Preparation method of high specific capacity silicon-carbon negative electrode material

Abstract

The application relates to the technical field of electrode materials, in particular to a preparation method of a high-specific-capacity silicon-carbon negative electrode material. The method solves the capacity attenuation problem caused by the volume expansion of a silicon-based material through multi-stage structure design, and specifically comprises the following steps: (1) adopting an EDC / NHS activation system to perform surface modification on carboxylated porous carbon, and forming a stable three-dimensional network through carboxylic acid-polyethylene glycol-carboxylic acid bridging; (2) realizing uniform compounding of nano-silicon powder and modified porous carbon through a supercritical CO2 assisted dispersion technology; and (3) combining an electrostatic spinning process and a gradient calcination process to form a composite carbon layer structure. The obtained material has a first discharge capacity of 2052 mAh / g, a cycle capacity retention rate of 92.5% after 2000 cycles, and a volume expansion rate of only 12.4%, and exhibits excellent cycle stability and volume stability, and is suitable for high-energy-density lithium ion batteries.

Description

Technical Field

[0001] This invention relates to the field of electrode materials technology, and in particular to a method for preparing a high-specific-capacity silicon-carbon anode material. Background Technology

[0002] As a new generation of energy storage devices, lithium-ion batteries have attracted much attention for the development of their anode materials. Silicon-based materials are considered the most promising next-generation anode materials due to their theoretical specific capacity (4200 mAh / g) far exceeding that of traditional graphite anodes (372 mAh / g). However, silicon undergoes a volume expansion of over 300% during charging and discharging, leading to electrode structure pulverization, conductive network damage, and continuous SEI film growth, which severely restricts its practical application.

[0003] Existing technologies mainly improve the performance of silicon anodes through the following approaches: (1) Nanoscale design: reduce absolute volume change by preparing nano-silicon particles, but nanoparticles are prone to agglomeration and have low tap density; (2) Carbon coating structure: use carbon materials to wrap silicon particles to buffer volume expansion, but traditional mechanical mixing methods have problems such as weak interface bonding and discontinuous conductive network; (3) Porous structure design: construct a porous structure to reserve expansion space, but sacrifice the material energy density.

[0004] The common problems with existing technologies are: 1) insufficient bonding strength between carbon materials and silicon particles, leading to easy interface delamination during cycling; 2) imperfect conductive network, unable to adapt to repeated volume changes in silicon; and 3) insufficient density of the carbon layer structure, making it difficult to effectively suppress excessive SEI film growth caused by electrolyte penetration. Therefore, developing silicon-carbon composite anode materials with stable interface bonding, a complete conductive network, and gradient structure protection has become an urgent technical challenge. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a method for preparing a high-specific-capacity silicon-carbon anode material, so as to solve the problems of rapid capacity decay, poor structural stability and imperfect conductive network caused by the silicon volume expansion effect in existing silicon-carbon anode materials.

[0006] To achieve the above objectives, the present invention provides a method for preparing a high-specific-capacity silicon-carbon anode material, comprising the following steps:

[0007] (1) Add ammonium persulfate to a sulfuric acid aqueous solution with a concentration of 2 mol / L, stir for 20-40 min, then add porous carbon, stir at 55-65℃ for 4-6 h, wash, and dry to obtain carboxylated porous carbon;

[0008] (2) Carboxylated multi-walled porous carbon and carboxylic acid-polyethylene glycol-carboxylic acid are dispersed together in an activation solution, ultrasonically treated for 1-3 hours, then triethylenetetramine is added, and under nitrogen protection, the mixture is stirred at 55-65℃ for 5-7 hours. After centrifugation, washing, and drying, modified porous carbon is obtained.

[0009] (3) Add the modified porous carbon and Fe(NO3)3·9H2O to an ethanol / water solvent and sonicate for 1-3 hours to obtain a dispersion;

[0010] (4) Add nano-silicon powder and dispersion into a supercritical reactor and stir at 200-400 rpm for 3-5 hours. Then put it into a centrifugal spray dryer to obtain silicon composite.

[0011] (5) Add the silicon composite to the polyacrylonitrile / DMF solution, use an electrospinning machine with a voltage of 16-20kV, a receiving distance of 14-16cm, and a spinning rate of 1-1.5mL / h. After spinning, calcine in a tube furnace and grind through a 200-mesh sieve to obtain a silicon-carbon anode material with high specific capacity.

[0012] Preferably, in step (1), the weight ratio of ammonium persulfate, sulfuric acid aqueous solution and porous carbon is 20-30:80-120:0.8-1.2.

[0013] Preferably, in step (2), the ratio of carboxylated multi-walled porous carbon, carboxylic acid-polyethylene glycol-carboxylic acid, activation solution and triethylenetetramine is 0.6-1g:0.2g-0.6g:150mL-250mL:0.1g-0.2g.

[0014] Preferably, in step (2), the outer diameter of the carboxylated multi-walled porous carbon is 4-8 nm and the length is 10-20 μm.

[0015] Preferably, in step (2), the Mn of carboxylic acid-polyethylene glycol-carboxylic acid is 600.

[0016] Preferably, the activation solution in step (2) is a phosphate buffer system activation solution containing 0.1M 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 0.05M N-hydroxysuccinimide (NHS), with a pH of 5.5.

[0017] Preferably, the ethanol / water solvent in step (3) contains 1.5wt%-2.5wt% modified porous carbon and 0.1wt%-1wt% Fe(NO3)3·9H2O.

[0018] Preferably, the volume ratio of ethanol to water in the ethanol / water solvent in step (3) is 2-4:1.

[0019] Preferably, the particle size of the nano-silicon powder in step (4) is 20-60 nm.

[0020] Preferably, in step (4), the CO2 pressure of the supercritical reactor is 15-25 MPa, the temperature is 45-55℃, the inlet temperature of the centrifugal spray dryer is 180-220℃, the outlet temperature is 70-90℃, and the atomizing disc speed is 15000-20000 rpm.

[0021] Preferably, the weight ratio of nano-silicon powder to dispersion in step (4) is 10:80-120.

[0022] Preferably, in step (5), the weight ratio of silicon composite to polyacrylonitrile / DMF solution is 1:5.

[0023] Preferably, the polyacrylonitrile concentration in the polyacrylonitrile / DMF solution in step (5) is 5wt%-10wt%.

[0024] Preferably, in step (5), the voltage of the electrospinning machine is 16-20kV, the receiving distance is 14-16cm, and the spinning rate is 1-1.5mL / h.

[0025] Preferably, the calcination process in step (5) is as follows: the temperature is increased to 250-300℃ at 0.5-1.5℃ / min and held for 0.5-1.5h, then increased from 250-300℃ to 550-650℃ at 1.5-2.5℃ / min, C2H2 / Ar (volume ratio 1:15) is introduced for 2-4h, then increased to 820-870℃ at 2.5-3.5℃ / min, and then treated with H2 / CH4 (1:9) for 1-3h, and then cooled to room temperature.

[0026] Preferably, the Mw of polyacrylonitrile in step (5) is 50000.

[0027] The beneficial effects of this invention are as follows: This invention provides a method for preparing high-specific-capacity silicon-carbon anode materials. By introducing modified porous carbon and combining electrospinning technology with multi-level structural design, the electrochemical performance of the silicon-carbon anode material is significantly improved. The modified porous carbon enhances the stability of the conductive network through the bridging effect of carboxylic acid-polyethylene glycol-carboxylic acid. Simultaneously, through supercritical reaction and carbonization treatment, a porous structure and a dense graphitized layer are constructed, improving the electron and ion transport efficiency and effectively buffering the volume expansion of silicon particles.

[0028] The ferric nitrate of this invention acts as a catalyst during calcination, further optimizing the electron transport performance of the conductive network. The axial conductive channels formed by electrospinning significantly improve the structural stability of the material. Test results show that the silicon-carbon anode material prepared by this invention exhibits an initial discharge capacity of up to 2052 mAh / g, a 2000-cycle capacity retention of 92.5%, and a volume expansion rate of only 12.4%, demonstrating excellent cycle stability and volume stability, making it suitable for high-energy-density lithium-ion batteries. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0030] In the specific embodiments of this invention, the porous carbon was purchased from Fujian Xinsen Carbon Industry Co., Ltd., model JK-03S; the carboxylic acid-polyethylene glycol-carboxylic acid was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number P136309, Mn is 600; the nano silica powder was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number S130843, particle size is 20-60nm; and the polyacrylonitrile was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number P303199, Mw is 50000.

[0031] Example 1:

[0032] (1) Add 20g of ammonium persulfate to 80g of sulfuric acid aqueous solution (2mol / L), stir for 20min, then add 0.8g of porous carbon, stir at 55℃ for 4h, wash, and dry to obtain carboxylated porous carbon;

[0033] (2) 0.6g of carboxylated multi-walled porous carbon and 0.2g of carboxylic acid-polyethylene glycol-carboxylic acid were dispersed together in 150mL of activation solution containing 0.1M EDC and 0.05M NHS (pH=5.5, phosphate buffer system), and ultrasonically treated for 1h. Then, 0.1g of triethylenetetramine was added, and the mixture was stirred at 55℃ for 5h under nitrogen protection. After centrifugation, washing, and drying, modified porous carbon was obtained.

[0034] (3) Add 1.5g of modified porous carbon and 0.1g of Fe(NO3)3·9H2O to 98.4g of ethanol / water solvent (volume ratio 2:1), and sonicate for 1h to obtain a dispersion;

[0035] (4) 10g of nano-silicon powder and 80g of dispersion were put into a supercritical reactor, the CO2 pressure was set to 15MPa, the temperature was 45℃, and the mixture was stirred at 200rpm for 3h. Then the mixture was put into a centrifugal spray dryer, the inlet temperature was set to 180℃, the outlet temperature was set to 70℃, and the atomizing disc speed was set to 15000rpm to obtain silicon composite.

[0036] (5) Add 10g of silicon composite to 50g of 5wt% polyacrylonitrile / DMF solution. Use an electrospinning machine with a voltage of 16kV, a receiving distance of 14cm, and a spinning rate of 1mL / h. After spinning, heat the solution in a tube furnace to 250℃ at 0.5℃ / min and keep it at that temperature for 0.5h. Then heat the solution from 250℃ to 550℃ at 1.5℃ / min and introduce C2H2 / Ar (volume ratio 1:15) for 2h. Then heat the solution to 820℃ at 2.5℃ / min and switch to H2 / CH4 (1:9) for 1h. Cool the solution to room temperature and grind it through a 200-mesh sieve to obtain a silicon-carbon anode material with high specific capacity.

[0037] Example 2:

[0038] (1) Add 24g of ammonium persulfate to 100g of sulfuric acid aqueous solution (2mol / L), stir for 30min, then add 1g of porous carbon, stir at 60℃ for 5h, wash, dry, and obtain carboxylated porous carbon;

[0039] (2) 0.8g of carboxylated multi-walled porous carbon and 0.4g of carboxylic acid-polyethylene glycol-carboxylic acid were dispersed together in 200mL of activation solution containing 0.1M EDC and 0.05M NHS (pH=5.5, phosphate buffer system), and ultrasonically treated for 2h. Then, 0.15g of triethylenetetramine was added, and the mixture was stirred at 60℃ for 6h under nitrogen protection. After centrifugation, washing, and drying, modified porous carbon was obtained.

[0040] (3) Add 2g of modified porous carbon and 0.5g of Fe(NO3)3·9H2O to 97.5g of ethanol / water solvent (volume ratio 3:1), and sonicate for 2h to obtain a dispersion;

[0041] (4) 10g of nano-silicon powder and 100g of dispersion were put into a supercritical reactor, the CO2 pressure was set to 20MPa, the temperature to 50℃, and the mixture was stirred at 300rpm for 4h. Then the mixture was put into a centrifugal spray dryer, the inlet temperature was set to 200℃, the outlet temperature to 80℃, and the atomizing disc speed to 18000rpm to obtain silicon composite.

[0042] (5) Add 10g of silicon composite to 50g of 8wt% polyacrylonitrile / DMF solution. Use an electrospinning machine with a voltage of 18kV, a receiving distance of 15cm, and a spinning rate of 1.2mL / h. After spinning, heat the solution in a tube furnace to 280℃ at 1℃ / min and keep it at that temperature for 1h. Then heat the solution from 280℃ to 600℃ at 2℃ / min and introduce C2H2 / Ar (volume ratio 1:15) for 3h. Then heat the solution to 850℃ at 3℃ / min and switch to H2 / CH4 (1:9) for 2h. Cool the solution to room temperature and grind it through a 200-mesh sieve to obtain a high specific capacity silicon-carbon anode material.

[0043] Example 3:

[0044] (1) Add 30g of ammonium persulfate to 120g of sulfuric acid aqueous solution (2mol / L), stir for 40min, then add 1.2g of porous carbon, stir at 65℃ for 6h, wash, and dry to obtain carboxylated porous carbon;

[0045] (2) 1g of carboxylated multi-walled porous carbon and 0.6g of carboxylic acid-polyethylene glycol-carboxylic acid were dispersed together in 250mL of activation solution containing 0.1M EDC and 0.05M NHS (pH=5.5, phosphate buffer system), and ultrasonically treated for 3h. Then, 0.2g of triethylenetetramine was added, and the mixture was stirred at 65℃ for 7h under nitrogen protection. After centrifugation, washing, and drying, the modified porous carbon was obtained.

[0046] (3) Add 2.5g of modified porous carbon and 1g of Fe(NO3)3·9H2O to 96.5g of ethanol / water solvent (volume ratio 4:1), and sonicate for 3h to obtain a dispersion;

[0047] (4) 10g of nano-silicon powder and 120g of dispersion were put into a supercritical reactor, the CO2 pressure was set to 25MPa, the temperature to 55℃, and the mixture was stirred at 400rpm for 5h. Then the mixture was put into a centrifugal spray dryer, the inlet temperature was set to 220℃, the outlet temperature to 90℃, and the atomizing disc speed to 20000rpm to obtain silicon composite.

[0048] (5) Add 10g of silicon composite to 50g of 10wt% polyacrylonitrile / DMF solution, use an electrospinning machine with a voltage of 20kV, a receiving distance of 16cm, and a spinning rate of 1.5mL / h. After spinning, heat the solution in a tube furnace to 300℃ at 1.5℃ / min and keep it at that temperature for 1.5h. Then heat the solution from 300℃ to 650℃ at 2.5℃ / min and introduce C2H2 / Ar (volume ratio 1:15) for 4h. Then heat the solution to 870℃ at 3.5℃ / min and switch to H2 / CH4 (1:9) for 3h. Cool the solution to room temperature and grind it through a 200-mesh sieve to obtain a silicon-carbon anode material with high specific capacity.

[0049] Comparative Example 1:

[0050] The difference between Comparative Example 1 and Example 2 is that the modified porous carbon in step (3) is replaced with carboxylated multi-walled porous carbon;

[0051] Comparative Example 2:

[0052] The difference between Comparative Example 2 and Example 2 is that carboxylic acid-polyethylene glycol-carboxylic acid was not added in step (2);

[0053] Comparative Example 3:

[0054] The difference between Comparative Example 3 and Example 2 is that Fe(NO3)3·9H2O was not added in step (3);

[0055] Comparative Example 4:

[0056] The difference between Comparative Example 4 and Example 2 is that the silicon composite was directly calcined in a tube furnace;

[0057] Performance testing:

[0058] Battery preparation: Anode material, acetylene black, and PVDF binder were weighed at a mass ratio of 8:1:1. N-methylpyrrolidone was added to adjust the solid content to 45wt%. The mixture was then stirred at 2000 rpm for 30 min (vacuum degree -0.1 MPa) and coated onto a 10 μm copper foil, with the areal density controlled at 3.0 ± 0.2 mg / cm³. 2 Then, it is vacuum dried at 120℃ for 12h, punched into Φ14mm electrode sheets, and then assembled into a battery in a glove box. The electrolyte is 1mol / L LiPF6 (EC:DMC:EMC=1:1:1vol%), and the separator is Celgard 2400.

[0059] First charge and discharge: According to standard GB / T 33827-2017, the current density is 0.1C and the voltage range is 0.005-3.0V. The discharge capacity and coulombic efficiency of the third cycle were tested, and the results are shown in Table 1.

[0060] Cyclic stability: Constant current charge and discharge, current density of 0.5C, cycle number of 2000 cycles, capacity retention rate was calculated, and the results are shown in Table 1.

[0061] Volume expansion rate: Record the initial thickness of the electrode (average of three measurements), disassemble the battery after 200 cycles at 0.5C, clean the electrode with ethanol, measure the thickness after expansion, and calculate the volume expansion rate. The results are shown in Table 1.

[0062] Table 1 Performance Test Results

[0063]

[0064]

[0065] Data Analysis:

[0066] As can be seen from the data in Table 1 for Examples 1-3, the silicon-carbon anode materials of Examples 1-3 all exhibited high initial discharge capacity and good cycle stability. Among them, Example 2 showed the best performance, with an initial discharge capacity of 2052 mAh / g, a capacity retention rate of 92.5% after 2000 cycles, and a volume expansion rate of only 12.4%. This indicates that the material design of Example 2 effectively suppressed the volume expansion of silicon while improving specific capacity. Its excellent performance may be attributed to the introduction of modified porous carbon and the optimized design of the multi-level structure. The modified porous carbon enhances the stability of the conductive network through the bridging effect of carboxylic acid-polyethylene glycol-carboxylic acid. At the same time, through supercritical and carbonization, a porous structure and a dense graphitized layer are constructed, which not only improves the electron and ion transport efficiency but also buffers the volume change of silicon. This multi-level structural design significantly reduces the volume expansion rate and improves cycle stability and coulombic efficiency, making it promising for high-energy-density lithium-ion batteries.

[0067] As can be seen from the data in Table 1 for Example 2 and Comparative Example 1, compared with Comparative Example 1, Example 2 showed an increase of 329 mAh / g in initial discharge capacity, an increase in 2000-cycle capacity retention from 74.8% to 92.5%, and a decrease in volume expansion rate from 35.6% to 12.4%. This indicates that the introduction of modified porous carbon plays an important role in improving the performance of silicon-carbon anode materials. Comparative Example 1 did not use modified porous carbon, resulting in weak interfacial bonding between the porous carbon and silicon particles. During cycling, the conductive network was prone to breakage, and the volume expansion of silicon particles could not be effectively buffered, leading to rapid capacity decay and a significant increase in volume expansion rate. In contrast, Example 2, through the EDC / NHS activation system and the crosslinking effect of triethylenetetramine, enabled the carboxylated multi-walled porous carbon to form a stable chemical bond with carboxylic acid-polyethylene glycol-carboxylic acid, enhancing the dispersibility of the porous carbon and the interfacial bonding with silicon particles, thereby constructing a more stable conductive network and significantly improving cycle stability and volume stability.

[0068] As can be seen from the data in Table 1 for Example 2 and Comparative Example 2, compared with Comparative Example 2, Example 2 showed an increase of 207 mAh / g in initial discharge capacity, an increase in 2000-cycle capacity retention from 79.6% to 92.5%, and a decrease in volume expansion from 28.9% to 12.4%. This indicates that the introduction of carboxylic acid-polyethylene glycol-carboxylic acid played a key role in optimizing the performance of the silicon-carbon anode material. In Comparative Example 2, the absence of carboxylic acid-polyethylene glycol-carboxylic acid resulted in difficulty for polyacrylonitrile to penetrate the porous carbon surface network, thus hindering the formation of a stable conductive network.

[0069] As can be seen from the data in Table 1 for Example 2 and Comparative Example 3, compared with Comparative Example 3, Example 2 showed an increase of 156 mAh / g in the initial discharge capacity, an increase in the 2000-cycle capacity retention from 82.3% to 92.5%, and a decrease in the volume expansion rate from 25.1% to 12.4%. This indicates that the introduction of Fe(NO3)3·9H2O plays an important role in optimizing the performance of silicon-carbon anode materials. Comparative Example 3 did not add Fe(NO3)3·9H2O, resulting in a lack of Fe during the calcination process. 3+ Due to the catalytic effect, the electron transport efficiency of the conductive network is low, and the volume expansion of silicon particles also lacks an effective buffer space.

[0070] As can be seen from the data in Table 1 for Example 2 and Comparative Example 4, compared with Comparative Example 4, Example 2 showed an increase of 424 mAh / g in initial discharge capacity, an increase in 2000-cycle capacity retention from 62.4% to 92.5%, and a decrease in volume expansion rate from 48.7% to 12.4%. This indicates that electrospinning plays a crucial role in optimizing the performance of silicon-carbon anode materials. In Comparative Example 4, the silicon composite was directly calcined, resulting in a lack of axial conductive channels formed by electrospinning. The stability of the conductive network was poor, and the volume expansion of silicon particles could not be effectively buffered, leading to structural damage and rapid capacity decay during cycling.

[0071] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a high-specific-capacity silicon-carbon anode material, characterized in that, Includes the following steps: (1) Add ammonium persulfate to a sulfuric acid aqueous solution with a concentration of 2 mol / L, stir for 20-40 min, then add porous carbon, stir at 55-65℃ for 4-6 h, wash, and dry to obtain carboxylated porous carbon; (2) Carboxylated porous carbon and carboxylic acid-polyethylene glycol-carboxylic acid are dispersed together in an activation solution, ultrasonically treated for 1-3 hours, then triethylenetetramine is added, and under nitrogen protection, the mixture is stirred at 55-65℃ for 5-7 hours. After centrifugation, washing, and drying, modified porous carbon is obtained. (3) Add the modified porous carbon and Fe(NO3)3·9H2O to an ethanol / water solvent and sonicate for 1-3 hours to obtain a dispersion; (4) Add nano-silicon powder and dispersion into a supercritical reactor and stir at 200-400 rpm for 3-5 hours. Then put it into a centrifugal spray dryer to obtain silicon composite. (5) Add the silicon composite to the polyacrylonitrile / DMF solution, use an electrospinning machine with a voltage of 16-20kV, a receiving distance of 14-16cm, and a spinning rate of 1-1.5mL / h. After spinning, calcine in a tube furnace and grind through a 200-mesh sieve to obtain a silicon-carbon anode material with high specific capacity. In step (2), the ratio of carboxylated multi-walled porous carbon, carboxylic acid-polyethylene glycol-carboxylic acid, activation solution and triethylenetetramine is 0.6-1g:0.2g-0.6g:150mL-250mL:0.1g-0.2g; The ethanol / water solvent in step (3) contains 1.5wt%-2.5wt% modified porous carbon and 0.1wt%-1wt% Fe(NO3)3·9H2O; In step (4), the weight ratio of nano-silicon powder to dispersion is 10:80-120; In step (5), the weight ratio of silicon composite and polyacrylonitrile / DMF solution is 1:

5. The polyacrylonitrile concentration in the polyacrylonitrile / DMF solution in step (5) is 5wt%-10wt%.

2. The method for preparing the high specific capacity silicon-carbon anode material according to claim 1, characterized in that, In step (1), the weight ratio of ammonium persulfate, sulfuric acid aqueous solution and porous carbon is 20-30:80-120:0.8-1.

2.

3. The method for preparing the high specific capacity silicon-carbon anode material according to claim 1, characterized in that, In step (2), the Mn of carboxylic acid-polyethylene glycol-carboxylic acid is 600.

4. The method for preparing the high specific capacity silicon-carbon anode material according to claim 1, characterized in that, In step (2), the activation solution is a phosphate buffer system containing 0.1M EDC and 0.05M NHS, with a pH of 5.

5.

5. The method for preparing the high specific capacity silicon-carbon anode material according to claim 1, characterized in that, In step (3), the volume ratio of ethanol to water in the ethanol / water solvent is 2-4:

1.

6. The method for preparing the high specific capacity silicon-carbon anode material according to claim 1, characterized in that, The particle size of the nano-silicon powder in step (4) is 20-60 nm.

7. The method for preparing the high specific capacity silicon-carbon anode material according to claim 1, characterized in that, In step (4), the CO2 pressure of the supercritical reactor is 15-25 MPa, the temperature is 45-55℃, the inlet temperature of the centrifugal spray dryer is 180-220℃, the outlet temperature is 70-90℃, and the atomizing disc speed is 15000-20000 rpm.

8. The method for preparing the high specific capacity silicon-carbon anode material according to claim 1, characterized in that, In step (5), the voltage of the electrospinning machine is 16-20kV, the receiving distance is 14-16cm, and the spinning rate is 1-1.5mL / h.

9. The method for preparing the high specific capacity silicon-carbon anode material according to claim 1, characterized in that, The calcination process in step (5) is as follows: the temperature is increased to 250-300℃ at 0.5-1.5℃ / min and held for 0.5-1.5h, then increased from 250-300℃ to 550-650℃ at 1.5-2.5℃ / min, and C2H2 / Ar is introduced for 2-4h, then increased to 820-870℃ at 2.5-3.5℃ / min, and H2 / CH4 is introduced for 1-3h, and then cooled to room temperature.

10. The method for preparing the high specific capacity silicon-carbon anode material according to claim 1, characterized in that, In step (5), the Mw of polyacrylonitrile is 50000.

Images