Mesoporous carbon composite material and preparation method thereof

Abstract

The invention discloses a mesoporous carbon composite material and a preparation method thereof.The preparation method comprises the steps that S1, tetraethyl orthosilicate serves as a silicon source, an ethyl alcohol / deionized water mixed solution and a surfactant serve as a solvent system, a conductive agent serves as a doping agent, condensation polymerization is carried out under an acid-base catalyst, a silicon dioxide / soft template compound is formed through the sol-gel process, and the mesoporous carbon composite material is obtained; sintering at high temperature to obtain a silicon dioxide composite template; s2, mixing a phenol source, a dispersing agent and water to prepare a mixed solution A; mixing an aldehyde source, a lithium supplement agent and a catalyst to prepare a mixed solution B; s3, mixing the mixed solution A, the mixed solution B and the silicon dioxide composite template for reaction, carbonizing and activating, then adding the obtained material into a hydrofluoric acid solution to dissolve the template, and performing thermal reduction on the obtained material to obtain the mesoporous carbon composite material. Mesoporous carbon prepared from the obtained material by using a template method has the advantages of high consistency, large pore volume, low powder resistivity and the like, and is applied to a silicon-carbon composite material to improve the deposition amount of nano silicon, improve the specific capacity and reduce the expansion of the silicon-carbon material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of material preparation, and particularly relates to a mesoporous carbon composite material and a preparation method thereof. BACKGROUND

[0002] As a high-energy-density negative electrode material, the expansion of silicon-carbon material and its power performance have a great influence on the expansion and cycle of the battery in the application process. The porous carbon used in the current silicon-carbon material is prepared by pre-carbonization and activation of resin or biomass, and has small pore size, small pore volume and poor consistency, which causes large expansion of the material. Mesoporous carbon has the advantages of large pore size, high pore volume, few defects and good consistency, which reduces the expansion of nano-silicon in the charging and discharging process. At present, mesoporous carbon is mainly prepared by a template method. For example, patent application No. CN201811021947.5 discloses a method for preparing high specific surface area macroporous-mesoporous carbon using a salt template and application thereof, and the preparation method is as follows: biomaterial gelatin is dissolved in hot water to form a sol, an inorganic salt is added as a template agent to prepare a aerogel, and the obtained aerogel is sintered at high temperature. The carbon material prepared by the method of the patent has poor power performance and many defects, which causes low initial efficiency. SUMMARY

[0003] In order to improve the power performance and initial efficiency of mesoporous carbon, the present application prepares a conductive agent doped silica template, and deposits lithium doped phenolic resin on the surface of mesoporous carbon, activates and removes the template to obtain a conductive agent / lithium doped mesoporous carbon, so as to improve the power and initial efficiency of mesoporous carbon.

[0004] A preparation method of a mesoporous carbon composite material, characterized in that the method comprises the following steps: Step S1: A tetraethyl orthosilicate: ethanol / deionized water mixture: surfactant: dopant are weighed according to a mass ratio of 100:200-300:0.5-2:1-5, the surfactant is dissolved in deionized water to prepare a solution with a mass concentration of 0.5-2wt%, then the tetraethyl orthosilicate, the ethanol / deionized water mixture and the dopant are mixed uniformly, 0.1mol / L hydrochloric acid is added for hydrolysis, then 0.1mol / L ammonia water is added dropwise to adjust the pH to 6-8, a polycondensation reaction is performed, filtration is performed, and high-temperature sintering is performed at 800-1100°C for 1-3h to obtain a silica template; Step S2: A phenol source: dispersant: water are mixed according to a mass ratio of 100:1-5:500-1000 to prepare a mixed solution A; An aldehyde source: lithium supplement: catalyst: water are weighed according to a mass ratio of 100:1-5:1-5:500-1500, the aldehyde source, the lithium supplement and the catalyst are added to deionized water for mixing to prepare a mixed solution B; Step S3: Mixed solution A, mixed solution B, and silica template were prepared at a mass ratio of 1000:500-1000:10-30. Mixed solution A and mixed solution B were then added, and the mixture was stirred until homogeneous. The mixture was reacted at 80℃-150℃ for 1-6 hours. The resulting material was filtered and carbonized at 700℃-900℃ for 1-6 hours. Then, the temperature was raised to 950℃-1100℃, and steam was introduced at a flow rate of 50-200 ml / min for activation for 60-600 minutes. The resulting material was then added to hydrofluoric acid solution to dissolve the silica template. Finally, the resulting material was thermally reduced at 400℃-600℃ under an inert atmosphere for 1-3 hours to obtain a mesoporous carbon composite material.

[0005] In step S1, the surfactant is one of sodium dodecylbenzenesulfonate, lauryl alcohol chloride, sodium benzoate, and sulfonamide chloride; the dopant is one of graphene, carbon nanotubes, and fumed carbon fibers.

[0006] In step S2, the phenol source is one of phenol, cresol, catechol, or hydroquinone; the dispersant is one of polyvinyl alcohol, polypyrrolidone, polyethylene glycol, sodium dodecyl sulfonate, sodium dodecyl sulfate, hexadecyl ammonium bromide, or polyoxyethylene-polyoxypropylene-polyoxyethylene (F127); the aldehyde source is one of formaldehyde, acetaldehyde, acetone aldehyde, glyoxal, or furfural; the lithium supplement is one of lithium-rich lithium iron phosphate, lithium-rich lithium nickel phosphate, lithium-rich lithium cobalt phosphate, or lithium-rich lithium manganese phosphate; and the catalyst is one of sodium hydroxide, barium hydroxide, ammonia, or ammonium chloride.

[0007] Mesoporous carbon composite materials have parameters such as pore size of 5-30 nm and specific surface area of ​​1000-1500 m². 2 / g, pore volume 1-1.4cm 3 / g. Beneficial effects

[0008] 1. A conductive agent-doped silica template is prepared by polycondensation reaction, which has good uniformity. The pores left after removing the template contain conductive agents, thus reducing impedance. This invention improves the dispersion performance of the material by adding surfactants, enhances conductivity by adding dopants, and then further enhances conductivity by forming a silica template. 2. Simultaneously adding a lithium supplement to the phenolic mixture and pre-dispersing the lithium supplement in the aldehyde compound before the phenolic reaction allows the lithium compound to be doped into the phenolic compound material, resulting in lithium-doped phenolic resin. After activation, lithium-doped mesoporous carbon is obtained, which improves the ionic conductivity of the material. 3. The obtained mesoporous carbon contains conductive agents in its core pores and lithium in its shell. It leverages the electronic conductivity of the core conductive agent and the ionic conductivity of the lithium compound in its shell to improve the electronic and ionic conductivity of the material, thereby improving rate performance, reducing defects, and increasing initial efficiency. Attached Figure Description

[0009] Figure 1 The image shows a SEM image of the mesoporous carbon composite material prepared in Example 1. Detailed Implementation

[0010] Example 1 A method for preparing a mesoporous carbon composite material includes the following steps: Step S1: 1g of sodium benzoate was dissolved in 99g of deionized water to prepare a 1wt% solution. Then, 100g of tetraethyl orthosilicate, 150g of ethanol / deionized water mixture (ethanol:deionized water volume ratio = 1:1), and 3g of graphene were added and mixed evenly. Then, 500ml of 0.1mol / L hydrochloric acid was added to hydrolyze the solution. Then, 500ml of 0.1mol / L ammonia was added dropwise to adjust the pH to 7 and the polycondensation reaction was carried out for 1 hour. The filtered material was sintered at 900℃ for 2 hours to obtain a silica template. Step S2: Mix 100g of phenol, 3g of polyvinyl alcohol and 800g of water to prepare mixed solution A; Mix 100g formaldehyde, 3g lithium iron ferrite, and 3g sodium hydroxide in 800g deionized water to prepare mixed solution B. Step S3: 1000g of mixed solution A and 800g of mixed solution B were mixed evenly, and 20g of silica template was added and mixed evenly. The mixture was reacted at 90℃ for 3h, filtered, and the resulting material was carbonized at 800℃ for 3h. Then, the temperature was raised to 1000℃ and steam was introduced at a flow rate of 100ml / min for activation for 300min. The resulting material was then added to 500ml of hydrofluoric acid solution to dissolve the silica template. The filter residue was sintered at 500℃ under a nitrogen inert atmosphere for 2h to obtain a mesoporous carbon composite material.

[0011] Example 2

[0012] A method for preparing a mesoporous carbon composite material includes the following steps: Step S1: 0.5 g of sodium dodecylbenzenesulfonate was dissolved in 99.5 g of deionized water to prepare a solution with a mass concentration of 0.5 wt%. Then, 100 g of tetraethyl orthosilicate, 200 g of ethanol / deionized water mixture (ethanol:deionized water volume ratio = 1:1), and 1 g of carbon nanotubes were added and mixed evenly. Then, 500 g of 0.1 mol / L hydrochloric acid was added to hydrolyze the solution. Then, 500 g of 0.1 mol / L ammonia was added dropwise to adjust the pH to 7 and the polycondensation reaction was carried out for 1 h. The filter residue was sintered at 800℃ for 3 h to obtain a silica template. Step S2: Mix 100g of cresol, 1g of polypyrrolidone and 500ml of water to prepare mixed solution A; Add 100g of acetaldehyde, 1g of lithium-rich nickel oxide, and 1g of barium hydroxide to 500g of deionized water and mix to prepare mixed solution B. Step S3: 1000g of mixed solution A and 500g of mixed solution B were mixed, and 10g of silica template was added and mixed evenly. The mixture was reacted at 80℃ for 6h. The resulting filter residue was carbonized at 700℃ for 6h. Then, the temperature was raised to 950℃ and steam was introduced at a flow rate of 200ml / min for activation for 600min. The resulting material was then added to 500g of hydrofluoric acid solution to dissolve the silica template. The resulting filter residue was then thermally reduced and sintered at 400℃ under a nitrogen inert atmosphere for 3h to obtain a mesoporous carbon composite material.

[0013] Example 3

[0014] A method for preparing a mesoporous carbon composite material includes the following steps: Step S1: 2g of lauryl alcohol chloride was dissolved in 98g of deionized water to prepare a 2wt% solution. Then, 100g of tetraethyl orthosilicate, 300g of ethanol / deionized water mixture (ethanol:deionized water volume ratio = 1:1), and 5g of fumed carbon fiber were added and mixed evenly. Then, 500ml of 0.1mol / L hydrochloric acid was added to hydrolyze the solution. Then, 500ml of 0.1mol / L ammonia was added dropwise to adjust the pH to 7 and the polycondensation reaction was carried out for 1 hour. The filter residue was sintered at 1100℃ for 1 hour to obtain a silica template. Step S2: Mix 100g of catechol, 5g of polyethylene glycol and 1000g of water to prepare mixed solution A; Add 100g of acetone aldehyde, 5g of lithium cobalt oxide, and 5g of ammonium chloride to 1500g of deionized water and mix to prepare mixed solution B. Step S3: Mix 1000g of mixed solution A and 1500g of mixed solution B, add 30g of silica template and mix evenly, react at 150℃ for 1h, filter, and carbonize the resulting filter residue at 900℃ for 1h. Then, raise the temperature to 1100℃ and pass steam at a flow rate of 200ml / min for activation for 60min. Then, add the resulting material to 500ml of hydrofluoric acid solution to dissolve the silica template. Finally, perform thermal reduction sintering at 600℃ under a nitrogen inert atmosphere for 1h to obtain a mesoporous carbon composite material.

[0015] Comparative Example 1: Unlike Example 1, step S3 does not involve adding a silica template; otherwise, it is the same as Example 1.

[0016] The detailed preparation process is as follows: 100g of phenol, 3g of polyvinyl alcohol and 800g of water are mixed to prepare mixed solution A; 100g of formaldehyde, 3g of lithium iron ferrite and 3g of sodium hydroxide are added to 800g of deionized water and mixed to prepare mixed solution B; then 1000g of mixed solution A and 800g of mixed solution B are mixed evenly and reacted at 90℃ for 3h, filtered, and the resulting material is carbonized at 800℃ for 3h, then heated to 1000℃ and activated by passing water vapor at a flow rate of 100ml / min for 300min, and then sintered at 500℃ under a nitrogen inert atmosphere for 2h to obtain mesoporous carbon composite material.

[0017] Comparative Example 2: Unlike Example 1, step S2 does not involve the addition of lithium-rich lithium iron phosphate; otherwise, it is the same as Example 1.

[0018] I. Scanning electron microscope image

[0019] The mesoporous carbon composite material prepared in Example 1 was tested by scanning electron microscopy (SEM), and the results are as follows: Figure 1 As shown, by Figure 1 It can be seen that the obtained composite material exhibits a perfect spherical structure with a particle size between 5-10 μm and a uniform size distribution.

[0020] II. Physicochemical and Button Cell Testing

[0021] The physicochemical properties of the mesoporous carbon composite materials prepared in each embodiment and comparative example were tested: the pore size and specific surface area of ​​each porous carbon were tested according to the national standards GB / T-38949-2020 "Determination of Pore Size of Porous Membranes - Standard Particle Method" and GB / T7702.20-2008 "Detection of Pore Volume of Coal-based Activated Carbon"; and the resistivity of each porous carbon powder was tested using a four-probe tester. The test results are shown in Table 1.

[0022]

[0023] As can be seen from Table 1, the mesoporous carbon composite materials prepared by each embodiment are superior to the comparative example in terms of pore size, pore volume, specific surface area and powder resistivity. The reason is that the embodiments improve the pore size and pore volume of the material by using a silica template. At the same time, the doping of lithium supplements reduces defects, improves ionic conductivity and reduces powder resistivity.

[0024] Coin cells were prepared as follows: A negative electrode active material, binder, conductive agent, and solvent were mixed (in a ratio of 70g:15g:15g:300mL), stirred to form a slurry, and then coated onto copper foil. After drying and pressing, a negative electrode sheet was obtained. The binder used was LA136D, the conductive agent was SP (conductive carbon black), and the solvent was NMP. The electrolyte was a LiPF6 solution with a concentration of 1mol / L, and the solvent was a mixture of EC and DEC in a 1:1 volume ratio. A lithium metal sheet was used as the counter electrode, and a polypropylene (PP) membrane was used as the separator. Each coin cell was assembled in an argon-filled glove box.

[0025] Then, the following performance tests were performed on each button cell: (1) Electrochemical performance was tested on the Wuhan Landian CT2001A battery tester. The charge and discharge voltage range was 0.005V to 1.5V, and the charge and discharge rate was 0.1C. The discharge specific capacity and initial efficiency of the corresponding coin cell were tested. At the same time, the cycle performance (0.1C / 0.1C, 100 cycles) of the corresponding coin cell was tested.

[0026] (2) Full charge expansion test: Test the thickness D1 of the electrode after rolling, and test the thickness D2 when fully charged to 100% SOC. Full charge expansion = (D2-D1) / D1.

[0027] (3) The lithium-ion diffusion coefficient of the material was tested by GITT. The test results are shown in Table 2.

[0028]

[0029] As shown in Table 2, compared with the comparative examples, the mesoporous carbon composite materials prepared in each example have high specific capacity, first-pass efficiency and diffusion coefficient. The reason is that in the preparation process of each example, lithium supplementation agent is doped to reduce defects and increase the diffusion rate of lithium ions, thereby improving the first-pass efficiency and rate performance. At the same time, porous carbon with larger pore size and pore volume is prepared by using silica template, which reduces expansion and improves cycle performance.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing a mesoporous carbon composite material, characterized by, Comprising the following steps: Step S1: The tetraethyl orthosilicate: ethanol / deionized water mixture:surfactant:dopant is weighed according to the mass ratio = 100:200-300:0.5-2:1-5, the surfactant is dissolved in deionized water to prepare a solution with a mass concentration of 0.5-2wt%, then the tetraethyl orthosilicate, ethanol / deionized water mixture, and dopant are mixed uniformly, then 0.1mol / L hydrochloric acid is added for hydrolysis, then 0.1mol / L ammonia water is added to adjust the PH to 6-8, and then the polycondensation reaction is carried out, filtration, high temperature sintering at 800-1100℃ for 1-3h, to obtain a silica template; Step S2: According to the mass ratio of phenol source: dispersant: water = 100:1-5:500-1000, the phenol source, dispersant and water are mixed to prepare a mixed solution A; According to the mass ratio of aldehyde source: lithium supplement: catalyst: water = 100:1-5:1-5:500-1500, the aldehyde source, lithium supplement, and catalyst are added to deionized water and mixed to prepare a mixed solution B; Step S3: According to the mass ratio of mixed solution A: mixed solution B: silica template = 1000:500-1000:10-30, the mixed solution A and mixed solution B are mixed, the silica template is added and mixed uniformly, and then the reaction is carried out at a temperature of 80-150℃ for 1-6h, filtration, the obtained material is carbonized at 700-900℃ for 1-6h, then the temperature is increased to 950℃-1100℃, water vapor is introduced at a flow rate of 50-200ml / min for activation for 60-600min, then the obtained material is added to a hydrofluoric acid solution to dissolve the silica template, then the obtained material is subjected to thermal reduction at 400℃-600℃ in an inert atmosphere for 1-3h to obtain a mesoporous carbon composite material.

2. The method for preparing a mesoporous carbon composite material according to claim 1, characterized in that, The surfactant in step S1 is one of sodium dodecyl benzene sulfonate, lauryl alcohol chloride, sodium benzoate, and sulfonamide chloride; the dopant is one of graphene, carbon nanotube, and gas-phase carbon fiber.

3. The method for preparing a mesoporous carbon composite material according to claim 1, characterized in that, The phenol source in step S2 is one of phenol, cresol, catechol, and hydroquinone; the dispersant is one of polyvinyl alcohol, polypyrrolidone, polyethylene glycol, sodium dodecyl sulfonate, sodium dodecyl sulfate, cetyl ammonium bromide, and polyoxyethylene-polyoxypropylene-polyoxyethylene (F127); the aldehyde source is one of formaldehyde, acetaldehyde, acetone aldehyde, glyoxal, and furfural; the lithium supplement is one of lithium-rich lithium iron oxide, lithium-rich lithium nickelate, lithium-rich lithium cobaltate, and lithium-rich lithium manganate; the catalyst is one of sodium hydroxide, barium hydroxide, ammonia, and ammonium chloride.

4. The mesoporous carbon composite material prepared by the method according to any one of claims 1-3, wherein the mesoporous carbon composite material has a pore size of 2-10 nm, a specific surface area of 1000-1500 m 2 / g, and a pore volume of 1-1.4 cm 3 / g.

1. A method for preparing a mesoporous carbon composite material, comprising the following steps: (1) mixing a carbon source and a template to obtain a mixture; (2) shaping the mixture into a desired shape; (3) drying the mixture; (4) calcining the mixture; (5) removing the template from the mixture; and

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