A porous carbon material with a half-pit platform type aperture structure, a preparation method and applications thereof

Abstract

The application provides a preparation method of a porous carbon material with a semi-porous platform type pore structure, and comprises the following steps: performing a hydrothermal reaction on alkali lignin, a polyamine and a formaldehyde solution to obtain aminated alkali lignin; performing a cross-linking reaction on the aminated alkali lignin and a binary aldehyde mixture to obtain a precursor; uniformly mixing the precursor with a pore former, carbonizing and activating the mixture to obtain the porous carbon material with the semi-porous platform type pore structure; and the polyamine is selected from one or a combination of two or more of diethylenetriamine, triethylenetetramine and tetraethylenepentamine, and the polyamine is preferably tetraethylenepentamine. The application first grafts polyamines on the surface of alkali lignin through a Mannich reaction, then uses a binary aldehyde mixture of an aliphatic binary aldehyde and a binary aldehyde thiofuran derivative as a cross-linking agent, performs cross-linking and solidification on the alkali lignin through the reaction between aldehyde groups and amino groups, forms a complex highly cross-linked structure, reduces the generation of defects during carbonization and pyrolysis of the alkali lignin, and improves the ability to inhibit the volume expansion of silicon.

Description

Technical Field

[0001] The present invention belongs to the technical field of porous carbon materials, and in particular relates to a porous carbon material with a half-slope platform-type pore structure, a preparation method and an application thereof. Background Art

[0002] With the rapid development of lithium-ion batteries, the development of high-energy-density lithium-ion battery anode materials has become an urgent need in the current lithium-ion battery field. Because single-element silicon has the highest theoretical lithium storage capacity (about 4200mAh / g) and a low lithium desorption voltage platform (0.4-0.5V), it is considered to be one of the most promising anode materials to replace graphite. However, silicon anodes have been slow to be commercialized. This is because silicon produces a huge volume effect during the lithium desorption process. Silicon particles break or even pulverize due to the huge stress, which in turn causes the active material on the silicon electrode to pulverize and peel off, resulting in a loss of electrical contact between particles and between particles and current collectors, which leads to a sharp decline in battery capacity or even complete failure.

[0003] To solve this problem, researchers have conducted a lot of research on suppressing / reducing the volume effect of silicon and improving its electrical conductivity. Among them, dispersed silicon-carbon composite materials are one of the current research hotspots. Dispersed silicon-carbon composite materials, also known as molecular contact type, refer to the silicon-carbon materials in the composite material in molecular form. Silicon is highly dispersed in the carbon layer. The carbon material acts as a dispersed matrix, which can not only limit the volume change of silicon, but also serve as a conductive network to maintain good electrical contact between the electrodes during the charge and discharge process. For example, patent CN103840140B discloses a porous carbon-silicon composite material and its preparation method, patent CN116742002A discloses a silicon-carbon composite material and its preparation method and application, and lithium-ion secondary battery.

[0004] The porous carbon-silicon composite materials prepared above mostly use sucrose, glucose, polyvinyl chloride, asphalt, polyacrylonitrile, starch, etc. as precursors, which are pyrolyzed to obtain dispersed matrix porous carbon materials, and then vapor deposited to obtain a relatively ideal dispersed system. This composite form can inhibit the volume expansion of silicon, thereby maintaining good structural stability and cycle capacity of the electrode.

[0005] However, in recent years, with the continuous development of industrial society, the large-scale development and utilization of non-renewable petrochemical resources has caused resource crises, environmental pollution and energy problems that have seriously restricted the sustainable development of human society. The efficient development of natural renewable green biomass resources and their application in new energy materials with excellent performance, low cost, greenness and high efficiency is one of the main research and development trends at present. Lignin is a very abundant natural renewable biomass resource. Its content in plants is second only to cellulose. Its molecular structure has a three-dimensional network characteristic and is rich in a large number of aromatic groups and oxygen-containing functional groups. The carbon content is more than 60%. At present, the comprehensive utilization rate of industrial lignin from the pulp and paper and biorefining industries is only about 10%. Most of it is discharged as waste or burned as low-value fuel. If its carbonization and pyrolysis are used as a dispersed matrix - porous carbon material for dispersed silicon-carbon composite materials, it can not only achieve effective utilization of resources but also alleviate environmental pollution problems. Although lignin has three-dimensional network characteristics, it is not a highly cross-linked structure. During carbonization and pyrolysis, it is easy for local areas to lose stability, and the overall structure will shrink unevenly, leading to the formation of cracks, holes and even collapse. If this porous carbon material is used as a dispersed matrix for dispersed silicon-carbon composite materials, there are problems such as low strength, inability to effectively suppress the volume expansion of silicon, and poor cycle performance.

[0006] Therefore, it is necessary to modify lignin to prepare dispersed silicon-carbon composite materials that can inhibit the volume expansion of silicon and maintain good structural stability and cycle capacity of the electrode. Summary of the Invention

[0007] To solve the above problems, the present invention provides a porous carbon material with a half-slope platform-type pore structure, a preparation method and an application. The present invention first uses alkali lignin, polyamine and formaldehyde solution as raw materials to obtain amino-alkali lignin by Mannich reaction, then cross-links it with a dialdehyde derivative as a cross-linking agent, and finally mixes it with a porogen to carbonize and activate it to obtain a porous carbon material with a half-slope platform-type pore structure. The dispersed silicon-carbon composite material obtained by depositing silicon on this porous carbon material through chemical vapor deposition technology has a strong ability to inhibit the volume expansion of silicon and can maintain good structural stability and cycle capacity of the electrode.

[0008] In order to achieve the above objectives, the following technical solutions are adopted:

[0009] A method for preparing a porous carbon material with a semi-slope platform pore structure comprises the following steps:

[0010] 2) adding alkali lignin and polyamine to water, adjusting the pH, stirring until completely dissolved, adding formaldehyde solution under stirring to carry out hydrothermal reaction, adding isopropanol after the reaction is completed until no precipitation is produced, filtering, washing, and drying to obtain amination alkali lignin;

[0011] 2) dissolving the amination alkali lignin in an organic solvent, adding a dialdehyde mixture, heating to reflux to carry out a cross-linking reaction, and filtering, washing, drying, and grinding after the reaction to obtain a precursor;

[0012] 3) The precursor and the porogen are mixed uniformly, and then carbonized under an inert atmosphere. The carbonized material is then mixed with an alkali solution and activated in an inert atmosphere, and then cooled, acid-washed, washed with water, and dried to obtain a porous carbon material with a semi-slope platform pore structure;

[0013] In step 1), the polyamine is selected from one or a combination of two or more of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine, preferably tetraethylenepentamine.

[0014] In step 2), the dialdehyde derivative is a mixture of an aliphatic dialdehyde and a dialdehyde-thiophene derivative in a mass ratio of 5:7-10.

[0015] The porous carbon material prepared by the above method is a hierarchical porous structure with coexisting micro / mesopores. Its mesoporous area is small and has a broad peak distribution, that is, there is a half-slope platform-type mesoporous transition zone between the micropores and the macropores. This pore structure has good connectivity, and the silicon source gas can smoothly diffuse into the micropores deep inside the material, making full use of all adsorption sites, improving the dispersion uniformity of silicon particles in the porous carbon material, effectively reducing the generation of local defects, maintaining the stability of the electrode structure, and improving the cycle stability of the battery.

[0016] The alkali lignin preparation method in step 1) is not particularly limited and can be prepared by any method commonly used in the art. It can be prepared by acid precipitation of bamboo pulp or straw pulp alkaline papermaking black liquor. Specifically, the pH of the bamboo pulp or straw pulp alkaline papermaking black liquor is adjusted to 7-9 with an inorganic acid, filtered, and the filtrate is collected; the pH is then further adjusted to 2-3 with an inorganic acid, stirred at 70-100°C for 6-9 hours, filtered, washed with water 2-3 times, and dried to obtain the alkali lignin. The mass volume ratio of the alkali lignin to water is 1g:20-40mL. The mass ratio of the alkali lignin, polyamine, and formaldehyde solution is 15-20:4-6:5-8. The pH is adjusted to 10-11 using an alkali solution with a concentration of 0.5-1 mol / L, selected from one or a combination of NaOH and KOH solutions. The formaldehyde solution has a concentration of 30-40 wt%. The hydrothermal reaction temperature is 40-80°C, and the reaction time is 1-3 hours. The washing step is washing with water until the mixture becomes neutral. The drying step is drying at 60-80° C. until the mixture becomes constant weight.

[0017] The mass ratio of the dialdehyde mixture in step 2) to the polyamine in step 1) is 0.5-0.8:1. The aliphatic dialdehyde is a C8-C12 aliphatic dialdehyde selected from one or a combination of two or more of heptanedialdehyde, octanedial, nonanedialdehyde, and dodecanedial, preferably dodecanedial. The aldehyde thiophene derivative is selected from one or a combination of two or more of 3,4-thiophene dicarboxaldehyde, 2,3-thiophene dicarboxaldehyde, 2,2'-bithiophene-5,5'-dicarboxaldehyde, and 2,2':5',2"-terthiophene-5,5"-dicarboxaldehyde, preferably 2,2':5',2"-terthiophene-5,5"-dicarboxaldehyde. The reaction time is 4-6 hours. The organic solvent is selected from one or a combination of two or more of chloroform, pyridine, dichloromethane, ethanol, acetone, dioxane, and ethyl acetate, preferably a mixed solvent of dioxane and dichloromethane in a volume ratio of 7:2-4, preferably 7:3. The grinding is performed to grind the mixture to an average particle size of 40-80 mesh.

[0018] In step 3), the mass ratio of the precursor to the porogen is 1:1-2. The porogen is selected from one or a combination of two or more of ammonium carbonate, urea, ammonium bicarbonate, ammonium formate, ammonium acetate, and ammonium oxalate. The carbonization is performed by heating the temperature to 400-500°C at a rate of 5-10°C / min and maintaining the temperature for 1-3 hours; the alkali solution is one or a combination of two or more of NaOH and KOH solutions with a concentration of 10-30wt%. The mass volume ratio of the carbonized material to the alkali solution is 1g:1-4mL. The activation is performed by heating the temperature to 500-800°C at a rate of 1-20°C / min and maintaining the temperature for 0.5-3 hours. The cooling is performed by cooling to room temperature. The pickling is performed by washing 1-3 times with a hydrochloric acid solution with a concentration of 0.5-1.5 mol / L, and the water washing is performed by washing until neutral. The drying is performed at 60-100°C to constant weight.

[0019] A porous carbon material with a half-slope platform pore structure is prepared by the above-mentioned method for preparing a porous carbon material with a half-slope platform pore structure.

[0020] A method for preparing a dispersed silicon-carbon composite material comprises the following steps: evacuating a chemical vapor deposition device, placing the porous carbon material with a semi-slope platform pore structure in a chemical vapor deposition chamber, introducing a silicon source gas to perform vapor deposition of silicon, and obtaining the dispersed silicon-carbon composite material.

[0021] The temperature in the chemical vapor deposition chamber is 500-600°C. The mixed gas is introduced for 1-4 hours at a flow rate of 120-180 mL / min. The pressure in the chemical vapor deposition chamber is 0.1-0.3 MPa. The silicon source gas and the inert gas are mixed in a volume ratio of 5-10:90-95. The silicon source gas is selected from monosilane, disilane, or a combination of two or more. The inert gas is not particularly limited and includes, but is not limited to, argon and nitrogen, or a combination of two or more.

[0022] A lithium-ion battery comprises a negative electrode, wherein the negative electrode comprises the above-mentioned dispersed silicon-carbon composite material.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention first grafts a polyamine onto the surface of alkali lignin through a Mannich reaction, then uses a dialdehyde mixture of an aliphatic dialdehyde and a dialdehyde-thiophene derivative as a cross-linking agent, and cross-links and solidifies the alkali lignin through a reaction between aldehyde groups and amino groups to form a complex highly cross-linked structure, thereby reducing the generation of defects during carbonization and pyrolysis of the alkali lignin and improving the ability to inhibit the volume expansion of silicon.

[0025] In addition, by adjusting the relative amount of dialdehyde derivatives, controlling the amount of residual amino groups on the polyamine, and combining with porogens, the porous carbon material evolves from a single structure dominated by micropores to a hierarchical porous structure with coexistence of micro / mesopores, and gives the porous carbon material small and broad-peak distributed mesopores, that is, there is a half-slope platform-type mesoporous transition zone between the micropores and the macropores. This pore structure has good connectivity, and the silicon source gas can diffuse smoothly into the micropores deep inside the material, making full use of all adsorption sites, improving the dispersion uniformity of silicon particles in the porous carbon material, effectively reducing the generation of local defects, maintaining the stability of the electrode structure, and improving the cycle stability of the battery.

[0026] The present invention introduces sulfur and nitrogen elements into the porous carbon material through the grafting of polyamines and the cross-linking reaction of dialdehyde derivatives, which is beneficial to improving the conductivity of the dispersed silicon-carbon composite material, reducing the attenuation rate of the material, and extending the cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the pore size distribution diagram of the porous carbon material prepared in step 4) of Example 1;

[0028] Figure 2 This is the pore size distribution diagram of the porous carbon material prepared in step 4) of comparative example 3. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific embodiment, but is not limited to the content on the specification sheets. Unless otherwise specified, "parts" described in the embodiments of the present invention are all parts by weight. All reagents used are commercially available reagents in this area.

[0030] Black liquor from straw pulp alkaline papermaking was purchased from Beijing No. 7 Paper Mill Co., Ltd.

[0031] Example 1

[0032] 1) The pH of the straw pulp alkaline papermaking black liquor was adjusted to 7 with a 1 mol / L hydrochloric acid solution, and the filtrate was filtered and collected; then the pH was further adjusted to 2 with a 1 mol / L hydrochloric acid solution, and the mixture was stirred at 100° C. for 6 h. The filter residue was filtered and washed with water three times, and dried at 60° C. to constant weight to obtain alkali lignin.

[0033] 2) 2000 g of alkali lignin and 600 g of tetraethylenepentamine were added to 8000 mL of water, the pH was adjusted to 11 with a 1 mol / L sodium hydroxide solution, and the mixture was stirred until completely dissolved. 800 g of a 37 wt % formaldehyde solution was added under stirring and hydrothermal reaction was carried out at 80° C. for 1.5 h. After the reaction, isopropanol was added until no precipitation was produced. The mixture was filtered, washed with water until neutral, and dried at 80° C. to constant weight to obtain aminated alkali lignin;

[0034] 3) The amination-treated alkali lignin obtained in step 2) was dissolved in 8000 mL of a mixed solvent of dioxane and dichloromethane in a volume ratio of 7:3, and 300 g of a dialdehyde mixture of dodecanedial and 2,2':5',2"-terthiophene-5,5"-dicarboxaldehyde in a mass ratio of 5:10 was added. The mixture was heated and refluxed for a cross-linking reaction for 4 h. After the reaction, the mixture was filtered, washed with water three times, dried, and ground to 80 mesh to obtain a precursor;

[0035] 4) 1000 g of the precursor prepared according to method 3) was mixed evenly with 1000 g of urea, and then the mixture was heated to 500 ° C at a rate of 10 ° C / min under a nitrogen atmosphere and kept at this temperature for 1 h for carbonization. The carbonized material after carbonization was mixed evenly with a 30 wt% sodium hydroxide solution at a mass volume ratio of 1 g: 4 mL and activated in a nitrogen atmosphere. The activation procedure was to increase the temperature to 800 ° C at a rate of 10 ° C / min and keep the temperature constant for 3 h, and then naturally cooled to room temperature. The mixture was washed three times with a 1 mol / L hydrochloric acid solution, washed with water until neutral, and dried at 60 ° C to constant weight to obtain a porous carbon material with a semi-slope platform pore structure.

[0036] 5) After the chemical vapor deposition equipment was evacuated, the porous carbon material with a half-slope platform pore structure was placed in a chemical vapor deposition chamber, and a mixed gas consisting of argon and monosilane in a mass ratio of 5:95 was introduced at a flow rate of 180 mL / min for reaction. The temperature in the chemical vapor deposition chamber was 600° C., the pressure in the chemical vapor deposition chamber was 0.3 MPa, and the introduction was stopped after 1.5 hours to obtain a dispersed silicon-carbon composite material.

[0037] Example 2

[0038] The rest is the same as Example 1, except that the amount of the dialdehyde mixture used in step 3) is 480 g.

[0039] Example 3

[0040] The rest is the same as Example 1, except that the amount of the dialdehyde mixture used in step 3) is 180 g.

[0041] Example 4

[0042] The rest is the same as Example 1, except that the amount of the dialdehyde mixture used in step 3) is 540 g.

[0043] Example 5

[0044] The rest is the same as Example 1, except that in step 3), the dialdehyde mixture is prepared by mixing dodecanedial and 2,2':5',2"-terthiophene-5,5"-dicarboxaldehyde in a mass ratio of 5:7.

[0045] Example 6

[0046] The rest is the same as Example 1, except that in step 2), an equal mass of 2,2'-bithiophene-5,5'-dicarboxaldehyde is used instead of 2,2':5',2"-terthiophene-5,5"-dicarboxaldehyde.

[0047] Example 7

[0048] The rest is the same as Example 1, except that in step 2), an equal mass of triethylenetetramine is used instead of tetraethylenepentamine.

[0049] Example 8

[0050] The rest is the same as Example 1, except that the amount of tetraethylenepentamine used in step 2) is 400 g.

[0051] Example 9

[0052] The rest is the same as Example 1, except that the amount of urea used in step 4) is 2000 g.

[0053] Example 10

[0054] The rest is the same as Example 1, except that:

[0055] 2) 2000 g of alkali lignin and 600 g of tetraethylenepentamine were added to 8000 mL of water, the pH was adjusted to 11 with a 1 mol / L sodium hydroxide solution, and the mixture was stirred until completely dissolved. 800 g of a 37 wt % formaldehyde solution was added under stirring and hydrothermal reaction was carried out at 80° C. for 1.5 h. After the reaction, isopropanol was added until no precipitation was produced. The mixture was filtered, washed with water until neutral, and dried at 80° C. to constant weight to obtain aminated alkali lignin;

[0056] 3) The amination-treated alkali lignin obtained in step 2) was dissolved in 8000 mL of a mixed solvent of dioxane and dichloromethane in a volume ratio of 7:3, and 480 g of a dialdehyde derivative prepared by mixing dodecanedial and 2,2':5',2"-terthiophene-5,5"-dicarboxaldehyde in a mass ratio of 5:10 was added. The mixture was heated to reflux and subjected to a cross-linking reaction for 4 h. After the reaction, the mixture was filtered, washed with water three times, dried, and ground to 80 mesh to obtain a precursor;

[0057] 4) Take 1000 g of the precursor prepared according to method 3) and mix it evenly with 2000 g of urea. Then, under a nitrogen atmosphere, heat it to 500 ° C at a rate of 10 ° C / min and keep it at this temperature for 1 hour for carbonization. After the carbonization is completed, the carbonized material is mixed evenly with a 30 wt% sodium hydroxide solution at a mass volume ratio of 1 g: 4 mL and activated in a nitrogen atmosphere. The activation procedure is to heat it to 800 ° C at a rate of 10 ° C / min and keep it at this temperature for 3 hours. Then, it is naturally cooled to room temperature, washed with a 1 mol / L hydrochloric acid solution three times, washed with water until neutral, and dried at 60 ° C to constant weight to obtain a porous carbon material with a semi-slope platform pore structure.

[0058] 5) After the chemical vapor deposition equipment was evacuated, the porous carbon material with a half-slope platform pore structure was placed in a chemical vapor deposition chamber, and a mixed gas consisting of argon and monosilane in a mass ratio of 10:90 was introduced at a flow rate of 120 mL / min for reaction. The temperature in the chemical vapor deposition chamber was 600° C., the pressure in the chemical vapor deposition chamber was 0.2 MPa, and the introduction was stopped after 1.5 hours to obtain a dispersed silicon-carbon composite material.

[0059] Comparative Example 1

[0060] The rest is the same as Example 1, except that, in step 3), all the dialdehyde derivatives are dodecanedial.

[0061] Comparative Example 2

[0062] The rest is the same as Example 1, except that, in step 3), all the dialdehyde derivatives are 2,2':5',2"-terthiophene-5,5"-dicarboxaldehyde.

[0063] Comparative Example 3

[0064] The rest is the same as Example 1, except that in step 2), an equal mass of 1,11-diaminoundecane is used instead of tetraethylenepentamine.

[0065] Application Example 1

[0066] Prepare the battery negative electrode:

[0067] Example 1 Dispersed silicon-carbon composite material, conductive agent super P and CMC binder are composed of a mass ratio of 8:1:1. Dispersed silicon-carbon composite material, conductive agent super P and CMC binder are evenly dispersed in a solvent and coated on a 10 μm copper foil. After drying at room temperature for 4 hours, the electrode is punched into a pole piece with a punch of 14 mm in diameter and subjected to a pressure of 100 kg / cm -2 The tablets were pressed under pressure and dried in a vacuum oven at 120°C for 8 hours.

[0068] Assembling the button cell battery:

[0069] In an argon-protected glove box, based on the above-mentioned battery negative electrode, a lithium sheet was used as the counter electrode, a 1 mol / L LiPF6 solution (the volume ratio of EC, DMC, and EMC was 1:1:1) was used as the electrolyte, a celgard 2400 membrane was used as the separator, and a button cell was assembled in a CR2016 battery shell.

[0070] Application Example 2-9

[0071] The rest is the same as Application Example 1, except that the dispersed silicon-carbon composite material is prepared according to Example 2-9.

[0072] Comparative Application Examples 1-3

[0073] The rest is the same as Application Example 1, except that the dispersed silicon-carbon composite material is prepared according to Comparative Examples 1-3.

[0074] The porous carbon materials prepared in the above examples and comparative examples were subjected to pore structure performance tests; the button batteries prepared in the application examples and comparative application examples were subjected to electrochemical performance tests:

[0075] Pore ​​structure and specific surface area: measured by NOVA 1000e pore structure specific surface area tester. The sample was degassed at 350℃ for 2h and adsorbed with liquid nitrogen at 77K and relative pressure (P / P0) 10 -6 N2 adsorption was carried out in the range of -1, and the specific surface area was calculated by the BET equation.

[0076] Electrochemical performance: Constant current charge and discharge test of button cell was carried out on Wuhan Jinnuo LandCT2001A battery test system. Cyclic charge and discharge were carried out at 0.2C rate. The charge and discharge cut-off voltage was relative to Li / Li+ 0.005-2V.

[0077] Table 1 Test results

[0078]

[0079] Figure 1 This is the pore size distribution diagram of the porous carbon material prepared in Example 1 of the present invention. It can be seen that the pore size of the porous carbon material prepared in the present invention is mostly distributed in the range of about 1-10 nm, including a hierarchical structure in which small and concentrated micropores and small mesopores with a half-slope and wide-peak distribution coexist; from the electrochemical performance test results, it can be seen that the dispersed silicon-carbon composite material prepared from the carbon material with such a pore structure is suitable for the preparation of silicon-carbon negative electrode materials for lithium-ion batteries, so that the electrode structure has good stability and the battery has excellent cycle stability.

[0080] Figure 2 The pore size distribution of the porous carbon material prepared in Comparative Example 3 shows that the pore size is mainly concentrated in the range of 1-2 nm. Its microporous structure is well-developed, making it a typical microporous material. This indicates that the number of residual amino groups of the polyamine grafted on the alkali lignin plays an important role in the evolution of the porous carbon material from a single structure dominated by micropores to a hierarchical porous structure with coexistence of micro / mesopores. The performance test results of Application Example 1, Application Example 9, and Comparative Application Example 3 in Table 1 show that the amount of residual amino groups on the polyamine, combined with the porogen, enables the porous carbon material to evolve from a single structure dominated by micropores to a hierarchical porous structure with coexistence of micro / mesopores. This also gives the porous carbon material small, broad-peaked mesopores, namely, a half-slope platform-type mesoporous transition zone between micropores and macropores. This pore structure has good connectivity, allowing the silicon source gas to diffuse smoothly into the deep micropores within the material, fully utilizing all adsorption sites, improving the uniformity of silicon particle dispersion in the porous carbon material, effectively reducing the generation of local defects, maintaining the stability of the electrode structure, and improving the cycling stability of the battery.

[0081] The above detailed description is a specific description of one feasible embodiment of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not depart from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A method for preparing a porous carbon material with a semi-slope platform pore structure, characterized in that: The steps include: Alkali lignin and polyamine are added to water, the pH is adjusted, and the mixture is stirred until completely dissolved. Formaldehyde solution is added under stirring to carry out a hydrothermal reaction. After the reaction is completed, isopropanol is added until no precipitation is produced. The mixture is filtered, washed, and dried to obtain aminated alkali lignin. 2) dissolving the amination alkali lignin in an organic solvent, adding a dialdehyde mixture, heating to reflux to carry out a cross-linking reaction, filtering, washing, drying, and grinding after the reaction to obtain a precursor; 3) The precursor and the porogen are mixed evenly, and then carbonized under an inert atmosphere. The carbonized material is then mixed with an alkaline solution and activated in an inert atmosphere. The material is cooled, pickled, washed with water, and dried to obtain a porous carbon material with a semi-slope platform pore structure. Step 1) the polyamine is selected from one or a combination of two or more of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; the mass ratio of the alkali lignin, polyamine, and formaldehyde solution is 15-20:4-6:5-8; The dialdehyde mixture in step 2) is a mixture of aliphatic dialdehyde and dialdehyde-thiophene derivative in a mass ratio of 5:7-10; the mass ratio of the dialdehyde mixture in step 2) to the polyamine in step 1) is 0.5-0.8:

1.

2. The method for preparing the porous carbon material with a half-slope platform pore structure according to claim 1, characterized in that: Step 1) The polyamine is tetraethylenepentamine.

3. The method for preparing the porous carbon material with a half-slope platform pore structure according to claim 1, characterized in that: Step 2) The aliphatic dialdehyde is a C8-C12 aliphatic dialdehyde, selected from one or a combination of two or more of heptanedialdehyde, octanedial, nonanedialdehyde, and dodecanedial; the aldehyde thiophene derivative is selected from one or a combination of two or more of 3,4-thiophene dicarboxaldehyde, 2,3-thiophene dicarboxaldehyde, 2,2'-bithiophene-5,5'-dicarboxaldehyde, and 2,2':5',2''-terthiophene-5,5''-dicarboxaldehyde.

4. The method for preparing the porous carbon material with a half-slope platform pore structure according to claim 3, characterized in that: Step 2) The aliphatic dialdehyde is dodecanedial.

5. The method for preparing the porous carbon material with a half-slope platform pore structure according to claim 3, characterized in that: In step 2), the aldehyde thiophene derivative is 2,2':5',2''-terthiophene-5,5''-dicarboxaldehyde.

6. The method for preparing the porous carbon material with a half-slope platform pore structure according to claim 1, characterized in that: The pH is adjusted to 10-11 using an alkali solution with a concentration of 0.5-1 mol / L; the hydrothermal reaction temperature is 40-80° C., and the hydrothermal reaction time is 1-3 hours; and the washing is performed with water until the pH is neutral.

7. The method for preparing the porous carbon material with a half-slope platform pore structure according to claim 1, characterized in that: The cross-linking reaction time is 4-6 hours; the organic solvent is selected from one or a combination of two or more of chloroform, pyridine, dichloromethane, ethanol, acetone, dioxane, and ethyl acetate.

8. The method for preparing the porous carbon material with a half-slope platform pore structure according to claim 7, characterized in that: The organic solvent is a mixed solvent of dioxane and dichloromethane in a volume ratio of 7:2-4.

9. The method for preparing the porous carbon material with a half-slope platform pore structure according to claim 8, characterized in that: The organic solvent is a mixed solvent of dioxane and dichloromethane in a volume ratio of 7:

3.

10. The method for preparing the porous carbon material with a half-slope platform pore structure according to claim 1, characterized in that: Step 3) The mass ratio of the precursor to the porogen is 1:1-2; the porogen is selected from one or a combination of two or more of ammonium carbonate, urea, ammonium bicarbonate, ammonium formate, ammonium acetate, and ammonium oxalate.

11. A porous carbon material with a half-slope platform pore structure prepared by the method for preparing a porous carbon material with a half-slope platform pore structure according to any one of claims 1 to 10.

12. A method for preparing a dispersed silicon-carbon composite material, characterized in that: After evacuating the chemical vapor deposition equipment, the porous carbon material with a half-slope platform type pore structure prepared by the preparation method of the porous carbon material with a half-slope platform type pore structure according to any one of claims 1 to 10 or the porous carbon material with a half-slope platform type pore structure according to claim 11 is placed in a chemical vapor deposition chamber, and silicon source gas is introduced to perform vapor deposition of silicon to obtain a dispersed silicon-carbon composite material.

13. The method for preparing the dispersed silicon-carbon composite material according to claim 12, characterized in that: The temperature in the chemical vapor deposition chamber is 500-600°C, the pressure in the chemical vapor deposition chamber is 0.1-0.3MPa, the silicon source gas and the inert gas are mixed in a volume ratio of 5-10:90-95, the mixed gas is introduced for 1-4h, and the mixed gas flow rate is 120-180mL / min; the silicon source gas is selected from one or a combination of monosilane and disilane.

14. A lithium ion battery, characterized in that: The lithium-ion battery includes a negative electrode, and the negative electrode includes the dispersed silicon-carbon composite material prepared by the preparation method of the dispersed silicon-carbon composite material according to claim 12 or claim 13.

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