Fe and N co-doped flower-shaped structure carbon material and preparation method thereof
By preparing Fe and N co-doped flower-structured carbon materials, the problems of metal agglomeration and low doping amount were solved, the electrochemical performance of Li-S batteries was improved, and efficient membrane modification effects were achieved.
Patent Information
- Application Number
- CN202510838448.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-23
- Publication Date
- 2025-09-16
AI Technical Summary
In the prior art, during the preparation of Fe and N co-doped carbon materials, metal atoms easily agglomerate, the morphology is unstable, and the doping amount is low, which limits the overall performance improvement of Li-S batteries.
Zinc gluconate was used as the carbon and zinc sources, FeCl3 as the iron source, and formamide as the nitrogen source. Fe and N co-doped flower-structured carbon materials were prepared by solvent thermal reaction and calcination. The doping amount and morphology of Fe and N were controlled to avoid metal agglomeration, form stable C/N bonds, and optimize the material structure.
Highly dispersed doping of Fe and N atoms is achieved, which improves the electrochemical performance of Li-S batteries, especially the rate and long cycle performance of the diaphragm modified material. The material is low-cost and environmentally friendly.
Smart Images
Figure CN120646806A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalysts, and in particular to an Fe and N co-doped flower-shaped carbon material and a preparation method thereof. Background Art
[0002] In recent years, the rapid development of smart communications devices and electric vehicles has spurred the development of next-generation rechargeable batteries, particularly new batteries with high energy density and lower costs. Among the many new battery systems being developed, lithium-sulfur (Li-S) secondary batteries, constructed with elemental sulfur as the positive electrode and metallic lithium as the negative electrode, boast a theoretical energy density of up to 2600 Wh / kg, far exceeding that of currently commercialized lithium-ion batteries. Furthermore, sulfur, with its abundant reserves, low cost, and environmental friendliness, is considered a promising candidate for the next generation of high-energy-density energy storage systems and has become a hot topic of research (Adv. Energy Mater, 2025, 2405890).
[0003] However, the Li-S battery system still faces many scientific problems, including: ① poor conductivity of elemental sulfur; ② the long-chain lithium polysulfide (Li2S x ) dissolves in the electrolyte, diffuses through the diaphragm to the negative electrode and reacts with it to form short-chain lithium polysulfide. Subsequently, some short-chain lithium polysulfide diffuses to the positive electrode area and is oxidized to become long-chain lithium polysulfide. This cycle leads to the formation of a "shuttle effect"; ③ The reaction kinetics of soluble long-chain lithium polysulfide converted into solid-phase Li2S2 / Li2S are slow, which hinders the reaction. The interaction and influence of these factors have seriously restricted the comprehensive performance improvement of Li-S batteries and the development of practical battery systems (Small, 2024, 20, 2309146.). To this end, researchers have also proposed a variety of improvement plans, among which diaphragm modification is one of the effective methods to improve the performance of Li-S batteries.
[0004] Using carbon materials to modify the separator is a common method. The carbon coating not only has excellent conductivity, but also has a developed pore structure that can adsorb Li2S x , hindering Li2S x However, pure carbonaceous materials and Li2S x The physical adsorption between them is weak, and it is difficult to effectively anchor polar Li2S during long cycles. x Furthermore, the researchers increased the polar sites of carbon materials by doping heterogeneous atoms (such as N, S, etc.) to improve the carbon-based materials and Li2S xThe interaction between the carbon matrix and the carbon substrate effectively suppresses the “shuttle effect.” Although the polarity of the carbon matrix can be effectively improved by introducing heteroatoms, the current heteroatom doping level is generally low. Even if the doping level can be increased through special design, high doping levels will reduce the conductivity of the carbon material and cause structural instability (Electrochim. Acta, 2024, 496, 144487.).
[0005] Studies have shown that highly dispersed metal atoms (such as Fe, Co, Ni, etc.)-nitrogen atoms co-doped carbon materials (MNCs) have abundant active sites, which can not only significantly adsorb the intermediate product lithium polysulfide, but also accelerate the redox conversion of lithium polysulfide, improve the conversion kinetics of sulfur, and enhance the electrical performance of Li-S batteries (J.Energy Chem., 2022, 73, 513-532.). Generally, the preparation of MNCs materials is obtained by cracking a mixture of metal salts, nitrogen sources and carbon sources and post-treatment (acid washing). However, during the high-temperature calcination process, it is difficult to avoid the agglomeration of the metal and the irregularity of the morphology, and the active sites cannot be exposed, which is not conducive to the high performance of the material; in addition, the preparation method usually obtains a low Fe atom doping amount. How to further improve the comprehensive performance of metal atom-nitrogen atom co-doped carbon materials is a difficult problem faced by this field.
[0006] In summary, there is an urgent need to develop a new technical solution to address the deficiencies in the existing technology. Summary of the Invention
[0007] Based on this, the present invention provides an Fe-N co-doped flower-structured carbon material and a preparation method thereof. The present invention uses zinc gluconate as the carbon and zinc sources, FeCl3 as the iron source, and formamide solvent as the nitrogen source to prepare a highly dispersed iron-nitrogen atom co-doped flower-structured carbon material. By adjusting the ratio of zinc gluconate to FeCl3, the present invention effectively controls the flower-like structure and Fe-N doping. Furthermore, the process is simple, the raw materials are inexpensive, and the material is environmentally friendly. The Fe and N doping levels and morphology of the resulting material are controllable, overcoming the shortcomings of existing technologies and demonstrating great application potential and value.
[0008] The object of the present invention is to provide an Fe, N co-doped flower-like structure carbon material, wherein the Fe, N co-doped flower-like structure carbon material has a spherical structure, and a plurality of the spherical structures form a flower-like structure;
[0009] The Fe and N co-doped flower-shaped carbon material consists of C, N, O and Fe elements.
[0010] Furthermore, the atomic percentage of C is 80-90%; the atomic percentage of N is 1-5%; the atomic percentage of O is 1-10%; and the atomic percentage of Fe is 0.1-1%.
[0011] Furthermore, the particle size of the spherical structure is 0.1-10 μm.
[0012] Furthermore, the Fe, N co-doped flower-like structure carbon material is prepared by solvent thermal reaction of zinc gluconate, ferric chloride and formamide to obtain a precursor, which is then calcined and washed to obtain the Fe, N co-doped flower-like structure carbon material.
[0013] Another object of the present invention is to provide a method for preparing the above-mentioned Fe, N co-doped flower-like structure carbon material, wherein the method for preparing the Fe, N co-doped flower-like structure carbon material comprises the following steps:
[0014] S1. Add zinc gluconate and ferric chloride to formamide, stir and dissolve them, and then perform a solvothermal reaction to obtain a precursor;
[0015] S2. Under the protection of an inert gas, calcining the precursor to obtain an intermediate product;
[0016] S3. Wash the intermediate product to obtain the Fe and N co-doped flower-like structure carbon material.
[0017] Furthermore, the molar ratio of the zinc gluconate to the ferric chloride is 3:(0.083-0.666).
[0018] Furthermore, the molar volume ratio of the zinc gluconate to formamide is 0.01-0.1 mmol / mL.
[0019] Preferably, the molar dosage of the zinc gluconate is 3 mmoL, and the molar dosage of the ferric chloride is 0.083-0.666 mmoL.
[0020] More preferably, the molar ratio of zinc gluconate to ferric chloride is 3:0.083, 3:0.166, 3:0.333 or 3:0.666.
[0021] Most preferably, the molar dosage of the zinc gluconate is 3 mmoL, and the molar dosage of the ferric chloride is 0.333 mmoL.
[0022] Preferably, the amount of formamide used is 50 mL.
[0023] Furthermore, the solvent thermal reaction temperature is 150-200° C., and the time is 6-24 hours.
[0024] Preferably, the temperature of the solvent thermal reaction is 180° C. and the time is 12 h.
[0025] Furthermore, the calcination temperature is 800-1000° C. and the calcination time is 1-3 hours.
[0026] Preferably, the calcination temperature is 900° C., the calcination time is 2 h, and the heating rate is 5° C. / min.
[0027] Furthermore, the washing comprises: washing with a sulfuric acid solution having a concentration of 1-4 mol / L at 60-100°C.
[0028] Preferably, the washing is as follows: mixing the intermediate product with a 2 mol / L sulfuric acid solution, magnetically stirring at 80°C for 12 hours, filtering to obtain a black substance, washing with water until the filtrate is neutral, and vacuum drying at 50°C to obtain the Fe, N co-doped flower-like structure carbon material.
[0029] The present invention has the following beneficial effects:
[0030] (1) The present invention uses cheap zinc gluconate as a carbon source and zinc source, FeCl3 as an iron source, and formamide as a nitrogen source and reaction solvent, and utilizes the amino and carbonyl groups of formamide itself to undergo a Schiff base reaction under high temperature conditions to form a molecular chain containing rich C / N bonds, and further chelates metal ions to effectively stabilize metal atoms, thereby obtaining a precursor based on the complex Zn2Fe(CN)6, thereby avoiding the agglomeration of Fe, promoting and ensuring the high dispersion doping of Fe and N atoms; subsequently, the final product is obtained by high-temperature calcination and acid washing treatment, and the Zn element is evaporated and dissolved, and in the calcination process, the evaporation of Zn is conducive to the formation of a porous structure, thereby further improving and optimizing the structure of the product.
[0031] (2) The present invention can achieve the formation of flower-like morphology of MNCs materials and effective control of Fe and N doping amounts by adjusting the ratio of raw materials and calcination conditions.
[0032] (3) The raw materials of the present invention are inexpensive and environmentally friendly, the preparation process of the precursor is simple, and it can be prepared without purchasing special processing equipment, and has good compatibility with the existing carbon material industrial production process. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 This is the XRD pattern of the precursor obtained in step S1 of Example 1-4.
[0034] Figure 2 This is the XRD pattern of the Fe and N co-doped flower-structured carbon material prepared in Example 1-4.
[0035] Figure 3 This is the XPS graph of the Fe and N co-doped flower-structured carbon material prepared in Example 3.
[0036] Figure 4 This is the fine spectrum of N and Fe elements of the Fe, N co-doped flower-structured carbon material prepared in Example 3;
[0037] in, Figure 4 (a) is the fine spectrum of N element; Figure 4 (b) is the fine spectrum of Fe element.
[0038] Figure 5 These are SEM images of the precursor and Fe, N co-doped flower-structured carbon materials prepared in comparative example.
[0039] Figure 6 These are SEM images of the precursor and Fe, N co-doped flower-structured carbon materials prepared in Examples 1-4.
[0040] Figure 7 This is a rate performance diagram of the Fe and N co-doped flower-structured carbon material prepared in Example 3 as a membrane modification material.
[0041] Figure 8 This is a graph showing the 400-cycle long-cycle performance of the Fe and N co-doped flower-structured carbon material prepared in Example 3 as a diaphragm modification material.
[0042] Figure 9 This is a rate performance diagram of the Fe and N co-doped flower-structured carbon material prepared in comparative example as a diaphragm modification material.
[0043] Figure 10 This is a graph showing the 400-cycle long-cycle performance of the Fe and N co-doped flower-structured carbon material prepared in the comparative example as a diaphragm modification material. DETAILED DESCRIPTION
[0044] In order to more clearly illustrate the technical solutions of the present invention, the following examples are given. Unless otherwise stated, the raw materials, reactions and post-processing methods mentioned in the examples are common raw materials on the market and technical methods well known to those skilled in the art.
[0045] The terms "preferred," "preferably," "more preferred," and the like, used herein, refer to embodiments of the invention that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.
[0046] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties to be obtained by the present invention.
[0047] Example 1
[0048] S1. Weigh 3 mmol zinc gluconate and 0.083 mmol FeCl3 into a beaker, add 50 mL formamide solvent, and stir ultrasonically for 30 minutes until they are dissolved into a uniform solution; then transfer to a reactor and react in an oven at 180°C for 12 hours; after the reaction is complete, cool to room temperature, filter, wash, and dry to obtain a precursor;
[0049] S2, collecting the precursor into a porcelain boat and sending it into a tube furnace, introducing argon protective gas, heating it to 900° C. at a heating rate of 5° C. / min and keeping it at this temperature for 2 h, and then naturally cooling it to room temperature to obtain an intermediate product;
[0050] S3. After grinding the intermediate product, transfer it into a 100 mL round-bottom flask, add 50 mL of 2.0 mol / L dilute sulfuric acid, and magnetically stir at 80°C for 12 h. Then filter out the black substance, wash with water until the filtrate is neutral (filtrate pH = 7), and dry it in a vacuum drying oven at 50°C overnight to obtain the Fe, N co-doped flower-like structure carbon material.
[0051] The atomic percentages of C, N, O and Fe in the Fe and N co-doped flower-structured carbon material are 86.14 at %, 4.75 at %, 8.83 at % and 0.28 at %, respectively.
[0052] Example 2
[0053] S1. Weigh 3 mmol zinc gluconate and 0.166 mmol FeCl3 into a beaker, add 50 mL formamide solvent, and stir ultrasonically for 30 minutes until they dissolve into a uniform solution; then transfer to a reactor and react in an oven at 180°C for 12 hours; after the reaction is complete, cool to room temperature, filter, wash, and dry to obtain a precursor;
[0054] S2, collecting the precursor into a porcelain boat and sending it into a tube furnace, introducing argon protective gas, heating it to 900° C. at a heating rate of 5° C. / min and keeping it at this temperature for 2 h, and then naturally cooling it to room temperature to obtain an intermediate product;
[0055] S3. After grinding the intermediate product, transfer it into a 100 mL round-bottom flask, add 50 mL of 2.0 mol / L dilute sulfuric acid, and magnetically stir at 80°C for 12 h. Then filter out the black substance, wash with water until the filtrate is neutral (filtrate pH = 7), and dry it in a vacuum drying oven at 50°C overnight to obtain the Fe, N co-doped flower-like structure carbon material.
[0056] The atomic percentages of C, N, O and Fe in the Fe and N co-doped flower-structured carbon material are 86.45 at %, 4.53 at %, 8.69 at % and 0.33 at %, respectively.
[0057] Example 3
[0058] S1. Weigh 3 mmol zinc gluconate and 0.333 mmol FeCl3 into a beaker, add 50 mL formamide solvent, and stir ultrasonically for 30 minutes until it dissolves into a uniform solution; then transfer to a reactor and react in an oven at 180°C for 12 hours; after the reaction is complete, cool to room temperature, filter, wash, and dry to obtain a precursor;
[0059] S2, collecting the precursor into a porcelain boat and sending it into a tube furnace, introducing argon protective gas, heating it to 900° C. at a heating rate of 5° C. / min and keeping it at this temperature for 2 h, and then naturally cooling it to room temperature to obtain an intermediate product;
[0060] S3. After grinding the intermediate product, transfer it into a 100 mL round-bottom flask, add 50 mL of 2.0 mol / L dilute sulfuric acid, and magnetically stir at 80°C for 12 h. Then filter out the black substance, wash with water until the filtrate is neutral (filtrate pH = 7), and dry it in a vacuum drying oven at 50°C overnight to obtain the Fe, N co-doped flower-like structure carbon material.
[0061] The atomic percentages of C, N, O and Fe in the Fe and N co-doped flower-structured carbon material are 86.32 at %, 4.53 at %, 8.69 at % and 0.46 at %, respectively.
[0062] Example 4
[0063] S1. Weigh 3 mmol zinc gluconate and 0.666 mmol FeCl3 into a beaker, add 50 mL formamide solvent, and stir ultrasonically for 30 minutes until they are dissolved into a uniform solution; then transfer to a reactor and react in an oven at 180°C for 12 hours; after the reaction is complete, cool to room temperature, filter, wash, and dry to obtain a precursor;
[0064] S2, collecting the precursor into a porcelain boat and sending it into a tube furnace, introducing argon protective gas, heating it to 900° C. at a heating rate of 5° C. / min and keeping it at this temperature for 2 h, and then naturally cooling it to room temperature to obtain an intermediate product;
[0065] S3. After grinding the intermediate product, transfer it into a 100 mL round-bottom flask, add 50 mL of 2.0 mol / L dilute sulfuric acid, and magnetically stir at 80°C for 12 h. Then filter out the black substance, wash with water until the filtrate is neutral (filtrate pH = 7), and dry it in a vacuum drying oven at 50°C overnight to obtain the Fe, N co-doped flower-like structure carbon material.
[0066] The atomic percentages of C, N, O and Fe in the Fe and N co-doped flower-structured carbon material are 86.03 at %, 4.94 at %, 8.52 at % and 0.51 at %, respectively.
[0067] Comparative Example
[0068] The difference between this comparative example and Example 3 is that step S1 is modified as follows:
[0069] S1. Weigh 3 mmol glucose, 3 mmol ZnCl2, and 0.333 mmol FeCl3 into a beaker, add 50 mL formamide solvent, and stir ultrasonically for 30 minutes until it dissolves into a uniform solution; then transfer to a reactor and react in an oven at 180°C for 12 hours; after the reaction is complete, cool to room temperature, filter, wash, and dry to obtain a precursor;
[0070] Other components and steps are the same as those in Example 3.
[0071] Test Case
[0072] Test method:
[0073] (1) The Fe and N co-doped flower-structured carbon materials prepared in Examples 1-4 and the comparative example were characterized.
[0074] (2) Using the Fe and N co-doped flower-like carbon materials prepared in Example 3 and the comparative example as the separator modification material, a button cell was assembled with metallic lithium as the negative electrode and a sulfur / carbon material as the positive electrode (see Chem. Eng. J., 2021, 415, 129001). The device performance was tested.
[0075] The test results are as follows Figure 1-10 shown.
[0076] Figure 1 This is the XRD pattern of the precursor obtained in step S1 of Example 1-4.
[0077] Figure 2 This is the XRD pattern of the Fe and N co-doped flower-structured carbon material prepared in Example 1-4.
[0078] Figure 3 This is the XPS graph of the Fe and N co-doped flower-structured carbon material prepared in Example 3.
[0079] Figure 4 This is the fine spectrum of N and Fe elements of the Fe, N co-doped flower-structured carbon material prepared in Example 3;
[0080] in, Figure 4 (a) is the fine spectrum of N element; Figure 4 (b) is the fine spectrum of Fe element.
[0081] Figure 5 These are SEM images of the precursor and Fe, N co-doped flower-structured carbon materials prepared in comparative example.
[0082] Figure 6 These are SEM images of the precursor and Fe, N co-doped flower-structured carbon materials prepared in Examples 1-4.
[0083] Figure 7 This is a rate performance diagram of the Fe and N co-doped flower-structured carbon material prepared in Example 3 as a membrane modification material.
[0084] Figure 8 This is a graph showing the 400-cycle long-cycle performance of the Fe and N co-doped flower-structured carbon material prepared in Example 3 as a diaphragm modification material.
[0085] Figure 9 This is a rate performance diagram of the Fe and N co-doped flower-structured carbon material prepared in comparative example as a diaphragm modification material.
[0086] Figure 10 This is a graph showing the 400-cycle long-cycle performance of the Fe and N co-doped flower-structured carbon material prepared in the comparative example as a diaphragm modification material.
[0087] according to Figure 1 It can be seen that with the addition of FeCl3, the diffraction peak of the complex Zn2Fe(CN)6 appears in the precursor, and with the increase of the amount of FeCl3 added, the intensity of the diffraction peak also increases, indicating that the condensation reaction of formamide molecules in the solvent thermal process forms a molecular chain containing rich C / N bonds, and further chelates the metal Zn 2+ with Fe 3+ ions, forming a complex Zn2Fe(CN)6, which effectively stabilizes the metal atoms.
[0088] according to Figure 2 As can be seen, when the FeCl3 addition amounts were 0.083, 0.166, and 0.333 mmol, two typical broad peaks of carbon appeared in the resulting product. When the addition amount was increased to 0.666 mmol, characteristic diffraction peaks of Fe / Fe3C appeared in the resulting product. These results indicate that the amount of iron source significantly affects the composition of the product.
[0089] according to Figure 3 It can be seen that when the addition amount of FeCl3 is 0.333 mmol, the obtained product contains C, N, O, and Fe elements, indicating that the preparation method of the present invention can achieve Fe and N co-doped carbon materials.
[0090] according to Figure 4 It can be seen that the present invention can achieve co-doping of N and Fe atoms, and can also adjust the composition of the obtained material by changing the content of the iron source.
[0091] according to Figure 5 It can be seen that the precursor prepared in the comparative example and the calcined product both exhibit irregular spherical structures, and the size of the calcined product is about 1 μm. This may be due to the excessive chlorine introduced into the zinc chloride affecting the morphology and structure of the product.
[0092] according to Figure 6 It can be seen that with the addition of FeCl3, an obvious flower-like structure is formed during the solvent thermal process, which should be the Fe 3+ 、Zn 2+ The ions coordinate with the polymerized polyformamide molecules to form a complex. After calcination, when the FeCl3 addition level is not high, the flower-like structure morphology is still maintained; when the addition level is too high, a tubular structure is generated. This is because the high content of metal can catalyze the formation of carbon nanotube structures under high temperature conditions.
[0093] according to Figure 7 、 8 It can be seen that the lithium-sulfur battery assembled with the separator modified with this material can discharge up to about 1190 mAh / g at a 0.2C rate, and after 400 cycles at a 0.5C rate, the capacity retention rate can still reach about 67%, showing stable rate and cycle performance.
[0094] according to Figure 9 、 10 It can be seen that the electrochemical catalytic performance of the Fe, N co-doped flower-structured carbon material prepared by replacing zinc gluconate with glucose and zinc chloride is not ideal, and the device performance is significantly reduced.
[0095] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.
[0096] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.
Claims
1. An Fe and N co-doped flower-like carbon material, characterized in that: The Fe and N co-doped flower-shaped carbon material has a spherical structure, and a plurality of the spherical structures form a flower-shaped structure; The Fe and N co-doped flower-shaped carbon material consists of C, N, O and Fe elements.
2. The Fe and N co-doped flower-like carbon material according to claim 1, characterized in that: The atomic percentage of C is 80-90%; the atomic percentage of N is 1-5%; the atomic percentage of O is 1-10%; and the atomic percentage of Fe is 0.1-1%.
3. The Fe and N co-doped flower-like carbon material according to claim 1, characterized in that: The particle size of the spherical structure is 0.1-10 μm.
4. The Fe and N co-doped flower-like carbon material according to claim 1, characterized in that: The Fe, N co-doped flower-like structure carbon material is prepared by solvent thermal reaction of zinc gluconate, ferric chloride and formamide to obtain a precursor, which is then calcined and washed to obtain the Fe, N co-doped flower-like structure carbon material.
5. The method for preparing the Fe and N co-doped flower-like carbon material according to any one of claims 1 to 4, characterized in that: The preparation method of the Fe and N co-doped flower-shaped carbon material comprises the following steps: S1. Add zinc gluconate and ferric chloride to formamide, stir and dissolve them, and then perform a solvothermal reaction to obtain a precursor; S2. Under the protection of an inert gas, calcining the precursor to obtain an intermediate product; S3. Wash the intermediate product to obtain the Fe and N co-doped flower-like structure carbon material.
6. The method for preparing the Fe and N co-doped flower-like structure carbon material according to claim 5, characterized in that: The molar ratio of the zinc gluconate to the ferric chloride is 3:(0.083-0.666).
7. The method for preparing the Fe and N co-doped flower-like carbon material according to claim 5, characterized in that: The molar volume ratio of the zinc gluconate to formamide is 0.01-0.1 mmol / mL.
8. The method for preparing the Fe and N co-doped flower-like carbon material according to claim 5, characterized in that: The temperature of the solvent thermal reaction is 150-200° C., and the time is 6-24 hours.
9. The method for preparing the Fe and N co-doped flower-like carbon material according to claim 5, characterized in that: The calcination temperature is 800-1000° C. and the calcination time is 1-3 hours.
10. The method for preparing the Fe and N co-doped flower-like carbon material according to claim 5, characterized in that: The washing comprises: washing with a sulfuric acid solution having a concentration of 1-4 mol / L at 60-100°C.