A method for preparing a carbon composite material doped with multiple metal elements

Abstract

The application discloses a preparation method of a carbon composite material doped with multiple metal elements. The preparation process comprises the following steps: S1, dispersing a porous carbon precursor, organic lithium fluoride, an organic rare earth compound and an organic catalyst in a solvent, drying after hydrothermal reaction, and obtaining the porous carbon precursor loaded with lithium / rare earth elements / catalysts; S2, uniformly mixing the obtained material with an activating agent and a doping agent, and activating at a temperature of 900-1100 DEG C to obtain the porous carbon doped with multiple metal elements; and S3, performing reduction treatment and surface passivation treatment on the porous carbon doped with multiple metal elements to obtain the porous carbon composite material doped with multiple metal elements. The obtained material utilizes lithium doping and rare earth doping porous carbon to improve the electronic conductivity of the material and the interlayer spacing of the carbon material, utilizes the catalyst to grow carbon nanotubes to improve the conductivity of the material and reduce the expansion, and through reduction and passivation treatment, the activity of the surface of the material is reduced, and the initial efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation, specifically a method for preparing carbon composite materials doped with multiple metal elements. Background Technology

[0002] Porous carbon, as one of the raw materials for preparing silicon-carbon materials, possesses a large specific surface area and abundant pores, allowing it to accommodate more active substances. However, the poor electronic conductivity and numerous pores of porous carbon itself reduce its compressive strength. Therefore, it is necessary to modify it to improve the electronic or ionic conductivity of the material, thereby enhancing its compressive strength and ensuring the stability of the material structure during cycling, thus improving cycling performance. Existing technologies mainly improve the electronic conductivity of the material by doping it with non-metallic atoms or gold, but they do not improve the ionic conductivity or initial efficiency. Summary of the Invention

[0003] To improve the conductivity of porous carbon, reduce surface defects, and enhance first-pass efficiency and rate performance, this invention employs multi-metal doping and increases the interlayer spacing and orientation of carbon materials to improve the electronic conductivity of porous carbon itself, reduce surface defects, and enhance rate performance and first-pass efficiency.

[0004] A method for preparing a carbon composite material doped with multiple metal elements, characterized by comprising the following steps:

[0005] Step S1:

[0006] A porous carbon precursor, lithium organofluoride, organic rare earth compound, and organic catalyst were added to methanol solvent at a mass ratio of 100:1-5:1-5:1-5 to prepare a solution with a mass concentration of 5-30 wt%. The solution was then transferred to a high-pressure reactor and subjected to hydrothermal reaction at a temperature of 100℃-200℃ and a pressure of 0.11-0.5 MPa for 1-6 hours. After filtration, the filter residue was vacuum dried at 80℃ for 24 hours to obtain a porous carbon precursor supported on lithium / rare earth elements / catalyst.

[0007] Step S2:

[0008] Porous carbon precursor, activator and dopant are mixed evenly at a mass ratio of 100:100-500:10-30 and activated at 900℃-1100℃ for 1-6 hours to obtain porous carbon doped with multi-metal elements.

[0009] Step S3:

[0010] Porous carbon doped with multiple metal elements is transferred to a tube furnace, heated to 650℃-800℃, and carbon monoxide or hydrogen reducing gas is introduced at a flow rate of 100-500 ml / min for 60-600 min. The obtained material is then cooled to 500-600℃, and a fluoroalkane gas / carbon source mixed gas is introduced at a flow rate of 100-500 ml / min for deposition for 30-300 min, to obtain a carbon composite material doped with multiple metal elements.

[0011] In step S1, the porous carbon precursor is one of glucose, sucrose, maltose, lactose, fructose, cellulose, and starch; the organofluorine lithium is one of lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium perfluorohexanesulfonate, lithium perfluorobutylsulfonate, lithium difluorooxalate borate, lithium difluoroacetate, and lithium difluorodioxalate phosphate; the organic rare earth compound is one of lanthanum acetate, lanthanum stearate, lanthanum acetate, cerium oxalate, neodymium oxalate, and neodymium oxalate; and the organic catalyst is one of ferrocene, cobalt acetylacetonate, stannous octoate, bismuth octoate, lithium isooctanoate, and nickel isooctanoate.

[0012] In step S2, the activator is one of potassium hydroxide, sodium hydroxide, magnesium hydroxide, potassium carbonate, potassium bicarbonate, and lithium hydroxide; the dopant is one of pyridine, 2-mercaptopyridine, 3-pyridineboronic acid, pyridineboron, and methylpyridinephosphine.

[0013] In step S3, the fluoroalkane gas is one of tetrafluoromethane, nitrogen trifluoride, vinylidene fluoride, tetrafluoroethylene, trifluorochloroethylene, and perfluorocyclobutane; the carbon source gas is one of methane, ethane, ethylene, acetylene, and propyne; the volume ratio of fluoroalkane gas to carbon source gas is 1:0.5-2.

[0014] Beneficial effects

[0015] 1. By adding organofluorine oxide, organoravenous earth compounds, and organic catalysts to a porous carbon precursor and reacting under high pressure, lithium and rare earth elements are doped into the porous carbon precursor. Lithium doping reduces defects on the surface of the carbon material, while rare earth doping improves electronic conductivity. Furthermore, rare earth elements promote the orientation and arrangement of carbon during sintering, forming anisotropic carbon materials and improving the electronic conductivity of the porous carbon itself. The organic catalyst, doped into the porous carbon precursor, can expand the interlayer spacing of carbon during heating, increasing the ion insertion / extraction rate during use. In the subsequent high-temperature sintering process, the catalyst reacts with the carbon source gas to grow carbon nanotubes, further improving electronic conductivity and reducing expansion. This invention uses organofluorine oxide, organoravenous earth compounds, and organic catalysts, with mild reaction conditions, high reaction efficiency, and few residual impurities after the reaction, leaving a porous structure, which is beneficial for the formation of porous carbon.

[0016] 2. By introducing a mixed gas of fluoroalkane gas and carbon source, the surface of porous carbon is modified, reducing the surface defects of the porous carbon material. Furthermore, the fluorine-doped amorphous carbon obtained after carbonization with fluoroalkane gas has high electronic conductivity and can reduce the defects of porous carbon itself, thereby improving the first-pass efficiency of porous carbon. Attached Figure Description

[0017] Figure 1 The image shows a SEM image of the porous carbon prepared in Example 1. Detailed Implementation

[0018] Example 1

[0019] A method for preparing a carbon composite material doped with multiple metal elements includes the following steps:

[0020] Step S1:

[0021] 100g of glucose, 3g of lithium tetrafluoroborate, 3g of lanthanum acetate, and 3g of ferrocene were added to 981g of methanol solvent to prepare a 10wt% solution. The solution was then transferred to a high-pressure reactor and subjected to hydrothermal reaction at 150℃ and 0.3MPa for 3 hours. After filtration, the filter residue was vacuum dried at 80℃ for 24 hours to obtain a porous carbon precursor supported on lithium / rare earth elements / catalyst.

[0022] Step S2:

[0023] 100g of porous carbon precursor was mixed with 300g of potassium hydroxide activator and 20g of pyridine, and activated at 1000℃ for 3h to obtain multi-metal element doped porous carbon.

[0024] Step S3:

[0025] The porous carbon doped with multi-metal elements was transferred to a tube furnace, heated to 750°C, and carbon monoxide gas was introduced at a flow rate of 300 ml / min for 300 min. The obtained material was then cooled to 550°C, and a tetrafluoromethane / ethylene gas mixture was introduced at a flow rate of 300 ml / min with a tetrafluoromethane:ethylene volume ratio of 1:1 for 150 min to obtain a porous carbon composite material doped with multi-metal elements.

[0026] Example 2

[0027] A method for preparing a porous carbon composite material containing multiple metal elements includes the following steps:

[0028] Step S1:

[0029] 100g of sucrose, 1g of lithium trifluoromethanesulfonate, 1g of lanthanum stearate, and 1g of cobalt acetylacetonate were added to 1957g of methanol solvent to prepare a 5wt% solution. The solution was then transferred to a high-pressure reactor and subjected to hydrothermal reaction at 100℃ and 0.5MPa for 6 hours. After filtration, the filter residue was vacuum dried at 80℃ for 24 hours to obtain a porous carbon precursor supported on lithium / rare earth elements / catalyst.

[0030] Step S2:

[0031] 100g of porous carbon precursor was mixed with 100g of sodium hydroxide and 10g of 2-mercaptopyridine and activated at 900℃ for 6h to obtain multi-metal element doped porous carbon.

[0032] Step S3:

[0033] The porous carbon doped with multi-metal elements was transferred to a tube furnace, heated to 650°C, and hydrogen was introduced at a flow rate of 100 ml / min for 600 min. The obtained material was then cooled to 500°C, and a mixture of nitrogen trifluoride and acetylene gas was introduced at a flow rate of 100 ml / min for deposition for 300 min, with a nitrogen trifluoride:acetylene volume ratio of 1:0.5, to obtain a porous carbon composite material doped with multi-metal elements.

[0034] Example 3

[0035] A method for preparing a porous carbon composite material containing multiple metal elements includes the following steps:

[0036] Step S1:

[0037] 100g of maltose, 5g of lithium perfluorohexanesulfonate, 5g of lanthanum acetate, and 5g of stannous octoate were added to 268.3g of methanol solvent to prepare a solution with a mass concentration of 30wt%. The solution was then transferred to a high-pressure reactor and subjected to hydrothermal reaction at 200℃ and 0.11MPa for 1h. After filtration, the filter residue was vacuum dried at 80℃ for 24h to obtain a porous carbon precursor supported on lithium / rare earth elements / catalyst.

[0038] Step S2:

[0039] 100g of porous carbon precursor was mixed with 500g of magnesium hydroxide and 30g of 3-pyridineboronic acid, and activated at 1100℃ for 1h to obtain multi-metal element doped porous carbon.

[0040] Step S3:

[0041] The porous carbon doped with multi-metal elements was transferred to a tube furnace, heated to 800°C, and carbon monoxide was introduced at a flow rate of 500 ml / min for 60 min. The obtained material was then cooled to 600°C, and a mixture of vinylidene fluoride gas and methane gas was introduced at a flow rate of 500 ml / min for deposition at a volume ratio of 1:2 for 30 min, to obtain a porous carbon composite material doped with multi-metal elements.

[0042] Comparative Example 1:

[0043] Unlike Example 1, lithium tetrafluoroborate is not added in step S1; otherwise, it is the same as in Example 1. The detailed process is as follows: 100g of glucose, 3g of lanthanum acetate, and 3g of ferrocene are added to 954g of methanol solvent to prepare a solution with a mass concentration of 10wt%, otherwise, it is the same as in Example 1.

[0044] Comparative Example 2:

[0045] Unlike Example 1, lanthanum acetate is not added in step S1, but everything else is the same as in Example 1.

[0046] Comparative Example 3:

[0047] Unlike Example 1, tetrafluoromethane gas is not introduced in step S3; otherwise, the process is the same as in Example 1.

[0048] Performance testing

[0049] 1. Scanning electron microscopy (SEM) test:

[0050] SEM images of the porous carbon composite material with multiple metal elements prepared in Example 1 were obtained. Figure 1 As can be seen, the material exhibits a spherical structure with a uniform size distribution and a particle size between 5 and 10 μm.

[0051] 2. Physicochemical and button cell tests:

[0052] 2.1 Physicochemical property testing:

[0053] The pore volume and pore size of the porous carbon composite materials obtained in Examples 1-3 and Comparative Examples 1-3 were tested according to the national standard GB / T-38949-2020 "Determination of Pore Size of Porous Membranes - Standard Particle Method".

[0054] The particle size, tap density, specific surface area, and tap density of the porous carbon materials were tested according to the national standard GB / T38823-2020 "Silicon Carbon". The electrical conductivity of each porous carbon material was tested using a four-probe tester, and the diffusion coefficient of the materials was tested using GITT. At the same time, a 5T pressure was applied to test the specific surface area to determine the degree of particle breakage.

[0055] The test results are shown in Table 1.

[0056] 2.2 Button Cell Battery Performance Test:

[0057] The porous carbon composite materials with multiple metal elements corresponding to Examples 1-3 and Comparative Examples 1-3 were used as negative electrode materials for lithium-ion batteries to prepare coin cells according to the following method:

[0058] A binder, conductive agent, and solvent were added to a porous carbon composite material containing various corresponding multi-metal elements, and the mixture was stirred to form a slurry. The slurry was then coated onto a copper foil, dried, and rolled to obtain a negative electrode sheet. The binder used was LA132, the conductive agent was SP (conductive carbon black), and the solvent was NMP. The ratio of the multi-metal porous carbon composite material SP:LA132:NMP was 70g:15g:15g:300mL. The electrolyte was a solution with LiPF6 as the electrolyte and a concentration of 1mol / L. The solvent was a mixture of EC and DEC with a volume ratio of 1:1. The lithium metal sheet was used as the counter electrode, and the separator was a polypropylene (PP) membrane.

[0059] Each coin cell was assembled in an argon-filled glove box, and then the following performance tests were performed: Electrochemical performance test: Specifically, the electrochemical performance was performed on a Wuhan Landian CT2001A battery tester, with a charge / discharge voltage range of 0.005V to 1.5V and a charge / discharge rate of 0.1C. The discharge specific capacity and initial efficiency of the corresponding coin cell were tested. At the same time, the room temperature charge DCR (50% SOC) and cycle performance (0.1C / 0.1C, 100 cycles) of the corresponding coin cell were tested; and the full charge expansion of the negative electrode was also tested.

[0060] The test results are shown in Table 2.

[0061]

[0062] As can be seen from Table 1, the doping of lithium and rare earth elements in the materials of the examples improves the electronic conductivity of the materials. Furthermore, the carbonization of organic lithium compounds and organic rare earth compounds also leaves pores, which increases the specific surface area of ​​the materials. In addition, the porous carbon containing metal formed after carbonization improves the particle strength of the materials, making its specific surface area change less under pressure.

[0063]

[0064] As can be seen from Table 2, Examples 1-3 have excellent diffusion coefficients and high first-pass efficiency. This is because the lithium doping in the materials of these examples reduces defects, increases the ion diffusion rate of the materials, and reduces defects, thereby improving the first-pass efficiency and rate performance. At the same time, the outer layer is coated with heteroatom amorphous carbon, which improves the electronic conductivity of the materials and reduces DCR.

[0065] The applicant declares that the present invention is illustrated by the above embodiments, 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 improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a carbon composite material doped with multiple metal elements, characterized in that, Includes the following steps: Step S1: A porous carbon precursor, lithium organofluoride, organic rare earth compound, and organic catalyst were added to methanol solvent at a mass ratio of 100:1-5:1-5:1-5 to prepare a solution with a mass concentration of 5-30 wt%. The solution was then transferred to a high-pressure reactor and hydrothermally reacted at a temperature of 100℃-200℃ and a pressure of 0.11-0.5 MPa for 1-6 hours. After filtration, the filter residue was vacuum dried at 80℃ for 24 hours to obtain a porous carbon precursor supported on lithium / rare earth elements / catalyst. Step S2: Porous carbon precursor, activator and dopant are mixed evenly at a mass ratio of 100:100-500:10-30 and activated at 900℃-1100℃ for 1-6 hours to obtain porous carbon doped with multi-metal elements. Step S3: Porous carbon doped with multiple metal elements is transferred to a tube furnace, heated to 650℃-800℃, and carbon monoxide or hydrogen reducing gas is introduced at a flow rate of 100-500 ml / min for 100-600 min. The obtained material is then cooled to 500℃-600℃, and a mixture of fluoroalkane gas and carbon source gas is introduced at a flow rate of 100-500 ml / min for 30-300 min for deposition, thus obtaining a carbon composite material doped with multiple metal elements.

2. The method for preparing a carbon composite material doped with multiple metal elements according to claim 1, characterized in that, In step S1, the porous carbon precursor is one of glucose, sucrose, maltose, lactose, fructose, cellulose, and starch; the organofluorine lithium is one of lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium perfluorohexanesulfonate, lithium perfluorobutylsulfonate, lithium difluorooxalate borate, lithium difluoroacetate, and lithium difluorodioxalate phosphate; the organic rare earth compound is one of lanthanum stearate, lanthanum acetate, cerium oxalate, and neodymium oxalate; and the organic catalyst is one of ferrocene, cobalt acetylacetonate, stannous octoate, bismuth octoate, lithium isooctanoate, and nickel isooctanoate.

3. The method for preparing carbon composite materials doped with multiple metal elements according to claim 1, characterized in that, In step S2, the activator is one of potassium hydroxide, sodium hydroxide, magnesium hydroxide, potassium carbonate, potassium bicarbonate, and lithium hydroxide; the dopant is one of pyridine, 2-mercaptopyridine, 3-pyridineboronic acid, pyridineboron, and methylpyridinephosphine.

4. The method for preparing carbon composite materials doped with multiple metal elements according to claim 1, characterized in that, In step S3, the fluoroalkane gas is one of tetrafluoromethane, vinylidene fluoride, tetrafluoroethylene, trifluorochloroethylene, or perfluorocyclobutane; the carbon source gas is one of methane, ethane, ethylene, acetylene, or propyne; the volume ratio of fluoroalkane gas to carbon source gas is 1:0.5-2.

Images