Noble metal-free high-entropy alloy lithium-oxygen battery positive electrode catalyst as well as preparation method and application thereof

Abstract

The invention provides a noble-metal-free high-entropy alloy lithium-oxygen battery positive electrode catalyst as well as a preparation method and application thereof. The preparation method of the lithium-oxygen battery positive electrode catalyst comprises the following steps: fully dissolving a surfactant, a copper salt, a cobalt salt, a nickel salt, a manganese salt, a molybdenum salt, a cerium salt and a reducing agent in a solvent, reacting, centrifuging, washing, and re-dispersing into a dispersing agent to obtain NHEA (at) CeOx nano-particle dispersion liquid; and fully mixing and dispersing the dispersion liquid and the conductive carbon black dispersion liquid, and then centrifuging, washing and drying to obtain the conductive carbon black. The catalyst is simple in preparation method, low in cost and suitable for large-scale production. The catalyst can be directly applied as a lithium-oxygen battery positive electrode catalyst, has extremely high catalytic activity, optimizes the morphology of a discharge product Li2O2, and greatly improves the capacity, cycle performance, application temperature range and other performances of a lithium-oxygen battery.

Description

Technical Field

[0001] The present invention belongs to the fields of material synthesis and electrochemical energy storage, and particularly relates to a noble-metal-free high-entropy alloy lithium-oxygen battery cathode catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Currently, more than 80% of the global energy demand is supplied by fossil fuels. The excessive use of fossil energy releases a large amount of CO2 gas, leading to global warming and the "greenhouse effect". Developing clean and renewable energy sources such as solar energy, wind energy, and tidal energy is the key to addressing the energy crisis and environmental pollution problems caused by the depletion of traditional fossil energy. Developing new energy storage systems is an effective means to solve the intermittent dilemma of green energy utilization and achieve efficient storage and distribution. The rapid development of new energy vehicles also urgently demands high-safety, high-performance, and low-cost power batteries. Since 1991, lithium-ion batteries have been widely used in portable electronic devices, smart grids, and electric vehicles due to their advantages such as long cycle life and no memory effect. Currently, commercial lithium-ion batteries based on graphite anodes have reached their energy density limit (350 Wh kg -1 ), but still cannot meet the urgent demand for high energy density in long-range electric vehicles. Therefore, developing new power batteries to replace lithium-ion batteries is of crucial strategic significance for changing the energy storage pattern and breaking through the development bottleneck of new energy vehicles.

[0003] Metal-oxygen batteries based on oxygen redox chemistry, including lithium-oxygen batteries (Li-O2), sodium-oxygen batteries (Na-O2), potassium-oxygen batteries (K-O2), zinc-air batteries (Zn-air), and aluminum-oxygen batteries (Al-O2), etc., have attracted high research and development interest in the scientific and industrial communities. Theoretically, compared with lithium-ion batteries using metal oxides as the cathode, metal-oxygen batteries use O2 as the active material, thus having higher theoretical energy density, lower cost, and environmental friendliness. Among them, lithium-oxygen batteries are the most concerned metal-oxygen batteries at present. A lithium-oxygen battery is a energy storage technology based on a lithium metal anode and using oxygen as the cathode active material to release electrical energy through an electrochemical reaction. Therefore, among all types of batteries, lithium-oxygen batteries can exhibit the highest energy density (3500 Wh kg -1 ), and the achievable energy density is expected to reach 600 Wh kg -1, is an important power supply system for electric vehicles capable of achieving a driving range of 500 - 800 km, making it one of the most attractive candidates for the next generation of electrochemical energy storage systems. Looking at the entire development history, from the concept proposal to the application, lithium - oxygen batteries have made great progress in technical research and industrialization. As early as 1996, Abraham first reported a non - aqueous lithium - oxygen battery composed of a lithium metal anode, an organic polymer electrolyte, and a porous carbon - oxygen cathode, and achieved reversible charge - discharge of the battery. In 2006, Bruce et al. first realized the reversible formation / decomposition reaction of Li2O2, initiating a research upsurge on lithium - oxygen battery systems among researchers. In 2008, Toyota officially established a "Battery Research Department" to accelerate the practical application of lithium - oxygen batteries. In 2009, IBM in the United States launched the "Battery 500" project, aiming to develop high - specific - energy lithium - oxygen battery technology to meet the need for a 500 - km driving range of electric vehicles, actively promoting the practical development of lithium - oxygen batteries. Subsequently, Natural Resources Canada approved a 5 - to 10 - year R & D project named "High - Energy - Density Energy Storage System for Vehicles" in 2017, proposing to develop a lithium - oxygen battery with 1000 Wh kg -1 . Nowadays, research institutions such as the Pacific Northwest National Laboratory, the United States Army Research Laboratory, and Argonne National Laboratory under the US Department of Energy are also increasing their research efforts in the direction of lithium - oxygen batteries.

[0004] Although non-aqueous lithium-oxygen batteries have advantages such as high energy density, high efficiency, cleanliness, safety, and good cycling performance, they have become strong candidates for the next-generation energy storage system. However, due to the intrinsic shortcomings of the electrochemical reactions in lithium-oxygen batteries, their electrochemical performance is difficult to meet the requirements of practical applications, specifically manifested as severe charge-discharge polarization (low energy utilization rate), low actual capacity, poor rate performance, and short cycle life. Specifically, lithium metal at the negative electrode is prone to dendrite formation and dead lithium, and reacts with oxygen diffused from the positive electrode to cause corrosion; the electrolyte is vulnerable to attack by intermediate superoxide ions and degrades, and is also prone to volatilization in an open battery system; the positive electrode lacks efficient and stable bifunctional catalysts for ORR (oxygen reduction reaction) and OER (oxygen evolution reaction), resulting in high polarization potential and limited cycle life. Currently, the main methods for protecting the negative electrode are similar to those of other lithium-metal batteries, mostly by fabricating coatings on the lithium-metal surface or forming artificial SEI films. The main solutions to the electrolyte problem lie in finding stable and non-volatile electrolyte systems and the application of solid electrolytes. Among them, the positive electrode catalyst and the mass transfer structure have the most crucial impact on the electrochemical performance of the battery. The root cause is that the redox reaction in the lithium-oxygen battery mainly occurs at the three-phase interface of the positive electrode, and the discharge product lithium peroxide formed is an insulating substance with a wide bandgap. Therefore, the positive electrode has to undertake three main functions: current collector, electrolyte channel (oxygen and lithium-ion diffusion), and lithium peroxide deposition space, making it play the most important role in the performance of lithium-oxygen batteries. Therefore, the development of low-cost and high-performance positive electrode catalysts is of great significance for the practical application of lithium-oxygen batteries.

[0005] Currently, the mainstream cathode catalytic materials include carbon materials, noble metals and their compounds, transition metals and their compounds, and other catalytic materials. Among them, although carbon materials have high electrical conductivity and excellent catalytic performance, they face the insurmountable problem of being easily decomposed to produce lithium carbonate by-products under the attack of superoxide ions, and are currently often used as auxiliary materials to increase electrical conductivity. For example, Chinese patent document CN106299552A discloses a preparation method of a graphitized carbon nanotube flexible film lithium-air battery, using a graphitized carbon nanotube flexible film as the air cathode. First, a carbon nanotube dispersion is prepared; then, an aluminum foil or a copper foil is used as the substrate to prepare a carbon nanotube film; finally, the prepared carbon nanotube film is carbonized, graphitized, and rolled to obtain a graphitized carbon nanotube flexible film. However, the preparation method of the cathode catalytic material designed in this invention requires harsh conditions such as high temperature and the catalyst is only a carbon material, resulting in limited battery performance. Noble metals and their oxides have excellent catalytic performance and quite high stability. For example, Chinese patent document CN118712401A discloses a carbon-supported PtFe sub-nanocluster for the cathode catalysis of a lithium-oxygen battery, achieving good performance. However, Pt used in the patent belongs to noble metals, which are scarce in resources and expensive in price, and are not suitable for large-scale applications. Therefore, considering comprehensively the catalytic function, stability, and cost, the non-precious metal high-entropy alloy formed by alloying transition metals has catalytic activity that can replace noble metals and more excellent stability, and is therefore regarded as a very competitive catalyst system. To sum up, how to reasonably design a non-precious metal high-entropy alloy catalyst, regulate its composition, morphology, and defects to achieve the most optimized catalytic performance, ensure the reversible formation and decomposition of lithium peroxide, inhibit the generation of by-products, and improve battery performance is the current research focus. Summary of the Invention

[0006] Aiming at the deficiencies of existing lithium-oxygen battery cathode catalysts in terms of catalytic activity, stability, and cost, the present invention provides a non-precious metal high-entropy alloy lithium-oxygen battery cathode catalyst, its preparation method, and application. The present invention synthesizes CuCoNiMnMoCe six-element non-precious metal high-entropy alloy nanoparticles by a mild oil-phase co-reduction method. The addition of rare earth element Ce induces alloy twinning to form five-fold twinned nanoparticles and at the same time forms a CeO x layer on its surface, constituting core-shell structure nanoparticles, and loading them on the surface of carbon black to obtain a catalyst. The catalyst preparation method of the present invention is simple, low in cost, and suitable for large-scale production. The catalyst of the present invention can be directly applied as a lithium-oxygen battery cathode catalyst, has extremely high catalytic activity, optimizes the morphology of the discharge product Li2O2, and greatly improves the performance of the lithium-oxygen battery such as capacity, cycle performance, and application temperature range.

[0007] The technical solution of the present invention is as follows:

[0008] A non-precious-metal high-entropy alloy lithium-oxygen battery cathode catalyst, the microscopic morphology of the catalyst is: five-fold twinned CuCoNiMnMoCe six-element non-precious-metal high-entropy alloy nanoparticles coated with an amorphous CeO x layer are loaded on the surface of conductive carbon black.

[0009] Preferably according to the present invention, the particle size of the five-fold twinned CuCoNiMnMoCe six-element non-precious-metal high-entropy alloy nanoparticles coated with an amorphous CeO x layer is 10-20 nm, and the thickness of the amorphous CeO x layer is 1.5-2.5 nm.

[0010] The preparation method of the above non-precious-metal high-entropy alloy lithium-oxygen battery cathode catalyst includes the steps:

[0011] (1) A surfactant, copper salt, cobalt salt, nickel salt, manganese salt, molybdenum salt, cerium salt and a reducing agent are fully dissolved in a solvent, reacted, and then centrifuged and washed and redispersed in a dispersant to obtain a NHEA@CeO x nanoparticle dispersion;

[0012] (2) The NHEA@CeO x nanoparticle dispersion and the conductive carbon black dispersion are fully mixed and dispersed, and then centrifuged, washed and dried to obtain a non-precious-metal high-entropy alloy lithium-oxygen battery cathode catalyst, that is, NHEA@CeO x / C powder.

[0013] Preferably according to the present invention, the surfactant in step (1) is cetyltrimethylammonium chloride.

[0014] Preferably according to the present invention, the copper salt in step (1) is copper acetylacetonate or copper acetate; the cobalt salt is cobalt acetylacetonate or cobalt acetate; the nickel salt is nickel acetylacetonate or nickel acetate; the manganese salt is manganese acetylacetonate or manganese acetate; the molybdenum salt is molybdenum hexacarbonyl; the cerium salt is cerium acetylacetonate.

[0015] Preferably according to the present invention, the reducing agent in step (1) is L-ascorbic acid, D-anhydrous glucose or borane morpholine complex. Preferably, the reducing agent is a combination of L-ascorbic acid, D-anhydrous glucose and borane morpholine complex, and the molar ratio of L-ascorbic acid, D-anhydrous glucose and borane morpholine complex is 0.2-0.4:0.2-0.4:0.6-0.8, preferably 0.3:0.33:0.705.

[0016] Preferably according to the present invention, the solvent in step (1) is oleylamine; the total molar amount of the copper salt, cobalt salt, nickel salt, manganese salt, molybdenum salt and cerium salt and the volume ratio of the solvent is 0.03-0.06 mol / L.

[0017] Preferably according to the present invention, the molar ratio of the surfactant, copper salt, cobalt salt, nickel salt, manganese salt, molybdenum salt, cerium salt, and reducing agent in step (1) is (4.5 - 9):(2 - 3):(2 - 3):(2 - 3):(2 - 3):(10 - 15):(0.5 - 1.5):(130 - 140), preferably (4.5 - 9):2.5:2.5:2.5:2.5:12.5:(0.5 - 1.5):133.5, and further preferably 9:2.5:2.5:2.5:2.5:12.5:1:133.5.

[0018] Preferably according to the present invention, the reaction temperature in step (1) is 230 - 260 °C, and the reaction time is 4 - 6 h; preferably, the reaction temperature is 245 °C and the reaction time is 5 h.

[0019] Preferably according to the present invention, the detergent used for washing in step (1) is a mixture of cyclohexane and ethanol, and the volume ratio of cyclohexane to ethanol is 1:3 - 5, preferably 1:3.

[0020] Preferably according to the present invention, the dispersant in step (1) is cyclohexane; the volume ratio of the dispersant to the solvent is 1 - 3:1.

[0021] Preferably according to the present invention, the conductive carbon black dispersion in step (2) is an ethanol dispersion of conductive carbon black; the concentration of the conductive carbon black dispersion is 2 - 3 g / L.

[0022] Preferably according to the present invention, the mass ratio of the conductive carbon black in the conductive carbon black dispersion in step (2) to the copper salt in step (1) is 2 - 5:1.

[0023] Preferably according to the present invention, the sufficient mixing and dispersion in step (2) is ultrasonic mixing for 1 - 2 h.

[0024] The application of the above - mentioned noble - metal - free high - entropy alloy lithium - oxygen battery cathode catalyst is used as a cathode active material in a lithium - oxygen battery.

[0025] Preferably according to the present invention, the application method includes the steps of: thoroughly grinding and mixing the lithium - oxygen battery cathode catalyst and the binder, adding N - methylpyrrolidone or isopropanol, and sufficiently dispersing to obtain a slurry; then uniformly coating it on carbon paper and drying to obtain the lithium - oxygen battery cathode; preferably, the mass ratio of the lithium - oxygen battery cathode catalyst to the binder is 3 - 5:1; the binder is polytetrafluoroethylene or polyvinylidene fluoride.

[0026] Preferably, in the lithium - oxygen battery cathode, the loading amount of the lithium - oxygen battery catalyst is 0.2 - 0.3 mg cm -2 。

[0027] Preferably according to the present invention, the lithium-oxygen battery includes a positive electrode, a negative lithium sheet, a separator, and an organic electrolyte; the organic electrolyte is prepared by dissolving lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in tetraethylene glycol dimethyl ether (TEGDME), and the concentration of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is 0.5 - 1 mol L -1 .

[0028] Technical features and beneficial effects of the present invention:

[0029] 1. The present invention develops a low-cost hydrogen-rich reducing agent and uses a low-temperature oil-phase co-reduction method to prepare penta-twinned CuCoNiMnMoCe six-element noble-metal-free high-entropy alloy nanoparticles coated with an amorphous CeO x layer, and then loads them on the surface of conductive carbon black to obtain a high-performance and low-cost noble-metal-free high-entropy alloy catalyst, which is used as the positive electrode material of an advanced lithium-oxygen battery after being loaded on carbon paper. The catalyst preparation method adopted by the present invention is simple, mild in conditions, expandable and low in cost, and is suitable for large-scale production; the synthesized catalyst has extremely high catalytic activity and stability, and the assembled lithium-oxygen battery has extremely high cycle stability, and its performance such as capacity and application temperature range has been greatly improved.

[0030] 2. The present invention uses copper salt, cobalt salt, nickel salt, manganese salt, molybdenum salt, cerium salt, a reducing agent and a surfactant as raw materials, and synthesizes penta-twinned CuCoNiMnMoCe six-element noble-metal-free high-entropy alloy nanoparticles coated with an amorphous CeO x layer under mild and controllable reaction conditions; then the nanoparticles are loaded on conductive carbon black to prepare an efficient catalyst. The catalyst of the present invention has a large number of efficient reaction active sites, which accelerates the reaction kinetics. The addition of Ce atoms in the present invention has multiple functions: firstly, Ce with a large atomic radius induces significant lattice stress and strain after entering the CuCoNiMnMo lattice, further leading to the transformation of the alloy nanoparticles from single crystal to penta-twinned; secondly, Ce with extremely low electronegativity is extremely easy to combine with oxygen to form an amorphous CeO x layer on the surface of the alloy nanoparticles, thus forming a unique structure of a penta-twinned noble-metal-free high-entropy alloy surface coated with an amorphous oxide layer.

[0031] 3. During the preparation of the NHEA@CeO x nanoparticles of the present invention, the selected transition metal salts are specific types of salts, and special ligands such as acetylacetonate ions or acetate ions effectively control the reduction process to ensure the formation of high-entropy alloy nanoparticles. In addition, the presence of a surfactant is also essential, which ensures that the generated NHEA@CeO x has good dispersibility and uniform size. Without the presence of a surfactant, the generated NHEA@CeO xThe nanoparticles have different sizes and shapes and poor dispersibility, which loses the advantages of nanoparticles. The specific types of raw materials and the proportions of the present invention are conducive to obtaining the NHEA@CeO x Nanoparticles.

[0032] 4. NHEA@CeO of the present invention x The choice of reducing agent is crucial during nanoparticle preparation. The present invention prefers borane morpholine, D-anhydrous glucose, and L-ascorbic acid as a mixed reducing agent, and molybdenum hexacarbonyl as the molybdenum salt. This is achieved by utilizing the heating and decomposition of borane morpholine and molybdenum hexacarbonyl to produce H2 and CO, respectively, creating a strong reducing atmosphere. This, combined with the exceptional electron-accepting abilities of D-anhydrous glucose and L-ascorbic acid, overcomes the significant miscibility barrier between non-precious metal elements.

[0033] 5. NHEA@CeO of the present invention x / C is amorphous CeO coated on conductive carbon black x The five-fold twinning of the alloy nanoparticles in the present invention results in five exposures of the active (111) crystal plane, significantly increasing the number of active sites; the surface CeO x The contact between the layer and the internal alloy forms a semiconductor-metal heterojunction. The difference in work function between the two causes electrons to spontaneously move from CeO x Transferred to the active sites Cu and Ni on the alloy surface. The increase in charge density at the active sites fills the d orbital, weakening the binding energy with oxygen species, accelerating the reaction kinetics while inhibiting the oxidation of the active sites and enhancing the cycle stability. On the other hand, the amorphous and porous CeO x The protective layer inhibits the leaching of alloy metal atoms and "stores" reactants (Li + and O2), ensuring structural stability and wide temperature range operability. x When used as the positive electrode of lithium-oxygen batteries, the C / C material exhibits good electrochemical performance, effectively inhibits side reactions, greatly reduces the generation of by-products (lithium carbonate, lithium hydroxide, etc.), optimizes the morphology of the discharge product Li2O2, and improves the battery capacity and battery cycle life: 100mA g -1 At a current density of 1.5 GHz, the first discharge capacity is as high as 17987 mAh g -1 , when the cut-off capacity is 1000mAh g -1 It can achieve an overpotential of 0.39V and can stably cycle 405 times at high current density. More importantly, it can stably cycle 245 times and 145 times at extreme temperatures of -20 and 80 degrees Celsius, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1a is the TEM image of the Pt nanoparticles prepared in step 1) of Comparative Example 1; Figure 1 b is the TEM image of the alloy nanoparticles prepared in step 1); Figure 1 c is the NHEA@CeO prepared in Example 1 x TEM image; Figure 1 d is the NHEA@CeO prepared in Example 1 x HAADF-STEM image.

[0035] Figure 2 a is the HRTEM image of the alloy nanoparticles prepared in step 1) of Comparative Example 2; Figure 2 b is the HRTEM image of the NHEA@CeO prepared in Example 1 x ; Figure 2 c, d are the HAADF-STEM images of the NHEA@CeO prepared in Example 1 x .

[0036] Figure 3 is the mapping image of the NHEA@CeO prepared in Example 1 x .

[0037] Figure 4 is the XRD pattern of the alloy nanoparticles (NHEA) prepared in Comparative Example 2 and the NHEA@CeO prepared in Example 1 x .

[0038] Figure 5 a-h are the synchrotron radiation characterization patterns of NHEA / C (abbreviation: NHEA) prepared in Comparative Example 2 and NHEA@CeO x / C (abbreviation: NHEA@CeO x ). Figure 5 i is a schematic diagram of the heterojunction formed at the interface between the alloy (NHEA) and CeO x .

[0039] Figure 6 a is the cyclic voltammogram (CV) of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Comparative Example 1 (abbreviation: Pt), Comparative Example 2 (abbreviation: NHEA), and Example 1 (NHEA@CeO x ); Figure 6 b is the charge-discharge curve of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Comparative Example 1 (abbreviation: Pt), Comparative Example 2 (abbreviation: NHEA), and Example 1 (NHEA@CeO x ) under the condition of a current density limit specific capacity of 1000 mAh g -1 at 200 mA g -1 ; Figure 6c is the first-cycle discharge curve (voltage-capacity curve without capacity limitation) of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Comparative Example 1 (abbreviated as Pt), Comparative Example 2 (abbreviated as NHEA), and Example 1 (NHEA@CeO x ) at a current density of 100 mA g -1 ; Figure 6 d is the rate performance test curve of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Comparative Example 1 (abbreviated as Pt), Comparative Example 2 (abbreviated as NHEA), and Example 1 (NHEA@CeO x ). Figure 6 e is the cycle life diagram of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Comparative Example 1 (abbreviated as Pt), Comparative Example 2 (abbreviated as NHEA), and Example 1 (NHEA@CeO x ) at 25 °C under the condition of a current density limiting specific capacity of 1000 mAh g -1 ; -1 Figure 6 f is the cycle life diagram of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (NHEA@CeO x ) at 80 °C under the condition of a current density limiting specific capacity of 600 mAh g -1 ; -1 Figure 6 g is the cycle life diagram of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (NHEA@CeO x ) at -20 °C under the condition of a current density limiting specific capacity of 600 mAh g -1 ; -1

[0040] Figure 7 a, b, and c are the SEM images of the discharge products of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Comparative Example 1 (abbreviated as Pt), Comparative Example 2 (abbreviated as NHEA), and Example 1 (NHEA@CeO x ), respectively.

[0041] Figure 8 a is the XRD pattern of the discharge products of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (NHEA@CeO x ) at different cycle numbers; Figure 8 b is the XRD pattern of the discharge products of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Comparative Example 1 (abbreviated as Pt) and Comparative Example 2 (abbreviated as NHEA); Figure 8 c is the XPS Li 1s fine spectrum of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (NHEA@CeO x ) in different states.

[0042] ​​​Figure 9 It is the HAADF-STEM image of the alloy nanoparticles prepared in Example 4.

[0043] Figure 10 It is the HAADF-STEM image of the alloy nanoparticles prepared in Example 5.

[0044] Figure 11 a is the charge-discharge curve of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (abbreviated as NHEA@CeO x ), Example 4 (abbreviated as NHEA@CeO x -1.5), and Example 5 (abbreviated as NHEA@CeO x -3.2) at a current density of 200 mA g -1 with a limited specific capacity of 1000 mAh g -1 ; Figure 11 b is the first-cycle discharge curve (voltage-specific capacity curve without capacity limitation) of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (NHEA@CeO x ), Example 4 (abbreviated as NHEA@CeO x -1.5), and Example 5 (abbreviated as NHEA@CeO x -3.2) at a current density of 100 mA g -1 .

[0045] Figure 12 It is the HAADF-STEM and EDS mapping images of the catalyst prepared in Comparative Example 3.

[0046] Figure 13 a is the charge-discharge curve of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (abbreviated as NHEA@CeO x ) and Comparative Example 3 (abbreviated as S-NHEA) at a current density of 200 mA g -1 with a limited specific capacity of 1000 mAh g -1 ; Figure 13 b is the first-cycle discharge curve (voltage-specific capacity curve without capacity limitation) of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (NHEA@CeO x ) and Comparative Example 3 (abbreviated as S-NHEA) at a current density of 100 mA g -1 . Detailed implementation manners

[0047] The present invention will be further described below through specific examples in conjunction with the accompanying drawings, but is not limited thereto.

[0048] The raw materials used in the examples are all conventional raw materials and can be obtained commercially; the methods are all prior arts without special instructions.

[0049] Example 1

[0050] A preparation method of a non-noble metal high-entropy alloy lithium-oxygen battery cathode catalyst is as follows:

[0051] 1) Preparation of NHEA@CeO x nanoparticles: Dissolve 30 mg (0.09 mmol) of cetyltrimethylammonium chloride in 5 ml of oleylamine and sonicate for 15 minutes, then add 6.5 mg (0.025 mmol) of copper acetylacetonate, 8.9 mg (0.025 mmol) of cobalt acetylacetonate, 6.4 mg (0.025 mmol) of nickel acetylacetonate, 8.8 mg (0.025 mmol) of manganese acetylacetonate, 5 mg (0.01 mmol) of cerium acetylacetonate, 33 mg (0.125 mmol) of hexacarbonylmolybdenum, 60 mg (0.30 mmol) of L-ascorbic acid, 60 mg (0.33 mmol) of D-anhydrous glucose and 70 mg (0.705 mmol) of borane morpholine complex. After sonication for 1 h to dissolve, react at 245 °C in an oil bath for 5 h, then centrifuge and wash twice with a cyclohexane / ethanol solution with a volume ratio of 1:3 (11000 rpm, 2 min), and disperse in 10 ml of cyclohexane to obtain NHEA@CeO x nanoparticle dispersion.

[0052] 2) Preparation of NHEA@CeO x / C: Add a 10 ml ethanol solution in which 25 mg of conductive carbon black (C) is dispersed to the above dispersion, sonicate for 2 h to mix, centrifuge, wash with ethanol (8000 rpm, 3 min), and dry in vacuum at 60 °C for 12 h to obtain NHEA@CeO x / C powder.

[0053] Preparation of lithium-oxygen battery cathode: Grind and mix 8 mg of NHEA@CeO x / C powder and 2 mg of polyvinylidene fluoride (PVDF), add to 1.5 ml of N-methylpyrrolidone (NMP) to obtain a slurry, stir for 12 h, then uniformly coat on carbon paper and dry to obtain the lithium-oxygen battery cathode. Calculate the loading amount of the active material (i.e., NHEA@CeO x / C) to be 0.2 - 0.3 mg cm -2 .

[0056] Example 2

[0057] A preparation method of a non-noble metal high-entropy alloy lithium-oxygen battery cathode catalyst is as described in Example 1, except that:

[0058] In step 1), 15 mg (0.045 mmol) of cetyltrimethylammonium chloride was dissolved in 5 ml of oleylamine and ultrasonicated for 15 minutes, then 5 mg (0.025 mmol) of copper acetate, 4.8 mg (0.025 mmol) of manganese acetate, 5 mg (0.01 mmol) of cerium acetylacetonate, 4.4 mg (0.025 mmol) of cobalt acetate and 4.4 mg (0.025 mmol) of nickel acetate, as well as 33 mg (0.125 mmol) of molybdenum hexacarbonyl, 60 mg (0.30 mmol) of L-ascorbic acid, 60 mg (0.33 mmol) of D-anhydrous glucose and 70 mg (0.705 mmol) of borane morpholine complex were added. After ultrasonicating for 1 h to dissolve, the reaction was carried out at 245 °C in an oil bath for 5 h, then centrifuged and washed twice with a cyclohexane / ethanol solution with a volume ratio of 1:3 (11000 rpm, 2 min) and dispersed in 10 ml of cyclohexane to obtain an NHEA@CeO x nanoparticle dispersion.

[0059] Other steps and conditions are the same as those in Example 1.

[0060] The preparation method of the positive electrode of the lithium-oxygen battery is the same as that in Example 1.

[0061] Example 3

[0062] The preparation method of a noble-metal-free high-entropy alloy lithium-oxygen battery positive electrode catalyst is the same as that in Example 1.

[0063] Preparation of the positive electrode of the lithium-oxygen battery: 8 mg of NHEA@CeO x / C powder and 2 mg of polytetrafluoroethylene (PTFE) were ground and mixed, then added to 2 ml of isopropanol to obtain a slurry, stirred for 12 h, and then evenly coated on carbon paper and dried to obtain the positive electrode of the lithium-oxygen battery. Calculate the loading of the active material (i.e., NHEA@CeO x / C) is 0.2 - 0.3 mg cm -2 .

[0064] Example 4

[0065] A preparation method of a noble-metal-free high-entropy alloy lithium-oxygen battery positive electrode catalyst is as described in Example 1, except that: in step 1), the amount of cerium acetylacetonate used is 2.5 mg (0.005 mmol); other steps and conditions are the same as those in Example 1.

[0066] The preparation method of the positive electrode of the lithium-oxygen battery is the same as that in Example 1.

[0067] Example 5

[0068] A preparation method of a non-noble-metal high-entropy alloy lithium-oxygen battery cathode catalyst, as described in Example 1, except that: in step 1), the amount of cerium acetylacetonate used is 7.5 mg (0.015 mmol); other steps and conditions are the same as those in Example 1.

[0069] The preparation method of the lithium-oxygen battery cathode is the same as that in Example 1.

[0070] Comparative Example 1

[0071] A preparation method of a Pt nanoparticle lithium-oxygen battery catalyst is as follows:

[0072] 1) Preparation of Pt nanoparticles: Dissolve 15 mg of cetyltrimethylammonium chloride in 5 ml of oleylamine and sonicate for 15 minutes, then add 9.8 mg of platinum acetylacetonate and 60 mg of D-anhydrous glucose. After sonication for 1 h to dissolve, react in an oil bath at 230 °C for 2 h, then centrifuge and wash twice with a cyclohexane / ethanol solution with a volume ratio of 1:3 (11000 rpm, 2 min), and disperse in 10 ml of cyclohexane to obtain a Pt nanoparticle dispersion.

[0073] 2) Loading of Pt nanoparticles: Add 10 ml of an ethanol solution in which 25 mg of conductive carbon black (C) is dispersed to the above dispersion, sonicate for 2 h to mix, centrifuge, wash with ethanol (8000 rpm, 3 min), and dry in vacuum at 60 °C for 12 h to obtain Pt / C powder.

[0074] Preparation of the lithium-oxygen battery cathode: Grind and mix 8 mg of Pt / C powder and 2 mg of polyvinylidene fluoride (PVDF), then add to 1.5 ml of N-methylpyrrolidone (NMP) to obtain a slurry, stir for 12 h, and then evenly coat on carbon paper. After drying, the lithium-oxygen battery cathode is obtained. Calculate the loading amount of the active substance (i.e., Pt / C) to be 0.2 - 0.3 mg cm -2 .

[0075] Comparative Example 2

[0076] A preparation method of a lithium-oxygen battery catalyst, as described in Example 1, except that: cerium acetylacetonate is not added in step 1); other steps and conditions are the same as those in Example 1. NHEA / C powder is obtained.

[0077] Preparation of the lithium-oxygen battery cathode: Grind and mix 8 mg of NHEA / C powder and 2 mg of polyvinylidene fluoride (PVDF), then add to 1.5 ml of N-methylpyrrolidone (NMP) to obtain a slurry, stir for 12 h, and then evenly coat on carbon paper. After drying, the lithium-oxygen battery cathode is obtained. Calculate the loading amount of the active substance (i.e., NHEA / C powder) to be 0.2 - 0.3 mg cm -2 .

[0078] Comparative Example 3

[0079] A preparation method of a lithium-oxygen battery catalyst, as described in Comparative Example 2, except that: in step 1), the reducing agents borane morpholine and L-ascorbic acid are not added; other steps and conditions are the same as those in Comparative Example 2. S-NHEA / C powder is obtained.

[0080] Preparation of the lithium-oxygen battery cathode: 8 mg of S-NHEA / C powder and 2 mg of polyvinylidene fluoride (PVDF) are ground and mixed, and then added to 1.5 ml of N-methylpyrrolidone (NMP) to obtain a slurry, which is stirred for 12 h and then evenly coated on carbon paper, and dried to obtain the lithium-oxygen battery cathode. Calculate the loading amount of the active material (i.e., S-NHEA / C powder) to be 0.2 - 0.3 mg cm -2 。

[0083] Test Example 1

[0084] The TEM pattern of the Pt nanoparticles prepared in step 1) of Comparative Example 1 is as Figure 1 a; the TEM pattern of the alloy nanoparticles prepared in step 1) of Comparative Example 2 is as Figure 1 b; the TEM and HAADF-STEM patterns of the NHEA@CeO x prepared in Example 1 are as Figure 1 c, d; it can be seen from the figure that the NHEA@CeO x obtained in the present invention is a five-twinned CuCoNiMnMoCe high-entropy alloy nanoparticle with a CeO x layer coated on the surface.

[0085] Test Example 2

[0086] The HRTEM patterns of the alloy nanoparticles prepared in step 1) of Comparative Example 2 and the NHEA@CeO x prepared in Example 1 are as Figure 2 a, b shown, indicating that the alloy nanoparticles prepared in step 1) of Comparative Example 2 are single crystals with good crystallinity, while the NHEA@CeO x involved in the present invention is in a five-twinned state, which is due to the severe strain generated by Ce entering the lattice interior, further inducing the evolution of the single crystal to a five-twinned state.

[0087] The HAADF-STEM pattern of the NHEA@CeO x prepared in Example 1 is as Figure 2 c, d shown, proving that the surface of the five-twinned nanoparticles is evenly coated with an amorphous CeO x layer with a thickness of about 2 nm, which is formed by the combination of ultra-low electronegativity Ce and oxygen.

[0088] The NHEA@CeO prepared in Example 1 x 's mapping spectrum is as shown in Figure 3 , which proves that Cu, Co, Ni, Mn, Mo, and Ce are evenly distributed at the internal crystallization of the nanoparticles, while the surface-dispersed Ce and O signals prove that the composition of the amorphous layer is CeO x .

[0089] The XRD spectra of the alloy nanoparticles (NHEA) prepared in Step 1) of Comparative Example 2 and the NHEA@CeO prepared in Example 1 x are as shown in Figure 4 . As can be seen from the figure, the alloy nanoparticles prepared in Comparative Example 2 have good crystallinity and a face-centered cubic structure, mainly exposing three crystal planes. The different diffraction peak positions from the five transition metals prove the formation of the alloy structure. Compared with the alloy nanoparticles prepared in Comparative Example 2, the NHEA@CeO prepared in Example 1 x shows a slight negative shift in the diffraction peak position, proving that the entry of Ce into the lattice causes an increase in the lattice spacing. The absence of the CeO x characteristic peak proves its amorphous nature.

[0090] The XAFS spectra of the NHEA / C (abbreviated as NHEA) prepared in Comparative Example 2 and the NHEA@CeO x / C (abbreviated as NHEA@CeO x ) prepared in Example 1 are as shown in Figure 5 a - h. Analysis shows that the introduction of CeO x increases the number of electrons at the Cu and Ni sites and significantly reduces the bonding number of Cu and Ni with O. This result indicates that the introduction of CeO x significantly weakens the adsorption of oxygen species by the active sites, which is beneficial to accelerating the reaction kinetics and improving the cycle stability.

[0091] Test Example 3

[0092] The positive electrodes of the lithium - oxygen batteries prepared in the examples and comparative examples were cut into the required electrode sizes for button - type CR2032 (circular discs with a diameter of 13 mm) using a punching machine. A lithium metal sheet was used as the negative electrode, glass fiber was used as the separator, and a 1 mol L -1 lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solution in tetraethylene glycol dimethyl ether (TEGDME) was used as the organic electrolyte. Button - type CR2032 lithium - oxygen batteries were assembled in a glove box with a water and oxygen content of less than 0.5 ppm and subjected to electrochemical tests in an oxygen test chamber at 1.0 - bar.

[0093] Figure 6 a is Comparative Example 1 (abbreviated as Pt), Comparative Example 2 (abbreviated as NHEA), Example 1 (abbreviated as NHEA@CeO x)The cyclic voltammetry curve (CV) of the lithium-oxygen battery assembled with the positive electrode of the prepared lithium-oxygen battery at a scanning rate of 0.1 mV s -1 As can be seen from the figure, the lithium-oxygen battery catalyst prepared in Example 1 of the present invention has a higher ORR onset potential and a lower OER onset potential, and the largest integral area indicates its better bifunctional catalytic activity.

[0094] Figure 6 b shows the charge-discharge curves of the lithium-oxygen batteries assembled with the positive electrodes of lithium-oxygen batteries prepared in Comparative Example 1 (abbreviated as Pt), Comparative Example 2 (abbreviated as NHEA), and Example 1 (abbreviated as NHEA@CeO x ) at a current density of 200 mA g -1 with a specific capacity limit of 1000 mAh g -1 under the condition. As can be seen from the figure, the lithium-oxygen battery catalyst prepared in Example 1 of the present invention has a higher discharge potential and a lower charge potential, and the charge-discharge overpotential is only 0.39 V, far lower than that of Pt (0.88 V) and Comparative Example 2 (1.07 V); at the same time Figure 6 c shows the first-cycle charge-discharge curve (voltage-specific capacity curve without capacity limitation) at a current density of 100 mA g -1 , indicating that the lithium-oxygen battery catalyst prepared in Example 1 has an ultra-high initial discharge specific capacity of 17987 mAh g -1 , far higher than that of Comparative Example 1 (13295 mAh g -1 ) and Comparative Example 2 (11939 mAh g -1 [[ID=2)2]], indicating that the lithium-oxygen battery catalyst prepared in the present invention has more excellent bifunctional catalytic activity.

[0095] Figure 6 d shows the rate performance test curves of the lithium-oxygen batteries assembled with the positive electrodes of lithium-oxygen batteries prepared in Comparative Example 1 (abbreviated as Pt), Comparative Example 2 (abbreviated as NHEA), and Example 1 (abbreviated as NHEA@CeO x ). It can be found by comparison that the lithium-oxygen battery catalyst prepared in Example 1 of the present invention has the lowest charge-discharge overpotential at each current density and has the best rate performance.

[0096] Figure 6 e shows the lithium-oxygen batteries assembled with the positive electrodes of lithium-oxygen batteries prepared in Comparative Example 1 (abbreviated as Pt), Comparative Example 2 (abbreviated as NHEA), and Example 1 (abbreviated as NHEA@CeO x ) at 25 °C at a current density of 500 mA g -1 with a specific capacity limit of 1000 mAh g -1Cycling life graph under the conditions; It can be seen from the graph that the lithium-oxygen battery catalyst prepared in Example 1 of the present invention has good catalytic activity and can inhibit the occurrence of side reactions, so it has a relatively high cycling life (405 cycles).

[0097] Figure 6 f is the cycling life graph of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (abbreviated as NHEA@CeO x ) at 80 °C under a current density limit specific capacity of 600 mAh g -1 ; -1 Cycling life graph under the conditions; Figure 6 g is the cycling life graph of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (abbreviated as NHEA@CeO x ) at -20 °C under a current density limit specific capacity of 600 mAh g -1 ; It can be seen from the graph that the lithium-oxygen battery catalyst prepared in Example 1 of the present invention can stably cycle 245 cycles and 145 cycles respectively at extreme temperatures of -20 and 80 °C, has good catalytic activity, and has operability in an ultra-wide temperature range. -1 Cycling life graph under the conditions;

[0098] Test Example 4

[0099] Figure 7-8 is the characterization of the discharge products during the charge and discharge process of the battery to illustrate the charge and discharge mechanism and the inhibition of the side reaction process. The morphological characterizations of the discharge products of the lithium-oxygen batteries assembled with the positive electrodes of the lithium-oxygen batteries prepared in Comparative Example 1 (abbreviated as Pt), Comparative Example 2 (abbreviated as NHEA), and Example 1 (abbreviated as NHEA@CeO x ) after discharging for 10 hours at a current density of 500 mA g -1 are shown in Figure 7 a, b, c; The XRD patterns of the discharge products of the lithium-oxygen batteries assembled with the positive electrodes of the lithium-oxygen batteries prepared in Example 1 (abbreviated as NHEA@CeO x ) at different cycle numbers with a cut-off capacity of 1000 mAh g -1 and a current density of 500 mA g -1 are shown in Figure 8 a; The XRD patterns of the discharge products of the lithium-oxygen batteries assembled with the positive electrodes of the lithium-oxygen batteries prepared in Comparative Example 1 (abbreviated as Pt) and Comparative Example 2 (abbreviated as NHEA) after discharging for 10 hours at a current density of 500 mA g -1 are shown in Figure 8 b; The XRD patterns of the discharge products of the lithium-oxygen batteries assembled with the positive electrodes of the lithium-oxygen batteries prepared in Example 1 (abbreviated as NHEA@CeO x ) in the initial state, after discharging for 5 hours at a current density of 500 mA g -1 , and after discharging for 5 hours at a current density of 500 mA g -1Discharge at a current density of 500 mA g⁻¹ for 10 hours -1 Charge at a current density of 500 mA g⁻¹ for 5 hours -1 The XPS Li 1s fine spectrum after charging at a current density for 10 hours is as shown Figure 8 from top to bottom in c.

[0100] Figure 7 a is the SEM image of the discharge product with the material prepared in Comparative Example 1 as the cathode. It can be seen that the discharge product of the Pt cathode is erythrocyte-shaped. Combining with Figure 8 b, its main discharge product is erythrocyte-shaped Li₂O₂. This morphology of lithium peroxide is formed by solution growth. The discharge product nucleates and grows in the solution. The large-volume erythrocyte-shaped Li₂O₂ has a limited contact area with the catalyst, which is not conducive to electron transfer and product decomposition. Figure 7 b is the SEM image of the discharge product with the material prepared in Comparative Example 2 as the cathode. It can be seen that the discharge product is film-shaped. Combining with Figure 8 b, its main discharge product is film-shaped Li₂O₂. This morphology of lithium peroxide is formed by surface growth. The discharge product nucleates and grows on the catalyst surface. The formation of film-shaped Li₂O₂ will cover the active sites, which is not conducive to suppressing side reactions. While the discharge product of the material prepared in Example 1 of the present invention as the cathode is as shown Figure 7 in c, which is nano-flower-shaped lithium peroxide composed of fine needles. This morphology of lithium peroxide is formed by the synergistic growth of surface and solution growth, does not cover the active sites, can maintain the efficient utilization of the cathode catalyst, and avoid the occurrence of side reactions. Therefore, the battery has excellent electrochemical properties such as high capacity, high rate, and long cycle life.

[0101] Test Example 5

[0102] The HAADF-STEM images of the alloy nanoparticles prepared in Step (1) of Example 4 and Example 5 are respectively as shown Figure 9 and 10 shown.

[0103] It can be seen from Figure 9 that a smaller Ce doping amount results in a thinner CeO x layer with a thickness of about 1.5 nm.

[0104] It can be seen from Figure 10 that a larger Ce doping amount results in a thicker CeO x layer with a thickness of about 3.2 nm.

[0105] Test Example 6

[0106] Example 4 (NHEA@CeO x -1.5), Example 5 (NHEA@CeO xThe positive electrode of the lithium-oxygen battery prepared in -3.2) was assembled into a button-type CR2032 lithium-oxygen battery according to the method of Test Example 3, and electrochemical tests were carried out in an oxygen test chamber at 1.0 bar.

[0107] Figure 11 a is the charge-discharge curves of the lithium-oxygen batteries assembled with the positive electrodes of Example 1 (abbreviated as NHEA@CeO x ), Example 4 (NHEA@CeO x -1.5), and Example 5 (NHEA@CeO x -3.2) at a current density limit specific capacity of 1000 mAh g -1 ; -1 condition; Figure 11 b is the first-cycle charge-discharge curve (voltage-specific capacity curve without capacity limitation) at a current density of 100 mA g -1 .

[0108] It can be seen from Figure 11 that the catalytic performances of NHEA@CeO x -1.5 and NHEA@CeO x -3.2 are both lower than that of NHEA@CeO x , including the overpotential at a current density of 200 mA g -1 and the discharge capacity at a current density of 100 mA g -1 . The specific reason is that the too thin CeO x layer cannot transfer enough electrons to the internal alloy nanoparticles to optimize the adsorption energy of the active sites for key intermediate products; the too thick CeO x layer hinders the adsorption of reactants onto the internal alloy nanoparticles for subsequent reactions. Therefore, NHEA@CeO x with a moderate CeO x thickness has the best catalytic performance.

[0109] Test Example 7

[0110] The HAADF-STEM images and mapping spectra of the alloy nanoparticles prepared in Step 1) of Comparative Example 3 are as Figure 12 shown.

[0111] It can be seen from Figure 12 that the catalyst using only D-anhydroglucose as a reducing agent shows an obvious phase separation morphology, which is caused by insufficient reducing ability.

[0112] Test Example 8

[0113] The positive electrode of the lithium-oxygen battery prepared in Comparative Example 3 (S-NHEA) was assembled into a button-type CR2032 lithium-oxygen battery according to the method of Test Example 3, and electrochemical tests were carried out in an oxygen test chamber at 1.0 bar.

[0114] Figure 13 a is the charge-discharge curve of the lithium-oxygen battery assembled with the positive electrode of the lithium-oxygen battery prepared in Example 1 (abbreviated as NHEA@CeO x ) and Comparative Example 3 (S-NHEA) at a current density-limited specific capacity of 1000 mAh g -1 ; -1 Condition; Figure 13 b is the first-cycle charge-discharge curve (voltage-specific capacity curve without capacity limitation) at a current density of 100 mA g -1 .

[0115] It can be seen from Figure 13 that due to the obvious phase separation phenomenon of the catalyst obtained in Comparative Example 3, the catalytic performance (overpotential and discharge specific capacity) is worse than that of the catalyst obtained in Example 1.

Claims

1. A non-precious metal high-entropy alloy lithium-oxygen battery cathode catalyst, characterized in that, The microscopic morphology of the catalyst is as follows: Quintuple-twinned CuCoNiMnMoCe high-entropy alloy nanoparticles coated with an amorphous CeO x layer are supported on the surface of conductive carbon black.

2. The positive electrode catalyst of the non-precious metal high-entropy alloy lithium-oxygen battery according to claim 1, characterized in that, The particle size of the quintuple twinned CuCoNiMnMoCe high-entropy alloy nanoparticles coated with amorphous CeO x layer is 10-20 nm, and the thickness of the amorphous CeO x layer is 1.5-2.5 nm.

3. The preparation method of the non-precious metal high-entropy alloy lithium-oxygen battery cathode catalyst as claimed in claim 1 or 2, comprising the steps: (1) Dissolve surfactants, copper salts, cobalt salts, nickel salts, manganese salts, molybdenum salts, cerium salts and reducing agents fully in a solvent, react, and then after centrifugation and washing, redisperse them in a dispersant to obtain a dispersion of NHEA@CeO x nanoparticle dispersion; (2) NHEA@CeO x The nanoparticle dispersion and the conductive carbon black dispersion were fully mixed and dispersed, and then centrifuged, washed, and dried to obtain a noble metal-free high entropy alloy lithium-oxygen battery cathode catalyst, namely NHEA@CeO x / C powder.

4. The preparation method of the non-noble metal high-entropy alloy lithium-oxygen battery cathode catalyst according to claim 3, characterized in that In step (1), one or more of the following conditions are included: i. The surfactant is cetyltrimethylammonium chloride; ii. The copper salt is copper acetylacetonate or copper acetate; the cobalt salt is cobalt acetylacetonate or cobalt acetate; the nickel salt is nickel acetylacetonate or nickel acetate; the manganese salt is manganese acetylacetonate or manganese acetate; the molybdenum salt is hexacarbonylmolybdenum; the cerium salt is cerium acetylacetonate; iii. The solvent is oleylamine; the total molar amount of the copper salt, cobalt salt, nickel salt, manganese salt, molybdenum salt, and cerium salt and the volume ratio of the solvent are 0.03 - 0.06 mol / L.

5. The preparation method of the non-precious metal high-entropy alloy lithium-oxygen battery cathode catalyst according to claim 3, characterized in that, The reducing agent in step (1) is L-ascorbic acid, D-anhydrous glucose, or borane morpholine complex; preferably, the reducing agent is a combination of L-ascorbic acid, D-anhydrous glucose, and borane morpholine complex, and the molar ratio of L-ascorbic acid, D-anhydrous glucose, and borane morpholine complex is 0.2 - 0.4:0.2 - 0.4:0.6 - 0.8, preferably 0.3:0.33:0.

705.

6. The preparation method of the non-precious metal high-entropy alloy lithium-oxygen battery cathode catalyst according to claim 3, characterized in that, The molar ratio of the surfactant, copper salt, cobalt salt, nickel salt, manganese salt, molybdenum salt, cerium salt, and reducing agent in step (1) is (4.5 - 9):(2 - 3):(2 - 3):(2 - 3):(2 - 3):(10 - 15):(0.5 - 1.5):(130 - 140), preferably (4.5 - 9):2.5:2.5:2.5:2.5:12.5:(0.5 - 1.5):133.5, and further preferably 9:2.5:2.5:2.5:2.5:12.5:1:133.

5.

7. The preparation method of the non-precious-metal high-entropy alloy lithium-oxygen battery cathode catalyst according to claim 3, characterized in that In step (1), one or more of the following conditions are included: i. The reaction temperature is 230 - 260 °C, and the reaction time is 4 - 6 h; preferably, the reaction temperature is 245 °C, and the reaction time is 5 h; ii. The dispersant is cyclohexane; the volume ratio of the dispersant and the solvent is 1 - 3:

1.

8. The preparation method of the non-precious-metal high-entropy alloy lithium-oxygen battery cathode catalyst according to claim 3, characterized in that, In step (2), one or more of the following conditions are included: i. The conductive carbon black dispersion is an ethanol dispersion of conductive carbon black; the concentration of the conductive carbon black dispersion is 2 - 3 g / L; ii. The mass ratio of the conductive carbon black in the conductive carbon black dispersion and the copper salt in step (1) is 2 - 5:1; iii. The sufficient mixing and dispersion is ultrasonic mixing for 1 - 2 h.

9. The application of the non-precious-metal high-entropy alloy lithium-oxygen battery cathode catalyst according to claim 1 or 2, characterized in that, It is applied as a cathode active material to a lithium-oxygen battery.

10. The application according to claim 9, characterized in that, The application method includes the steps: thoroughly grinding and mixing the lithium-oxygen battery cathode catalyst and the binder, adding N-methylpyrrolidone or isopropanol, and dispersing sufficiently to obtain a slurry; then uniformly coating it on carbon paper and drying to obtain the lithium-oxygen battery cathode; preferably, the mass ratio of the lithium-oxygen battery cathode catalyst and the binder is 3 - 5:1; the binder is polytetrafluoroethylene or polyvinylidene fluoride.

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