity and stability.

Description

Technical Field

[0001] This application belongs to the technical field of batteries, and particularly relates to a preparation method of ZIF derivative Co nanoparticles and a zinc-air battery. Background Art

[0002] Energy shortage and environmental pollution are two severe problems faced by humanity in the current process of sustainable development. In this context, we urgently hope to achieve the sustainable development of our world with cost-effective and feasible alternative energy conversion and storage devices. In recent years, zinc-air batteries have attracted extensive attention due to their high energy density, high safety, environmental friendliness, low cost, etc., and are considered one of the feasible options for powering future power grids and electric vehicles. A zinc-air battery (referred to as a zinc-air battery) is assembled from a metal zinc plate and an air cathode. The metal zinc plate and the air cathode are immersed in an alkaline electrolyte, and electrical energy is generated through the redox reaction between the metal anode and oxygen. The air electrode (air cathode, which can be a carbon cloth coated with a catalyst) is a key part of the zinc-air battery. Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) occur during the discharge and charging processes, which largely determine the performance of the battery. However, the slow kinetics of ORR / OER may lead to a relatively high overpotential. Therefore, a certain electrocatalyst is required to accelerate these two reactions. Considering factors such as cost, activity, stability, and conductivity, rationally designing an efficient bifunctional oxygen catalyst to accelerate the reaction kinetics and reduce the reaction overpotential of ORR / OER can significantly improve the performance of the battery.

[0003] Currently, noble metal materials are the most effective catalysts for ORR / OER. However, the high cost, poor bifunctional activity, and stability of noble metals have greatly restricted their development. Therefore, the development of inexpensive and stable non-noble metal catalysts has become a research hotspot. Summary of the Invention

[0004] The embodiments of this application provide a preparation method of ZIF derivative Co nanoparticles and a zinc-air battery, which improves the application and development prospects of zinc-air batteries by designing a new type of cathode electrode catalyst material.

[0005] The first aspect of the embodiments of this application provides a preparation method of ZIF derivative Co nanoparticles, and the preparation method of the ZIF derivative Co nanoparticles includes:

[0006] Preparing precursor particles by a liquid phase method based on a zinc salt and a cobalt salt;

[0007] Synthesizing polyaniline nanoparticles by chemical oxidative polymerization;

[0008] Dissolve the polyaniline nanoparticles to obtain a PANI solution, add the precursor particles to the PANI solution, stir, and obtain CoZn-ZIF-PANI powder with the polyaniline nanoparticles coated on the surface after centrifugation;

[0009] Place the CoZn-ZIF-PANI powder in a tube furnace, and perform annealing carbonization treatment by heating from 15 - 35 °C to 800 - 950 °C at a heating rate of 2 - 10 °C under a nitrogen atmosphere to obtain the ZIF derivative Co nanoparticles.

[0010] In one embodiment, preparing the precursor particles by a liquid phase method based on zinc salt and cobalt salt includes:

[0011] Dissolve the zinc salt and the cobalt salt in deionized water according to the ratio of 0.35 - 0.45 mmol of zinc salt, 0.6 - 0.9 mmol of cobalt salt, and 5 - 15 ml of deionized water, and obtain a first solution after stirring;

[0012] Dissolve 2-methylimidazole in deionized water according to the ratio of 42 - 47 mmol of 2-methylimidazole and 60 - 80 ml of deionized water, and stir to obtain a second solution;

[0013] Mix the first solution and the second solution according to the ratio of 5 - 15 ml:60 - 80 ml, stir for 10 - 20 min, then stand and incubate for 22 - 26 h to obtain a standing solution, and perform centrifugation on the standing solution with ethanol and deionized water to obtain a first precipitate;

[0014] Dry the first precipitate under vacuum at 55 - 65 °C to obtain the precursor particles.

[0015] In one embodiment, synthesizing the polyaniline nanoparticles by chemical oxidative polymerization includes:

[0016] Dissolve the aniline in hydrochloric acid aqueous solution according to the ratio of 4.5 - 5.5 g of aniline and 40 - 60 ml of hydrochloric acid aqueous solution; wherein, the concentration of the hydrochloric acid aqueous solution is 1M;

[0017] Disperse the ammonium persulfate in 25 - 30 ml of water according to the ratio of 12 - 16 g of ammonium persulfate and 25 - 30 ml of deionized water, and cool the temperature of the mixed solution to 0 - 2 °C under stirring to obtain an ammonium persulfate solution;

[0018] Mix the ammonium persulfate solution and the aniline solution, and stir under the condition of 0 - 2 °C to obtain an aniline mixed solution;

[0019] Centrifuge the aniline mixed solution with ethanol and deionized water to obtain a second precipitate, and vacuum-dry the second precipitate at 55-65 °C to obtain a green powder;

[0020] Dissolve the green powder and perform alkalization treatment to obtain an alkalized solution. Centrifuge the alkalized solution with ethanol and deionized water to obtain a third precipitate, and vacuum-dry the third precipitate at 55-65 °C to obtain the polyaniline nanoparticles.

[0021] In one embodiment, the step of dissolving the green powder and performing alkalization treatment to obtain an alkalized solution includes:

[0022] Dissolve the green powder in an ammonia water solution and stir for 20-28 h to obtain the alkalized solution; wherein, the concentration of the ammonia water solution is 30-35%.

[0023] In one embodiment, the vacuum-drying time of the third precipitate at 55-65 °C is at least 12 h.

[0024] In one embodiment, the step of dissolving the polyaniline nanoparticles to obtain a PANI solution, adding the precursor particles to the PANI solution and stirring, and then centrifuging to obtain the CoZn-ZIF-PANI powder with the polyaniline nanoparticles coated on the surface includes:

[0025] Add 20-40 mg of the polyaniline nanoparticles to 90-110 ml of deionized water and perform ultrasonic treatment to obtain a PANI solution;

[0026] Dissolve the precursor particles in the PANI solution according to the ratio of 90-110 ml of the PANI solution to 275-320 mg of the precursor particles, and continuously stir for 2-5 h;

[0027] Centrifuge and wash the stirred solution with ethanol and deionized water to obtain a fourth precipitate, and dry the fourth precipitate under vacuum at 55-65 °C,

[0028] to obtain the CoZn-ZIF-PANI powder.

[0029] In one embodiment, the time range of the ultrasonic treatment is 15-30 min; the number of times of centrifugal washing is at least 6 times.

[0030] In one embodiment, placing the CoZn-ZIF-PANI powder into a tube furnace and annealing and carbonizing it from 15 - 35°C to 800 - 950°C at a heating rate of 2 - 10°C under a nitrogen atmosphere to obtain the ZIF derivative Co nanoparticles includes:

[0031] Placing the CoZn-ZIF-PANI powder into a ceramic boat and placing the ceramic boat into the tube furnace;

[0032] Annealing and carbonizing the CoZn-ZIF-PANI powder from 15 - 25°C to 800 - 950°C at a heating rate of 2 - 10°C under a nitrogen atmosphere to obtain the ZIF derivative Co nanoparticles;

[0033] Wherein, the temperature in the tube furnace is raised from 15 - 35°C to 800 - 950°C at a heating rate of 2 - 10°C, and the holding time at a temperature of 800 - 950°C is at least 2 h, and after the holding ends, it is naturally cooled to 15 - 35°C.

[0034] In one embodiment, the quartz tube of the tube furnace is 20 cm long, 12 mm in inner diameter, and 15 mm in outer diameter.

[0035] In the second aspect of the embodiments of the present application, a zinc-air battery is provided. The zinc-air battery includes an air electrode, and the ZIF derivative Co nanoparticles prepared by the preparation method described in any one of the above embodiments are provided on the air electrode.

[0036] The beneficial effects of the embodiments of the present application are as follows: A precursor particle is prepared by a liquid phase method based on a zinc salt and a cobalt salt, a polyaniline nanoparticle is synthesized by a chemical oxidation polymerization method, then the polyaniline nanoparticle is dissolved to obtain a PANI solution, the precursor particle is added to the PANI solution and stirred, and after centrifugation, a CoZn-ZIF-PANI powder with polyaniline nanoparticles wrapped on the surface is obtained. The CoZn-ZIF-PANI powder is placed into a tube furnace for annealing and carbonization to obtain ZIF derivative Co nanoparticles. The ZIF derivative Co nanoparticles have the advantages of large specific surface area, good conductivity, low cost, rich pore structure, high activity and good stability. The prepared air electrode has more efficient ORR and OER electrocatalytic performance, can reduce the reaction energy barrier of the electrode, and improve the activity and stability. Description of the Drawings

[0037] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 It is a schematic diagram of the steps of a method for preparing ZIF derivative Co nanoparticles provided by an embodiment of the present application;

[0039] Figure 2 It is an SEM image of a zinc-air battery cathode catalyst based on ZIF derivative Co nanoparticles provided by an embodiment of the present application;

[0040] Figure 3 It is an ORR test chart of a zinc-air battery cathode catalyst based on ZIF derivative Co nanoparticles and a commercial Pt / C catalyst provided by an embodiment of the present application;

[0041] Figure 4 It is a charge-discharge cycle stability test chart of a zinc-air battery prepared with a zinc-air battery cathode catalyst based on ZIF derivative Co nanoparticles and a commercial Pt / C catalyst provided by an embodiment of the present application. Detailed implementation manners

[0042] In the following description, specific details such as specific system structures and technologies are proposed for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0043] The following will clearly describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0044] A zinc-air battery is assembled from a metallic zinc plate and an air cathode. The metallic zinc plate and the air cathode are immersed in an alkaline electrolyte, and electrical energy is generated through the redox reaction between the metal anode and oxygen. The air electrode (which can be a carbon cloth coated with a catalyst) is a key part of the zinc-air battery. Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) occur during the discharge and charging processes, which largely determine the performance of the battery. However, the slow kinetics of ORR / OER may lead to a relatively high overpotential. Therefore, certain electrocatalysts are required to accelerate these two reactions. Considering factors such as cost, activity, stability, and conductivity, rational design of highly efficient bifunctional oxygen catalysts to accelerate the reaction kinetics and reduce the discharge and charging overpotentials of the battery can significantly improve the battery performance. Currently, noble metal materials are the most effective catalysts for ORR / OER, but the high cost, poor bifunctional activity, and stability of noble metals greatly limit their development. Generally, the air electrode of a zinc-air battery has insufficient activity, and stable power output, long-term stability, as well as good kinetics of oxygen reduction (ORR) and oxygen evolution reaction (OER) have not been achieved.

[0045] To solve the above technical problems, the embodiments of the present application provide a preparation method of ZIF derivative Co nanoparticles. Refer to Figure 1 As shown, the preparation method of the ZIF derivative Co nanoparticles in this embodiment includes step S100 to step S400.

[0046] In step S100, precursor particles are prepared by a liquid-phase method based on a zinc salt and a cobalt salt.

[0047] In this embodiment, the liquid-phase method is to dissolve the zinc salt and the cobalt salt in deionized water, then mix the solution with the solution after dissolving 2-methylimidazole, and obtain the precursor particles through centrifugation.

[0048] In some embodiments, 0.35 - 0.45 mmol (millimole) of a metal salt (the metal salt can be a cobalt salt or a cobalt-zinc salt compound) can be dissolved in 5 - 15 ml (milliliters) of deionized water, and then 42 - 47 mmol (millimoles) of 2-methylimidazole is dissolved in 60 - 80 ml (milliliters) of deionized water. The two solutions are respectively stirred for 10 - 20 min (minutes), then these two solutions are quickly mixed together and stirred for 10 - 20 min (minutes), then left to stand and incubate at room temperature for 22 - 26 h (hours), then centrifuged with ethanol and deionized water, and finally dried under vacuum at 55 - 65 °C (degrees Celsius) to obtain the precursor particles.

[0049] In step S200, polyaniline nanoparticles are synthesized by chemical oxidative polymerization.

[0050] In some embodiments, 4.5 - 5.5 g of aniline can be dissolved in 40 - 60 ml of aqueous hydrochloric acid solution, 12 - 16 g of ammonium persulfate can be dispersed in 25 - 30 ml of water, the aqueous solution containing ammonium persulfate can be kept in an ice bath, and stirred continuously for 25 - 40 min until the temperature drops to about 0 °C. Then, the pre-cooled aqueous solution of ammonium persulfate can be slowly added into the aqueous solution of aniline and hydrochloric acid, and then stirred for 0.5 - 2.5 h under ice bath conditions. Centrifugal washing can be carried out with ethanol and deionized water, and drying can be carried out under vacuum conditions at 55 - 65 °C to obtain a green product. The green product can be stirred in an aqueous ammonia solution for 22 - 26 h to carry out the deprotonation process. Then, centrifugal washing can be carried out with ethanol and deionized water, and after vacuum drying at 55 - 65 °C for 10 - 15 h, dark blue polyaniline nanoparticles (PANI particles) can be obtained.

[0051] In step S300, the polyaniline nanoparticles are dissolved to obtain a PANI solution, the precursor particles are added to the PANI solution and stirred, and after centrifugation, CoZn-ZIF-PANI powder with the polyaniline nanoparticles coated on the surface is obtained.

[0052] In some embodiments, 20 - 40 mg (milligrams) of polyaniline nanoparticles (PANI particles) can be added to 90 - 110 ml of deionized water to form a PANI solution. Then, the beaker containing the PANI solution is transferred to an ultrasonic cleaner for ultrasonic treatment. After the ultrasonic treatment is completed, 275 - 320 mg of precursor particles are added to the beaker, and then continuously stirred for 2 - 5 h (hours). The stirred solution is centrifugally washed with ethanol and deionized water, and dried under vacuum conditions at 55 - 65 °C (degrees Celsius) to obtain CoZn-ZIF-PANI powder coated with PANI.

[0053] In step S400, the CoZn-ZIF-PANI powder is placed in a tubular furnace, and annealed and carbonized at a heating rate of 2 - 10 °C from 15 - 35 °C to 800 - 950 °C under a nitrogen atmosphere to obtain the ZIF derivative Co nanoparticles.

[0054] In this embodiment, precursor particles are synthesized by a liquid-phase method, and then polyaniline nanoparticles synthesized by chemical oxidative polymerization are dissolved to obtain a PANI solution, so that PANI is wrapped on the surface of the precursor particles, obtaining a smooth and large-area three-dimensional structure. Then, the prepared CoZn-ZIF-PANI powder wrapped with the polyaniline nanoparticles is calcined at a high temperature. During the calcination process, metal ions can be reduced to the metallic state, the PANI layer and the organic ligand are carbonized into a carbon support, and unnecessary metal ions escape from the sample in the form of gas due to the high temperature, and finally ZIF derivative Co nanoparticles are prepared.

[0055] In one embodiment, in step S100, the step of preparing precursor particles by a liquid-phase method based on a zinc salt and a cobalt salt includes steps S110 to S140.

[0056] In step S110, the zinc salt and the cobalt salt are dissolved in deionized water according to the ratio of 0.35 - 0.45 mmol of zinc salt, 0.6 - 0.9 mmol of cobalt salt, and 5 - 15 ml of deionized water, and after stirring treatment, a first solution is obtained.

[0057] In the embodiment, the zinc salt and the cobalt salt are dissolved in deionized water according to the ratio of 0.35 - 0.45 mmol of zinc salt, 0.6 - 0.9 mmol of cobalt salt, and 5 - 15 ml of deionized water. For example, dissolving 0.40 mmol of Zn(NO3)2·6H2O and 0.80 mmol of Co(NO3)2·6H2O in 10 mL of deionized water can obtain the first solution.

[0058] In step S120, 2-methylimidazole is dissolved in deionized water according to the ratio of 42 - 47 mmol of 2-methylimidazole and 60 - 80 ml of deionized water, and after stirring, a second solution is obtained.

[0059] In this embodiment, 42 - 47 mmol of 2-methylimidazole is dissolved in 60 - 80 ml of deionized water, and after stirring the dissolved solution, the second solution can be obtained.

[0060] In some embodiments, 44.20 mmol of 2-methylimidazole can be dissolved in 70 mL of deionized water to obtain the second solution.

[0061] In step S130, the first solution and the second solution are mixed according to the ratio of 5 - 15 ml : 60 - 80 ml, stirred for 10 - 20 min, then left standing for 22 - 26 h to obtain a standing solution, and the standing solution is centrifuged with ethanol and deionized water to obtain a first precipitate.

[0062] In this embodiment, the first solution and the second solution are mixed and allowed to stand, and the solution after standing is centrifuged to obtain a first precipitate.

[0063] In some embodiments, 0.40 mmol of Zn(NO3)2·6H2O and 0.80 mmol of Co(NO3)2·6H2O are dissolved in 10 mL of deionized water. Then, 44.20 mmol of 2-methylimidazole is dissolved in 70 mL of deionized water. The two solutions are each stirred for ten minutes. Next, the two solutions are quickly mixed together and stirred for 10 min, then allowed to stand and incubate at room temperature (15°C - 35°C) for 24 h (hours), and then centrifuged 8 times with ethanol and deionized water to obtain the first precipitate.

[0064] In step S140, the first precipitate is dried under vacuum conditions at 55 - 65 °C to obtain the precursor particles.

[0065] In some embodiments, the first precipitate can be dried under vacuum conditions at 60 °C to obtain the precursor particles (CoZn-ZIF).

[0066] In an application embodiment, 0.40 mmol of Zn(NO3)2·6H2O and 0.80 mmol of Co(NO3)2·6H2O are dissolved in 10 mL of deionized water. Then, 44.20 mmol of 2-methylimidazole is dissolved in 70 mL of deionized water. The two solutions are each stirred for ten minutes. Next, the two solutions are quickly mixed together and stirred for 10 min, then allowed to stand and incubate at room temperature for 24 h, and then centrifuged with ethanol and deionized water at least 6 times, and finally dried under vacuum conditions at 60 °C to obtain the precursor particles (CoZn-ZIF).

[0067] In one embodiment, in step S200, the steps of synthesizing polyaniline nanoparticles by chemical oxidative polymerization include steps S210 to S250.

[0068] In step S210, aniline is dissolved in an aqueous hydrochloric acid solution according to the ratio of 4.5 - 5.5 g of aniline to 40 - 60 ml of an aqueous hydrochloric acid solution to obtain an aniline solution; wherein, the concentration of the aqueous hydrochloric acid solution is 1M.

[0069] In some embodiments, an aniline solution can be obtained by dissolving 4.66 g of aniline in 50 ml of 1M aqueous hydrochloric acid solution.

[0070] In step S220, disperse the ammonium persulfate in 25 - 30 ml of water according to the ratio of 12 - 16 g of ammonium persulfate to 25 - 30 ml of deionized water, and lower the temperature of the mixed solution to 0 - 2 °C under stirring conditions to obtain an ammonium persulfate solution.

[0071] In some embodiments, 14.26 g of ammonium persulfate can be dispersed in 26 ml of water, and the aqueous solution containing ammonium persulfate is stored in an ice bath and continuously stirred until the temperature drops to about 0 °C, and the stirring time is 30 min, thereby obtaining an ammonium sulfate solution.

[0072] In step S230, mix the ammonium persulfate solution with the aniline solution, and perform a stirring treatment under the condition of 0 - 2 °C to obtain an aniline mixed solution.

[0073] In some embodiments, the ammonium persulfate solution after the above ice bath treatment can be slowly added to the aniline solution prepared in step S210, and then, after stirring for 1 h under ice bath conditions, an aniline mixed solution is obtained.

[0074] In step S240, centrifuge the aniline mixed solution with ethanol and deionized water to obtain a second precipitate, and vacuum dry the second precipitate at 55 - 65 °C to obtain a green powder.

[0075] In some embodiments, centrifuge and wash the aniline mixed solution with ethanol and deionized water, and dry it under vacuum at 60 °C to obtain a green powder.

[0076] In step S250, dissolve the green powder and perform alkalization treatment to obtain an alkalized solution. Centrifuge the alkalized solution with ethanol and deionized water to obtain a third precipitate, and vacuum dry the third precipitate at 55 - 65 °C to obtain the polyaniline nanoparticles.

[0077] In one embodiment, the step of dissolving the green powder and performing alkalization treatment to obtain an alkalized solution includes: dissolving the green powder in an ammonia water solution and stirring for 20 - 28 h to obtain the alkalized solution; wherein, the concentration of the ammonia water solution is 30 - 35%.

[0078] In some embodiments, the green powder prepared in step S240 can be added to a 33% ammonia water solution, then stirred for 24 h to perform a deprotonation process. Then, centrifuge and wash with ethanol and deionized water, and vacuum dry at 60 °C for 12 h to obtain dark blue polyaniline nanoparticles (PANI).

[0079] In some embodiments, in step S200, 4.66 g of aniline is dissolved in 50 ml of 1M hydrochloric acid aqueous solution, 14.26 g of ammonium persulfate is dispersed in 26 ml of water, the aqueous solution containing ammonium persulfate is stored in an ice bath, and continuously stirred until the temperature drops to about 0 °C, and the stirring time is 30 min. Then the pre-cooled ammonium persulfate aqueous solution is slowly added to the aqueous solution of aniline and hydrochloric acid, and then stirred for 1 h under ice bath conditions, centrifugally washed with ethanol and deionized water, and dried under vacuum at 60 °C to obtain a green product. Subsequently, the green product is stirred in 33% ammonia aqueous solution for 24 h to carry out the deprotonation process, and then, centrifugally washed with ethanol and deionized water, and vacuum dried at 60 °C for 12 h to obtain dark blue polyaniline nanoparticles (PANI powder).

[0080] In some embodiments, in step S200, 4.66 g of aniline is dissolved in 50 ml of 1M hydrochloric acid aqueous solution, 14.26 g of ammonium persulfate is dispersed in 26 ml of water, the aqueous solution containing ammonium persulfate is stored in an ice bath, and continuously stirred until the temperature drops to about 0 °C, and the stirring time is 30 min. Then the pre-cooled ammonium persulfate aqueous solution is slowly added to the aqueous solution of aniline and hydrochloric acid, and then stirred for 1 h under ice bath conditions, centrifugally washed with ethanol and deionized water, and dried under vacuum at 60 °C to obtain a green product. Subsequently, the green product is stirred in 33% ammonia aqueous solution for 24 h to carry out the deprotonation process, and then, centrifugally washed with ethanol and deionized water, and vacuum dried at 60 °C for 12 h to obtain dark blue PANI powder.

[0081] In some embodiments, in step S200, 4.66 g of aniline is dissolved in 50 ml of 1M hydrochloric acid aqueous solution, 14.26 g of ammonium persulfate is dispersed in 26 ml of water, the aqueous solution containing ammonium persulfate is stored in an ice bath, and continuously stirred until the temperature drops to about 0 °C, and the stirring time is 30 min. Then the pre-cooled ammonium persulfate aqueous solution is slowly added to the aqueous solution of aniline and hydrochloric acid, and then stirred for 1 h under ice bath conditions, centrifugally washed with ethanol and deionized water, and dried under vacuum at 60 °C to obtain a green product. Subsequently, the green product is stirred in 33% ammonia aqueous solution for 24 h to carry out the deprotonation process, and then, centrifugally washed with ethanol and deionized water, and vacuum dried at 60 °C for 12 h to obtain dark blue PANI powder.

[0082] In one embodiment, the third precipitate is vacuum dried at 55 - 65 °C for at least 12 h.

[0083] In one embodiment, in step S300, the steps of dissolving the polyaniline nanoparticles to obtain a PANI solution, adding the precursor particles to the PANI solution, stirring, and then obtaining the CoZn-ZIF-PANI powder with the polyaniline nanoparticles coated on the surface through centrifugation include steps S310 to S330.

[0084] In step S310, 20 - 40 mg of the polyaniline nanoparticles are added to 90 - 110 ml of deionized water, and ultrasonic treatment is performed to obtain a PANI solution.

[0085] In some embodiments, 25 mg of PANI is placed in 100 mL of deionized water. Then, the beaker containing this solution is transferred to an ultrasonic cleaner, and the ultrasonic time is 20 min to obtain a PANI solution.

[0086] In step S320, the precursor particles are dissolved in the PANI solution according to the ratio of 90 - 110 ml of the PANI solution to 275 - 320 mg of the precursor particles, and continuous stirring is performed for 2 - 5 h.

[0087] In some embodiments, after the ultrasonic treatment in step S310, 280 mg of the precursor particles (CoZn-ZIF powder) are added to the beaker containing the PANI solution, and then the solution in the beaker is continuously stirred for 3 h to promote the complete dissolution of the precursor particles.

[0088] In step S330, the stirred solution is centrifugally washed with ethanol and deionized water to obtain a fourth precipitate, and the fourth precipitate is dried under vacuum at 55 - 65 °C to obtain the CoZn-ZIF-PANI powder.

[0089] In some embodiments, the solution in step S320 is centrifugally washed with ethanol and deionized water and dried under vacuum at 60 °C to obtain a dark purple CoZn-ZIF-PANI powder.

[0090] In some embodiments, in step S300, 35 mg of polyaniline nanoparticles (PANI) are placed in 100 mL of deionized water. Then, the beaker containing this solution is transferred to an ultrasonic cleaner, and the ultrasonic time is 20 min. After the ultrasonic treatment, 310 mg of CoZn-ZIF powder is added to the beaker, and then continuous stirring is performed for 3 h. Centrifugal washing is performed with ethanol and deionized water, and drying is performed under vacuum at 60 °C to obtain a dark purple CoZn-ZIF-PANI powder.

[0091] In some embodiments, in step S300, 30 mg of PANI is placed into 100 mL of deionized water. Then, the beaker containing this solution is transferred to an ultrasonic cleaner, and the ultrasonic time is 20 min. After the ultrasonic treatment ends, 300 mg of CoZn-ZIF powder is added to this beaker, and then continuous stirring is carried out for 3 h. Centrifugal washing is performed with ethanol and deionized water, and drying is carried out under vacuum conditions at 60 °C to obtain deep purple CoZn-ZIF-PANI powder.

[0092] In some embodiments, in step S300, 25 mg of PANI is placed into 100 mL of deionized water. Then, the beaker containing this solution is transferred to an ultrasonic cleaner, and the ultrasonic time is 20 min. After the ultrasonic treatment ends, 280 mg of CoZn-ZIF powder is added to this beaker, and then continuous stirring is carried out for 3 h. Centrifugal washing is performed with ethanol and deionized water, and drying is carried out under vacuum conditions at 60 °C to obtain deep purple CoZn-ZIF-PANI powder.

[0093] In one embodiment, the time range of the ultrasonic treatment is 15 - 30 min; the number of times of centrifugal washing is at least 6 times.

[0094] In one embodiment, in step S400, the step of placing the CoZn-ZIF-PANI powder into a tube furnace and performing annealing carbonization treatment at a heating rate of 2 - 10 °C from 15 - 35 °C to 800 - 950 °C under a nitrogen atmosphere to obtain the ZIF derivative Co nanoparticles includes steps S410 to S420.

[0095] In step S410, the CoZn-ZIF-PANI powder is placed into a ceramic boat, and the ceramic boat is placed into the tube furnace.

[0096] In this embodiment, the cross-sectional area of the ceramic boat is smaller than the cross-sectional area of the tube furnace, and is at least less than half of the cross-sectional area of the tube furnace. By placing the CoZn-ZIF-PANI powder into the ceramic boat, the annealing conditions can be adjusted by adjusting the position of the ceramic boat in the tube furnace.

[0097] In step S420, under a nitrogen atmosphere, the CoZn-ZIF-PANI powder is annealed and carbonized at a heating rate of 2 - 10 °C from 15 - 25 °C to 800 - 950 °C to obtain the ZIF derivative Co nanoparticles; wherein, after the temperature in the tube furnace is increased from 15 - 35 °C to 800 - 950 °C at a heating rate of 2 - 10 °C, the holding time at a temperature of 800 - 950 °C is at least 2 h, and after the holding ends, it is naturally cooled to 15 - 35 °C.

[0098] In some embodiments, in step S400, 150 mg of CoZn-ZIF-PANI is placed in a ceramic boat and then transferred to a tube furnace. Under a nitrogen atmosphere, it is heated from room temperature (15 - 35 °C) to 890 °C at a heating rate of 2 °C / min, then held at 890 °C for 2 h. Finally, it is naturally cooled to room temperature in the furnace to obtain black ZIF derivative Co nanoparticles.

[0099] In some embodiments, in step S400, 150 mg of CoZn-ZIF-PANI is placed in a ceramic boat and then transferred to a tube furnace. Under a nitrogen atmosphere, it is heated from room temperature to 900 °C at a heating rate of 2 °C / min, then held at 900 °C for 2 h. Finally, it is naturally cooled to room temperature in the furnace to obtain black ZIF derivative Co nanoparticles.

[0100] In some embodiments, in step S400, 150 mg of CoZn-ZIF-PANI is placed in a ceramic boat and then transferred to a tube furnace. Under a nitrogen atmosphere, it is heated from room temperature to 920 °C at a heating rate of 2 °C / min, then held at 920 °C for 2 h. Finally, it is naturally cooled to room temperature in the furnace to obtain black CoZn-PANI-NC powder.

[0101] In some embodiments, the parameters during the calcination process in step S400 are: heating from room temperature to 880 - 950 °C at a heating rate of 2 °C / min - 10 °C / min, holding for 2 - 3 h, and finally, naturally cooling to room temperature in the furnace to obtain ZIF derivative Co nanoparticles.

[0102] Figure 2 SEM image of a ZIF derivative Co nanoparticle provided by an embodiment of the present application, Figure 3 ORR test curve of a zinc-air battery cathode catalyst prepared from a ZIF derivative Co nanoparticle provided by an embodiment of the present application (see the curve Co(Zn)-PNC in Figure 3 ), and the ORR test curve of a commercial Pt / C catalyst (see the curve Pt / C in Figure 3 ), Figure 4 Charge-discharge cycle stability test chart of a zinc-air battery prepared from a ZIF derivative Co nanoparticle provided by an embodiment of the present application (see Co(Zn)-PNC in Figure 4 ), and a zinc-air battery with a commercial Pt / C catalyst (see Pt / C in Figure 4 ).

[0103] Combined with Figure 2 、 Figure 3 、Figure 4 As shown, the raw materials used to prepare the ZIF derivative Co nanoparticles in the embodiments of the present application are cheaper than precious metal raw materials such as the Pt / C catalyst with the best electrocatalytic effect in the market, which is more beneficial to promoting the development of the market. On the other hand, the ZIF derivative Co nanoparticles prepared in the embodiments of the present application combine the prepared PANI with the ZIF organic framework. Due to the presence of PANI, the ZIF organic framework is protected and no obvious structural collapse occurs. Moreover, the flaky structure after the high-temperature pyrolysis of PANI remains on the surface of the ZIF organic framework. Also, due to the addition of Zn, the Co nanoparticles can be better dispersed, making the Co nanoparticles embedded on its surface evenly distributed, greatly reducing the phenomenon of metal particle agglomeration. And due to the evaporation of Zn, a lot of carbon nanotubes are generated, and these carbon nanotubes can better improve the electrical conductivity of the catalyst.

[0104] In one embodiment, the quartz tube of the tube furnace has a length of 20 cm, an inner diameter of 12 mm, and an outer diameter of 15 mm.

[0105] The embodiments of the present application also provide a zinc-air battery, which includes an air electrode, and the ZIF derivative Co nanoparticles prepared by the preparation method described in any one of the above embodiments are provided on the air electrode.

[0106] The beneficial effects of the embodiments of the present application are as follows: Based on zinc salts and cobalt salts, precursor particles are prepared by a liquid-phase method, polyaniline nanoparticles are synthesized by a chemical oxidation polymerization method, and then the polyaniline nanoparticles are dissolved to obtain a PANI solution. The precursor particles are added to the PANI solution and stirred, and after centrifugation, CoZn-ZIF-PANI powder with polyaniline nanoparticles wrapped on the surface is obtained. The CoZn-ZIF-PANI powder is placed in a tube furnace for annealing and carbonization treatment to obtain ZIF derivative Co nanoparticles. The ZIF derivative Co nanoparticles have the advantages of large specific surface area, good electrical conductivity, low cost, rich pore structure, high activity and good stability. The prepared air electrode has more efficient ORR and OER electrocatalytic performance, can reduce the reaction energy barrier of the electrode, and improve the activity and stability.

[0107] In the above embodiments, the descriptions of each embodiment have their own emphases. For parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0108] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A preparation method of ZIF derivative Co nanoparticles, characterized in that, The preparation method of the ZIF derivative Co nanoparticles includes: Preparing precursor particles by a liquid-phase method based on a zinc salt and a cobalt salt; Synthesizing polyaniline nanoparticles by chemical oxidative polymerization; Dissolving the polyaniline nanoparticles to obtain a PANI solution, adding the precursor particles to the PANI solution, stirring, and performing centrifugation to obtain CoZn-ZIF-PANI powder with the polyaniline nanoparticles wrapped on the surface; Placing the CoZn-ZIF-PANI powder in a tube furnace, and performing annealing carbonization treatment by heating from 15 - 35 °C to 800 - 950 °C at a heating rate of 2 - 10 °C under a nitrogen atmosphere to obtain the ZIF derivative Co nanoparticles; The preparation of the precursor particles by a liquid-phase method based on a zinc salt and a cobalt salt includes: Dissolving the zinc salt and the cobalt salt in deionized water according to the ratio of 0.35 - 0.45 mmol of zinc salt, 0.6 - 0.9 mmol of cobalt salt, and 5 - 15 ml of deionized water, and stirring to obtain a first solution; Dissolving 2-methylimidazole in deionized water according to the ratio of 42 - 47 mmol of 2-methylimidazole and 60 - 80 ml of deionized water, and stirring to obtain a second solution; Mixing the first solution and the second solution according to the ratio of 5 - 15 ml : 60 - 80 ml, stirring for 10 - 20 min, then standing and incubating for 22 - 26 h to obtain a standing solution, and centrifuging the standing solution with ethanol and deionized water to obtain a first precipitate; Drying the first precipitate under vacuum at 55 - 65 °C to obtain the precursor particles; The synthesis of polyaniline nanoparticles by chemical oxidative polymerization includes: Dissolving the aniline in an aqueous hydrochloric acid solution according to the ratio of 4.5 - 5.5 g of aniline and 40 - 60 ml of aqueous hydrochloric acid solution; wherein, the concentration of the aqueous hydrochloric acid solution is 1 M to obtain an aniline solution; Dispersing the ammonium persulfate in 25 - 30 ml of water according to the ratio of 12 - 16 g of ammonium persulfate and 25 - 30 ml of deionized water, and cooling the temperature of the mixed solution to 0 - 2 °C under stirring to obtain an ammonium persulfate solution; Mixing the ammonium persulfate solution and the aniline solution, and stirring at 0 - 2 °C to obtain an aniline mixed solution; Centrifuging the aniline mixed solution with ethanol and deionized water to obtain a second precipitate, and vacuum drying the second precipitate at 55 - 65 °C to obtain a green powder; Dissolving the green powder and performing alkalization treatment to obtain an alkalized solution, centrifuging the alkalized solution with ethanol and deionized water to obtain a third precipitate, and vacuum drying the third precipitate at 55 - 65 °C to obtain the polyaniline nanoparticles.

2. The preparation method according to claim 1, wherein The dissolving the green powder and performing alkalization treatment to obtain an alkalized solution includes: Dissolving the green powder in an ammonia water solution, and stirring for 20 - 28 h to obtain the alkalized solution; wherein, the concentration of the ammonia water solution is 30 - 35%.

3. The preparation method according to claim 2, characterized in that, The third precipitate is vacuum-dried at 55-65 °C for at least 12 h.

4. The preparation method according to claim 1, characterized in that, Dissolving the polyaniline nanoparticles to obtain a PANI solution, adding the precursor particles to the PANI solution, stirring, and obtaining CoZn-ZIF-PANI powder with the polyaniline nanoparticles coated on the surface through centrifugation, including: Adding 20-40 mg of the polyaniline nanoparticles to 90-110 ml of deionized water, and performing ultrasonic treatment to obtain a PANI solution; Dissolving the precursor particles in the PANI solution according to the ratio of 90-110 ml of the PANI solution to 275-320 mg of the precursor particles, and continuously stirring for 2-5 h; Centrifugally washing the stirred solution with ethanol and deionized water to obtain a fourth precipitate, and drying the fourth precipitate under vacuum at 55-65 °C to obtain the CoZn-ZIF-PANI powder.

5. The preparation method according to claim 4, characterized in that, The time range of the ultrasonic treatment is 15-30 min; the number of centrifugal washing times is at least 6 times.

6. The preparation method according to claim 1, characterized in that, Placing the CoZn-ZIF-PANI powder into a tube furnace, and performing annealing carbonization treatment at a heating rate of 2-10 °C from 15-35 °C to 800-950 °C under a nitrogen atmosphere to obtain the ZIF derivative Co nanoparticles, including: Placing the CoZn-ZIF-PANI powder into a ceramic boat, and placing the ceramic boat into the tube furnace; Performing annealing carbonization treatment on the CoZn-ZIF-PANI powder at a heating rate of 2-10 °C from 15-25 °C to 800-950 °C under a nitrogen atmosphere to obtain the ZIF derivative Co nanoparticles; Wherein, the temperature in the tube furnace is increased from 15-35 °C to 800-950 °C at a heating rate of 2-10 °C, the holding time at 800-950 °C is at least 2 h, and after the holding ends, it is naturally cooled to 15-35 °C.

7. The preparation method according to claim 6, characterized in that The quartz tube of the tube furnace is 20 cm long, with an inner diameter of 12 mm and an outer diameter of 15 mm.

8. A zinc-air battery, characterized in that, The zinc-air battery includes an air electrode, and the ZIF derivative Co nanoparticles prepared by the preparation method according to any one of claims 1 to 7 are provided on the air electrode.

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