A metal-doped porous carbon, preparation method and application

Abstract

The present invention provides a metal-doped porous carbon, a preparation method and an application, belonging to the field of battery material preparation. By adding an activator and a crosslinking agent, during the curing process, the phenyl resin can be preliminarily carbonized under the action of the activator to form uniformly structured tiny pores, and crosslinked to form a three-dimensional pore structure under the combined action of the activator and the crosslinking agent, which is beneficial to maintaining the stability of the material structure during subsequent processing. Then, while pickling and removing impurities, more active sites are further formed on the surface and inside the pores of the material, which is further beneficial to more uniformly performing the reduction treatment inside the pores, making the pore structure more uniform. Furthermore, it is beneficial to form a porous carbon structure with stable structure, reduce defects after high-temperature carbonization treatment, and form a uniform and stable nano-pore structure after activation treatment, improving the compressive strength of the material. And when performing molten doping of the metal, the doping of the metal is more uniform, which can effectively improve the conductivity.

Description

Technical Field

[0001] The present invention belongs to the field of material preparation, and particularly relates to a metal-doped porous carbon, a preparation method and an application thereof. Background Art

[0002] With the continuous development of technology, the demand for high-performance materials is increasing day by day. Among many new materials, porous carbon materials have attracted much attention due to their unique properties.

[0003] Porous carbon is a carbon material with a rich pore structure, which endows it with characteristics such as a high specific surface area, good adsorption performance, excellent electrical conductivity and thermal stability, and is often used in the fields of energy, environmental protection, catalysis, as well as adsorption separation, biomedicine, food processing and other fields. Resin-based porous carbon has the advantages of easy precise control of pore structure, relatively high specific surface area, good chemical stability, easy processing and molding, wide raw material sources and relatively low cost. However, the resin-based porous carbon has a low conductivity, and its application in fields with extremely high conductivity requirements is limited.

[0004] The existing preparation methods of resin-based porous carbon mainly include processes such as activation method and template method. The activation method mainly uses gases such as water vapor and carbon dioxide as activators to contact with the carbonized material at high temperature for activation and pore formation to improve the specific surface area of the material, but the pore distribution of the material is uneven and the consistency is poor. Although the template method can orderly control the pore structure, the template preparation cost is high, and the prepared porous carbon still needs to be etched to remove the template, resulting in a high production cost and it is difficult to realize industrialization. Among them, the template method is divided into hard template method and soft template method. The hard template method is to first synthesize porous molecular sieve to obtain a carbon precursor, and then pour the carbon precursor into its pores to form a nano-organic matter / silicon composite material, and then through high-temperature carbonization and template etching technology, finally prepare a porous carbon material. The soft template method uses a surfactant as a template agent, and through the interaction between the surfactant and the carbon source, a porous structure is formed by self-assembly. However, it has disadvantages such as poor electron conductivity and low compressive strength, further damaging the electrical conductivity of the material.

[0005] In order to improve the performance of porous carbon materials, in the prior art, doping non-metals (nitrogen, boron, phosphorus, etc.) into the materials can improve the electron conductivity of the materials, but the improvement of the electron conductivity of the materials is limited, and the strong activity of non-metals will react with the electrolyte and other substances to reduce the first efficiency and storage performance of the energy storage device. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the present invention aims to provide a metal-doped porous carbon with high electron conductivity, uniform pore structure distribution and stable structure, a preparation method and an application thereof.

[0007] One of the purposes of the present invention is to provide a preparation method of metal-doped porous carbon, and the preparation method includes the following steps:

[0008] S1 First, cure a phenyl resin, an activator, and a crosslinking agent at 350 - 600 °C, then perform pickling, followed by vacuum drying, and then introduce a reducing mixed gas for reduction treatment to obtain an intermediate material;

[0009] S2 In an inert atmosphere, perform high-temperature carbonization treatment on the intermediate material at 1300 - 1500 °C, and then introduce steam for activation treatment to obtain porous carbon;

[0010] S3 In an inert atmosphere, melt-dope the porous carbon with a nano metal, and then perform passivation treatment to obtain metal-doped porous carbon.

[0011] Preferably, the mass ratio of the phenyl resin, the activator, and the crosslinking agent is 100:1 - 5:1 - 15.

[0012] Preferably, the time for the curing treatment is 1 - 6 h.

[0013] Preferably, the phenyl resin includes one or more of phenylphenol formaldehyde resin, xylene formaldehyde resin, phenol furfural resin, benzoguanamine resin, or resorcinol formaldehyde resin.

[0014] Preferably, the activator includes one or more of zinc chloride, zinc bromide, and zinc nitrate.

[0015] Preferably, the crosslinking agent includes one or more of 2-methylimidazole, 4,5-dimethylimidazole, 4-formylimidazole, 2-propylimidazole, or 2-phenylimidazole.

[0016] Preferably, the reducing mixed gas includes a reducing gas and nitrogen.

[0017] Preferably, the volume ratio of the reducing gas to nitrogen is 1 - 5:10.

[0018] Preferably, during the reduction treatment, the flow rate of the reducing mixed gas is 100 - 500 mL / min.

[0019] Preferably, the time for the reduction treatment is 1 - 10 h.

[0020] Preferably, the heating rate for the high-temperature carbonization treatment is 1 - 10 °C / min.

[0021] Preferably, the heat preservation time for the high-temperature carbonization treatment is 1 - 6 h.

[0022] Preferably, the temperature for the activation treatment is 1000 - 1200 °C.

[0023] Preferably, the flow rate of the water vapor is 100 - 500 mL / min.

[0024] Preferably, the time for the activation treatment is 30 - 300 min.

[0025] Preferably, the mass ratio of the porous carbon to the nano metal is 100:1 - 10.

[0026] Preferably, the heating temperature for the melt doping is 800 - 1200 °C.

[0027] Preferably, the heat preservation time for the melt doping is 30 - 120 min.

[0028] Preferably, the nano metal includes one or more of nano magnesium, nano lithium, nano nickel, or nano copper.

[0029] Preferably, the particle size of the nano metal is 1 - 5 μm.

[0030] Preferably, during the passivation treatment, the flow rate of the passivation gas is 10 - 100 mL / min.

[0031] Preferably, the time for the passivation treatment is 30 - 300 min.

[0032] Preferably, the passivation gas includes carbon dioxide and / or oxygen.

[0033] The second object of the present invention is to provide a metal-doped porous carbon obtained by the preparation method as described above, wherein the metal-doped porous carbon comprises 1 - 5 wt% of metal and 95 - 99 wt% of porous carbon.

[0034] Preferably, the specific surface area of the metal-doped porous carbon is 500 - 3000 m 2 / g, the pore volume is 0.5 - 3.0 cm 3 / g, the pore diameter is 1 - 20 nm, and the powder resistivity is 0.1 - 1 Ω·cm.

[0035] The third object of the present invention is to provide an application of the metal-doped porous carbon as described above in the field of secondary batteries.

[0036] The beneficial effects of the present invention include:

[0037] By adding an activator and a crosslinking agent, during the curing process, the phenyl resin can be preliminarily carbonized under the action of the activator to form tiny pores with uniform structure. At the same time, under the combined action of the activator and the crosslinking agent, crosslinking occurs to form a three-dimensional pore structure, which is beneficial to maintaining the stability of the material structure during subsequent processing and laying a foundation for subsequent pore development. Further, by pickling, the residual impurity elements are dissolved, and more active sites are formed on the surface and inside the pores of the material, which is further conducive to more uniformly performing the reduction treatment inside the pores, making the pore structure more uniform. Furthermore, it is beneficial to perform uniform and stable high-temperature carbonization treatment on the intermediate material to form a porous carbon structure with stable structure, reduce defects, and after activation treatment, form a uniform and stable nano-pore structure, improving the compressive strength of the material. The porous carbon material of the present invention has more and more uniform active sites. When further performing molten doping of metals, the doping of metals is more uniform, while improving the conductivity, it can further avoid causing pore blockage. Description of the Drawings

[0038] Figure 1 SEM image of the metal-doped porous carbon prepared in Example 1. Detailed Description of the Embodiments

[0039] In the following description, certain specific details are included to provide a comprehensive understanding of the various disclosed embodiments. However, those skilled in the relevant art will recognize that the embodiments can be implemented without one or more of these specific details, and other methods, components, materials, etc. can be used.

[0040] Unless otherwise required in the present invention, the words "comprising" and "including" should be interpreted in an open, inclusive sense, i.e., "including but not limited to".

[0041] As used throughout this specification, the phrase "in one embodiment" or "in an embodiment" or "in a preferred embodiment" or "in certain embodiments" means that at least one embodiment includes the specific reference elements, structures, or features associated with that embodiment. Thus, the phrases "in one embodiment" or "in an embodiment" or "in a preferred embodiment" or "in certain embodiments" that appear in different places throughout the specification do not necessarily all refer to the same embodiment. In addition, the specific elements, structures, or features can be combined in any suitable manner in one or more embodiments.

[0042] According to the first aspect of the present invention, a method for preparing a metal-doped porous carbon is provided. The preparation method includes the following steps:

[0043] S1 First, cure the phenyl resin, activator and crosslinking agent at 350 - 600 °C, then perform pickling, followed by vacuum drying, and then introduce a reducing gas mixture for reduction treatment to obtain an intermediate material;

[0044] S2 In an inert atmosphere, perform high-temperature carbonization treatment on the intermediate material at 1300 - 1500 °C, and then introduce steam for activation treatment to obtain porous carbon;

[0045] S3 In an inert atmosphere, melt-dope the porous carbon with nano-metal, and then perform passivation treatment to obtain metal-doped porous carbon.

[0046] In the present invention, in the curing treatment stage, the phenyl resin is cured with the activator and crosslinking agent at 350 - 600 °C. On the one hand, the activator can synergistically act with the crosslinking agent to promote the crosslinking between phenyl resins, forming a three-dimensional network structure and making the structure more stable; on the other hand, it can promote the low-temperature carbonization of phenyl resin at 350 - 600 °C to form uniformly structured tiny pores. The two work together to form a three-dimensional network pore structure with uniform structure, which is beneficial to maintaining the stability of the material structure during subsequent treatment processes and laying a foundation for subsequent pore development.

[0047] Furthermore, in the present invention, pickling is used to dissolve residual impurity elements and slightly etch the material, thereby exposing more active sites and introducing chemical groups such as hydroxyl and carboxyl groups. These active sites are more conducive to the subsequent reduction treatment, high-temperature carbonization treatment, activation treatment, and metal melt-doping of the material, and are beneficial to promoting the optimization of the material structure and the improvement of performance.

[0048] Specifically, hydrochloric acid can be used for pickling.

[0049] In the reduction treatment stage, the reduction reaction can be carried out more uniformly inside the pores for reduction treatment, adjusting the internal structure of the material to a certain extent, making the pore structure more open, forming an intermediate material with better pore structure uniformity, and further increasing the activity of the material.

[0050] In the high-temperature carbonization treatment stage, perform high-temperature carbonization treatment at 1300 - 1500 °C in an inert atmosphere. Specifically, the inert gas is nitrogen or helium. In this stage, a large amount of organic components in the material decompose, and non-carbon atoms escape in the form of gas. The formation of the three-dimensional network pore structure can prevent the collapse of the pore structure,

[0051] which is beneficial to maintaining the structural stability and the uniformity of the pore structure.

[0052] In the present invention, the temperature of the high-temperature carbonization treatment is, for example, 1300°C, 1320°C, 1350°C, 1380°C, 1400°C, 1430°C, 1450°C, 1480°C or 1500°C, as well as the point values between any two of the above.

[0053] In the activation treatment stage, water vapor reacts with the carbon material to etch the carbon skeleton, generating more micropores and mesopores, further increasing the pore volume and specific surface area, and forming a uniform and stable nano-porous structure. At the same time, the activation treatment can also optimize the possible pore surface, which is more conducive to the process of metal melting doping.

[0054] In the metal melting doping stage, the active sites of the porous carbon material of the present invention are more and more uniform. When further carrying out the melting doping of the metal, the doping of the metal is more uniform. While improving the conductivity, it can further avoid pore blockage. At the same time, the interaction between the nano-metal and the carbon can further enhance the structural stability of the material. After further passivation treatment, a passivation film is formed on the surface of the material and the pores, avoiding direct contact between the metal and the electrolyte, which is beneficial to reducing side reactions and ensuring the stability of the material performance.

[0055] In a preferred embodiment of the present invention, the mass ratio of the phenyl resin, the activator and the crosslinking agent is 100:1-5:1-15.

[0056] In the present invention, taking 100 parts by weight of the phenyl resin as an example, the activator is, for example, 1 part, 2 parts, 3 parts, 4 parts or 5 parts, and the crosslinking agent is, for example, 1 part, 3 parts, 5 parts, 7 parts, 9 parts, 10 parts, 13 parts or 15 parts, as well as the point values between any two of the above.

[0057] When the activator is less than 1 part, it is easy to cause poor development of the pore structure due to incomplete reaction, which in turn increases the carbon skeleton defects, has more closed pores, reduces the silicon storage performance of the material, and causes unstable product performance and poor consistency; when the activator is greater than 5 parts, it is easy to cause excessive reaction of the material to damage the structure, and it is also easy to cause the collapse of the pore structure during the high-temperature carbonization and activation processes, which may cause the originally orderly formed pore structure to merge into macropores, destroying the consistency of the material structure. At the same time, the formed pores are larger, reducing the compressive strength of the porous carbon; after excessive reaction, it is easy to obtain a disordered porous carbon structure. When carrying out nano-metal melting doping, the nano-metal is difficult to be uniformly dispersed in the material, and agglomeration is easy to occur, which in turn leads to unstable conductivity and local structure.

[0058] When the crosslinking agent is less than 1 part, it is likely to result in insufficient formation of crosslinking points, making the material structure relatively loose, with insufficient skeletal support. During subsequent processing, the material is prone to shrinkage and deformation, leading to unstable pore structures and poor mechanical strength of the material. It is also likely that due to the lack of sufficient crosslinking structure to stabilize the carbon skeleton, the rearrangement of carbon atoms to form a graphitized structure is restricted, reducing the degree of graphitization. This results in a decrease in the electrical conductivity of the material, which is not conducive to the rapid transmission of electrons when used as an electrode material, reducing the charge-discharge efficiency and power performance of the battery. During the nano-metal molten doping process, the insufficiently crosslinked porous carbon structure is difficult to form a strong interaction with the nano-metal. It is likely to cause the nano-metal to be difficult to disperse uniformly in the material, prone to agglomeration, and reducing the improvement effect of the nano-metal on the material properties. When the crosslinking agent is greater than 15 parts, it is likely to cause excessive crosslinking to hinder pore formation, thereby affecting the subsequent processing. The excessive crosslinking agent may also compete for reactions with other components such as the activator, affecting the normal curing and structure formation processes, resulting in the material properties not reaching the optimal state and increasing the uncertainty and control difficulty in the production process. At the same time, too much crosslinking agent forms more closed pore structures, reducing the silicon storage effect of the material and its specific capacity.

[0059] Preferably, the time for the curing treatment is 1 - 6 h, such as 1 h, 2 h, 3 h, 4 h, 5 h or 6 h, and the point values between any two of the above.

[0060] In the present invention, when the time for the curing treatment is less than 1 h, it is likely to result in incomplete reactions, leading to an imperfect three-dimensional network structure and unstable skeletal structure of the material. On the one hand, it affects the mechanical strength of the material, and the imperfect structure and uneven composition also affect the electrical conductivity of the material.

[0061] Preferably, the phenyl resin includes one or more of phenylphenol formaldehyde resin, xylene formaldehyde resin, phenol furfural resin, benzoguanamine resin or resorcinol formaldehyde resin.

[0062] In the present invention, the phenyl resin is, for example, phenylphenol formaldehyde resin, xylene formaldehyde resin, phenol furfural resin, benzoguanamine resin, resorcinol formaldehyde resin, a combination of phenylphenol formaldehyde resin and xylene formaldehyde resin, a combination of phenylphenol formaldehyde resin, xylene formaldehyde resin and phenol furfural resin, or a combination of benzoguanamine resin, resorcinol formaldehyde resin and phenylphenol formaldehyde resin.

[0063] Preferably, the activator includes one or more of zinc chloride, zinc bromide, zinc nitrate.

[0064] In the present invention, the activator is, for example, zinc chloride, zinc bromide, zinc nitrate, a combination of zinc chloride or zinc bromide, or a combination between zinc bromide and zinc nitrate.

[0065] Preferably, the crosslinking agent includes one or more of 2-methylimidazole, 4,5-dimethylimidazole, 4-formylimidazole, 2-propylimidazole or 2-phenylimidazole.

[0066] In the present invention, the crosslinking agent is, for example, 2-methylimidazole, 4,5-dimethylimidazole, 4-formylimidazole, 2-propylimidazole, 2-phenylimidazole, a combination of 2-methylimidazole and 4-formylimidazole, a combination of 2-methylimidazole and 2-phenylimidazole, or a combination of 2-methylimidazole, 4-formylimidazole and 2-phenylimidazole.

[0067] Preferably, the reducing mixed gas includes a reducing gas and nitrogen.

[0068] In the present invention, the reducing gas includes one of hydrogen, carbon monoxide or ammonia. The combination of nitrogen and the reducing gas can provide a stable inert atmosphere and an effective reduction effect.

[0069] Preferably, the volume ratio of the reducing gas to nitrogen is 1-5:10, and can be, for example, 1:10, 2:10, 3:10, 4:10 or 5:10.

[0070] In the present invention, when the volume ratio of the reducing gas to nitrogen is less than 1:10, it is likely to cause insufficient reduction reaction and low reaction efficiency, resulting in limited improvement in the chemical activity and performance of the material, and also weakening the adjustment effect on the internal structure of the material, making it difficult to effectively optimize the pore structure and improve the stability of the material. When the volume ratio of the reducing gas to nitrogen is greater than 5:10, it is likely to cause the reaction to be too intense, resulting in local overheating of the material, and then causing non-uniform changes in the material structure, possibly causing the pore structure to collapse or cracks to occur; at the same time, too much reducing gas leads to insufficient reaction of the reducing gas, resulting in waste of the reducing gas and an increase in its cost.

[0071] Preferably, during the reduction treatment, the flow rate of the reducing mixed gas is 100-500 mL / min, and can be, for example, 100 mL / min, 200 mL / min, 300 mL / min, 400 mL / min or 500 mL / min, as well as the point values between any two of the above.

[0072] Preferably, the time of the reduction treatment is 1-10 h, and can be, for example, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h, as well as the point values between any two of the above.

[0073] In the present invention, when the time of the reduction treatment is less than 1 h, it is likely to lead to incomplete reduction reaction, with limited improvement in the material properties, and it is also likely to cause unstable material properties and poor consistency; when the time of the reduction treatment is greater than 10 h, it is easy to change the chemical composition and structure of the material due to excessive reaction, making the structure unstable, with limited improvement in the properties and possible decline.

[0074] Preferably, the heating rate of the high-temperature carbonization treatment is 1-10 °C / min, such as 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min or 10 °C / min, and the point values between any two of the above.

[0075] Preferably, the heat preservation time of the high-temperature carbonization treatment is 1-6 h, such as 1 h, 2 h, 3 h, 4 h or 5 h, and the point values between any two of the above.

[0076] Preferably, the high-temperature carbonization treatment is carried out in a tube furnace.

[0077] Preferably, the temperature of the activation treatment is 1000-1200 °C, such as 1000 °C, 1020 °C, 1050 °C, 1070 °C, 1100 °C, 1120 °C, 1150 °C, 1170 °C or 1200 °C, and the point values between any two of the above.

[0078] In the present invention, when the activation treatment temperature is less than 1000 °C, it is difficult to sufficiently etch the carbon skeleton to form enough pores, which is likely to lead to insufficient pore generation. At the same time, it may also lead to uneven pore size distribution, with the situation that many micropores cannot be effectively formed and the proportion of mesopores is also unreasonable. It will also reduce the conductivity and structural stability of the material. At the same time, too low temperature causes insufficient discharge of hydrogen, oxygen and their impurities in the material, resulting in a large impedance; when the activation treatment temperature is greater than 1200 °C, it is easy to cause excessive etching and structural damage, and the originally formed pores may collapse or merge due to excessive reaction, making the pore structure lose uniformity and stability.

[0079] Preferably, the flow rate of the water vapor is 100-500 mL / min, such as 100 mL / min, 200 mL / min, 300 mL / min, 400 mL / min or 500 mL / min, and the point values between any two of the above.

[0080] Preferably, the time of the activation treatment is 30-300 min, such as 30 min, 60 min, 120 min, 180 min, 240 min or 300 min, and the point values between any two of the above.

[0081] Preferably, the mass ratio of the porous carbon to the nano-metal is 100:1 - 10, for example, it can be 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9 or 100:10.

[0082] In the present invention, when the mass ratio of the porous carbon to the nano-metal is less than 100:1, it is difficult for the nano-metal to form a continuous conductive network in the porous carbon, and the improvement effect on the conductivity of the material is limited, and the improvement of the structural stability is not obvious; when the mass ratio of the porous carbon to the nano-metal is greater than 100:10, during the preparation process, the nano-metal particles are more likely to agglomerate, and it is difficult to be uniformly dispersed in the porous carbon. This not only reduces the effective utilization rate of the nano-metal, but also may lead to non-uniform local performance. The presence of a large amount of nano-metal may interfere with the formation and stability of the porous carbon skeleton. During the high-temperature melting doping process, too much nano-metal may react excessively with carbon, changing the structural morphology of carbon, resulting in defects or discontinuities in the carbon skeleton, which will reduce the mechanical strength and structural stability of the material, making the material more likely to crack or be damaged during use, affecting its long-term performance and reliability.

[0083] Preferably, the heating temperature of the melting doping is 800 - 1200 °C, for example, it can be 800 °C, 850 °C, 900 °C, 950 °C, 1000 °C, 1050 °C, 1100 °C, 1150 °C or 1200 °C, as well as the point values between any two of the above.

[0084] Preferably, the heat preservation time of the melting doping is 30 - 120 min, for example, it can be 30 min, 50 min, 70 min, 90 min, 100 min or 120 min, as well as the point values between any two of the above.

[0085] In the present invention, if the heat preservation time of the melting doping is less than 30 min, it may lead to non-uniform dispersion of the nano-metal and insufficient combination with the porous carbon, and the improvement of the material performance is limited; when the heat preservation time is greater than 120 min, it may cause the uniformly dispersed nano-metal to agglomerate again, and may also damage the porous carbon structure.

[0086] Preferably, the nano-metal includes one or several of nano-magnesium, nano-lithium, nano-nickel or nano-copper.

[0087] Preferably, the particle size of the nano-metal is 1 - 5 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, as well as the point values between any two of the above.

[0088] In the present invention, nano-metals with a particle size of 1-5 μm are used, which are relatively well-matched with the pore structure size of the porous carbon described in the present invention. In the molten state, the nano-metals can smoothly enter the pores of the porous carbon and be evenly distributed therein, forming a good composite structure with the porous carbon. This helps to fully utilize the respective advantages of the nano-metals and the porous carbon, improve the comprehensive performance of the material, simplify the process control difficulty in the preparation process, and improve the preparation efficiency.

[0089] Preferably, during the passivation treatment, the flow rate of the passivation gas is 10-100 mL / min, for example, it can be 10 mL / min, 20 mL / min, 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min or 100 mL / min, as well as the point values between any two of the above.

[0090] Preferably, the time of the passivation treatment is 30-300 min, for example, it can be 30 min, 60 min, 120 min, 180 min, 240 min or 300 min, as well as the point values between any two of the above.

[0091] Preferably, the passivation gas includes carbon dioxide and / or oxygen.

[0092] Preferably, both the molten doping and the passivation treatment are carried out in a tubular furnace.

[0093] In a preferred embodiment of the present invention, the preparation method includes the following steps:

[0094] S1 According to the mass ratio of phenyl resin: activator: crosslinking agent = 100:1-5:5-15, mix the phenyl resin, activator, and crosslinking agent evenly, carry out solid treatment at a temperature of 350-600 °C for 1-6 h, then pickle the obtained material with 0.1 mol / L hydrochloric acid, vacuum dry at 80 °C, and then introduce a reducing mixed gas, and carry out reduction treatment at a flow rate of 100-500 mL / min for 1-10 h to obtain an intermediate material;

[0095] S2 Transfer the intermediate material to a tubular furnace, first introduce nitrogen to exhaust the air in the tube, then heat up to 1300-1500 °C for high-temperature carbonization treatment for 1-6 h, then cool down to 1000-1200 °C, introduce water vapor, and carry out activation treatment at a flow rate of 100-500 mL / min for 30-300 min to obtain a porous carbon material;

[0096] S3 Mix the porous carbon material and the nano-metal evenly according to the mass ratio of porous carbon material:nano-metal = 100:1 - 10, transfer the mixture to a tube furnace, first introduce nitrogen to expel the air in the tube, then heat to 800 - 1200 °C for melting and keep the temperature for 0.5 - 2 h, and then introduce a passivation gas for passivation treatment at a flow rate of 10 - 100 mL / min for 30 - 300 min to obtain metal-doped porous carbon.

[0097] According to the second aspect of the present invention, there is provided a metal-doped porous carbon obtained by the preparation method as described in the first aspect. The metal-doped porous carbon comprises 1 - 5 wt% of metal and 95 - 99 wt% of porous carbon.

[0098] In the present invention, the metal is, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt% or 5 wt%, and the point values between any two of the above. The porous carbon is, for example, 95 wt%, 96 wt%, 97 wt%, 98 wt% or 99 wt%, and the point values between any two of the above.

[0099] Preferably, the specific surface area of the metal-doped porous carbon is 500 - 3000 m 2 / g, the pore volume is 0.5 - 3.0 cm 3 / g, the pore diameter is 1 - 20 nm, and the powder resistivity is 0.1 - 1 Ω·cm.

[0100] According to the third aspect of the present invention, there is provided an application of the metal-doped porous carbon as described in the second aspect in the field of secondary batteries.

[0101] Preferably, the secondary battery includes a sodium battery or a lithium battery.

[0102] The numerical ranges described in the present invention include not only the above-listed point values, but also any point values between the above numerical ranges not listed. Due to space limitations and for the sake of brevity, the specific point values included in the ranges of the present invention are not exhaustively listed.

[0103] Examples

[0104] The present invention will be further described in detail below with reference to examples. It can be understood that the specific examples described herein are only for explaining the relevant invention and not for limiting the invention. It should be noted that, without conflict, the examples in the present invention and the features in the examples can be combined with each other.

[0105] In the following examples, unless otherwise specified, each raw material component is a commercially available product.

[0106] Example 1

[0107] A preparation method of metal-doped porous carbon, comprising the following steps:

[0108] After mixing 100 g of phenylphenol formaldehyde resin, 3 g of zinc chloride, and 10 g of 2-methylimidazole evenly, the mixture is cured at 500 °C for 3 h. Then, the obtained material is added to 1000 g of 0.1 mol / L hydrochloric acid and pickled three times, followed by vacuum drying at 80 °C for 24 h. After that, a reducing gas mixture with a volume ratio of carbon monoxide to nitrogen of 3:10 is introduced, and reduction treatment is carried out at a flow rate of 300 mL / min for 300 min to obtain an intermediate material;

[0109] Transfer the intermediate material to a tubular furnace, introduce nitrogen to exhaust the air in the tube, then heat it to 1400 °C at a heating rate of 5 °C / min and perform high-temperature carbonization treatment for 3 h. Then, cool it down to 1100 °C, introduce steam, and carry out activation treatment at a flow rate of 300 mL / min for 150 min to obtain porous carbon;

[0110] Mix 100 g of porous carbon and 5 g of nano lithium powder evenly, transfer them to a tubular furnace, introduce nitrogen to exhaust the air in the tube, then heat it to 950 °C, melt and keep it warm for 1 h, and then introduce carbon dioxide to passivate its surface at a flow rate of 50 mL / min for 150 min to obtain metal-doped porous carbon.

[0111] Example 2

[0112] A preparation method of metal-doped porous carbon, comprising the following steps:

[0113] After mixing 100 g of xylene formaldehyde resin, 1 g of zinc bromide, and 5 g of 4,5-dimethylimidazole evenly, the mixture is cured at 350 °C for 6 h. Then, the obtained material is added to 1000 g of 0.1 mol / L hydrochloric acid for pickling three times, followed by vacuum drying at 80 °C for 24 h. After that, a reducing gas mixture with a volume ratio of hydrogen to nitrogen of 1:10 is introduced, and reduction treatment is carried out at a flow rate of 100 mL / min for 600 min to obtain an intermediate material;

[0114] Transfer the intermediate material to a tubular furnace, introduce nitrogen to exhaust the air in the tube, then heat it to 1300 °C at a heating rate of 1 °C / min and perform high-temperature carbonization treatment for 6 h. Then, cool it down to 1000 °C, introduce steam, and carry out activation treatment at a flow rate of 100 mL / min for 300 min to obtain porous carbon;

[0115] Mix 100 g of porous carbon and 1 g of nano magnesium powder evenly, transfer them to a tubular furnace, introduce nitrogen to exhaust the air in the tube, then heat it to 800 °C, melt and keep it warm for 2 h, and then introduce oxygen to passivate its surface at a flow rate of 10 mL / min for 300 min to obtain metal-doped porous carbon.

[0116] Example 3

[0117] A preparation method of metal-doped porous carbon, comprising the following steps:

[0118] S1 After uniformly mixing 100 g of phenol-furfural resin, 5 g of zinc nitrate, and 15 g of 4-formylimidazole, curing treatment is carried out at a temperature of 600 °C for 1 h. Then, the obtained material is added to 1000 g of 0.1 mol / L hydrochloric acid for pickling three times, and then vacuum dried at 80 °C for 24 h. Then, a reducing mixed gas with a volume ratio of carbon monoxide to nitrogen of 5:10 is introduced, and reduction treatment is carried out at a flow rate of 500 mL / min for 60 min to obtain an intermediate material;

[0119] S2 Transfer the intermediate material to a tubular furnace, introduce nitrogen to discharge the air in the tube, then heat it to 1500 °C at a heating rate of 10 °C / min for high-temperature carbonization treatment for 1 h, then cool it to 1200 °C, introduce steam gas, and carry out activation treatment at a flow rate of 500 mL / min for 30 min to obtain porous carbon;

[0120] S3 Uniformly mix 100 g of porous carbon with 10 g of nano-nickel, and transfer it to a tubular furnace. After introducing nitrogen to discharge the air in the tube, heat it to 1200 °C for melting and keep it warm for 0.5 h, then introduce oxygen, and carry out surface passivation treatment at a flow rate of 100 mL / min for 30 min to obtain metal-doped porous carbon.

[0121] Example 4

[0122] Different from Example 1, in step S1, 1 g of zinc chloride and 5 g of 2-methylimidazole are used, and the others are the same as in Example 1.

[0123] Example 5

[0124] Different from Example 1, in step S1, 5 g of zinc chloride and 15 g of 2-methylimidazole are used, and the others are the same as in Example 1.

[0125] Example 6

[0126] Different from Example 1, in step S1, curing treatment is carried out at 350 °C for 6 h, and the others are the same as in Example 1.

[0127] Example 7

[0128] Different from Example 1, in step S1, curing treatment is carried out at 600 °C for 1 h, and the others are the same as in Example 1.

[0129] Example 8

[0130] Different from Example 1, in step S1, the volume ratio of carbon monoxide to nitrogen is 1:10, and the others are the same as in Example 1.

[0131] Example 9

[0132] Different from Example 1, the volume ratio of carbon monoxide to nitrogen in step S1 is 5:10, and the others are the same as in Example 1.

[0133] Example 10

[0134] Different from Example 1, the temperature of the high-temperature carbonization treatment in step S2 is 1300 °C, and the time of the high-temperature carbonization treatment is 6 h, and the others are the same as in Example 1.

[0135] Example 11

[0136] Different from Example 1, the temperature of the high-temperature carbonization treatment in step S2 is 1500 °C, and the time of the high-temperature carbonization treatment is 1 h, and the others are the same as in Example 1.

[0137] Example 12

[0138] Different from Example 1, the activation treatment temperature in step S2 is 1000 °C, and the others are the same as in Example 1.

[0139] Example 13

[0140] Different from Example 1, the activation treatment temperature in step S2 is 1200 °C, and the others are the same as in Example 1.

[0141] Example 14

[0142] Different from Example 1, 1 g of nano-lithium powder is used in step S3, and the others are the same as in Example 1.

[0143] Example 15

[0144] Different from Example 1, 10 g of nano-lithium powder is used in step S3, and the others are the same as in Example 1.

[0145] Comparative Example 1

[0146] Different from Example 1, no nano-lithium powder is added in step S3, and the others are the same as in Example 1.

[0147] Comparative Example 2

[0148] Different from Example 1, zinc chloride and 2-methylimidazole are not added in step S1, and the others are the same as in Example 1.

[0149] Performance Test

[0150] 1. Scanning Electron Microscope (SEM) Test:

[0151] The SEM photograph of the metal-doped porous carbon prepared in Example 1 is asFigure 1 As shown by Figure 1 it can be seen that the material presents a granular structure with a uniform size distribution, and the particle size ranges from 5 to 10 μm.

[0152] 2. Physical and chemical properties and coin cell tests:

[0153] 2.1 Physical and chemical property tests:

[0154] Refer to the national standard GB / T - 38949 - 2020 "Standard Particle Method for Measuring the Pore Size of Porous Membranes" to test the pore volume and pore diameter of the porous carbon obtained in Examples 1 - 15 and Comparative Examples 1 - 2;

[0155] And in accordance with the national standard GB / T - 24533 - 2019 "Graphite for Lithium - Ion Battery Anode Materials - Graphite", test its particle size D50, specific surface area and tapped density;

[0156] And use a four - probe tester to test the powder conductivity of each porous carbon material;

[0157] The above test results are shown in Table 1;

[0158] Use pressure - specific surface area to test the compressive ability of the material, that is, by applying a certain pressure to cause a change in the specific surface area of the material to judge the compressive ability of the material.

[0159] The test results are shown in Table 2.

[0160] 2.2 Coin cell performance tests:

[0161] Use the metal - doped porous carbon corresponding to Examples 1 - 15 and Comparative Examples 1 - 2 as the anode material of the lithium - ion battery to prepare a coin cell according to the following method:

[0162] Add a binder, a conductive agent and a solvent to each corresponding metal - doped porous carbon, stir to make a slurry, coat it on a copper foil, and obtain a negative electrode sheet after drying and rolling; the binder used is LA132, the conductive agent is SP (conductive carbon black), the solvent is NMP (N - methylpyrrolidone), and the dosage ratio of metal - doped porous carbon: SP: LA132: NMP is 80 g: 15 g: 15 g: 300 mL; the electrolyte is a solution with LiPF6 as the electrolyte, with a concentration of 1 mol / L. Among them, the solvent uses a mixture of EC and DEC with a volume ratio of 1:1; the metal lithium sheet is the counter electrode, and the separator uses a polypropylene (PP) membrane.

[0163] Each coin cell is assembled in a glove box filled with argon gas, and then the following performance tests are carried out:

[0164] Electrochemical performance test: Specifically, the electrochemical performance was tested on a Wuhan Blue Electric CT2001A battery tester. The charge-discharge voltage range was 0.005 V to 2.0 V, and the charge-discharge rate was 0.1 C. The discharge specific capacity and the first efficiency of the corresponding button cell were tested. At the same time, the normal-temperature charge DCR and the cycle performance test (0.1 C / 0.1 C, 100 cycles) of the corresponding button cell were tested; and the diffusion coefficient of the material was tested by GITT;

[0165] The test results are shown in Table 3.

[0166] Table 1 Physicochemical property tests of Examples 1-15 and Comparative Examples 1-2

[0167]

[0168] Table 2 Button cell performance test

[0169]

[0170] As can be seen from Table 1 and Table 2, Examples 1-15 have low powder resistivity and high first efficiency. This is because the doped metal in the examples improves the electronic conductivity of the material, and by adding a pore-forming agent in the resin, the pore volume and pore diameter of the material are increased, the specific surface area is increased, the liquid absorption capacity of the material is improved, and the diffusion coefficient of the material is improved.

[0171] Table 3 Compressive capacity tests of Examples 1-15 and Comparative Examples 1-2

[0172]

[0173] As can be seen from Table 3, after applying stepped pressure, the increase in the specific surface area of the example material is small, indicating that the material has strong compressive capacity under high pressure. The reason is that the doped metal elements in the example material improve the compressive capacity of the material.

[0174] The applicant declares that the present invention uses the above examples to illustrate the process method of the present invention, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of the raw materials selected for the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for preparing metal-doped porous carbon, characterized in that: The preparation method comprises the following steps: S1 first cures the phenyl resin, activator and cross-linking agent at 350-600°C, then acid washes, vacuum dries, and then introduces a reducing mixed gas for reduction treatment to obtain an intermediate material; The reducing mixed gas includes reducing gas and nitrogen, the volume ratio of the reducing gas to nitrogen is 1-5:10, the flow rate of the reducing mixed gas is 100-500 mL / min, and the reduction treatment time is 1-10 h; S2, in an inert atmosphere, subjecting the intermediate material to a high-temperature carbonization treatment at 1300-1500° C., and then introducing water vapor for activation treatment to obtain porous carbon; S3: in an inert atmosphere, melt-doping the porous carbon with nano-metal, and then performing a passivation treatment to obtain metal-doped porous carbon; The mass ratio of the phenyl resin, the activator and the cross-linking agent is 100:1-5:1-15, and the curing time is 1-6h; The phenyl resin includes one or more of phenylphenol formaldehyde resin, xylene formaldehyde resin, phenol furfural resin, benzoguanamine resin or resorcinol formaldehyde resin; The activator includes one or more of zinc chloride, zinc bromide and zinc nitrate; The cross-linking agent includes one or more of 2-methylimidazole, 4,5-dimethylimidazole, 4-formylimidazole, 2-propylimidazole or 2-phenylimidazole; The activation treatment temperature is 1000-1200°C, the water vapor flow rate is 100-500mL / min, and the activation treatment time is 30-300min; The mass ratio of the porous carbon to the nano-metal is 100:1-10, the heating temperature of the melt doping is 800-1200° C., and the holding time of the melt doping is 30-120 min; The nano metal includes one or more of nano magnesium, nano lithium, nano nickel or nano copper, and the particle size of the nano metal is 1-5 μm.

2. The preparation method according to claim 1, characterized in that The heating rate of the high temperature carbonization treatment is 1-10°C / min, and the heat preservation time is 1-6h.

3. The preparation method according to claim 1, characterized in that: During the passivation treatment, the passivation gas flow rate is 10-100 mL / min, the passivation treatment time is 30-300 min, and the passivation gas includes carbon dioxide and / or oxygen.

4. A metal-doped porous carbon prepared by the preparation method according to any one of claims 1 to 3, characterized in that: The metal-doped porous carbon comprises 1-5 wt % of metal and 95-99 wt % of porous carbon.

5. The metal-doped porous carbon according to claim 4, characterized in that: The specific surface area of ​​the metal-doped porous carbon is 500-3000 m 2 / g, pore volume is 0.5-3.0cm 3 / g, pore size is 1-20nm, and powder resistivity is 0.1-1Ω·cm.

6. Use of the metal-doped porous carbon as claimed in claim 4 or 5 in the field of secondary batteries.

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