Preparation method of snco-doped hard carbon composite material and sodium ion battery thereof
By doping SnCo alloying elements into hard carbon materials, SnCo-doped hard carbon composite materials were prepared, which solved the problems of insufficient conductivity and specific capacity of hard carbon materials and improved the electrochemical performance of sodium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 河北坤天新能源股份有限公司
- Filing Date
- 2025-07-22
- Publication Date
- 2026-08-04
AI Technical Summary
Hard carbon materials in sodium-ion batteries suffer from poor electronic conductivity, numerous surface defects, low initial efficiency, low specific capacity, and insufficient power performance. Existing improvement measures offer limited gains in specific capacity and power performance.
Porous tin/graphene compounds were prepared by doping hard carbon materials with SnCo alloying elements, and then mixed with cobalt powder to form SnCo-doped hard carbon composite materials. Graphene was used to improve electrical conductivity, the porous structure buffered charge and discharge expansion, and sodium salt compounds were used to reduce SEI film consumption.
It significantly improves the specific capacity, initial efficiency, and rate performance of hard carbon materials, improves material expansion and liquid retention during charge and discharge, and enhances the electrochemical performance of sodium-ion batteries.
Smart Images
Figure CN120841501B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of sodium-ion battery material preparation, specifically a method for preparing SnCo-doped hard carbon composite material and its sodium-ion battery. Background Technology
[0002] The main anode materials for sodium-ion batteries include carbon-based materials (such as hard carbon), titanium-based materials, and alloy materials. However, titanium-based materials have poor air stability, making them difficult to synthesize and apply. While alloy materials have high specific capacity, their large expansion during use makes mass production difficult in the short term. Hard carbon, as a mature material, has attracted attention due to its wide availability, good low-temperature performance, and low expansion, and is used in lithium-ion batteries and sodium-ion batteries. However, compared to graphite, hard carbon has lower electronic conductivity and more surface defects, resulting in poor rate performance at room temperature, low initial efficiency, and low specific capacity. Measures to improve the initial efficiency, power performance, and specific capacity of hard carbon materials include introducing non-metallic / metallic elements, surface treatment, and doping with alloying elements to enhance specific capacity, power performance, and initial efficiency. For example, patent application number CN202210327614.5 discloses a metal oxide amorphous carbon-coated hard carbon composite material, its preparation method and application. It mainly involves dissolving a hard carbon precursor material and a catalyst solution in an organic solvent to obtain a hard carbon precursor solution; then mixing asphalt with the organic solvent, adding a metal organometallic compound, adding the hard carbon precursor solution, and carbonizing to obtain a metal-doped amorphous carbon-coated hard carbon composite material. However, since doping the outer shell with metal oxides only improves the power performance of the outer shell, the power improvement of the material is limited, and the specific capacity of the material is not improved. Summary of the Invention
[0003] To improve the power performance and specific capacity of hard carbon, this invention improves the specific capacity and power performance of starch-based hard carbon by doping it with SnCo alloying elements, which have a high specific capacity. Simultaneously, a method for preparing SnCo-doped hard carbon composite materials is provided.
[0004] A method for preparing SnCo-doped hard carbon composite material, characterized by comprising the following steps: Step S1: According to the mass ratio of organotin compound: graphene oxide: sodium salt compound = 1-5: 1-5: 1-5, the organotin compound is added to an organic solvent to prepare a 5-20 wt% solution. Then, the graphene oxide solution is added, the sodium salt compound is evenly dispersed, and the reaction is carried out by hydrothermal reaction at a temperature of 100-200℃ for 1-6 hours to obtain tin-cobalt / graphene composite.
[0005] This invention controls the reaction temperature at 100-200℃, which can improve the yield of porous tin / graphene compounds. Too low a temperature will lead to low reaction efficiency, and the hydrogen / carboxyl groups on the surface of graphene oxide, the organic groups on the surface of organotin compounds, and the sodium ions on the surface of sodium salt compounds will not react sufficiently. Too high a temperature will destroy the structural stability of the materials. Afterwards, freeze-drying is carried out at a temperature of -20℃ to 60℃ for 24 hours. This invention uses freeze-drying at this temperature to ensure that the materials have many pores while maintaining a stable pore structure, and thus prepares porous tin / graphene compounds. Step S2: According to the mass ratio of porous tin / graphene compound: cobalt powder = 1-10: 1-10, the porous tin / graphene compound and cobalt powder are added to a ball mill and ground and mixed evenly. The resulting material is then transferred to a tube furnace and sintered at a temperature of 600-1000℃ for 1-6 hours to obtain a tin-cobalt / graphene composite. Step S3: According to the mass ratio of tin cobalt / graphene composite to starch = 1-10:100, starch was added to deionized water to prepare a starch solution with a mass concentration of 1wt%-10wt%. Then, tin cobalt / graphene composite was added and dispersed evenly. After spray drying, the resulting material was transferred to a tube furnace and heated to 500-800℃ for 1-6 hours under an inert atmosphere. Then, the temperature was increased to 1000-1800℃ and sintered for 1-10 hours to obtain SnCo-doped hard carbon composite material.
[0006] The organotin compound in step S1 is one of stannous oxalate, phenylbutanedinium, tin oleate, tetraphenyltin, triphenyltin acetate, and stannous dicero.
[0007] The concentration of the graphene oxide solution in step S1 is 0.5wt%-5wt%.
[0008] The sodium salt compound in step S1 is one of sodium dihydrogen phosphate, sodium phosphate, sodium phosphomolybdate, sodium phytate, or sodium metaphosphate.
[0009] In step S2, the particle size of the cobalt powder is between 100-500 nm.
[0010] Step S1 The starch is one of the following: red pigment starch, corn starch, wheat starch, potato starch, and pea starch.
[0011] The present invention also provides a sodium-ion battery, comprising a positive electrode, a negative electrode, and a separator, wherein the negative electrode of the sodium-ion battery is coated with a SnCo-doped hard carbon composite material. Beneficial effects
[0012] By using a chemical method to prepare porous tin / graphene compounds and doping them with cobalt powder, SnCo compounds are generated and doped into hard carbon, while graphene is doped into the pores or surface of the porous tin. The graphene is used to improve the electrical conductivity of the material, and the porous tin structure can buffer the expansion of the material during charging and discharging. At the same time, the porous structure formed after the carbonization of organotin compounds is used to reduce the expansion of the alloy material and improve its liquid retention performance.
[0013] Sodium salt compounds are obtained by doping the material with sodium salt compounds and then carbonizing it. This reduces the sodium ions consumed in the formation of the SEI film during charging and discharging, thereby improving the first efficiency and rate performance. Attached Figure Description
[0014] Figure 1 The image shows a SEM image of the SnCo-doped hard carbon composite material prepared in Example 1. Detailed Implementation
[0015] Example 1 A method for preparing SnCo-doped hard carbon composite material includes the following steps: Step S1: 3g of stannous oxalate was added to 300g of N-methylpyrrolidone to prepare a 10wt% solution. Then, 300g of N-methylpyrrolidone solution containing 1wt% graphene oxide was added, and 3g of sodium dihydrogen phosphate was dispersed evenly. The solution was then transferred to a high-pressure reactor and reacted at 150℃ and 3MPa for 3h. After filtration, the filter residue was freeze-dried at -40℃ for 24h to prepare a porous tin / graphene compound. Step S2: 5g of porous tin / graphene compound and 5g of metallic cobalt powder were added to a ball mill and ground and mixed evenly. Then, the mixture was transferred to a tube furnace and sintered at 800℃ for 3h to obtain a tin-cobalt / graphene composite. Step S3: 5g of tin-cobalt / graphene composite was added to 2000g of starch solution with a mass concentration of 5wt%, dispersed evenly, spray-dried, and then transferred to a tube furnace. Under a nitrogen inert atmosphere, the temperature was first raised to 600℃ and held for 3h, and then raised to 1400℃ and sintered for 6h to obtain SnCo-doped hard carbon composite material. Example
[0016] A method for preparing SnCo-doped hard carbon composite material includes the following steps: Step S1: 1g of phenylbutanedinium was added to 20g of cyclohexane organic solvent to prepare a 5wt% solution. Then, 200g of N-methylpyrrolidone solution of 0.5wt% graphene oxide and 1g of sodium phosphate were added and dispersed evenly. The mixture was then transferred to a high-pressure reactor and reacted at 100℃ for 6h. After that, it was freeze-dried at -40℃ for 24h to prepare a porous tin / graphene compound. Step S2: 1g of porous tin / graphene compound and 1g of metallic cobalt powder were added to a ball mill and ground and mixed evenly. The resulting material was then transferred to a tube furnace and sintered at 600℃ for 6h to obtain a tin-cobalt / graphene composite. Step S3: 1g of tin-cobalt / graphene composite was added to 10000g of starch solution with a mass concentration of 1wt%, dispersed evenly, and spray-dried. The resulting material was transferred to a tube furnace and heated to 500℃ for 6h under an argon inert atmosphere, then heated to 1000℃ and sintered for 10h to obtain SnCo-doped hard carbon composite material. Example
[0017] A method for preparing SnCo-doped hard carbon composite material includes the following steps: Step S1: 5g of tetraphenyltin was added to 25g of carbon tetrachloride organic solvent to prepare a 20wt% solution. Then, 100g of N-methylpyrrolidone solution of graphene oxide (5wt%) and 5g of sodium phosphomolybdate were added and dispersed evenly. The mixture was then transferred to a high-pressure reactor and reacted at 200℃ for 1h. After that, it was freeze-dried at -40℃ for 24h to prepare a porous tin / graphene compound. Step S2: 10g of porous tin / graphene compound and 10g of metallic cobalt powder were added to a ball mill and ground and mixed evenly. The resulting material was then transferred to a tube furnace and sintered at 1000℃ for 1h to obtain a tin-cobalt / graphene composite. Step S3: 10g of tin-cobalt / graphene composite was added to 1000g of starch solution with a mass concentration of 10wt%, dispersed evenly, spray-dried, and then the resulting material was transferred to a tube furnace and heated to 800℃ for 1h under an argon inert atmosphere, and then heated to 1800℃ for 1h to obtain SnCo-doped hard carbon composite material.
[0018] Comparative Example 1: No tin compound is added; its detailed preparation process is as follows: 3g of sodium dihydrogen phosphate was added to 300g of N-methylpyrrolidone solution containing 1wt% graphene oxide and dispersed evenly. The solution was then transferred to a high-pressure reactor and reacted at 150℃ and 3MPa for 3 hours. After filtration, the resulting filter residue was freeze-dried at -40℃ for 24 hours to prepare phosphorus-doped graphene compounds. 5g of phosphorus-doped graphene compound and 5g of metallic cobalt powder were added to a ball mill and ground and mixed evenly. Then, the mixture was transferred to a tube furnace and sintered at 800℃ for 3 hours to obtain a cobalt-graphene composite. Then, 5g of cobalt graphene composite was added to 2000g of starch solution with a mass concentration of 5wt%, dispersed evenly, spray-dried, and then transferred to a tube furnace. Under an inert argon atmosphere, the temperature was first raised to 600℃ and held for 3h, and then raised to 1400℃ and sintered for 6h to obtain Co-doped hard carbon composite material.
[0019] Comparative Example 2: Undoped of cobalt; the detailed preparation process is as follows: Take 5g of the porous tin / graphene compound from step S1 in the example, transfer it to a tube furnace and sinter it at 800℃ for 3h to obtain a tin-graphene composite. Then, 5g of tin-graphene composite was added to 2000g of starch solution with a mass concentration of 5wt%, dispersed evenly, spray-dried, and then transferred to a tube furnace. Under an inert argon atmosphere, the temperature was first raised to 600℃ and held for 3h, and then raised to 1400℃ and sintered for 6h to obtain Sn-doped hard carbon composite material.
[0020] 1. SEM testing The SnCo-doped hard carbon composite material prepared in Example 1 was subjected to SEM testing, and the results are as follows: Figure 1 As shown in the figure, the hard carbon material prepared in Example 1 has a granular structure with uniform size distribution. The bright-colored material on the surface is SnCo compound with a particle size of 5-10 μm.
[0021] 2. Physical and chemical properties and button cell testing The particle size, tap density, specific surface area, trace element content (Sn and Co), and specific capacity of the hard carbon composite materials prepared in Examples 1-3 and the comparative examples were tested.
[0022] Test method: GBT-24533-2019 "Graphite-based negative electrode materials for lithium-ion batteries".
[0023] SnCo-doped hard carbon composite materials obtained in Examples 1-3 and Comparative Examples 1-2 were assembled into coin cells A1, A2, A3, B1, and B2, respectively. The preparation method was as follows: binder, conductive agent, and solvent were added to the negative electrode material, stirred and slurried, coated on copper foil, and dried and rolled to obtain the final product. The binder used was LA132 binder, the conductive agent was SP, and the negative electrode material was the hard carbon material prepared in Examples 1-3 and Comparative Examples 1-2, respectively. The solvent was double-distilled water, and the ratio was: negative electrode material: SP: LA132: double-distilled water = 94g: 2g: 4g: 220mL, and a negative electrode sheet was prepared. The electrolyte was NaPF6 / EC+DEC (volume ratio 1:1, concentration 1.1mol / L), the sodium metal sheet was used as the counter electrode, and the separator was made of polyethylene (PE), polypropylene (PP), or polyethylene propylene (PEP) composite membrane. The simulated battery was assembled in an argon-filled glove box, and the electrochemical performance was tested on a Wuhan Landian CT2001A battery tester. The charge / discharge voltage range was 0.00V to 2.0V, and the charge / discharge rate was 0.1C. The rate capability (2C / 0.1C) and cycle performance (0.2C / 0.2C, 200 cycles) of the coin cell were also tested. The test results are shown in Table 1 below. Table 1
[0024] As shown in Table 1, compared with the comparative examples, the SnCo-doped hard carbon composite materials prepared in Examples 1-3 exhibit significantly improved initial discharge specific capacity, initial efficiency, rate performance, and cycle performance. This is because, in this invention, tin-cobalt doping enhances the electronic conductivity and specific capacity of the material, thereby improving the rate performance. Simultaneously, the SnCo composite material reduces the irreversible capacity of the material and increases the sodium ion insertion / extraction rate during charge and discharge, thus improving the rate performance.
[0025] 3. Soft-pack battery test: The SnCo-doped hard carbon composite materials from Examples 1-3 and Comparative Examples 1-2 were used as negative electrodes, and negative electrode sheets were prepared by slurry mixing and coating, using layered oxides (NaFe) 1 / 3 Mn 1 / 3 Ni 1 / 3 A 2Ah pouch cell was prepared using O2 as the positive electrode, NaPF6 (solvent EC+DEC, volume ratio 1:1, concentration 1.3mol / L) as the electrolyte, and Celgard 2400 as the separator.
[0026] 3.1 High-Temperature Storage Performance Test: Test method: The test conditions are as follows: the battery capacity in a fully charged state is tested at 60℃ and recorded as X1. After being placed at 60℃ for 30 days, the battery capacity is tested again and recorded as X2. The charge retention is calculated as X2 / X1*100%. Then, the battery is fully charged to a full state (100% SOC) and its capacity is tested as X3. The recovery capacity is calculated as X3 / X1*100%. 3.2 Cyclic performance: Temperature 25±3℃, 1C / 1C, 500 cycles; results are detailed in Table 2.
[0027] Table 2
[0028] As can be seen from Table 2, the high-temperature storage performance of the material in the example is better than that of the comparative example. This is because the SnCo compound is doped into the material. The compound has the characteristics of stable structure, high specific capacity and good power performance, and the synergistic effect between the two can improve the cycle and storage performance.
[0029] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing SnCo-doped hard carbon composite material, characterized in that, Includes the following steps: Step S1: According to the mass ratio of organotin compound: graphene oxide: sodium salt compound = 1-5: 1-5: 1-5, the organotin compound was added to an organic solvent to prepare a 5wt%-20wt% solution. Then, the graphene oxide solution was added, and the sodium salt compound was evenly dispersed. The reaction was carried out by hydrothermal reaction at a temperature of 100-200℃ for 1-6 hours, followed by freeze drying at a temperature of -40℃ for 24 hours to prepare a porous tin / graphene compound. Step S2: According to the mass ratio of porous tin / graphene compound: cobalt powder = 1-10: 1-10, the porous tin / graphene compound and cobalt powder are added to a ball mill and ground and mixed evenly. The resulting material is then transferred to a tube furnace and sintered at a temperature of 600-1000℃ for 1-6 hours to obtain a tin-cobalt / graphene composite. Step S3: According to the mass ratio of tin cobalt / graphene composite to starch = 1-10:100, starch was added to deionized water to prepare a starch solution with a mass concentration of 1wt%-10wt%. Then, tin cobalt / graphene composite was added and dispersed evenly. After spray drying, the resulting material was transferred to a tube furnace and heated to 500-800℃ for 1-6 hours under an inert atmosphere. Then, the temperature was increased to 1000-1800℃ and sintered for 1-10 hours to obtain SnCo-doped hard carbon composite material.
2. The method for preparing a SnCo-doped hard carbon composite material according to claim 1, characterized in that, The organotin compound in step S1 is one of stannous oxalate, phenylbutanedinium, tin oleate, tetraphenyltin, triphenyltin acetate, and stannous dicero.
3. The method for preparing a SnCo-doped hard carbon composite material according to claim 1, characterized in that, The concentration of the graphene oxide solution in step S1 is 0.5wt%-5wt%.
4. The method for preparing a SnCo-doped hard carbon composite material according to claim 1, characterized in that, The sodium salt compound in step S1 is one of sodium dihydrogen phosphate, sodium phosphate, sodium phosphomolybdate, sodium phytate, or sodium metaphosphate.
5. The method for preparing a SnCo-doped hard carbon composite material according to claim 1, characterized in that, In step S2, the particle size of the cobalt powder is between 100-500 nm.
6. The method for preparing a SnCo-doped hard carbon composite material according to claim 1, characterized in that, The starch in step S3 is one of the following: red pigment starch, corn starch, wheat starch, potato starch, or pea starch.