A mesoporous carbon composite material and its preparation method

Abstract

This invention discloses a mesoporous carbon composite material and its preparation method. The preparation method is as follows: S1: Using tetraethyl orthosilicate as the silicon source, an ethanol / deionized water mixture, a surfactant as the solvent system, and a conductive agent as the dopant, a polycondensation reaction is carried out under acid-base catalysis. A silica / soft template composite is formed through a sol-gel process, followed by high-temperature sintering to obtain a silica composite template; S2: A mixed solution A is prepared by mixing a phenol source, a dispersant, and water; a mixed solution B is prepared by mixing an aldehyde source, a lithium supplement, and a catalyst; S3: Mixed solutions A, B, and the silica composite template are reacted, carbonized, and activated. The resulting material is then added to a hydrofluoric acid solution to dissolve the template, and the resulting material undergoes thermal reduction to obtain the mesoporous carbon composite material. The mesoporous carbon prepared using the template method exhibits advantages such as high uniformity, large pore volume, and low powder resistivity. It can be applied to silicon-carbon composite materials to increase the deposition amount of nano-silicon, improve specific capacity, and reduce the expansion of silicon-carbon materials.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation, specifically a mesoporous carbon composite material and its preparation method. Background Technology

[0002] Silicon-carbon materials are the primary choice for high-energy-density anode materials. The extent of their expansion and power output significantly impacts battery expansion, cycle life, and fast charging during application. Currently, porous carbon used in silicon-carbon materials is prepared from resin or biomass through pre-carbonization and activation. This results in small pore sizes, low pore volumes, and poor uniformity, leading to significant expansion. Mesoporous carbon, on the other hand, offers advantages such as large pore sizes, high pore volumes, fewer defects, and good uniformity, reducing the expansion of nano-silicon during charging and discharging. Currently, the market primarily uses template methods to prepare mesoporous carbon. For example, patent application CN201811021947.5 discloses a method and application for preparing high specific surface area macroporous mesoporous carbon using a salt template. The preparation method involves dissolving biomass gelatin in hot water to form a sol, adding inorganic salts as a template agent to prepare an aerogel, and then sintering at high temperature. However, carbon materials prepared by this patented method suffer from poor power performance and numerous defects, resulting in low initial efficiency. Summary of the Invention

[0003] To improve the power performance and first-pass efficiency of mesoporous carbon, this invention prepares a conductive agent-doped silica template, deposits lithium-doped phenolic resin on the surface of the mesoporous carbon, activates it, and removes the template to obtain conductive agent / lithium-doped mesoporous carbon, thereby improving the power and first-pass efficiency of the mesoporous carbon.

[0004] A method for preparing a mesoporous carbon composite material, characterized by comprising the following steps:

[0005] Step S1:

[0006] Weigh out the following components: tetraethyl orthosilicate, ethanol / deionized water mixture, surfactant, and dopant in a mass ratio of 100:200-300:0.5-2:1-5. Dissolve the surfactant in deionized water to prepare a solution with a mass concentration of 0.5-2 wt%. Then add tetraethyl orthosilicate, the ethanol / deionized water mixture, and the dopant. Mix thoroughly. Add 0.1 mol / L hydrochloric acid to hydrolyze the solution. Then add 0.1 mol / L ammonia to adjust the pH to 6-8. Perform a polycondensation reaction, filter, and sinter at 800-1100℃ for 1-3 hours to obtain a silica template.

[0007] Step S2:

[0008] Mix the phenol source, dispersant, and water at a mass ratio of 100:1-5:500-1000 to prepare mixed solution A;

[0009] Weigh out the aldehyde source, lithium supplement, catalyst and water in a mass ratio of 100:1-5:1-5:500-1500, add the aldehyde source, lithium supplement and catalyst to deionized water and mix to prepare mixed solution B.

[0010] Step S3:

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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

[0015] 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.

[0016] 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.

[0017] 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

[0018] Figure 1 The image shows a SEM image of the mesoporous carbon composite material prepared in Example 1. Detailed Implementation

[0019] Example 1

[0020] A method for preparing a mesoporous carbon composite material includes the following steps:

[0021] Step S1:

[0022] 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.

[0023] Step S2:

[0024] Mix 100g of phenol, 3g of polyvinyl alcohol and 800g of water to prepare mixed solution A;

[0025] Mix 100g formaldehyde, 3g lithium iron ferrite, and 3g sodium hydroxide in 800g deionized water to prepare mixed solution B.

[0026] Step S3:

[0027] 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.

[0028] Example 2

[0029] A method for preparing a mesoporous carbon composite material includes the following steps:

[0030] Step S1:

[0031] 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.

[0032] Step S2:

[0033] Mix 100g of cresol, 1g of polypyrrolidone and 500ml of water to prepare mixed solution A;

[0034] 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.

[0035] Step S3:

[0036] 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.

[0037] Example 3

[0038] A method for preparing a mesoporous carbon composite material includes the following steps:

[0039] Step S1:

[0040] 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.

[0041] Step S2:

[0042] Mix 100g of catechol, 5g of polyethylene glycol and 1000g of water to prepare mixed solution A;

[0043] 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.

[0044] Step S3:

[0045] 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.

[0046] Comparative Example 1:

[0047] Unlike Example 1, step S3 does not involve adding a silica template; otherwise, it is the same as Example 1.

[0048] 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.

[0049] Comparative Example 2:

[0050] Unlike Example 1, step S2 does not involve the addition of lithium-rich lithium iron phosphate; otherwise, it is the same as Example 1.

[0051] I. Scanning electron microscope image

[0052] 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.

[0053] II. Physicochemical and Button Cell Testing

[0054] 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.

[0055]

[0056] 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.

[0057] 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.

[0058] Then, the following performance tests were performed on each button cell:

[0059] (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.

[0060] (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.

[0061] (3) The lithium-ion diffusion coefficient of the material was tested by GITT. The test results are shown in Table 2.

[0062]

[0063] 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.

[0064] 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, Includes the following steps: Step S1: Weigh out tetraethyl orthosilicate, ethanol / deionized water mixture, surfactant, and dopant in a mass ratio of 100:200-300:0.5-2:1-5. Dissolve the surfactant in deionized water to prepare a solution with a mass concentration of 0.5-2wt%. Then add tetraethyl orthosilicate, ethanol / deionized water mixture, and dopant. Mix thoroughly. Add 0.1mol / L hydrochloric acid to hydrolyze the solution. Then add 0.1mol / L ammonia to adjust the pH to 6-8. Perform polycondensation reaction, filter, and sinter at 800-1100℃ for 1-3 hours to obtain a silica template. Step S2: According to the mass ratio of phenol source: dispersant: water = 100: 1-5: 500-1000, mix the phenol source, dispersant and water to prepare mixed solution A; According to the mass ratio of aldehyde source: lithium supplement: catalyst: water = 100: 1-5: 1-5: 500-1500, add the aldehyde source, lithium supplement, and catalyst to deionized water and mix to prepare mixed solution B. Step S3: Mix solution A: Mix solution B: Silica template in a mass ratio of 1000:500-1000:10-30, mix solution A and solution B, add silica template and mix evenly, react at 80-150℃ for 1-6 hours, filter, carbonize the obtained material at 700-900℃ for 1-6 hours, then heat to 950℃-1100℃ and pass water vapor at a flow rate of 50-200 ml / min for 60-600 minutes, then add the obtained material to hydrofluoric acid solution to dissolve the silica template, and then thermally reduce the obtained material at 400℃-600℃ under an inert atmosphere for 1-3 hours to obtain mesoporous carbon composite material; 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. 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 ferrite, lithium-rich lithium nickel ferrite, lithium-rich lithium cobalt ferrite, or lithium-rich lithium manganese ferrite; and the catalyst is one of sodium hydroxide, barium hydroxide, ammonia, or ammonium chloride.

2. The mesoporous carbon composite material prepared by the method of claim 1, 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.

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