A multi-doped carbon-based positive electrode material and a preparation method thereof

Abstract

The application relates to the technical field of positive electrode materials, and discloses a multi-element doped carbon-based positive electrode material and a preparation method thereof, which comprises the following steps: mixing a carbon and nitrogen source with a solvent, stirring, and then drying to obtain a precursor material; placing the precursor material in a protective atmosphere for heat treatment to obtain a graphite-like carbon nitride base material; placing the graphite-like carbon nitride base material in a mixed atmosphere for high-temperature doping treatment to obtain a multi-element doped material; carrying out oxidation treatment on the multi-element doped material to obtain an oxidized multi-element doped material; mixing the oxidized multi-element doped material with a cyclodextrin solution, and carrying out ultrasonic treatment to obtain a multi-element doped carbon-based positive electrode material. The nitrogen-sulfur, nitrogen-phosphorus and nitrogen-boron dual-element doping is adopted, an electronic synergistic regulation effect is generated between different heteroatoms, a high-activity dual-doping catalytic site is constructed, the charging reaction catalytic efficiency is significantly improved, the charging polarization is effectively reduced, and the battery reaction kinetics is accelerated.

Description

Technical Field

[0001] This invention relates to the field of cathode material technology, and more specifically, to a multi-component doped carbon-based cathode material and its preparation method. Background Technology

[0002] Carbon-based materials, due to their high conductivity, high specific surface area, tunable pore structure, and excellent chemical stability, are widely used as cathode carriers and electrocatalytic materials in energy storage devices such as lithium-sulfur batteries, metal-air batteries, and aqueous zinc-based batteries. Among them, nitrogen-doped carbon materials prepared using graphitic carbon nitride (C3N4) as a precursor can introduce defective active sites through nitrogen atom doping, thereby improving the electronic conductivity of the carbon framework and the adsorption and catalytic performance of electrochemical reaction intermediates, and have become the mainstream research direction for carbon-based cathode materials.

[0003] Currently, existing technologies mostly focus on carbon-based cathode materials doped with single nitrogen atoms. Although this can improve the catalytic activity and conductivity of carbon materials to some extent, there are still obvious drawbacks: the active sites formed by single nitrogen doping are of limited types and the electronic structure regulation is limited, resulting in insufficient catalytic ability for oxidation reactions during battery charging, leading to excessive charging polarization and slow reaction kinetics; at the same time, the surface active sites of single-doped carbon materials have poor stability, and are prone to site loss and structural collapse during long-term cycling, which in turn leads to rapid capacity decay.

[0004] Some existing technologies attempt to dope carbon materials with single heteroatoms such as sulfur, phosphorus, and boron. While this can introduce new active sites, it fails to create synergistic effects between different heteroatoms, resulting in limited improvements in catalytic activity and failing to fundamentally solve the problems of high charging polarization and poor cycle stability. Furthermore, traditionally doped carbon materials lack effective surface stabilization methods, making it difficult to maintain structural integrity while preserving high catalytic activity, thus limiting their practical application in high-power, long-life energy storage devices.

[0005] Therefore, providing a carbon-based cathode material that can achieve multi-heteroatom synergistic doping, significantly reduce charging polarization, and possess excellent structural stability has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] In view of this, the present invention proposes a multi-component doped carbon-based cathode material and its preparation method, aiming to solve at least one of the problems in the current background technology.

[0007] This invention proposes a method for preparing a multi-element doped carbon-based cathode material, comprising the following steps: (1) The carbon and nitrogen source is mixed with the solvent, stirred and then dried to obtain the precursor material; (2) The precursor material is placed in a protective atmosphere for heat treatment to obtain a graphite-like carbon nitride substrate material; (3) The graphite-like carbon nitride substrate material is placed in a mixed atmosphere for high-temperature doping treatment to obtain a multi-element doped material; (4) The multi-element doped material is oxidized to obtain the oxidized multi-element doped material; (5) The oxidized multi-element doped material is mixed with a cyclodextrin solution and subjected to ultrasonic treatment to obtain the multi-element doped carbon-based cathode material.

[0008] Preferably, the solvent in step (1) is water or ethanol, the carbon and nitrogen source is at least one of melamine, urea, and dicyandiamide, and the ratio of the solvent to the carbon and nitrogen source is 5-20 mL: 1 g.

[0009] Preferably, the protective atmosphere used in step (2) is nitrogen or argon, and the parameters of the heat treatment are: temperature of 500-650℃, time of 2-5 hours, and heating rate of 2-10℃ / min.

[0010] Preferably, the mixed atmosphere in step (3) includes ammonia and at least one doping gas selected from hydrogen sulfide, phosphine, and borane, and the volume ratio of ammonia to doping gas is 1:0.2-0.8; the parameters of the high-temperature doping treatment are: temperature of 600-900℃ and time of 1-4 hours.

[0011] Preferably, the oxidation treatment in step (4) specifically involves placing the multi-element doped material in a 5-10wt% H2O2 solution or dilute nitric acid, refluxing it at a temperature of 60-80℃ for 1-3 hours, washing it until neutral after refluxing, and drying it at a temperature of 60-80℃.

[0012] Preferably, the mass ratio of the oxidized multi-element doped material to the cyclodextrin solution in step (5) is 1:5-20, and the parameters of the ultrasonic treatment are: ultrasonic power 200-500W, ultrasonic time 40-80 minutes.

[0013] Preferably, the cyclodextrin solution in step (5) is selected from at least one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin; the mass fraction of the cyclodextrin solution is 0.5-5%.

[0014] Preferably, in step (5), after the oxidized multi-element doped material is mixed with the cyclodextrin solution, a crosslinking agent is added. The amount of the crosslinking agent added is 0.5-5% of the mass of the oxidized multi-element doped material. The crosslinking agent is selected from at least one of glutaraldehyde, hexachlorocyclotriphosphazene, epichlorohydrin or citric acid.

[0015] The present invention also provides a multi-component doped carbon-based cathode material, which is prepared by the preparation method described in the above technical solution.

[0016] The present invention also provides an application of the multi-doped carbon-based cathode material described in the above technical solution, specifically in the application of cathode materials for lithium-sulfur batteries, metal-air batteries, and aqueous zinc-iodine batteries.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention employs nitrogen-sulfur, nitrogen-phosphorus, and nitrogen-boron dual doping, which generates an electronic synergistic regulation effect between different heteroatoms, constructs highly active dual-doped catalytic sites, significantly improves the catalytic efficiency of charging reaction, effectively reduces charging polarization, and accelerates battery reaction kinetics.

[0018] (2) The present invention introduces oxygen-containing functional groups such as hydroxyl and carboxyl groups on the surface of carbon materials through oxidation treatment, which on the one hand enhances the adsorption capacity of battery intermediate products and suppresses the shuttle effect; on the other hand, it provides stable grafting sites for cyclodextrin and improves the interfacial bonding strength.

[0019] (3) The present invention introduces cyclodextrin coating and fixes it with crosslinking agent to form a cage-like stable structure, which physically anchors the catalytic active site, buffers the volume expansion during charging and discharging, inhibits particle aggregation and structural collapse, and significantly improves long-cycle stability.

[0020] (4) The preparation process of this invention is simple, the conditions are mild, the precursor is readily available, no complex equipment is required, and batch preparation can be stably achieved, making it suitable for the large-scale application of cathode materials for energy storage devices. Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0022] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0025] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0026] This invention provides a method for preparing a multi-element doped carbon-based cathode material, comprising the following steps: (1) The carbon and nitrogen source is mixed with the solvent, stirred and then dried to obtain the precursor material; Specifically, preferably, the solvent in step (1) is water or ethanol, and the carbon-nitrogen source is at least one of melamine, urea, and dicyandiamide. The ratio of solvent to carbon-nitrogen source is 5-20 mL: 1 g, more preferably 10-20 mL: 1 g. The solvent and carbon-nitrogen source are mixed and stirred evenly, and then dried to obtain precursor material powder. The specific drying parameters are not specifically limited, and parameters or technical means known to those skilled in the art can be used.

[0027] This invention mixes and stirs carbon and nitrogen sources with solvents and then dries them, enabling melamine, urea, dicyandiamide, and other carbon and nitrogen sources to be fully dispersed and dissolved in water or ethanol. This achieves a uniform distribution of carbon and nitrogen elements at the molecular scale, forming a solid precursor with uniform composition and no agglomeration. This effectively avoids the problems of component segregation and uneven local reactions that may occur during subsequent heat treatment. At the same time, the solvent is green, volatile, and leaves no impurities, providing a stable and uniform reaction basis for the subsequent generation of graphite-like carbon nitride and heteroatom doping, thus improving the repeatability and consistency of material preparation.

[0028] (2) The precursor material is placed in a protective atmosphere for heat treatment to obtain a graphite-like carbon nitride substrate material; Specifically, preferably, the protective atmosphere uses nitrogen or argon, and the heat treatment parameters are preferably: temperature of 500-650℃, time of 2-5 hours, and heating rate of 2-10℃ / min; more preferably: temperature of 550-600℃, time of 3-4 hours, and heating rate of 4-6℃ / min.

[0029] This invention involves heat-treating the precursor in a nitrogen or argon protective atmosphere, which enables the precursor to undergo directional polycondensation and crystallization, forming a highly crystalline and structurally stable graphitic carbon nitride layered framework. This significantly improves the structural strength and electronic conductivity of the material, while simultaneously creating abundant defect sites and pore structures within the framework. This provides ample anchoring points for the subsequent efficient doping of heteroatoms. The conditions of this step are mild and controllable, and will not damage the basic framework of the precursor. This ensures that the subsequent dual-doping process is uniform and stable, greatly improving the overall structural stability and basic catalytic activity of the material.

[0030] (3) The graphite-like carbon nitride substrate material is placed in a mixed atmosphere for high-temperature doping treatment to obtain a multi-element doped material; Specifically, the mixed atmosphere comprises ammonia and at least one dopant gas selected from hydrogen sulfide, phosphine, and borane. The volume ratio of ammonia to the dopant gas is preferably 1:0.2-0.8, more preferably 1:0.4-0.6. The parameters of the high-temperature doping treatment are preferably: temperature of 600-900℃ and time of 1-4 hours, more preferably: temperature of 700-800℃ and time of 2-3 hours.

[0031] This invention involves high-temperature doping of graphitic carbon nitride in a mixed atmosphere of ammonia, hydrogen sulfide, phosphine, or borane. This allows for simultaneous and efficient lattice doping of nitrogen atoms with sulfur, phosphorus, and boron atoms. Nitrogen atoms can construct conventional catalytic sites such as pyridine N, pyrrole N, and graphitic N, while sulfur, phosphorus, and boron atoms can form synergistic catalytic sites such as NSC, NPC, and NBC with nitrogen atoms. Through interatomic electronic regulation effects, the electronic structure and band distribution of the carbon skeleton are reconstructed, significantly enhancing the catalytic ability for charging reactions, effectively reducing charging polarization, and accelerating electrochemical reaction kinetics. The one-step mixed atmosphere doping process is simple and produces uniform doping, avoiding the structural collapse problem caused by multi-step calcination, and greatly improving the catalytic activity and rate performance of the cathode material.

[0032] (4) The multi-element doped material is oxidized to obtain the oxidized multi-element doped material; The oxidation treatment specifically involves placing the multi-element doped material in a 5-10 wt% H2O2 solution or dilute nitric acid and refluxing it at 60-80℃ for 1-3 hours. After refluxing, the material is washed until neutral and then dried at 60-80℃.

[0033] This invention uses hydrogen peroxide solution or dilute nitric acid to reflux-oxidize multi-element doped materials, which can directionally introduce oxygen-containing functional groups such as carboxyl and hydroxyl groups onto the surface of carbon materials. This significantly improves the hydrophilicity of the material surface and its adsorption capacity for battery reaction intermediates. At the same time, the mild oxidation etching can further expand the material pores and increase the specific surface area. The oxygen-containing functional groups can effectively suppress the shuttle effect and improve the battery cycle stability, and also provide sufficient chemical binding sites for subsequent grafting and fixation of cyclodextrin, strengthening the interfacial bonding strength and achieving the dual effects of surface activation and functional modification.

[0034] (5) The oxidized multi-element doped material is mixed with a cyclodextrin solution. When mixing, the mass ratio of the oxidized multi-element doped material to the cyclodextrin solution is 1:5-20, and the mass ratio is more preferably 1:8-12. Then, ultrasonic treatment is performed. The ultrasonic treatment parameters are preferably: ultrasonic power 200-500W, ultrasonic time 40-80 minutes; more preferably: ultrasonic power 200-500W, ultrasonic time 40-80 minutes, to obtain the multi-element doped carbon-based cathode material.

[0035] The cyclodextrin in the cyclodextrin solution is selected from at least one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin; the mass fraction of the cyclodextrin solution is 0.5-5%.

[0036] More preferably, in step (5), after the oxidized multi-element doped material is mixed with the cyclodextrin solution, i.e. after the ultrasonic treatment is completed, a crosslinking agent is added. The amount of crosslinking agent added is 0.5-5% of the mass of the oxidized multi-element doped material. The crosslinking agent is selected from at least one of glutaraldehyde, hexachlorocyclotriphosphazene, epichlorohydrin or citric acid. After adding the crosslinking agent, the reaction is carried out at 80-120℃ for 4-8 hours to obtain the final multi-element doped carbon-based cathode material.

[0037] This invention involves mixing oxidized doped materials with a cyclodextrin solution, ultrasonicating, and adding a crosslinking agent to react. This allows the cyclodextrin to form a uniform and continuous cage-like coating layer on the material surface. The cyclodextrin can physically anchor the catalytic active sites generated by the doping, buffer the volume expansion during charge and discharge, and inhibit particle aggregation and structural collapse. Combined with the chemical bonding effect of the crosslinking agent, the coating layer can be firmly bonded and will not fall off, significantly improving the structural stability and activity retention of the material during long-cycle processes, further extending battery life, and improving the overall electrochemical performance stability.

[0038] The present invention also provides a multi-component doped carbon-based cathode material, which is prepared by the preparation method described in the above technical solution.

[0039] The present invention also provides an application of the multi-doped carbon-based cathode material described in the above technical solution, specifically in the application of cathode materials for lithium-sulfur batteries, metal-air batteries, and aqueous zinc-iodine batteries.

[0040] Example 1 (1) Weigh 10g of melamine as a carbon and nitrogen source, add 50mL of deionized water, stir at room temperature for 2h until completely dispersed, and dry in an oven at 70℃ until constant weight to obtain a precursor powder with uniform composition. (2) The precursor powder was placed in a tube furnace, and argon gas was introduced into the protective atmosphere. The temperature was increased to 500℃ at 2℃ / min and held for 2h for heat treatment. After natural cooling, a graphite-like carbon nitride substrate material was obtained. (3) The graphite-like carbon nitride substrate material was placed in a tube furnace again, and a mixture of ammonia and hydrogen sulfide in a volume ratio of 5:1 was introduced. The temperature was increased to 600℃ at 7℃ / min and held for 2h for high-temperature doping to obtain nitrogen-sulfur dual-doped carbon material.

[0041] (4) Add nitrogen-sulfur dual-doped carbon material to 5wt% hydrogen peroxide solution, reflux at 60℃ for 1h, cool and wash with deionized water until neutral, and vacuum dry at 70℃.

[0042] (5) Take 3g of oxidized double-doped material, add 0.5% β-cyclodextrin aqueous solution (containing 0.6g β-cyclodextrin), ultrasonically disperse at 300W power for 60min, add 0.06g epichlorohydrin as crosslinking agent, heat to 100℃ and react for 6h, and obtain nitrogen-sulfur double-doped carbon-based cathode material after washing and drying.

[0043] Example 2 (1) Weigh 10g of melamine as a carbon and nitrogen source, add 100mL of deionized water, stir at room temperature for 2h until completely dispersed, and dry in an oven at 70℃ until constant weight to obtain a precursor powder with uniform composition. (2) The precursor powder was placed in a tube furnace, and argon gas was introduced into the protective atmosphere. The temperature was increased to 550°C at 4°C / min and held for 4 hours for heat treatment. After natural cooling, a graphite-like carbon nitride substrate material was obtained. (3) The graphite-like carbon nitride substrate material was placed in a tube furnace again, and a mixture of ammonia and hydrogen sulfide in a volume ratio of 5:3 was introduced. The temperature was increased to 700℃ at 7℃ / min and held for 2 hours for high-temperature doping to obtain nitrogen-sulfur dual-doped carbon material.

[0044] (4) Add the nitrogen-sulfur dual-doped carbon material to an 8wt% hydrogen peroxide solution, reflux at 70°C for 2 hours, cool and wash with deionized water until neutral, and vacuum dry at 70°C.

[0045] (5) Take 3g of oxidized double-doped material, add 2% β-cyclodextrin aqueous solution (containing 0.9g β-cyclodextrin), ultrasonically disperse at 300W power for 60min, add 0.06g epichlorohydrin as crosslinking agent, heat to 100℃ and react for 6h, and obtain nitrogen-sulfur double-doped carbon-based cathode material after washing and drying.

[0046] Example 3 (1) Weigh 10g of melamine as a carbon and nitrogen source, add 200mL of deionized water, stir at room temperature for 2h until completely dispersed, and dry in an oven at 70℃ until constant weight to obtain a precursor powder with uniform composition. (2) The precursor powder was placed in a tube furnace, and argon gas was introduced to provide a protective atmosphere. The temperature was increased to 550°C at 5°C / min and held for 3 hours for heat treatment. After natural cooling, a graphite-like carbon nitride substrate material was obtained. (3) The graphite-like carbon nitride substrate material was placed in a tube furnace again, and a mixture of ammonia and hydrogen sulfide in a volume ratio of 5:4 was introduced. The temperature was increased to 800°C at 7°C / min and held for 4 hours for high-temperature doping to obtain nitrogen-sulfur dual-doped carbon material.

[0047] (4) Add the nitrogen-sulfur dual-doped carbon material to a 10wt% hydrogen peroxide solution, reflux at 80℃ for 3h, cool and wash with deionized water until neutral, and vacuum dry at 70℃.

[0048] (5) Take 3g of oxidized double-doped material, add 5% β-cyclodextrin aqueous solution (containing 0.7g β-cyclodextrin), ultrasonically disperse at 300W power for 60min, add 0.06g epichlorohydrin as crosslinking agent, heat to 100℃ and react for 6h, and obtain nitrogen-sulfur double-doped carbon-based cathode material after washing and drying.

[0049] Comparative Example 1 (1) Weigh 10g of melamine, add 100mL of deionized water, stir at room temperature for 2h, and dry at 70℃ to constant weight to obtain precursor powder.

[0050] (2) The precursor was placed in a tube furnace and argon gas was introduced to create a protective atmosphere. The temperature was increased to 550°C at 5°C / min, held for 3 hours, and then naturally cooled to obtain a graphite-like carbon nitride substrate material.

[0051] (3) The graphite-like carbon nitride substrate material was purged with pure ammonia gas and heated to 700°C at 7°C / min. The temperature was then maintained for 2 hours for single doping treatment to obtain a single nitrogen-doped carbon material.

[0052] (4) Add the nitrogen-doped carbon material to an 8 wt% hydrogen peroxide solution, reflux at 70°C for 2 h, wash until neutral, and vacuum dry at 70°C.

[0053] (5) Take 3g of the oxidized material, add an aqueous solution containing 1.2g of β-cyclodextrin, sonicate at 300W for 60min, add 0.06g of epichlorohydrin, react at 100℃ for 6h, wash and dry to obtain a single nitrogen-doped carbon-based cathode material.

[0054] Comparative Example 2 The precursor preparation, graphite-like carbon nitride preparation, nitrogen-sulfur dual doping, and oxidation treatment steps are exactly the same as in Example 1. The only difference is that 3g of oxidized nitrogen-sulfur dual-doped carbon material is taken, without adding cyclodextrin and crosslinking agent, and directly dried as nitrogen-sulfur dual-doped carbon-based cathode material without cyclodextrin fixation.

[0055] Performance testing The materials obtained in Examples 1-3 and Comparative Examples 1-2 were used as positive electrode active materials and mixed uniformly with conductive carbon black and polyvinylidene fluoride (PVDF) at a mass ratio of 8:1:1. This mixture was then coated onto an aluminum foil current collector and assembled into a CR2032 type coin-type lithium-sulfur battery. A lithium metal sheet was used as the negative electrode, and a polypropylene porous membrane was used as the separator. The battery was encapsulated in an argon atmosphere glove box. Constant current charge-discharge tests were performed using a Blue Battery testing system under the following conditions: Voltage range: 1.7~2.8V vs Li / Li+ Charging polarization test: current density 1mA / cm 2 Initial discharge specific capacity: current density 0.2C Cyclic stability: 0.5C current density, 100 cycles Rate performance: Current densities 0.2C, 0.5C, 1C, 2C The results of the above tests are shown in Table 1: Table 1 Test Results Based on Table 1, it can be seen that the charging polarization of Examples 1-3 of the present invention is much lower than that of Comparative Example 1, indicating that the nitrogen-sulfur dual doping of the present invention produces a synergistic catalytic effect, effectively solving the technical problems of single nitrogen doping active sites, excessive charging polarization, and slow reaction kinetics, and significantly reducing charging polarization and accelerating the electrochemical reaction rate.

[0056] Furthermore, the higher initial discharge specific capacity of Examples 1-3 indicates that the dual-doped structure of the present invention can increase the number of catalytic active sites, enhance the adsorption and catalytic conversion ability of reaction intermediates, and improve the effective capacity of the battery. Also, the capacity retention rate of Examples 1-3 after 100 cycles is significantly better than that of Comparative Examples 1 and 2, demonstrating that the oxidation treatment and cyclodextrin coating crosslinking fixation of the present invention can stabilize active sites and inhibit structural collapse, solving the problems of site loss and rapid capacity decay in traditional carbon-doped materials during cycling. In addition, the superior rate performance of Examples 1-3 indicates that the synergistic effect of dual doping and the cyclodextrin-stabilized structure of the present invention jointly improve the conductivity and structural stability of the material, meeting the requirements for high-power energy storage devices.

[0057] As can be seen from the above, the technical solution of the present invention can simultaneously achieve low charging polarization, high specific capacity, long cycle stability and excellent rate performance.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a multi-component doped carbon-based cathode material, characterized in that, Includes the following steps: (1) The carbon and nitrogen source is mixed with the solvent, stirred and then dried to obtain the precursor material; (2) The precursor material is placed in a protective atmosphere for heat treatment to obtain a graphite-like carbon nitride substrate material; (3) The graphite-like carbon nitride substrate material is placed in a mixed atmosphere for high-temperature doping treatment to obtain a multi-element doped material; (4) The multi-element doped material is oxidized to obtain the oxidized multi-element doped material; (5) The oxidized multi-element doped material is mixed with a cyclodextrin solution and subjected to ultrasonic treatment to obtain the multi-element doped carbon-based cathode material.

2. The method for preparing the multi-component doped carbon-based cathode material according to claim 1, characterized in that, The solvent in step (1) is water or ethanol, and the carbon and nitrogen source is at least one of melamine, urea, and dicyandiamide. The ratio of the amount of solvent to carbon and nitrogen source is 5-20 mL: 1 g.

3. The method for preparing the multi-component doped carbon-based cathode material according to claim 1, characterized in that, The protective atmosphere used in step (2) is nitrogen or argon, and the parameters of the heat treatment are: temperature of 500-650℃, time of 2-5 hours, and heating rate of 2-10℃ / min.

4. The method for preparing the multi-component doped carbon-based cathode material according to claim 1, characterized in that, The mixed atmosphere in step (3) includes ammonia and at least one doping gas selected from hydrogen sulfide, phosphine, and borane, with the volume ratio of ammonia to doping gas being 1:0.2-0.8; the parameters for the high-temperature doping treatment are: temperature of 600-900℃ and time of 1-4 hours.

5. The method for preparing the multi-component doped carbon-based cathode material according to claim 1, characterized in that, The oxidation treatment in step (4) is as follows: the multi-element doped material is placed in a 5-10wt% H2O2 solution or dilute nitric acid and refluxed at a temperature of 60-80℃ for 1-3 hours. After reflux, it is washed until neutral and dried at a temperature of 60-80℃.

6. The method for preparing the multi-component doped carbon-based cathode material according to claim 1, characterized in that, The mass ratio of the oxidized multi-element doped material to the cyclodextrin solution in step (5) is 1:5-20, and the parameters of the ultrasonic treatment are: ultrasonic power 200-500W, ultrasonic time 40-80 minutes.

7. The method for preparing the multi-component doped carbon-based cathode material according to claim 1, characterized in that, The cyclodextrin solution in step (5) is selected from at least one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin; the mass fraction of the cyclodextrin solution is 0.5-5%.

8. The method for preparing the multi-component doped carbon-based cathode material according to claim 1, characterized in that, In step (5), after the oxidized multi-element doped material is mixed with the cyclodextrin solution, a crosslinking agent is added. The amount of the crosslinking agent added is 0.5-5% of the mass of the oxidized multi-element doped material. The crosslinking agent is selected from at least one of glutaraldehyde, hexachlorocyclotriphosphazene, epichlorohydrin or citric acid.

9. A multi-component doped carbon-based cathode material, characterized in that, The multi-doped carbon-based cathode material is prepared by the preparation method described in any one of claims 1-8.

10. An application of the multi-component doped carbon-based cathode material according to claim 9, characterized in that, The specific applications are in the cathode materials of lithium-sulfur batteries, metal-air batteries, and aqueous zinc-iodine batteries.

Images