Preparation method of air cathode of nickel iron oxide-nitrogen doped carbon material zinc-air battery

Abstract

The invention discloses a preparation method of an air cathode of a nickel iron oxide-nitrogen doped carbon material zinc-air battery. The preparation method comprises the following steps: preparing a water-phase ZIF-8 precursor by taking ultrapure water as a solvent and zinc nitrate hexahydrate, hexadecyl trimethyl ammonium bromide and dimethylimidazole as raw materials; the preparation method comprises the following steps: by taking nickel acetate tetrahydrate, dimethylimidazole and potassium ferricyanide as raw materials, coating Fe / Ni-PBA on the surface of a ZIF-8 precursor to obtain ZIF-8 coated Fe / Ni-PBA; and carrying out high-temperature pyrolysis on the ZIF-8 at Fe / Ni-PBA in a tubular furnace, so as to obtain the NiFe2O4 / NC electrocatalyst. The catalyst has excellent ORR / OER bifunctional activity, and as an air cathode of a zinc-air battery, high power density and excellent charge-discharge cycle stability are realized.

Description

Technical Field

[0001] The present invention relates to a class of high-efficiency and low-cost air cathode electrocatalysts for zinc-air batteries, and in particular to a preparation method of a bifunctional NiFe2O4 / NC electrocatalyst and its application in zinc-air batteries. Background Art

[0002] With the continuous development of new energy technologies, zinc-air batteries (Zn-Air Batteries) are an ideal energy conversion and storage device with growing application prospects. Future efforts require continued investment in technological research and development and industrialization to improve energy conversion efficiency, reduce costs, enhance stability, and expand application areas to achieve large-scale Zn-Air Batteries. The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key processes for energy conversion and storage in Zn-Air Batteries. However, their slow kinetics and high thermodynamic barriers severely limit their overall conversion efficiency. Although traditional precious metal catalysts (such as platinum, ruthenium, and iridium) have demonstrated outstanding performance in enhancing oxygen electrocatalytic activity, their scarcity, high cost, poor stability, and lack of bifunctionality limit their feasibility for large-scale applications. Consequently, research has shifted towards the development of resource-abundant, low-cost, non-precious metal catalysts with excellent bifunctional activity and stability.

[0003] In recent years, transition metal-nitrogen co-doped carbon-based catalysts (M-NC, M=Fe, Co, Ni, Mn…) have emerged as a promising candidate for non-precious metal-based catalysts due to their exceptional activity and stability. By manipulating the local microenvironment of surface and interface active sites, including the type of metal center, coordinating atom type, coordination number, heteroatom doping, and defects, a series of highly efficient M-NC catalysts has emerged. Iron-based catalysts, due to their optimal d-band center position, exhibit moderate adsorption strength and excellent ORR activity in volcano-shaped plots, but their OER catalytic performance is relatively poor. Ni-based catalysts, on the other hand, exhibit high catalytic activity in the OER. Therefore, the combination of iron and nickel is undoubtedly an effective strategy for developing highly efficient bifunctional catalysts. Against this backdrop, this patent reports the preparation of a NiFe2O4 / NC electrocatalyst using cubic ZIF-8 as a precursor framework by coating the ZIF-8 surface with a Prussian blue analog containing Fe and Ni (Fe / Ni-PBA) and then pyrolyzing it at high temperature. Unlike prior art methods that use bimetallic ZIF-8 as a precursor, this patent uses pure ZIF-8 as a precursor and achieves bimetallic loading by surface coating with Fe / Ni-PBA, thus avoiding the complexity and uncontrollability of the bimetallic ZIF-8 synthesis process. The NiFe2O4 / NC electrocatalyst prepared in this patent has excellent ORR / OER bifunctional catalytic activity. As the air cathode of zinc-air batteries, it achieves high power density and excellent charge-discharge cycle stability, and has potential application prospects in the field of zinc-air batteries. Although prior art studies have used Prussian blue analogs to synthesize bimetallic-based composites, these studies have not yet addressed applications in ORR / OER bifunctional catalysis and zinc-air batteries. Summary of the Invention

[0004] The present invention aims to provide a zinc-air battery air cathode electrocatalyst NiFe2O4 / NC with excellent dual functionality. The specific steps of its preparation are: Step 1: Prepare an aqueous ZIF-8 precursor using ultrapure water as solvent, zinc nitrate hexahydrate, hexadecyltrimethylammonium bromide, and dimethylimidazole as raw materials; Step 2: Using nickel acetate tetrahydrate, dimethylimidazole and potassium ferrocyanide as raw materials, Fe / Ni-PBA was coated on the surface of ZIF-8 precursor to obtain ZIF-8@Fe / Ni-PBA; Step 3: ZIF-8@PBA was pyrolyzed at high temperature in a tube furnace to obtain NiFe2O4 / NC electrocatalyst.

[0005] The ZIF-8 precursor in the present invention is obtained by uniformly mixing a dimethylimidazole solution and a zinc nitrate solution in a surfactant, hexadecyltrimethylammonium bromide.

[0006] The mass ratio of zinc nitrate hexahydrate, hexadecyltrimethylammonium bromide and dimethylimidazole is 1:2-5:12-20.

[0007] In step 2, the mass ratio of nickel acetate tetrahydrate, dimethylimidazole, and ZIF-8 is 1:2-5:45-60.

[0008] The molar ratio of nickel acetate tetrahydrate to potassium ferrocyanide is 0.5-2:1.

[0009] In the technical solution of the present invention, the ZIF-8 precursor is not pyrolyzed, but is directly coated with Fe / Ni-PBA on the surface, thereby introducing Fe species with oxygen reduction activity and Ni species with oxygen evolution reaction activity.

[0010] In the technical solution of the present invention, dimethylimidazole is used as a coordination agent to 2+ Form a stable complex and control Ni 2+ The release rate of Fe / Ni-PBA was reduced to prevent it from reacting too quickly with potassium ferrocyanide, thereby forming a uniform Fe / Ni-PBA coating layer on the surface of ZIF-8.

[0011] In step 3, high temperature pyrolysis is carried out at 800-900°C in an inert atmosphere.

[0012] The catalyst was evenly drop-coated on hydrophobic HCP120 carbon paper as the air cathode, a polished zinc plate as the anode, and a PANa hydrogel film as the electrolyte to assemble a quasi-solid-state zinc-air battery. The catalyst was evenly drop-coated on hydrophobic HCP120 carbon paper as the air cathode, a polished zinc plate as the anode, and a KOH solution containing 0.2M Zn(OAc)2·2H2O as the electrolyte to assemble a liquid zinc-air battery.

[0013] The present invention also provides a quasi-solid-state or liquid zinc-air battery, comprising the NiFe2O4 / NC electrocatalyst.

[0014] The NiFe2O4 / NC electrocatalyst and preparation method of the present invention have the following significant features: (1) Excellent ORR / OER bifunctional activity, with an oxygen reduction half-wave potential of 0.88-0.91 V vs. RHE and an oxygen evolution overpotential (10 mA cm -2 ) is 280-300 mV.

[0015] (2) As the air cathode of zinc-air batteries, it achieves high power density (the power density of quasi-solid-state batteries can reach 306 mWcm -2 The power density of liquid batteries can reach 170 mW cm -2 Above), excellent charge and discharge cycle stability (quasi-solid-state battery at 2mA cm -2The liquid battery can stably cycle charge and discharge for more than 40 times at a constant current density, and the liquid battery can cycle charge and discharge for more than 40 times at a constant current density. -2 It can be stably cycled for more than 850 h at a constant current density). BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 XRD patterns of the samples prepared in Examples 1, 2, 3 and 4.

[0017] Figure 2 SEM image of the sample prepared in Example 1.

[0018] Figure 3 LSV curves of oxygen reduction reaction and oxygen evolution reaction of samples prepared from Examples 1, 2, 3, 4, 5, 6, Pt / C and RuO2.

[0019] Figure 4 Chronoamperometric curve of the oxygen reduction reaction of the sample prepared in Example 1 with Pt / C.

[0020] Figure 5 Discharge curves and power density curves of quasi-solid-state batteries and liquid batteries assembled with the sample prepared in Example 1 and Pt / C+RuO2.

[0021] Figure 6 The sample prepared in Example 1 was used as the air cathode of the quasi-solid-state battery at a current density of 2 mA cm -2 Constant current cycle charge and discharge curve.

[0022] Figure 7 The sample prepared in Example 1 was used as the air cathode of the liquid battery with Pt / C+RuO2 at a current density of 10 mAcm -2 Constant current cycle charge and discharge curve. DETAILED DESCRIPTION

[0023] Example 1 Step 1: In beaker A, add 120 ml of ultrapure water, add 3.2 g of zinc nitrate hexahydrate, and stir until dissolved. In beaker B, add 40 ml of ultrapure water, add 10 mg of hexadecyltrimethylammonium bromide, and stir until dissolved. In beaker C, add 680 ml of ultrapure water, add 50.4 g of dimethylimidazole, and stir until dissolved. Pour the solution in beaker B into beaker A, stir until uniform at room temperature, then pour into beaker C and stir for 2 hours. Then, let it stand for 2 hours, centrifuge, wash with methanol, and dry to obtain the ZIF-8 precursor.

[0024] Step 2: Take 100 ml of ultrapure water, add 0.015 g of nickel acetate tetrahydrate and 0.06174 g of dimethylimidazole in sequence, stir to dissolve, then add 800 mg of ZIF-8 and stir until evenly dispersed. Take another 40 ml of ultrapure water, add 0.0132 g of potassium ferrocyanide and dissolve it. The above dispersion and solution are mixed while stirring, stirred at room temperature for 2 h, and the precipitate is centrifuged and dried to obtain ZIF-8@Fe / Ni-PBA white powder.

[0025] Step 3: Place the ZIF-8@Fe / Ni-PBA powder in the center of a tube furnace, heat it to 900°C at 5°C / min in a high-purity Ar atmosphere, and pyrolyze it at high temperature for 2 h to obtain a NiFe2O4 / NC electrocatalyst, which is marked as the sample in Example 1.

[0026] Figure 1 Example 1 is the XRD spectrum of the catalyst prepared in this example, which shows the presence of (002) and (101) diffraction peaks of graphitized carbon, which are beneficial to improving conductivity and loading active sites. o The sharp diffraction peak at corresponds to NiFe2O4 (PDF#10-0325), indicating that the sample of Example 1 is a NiFe2O4-supported NC electrocatalyst. The obtained sample was tested by scanning electron microscopy (e.g. Figure 2 As shown in the figure, the majority of the sample consists of well-dispersed, uniformly sized rhombic dodecahedrons approximately 150 nm in size. A slurry of this sample was prepared and dripped onto a rotating disk electrode. Its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve of case 1 in a is shown. As can be seen from the figure, at 1600 rpm, its half-wave potential is 0.89 V vs. RHE and the limiting current density is 5.93 mA cm -2 , showing excellent ORR performance. Its OER performance was tested in 1 M KOH solution. Figure 3 Example 1 in b is its OER LSV curve. It can be seen from the figure that at 10 mA cm -2 Its potential is 1.51 V vs. RHE at a current density of 280 mV, which is close to that of RuO2 (at 10 mA cm -2 The potential is 1.51 V at a current density of 1.51 V and the overpotential is 280 mV, showing excellent OER performance. Figure 4 The chronoamperometric curves of the oxygen reduction reaction of the sample from Example 1 and Pt / C were tested at a constant voltage of 0.45 V. After 2 hours, the current retention rate of Example 1 was 91%, while that of Pt / C was 83%, indicating better stability than Pt / C. Figure 5The discharge curve and power density curve of the quasi-solid-state and liquid-state batteries assembled from the samples of Example 1 were measured. The power density of the quasi-solid-state battery was as high as 306 mW cm -2 , the power density of liquid batteries can reach 170 mW cm -2 In comparison, the power density of Pt / C+RuO2 quasi-solid-state battery is 192 mWcm -2 , the power density of liquid batteries is 142 mW cm -2 , indicating that the sample of Example 1 has excellent performance as the air cathode of zinc-air battery. Figure 6 The quasi-solid-state battery assembled for the sample of Example 1 is at 2 mA cm -2 The cyclic charge and discharge curve under constant current density shows that the battery can be stably charged and discharged for 42 h. The liquid battery assembled by the sample of Example 1 is -2 The liquid battery assembled by Pt / C+RuO2 can be stably charged and discharged for 850 h at a constant current density, while the liquid battery assembled by Pt / C+RuO2 can only be charged and discharged for 250 h ( Figure 7 ), from which it can be concluded that the electrocatalyst of Example 1 has good cycle stability as the cathode of zinc-air battery.

[0027] The assembly process of the assembled quasi-solid-state battery is as follows: the catalyst is evenly drop-coated on hydrophobic HCP120 carbon paper as the air cathode, the polished zinc plate is used as the anode, and the PANa hydrogel film is used as the electrolyte to assemble the quasi-solid-state zinc-air battery.

[0028] Example 2 Step 1: The preparation process of ZIF-8 precursor is the same as that in Example 1.

[0029] Step 2: Take 100 ml of ultrapure water, add 0.015 g of nickel acetate tetrahydrate and 0.0375 g of dimethylimidazole in sequence, stir to dissolve, then add 800 mg of ZIF-8 and stir until evenly dispersed. Take another 40 ml of ultrapure water, add 0.0132 g of potassium ferrocyanide and dissolve it. The above dispersion and solution are mixed while stirring, stirred at room temperature for 3 hours, and the precipitate is centrifuged and dried to obtain ZIF-8@Fe / Ni-PBA white powder.

[0030] Step 3: Place the ZIF-8@Fe / Ni-PBA powder in the center of a tube furnace, heat it to 900 °C at 5 °C / min in a high-purity Ar atmosphere, and pyrolyze it at high temperature for 2 h to obtain the NiFe2O4 / NC electrocatalyst, which is marked as Example 2 sample.

[0031] Figure 1Example 2 shows the XRD pattern of the catalyst prepared in this example. Similar to Example 1, the sample is a NiFe2O4-supported NC electrocatalyst. A slurry of this example sample was prepared and dripped onto a rotating disk electrode. Its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve of Example 2 in a is shown. As can be seen from the figure, at 1600 rpm, its half-wave potential is 0.88 V vs. RHE and the limiting current density is 5.54 mA cm -2 , showing excellent ORR performance. Its OER performance was tested in 1 M KOH solution. Figure 3 Example 2 in b is its OER LSV curve. It can be seen from the figure that at 10 mA cm -2 Its potential at the current density is 1.52 V vs. RHE, and its overpotential is 290 mV, which is not much different from that in Example 1, showing good OER performance.

[0032] Example 3 Step 1: The preparation process of ZIF-8 precursor is the same as that in Example 1.

[0033] Step 2: Take 100 ml of ultrapure water, add 0.015 g of nickel acetate tetrahydrate and 0.075 g of dimethylimidazole in sequence and stir to dissolve, then add 800 mg of ZIF-8 and stir until evenly dispersed. Take another 40 ml of ultrapure water and add 0.0132 g of potassium ferrocyanide to dissolve. The above dispersion and solution are mixed while stirring, stirred at room temperature for 2 hours, and the precipitate is centrifuged and dried to obtain ZIF-8@Fe / Ni-PBA white powder.

[0034] Step 3: Place the ZIF-8@Fe / Ni-PBA powder in the center of a tube furnace, heat it to 900°C at 5°C / min in a high-purity Ar atmosphere, and pyrolyze it at high temperature for 2 h to obtain the NiFe2O4 / NC electrocatalyst, which is marked as the sample in Example 3.

[0035] Figure 1 Example 3 shows the XRD pattern of the catalyst prepared in this example. Similar to Examples 1-2, the sample is a NiFe2O4-supported NC electrocatalyst. A slurry of this example sample was prepared and dripped onto a rotating disk electrode. Its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve of Example 3 in a is shown. As can be seen from the figure, at 1600 rpm, its half-wave potential is 0.88 V vs. RHE and the limiting current density is 5.94 mA cm -2 , showing excellent ORR performance. Its OER performance was tested in 1 M KOH solution. Figure 3Example 3 in b is its OER LSV curve. It can be seen from the figure that at 10 mA cm -2 Its potential at the current density is 1.52 V vs. RHE, and its overpotential is 290 mV, which is not much different from that of Examples 1 and 2, showing relatively excellent OER performance.

[0036] Example 4 Step 1: The preparation process of ZIF-8 precursor is the same as that in Example 1.

[0037] Step 2: Take 100 ml of ultrapure water, add 0.01 g of nickel acetate tetrahydrate and 0.06174 g of dimethylimidazole in sequence and stir to dissolve, then add 800 mg of ZIF-8 and stir until evenly dispersed. Take another 40 ml of ultrapure water and add 0.0198 g of potassium ferrocyanide to dissolve. The above dispersion and solution are mixed while stirring, stirred at room temperature for 2 hours, and the precipitate is centrifuged and dried to obtain ZIF-8@Fe / Ni-PBA white powder.

[0038] Step 3: Place the ZIF-8@Fe / Ni-PBA powder in the center of a tube furnace, heat it to 900°C at 5°C / min in a high-purity Ar atmosphere, and pyrolyze it at high temperature for 2 h to obtain a NiFe2O4 / NC electrocatalyst, which is labeled as the sample of Example 4.

[0039] Figure 1 Example 4 shows the XRD pattern of the catalyst prepared in this example. Similar to Examples 1-3, the sample is a NiFe2O4-supported NC electrocatalyst. A slurry of this example sample was prepared and dripped onto a rotating disk electrode. Its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve of Example 4 in a is shown. As can be seen from the figure, at 1600 rpm, its half-wave potential is 0.91 V vs. RHE and the limiting current density is 6.1 mA cm -2 , showing better ORR performance. Its OER performance was tested in 1 M KOH solution. Figure 3 Example 4 in b is its OER LSV curve. It can be seen from the figure that at 10 mA cm -2 Its potential is 1.51 V vs. RHE at a current density of 280 mV, showing excellent OER performance.

[0040] Example 5 Step 1: The preparation process of ZIF-8 precursor is the same as that in Example 1.

[0041] Step 2: Take 100 ml of ultrapure water, add 0.015 g of nickel acetate tetrahydrate and 0.06174 g of dimethylimidazole in sequence and stir to dissolve, then add 800 mg of ZIF-8 and stir until evenly dispersed. Take another 40 ml of ultrapure water and add 0.0198 g of potassium ferrocyanide to dissolve. The above dispersion and solution are mixed while stirring, stirred at room temperature for 2 hours, and the precipitate is centrifuged and dried to obtain ZIF-8@Fe / Ni-PBA white powder.

[0042] Step 3: Place the ZIF-8@Fe / Ni-PBA powder in the center of a tube furnace, heat it to 900°C at 5°C / min in a high-purity Ar atmosphere, and pyrolyze it at high temperature for 2 h to obtain a NiFe2O4 / NC electrocatalyst, which is labeled as Example 5 sample.

[0043] The sample of this example was prepared into a slurry and dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve of Example 5 in a is shown. As can be seen from the figure, at 1600 rpm, its half-wave potential is 0.9 V vs. RHE and the limiting current density is 6 mA cm -2 , showing excellent ORR performance. Its OER performance was tested in 1 M KOH solution. Figure 3 Example 5 in b is its OER LSV curve. It can be seen from the figure that at 10 mA cm -2 Its potential is 1.54 V vs. RHE at a current density of 310 mV, showing excellent OER performance.

[0044] Example 6 Step 1: In beaker A, add 120 ml of ultrapure water, add 3.2 g of zinc nitrate hexahydrate, and stir until dissolved. In beaker B, add 40 ml of ultrapure water, add 8 mg of hexadecyltrimethylammonium bromide, and stir until dissolved. In beaker C, add 680 ml of ultrapure water, add 50.4 g of dimethylimidazole, and stir until dissolved. Pour the solution in beaker B into beaker A, stir until uniform at room temperature, then pour into beaker C and stir for 2 hours. Then, let it stand for 2 hours, centrifuge, wash with methanol, and dry to obtain the ZIF-8 precursor.

[0045] Step 2: Take 100 ml of ultrapure water, add 0.015 g of nickel acetate tetrahydrate and 0.06174 g of dimethylimidazole in sequence, stir to dissolve, then add 800 mg of ZIF-8 and stir until evenly dispersed. Take another 40 ml of ultrapure water, add 0.0132 g of potassium ferrocyanide and dissolve it. The above dispersion and solution are mixed while stirring, stirred at room temperature for 2 h, and the precipitate is centrifuged and dried to obtain ZIF-8@Fe / Ni-PBA white powder.

[0046] Step 3: Place the ZIF-8@Fe / Ni-PBA powder in the center of a tube furnace, heat it to 900°C at 5°C / min in a high-purity Ar atmosphere, and pyrolyze it at high temperature for 2 h to obtain a NiFe2O4 / NC electrocatalyst, which is labeled as Example 6 sample.

[0047] The ORR LSV curve of the sample in this example is as follows Figure 3 As shown in Example 6, it can be seen from the figure that at 1600 rpm, its half-wave potential is 0.9 V vs. RHE and the limiting current density is 6.04 mA cm -2 , ORR performance is excellent. Figure 3 Example 6 in b is its OER LSV curve at 10 mA cm -2 The potential is 1.57 V vs. RHE at the current density, and the overpotential is 340 mV ( Figure 3 b), showing even better OER performance.

[0048] Compared with Example 1, the experimental steps and experimental chemicals remain unchanged, and only dimethylimidazole is not added in the second step. The resulting catalyst has an ORR half-wave potential lower than 0.86 V vs. RHE, and an OER overpotential greater than 400 mV, reaching 460 mV.

[0049] Compared with Example 1, if the experimental steps and experimental chemicals are kept unchanged, and nickel acetate tetrahydrate is not added in the second step, the OER overpotential of the obtained catalyst is greater than 400 mV, reaching 458 MV, and the performance is significantly reduced.

[0050] Compared with Example 1, if the experimental steps and experimental chemicals remain unchanged and potassium ferrocyanide is not added in the second step, Ni-PBA cannot be coated on the surface of ZIF-8.

Claims

1. A method for preparing an air cathode of a nickel iron oxide-nitrogen doped carbon material zinc-air battery, characterized in that: The steps include: Step 1: Prepare an aqueous ZIF-8 precursor using ultrapure water as solvent, zinc nitrate hexahydrate, hexadecyltrimethylammonium bromide, and dimethylimidazole as raw materials; Step 2: Using nickel acetate tetrahydrate, dimethylimidazole and potassium ferrocyanide as raw materials, Fe / Ni-PBA was coated on the surface of ZIF-8 precursor to obtain ZIF-8@Fe / Ni-PBA; Step 3: Pyrolyze ZIF-8@Fe / Ni-PBA at high temperature in a tube furnace to obtain NiFe2O4 / NC electrocatalyst, i.e., nickel iron oxide-nitrogen doped carbon material zinc-air battery air cathode.

2. The preparation method according to claim 1, characterized in that In step 1, the mass ratio of zinc nitrate hexahydrate, hexadecyltrimethylammonium bromide, and dimethylimidazole is 1:2-5:12-20.

3. The preparation method according to claim 1, characterized in that In step 2, the mass ratio of nickel acetate tetrahydrate, dimethylimidazole, and ZIF-8 is 1:2-5:45-60.

4. The preparation method according to claim 1, characterized in that The molar ratio of nickel acetate tetrahydrate to potassium ferrocyanide is 0.5-2:

1.

5. The preparation method according to claim 1, characterized in that The reaction time for coating Fe / Ni-PBA on the surface of ZIF-8 precursor is 1-3 hours.

6. The preparation method according to claim 1, characterized in that In step 3, high temperature pyrolysis is carried out at 800-1000° C. in an inert atmosphere.

7. The NiFe2O4 / NC electrocatalyst prepared according to the method according to any one of claims 1 to 6, characterized in that: ZIF-8@Fe / Ni-PBA was used as an electrocatalyst precursor and NiFe2O4 / NC electrocatalyst was obtained by high-temperature pyrolysis.

8. The NiFe2O4 / NC electrocatalyst according to claim 7, characterized in that The catalyst has dual functions of catalyzing oxygen reduction reaction and oxygen evolution reaction.

9. The NiFe2O4 / NC electrocatalyst according to claim 7, characterized in that Its application as air cathode in quasi-solid-state or liquid zinc-air batteries.

10. Quasi-solid-state or liquid zinc-air battery, characterized in that Comprising the NiFe2O4 / NC electrocatalyst according to claim 7.

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