Lithium oxygen battery positive electrode catalyst and preparation method thereof

Abstract

The invention discloses a lithium oxygen battery positive electrode catalyst and a preparation method thereof, and belongs to the technical field of lithium oxygen batteries. According to the method, a transition metal element iron is adopted as a doping element of a nickel-based phosphide material, the electronic structure and surface active sites of the nickel-iron phosphide are regulated and controlled through doping, and the volume change of the material is relieved in combination with carbon coating, so that the catalytic performance and the structural stability of the catalyst are improved. The raw materials adopted by the invention are rich in reserves and low in cost, the preparation method is simple to operate, the process conditions are easy to control, and the obtained positive electrode catalyst has larger specific surface area and excellent catalytic performance. The lithium-oxygen battery prepared by adopting the lithium-oxygen battery positive electrode catalyst disclosed by the invention shows good charge-discharge specific capacity and excellent cycle stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium-oxygen battery positive electrode catalyst materials, and particularly relates to a lithium-oxygen battery positive electrode catalyst and a preparation method thereof. BACKGROUND

[0002] Lithium-oxygen batteries have high theoretical energy density (~3500 Wh kg -1 ), low cost, environmental friendliness and other characteristics, and are expected to achieve super-long distance endurance mileage, and are considered as one of the future energy storage technologies with the most development prospects. Unlike traditional lithium-ion batteries, a lithium-oxygen battery is a semi-open system, and its positive electrode material is directly obtained from the ambient air without being stored in the battery, which greatly reduces the battery mass and improves the energy efficiency. However, the practical application of the lithium-oxygen battery still faces severe challenges. The poor positive electrode side redox kinetics, the incomplete decomposition of the discharge product Li2O2 to block the oxygen transmission channels, and the generation of lithium carbonate, lithium hydroxide and other by-products result in low actual energy density, short cycle life, high overpotential and other problems of the battery. Therefore, the development of a bifunctional positive electrode catalyst with high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic performance is crucial for the performance improvement of the lithium-oxygen battery.

[0003] Studies have shown that nickel phosphide has high electrical conductivity and excellent electron transport efficiency, and the surface has abundant active sites that can effectively reduce the ORR and OER energy barriers, promote the formation and decomposition of lithium peroxide, and thus improve the charge and discharge performance and cycle performance of the lithium-oxygen battery. However, the existing nickel phosphide catalysts still have significant deficiencies: on the one hand, phosphides are prone to volume expansion and surface oxidation during the cycle process, resulting in the failure of active sites; on the other hand, the electronic structure of single metal phosphides is single, which is difficult to meet the kinetic requirements of multi-step oxygen electrochemical reactions.

[0004] In the past, there have been studies on the combination of transition metal phosphides and carbon-based materials as lithium-oxygen battery positive electrode materials. For example, Chinese Invention Patent CN111725527A prepared a nitrogen and phosphorus loaded carbon nanosheet lithium-oxygen battery positive electrode material modified by cobalt phosphide particles by combining cobalt phosphide particles with a sheet-like carbon matrix material. The first charge / discharge specific capacity can reach 15055 / 18225 mAh g -1 at a current density of 100 mAg -1 , the capacity retention rate is 87.5% after 1000 cycles at a current density of 100 mAg -1 , and the limited capacity is 600 mAh g -1Under the conditions of , it can cycle 160 times. For example, Xu Haoran of Shandong University (Xu Haoran. Synthesis of transition metal phosphides and research on the performance of lithium oxygen batteries [D]. Shandong University, 2021 (12).) composited Ni2P with nitrogen and phosphorus co-doped carbon as the positive electrode material of lithium oxygen batteries, and produced Li2P with more defects and poor crystallinity during discharge. 2-x O2, so that the battery at a current density of 100mAg -1 , limited capacity is 600mAh g -1 Under the test conditions, it can stably cycle for more than 360 cycles. Although the above work demonstrates that phosphide / carbon composites have certain improvements, their cycling performance still fails to meet the requirements of practical application. More importantly, existing strategies mainly focus on carbon support modification and the application of single transition metal phosphides. To address the inherent activity and stability deficiencies of nickel phosphide, innovative component design and structural regulation strategies are particularly needed.

[0005] By introducing iron into nickel phosphide and combining it with carbon materials, it is hoped that the electronic structure of the phosphide can be fundamentally manipulated, the properties of the active sites can be optimized, and both the bifunctional catalytic activity and structural stability can be enhanced. However, in the existing technology, research on the application of nickel-iron phosphide / carbon composite materials in lithium-oxygen battery cathodes is still blank. Summary of the Invention

[0006] To address the shortcomings of the existing technology, the present invention provides a lithium-oxygen battery cathode catalyst and its preparation method. The core of the invention lies in constructing a nickel-iron bimetallic phosphide, leveraging the synergistic effect between the two transition metal elements, nickel and iron, to optimize the material's intrinsic electronic structure and catalytically active sites. Furthermore, the introduction of a carbon matrix not only improves electrical conductivity but also effectively mitigates volume changes during cycling through its mechanical stability and structural adaptability, thereby synergistically enhancing the catalyst's catalytic activity and structural stability.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions.

[0008] A method for preparing a lithium-oxygen battery cathode catalyst comprises the following steps:

[0009] (1) Iron salt, nickel salt, urea and ammonium fluoride are mixed and dissolved in deionized water in a certain molar ratio, the concentration of transition metal ions is controlled, and a hydrothermal reaction is carried out at a certain temperature for a period of time to prepare nickel iron hydroxide precursor Ni 1-x Fe x (OH) 2～3 ;

[0010] (2) the nickel iron hydroxide precursor Ni obtained in step (1) 1-x Fe x (OH) 2～3dissolved in a mixed solution of deionized water and ethanol according to a certain mass ratio, followed by centrifugation, drying, and calcination in an inert atmosphere to obtain Ni 1-x Fe x O 1～1.5 @C.

[0011] (3) mixing Ni 1-x Fe x O 1～1.5 @C obtained in step (2) with sodium hypophosphite according to a certain mass ratio, and performing phosphating reaction under an inert atmosphere to obtain a lithium-oxygen battery positive electrode catalyst (Ni 1-x Fe x )2P@C.

[0012] Further, the iron salt in step (1) is selected from any one of ferric nitrate or ferric chloride; and the nickel salt is selected from one or more of nickel nitrate, nickel chloride or nickel acetate.

[0013] Further, the molar ratio of the iron salt, the nickel salt, urea and ammonium fluoride in step (1) is (0.2-1.0):(1.0-2.7):(8.0-12.0):(3.0-6.0); and the transition metal ion concentration is controlled to be 0.01-2 mol L -1 .

[0014] Further, the molar ratio of the iron salt, the nickel salt, urea and ammonium fluoride is (0.4-0.8):(1.2-2.4):(10.0-11.0):(5.0-6.0), and the transition metal ion concentration is controlled to be 0.02-1 mol L -1 .

[0015] Further, the hydrothermal reaction temperature in step (1) is 150-200°C, preferably 160-180°C.

[0016] Further, the hydrothermal reaction time in step (1) is 6-16h, preferably 10-12h.

[0017] Further, 0.1≤x≤0.5 in step (1).

[0018] Further, the mass ratio of the nickel-iron hydroxide precursor Ni 1-x Fe x (OH) 2～3 and glucose in step (2) is 1:(0.8-1.5), preferably 1:1.

[0019] Further, the volume ratio of deionized water and ethanol in step (2) is 1:(1-1.5), preferably 1:1.

[0020] Further, the calcination temperature in step (2) is 400-800 DEG C, preferably 500-700 DEG C.

[0021] Further, the calcination time in step (2) is 1-4 h, preferably 2-3 h.

[0022] Further, the inert atmosphere in step (2) is argon, nitrogen or a mixture thereof, preferably argon.

[0023] Further, the Ni 1-x Fe x (OH) 2～3 The mass ratio of C to sodium hypophosphite is 1:(4-10), preferably 1:(5-8).

[0024] Further, the phosphorization temperature in step (3) is 300-400 DEG C, preferably 320-350 DEG C.

[0025] Further, the phosphorization time in step (3) is 1-4 h, preferably 2.5-3.5 h.

[0026] Further, the inert atmosphere in step (3) is argon, nitrogen or a mixture thereof, preferably argon.

[0027] The application further discloses a lithium-oxygen battery cathode catalyst prepared by any of the above preparation methods.

[0028] The application further discloses application of the above lithium-oxygen battery cathode catalyst in preparation of a lithium-oxygen battery.

[0029] Further, the lithium-oxygen battery comprises a cathode, an anode, a separator and an electrolyte, wherein the cathode is the lithium-oxygen battery cathode catalyst prepared by the application.

[0030] The mechanism of the application is as follows:

[0031] The invention mechanism of the nickel-iron phosphide / carbon composite lithium-oxygen battery positive electrode catalytic material mainly lies in that: the nickel-iron bimetallic phosphide has a better intrinsic electronic structure and abundant catalytic sites than single nickel / iron phosphide, and the advantages synergize with the conductive network and structural stability provided by the carbon matrix, thereby improving the catalytic performance. Specifically, the nickel-iron phosphide lattice is rich in defects such as vacancies, which optimizes the kinetic efficiency of oxygen reduction (ORR) and oxygen evolution (OER) reactions, and reduces the overpotential of Li2O2 generation / decomposition; at the same time, the Fe atoms form strong interactions with the adjacent Ni and P atoms, enhancing the electron transfer capacity of the active sites and promoting the uniform nucleation and reversible decomposition of porous Li2O2. The carbon matrix not only provides a three-dimensional conductive framework to alleviate volume expansion, but also enhances oxygen diffusion and electrolyte permeation through the mesoporous structure, and the functional groups on the carbon surface help to adsorb Li+ and stabilize the intermediate product LiO2, thereby inhibiting side reactions and improving the positive electrode specific capacity (>19000 mAh g -1 ) and cycle stability.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] (1) The preparation method of the lithium-oxygen battery positive electrode catalyst provided by the present application uses raw materials with abundant reserves and low cost, which is suitable for large-scale production.

[0034] (2) The lithium-oxygen battery positive electrode catalyst prepared by the present application has a unique morphology, which is a three-dimensional layered structure composed of nanosheets. This special structure has a large specific surface area, which is beneficial to the mass transfer process and improves the catalytic activity of the material.

[0035] (3) The lithium-oxygen battery positive electrode catalyst prepared by the present application exhibits good charge and discharge specific capacity and cycle performance. Under a current density of 200 mAg -1 , it has a charge and discharge specific capacity of 24800 mAh g -1 / 19905 mAh g -1 ; under the test conditions of a current density of 500 mAg -1 and a cut-off capacity of 500 mAh g -1 , it can be stably cycled for 400 cycles. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 Figure 3 is an XRD test graph of the lithium-oxygen battery positive electrode catalyst prepared in Example 1 and the nickel phosphide / carbon composite material catalyst prepared in Comparative Example 1.

[0037] Figure 2 Figure 4 is an SEM graph of the lithium-oxygen battery positive electrode catalyst prepared in Example 1.

[0038] Figure 3SEM image of the nickel phosphide / carbon composite catalyst prepared in Comparative Example 1;

[0039] Figure 4 The lithium-oxygen battery prepared using the catalyst provided in Example 1, Example 2, Example 3, and Comparative Example 1 was fully charged and discharged at 200 mA g -1 Comparison graph of full charge and discharge performance at a current density of 200 mA g

[0040] Figure 5 The lithium-oxygen battery prepared using the catalyst provided in Example 1, Example 2, Example 3, and Comparative Example 1 was fully charged and discharged at 100, 200, 400, 600, 800, 1000, 100 mA g -1 Comparison graph of rate performance at a current density of 200 mA g

[0041] Figure 6 The lithium-oxygen battery prepared using the nickel phosphide / carbon composite catalyst (Ni2P@C) provided in Comparative Example 1 was fully charged and discharged at 500 mA g -1 current density, 500 mA g -1 Cycle performance graph at a limited capacity;

[0042] Figure 7 The lithium-oxygen battery prepared using the lithium-oxygen battery cathode catalyst ((Ni 0.7 Fe 0.3 )2P@C) provided in Example 1 was fully charged and discharged at 500 mA g -1 current density, 500 mA g -1 Cycle performance graph at a limited capacity;

[0043] Figure 8 The lithium-oxygen battery prepared using the lithium-oxygen battery cathode catalyst ((Ni 0.9 Fe 0.1 )2P@C) provided in Example 2 was fully charged and discharged at 500 mA g -1 current density, 500 mA g -1 Cycle performance graph at a limited capacity;

[0044] Figure 9 The lithium-oxygen battery prepared using the lithium-oxygen battery cathode catalyst ((Ni 0.5 Fe 0.5 )2P@C) provided in Example 3 was fully charged and discharged at 500 mA g -1 current density, 500 mA g -1 Cycle performance graph at a limited capacity. DETAILED DESCRIPTION

[0045] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings and embodiments. The embodiments described do not limit the present invention. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the scope of protection of the present invention.

[0046] Unless otherwise specified, the experimental instruments and drugs described below can be obtained from commercial channels.

[0047] Example 1

[0048] A method for preparing a lithium-oxygen battery cathode catalyst comprises the following steps:

[0049] (1) Preparation of reaction solution

[0050] Dissolve 0.6 mmol of ferric nitrate nonahydrate, 1.4 mmol of nickel nitrate hexahydrate, 11 mmol of urea, and 5 mmol of ammonium fluoride in 80 mL of deionized water and stir for 30 min to form a homogeneous transparent solution;

[0051] (2) Preparation of nickel iron hydroxide precursor

[0052] The mixed solution prepared in step (1) was transferred to a polytetrafluoroethylene liner for hydrothermal reaction. The reaction temperature was controlled at 160° C. and the reaction time was controlled at 12 h. After sufficient reaction, the mixture was cooled to room temperature. The reaction product was centrifuged and washed three to five times with ethanol. The nickel iron hydroxide precursor Ni was obtained after vacuum drying at 60° C. for 12 h. 0.7 Fe 0.3 (OH) 2～3 ;

[0053] (3) Preparation of Ni 0.7 Fe 0.3 O 1～1.5 @C Material

[0054] The precursor collected in step (2) was mixed with glucose in a mass ratio of 1:1 and fully dissolved in a mixed solution of 20 mL of ethanol and deionized water (V 乙醇 :V 水 =1:1), ultrasonic for 30 min, then at 6000 r min -1 After filtration, the product was vacuum dried at 60 ° C for 12 h, and the product was collected and placed in an inert atmosphere at 5 ° C min -1 The temperature was raised to 600℃ at a heating rate of 100℃ and kept at this temperature for 2h. After the tube furnace cooled to room temperature, a black sample was obtained, which was Ni 0.7 Fe 0.3 O 1～1.5 @C material.

[0055] (4) Preparation of positive electrode catalyst for lithium-oxygen batteries

[0056] The Ni collected in step (3) 0.7 Fe 0.3 O 1～1.5 @C material and sodium hypophosphite are placed in a tube furnace, and the amount of sodium hypophosphite added is Ni 0.7 Fe 0.3 O 1～1.5 @C 5 times the mass of the material, in an inert atmosphere, at 2℃min -1 The temperature was raised to 320℃ at a heating rate of 100℃ and kept at this temperature for 3h. After the tube furnace was cooled to room temperature, the obtained sample was the positive electrode catalyst (Ni 0.7 Fe 0.3 )2P@C.

[0057] Example 2

[0058] The difference between Example 2 and Example 1 is that in step (1), the amount of ferric nitrate nine hydrate used is 0.2 mmol, and the amount of nickel nitrate hexahydrate used is 1.8 mmol; in step (2), Ni 0.9 Fe 0.1 (OH) 2～3 ; In step (3), Ni 0.9 Fe 0.1 O 1～1.5 @C; In step (4), the lithium oxygen battery cathode catalyst obtained is (Ni 0.9 Fe 0.1 )2P@C.

[0059] Example 3

[0060] The difference between Example 3 and Example 1 is that in step (1), the amount of ferric nitrate nine hydrate and nickel nitrate hexahydrate used is 1 mmol; in step (2), Ni 0.5 Fe 0.5 (OH) 2～3 ; In step (3), Ni 0.5 Fe 0.5 O 1～1.5 @C; In step (4), the lithium oxygen battery cathode catalyst obtained is (Ni 0.5 Fe 0.5 )2P@C.

[0061] Comparative Example 1

[0062] The nickel phosphide / carbon composite catalyst is prepared by the following steps:

[0063] (1) Preparation of reaction solution

[0064] Dissolve 2 mmol of nickel nitrate hexahydrate, 11 mmol of urea, and 5 mmol of ammonium fluoride in 80 mL of deionized water and stir for 30 min to form a homogeneous transparent solution;

[0065] (2) Preparation of nickel hydroxide precursor

[0066] The mixed solution prepared in step (1) was transferred to a polytetrafluoroethylene liner for hydrothermal reaction, the reaction temperature was controlled at 160° C., the reaction time was controlled at 12 h, and after sufficient reaction, it was cooled to room temperature, the reaction product was fully centrifuged and washed with ethanol, filtered, and vacuum dried at 60° C. for 12 h to obtain a nickel hydroxide precursor;

[0067] (3) Preparation of Ni(OH)2@C material

[0068] The precursor collected in step (2) was mixed with glucose in a mass ratio of 1:1 and fully dissolved in a mixed solution of 20 mL of ethanol and deionized water (V 乙醇 :V 水 =1:1), ultrasonic for 30 min, then at 6000 r min -1 The product was collected and placed in an inert atmosphere at 5°C min-10 and then dried under vacuum at 60°C for 12 hours. -1 The temperature was raised to 600°C at a heating rate of 1000 ℃ and kept warm for 2 hours. After the tube furnace was cooled to room temperature, a black sample was obtained, which was the Ni(OH)2@C material.

[0069] (4) Preparation of nickel phosphide / carbon composite catalyst

[0070] The Ni(OH)2@C material collected in step (3) and sodium hypophosphite were placed in a tube furnace, wherein the amount of sodium hypophosphite added was 5 times the mass of the obtained Ni(OH)2@C material, and heated at 2°C min-1 under an inert atmosphere. -1 The temperature was raised to 320°C at a heating rate of 1000 nm and kept at this temperature for 2 h. After the tube furnace was cooled to room temperature, the obtained sample was a nickel phosphide / carbon composite catalyst (Ni2P@C).

[0071] Test Example 1

[0072] The catalysts prepared in Example 1, Example 2, Example 3 and Comparative Example 1 (all cathode catalysts) were used to prepare electrodes and their lithium-oxygen battery performance was tested by the following method: the catalyst, carbon nanotubes, and polyvinyl pyrrolidone were weighed in a mass ratio of 4:4:2, mixed with a certain volume of ethanol, and ultrasonicated for 30 minutes to obtain a slurry, which was evenly sprayed on a carbon cloth to prepare an electrode, and vacuum-dried at 65°C for 12 hours. A metal lithium sheet was used as the negative electrode, and the electrolyte was 1 mol L -1LiTFSI / TEGDME, and the separator was a glass fiber separator. All the batteries were assembled in an argon-filled glove box, and then were placed in a glass jar filled with high-purity oxygen for 8 h. The galvanostatic charge-discharge tests of the lithium-oxygen batteries were carried out on a NEWARE multichannel battery tester at room temperature.

[0073] Figure 1 The XRD test pattern of the catalyst prepared in Example 1, Example 2, Example 3 and Comparative Example 1, the diffraction peaks of which mainly correspond to Ni2P (PDF #74-1385), indicates that the lithium-oxygen battery cathode catalyst is mainly composed of Ni2P as the main phase.

[0074] Figure 2 The SEM pattern of the lithium-oxygen battery cathode catalyst prepared in Example 1 is shown in Figure 1, which shows that the material is a three-dimensional layered structure composed of multiple nanosheets.

[0075] Figure 3 The SEM pattern of the nickel phosphide / carbon composite catalyst prepared in Comparative Example 1 is shown in Figure 2, which shows that the whole presents a regular quasi-spherical shape with blurred edges.

[0076] Figure 4 The complete charge-discharge performance pattern of the lithium-oxygen battery prepared by the catalyst provided in Example 1, Example 2, Example 3 and Comparative Example 1 at a current density of 200 mAg -1 . The electrode material of the present application was tested for charge-discharge at a current density of 200 mAg -1 , and the specific capacity of the first cycle charge / discharge of Example 1 was 24800 mAh g -1 / 19905 mAh g -1 , which was much higher than the first charge-discharge capacity of the lithium-oxygen battery prepared in Comparative Example 1.

[0077] Figure 5 The rate performance comparison pattern of the lithium-oxygen battery prepared by the catalyst provided in Example 1, Example 2, Example 3 and Comparative Example 1 under different current densities; the present application was tested for charge-discharge at a current density of 100, 200, 400, 600, 800, 1000 and 100 mAg -1 , and the limiting capacity was 1000 mAg -1 . With the increase of the current density, the rate performance of the examples was obviously better than that of the comparative examples, which proved that the present application had a significant advantage in the lithium-oxygen battery at high current density.

[0078] Figure 6 、 Figure 7 and Figure 8The lithium-oxygen batteries prepared by the lithium-oxygen battery positive electrode catalysts provided by Example 1, Example 2 and Example 3 respectively have cycle performance at a current density of 500 mAg -1 , and can be stably cycled for 400 cycles, 360 cycles and 380 cycles respectively when the cut-off capacity is 500 mAh g -1 , and exhibit excellent cycle stability.

[0079] In comparison, Figure 9 The cycle performance of the lithium-oxygen battery assembled by using the nickel phosphide / carbon composite catalyst provided by Comparative Example 1 as the positive electrode material can only be stably cycled for 200 cycles under the same test conditions, which is far less than the cycle performance of the lithium-oxygen batteries prepared by the lithium-oxygen battery positive electrode catalysts (Example 1-3) of the present application.

[0080] The above only describes the preferred examples of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a lithium-oxygen battery cathode catalyst, characterized in that: The following steps are involved: (1) Iron salt, nickel salt, urea and ammonium fluoride are mixed and dissolved in deionized water in a certain molar ratio, and the concentration of transition metal ions is controlled to obtain nickel iron hydroxide precursor Ni by hydrothermal reaction. 1-x Fe x (OH) 2～3 ; (2) Ni-Fe hydroxide precursor Ni 1-x Fe x (OH) 2～3 It is mixed with glucose in a certain mass ratio and dissolved in a mixed solution of deionized water and ethanol, then centrifuged, dried, and calcined in an inert atmosphere to obtain Ni 1- x Fe x O 1～1.5 @C; (3) Ni 1-x Fe x O 1～1.5 @C and sodium hypophosphite are mixed in a certain mass and subjected to phosphating reaction under an inert atmosphere to obtain a positive electrode catalyst for lithium-oxygen batteries, which is (Ni 1-x Fe x )2P@C.

2. The preparation method according to claim 1, wherein: The iron salt in step (1) is selected from any one of ferric nitrate and ferric chloride; the nickel salt is selected from one or more of nickel nitrate, nickel chloride and nickel acetate; The molar ratio of the iron salt, nickel salt, urea and ammonium fluoride is (0.2-1.0):(1.0-2.7):(8.0-12.0):(3.0-6.0).

3. The preparation method according to claim 1, wherein: Step (1) controls the transition metal ion concentration to be 0.01 to 2 mol L -1 ; The reaction temperature of the hydrothermal reaction is 150-200° C., and the reaction time is 6-16 hours.

4. The preparation method according to claim 1, wherein: In step (1), 0.1≤x≤0.

5.

5. The preparation method according to claim 1, wherein: Step (2) Ni 1-x Fe x( OH) 2～3 The mass ratio of the precursor to glucose is 1:(0.8-1.5).

6. The preparation method according to claim 1, wherein: The centrifugal speed in step (2) is 5000-6000 r / min -1 , time is 5 to 10 minutes; The inert atmosphere is argon, nitrogen or a mixed atmosphere thereof; The heating rate of the heating calcination is 1-5° / min; the temperature is raised to 400-800°C and the temperature is kept and calcined for 1-4 hours.

7. The preparation method according to claim 1, wherein: Step (3) Ni 1-x Fe x O 1～1.5 The mass ratio of @C and sodium hypophosphite is 1:(4-10); The heating rate of the phosphating reaction process is 1-5°C min -1 , heat to 300-400℃ and react for 1-4h; The inert atmosphere is argon, nitrogen or a mixed atmosphere thereof.

8. A lithium-oxygen battery cathode catalyst prepared according to the preparation method according to any one of claims 1 to 7.

9. Use of the lithium-oxygen battery cathode catalyst according to claim 8 in the preparation of a lithium-oxygen battery.

10. The use according to claim 9, wherein the lithium-oxygen battery comprises a positive electrode, a negative electrode, a separator and an electrolyte, and is characterized in that: The positive electrode is the lithium-oxygen battery positive electrode catalyst according to claim 8.

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