A spherical porous silicon-carbon composite material, a preparation method and application thereof
By preparing spherical porous silicon-carbon composite materials and utilizing the combination of scandium-metal-organic frameworks and carboxylated polystyrene microspheres, the problems of conductivity and compaction density of silicon-carbon materials were solved, thereby improving the fast-charging performance and cycle stability of lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANG SU NA BO & XIN CAI LIAO YOU XIAN GONG SI
- Filing Date
- 2024-04-30
- Publication Date
- 2026-05-29
AI Technical Summary
The insufficient electronic conductivity and compaction density of silicon-carbon materials result in poor fast-charging and rate performance, and the insufficient compressive strength of the granular structure affects their application in lithium-ion batteries.
Spherical porous silicon-carbon composite materials were prepared by vapor deposition. By doping scandium-metal-organic frameworks into the porous carbon material, a porous structure was formed and amorphous carbon was coated, which improved the electronic conductivity and compressive strength of the material. Carboxylated polystyrene microspheres were used to form a spherical structure to improve the compaction density.
It improves the specific capacity, compressive strength and cycle performance of silicon-carbon composite materials, reduces the expansion rate of materials, and enhances the fast charging performance and cycle stability of lithium-ion batteries.
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Figure CN118495501B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery material preparation technology, and in particular to a spherical porous silicon-carbon composite material, its preparation method and application. Background Technology
[0002] Silicon-carbon materials are high-capacity, high-efficiency, and low-expansion silicon-based materials. However, their porous structure results in poor electronic conductivity, which reduces their fast-charging performance and compaction density. The main reason for the poor fast-charging performance is the low ionic or electronic conductivity, leading to poor rate performance. Improving the rate performance of silicon-carbon materials mainly involves doping the core with materials with high electronic conductivity and coating the outer shell with materials with high electronic or ionic conductivity. Simultaneously, the granular structure of silicon-carbon itself contributes to its compressive strength, reducing its compaction density. Compared to granular structures, spherical structures have stronger deformation capabilities, resulting in higher compressive strength; however, the small contact area between spheres in spherical structures leads to lower electronic conductivity, affecting rate performance. Therefore, doping is necessary to improve the rate performance of the material. Summary of the Invention
[0003] To address the problems existing in the prior art, this invention provides a spherical porous silicon-carbon composite material, its preparation method, and its application, which solves the technical problems of low compaction density and energy density, as well as poor fast-charging performance of silicon-carbon materials.
[0004] To achieve the above objectives, the technical solution adopted by the present invention includes:
[0005] The technical objective of the first aspect of this invention is to provide a method for preparing spherical porous silicon-carbon composite materials, comprising the following steps:
[0006] After mixing and drying carboxylated polystyrene microspheres, resin solution and scandium-metal-organic framework composite material, carbonization and pore formation were carried out in sequence to obtain porous carbon material;
[0007] The porous carbon material is deposited in a mixture of silane and nitrogen using a vapor phase deposition method, then passivated in a heteroatom gas, and finally deposited as amorphous carbon in a carbon source gas.
[0008] This invention involves preparing a scandium-metal-organic framework structure, followed by the deposition and passivation of nano-silicon to coat the resulting spherical porous silicon-carbon composite material. The invention utilizes internal scandium doping to enhance the material's specific capacity, while the porous structure formed after carbonization of the metal framework improves the material's compressive strength, reduces expansion, and enhances cycle performance.
[0009] Furthermore, the preparation method of the scandium-metal-organic framework composite material includes the following steps: The metal salt, organic ligand, and functional material are added to an organic solvent and dispersed evenly according to a mass ratio of metal salt: organic ligand: functional material: organic solvent of 10-50:100:1-5:500-1000; then, the mixture is ball-milled for 60-600 min at a temperature of 50-120℃ and a speed of 10-100 rpm; finally, it is washed and dried sequentially with DMF and dichloromethane to obtain the final product.
[0010] Furthermore, the metal salt includes one or more of scandium n-propoxide, scandium methacrylate, scandium acetate, scandium n-propoxide, scandium methacrylate, scandium alanine, scandium acetate, or scandium acetate; the organic ligand includes one or more of terephthalic acid, biphenyl phthalic acid, 2-methylimidazolium, trimellitic acid, or tetracarboxyphenylporphyrin; the functional material includes an organophosphorus compound that is one or more of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, tributyl phosphate, or trichloroethyl phosphate; and the organic solvent includes one or more of diethyl ether, dimethyl ether, ethylene glycol dimethyl ether, dibutyl ether, or isopropyl ether.
[0011] Furthermore, the mass ratio of the carboxylated polystyrene microspheres, the resin solution, and the scandium-metal-organic framework composite material is 5-20:100:1-10;
[0012] The resin in the resin solution is one or more of urea-formaldehyde resin, melamine-formaldehyde resin, or benzo-melamine-formaldehyde resin; the solvent in the resin solution is one or more of benzene, dichloromethane, or xylene.
[0013] The resin concentration in the resin solution is 1-5 wt%.
[0014] Furthermore, the carbonization temperature is 700-900℃, and the carbonization time is 1-6 hours;
[0015] The method for creating the pores is as follows: the temperature is raised to 1050-1250℃ and water vapor is introduced for 1-6 hours.
[0016] Furthermore, the porous carbon material is deposited in a mixed gas of silane and nitrogen at a temperature of 400-600℃, a pressure of -0.05 to -0.1 MPa, and a deposition time of 30-300 min.
[0017] In a mixture of silane and nitrogen, the volume ratio of silane to nitrogen is 0.5-2:10.
[0018] The flow rate of the silane and nitrogen mixture is 100-500 mL / min.
[0019] Furthermore, the heteroatom gas includes one or more of ammonia, phosphine, sulfur dioxide, or hydrogen boride.
[0020] The passivation temperature is 400-600℃, the passivation time is 30-300min, and the flow rate of the heteroatom gas introduced during passivation is 100-500mL / min.
[0021] Furthermore, the carbon source gas includes one or more of methane, ethane, acetylene, or ethylene.
[0022] The amorphous carbon deposition temperature is 600-800℃, and the deposition time is 30-300 min.
[0023] Specifically, a method for preparing a spherical porous silicon-carbon composite material includes the following steps:
[0024] Step S1:
[0025] According to the mass ratio of carboxylated polystyrene microspheres: resin: scandium-metal-organic framework = 5-20: 100: 1-10, carboxylated polystyrene microspheres are added to 1-5 wt% of resin solution, and scandium-metal-organic framework is added and dispersed evenly. After spray drying, the solution is transferred to a tube furnace and carbonized at 700-900℃ for 1-6 h. Then, the temperature is raised to 1050-1250℃ and activated with steam for 1-6 h to obtain porous carbon material.
[0026] Step S2:
[0027] Porous carbon material is transferred to a fluidized bed and heated to 400-600℃. Then, a silane mixed gas (volume ratio, silane:nitrogen = 0.5-2:10, flow rate 100-500 ml / min) is introduced, and deposition is carried out under negative pressure for 30-300 min. Then, a heteroatom gas is introduced, and passivation treatment is carried out at 400-600℃ and 100-500 ml / min for 30-300 min. After that, it is transferred to a rotary kiln, and amorphous carbon is deposited at 600-800℃ by a carbon source gas for 30-300 min using the vapor deposition method to obtain silicon-carbon composite material.
[0028] The technical objective of the second aspect of this invention is to provide a spherical porous silicon-carbon composite material prepared by the preparation method described above.
[0029] The technical objective of the third aspect of this invention is to provide an application of a spherical porous silicon-carbon composite material in the preparation of lithium-ion battery anode materials.
[0030] Implementing the embodiments of the present invention will have the following beneficial effects:
[0031] 1) Silicon-carbon composite materials utilize internal doping with scandium to increase the specific capacity of the material and the porous structure formed after the metal framework is carbonized to improve the compressive strength of the material and reduce expansion.
[0032] 2) The use of scandium-metal-organic framework has the characteristics of high strength, high compressive strength and high pore volume, which can increase the deposition of nano-silicon and thus improve the specific capacity of the material. At the same time, the porous structure formed after carbonization of metal-organic framework buffers the expansion of nano-silicon during charge and discharge, and improves cycle performance. In addition, the scandium-metal framework contains metallic scandium to improve the electronic conductivity of the material and improve rate performance.
[0033] 3) Carboxylated polystyrene microspheres are used, which have a spherical structure. The resin is coated on the surface of the material to form a spherical structure, which has the characteristics of high compaction density and low expansion. Attached Figure Description
[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0035] in:
[0036] Figure 1 The image shows a SEM image (2000×) of the silicon-carbon composite material prepared in Example 1.
[0037] Figure 2 The image shows a SEM image (500×) of the silicon-carbon composite material prepared in Example 1. Detailed Implementation
[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0039] Example 1
[0040] A method for preparing a scandium-metal-organic framework includes the following steps:
[0041] 30g of scandium n-propoxide, 100g of terephthalic acid, and 3g of trimethyl phosphate were added to 800g of dimethyl ether organic solvent and dispersed evenly. Then, the mixture was ball-milled in a sand mill at 80℃ and 50 rpm for 300 min to obtain the corresponding MOFs material. The MOFs material was then ultrasonically washed with DMF and dichloromethane, respectively, and finally vacuum dried at 80℃ for 24 h to obtain scandium-metal-organic framework composite material (MOFs).
[0042] A method for preparing a spherical porous silicon-carbon composite material includes the following steps:
[0043] Step S1:
[0044] 10g of carboxylated polystyrene microspheres were added to 500g of a dichloromethane solution containing urea-formaldehyde resin (the concentration of urea-formaldehyde resin in the dichloromethane solution was 2wt%), and 5g of the scandium-metal-organic framework composite material prepared in this embodiment was added. The mixture was dispersed evenly, spray-dried, and then transferred to a tube furnace for carbonization at 800℃ for 3h. After that, the temperature was raised to 1150℃ and steam (flow rate 100mL / min) was introduced for activation for 3h to obtain porous carbon material.
[0045] Step S2:
[0046] Porous carbon material was transferred to a fluidized bed and heated to 500°C. Then, a mixture of silane and nitrogen gas (volume ratio, silane:nitrogen = 1:10, flow rate 300 mL / min) was introduced and deposited under negative pressure (-0.05 MPa) for 120 min. After that, ammonia gas was introduced and passivation was performed at 500°C and 300 mL / min for 120 min. Then, the material was transferred to a rotary kiln and amorphous carbon was deposited at 700°C and 100 mL / min using vapor deposition to obtain silicon-carbon composite material.
[0047] Example 2
[0048] A method for preparing a scandium-metal-organic framework complex includes the following steps:
[0049] 10g of scandium methacrylate, 100g of biphenyl dicarboxylic acid, and 1g of triethyl phosphate were added to 500g of ethylene glycol dimethyl ether and dispersed evenly. Then, the mixture was ball-milled in a sand mill at 50℃ and 10 rpm for 600 min to obtain the corresponding MOF material. The MOF material was then ultrasonically washed with DMF and dichloromethane, and finally vacuum dried at 80℃ for 24 h to obtain scandium-metal-organic framework composite material (MOFs).
[0050] A method for preparing a spherical porous silicon-carbon composite material includes the following steps:
[0051] Step S1:
[0052] 5g of carboxylated polystyrene microspheres were added to 1000g of xylene solution containing melamine-formaldehyde resin (the concentration of melamine-formaldehyde resin in the xylene solution containing melamine-formaldehyde resin was 1wt%), and 1g of the scandium-metal-organic framework composite material prepared in this embodiment was added. The mixture was dispersed evenly, spray-dried, and then transferred to a tube furnace for carbonization at 700℃ for 6h. After that, the temperature was raised to 1050℃ and steam (flow rate 100ml / min) was introduced for activation for 6h to obtain porous carbon material.
[0053] Step S2:
[0054] Porous carbon material was transferred to a fluidized bed and heated to 400°C. Then, a mixture of silane and nitrogen gas (volume ratio, silane:nitrogen = 0.5:10, flow rate 100 mL / min) was introduced, and deposition was carried out under negative pressure (-0.05 MPa) for 300 min. After that, phosphine gas was introduced, and passivation treatment was carried out at 400°C and 100 mL / min for 300 min. Then, the material was transferred to a rotary kiln, and amorphous carbon deposition was carried out by vapor deposition at 600°C with ethylene gas (flow rate 100 mL / min) for 300 min to obtain silicon-carbon composite material.
[0055] Example 3
[0056] A method for preparing a scandium-metal-organic framework includes the following steps:
[0057] 50g scandium acetate, 100g 2-methylimidazole, and 5g tributyl phosphate were added to 1000g dibutyl ether organic solvent and dispersed evenly. Then, the mixture was ball-milled in a sand mill at 120℃ and 100 rpm for 60 min to obtain the corresponding MOFs material. The MOFs material was then ultrasonically washed with DMF and dichloromethane, and finally vacuum dried at 80℃ for 24 h to obtain scandium-metal-organic framework composites (MOFs).
[0058] A method for preparing a spherical porous silicon-carbon composite material includes the following steps:
[0059] Step S1:
[0060] 20g of carboxylated polystyrene microspheres were added to 400g of a benzene solution containing benzo-melamine-formaldehyde resin (the concentration of benzo-melamine-formaldehyde resin in the benzene solution containing benzo-melamine-formaldehyde resin was 5wt%), and 10g of the scandium-metal-organic framework composite material prepared in this embodiment was added. The mixture was dispersed evenly, spray-dried, and then transferred to a tube furnace for carbonization at 900℃ for 1h. After that, the temperature was raised to 1250℃ and activated with steam (flow rate 100mL / min) for 1h to obtain porous carbon material.
[0061] Step S2:
[0062] Porous carbon material was transferred to a fluidized bed and heated to 600°C. Then, a mixture of silane and nitrogen gas (volume ratio, silane:nitrogen = 2:10, flow rate 500 mL / min) was introduced, and deposition was carried out under negative pressure (-0.05 MPa) for 30 min. After that, hydrogen boride gas was introduced, and passivation treatment was carried out at 600°C and 500 mL / min for 30 min. Then, it was transferred to a rotary kiln, and amorphous carbon deposition was carried out at 800°C and 800°C by introducing acetylene gas (flow rate 100 mL / min) for 30 min to obtain silicon-carbon composite material.
[0063] Comparative Example 1
[0064] This comparative example provides a method for preparing a porous silicon-carbon composite material. The difference from Example 1 is that scandium-metal-organic framework composite is not added in step S1, while the rest is the same as in Example 1.
[0065] Comparative Example 2
[0066] This comparative example provides a method for preparing a porous silicon-carbon composite material. The difference from Example 1 is that carboxylated polystyrene microspheres are not added in step S1, while the rest is the same as in Example 1.
[0067] Comparative Example 3
[0068] This comparative example uses commercially available granular silicon carbide material (manufacturer: Lanxi Zhide New Energy Technology Co., Ltd., model: SO310) as the comparative example.
[0069] To compare and verify the effects of the above embodiments and comparative examples, this application conducted the following physicochemical tests on the composite materials obtained in Embodiments 1-3 and Comparative Examples 1-3:
[0070] (1) SEM test: Figures 1-2 The image shows a SEM image of the silicon-carbon composite material prepared in Example 1. Figures 1-2 As can be seen, the material exhibits a spherical structure with a porous core; the particle size D50 is between 5-10 μm, with a reasonable size distribution.
[0071] (2) Physicochemical performance testing:
[0072] The specific surface area and tap density of each silicon-carbon composite material were tested according to the national standard GB / T 38823-2020 "Silicon-Carbon". The powder resistivity of each silicon-carbon composite material was tested using a four-probe tester, and the silicon grain size of each silicon-carbon composite material was tested by XRD. The powder material was placed at 45℃ for 48 hours to test the gas production of the material. The test results are shown in Table 1 below.
[0073] Button cell battery test:
[0074] The silicon-carbon composite materials 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:
[0075] A binder, conductive agent, and solvent were added to the corresponding silicon-carbon composite materials, stirred to form a slurry, coated onto copper foil, and dried and rolled to obtain a negative electrode sheet. The binder used was LA136D, the conductive agent was SP (conductive carbon black), and the solvent was NMP. The ratio of silicon-carbon composite material, SP, LA136D, and NMP was 95g:1g:4g:220mL. 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.
[0076] Each button cell was assembled in an argon-filled glove box, and then its electrochemical performance was tested. Specifically, the electrochemical performance was tested on a Wuhan Landian CT2001A battery tester, with a charge / discharge voltage range of 0.005V to 2.0V and a charge / discharge rate of 0.1C. The test results are shown in Table 1 below.
[0077] The negative electrode of the above coin cell was also subjected to full-charge expansion. The specific test process was as follows: the thickness D1 of the negative electrode of the rolled coin cell was measured, and then the full-charge thickness D2 of the negative electrode was dissected at 100% SOC of the coin cell. The full-charge expansion rate was then calculated (full-charge expansion rate = (D2-D1) / D1*100%). The test results are shown in Table 1 below.
[0078] Table 1
[0079]
[0080]
[0081] As can be seen from the data in Table 1 above, the silicon-carbon composite materials prepared in Examples 1-3 of this application show significantly better performance in terms of initial efficiency, full charge expansion and resistivity than those in Comparative Examples 1-3. This is because the spherical structure prepared by doping polystyrene microspheres in the material reduces expansion, and the doping of scandium element reduces the impedance of porous carbon, thereby improving the specific capacity and initial efficiency of the material.
[0082] (3) Soft package performance test:
[0083] The silicon-carbon composite materials corresponding to Examples 1-3 and Comparative Examples 1-3, doped with 95% artificial graphite, were used as negative electrode materials (i.e., negative electrode sheets) and positive electrode ternary materials (LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 The battery was assembled with O2, electrolyte, and separator to form a 5Ah soft-pack battery. The separator was Celegard 2400, and the electrolyte was a LiPF6 solution (the solvent was a 1:1 volume ratio of EC and DEC mixed solution, and the concentration of LiPF6 was 1.1mol / L).
[0084] The following performance tests were performed on each pouch battery:
[0085] a. Ratio test: The constant current ratio of Examples 1-3 and Comparative Examples 1-3 under 2C conditions was tested simultaneously. The constant current ratio = 2C constant current capacity / (2C constant current capacity + 0.1C constant voltage capacity).
[0086] b. Cyclic performance test: Cyclic performance tests were conducted on each of the prepared pouch cells. The test conditions for the cycle performance test were as follows: charge and discharge voltage range of 2.5 to 4.2V, temperature of 25±3.0℃, charge and discharge rate of 1.0C / 1.0C, and 500 cycles. The test results are shown in Table 2 below.
[0087] Table 2
[0088] 2C constant current ratio Cyclic performance Example 1 93.7％ 94.8％ Example 2 92.2％ 95.1％ Example 3 94.3％ 94.2％ Comparative Example 1 87.8％ 91.6％ Comparative Example 2 89.9％ 90.3％ Comparative Example 3 90.5％ 89.5％
[0089] As can be seen from Table 2 above, the rate performance, cycle performance, and liquid absorption capacity of the soft-pack lithium-ion batteries prepared using the silicon-carbon composite materials provided in Examples 1-3 are significantly better than those of Comparative Examples 1-3. This is because the materials in the examples have a high specific surface area, which improves the liquid absorption capacity of the materials, and low full-charge expansion, which improves the cycle performance. At the same time, the doping of scandium metal in the materials of the examples reduces the resistivity of the powder, increases the constant current ratio of the materials, and improves the rate performance.
[0090] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.
Claims
1. A method for preparing a spherical porous silicon-carbon composite material, characterized in that, Includes the following steps: After mixing and drying carboxylated polystyrene microspheres, resin solution and scandium-metal-organic framework composite material, carbonization and pore formation were carried out in sequence to obtain porous carbon material; The porous carbon material is deposited in a mixed gas of silane and nitrogen using a vapor phase deposition method, then passivated in a heteroatom gas, and finally deposited as amorphous carbon in a carbon source gas to obtain the desired product. The mass ratio of the carboxylated polystyrene microspheres, the resin solution, and the scandium-metal-organic framework composite material is 5-20:100:1-10. The resin in the resin solution is one or more of urea-formaldehyde resin, melamine-formaldehyde resin, or benzo-melamine-formaldehyde resin; the solvent in the resin solution is one or more of benzene, dichloromethane, or xylene. The resin concentration in the resin solution is 1-5 wt%.
2. The preparation method according to claim 1, characterized in that, The preparation method of the scandium-metal-organic framework composite material includes the following steps: The metal salt, organic ligand, and functional material are added to an organic solvent and dispersed evenly according to a mass ratio of metal salt: organic ligand: functional material: organic solvent of 10-50:100:1-5:500-1000; then, the mixture is ball-milled for 60-600 min at a temperature of 50-120℃ and a speed of 10-100 rpm; finally, it is washed and dried sequentially with DMF and dichloromethane to obtain the final product.
3. The preparation method according to claim 2, characterized in that, The metal salt includes one or more of scandium n-propoxide, scandium methacrylate, scandium acetate, or scandium alanine; the organic ligand includes one or more of terephthalic acid, biphenyl phthalic acid, 2-methylimidazolium, trimellitic acid, or tetracarboxyphenylporphyrin; the functional material includes one or more of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, tributyl phosphate, or trichloroethyl phosphate; and the organic solvent includes one or more of diethyl ether, dimethyl ether, ethylene glycol dimethyl ether, dibutyl ether, or isopropyl ether.
4. The preparation method according to claim 1, characterized in that, The carbonization temperature is 700-900℃, and the carbonization time is 1-6 hours; The method for creating the pores is as follows: the temperature is raised to 1050-1250℃ and water vapor is introduced for 1-6 hours.
5. The preparation method according to claim 1, characterized in that, The porous carbon material is deposited in a mixed gas of silane and nitrogen at a temperature of 400-600℃, a pressure of -0.05~-0.1 MPa, and a deposition time of 30-300 min. In a mixture of silane and nitrogen, the volume ratio of silane to nitrogen is 0.5-2:
10. The flow rate of the silane and nitrogen mixture is 100-500 mL / min.
6. The preparation method according to claim 1, characterized in that, The heteroatom gas includes one or more of ammonia, phosphine, sulfur dioxide, or hydrogen boride. The passivation temperature is 400-600℃, the passivation time is 30-300min, and the flow rate of the heteroatom gas introduced during passivation is 100-500mL / min.
7. The preparation method according to claim 1, characterized in that, The carbon source gas includes one or more of methane, ethane, acetylene, or ethylene. The amorphous carbon deposition temperature is 600-800℃, and the deposition time is 30-300 min.