Macroporous carbon sphere, preparation method thereof and rechargeable near-neutral zinc air battery comprising macroporous carbon sphere

Abstract

The invention relates to the technical field of mesoporous material preparation, and discloses a macroporous carbon sphere as well as a preparation method and application thereof. The macroporous carbon sphere provided by the invention has a pore channel structure diverging in the center; the pore diameter is 7-150nm, the specific surface area is 80-1600m < 2 > / g, and the pore volume is 0.2-1.5 cm < 3 > / g. The preparation method comprises the following steps: dissolving a first surfactant in a composite solvent to obtain a precursor solution; adding a pore-enlarging agent and a second surfactant into the precursor solution to obtain an emulsion; then adding a phenolic precursor, formaldehyde and a catalyst for reaction; collecting a solid phase, and carrying out heat treatment in an inert atmosphere to obtain macroporous phenolic resin spheres; and carrying out carbonization treatment in an inert atmosphere to obtain the macroporous carbon spheres. The macroporous carbon sphere has a large pore diameter and a highly open pore channel structure, uniform deposition of inert discharge products in pore channels can be realized, efficient ion transmission and gas diffusion are ensured, an excellent conductive network is maintained, and highly reversible generation and decomposition of the discharge products are realized.

Description

Technical Field

[0001] The present application relates to the technical field of mesoporous material preparation, and specifically relates to a macroporous carbon sphere, a preparation method thereof, and a rechargeable near-neutral zinc-air battery containing the same. Background Art

[0002] Traditional alkaline zinc-air batteries have high theoretical energy density and safety. However, the corrosion of the zinc negative electrode, dendrites caused by the alkaline electrolyte therein, and the accumulation of carbonates at the positive electrode have greatly reduced the reversibility of the battery. In recent years, researchers have focused on rechargeable near-neutral zinc-air batteries, such as the formation of zinc peroxide (ZnO2) under near-neutral conditions, and new zinc-air battery systems involving two-electron redox reactions (Science 2021, 371, 46-51), etc. This provides a new reaction pathway and alternative solution for highly reversible and sustainable zinc-air batteries. Compared with the traditional system, it has fewer side reactions and can operate stably in air.

[0003] However, due to the slow reaction kinetics of the air positive electrode in a near-neutral electrolyte, the battery will generate large polarization, resulting in low energy efficiency. In addition, the insoluble and insulating properties of ZnO2 tend to block the ion and electron transport pathways and hinder the active sites, exacerbating the deterioration of the reaction kinetics. Therefore, overcoming this obstacle in a near-neutral electrolyte is crucial for ensuring the effective operation of the near-neutral zinc-air battery and unleashing its full potential as a sustainable energy storage.

[0004] Currently, a variety of methods have been reported to improve the reaction kinetics of the air positive electrode, such as by designing a Mo 4 / 3 B 2-x T z MBene (Energy Environ. Sci. 2023, 16, 3407-3415), or a FeN2S2 single-atom catalyst confined in a mesoporous graphene framework (Nat. Sustain. 2024, 7, 463-473), both of which can effectively optimize the reaction kinetics of the air positive electrode and improve the energy efficiency of the battery. However, the energy efficiency of the current rechargeable near-neutral zinc-air battery is still limited to 60%, and there is still much room for improvement. Summary of the Invention

[0005] The present application provides a macroporous carbon sphere, a preparation method thereof, an electrode material containing the same, and a rechargeable near-neutral zinc-air battery, aiming to solve the technical problem of the low energy efficiency of the existing rechargeable near-neutral zinc-air battery.

[0006] To achieve the above object, the present application adopts the following technical solutions.

[0007] In the first aspect of the present application, a macroporous carbon sphere is provided, which has a pore structure diverging from the center;

[0008] Its pore diameter is 7 - 150 nm, the specific surface area is 80 - 1600 m 2 / g, and the pore volume is 0.2 - 1.5 cm 3 / g.

[0009] In the second aspect of the present application, a preparation method of the above macroporous carbon sphere is provided, including:

[0010] Dissolve the first surfactant in a composite solvent and stir evenly to obtain a precursor solution;

[0011] Add a pore-expanding agent and a second surfactant to the precursor solution to obtain a uniform emulsion;

[0012] Add a phenolic precursor and formaldehyde to the emulsion and stir evenly; then add a catalyst to carry out a polymerization reaction; after the reaction, collect the solid phase and perform heat treatment in an inert atmosphere to obtain a macroporous phenolic resin sphere;

[0013] Carry out carbonization treatment on the macroporous phenolic resin sphere in an inert atmosphere to obtain a macroporous carbon sphere.

[0014] Preferably, both the first surfactant and the second surfactant are polyether nonionic surfactants;

[0015] The second surfactant has a shorter hydrophilic block length than the first surfactant.

[0016] More preferably, the first surfactant includes at least one of F127, F108 or P105;

[0017] The second surfactant is at least one of P123 or L121.

[0018] Preferably, the composite solvent is a mixture of ethanol and water, wherein the volume fraction of ethanol is 20 - 80%;

[0019] And / or,

[0020] The phenolic precursor includes at least one of phenol, resorcinol, m-aminophenol, o-aminophenol or p-aminophenol;

[0021] And / or,

[0022] The pore-expanding agent is benzene and its derivatives, saturated aliphatic hydrocarbons or olefinic compounds;

[0023] And / or,

[0024] The catalyst is at least one of ammonia water, fatty amines, alkanolamines, aromatic amines, amides, aromatic amines or cycloaliphatic amines.

[0025] Preferably, based on the composite solvent, the concentration of the first surfactant is 0.05-5 wt%, the concentration of the phenolic precursor is 0.01-1 M, and the concentration of the catalyst is 0.1-1.5 M;

[0026] and / or,

[0027] The molar ratio of the formaldehyde to the phenolic precursor is (0.5-4):1;

[0028] The mass ratio of the second surfactant to the first surfactant is (0.1-5):1;

[0029] The mass ratio of the first surfactant to the pore former is (0.05-0.5):1.

[0030] Preferably, the temperature of the polymerization reaction is 15-80 °C;

[0031] and / or,

[0032] The temperature of the heat treatment is 300-500 °C;

[0033] and / or,

[0034] The temperature of the carbonization treatment is 700-1600 °C, and the time is 0.5-5 h;

[0035] and / or,

[0036] The inert atmosphere is helium, neon, argon, nitrogen or carbon dioxide atmosphere.

[0037] In the third aspect of the present application, there is provided an application of the above-mentioned macroporous carbon spheres or the macroporous carbon spheres prepared by the above-mentioned preparation method in a rechargeable near-neutral zinc-air battery.

[0038] In the fourth aspect of the present application, there is provided an electrode material, which comprises the above-mentioned macroporous carbon spheres or the macroporous carbon spheres prepared by the above-mentioned preparation method.

[0039] In the fifth aspect of the present application, there is provided a rechargeable near-neutral zinc-air battery, comprising a positive electrode, a negative electrode, an electrolyte and a separator;

[0040] The positive electrode comprises the above-mentioned electrode material;

[0041] The negative electrode is a zinc material;

[0042] The electrolyte is an aqueous solution of zinc trifluoromethanesulfonate, zinc bis(trifluoromethylsulfonyl)imide, zinc acetate or zinc sulfate;

[0043] The separator comprises at least one of a glass fiber separator, a polyethylene or a polypropylene microporous membrane.

[0044] Compared with the prior art, the beneficial effects of the present application are as follows:

[0045] The macroporous carbon spheres of the present application have a uniform spherical structure and a pore structure diverging from the center; their pore diameter is 7 - 150 nm, the specific surface area is 80 - 1600 m 2 / g, and the pore volume is 0.2 - 1.5 cm 3 / g; the solid content of the macroporous carbon spheres reaches 22 g / L -1 . Its preparation method has a simple process, low raw material prices, a high solid content, and the potential for large-scale production.

[0046] The macroporous carbon spheres of the present application have a relatively large pore diameter and a highly open pore structure. When used as the positive electrode material to assemble a rechargeable near-neutral zinc-air battery, it can achieve uniform deposition of inert discharge products inside the pores, ensure efficient ion transport and gas diffusion, maintain an excellent conductive network, and thus achieve highly reversible generation and decomposition of discharge products. The rechargeable near-neutral zinc-air battery containing the macroporous carbon spheres of the present application has a high energy efficiency (78.7%) and a long cycle life (650 h). BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0048] Figure 1 SEM image of the macroporous phenolic resin spheres prepared in Example 1;

[0049] Figure 2 High-magnification SEM image of the macroporous carbon spheres prepared in Example 1;

[0050] Figure 3 Large-range SEM image of the macroporous carbon spheres prepared in Example 1;

[0051] Figure 4 High-magnification transmission electron microscopy image of the macroporous carbon spheres prepared in Example 1;

[0052] Figure 5 High-magnification transmission electron microscopy image of the macroporous carbon spheres prepared in Example 1 after ultra-thin section treatment;

[0053] Figure 6 Nitrogen adsorption and desorption curve of the macroporous carbon spheres prepared in Example 1;

[0054] Figure 7 Pore size distribution diagram of the macroporous carbon spheres prepared in Example 1;

[0055] Figure 8 SEM images, transmission electron microscope images and pore size distribution diagrams of the carbon spheres prepared in Examples 1-4 and Comparative Example 1;

[0056] Figure 9 SEM images and transmission electron microscope images of the macroporous carbon spheres prepared in Example 4;

[0057] Figure 10 Rate performance diagram of the near-neutral zinc-air battery assembled with the macroporous carbon spheres prepared in Example 1;

[0058] Figure 11 Cycling performance diagram of the near-neutral zinc-air battery assembled with the macroporous carbon spheres prepared in Example 1. Detailed implementation manners

[0059] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0060] In the following description of this embodiment, the terms "including", "comprising", "having" and "containing" are all open-ended terms, that is, they are intended to include but not limited to.

[0061] In the following description of this embodiment, the term "and / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, B exists alone, and both A and B exist simultaneously. Wherein A and B may be singular or plural. The character " / " generally represents that the associated objects before and after are an "or" relationship.

[0062] 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 items (pieces)" or its similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces). 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 (that is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple respectively.

[0063] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only 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.

[0064] Those skilled in the art should understand that in the following description of the embodiments of the present application, the sequence numbers do not imply the order of execution, and some or all of the steps can be executed in parallel or sequentially. 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.

[0065] 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 within any stated value or 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 can be independently included or excluded from the range.

[0066] 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 the present application pertains. Although the present application only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present application. All documents mentioned in this specification are 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 specification shall prevail.

[0067] In a first aspect, the present application provides a macroporous carbon sphere having a pore structure diverging from the center; its pore diameter is 7 - 150 nm, the specific surface area is 80 - 1600 m 2 / g, and the pore volume is 0.2 - 1.5 cm 3 / g.

[0068] In the present application, in an ethanol / water mixed solution, a composite micelle formed by a surfactant F127 and a pore-expanding agent is used as a pore-forming agent; on this basis, a non-ionic surfactant (L121) with different hydrophilic block lengths is added for compounding, and by changing the micelle curvature, dynamic regulation of the micelle from small to large is achieved; the micelles are assembled with the precursor through hydrogen bond interaction, and then the surfactant can be removed by low-temperature heat treatment to obtain a macroporous phenolic resin sphere with a divergent pore structure, and then a macroporous carbon sphere can be obtained through further high-temperature carbonization. Specifically, the preparation method of the macroporous carbon sphere of the present application includes:

[0069] Dissolve the first surfactant in a composite solvent and stir evenly to obtain a precursor solution;

[0070] A pore-expanding agent and a second surfactant are added to the precursor solution to obtain a uniform emulsion.

[0071] A phenolic precursor and formaldehyde are added to the emulsion, stirred evenly, and then a catalyst is added for a polymerization reaction; after the reaction, the solid phase is collected and heat-treated under an inert atmosphere to obtain macroporous phenolic resin spheres.

[0072] The macroporous phenolic resin spheres are carbonized under an inert atmosphere to obtain macroporous carbon spheres.

[0073] In this application, the composite solvent is a mixture of ethanol and water, wherein the volume fraction of ethanol is 20 - 80%.

[0074] In this application, both the first surfactant and the second surfactant are triblock polyether nonionic surfactants; among them, the second surfactant has a shorter hydrophilic block length than the first surfactant.

[0075] Specifically, the first surfactant is at least one of F127, F108, or P105, preferably F127; its concentration in the composite solvent is preferably 0.05 - 5 wt%. The second surfactant is at least one of P123 or L121, preferably L121, and the mass ratio of the second surfactant to the first surfactant is (0.1 - 5):1.

[0076] Among them, the chemical structural formula of F127 is as follows:

[0077]

[0078] The chemical structural formula of L121 is as follows:

[0079]

[0080] In this application, the above-mentioned surfactants F127, F108, P105, P123, and L121 are all purchased from Sigma - Aldrich.

[0081] In this application, the phenolic precursor includes at least one of phenol, resorcinol, m - aminophenol, o - aminophenol, or p - aminophenol, and its molar concentration in the composite solvent is 0.01 - 1 M. The molar ratio of formaldehyde to the phenolic precursor is preferably (0.5 - 4):1.

[0082] In this application, the pore former can be an oil-phase substance, such as benzene and its derivatives, saturated aliphatic hydrocarbons or olefin compounds. Specifically, the pore former can be at least one of toluene, xylene, mesitylene, cyclohexane, n-hexane, decalin or octadecene. The composite micelle formed by the pore former and the triblock surfactant is used as a pore-forming agent, and the mass ratio of the first surfactant to the pore former is (0.05 - 0.5):1.

[0083] In this application, the catalyst includes at least one of ammonia water, fatty amine, alkanolamine, aromatic amine, amide, aromatic amine or alicyclic amine; its molar concentration in the composite solvent is 0.1 - 1.5 M.

[0084] In this application, the temperature of the polymerization reaction is 15 - 80 °C, and the reaction time is preferably 1 - 72 h. The solid phase obtained after the polymerization reaction is a composite of surfactant and phenolic resin spheres. By heat-treating the composite in an inert atmosphere, the surfactant and the pore former are removed to obtain macroporous phenolic resin spheres. Among them, the inert atmosphere is helium, neon, argon, nitrogen or carbon dioxide atmosphere; the temperature of the heat treatment is 300 - 500 °C, and the heat treatment time is 2 - 4 h, preferably 3 h.

[0085] In this application, the macroporous phenolic resin spheres are heated in an inert atmosphere at a heating rate of 0.1 - 20 °C / min to 700 - 1600 °C and kept at a constant temperature for 0.5 - 5 h for carbonization treatment to obtain macroporous carbon spheres. Among them, the inert atmosphere is helium, neon, argon, nitrogen or carbon dioxide atmosphere.

[0086] The preparation method of this application has a simple process, low raw material price, high solid content, and the potential for large-scale production.

[0087] The macroporous carbon spheres of this application have larger pore diameters and highly open pore structures, and can be used as the positive electrode material for rechargeable near-neutral zinc-air batteries. It can achieve uniform deposition of inert discharge products inside the pores, ensure efficient ion transport and gas diffusion, maintain an excellent conductive network, thereby realizing highly reversible generation and decomposition of discharge products, and improving the energy efficiency and cycle life of rechargeable near-neutral zinc-air batteries.

[0088] This application also provides an electrode material, which includes the above-mentioned macroporous carbon spheres; the electrode material can be used as the positive electrode material for rechargeable near-neutral zinc-air batteries.

[0089] This application also provides a rechargeable near-neutral zinc-air battery, which includes a positive electrode, a negative electrode, an electrolyte and a separator;

[0090] Among them, the positive electrode includes the above electrode material; specifically, the positive electrode is obtained by mixing the macroporous carbon spheres, conductive agent, and binder of the present application into a film and then pressing it onto carbon paper; among them, the conductive agent is any one or a mixture of two or more of Cabot carbon black, Ketjen black, acetylene black, or Super P, and the binder is any one or a mixture of two or more of polytetrafluoroethylene, polyvinylidene fluoride, or Nafion solution.

[0091] The negative electrode is a zinc material, including zinc foil, zinc powder, zinc foam, or a composite material of zinc.

[0092] The electrolyte is an aqueous solution of zinc salt, such as an aqueous solution of zinc trifluoromethanesulfonate, zinc bis(trifluoromethylsulfonyl)imide, zinc acetate, or zinc sulfate; the separator includes a glass fiber separator, a polyethylene or polypropylene microporous membrane, or a composite separator including two or more of the above thin separators. The rechargeable near-neutral zinc-air battery of the present application can be assembled into a Swagelok-type battery or a button battery, with an energy efficiency of up to 78.7% and a cycle life of up to 650 h.

[0093] The following further illustrates the present application through examples.

[0094] Example 1

[0095] This example provides a method for preparing macroporous carbon spheres, including:

[0096] Add 0.2 g of F127 to 10 mL of an ethanol / water solution (volume ratio 1:1), stir for 10 minutes until the surfactant is completely dissolved to obtain a precursor solution;

[0097] Add 0.6 g of resorcinol and 0.72 mL of formaldehyde solution to the precursor solution, and stir vigorously until completely dissolved. Subsequently, at a stirring rate of 500 rpm, slowly add 1 mL of mesitylene to it, stir for 1 h to obtain a translucent microemulsion; after stirring for 0.5 h, add 0.4 g of L121 to it to form a uniform milky white emulsion; after stirring for 1 h, add 1.4 mL of ammonia water to the emulsion to initiate a polymerization reaction, react at room temperature for 12 h, then collect the solid phase by filtration, and dry it to obtain a brown F127 / L121 phenolic resin sphere composite.

[0098] Heat-treat the F127 / L121 phenolic resin sphere composite in a nitrogen atmosphere at 350 °C for 3 h to obtain macroporous phenolic resin spheres.

[0099] Heat the macroporous phenolic resin spheres to 1000 °C in a nitrogen atmosphere and hold for 2 h for carbonization to obtain macroporous carbon spheres.

[0100] Example 2

[0101] This embodiment provides a method for preparing macroporous carbon spheres, including:

[0102] Add 0.5 g of F127 to 10 mL of an ethanol / water solution (volume ratio 1:1), and stir for 10 minutes until the surfactant is completely dissolved to obtain a precursor solution.

[0103] Add 0.6 g of resorcinol and 0.72 mL of formaldehyde solution to the precursor solution, and stir vigorously until completely dissolved. Subsequently, slowly add 0.5 mL of mesitylene to it at a stirring rate of 500 rpm, and stir for 1 h to obtain a translucent microemulsion; after stirring for 0.5 h, add 0.1 g of L121 to it to form a uniform milky white emulsion; after stirring for 1 h, add 1.4 mL of triethanolamine to the emulsion to initiate the polymerization reaction, react at room temperature for 24 h, then collect the solid phase by filtration, and dry it to obtain a brown F127 / L121 phenolic resin sphere composite.

[0104] Heat-treat the F127 / L121 phenolic resin sphere composite in a nitrogen atmosphere at 400 °C for 3 h to obtain macroporous phenolic resin spheres.

[0105] Heat the macroporous phenolic resin spheres to 1000 °C in a nitrogen atmosphere and hold for 2 h for carbonization to obtain macroporous carbon spheres.

[0106] Example 3

[0107] This embodiment provides a method for preparing macroporous carbon spheres, including:

[0108] Add 0.4 g of F127 to 10 mL of an ethanol / water solution (volume ratio 1:1), and stir for 10 minutes until the surfactant is completely dissolved to obtain a precursor solution.

[0109] Add 0.6 g of resorcinol and 0.72 mL of formaldehyde solution to the precursor solution, and stir vigorously until completely dissolved. Subsequently, slowly add 0.75 mL of mesitylene to it at a stirring rate of 500 rpm, and stir for 1 h to obtain a translucent microemulsion; after stirring for 0.5 h, add 0.2 g of L121 to it to form a uniform milky white emulsion; after stirring for 1 h, add 1.4 mL of triethanolamine to the emulsion to initiate the polymerization reaction, react at room temperature for 24 h, then collect the solid phase by filtration, and dry it to obtain a brown F127 / L121 phenolic resin sphere composite.

[0110] Heat-treat the F127 / L121 phenolic resin sphere composite in a nitrogen atmosphere at 400 °C for 3 h to obtain macroporous phenolic resin spheres.

[0111] Heat the macroporous phenolic resin spheres to 1000 °C in a nitrogen atmosphere and hold for 2 h for carbonization to obtain macroporous carbon spheres.

[0112] Example 4

[0113] This example provides a method for preparing macroporous carbon spheres, including:

[0114] Add 0.2 g of F127 to 10 mL of an ethanol / water solution (volume ratio 1:1), stir for 10 minutes until the surfactant is completely dissolved to obtain a precursor solution;

[0115] Add 0.6 g of resorcinol and 0.72 mL of formaldehyde solution to the precursor solution, and stir vigorously until completely dissolved. Subsequently, at a stirring rate of 500 rpm, slowly add 2 mL of mesitylene to it, stir for 1 h to obtain a translucent microemulsion; after stirring for 0.5 h, add 0.8 g of L121 to it to form a uniform milky white emulsion; after stirring for 1 h, add 1.4 mL of ammonia water to the emulsion to initiate a polymerization reaction, react at room temperature for 24 h, then collect the solid phase by filtration, and dry it to obtain a brown F127 / L121 phenolic resin sphere composite.

[0116] Heat-treat the F127 / L121 phenolic resin sphere composite in a nitrogen atmosphere at 400 °C for 3 h to obtain macroporous phenolic resin spheres.

[0117] Heat the macroporous phenolic resin spheres to 1200 °C in a nitrogen atmosphere and hold for 5 h for carbonization to obtain macroporous carbon spheres.

[0118] Comparative Example 1

[0119] This example provides a method for preparing carbon spheres using only the first surfactant, including:

[0120] Add 0.5 g of F127 to 10 mL of an ethanol / water solution (volume ratio 1:1), stir for 10 minutes until the surfactant is completely dissolved to obtain a precursor solution;

[0121] Add 0.6 g of resorcinol and 0.72 mL of formaldehyde solution to the precursor solution, and stir vigorously until completely dissolved. Subsequently, at a stirring rate of 500 rpm, slowly add 0.5 mL of mesitylene to it, stir for 1 h, then add 1.4 mL of triethanolamine to initiate a polymerization reaction, react at room temperature for 24 h, then collect the solid phase by filtration, and dry it to obtain a brown F127 / phenolic resin sphere composite.

[0122] Heat-treat the F127 / phenolic resin sphere composite in a nitrogen atmosphere at 400 °C for 3 h to obtain phenolic resin spheres.

[0123] Heat the phenolic resin spheres to 1200 °C in a nitrogen atmosphere and hold for 5 h for carbonization to obtain carbon spheres.

[0124] The macroporous phenolic resin spheres and macroporous carbon spheres prepared in Example 1 were characterized to evaluate their morphological structures and properties, as follows:

[0125] 1. SEM test. Figure 1 is the SEM image of the macroporous phenolic resin spheres; Figure 2 is the high-magnification SEM image of the macroporous carbon spheres; Figure 3 is the large-scale SEM image of the macroporous carbon spheres.

[0126] From Figure 1 it can be seen that the macroporous phenolic resin spheres in Example 1 have a uniform spherical morphology and an open macroporous structure, with uniform spherical particle sizes and an average particle diameter of about 600 nm.

[0127] From Figure 2 it can be seen that the macroporous carbon spheres obtained by high-temperature carbonization of the macroporous phenolic resin spheres still retain their macroporous structures and have excellent stability; from Figure 3 it can be seen that the morphology of the macroporous carbon spheres is very uniform.

[0128] 2. Transmission electron microscopy test. Figure 4 is the high-magnification transmission electron microscopy image of the macroporous carbon spheres, Figure 5 is the high-magnification transmission electron microscopy image of the macroporous carbon spheres after ultra-thin sectioning.

[0129] From Figure 4 an open macroporous structure can be observed, and the particle diameter of the macroporous carbon spheres is about 400 nm.

[0130] Figure 5 Figure a in Figure 5 corresponds to the outermost edge of the macroporous carbon spheres, and open pores larger than 100 nm can be observed;

[0131] 3. Specific surface area

[0132] The nitrogen adsorption-desorption isotherm curve of the macroporous carbon spheres is as shown in Figure 6 . A hysteresis loop is observed in the pressure range of 0.5 - 1.0, indicating that it has both mesoporous and macroporous structures, with a specific surface area of 840 m 2 g -1 , and a pore volume of 1.1 cm 3 g -1 .

[0133] 4. Pore size distribution

[0134] The pore size distribution diagram of the macroporous carbon spheres is as shown in Figure 7 . From Figure 7 it can be seen that the pore size distribution range is 7 - 150 nm, and its most probable pore size is 40 - 50 nm.

[0135] The carbon spheres prepared in Examples 1-4 and Comparative Example 1 were subjected to scanning electron microscopy, transmission electron microscopy and pore size tests, and the results are as follows Figure 8 shown.

[0136] Among them, Figure 8 the three leftmost figures in Figure 8 i.e., figures a, e and i in Figure 8 are the SEM image, transmission electron microscopy image and pore size distribution image of the carbon spheres of Comparative Example 1, respectively; Figure 8 the three figures on the left side of the middle, i.e., Figure 8 figures b, f and j in Figure 8 are the SEM image, transmission electron microscopy image and pore size distribution image of the macroporous carbon spheres of Example 2, respectively; Figure 8 the three figures on the right side of the middle, i.e., Figure 8 figures c, g and k in

[0137] are the SEM image, transmission electron microscopy image and pore size distribution image of the macroporous carbon spheres of Example 3, respectively; Figure 8 the three rightmost figures in

[0138] i.e., figures d, h and l in

[0139] are the SEM image, transmission electron microscopy image and pore size distribution image of the carbon spheres of Example 1, respectively. Figure 9 As can be seen from Figure 9 the pore size of the carbon spheres in this application is achieved by adjusting the swelling degree of the micelles through the compounding of different surfactants. Specifically, from the SEM images and pore size distribution images of the carbon spheres in Example 2, Example 3 and Example 1, it can be seen that as the proportion of the second surfactant L121 increases, the swelling degree of the micelles gradually increases, the micelle size becomes larger, and finally the pore size of the obtained carbon spheres becomes larger. For example, the pore size of the carbon spheres obtained in Example 2 is 7-40 nm, and its most probable pore size is 17 nm; the pore size of the carbon spheres obtained in Example 3 reaches 7-70 nm, and its most probable pore size is 30 nm; while the pore size of the carbon spheres obtained in Example 1 reaches 7-150 nm, and its most probable pore size is 40-50 nm. Figure 9 In the comparative example, there is only the first surfactant F127 and no second surfactant L121. The swelling degree of the micelles for the organic solvent is relatively low, and only small-sized micelles can be obtained, resulting in a relatively small pore size of the sample, and its pore size is concentrated at about 7 nm.

[0140] The macroporous carbon spheres prepared in Example 1 were used as the positive electrode material of a near-neutral zinc-air battery. A Swagelok-type near-neutral zinc-air battery was assembled and its performance was tested as follows:

[0141] The macroporous carbon spheres prepared in Example 1 were mixed and ground with Cabot carbon black and polytetrafluoroethylene in a mass ratio of 80:10:10. Isopropyl alcohol was used as a dispersant. The above materials were mixed evenly, stirred into a film, and further cut into circular pieces with a diameter of 12 mm. It was rolled onto carbon paper of the same size to obtain the positive electrode sheet, and water and isopropyl alcohol were removed by vacuum drying at 100 °C. A 50-μm-thick zinc foil was used as the negative electrode (diameter 12 mm), a glass fiber membrane (Whatman GF / C) was used as the separator (diameter 14 mm), an aqueous solution of 1 M Zn(OAc)2 was used as the electrolyte, tin foil was used as the current collector of the zinc negative electrode, and a Swagelok-type battery mold was used to assemble a near-neutral zinc-air battery.

[0142] The above near-neutral zinc-air battery was subjected to charge-discharge testing at room temperature with 1 mAh cm -2 as the cut-off capacity, and its cycling performance is as Figure 10 shown. As can be Figure 10 seen, at a current density of 0.1 mA cm -2 , the battery polarization is very small and the energy density is as high as 78.7%. Even at a large current density of 10.0 mA cm -2 , the charging voltage is only 2 V, demonstrating the excellent rate performance of this material.

[0143] The above near-neutral zinc-air battery was subjected to cycling performance testing, and its cycling performance graph is as Figure 11 shown. It can stably cycle for 650 h at a current density of 0.5 mAcm -2 . This is due to the large-sized and highly open pore structure enabling the uniform deposition of inert discharge products inside the pores, ensuring efficient ion transport and gas diffusion, maintaining an excellent conductive network, and thus realizing the highly reversible generation and decomposition of discharge products.

[0144] Although this application has been described in detail in this specification with general descriptions and specific embodiments, based on this application, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of this application all fall within the scope claimed by this application.

Claims

1. A macroporous carbon sphere, characterized in that, It has a pore structure that diverges from the center; Its pore diameter is 7 to 150 nm, specific surface area is 80 to 1600 m 2 / g, and pore volume is 0.2 to 1.5 cm 3 / g.

2. The preparation method of the macroporous carbon spheres according to claim 1, characterized in that, Including: Dissolve the first surfactant in the composite solvent and stir evenly to obtain a precursor solution; Add a pore-expanding agent and a second surfactant to the precursor solution to obtain a homogeneous emulsion; Add a phenolic precursor and formaldehyde to the emulsion and stir evenly; then add a catalyst for polymerization reaction; after the reaction, collect the solid phase and perform heat treatment under an inert atmosphere to obtain macroporous phenolic resin spheres; Carry out carbonization treatment on the macroporous phenolic resin spheres under an inert atmosphere to obtain macroporous carbon spheres.

3. The preparation method according to claim 2, characterized in that, Both the first surfactant and the second surfactant are polyether-based nonionic surfactants; The second surfactant has a shorter hydrophilic block length than the first surfactant.

4. The preparation method according to claim 3, wherein The first surfactant includes at least one of F127, F108, or P105; The second surfactant is at least one of P123 or L121.

5. The preparation method according to claim 2, wherein The composite solvent is a mixture of ethanol and water, where the volume fraction of ethanol is 20 - 80%; And / or, The phenolic precursor includes at least one of phenol, resorcinol, m-aminophenol, o-aminophenol, or p-aminophenol; And / or, The pore-expanding agent is benzene and its derivatives, saturated aliphatic hydrocarbons, or olefinic compounds; And / or, The catalyst is at least one of ammonia water, fatty amines, alkanolamines, aromatic amines, amides, aromatic amines, or cycloaliphatic amines.

6. According to the preparation method described in claim 2, characterized in that Based on the composite solvent, the concentration of the first surfactant is 0.05 - 5 wt%, the concentration of the phenolic precursor is 0.01 - 1 M, and the concentration of the catalyst is 0.1 - 1.5 M; And / or, The molar ratio of formaldehyde to the phenolic precursor is (0.5 - 4):1; The mass ratio of the second surfactant to the first surfactant is (0.1 - 5):1; The mass ratio of the first surfactant to the pore-expanding agent is (0.05 - 0.5):

1.

7. According to the preparation method described in claim 2, characterized in that The temperature of the polymerization reaction is 15 - 80 °C; And / or, The temperature of the heat treatment is 300 - 500 °C; And / or, The temperature of the carbonization treatment is 700 - 1600 °C, and the time is 0.5 - 5 h; And / or, The inert atmosphere is a helium, neon, argon, nitrogen, or carbon dioxide atmosphere.

8. Application of the macroporous carbon spheres described in claim 1 or the macroporous carbon spheres prepared by the preparation method described in any one of claims 2 - 7 in a rechargeable near-neutral zinc-air battery.

9. An electrode material, characterized in that, It includes the macroporous carbon spheres described in claim 1 or the macroporous carbon spheres prepared by the preparation method described in any one of claims 2 - 7.

10. A rechargeable near-neutral zinc-air battery, characterized in that, Including a positive electrode, a negative electrode, an electrolyte, and a separator; The positive electrode includes the electrode material described in claim 9; The negative electrode is a zinc material; The electrolyte is an aqueous solution of zinc trifluoromethanesulfonate, zinc bis(trifluoromethylsulfonyl)imide, zinc acetate, or zinc sulfate; The separator includes at least one of a glass fiber separator, a polyethylene, or a polypropylene microporous membrane.

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