A three-dimensional hierarchical porous carbon network material, its preparation method and application

Abstract

The present application discloses a three-dimensional hierarchical porous carbon network material, a preparation method thereof and an application thereof, relating to the field of synthesis of porous materials. The method includes: dispersing a surfactant containing cetyltrimethylammonium cation CTA + and triethanolamine in water, adding a tetraethyl orthosilicate / cyclohexane solution, carrying out a stirring reaction, separating and purifying, and collecting wrinkled mesoporous SiO2 nanospheres; dispersing the wrinkled mesoporous SiO2 nanospheres, a nitrogen-containing carbon source monomer, phytic acid, a non-ionic surfactant and an initiator in water for reaction to obtain a mesoporous SiO2@polymer composite material; subjecting the composite material to high-temperature carbonization in an inert gas atmosphere, dispersing it in an aqueous sodium hydroxide solution for etching, separating and purifying, and thus obtaining the three-dimensional hierarchical porous carbon network material. In this way, the material can have the characteristics of N, O and P triple doping and a high specific surface area, and the pore size is easy to control. When applied to the negative electrode of a lithium-ion battery, it exhibits high capacity and long life, and is expected to be widely used in the field of lithium-ion batteries.

Description

Technical Field

[0001] This application relates to the field of synthesis of porous materials, and particularly to a three-dimensional hierarchical porous carbon network material, a preparation method thereof, and an application thereof. Background Art

[0002] Porous carbon materials have become a research hotspot in the current energy materials and chemical engineering fields due to their high porosity, good electrical conductivity, excellent mechanical properties, and stable structure and physicochemical properties. Among them, hierarchical porous carbon materials, as a new type of porous carbon materials, have a structure composed of interconnected micropores (<2 nm), mesopores (2 - 50 nm), and macropores (>50 nm) at different scales, and have extremely high porosity. Micropores can significantly increase the specific surface area of the material and provide abundant active sites, mesopores are beneficial to the diffusion of reactants or solvents, and macropores provide unobstructed interfacial contact to relieve volume changes to maintain structural stability. These characteristics endow hierarchical porous carbon materials with great application potential in the field of electrochemical energy storage and conversion.

[0003] According to the different mechanisms of pore structure formation, the current preparation methods of hierarchical porous carbon materials are mainly divided into the following three types: hard template method, soft template method, and direct carbonization method. Each method has its own advantages and corresponding defects. The hard template method is the most commonly used method for synthesizing hierarchical porous carbon materials, and its nano-morphology and pore structure can be precisely designed and regulated. However, its preparation process is cumbersome, including steps such as template synthesis, precursor filling, and template removal, and usually requires surface modification of the template to promote uniform filling of the precursor. Compared with hard templates, soft templates formed by self-assembly of amphiphilic small molecules or block copolymers have stronger interaction forces with precursors, so the pore structure of hierarchical porous carbon materials can be more precisely regulated. However, the stability of soft templates is much lower than that of hard templates, and it is easy to cause structural collapse during the carbonization process. The direct carbonization method does not require any template, and the process is relatively simple, but it is difficult to precisely regulate the hierarchical porous carbon skeleton and pore structure.

[0004] The limitations of synthesis strategies have become the main obstacles restricting the large-scale production and further application of hierarchical porous carbon materials. The current key is to develop new synthesis strategies to achieve precise synthesis and regulation of hierarchical porous structures. Summary of the Invention

[0005] In order to solve the above technical problems existing in the prior art, this application provides a three-dimensional hierarchical porous carbon network material, a preparation method thereof, and an application thereof, so as to overcome the difficulties in the precise design and regulation of the pore structure of hierarchical porous carbon materials in the prior art.

[0006] In order to achieve the above object, the technical solution of the embodiment of this application is:

[0007] The first aspect of the present application provides a method for preparing a three-dimensional hierarchical porous carbon network material, and the preparation method includes:

[0008] Disperse a surfactant containing cetyltrimethylammonium cation CTA + and triethanolamine in water, add a tetraethyl orthosilicate / cyclohexane solution, carry out a stirring reaction, separate and purify, and then collect wrinkled mesoporous SiO2 nanospheres;

[0009] React the wrinkled mesoporous SiO2 nanospheres, a nitrogen-containing carbon source monomer, phytic acid, a non-ionic surfactant, and an initiator by dispersing them in water to obtain a mesoporous SiO2@polymer composite material;

[0010] After subjecting the composite material to high-temperature carbonization in an inert gas atmosphere, disperse it in an aqueous sodium hydroxide solution for etching, separate and purify, and then a three-dimensional hierarchical porous carbon network material is obtained.

[0011] Preferably in combination with the first aspect, the nitrogen-containing carbon source monomer is one or more of aniline, pyrrole, dopamine hydrochloride; and / or, the dispersion concentration of the wrinkled mesoporous SiO2 nanospheres is 10-20 g / L; and / or, the molar ratio of the nitrogen-containing carbon source monomer, the phytic acid, and the initiator is 1:1-3:1-3.

[0012] Preferably in combination with the first aspect, the surfactant containing CTA + is one or more of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride; and / or, the addition amount of the surfactant containing CTA + is 2-4 g; and / or, the addition amount of the triethanolamine is 0.5-1.0 mL, and the concentration is 0.35 g / mL.

[0013] Preferably in combination with the first aspect, the addition amount of the tetraethyl orthosilicate is 3-5 mL; and / or, the addition amount of the cyclohexane is 15-25 mL; and / or, the stirring reaction time is 12-20 h.

[0014] Preferably in combination with the first aspect, the non-ionic surfactant is one or more of poly(ethylene oxide)-poly(propylene oxide), poly(ethylene oxide)-poly(butylene oxide), poly(ethylene oxide)-polystyrene, poly(ethylene oxide)-poly(methyl methacrylate) diblock copolymer, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) triblock copolymer.

[0015] Preferably in combination with the first aspect, the initiator is one or more of ammonium persulfate, hydrogen peroxide, and iron chloride.

[0016] Preferably, in combination with the first aspect, the carbonization temperature is 700-1000 °C, the heating rate is 5-10 °C / min, and the carbonization time is 2-5 h; and / or, the inert gas is one or more of nitrogen and argon, and the gas flow rate is 20-60 mL / min.

[0017] Preferably, in combination with the first aspect, the concentration of the sodium hydroxide aqueous solution is 2-4 mol / L, and the reaction time is 5-8 h.

[0018] The second aspect of the present application provides a three-dimensional hierarchical porous carbon network material prepared by the method described in the first aspect. The three-dimensional hierarchical porous carbon network material has the characteristics of N, O, and P co-doping and a high specific surface area, and the formed microporous-mesoporous-macroporous multi-level pore structure can be precisely regulated.

[0019] The third aspect of the present application provides an application of the three-dimensional hierarchical porous carbon network material prepared by any of the methods described in the first aspect or the three-dimensional hierarchical porous carbon network material described in the second aspect in the negative electrode of a lithium-ion battery.

[0020] Compared with the prior art, the advantages or beneficial effects of the embodiments of the present application at least include:

[0021] For the method for preparing a three-dimensional hierarchical porous carbon network material provided by the embodiments of the present application, on the one hand, a surfactant containing cetyltrimethyl quaternary ammonium cations is used as a soft template, and a SiO2 nanosphere hard template with a wrinkled mesoporous structure is obtained by a biphasic synthesis method. Its particle size, pore size, and pore shape can be flexibly regulated, so that the macropore size distribution and shape in the three-dimensional hierarchical porous carbon network material can be precisely regulated; on the other hand, the non-ionic surfactant forms spherical micelles in water, which can act as a soft template to guide the polymerization process of the carbon source monomer and form mesopores during the high-temperature carbonization process; on the third hand, phytic acid acts like "glue" to stick the carbon source polymerization segments together, and atomic rearrangement occurs during the high-temperature carbonization process to form a large number of micropores. In this way, a three-dimensional hierarchical porous carbon network material with the characteristics of N, O, and P co-doping, a high specific surface area, and easy-to-regulate pore size is obtained by combining soft / hard templates.

[0022] The three-dimensional hierarchical porous carbon network material provided by the embodiments of the present application has a microporous-mesoporous-macroporous multi-level pore structure, with a micropore diameter of 1-2 nm, a mesopore diameter of 3-5 nm, a macropore diameter of 50-70 nm, and a specific surface area of 700-1000 m 2 / g, and has the characteristics of nitrogen, oxygen, and phosphorus co-doping.

[0023] When the three-dimensional hierarchical porous carbon network material provided by the embodiments of the present application is applied to the negative electrode of a lithium-ion battery, it exhibits excellent rate performance and cycle stability. Description of the Drawings

[0024] Figure 1 X-ray diffraction patterns of the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3;

[0025] Figure 2 Scanning electron microscope image of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1;

[0026] Figure 3 Transmission electron microscope image of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1;

[0027] Figure 4 Schematic diagram of the energy spectrum analysis results of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1;

[0028] Figure 5 Elemental surface distribution result map of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1;

[0029] Figure 6 Nitrogen adsorption-desorption isotherm curve and corresponding pore size distribution curve graph of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1;

[0030] Figure 7 Galvanostatic charge-discharge performance curves of the first, second, third, and fifth cycles of the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3;

[0031] Figure 8 Rate performance graphs of the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3;

[0032] Figure 9 Cycling performance graphs of the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3 at a current density of 0.5 A / g;

[0033] Figure 10 Cycling performance graph of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1 at a current density of 1.0 A / g. Detailed implementation manners

[0034] In order to make the objectives, technical solutions, and advantages of this application clearer, the following will further describe this application in detail in conjunction with the accompanying drawings. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

[0035] In the following description, reference is made to "some embodiments", which describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict. Unless otherwise defined, all technical and scientific terms used in the embodiments of the present application have the same meaning as commonly understood by those skilled in the technical field to which the embodiments of the present application belong. The terms used in the embodiments of the present application are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0036] In the following description of this embodiment, terms such as "comprising", "including", "having", and "containing" are all open-ended terms, meaning including but not limited to.

[0037] It should be noted that all raw materials / reagents in the embodiments of the present application can be purchased on the market or prepared by conventional methods well-known to those skilled in the art; the term "and / or" in the embodiments of the present application is only used to describe the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B represents three situations: A exists alone, B exists alone, and A and B exist simultaneously. Among them, A and B can be singular or plural, and the character " / " generally represents an "or" relationship between the associated objects before and after.

[0038] In the following description of this embodiment, the term "at least one" means one or more, and "a plurality" means two or more. "At least one of the following" or its similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0039] Those skilled in the art should understand that in the following description of the embodiments of the present application, the sequence numbers do not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0040] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0041] Those skilled in the art should understand that the numerical ranges in the embodiments of the present application should be understood as specifically disclosing each intermediate value between the upper and lower limits of the range. Each intermediate value between any stated value and the stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0042] Unless otherwise specified, the technical / scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application pertains. Although this application only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the embodiments or test examples of this application. All documents mentioned in this specification are generally incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this application shall prevail.

[0043] It should be noted that all raw materials and / or reagents in the embodiments of this application are purchased on the market or obtained by preparing according to the conventional methods well-known to those skilled in the art.

[0044] In a first aspect, the embodiments of this application provide a preparation method of a three-dimensional hierarchical porous carbon network material, and the preparation method includes:

[0045] Disperse a surfactant containing cetyltrimethylammonium cation CTA + and triethanolamine in water, add a tetraethyl orthosilicate / cyclohexane solution, carry out a stirring reaction, separate and purify, and then collect wrinkled mesoporous SiO2 nanospheres;

[0046] React the wrinkled mesoporous SiO2 nanospheres, a nitrogen-containing carbon source monomer, phytic acid, a non-ionic surfactant, and an initiator by dispersing them in water to obtain a mesoporous SiO2@polymer composite material;

[0047] Carry out high-temperature carbonization of the composite material in an inert gas atmosphere, disperse it in an aqueous sodium hydroxide solution for etching, separate and purify, and then obtain the three-dimensional hierarchical porous carbon network material.

[0048] In specific embodiments, the nitrogen-containing carbon source monomer in the embodiments of this application is preferably one of aniline, pyrrole, and dopamine hydrochloride.

[0049] In specific embodiments, the dispersion concentration of the wrinkled mesoporous SiO2 nanospheres in the embodiments of this application is preferably 10-20 g / L.

[0050] It should be noted that the wrinkled mesoporous SiO2 nanospheres act as a hard template agent in the synthesis process of the mesoporous SiO2@polymer composite material, and their addition amount directly affects the cross-linking polymerization process of the carbon source monomer and phytic acid and the pore structure of the three-dimensional hierarchical porous carbon network material. When the concentration of the dispersion liquid of the wrinkled mesoporous SiO2 nanospheres is less than 10 g / L, the number of reaction interfaces provided by the SiO2 nanospheres is too small, resulting in insufficient landing points for the micelles formed by the non-ionic surfactant, and the nitrogen-containing carbon source monomer and phytic acid directly undergo cross-linking polymerization reactions, thereby affecting the distribution of the hard template of SiO2 nanospheres and the soft template of micelles in the composite material, and ultimately significantly reducing the number of macropores and mesopores in the obtained carbon network material. When the concentration of the dispersion liquid of the wrinkled mesoporous SiO2 nanospheres is greater than 20 g / L, the SiO2 nanospheres are prone to agglomeration and sedimentation, and a uniformly dispersed hard template of nanospheres cannot be formed during the reaction process, resulting in non-uniform macropore sizes in the composite material formed after high-temperature carbonization and etching.

[0051] In specific embodiments, the molar ratio of the nitrogen-containing carbon source monomer, phytic acid, and initiator in the embodiments of the present application is preferably 1:1 to 3:1 to 3.

[0052] It should be noted that the nitrogen-containing carbon source monomer in the embodiments of the application serves as a carbon source and a nitrogen source, the initiator initiates the polymerization reaction of the nitrogen-containing carbon source monomer, and phytic acid serves as a cross-linking agent to "adhere" the polymerized chain segments of the carbon source to form a three-dimensional structure. The input amounts of these three need to be controlled within a suitable ratio range to obtain a three-dimensional network structure with adjustable pore structure. When the proportion of the initiator is too small, the polymerization rate of the carbon source monomer is too slow, the degree of polymerization of the polymer in the obtained composite material is relatively low, its heat resistance is poor, and the yield of the carbon product after high-temperature carbonization is very low; when the proportion of the initiator is too large, it will lead to too fast polymerization reaction rate, and it is difficult to control the polymerization process of the carbon source monomer on the surface of the micelles and the surface of the SiO2 nanospheres, resulting in non-uniform macropores and mesopores in the final carbon material. When the proportion of phytic acid is too small, the cross-linking degree of the polymerized chain segments of the carbon source is too low, and the strength and stiffness of the polymer in the obtained composite material are insufficient, and its heat resistance is poor; when the proportion of phytic acid is too large, not only can it not further increase the cross-linking degree of the polymerized chain segments of the carbon source, but its abundant P-OH will also cover a large area on the surface of the SiO2 nanospheres, resulting in insufficient landing points for the micelles formed by the non-ionic surfactant, affecting the polymerization process of the nitrogen-containing carbon source monomer on the surface of the SiO2 hard template, and ultimately significantly reducing the number of macropores in the obtained carbon material.

[0053] In specific embodiments, the surfactant containing quaternary ammonium cations in the embodiments of the present application is preferably one of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride.

[0054] It should be noted that these containing CTA +The surfactant belongs to a kind of cationic surfactant and serves as a soft template agent during the synthesis of SiO2, guiding the hydrolysis and condensation process of the organosilicon source, thereby forming uniform wrinkled mesoporous channels in the SiO2 nanospheres.

[0055] In specific embodiments, the surfactant containing CTA in the embodiments of the present application + The addition amount of the surfactant is preferably 2 - 4 g.

[0056] It should be noted that these quaternary ammonium cation surfactants serve as soft template agents in the SiO2 synthesis reaction, and their addition amount directly affects the mesoporous structure of SiO2, while the mesoporous structure of SiO2 directly affects the polymerization state of the carbon source precursor on the pore surface. When the addition amount is less than 2 g, these surfactants may not provide sufficient template or structure guiding effects, resulting in an incomplete structure of the generated SiO2 nanospheres, with an unclear or missing wrinkled structure; when the addition amount is greater than 4 g, it will change the shape of the mesoporous SiO2 nanosphere pores, and at the same time, the excessive surfactant may increase the difficulty of purification and is difficult to remove by simple separation methods.

[0057] In specific embodiments, the addition amount of triethanolamine in the embodiments of the present application is preferably 0.5 - 1.0 mL, and the concentration is preferably 0.35 g / mL.

[0058] It should be noted that triethanolamine in the embodiments of the present application serves as a catalyst in the SiO2 synthesis reaction, capable of regulating the hydrolysis of tetraethyl orthosilicate and the nucleation rate of nanoparticles, thereby regulating the particle size and uniformity of SiO2. Therefore, the addition amount of triethanolamine is jointly determined by the solution volume and concentration.

[0059] Among them, when the addition amount of triethanolamine is too small, the reaction rate is too slow, and the generated SiO2 particle size is too small; when the addition amount of triethanolamine is too large, it is not conducive to regulating the reaction rate, resulting in the rapid growth of SiO2 nanoparticles, and finally the particle size is too large and the uniformity is poor.

[0060] In specific embodiments, the addition amount of tetraethyl orthosilicate in the embodiments of the present application is preferably 3 - 5 mL.

[0061] It should be noted that tetraethyl orthosilicate is the main silicon source. When the addition amount of tetraethyl orthosilicate is less than 3 mL, due to insufficient silicon source, the number of generated SiO2 nanospheres may decrease, resulting in a reduced yield. Secondly, a complete wrinkled mesoporous structure cannot be formed; when the addition amount of tetraethyl orthosilicate is greater than 5 mL, because the collision opportunities between silicon source molecules increase, more nucleation and growth points are generated, and the formed SiO2 nanospheres have too small a particle size.

[0062] In specific embodiments, the addition amount of cyclohexane in the embodiments of the present application is preferably 15 - 25 mL.

[0063] It should be noted that when cyclohexane is used as a solvent or dispersant for tetraethyl orthosilicate, if the addition amount of cyclohexane is too high, the concentration of tetraethyl orthosilicate is too low; if the addition amount of cyclohexane is too low, the concentration of tetraethyl orthosilicate is too high. The concentration of tetraethyl orthosilicate directly affects the particle size and mesoporous structure of the target SiO2.

[0064] In a specific embodiment, the stirring reaction time of the embodiment of the present application is preferably 12 to 20 h.

[0065] In a specific embodiment, the non-ionic surfactant of the embodiment of the present application is preferably one of poly(ethylene oxide)-poly(propylene oxide), poly(ethylene oxide)-poly(butylene oxide), poly(ethylene oxide)-polystyrene, poly(ethylene oxide)-poly(methyl methacrylate) diblock copolymer, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, and poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) triblock copolymer.

[0066] In a specific embodiment, the initiator of the embodiment of the present application is preferably one of ammonium persulfate, hydrogen peroxide, and iron chloride.

[0067] In a specific embodiment, the carbonization temperature of the embodiment of the present application is preferably 700 to 1000 °C, the heating rate is preferably 5 to 10 °C / min, and the carbonization time is preferably 2 to 5 h.

[0068] In a specific embodiment, the inert gas of the embodiment of the present application is preferably one of nitrogen and argon; the gas flow rate is preferably 20 to 60 mL / min.

[0069] In a specific embodiment, the concentration of the sodium hydroxide aqueous solution of the embodiment of the present application is preferably 2 to 4 mol / L, and the reaction time is preferably 5 to 8 h.

[0070] It should be noted that when the concentration of the sodium hydroxide aqueous solution is less than 2 mol / L, the reaction rate with SiO2 will slow down, resulting in a longer time required for the etching process to be completed. Otherwise, the SiO2 template cannot be completely removed, resulting in an incomplete pore structure in the carbon material, and the pores may be blocked or not fully opened. When the concentration of the sodium hydroxide aqueous solution is greater than 4 mol / L, the too fast etching rate may cause damage to the structure of the carbon material itself, such as thinning of the pore wall and collapse of the pores, thus affecting its mechanical stability and chemical stability.

[0071] In a second aspect, the embodiment of the present application provides a three-dimensional hierarchical porous carbon network material prepared by the method described in the first aspect.

[0072] The three-dimensional hierarchical porous carbon network material provided by the embodiment of the present application has a multi-level pore structure of micropores-mesopores-macropores. The micropore diameter is 1-2 nm, the mesopore diameter is 3-5 nm, the macropore diameter is 50-70 nm, and the specific surface area is 700-1000 m 2 / g, and has the characteristics of nitrogen, oxygen, and phosphorus co-doping.

[0073] In a third aspect, the embodiment of the present application provides an application of the three-dimensional hierarchical porous carbon network material prepared by any of the methods in the first aspect or the three-dimensional hierarchical porous carbon network material in the second aspect in the negative electrode of a lithium-ion battery.

[0074] When the three-dimensional hierarchical porous carbon network material provided by the embodiment of the present application is applied to the negative electrode of a lithium-ion battery, it exhibits excellent rate performance and cycle stability.

[0075] The technical method of the present application will be further elaborated below with specific embodiments.

[0076] Example 1

[0077] This Example 1 provides a preparation method of a three-dimensional hierarchical porous carbon network material 1 and a lithium-ion battery 1. The specific steps are as follows:

[0078] (1) Preparation of the three-dimensional hierarchical porous carbon network material 1:

[0079] Mix 3 g of cetyltrimethylammonium bromide (CTAB) and 0.75 mL of triethanolamine (TEA) aqueous solution in 60 mL of deionized water. Heat the mixed solution to 60 °C, stir for 0.5 h, then add tetraethyl orthosilicate (TEOS) / cyclohexane solution and continue stirring for 12 h. Add absolute ethanol for centrifugal separation, and dry to obtain wrinkled mesoporous SiO2 nanospheres;

[0080] Dissolve 0.6 g of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (Pluronic F127) in 10 mL of deionized water and stir at room temperature for 5 h to obtain a Pluronic F127 solution; Dissolve 0.5 g of the above-obtained wrinkled mesoporous SiO2 nanospheres in 40 mL of deionized water and ultrasonically disperse them evenly. Place the evenly dispersed mixed solution under certain conditions, add 0.4 mL of aniline and 1.35 mL of phytic acid and stir for 0.5 h, then add the mixed Pluronic F127 solution and continue stirring for 6 h. Add absolute ethanol and deionized water for centrifugal separation respectively. Place the obtained product in an oven to dry to obtain mesoporous SiO2@polyaniline-phytic acid composite materials;

[0081] The obtained mesoporous SiO2@polyaniline-phytic acid composite material was placed in a corundum boat, and the corundum boat was placed in a tube furnace. After continuously introducing an inert gas, the tube furnace was heated to 350 °C at a heating rate of 1 °C / min and reacted for 2 h, then heated to 900 °C at a heating rate of 10 °C / min, and after reacting for 2 h, it was cooled to room temperature to obtain a mesoporous SiO2@carbon composite material. Subsequently, it was placed in a sodium hydroxide solution with a concentration of 3.0 mol / L and stirred for 6 h. After centrifugation and drying, a three-dimensional hierarchical porous carbon network material 1 was obtained.

[0082] (2) Preparation of lithium-ion battery 1:

[0083] The three-dimensional hierarchical porous carbon network material 1, polyvinylidene fluoride (PVDF), and conductive carbon black (Super P) obtained in Example 1 above were thoroughly ground according to a mass ratio of 8:1:1. After adding N-methylpyrrolidone (NMP) and continuing to grind and mix evenly, a black paste-like slurry was obtained. The black slurry was evenly coated on a copper foil, and after drying, it was cut into an electrode sheet with a diameter of 10 mm as the negative electrode of the lithium-ion battery. A lithium sheet was used as the reference electrode, a polypropylene (PP) film was used as the separator, and a mixed solution with 1 M lithium hexafluorophosphate (LiPF6) as the solute and ethylene carbonate (EC):ethyl methyl carbonate (EMC) with a volume ratio of 3:7 as the solvent was used as the electrolyte. A CR2032 type button battery was assembled in a glove box, and its electrochemical performance was tested after standing for 8 h.

[0084] Example 2

[0085] This Example 2 provides a preparation method of a three-dimensional hierarchical porous carbon network material 2, and the specific steps are as follows:

[0086] (1) Preparation of three-dimensional hierarchical porous carbon network material 2:

[0087] 3 g of CTAB and 0.75 mL of TEA aqueous solution were mixed in 60 mL of deionized water. The mixed solution was heated to 60 °C, and after stirring for 0.5 h, TEOS / cyclohexane solution was added and stirred for another 12 h. Ethanol was added for centrifugal separation, and after drying, wrinkled mesoporous SiO2 nanospheres were obtained;

[0088] 0.3 g of the obtained wrinkled mesoporous SiO2 nanospheres were mixed in 40 mL of deionized water and ultrasonically dispersed evenly. The evenly dispersed mixed solution was placed under an ice bath condition, 0.4 mL of aniline and 1.35 mL of phytic acid were added and stirred for 0.5 h, then 1.0 g of ammonium persulfate was dissolved in 10 mL of deionized water and added and stirred for 6 h. Ethanol and deionized water were added for centrifugal separation respectively, and the obtained product was placed in a drying oven for drying to obtain a mesoporous SiO2@polyaniline-phytic acid composite material;

[0089] The obtained mesoporous SiO2@polyaniline-phytic acid composite material was placed in a corundum boat, and the corundum boat was placed in a tube furnace. After continuously introducing an inert gas, the tube furnace was first heated to 350 °C at a heating rate of 1 °C / min, reacted for 2 h, then heated to 900 °C at a heating rate of 10 °C / min, and after reacting for 2 h, it was cooled to room temperature to obtain a mesoporous SiO2@carbon composite material, which was then placed in a sodium hydroxide solution with a concentration of 3.0 mol / L and stirred for 6 h. After centrifugation and drying, a three-dimensional hierarchical porous carbon network material 2 was obtained.

[0090] (2) Preparation of lithium-ion battery 2:

[0091] The three-dimensional hierarchical porous carbon network material 2, PVDF, and Super P obtained in Example 2 above were thoroughly ground in a mass ratio of 8:1:1. After adding NMP and continuing to grind and mix evenly, a black paste-like slurry was obtained. The black slurry was evenly coated on a copper foil, and after drying, it was cut into an electrode sheet with a diameter of 10 mm as the negative electrode of the lithium-ion battery. A lithium sheet was used as the counter electrode, a PP film was used as the separator, and a mixed solution with 1 M LiPF6 as the solute and a volume ratio of 3:7 of EC:EMC as the solvent was used as the electrolyte. A CR2032 type button battery was assembled in a glove box, and its electrochemical performance was tested after standing for 8 h.

[0092] Example 3

[0093] Example 3 provides a preparation method for a three-dimensional hierarchical porous carbon network material 3 and a lithium-ion battery 3, and the specific steps are as follows:

[0094] (1) Preparation of three-dimensional hierarchical porous carbon network material 3:

[0095] 3 g of CTAB and 0.75 mL of TEA aqueous solution were mixed in 60 mL of deionized water. The mixed solution was heated to 60 °C and stirred for 0.5 h. Then, a TEOS / cyclohexane solution was added and stirring continued for 12 h. Anhydrous ethanol was added for centrifugal separation, and after drying, wrinkled mesoporous SiO2 nanospheres were obtained.

[0096] Dissolve 0.6 g of Pluronic F127 in 10 mL of deionized water and stir at room temperature for 5 h to obtain a Pluronic F127 solution; mix 0.5 g of the obtained wrinkled mesoporous SiO₂ nanospheres with 40 mL of deionized water and disperse them evenly by ultrasonic treatment. Place the evenly dispersed mixed solution under ice bath conditions, add 0.8 mL of aniline and 2.7 mL of phytic acid and stir for 0.5 h. Then dissolve 2.0 g of ammonium persulfate in 10 mL of deionized water, pre-cool it and add it and stir for 0.5 h. Then add the Pluronic F127 solution that has been stirred for 5 h and continue to stir for 6 h. Add anhydrous ethanol and deionized water respectively for centrifugal separation, and place the obtained product in a drying oven for drying to obtain a mesoporous SiO₂@polyaniline-phytic acid composite material;

[0097] Place the obtained mesoporous SiO₂@polyaniline-phytic acid composite material in a corundum boat, place the corundum boat in a tube furnace. After continuously introducing an inert gas, first heat the tube furnace to 350 °C at a heating rate of 1 °C / min and react for 2 h, then heat it to 900 °C at a heating rate of 10 °C / min and react for 2 h, and then cool it to room temperature to obtain a mesoporous SiO₂@carbon composite material. Subsequently, place it in a sodium hydroxide solution with a concentration of 3.0 mol / L and stir for 6 h. After centrifugal drying, obtain a three-dimensional hierarchical porous carbon network material 3.

[0098] (2) Preparation of lithium-ion battery 3:

[0099] Fully grind the three-dimensional hierarchical porous carbon network material 3, PVDF and Super P obtained in Example 3 above according to a mass ratio of 8:1:1, add NMP and continue to grind and mix evenly to obtain a black paste-like slurry. Coat the black slurry evenly on a copper foil, and after drying, cut it into an electrode sheet with a diameter of 10 mm as the negative electrode of the lithium-ion battery. Use a lithium sheet as the reference electrode, a PP film as the separator, and a mixed solution with 1 M LiPF₆ as the solute and a volume ratio of 3:7 of EC:EMC as the solvent as the electrolyte, and assemble a CR2032 type button battery in a glove box. After standing for 8 h, test its electrochemical performance.

[0100] In order to verify the relevant properties of the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3 above, perform performance tests on the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3. The test results are as Figures 1 to 10 shown. Figure 1 is the X-ray diffraction pattern of the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3. Figure 2 is the scanning electron microscope image of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1. Figure 3 is the transmission electron microscope image of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1. Figure 4Schematic diagram of the energy spectrum analysis results of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1. Figure 5 Elemental surface distribution result diagram of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1.

[0101] Figure 6 Nitrogen adsorption-desorption isotherm curve and corresponding pore size distribution curve of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1. Figure 7 Galvanostatic charge-discharge performance curves of the first, second, third, and fifth cycles of the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3. Figure 8 Rate performance diagram of the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3. Figure 9 Cycling performance diagram of the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3 at a current density of 0.5 A / g. Figure 10 Cycling performance diagram of the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1 at a current density of 1.0 A / g.

[0102] According to Figure 1 It can be seen that the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3 have strong characteristic diffraction peaks of graphite (002) and (101) crystal planes, indicating that their structures have undergone local graphitization. Among them, the positions of the characteristic diffraction peaks of the (002) crystal plane of the three-dimensional hierarchical porous carbon network materials 1-3 prepared in Examples 1-3 are 23.5°, 23.3°, and 23.5°. Compared with the characteristic diffraction peak of the graphite (002) crystal plane, they are all biased towards lower angles. According to the Bragg equation 2dsinθ = nλ, the layer spacings of the three materials are expanded from 0.338 nm to 0.386 nm, 0.390 nm, and 0.386 nm respectively.

[0103] According to Figure 2 It can be seen that the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1 has a network-like morphology, which is supported by the interconnected macropores formed after the etching of a large number of mesoporous SiO2 hard templates and the mesopores constructed by the Pluronic F127 soft template.

[0104] According to Figure 3 It can be seen that the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1 has macropores with pore sizes of 50-100 nm and mesopores with pore sizes of about 20 nm.

[0105] According to Figure 4 It can be seen that the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1 is doped with N, P, and O elements.

[0106] According to Figure 5 It can be seen that the N, P, and O elements in the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1 are uniformly doped in the carbon skeleton.

[0107] According to Figure 6 it can be seen that the nitrogen adsorption - desorption isotherm curve of the three - dimensional hierarchical porous carbon network material 1 prepared in Example 1 is a typical Type Ⅳ isotherm curve, indicating that there are a large number of mesopores in the material, and the adsorption characteristics in the low - pressure section also indicate the existence of a large number of micropores. The measured specific surface area is 791 m 2 / g. From the corresponding pore size distribution curve, it can be known that the most probable pore sizes are 0.8, 1.3, 3.6 and 22 nm, fully indicating the co - existence of micropores and mesopores in the material.

[0108] According to Figure 7 it can be seen that the initial discharge specific capacities of the three - dimensional hierarchical porous carbon network materials 1 - 3 prepared in Examples 1 - 3 at a current density of 0.1 A / g are as high as 1824.3, 1406.3, 1616.0 mAh / g respectively. During the subsequent cycling process, the curves coincide well, indicating good battery cycling performance.

[0109] According to Figure 8 it can be seen that the specific capacities of the three - dimensional hierarchical porous carbon network material 1 prepared in Example 1 at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, 5.0 A / g are 756.2, 555.4, 397.9, 320.6, 264.6, 167.7 mAh / g respectively, indicating that the material has excellent rate performance; the specific capacities of the three - dimensional hierarchical porous carbon network material 2 prepared in Example 2 at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, 5.0 A / g are 631.2, 490.6, 367.2, 299.0, 243.8, 168.2 mAh / g respectively, indicating that the material has excellent rate performance; the specific capacities of the three - dimensional hierarchical porous carbon network material 3 prepared in Example 3 at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, 5.0 A / g are 562.4, 416.0, 304.0, 241.4, 191.6, 120.7 mAh / g respectively, indicating that the material has excellent rate performance.

[0110] According to Figure 9 it can be seen that the capacity retention rate of the three - dimensional hierarchical porous carbon network material 1 prepared in Example 1 after 600 stable cycles at a current density of 0.5 A / g can reach 101.6%; the capacity retention rate of the three - dimensional hierarchical porous carbon network material 2 prepared in Example 2 after 600 stable cycles at a current density of 0.5 A / g can reach 66.1%; the capacity retention rate of the three - dimensional hierarchical porous carbon network material 3 prepared in Example 3 after 600 stable cycles at a current density of 0.5 A / g can reach 81.5%.

[0111] According to Figure 10It can be seen that the three-dimensional hierarchical porous carbon network material 1 prepared in Example 1 remains very stable after 2000 cycles at a current density of 1.0 A / g, and the specific capacity is 222.5 mAh / g.

[0112] As described above, only the specific embodiments of the present application are provided, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of changes or substitutions, which should all be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for preparing a three-dimensional hierarchical porous carbon network material, characterized in that: include: CTA containing hexadecyltrimethyl quaternary ammonium cation + The surfactant and triethanolamine are dispersed in water, tetraethyl orthosilicate / cyclohexane solution is added, stirred for reaction, separated and purified, and then wrinkled mesoporous SiO2 nanospheres are collected; The wrinkled mesoporous SiO2 nanospheres, nitrogen-containing carbon source monomers, phytic acid, nonionic surfactants and initiators are dispersed in water for reaction to obtain a mesoporous SiO2@polymer composite material; The composite material is subjected to high-temperature carbonization in an inert gas atmosphere, dispersed in a sodium hydroxide aqueous solution for etching, separation and purification, and thus a three-dimensional hierarchical porous carbon network material is obtained; The dispersion concentration of the wrinkled mesoporous SiO2 nanospheres is 10-20 g / L; the molar ratio of the nitrogen-containing carbon source monomer, the phytic acid and the initiator is 1:1-3:1-3.

2. The method for preparing a three-dimensional hierarchical porous carbon network material according to claim 1, characterized in that: The nitrogen-containing carbon source monomer is one or more of aniline, pyrrole and dopamine hydrochloride.

3. The method for preparing a three-dimensional hierarchical porous carbon network material according to claim 1, characterized in that: The CTA + The surfactant is one or more of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride; And / or, the CTA + The amount of surfactant added is 2~4 g; And / or, the amount of triethanolamine added is 0.5-1.0 mL, and the concentration is 0.35 g / mL.

4. The method for preparing a three-dimensional hierarchical porous carbon network material according to claim 1, characterized in that: The amount of tetraethyl orthosilicate added is 3-5 mL; And / or, the amount of cyclohexane added is 15-25 mL; And / or, the stirring reaction time is 12 to 20 h.

5. The method for preparing the three-dimensional hierarchical porous carbon network material according to claim 1, characterized in that: The nonionic surfactant is one or more of polyethylene oxide-polypropylene oxide, polyethylene oxide-polybutylene oxide, polyethylene oxide-polystyrene, polyethylene oxide-polymethyl methacrylate diblock copolymer, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and polypropylene oxide-polyethylene oxide-polypropylene oxide triblock copolymer.

6. The method for preparing a three-dimensional hierarchical porous carbon network material according to claim 1, characterized in that: The initiator is one or more of ammonium persulfate, hydrogen peroxide and ferric chloride.

7. The method for preparing a three-dimensional hierarchical porous carbon network material according to claim 1, characterized in that: The carbonization temperature is 700-1000°C, the heating rate is 5-10°C / min, and the carbonization time is 2-5 h; And / or, the inert gas is one or more of nitrogen and argon, and the gas introduction flow rate is 20-60 mL / min.

8. The method for preparing a three-dimensional hierarchical porous carbon network material according to claim 1, characterized in that: The concentration of the sodium hydroxide aqueous solution is 2-4 mol / L, and the reaction time is 5-8 h.

9. A three-dimensional hierarchical porous carbon network material prepared according to any one of claims 1 to 8, characterized in that: The three-dimensional hierarchical porous carbon network material has N, O and P triple doping characteristics and a high specific surface area, and the formed micropore-mesopore-macroporous multi-layer pore structure can be precisely controlled.

10. Use of a three-dimensional hierarchical porous carbon network material prepared by the method of any one of claims 1 to 8 or a three-dimensional hierarchical porous carbon network material according to claim 9 in a negative electrode of a lithium ion battery.

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