Silicon-carbon negative electrode material, preparation method and application thereof
Copper-doped silicon-carbon anode materials were prepared by self-assembly and pyrolysis of modified microcrystalline graphite and silicon waste, solving the problems of conductivity and cycle stability of silicon anode materials and realizing the low-cost and high-efficiency production of silicon-carbon composite materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- KUNMING UNIV OF SCI & TECH
- Filing Date
- 2024-07-11
- Publication Date
- 2026-04-28
AI Technical Summary
Silicon anode materials suffer from problems such as rapid capacity decay, large volume expansion, low conductivity, and slow ion diffusion during use. Furthermore, the preparation of silicon-carbon composite materials is complex and costly.
Modified microcrystalline graphite was obtained by mixing copper salt, water, and microcrystalline graphite dispersion with a precipitant. Then, it was mixed with silicon waste and a carbon source for self-assembly to form copper-doped silicon-carbon microspheres. Finally, silicon-carbon anode material was obtained by pyrolysis treatment.
The conductivity and cycle stability of silicon anode materials were improved, production costs were reduced, and volume expansion of silicon was suppressed through particle size improvement and carbon coating strategies, thereby improving the tap density and cycle performance of the materials.
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Figure CN118754115B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery anode technology, and in particular to a silicon-carbon anode material, its preparation method, and its application. Background Technology
[0002] Silicon has an extremely high theoretical specific capacity and is often regarded as a promising high specific capacity anode material. However, during use, silicon exhibits rapid capacity decay and suffers from problems such as large volume expansion, low conductivity, and slow ion diffusion.
[0003] Currently, the performance of silicon anode materials is often improved through nano-sizing, combining silicon with metals, and compositing with active or inactive materials. Among these methods, silicon-carbon composite materials are the main technological approach. However, the preparation of silicon-carbon materials is complex, resulting in poor cycle life and high cost. Summary of the Invention
[0004] The purpose of this invention is to provide a silicon-carbon anode material, its preparation method, and its application, thereby reducing production costs and improving the conductivity and cycle stability of silicon anode materials.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] A method for preparing a silicon-carbon anode material includes the following steps:
[0007] 1) Mix copper salt, water, microcrystalline graphite dispersion and precipitant, and modify them to obtain modified microcrystalline graphite;
[0008] 2) The modified microcrystalline graphite, silicon waste and carbon source are mixed and self-assembled to obtain copper-doped silicon-carbon microspheres;
[0009] 3) The copper-doped silicon-carbon microspheres are pyrolyzed to obtain the silicon-carbon anode material.
[0010] Optionally, the copper salt in step 1) comprises at least one of Cu(NO3)2·3H2O, CuSO4·5H2O, or CuCl2.
[0011] Optionally, the precipitant in step 1) comprises at least one of NH4HCO3, NaOH, NaCO3 or HCl; the mass ratio of microcrystalline graphite and precipitant in the copper salt, water, and microcrystalline graphite dispersion is 1-3:8-20:2-4:1-3.
[0012] Optionally, the modification temperature in step 1) is 50–100°C, and the time is 30–120 min.
[0013] Optionally, the concentration of silicon waste in the silicon waste suspension in step 2) is 0.02-0.3 g / mL; the carbon source includes at least one of nanocellulose, carbon nanotubes, sucrose, glucose, dopamine or pitch; the mass ratio of modified microcrystalline graphite, silicon waste and carbon source in the silicon waste suspension is 1-5:1-6:0.2-1.5.
[0014] Optionally, the self-assembly temperature in step 2) is 100–200°C.
[0015] Optionally, the pyrolysis temperature in step 3) is 700–3000℃; the pyrolysis time is 0.1–12 h.
[0016] The present invention provides a silicon-carbon anode material prepared by the aforementioned method.
[0017] The present invention also provides the application of the silicon-carbon anode material in lithium-ion batteries.
[0018] This invention provides a method for preparing a silicon-carbon anode material. Specifically, based on the structural characteristics of microcrystalline graphite and silicon waste, the microcrystalline graphite and waste silicon are first physically crushed to improve particle size. Reduced particle size effectively alleviates the volume expansion of silicon and enhances the composite material between silicon and microcrystalline graphite. Subsequently, a layer of copper is deposited on the surface of the microcrystalline graphite using chemical deposition to modify its surface. The acid-base neutralization reaction of copper deposits a copper compound on the surface of the microcrystalline graphite, which not only improves the surface defects of the microcrystalline graphite itself, but also enhances the conductivity and tap density of the silicon composite material due to the excellent conductivity and high relative atomic mass of copper. Finally, the modified microcrystalline graphite and waste silicon powder are subjected to controlled spray granulation and carbon coating treatment, followed by high-temperature pyrolysis to obtain the silicon-carbon anode material of this invention.
[0019] In the silicon-carbon anode material of the present invention, silicon particles are attached to the surface of modified microcrystalline graphite and coated by a carbon source. The effective composite of silicon and graphite can not only reduce unnecessary electrolyte decomposition on the electrode surface, but also help maintain good electrode integrity during cycling. This gives the material high initial coulombic efficiency and high cycle performance, and can significantly slow down the self-generated volume expansion of silicon material during charging and discharging, thereby improving the cycle stability of the battery.
[0020] The improved particle size and carbon coating strategy in this invention can effectively suppress the volume expansion of silicon, reduce the side reactions between silicon and electrolyte, improve the first coulombic efficiency and cycle stability of the composite material, and the quality improvement brought by copper doping and the refinement of material particle size together improve the tap density of the composite material.
[0021] This invention has low requirements for raw materials, simple equipment requirements, and is easy to operate and scale up. The waste silicon and microcrystalline graphite used are inexpensive, enabling low-cost continuous industrial production. It can effectively recycle crystalline silicon waste from the photovoltaic industry and can also effectively prepare high-efficiency, high-tap-density spherical silicon-carbon anode materials, providing a potential solution for the large-scale production of silicon-based anode materials. Attached Figure Description
[0022] Figure 1 This is a flowchart illustrating the preparation method of the silicon-carbon anode material described in this invention.
[0023] Figure 2 The image shows the morphology of the silicon-carbon anode material prepared in Example 1.
[0024] Figure 3 The image shows the morphology of the silicon-carbon anode material prepared in Example 2.
[0025] Figure 4 The image shows the morphology of the silicon-carbon anode material prepared in Example 3.
[0026] Figure 5 The image shows the morphology of the silicon-carbon anode material prepared in Example 4.
[0027] Figure 6 The image shows the morphology of the silicon-carbon anode material prepared in Example 5, along with its cycling performance. Detailed Implementation
[0028] like Figure 1 As shown, the present invention provides a method for preparing a silicon-carbon anode material, comprising the following steps:
[0029] 1) Mix copper salt, water, microcrystalline graphite dispersion and precipitant, and modify them to obtain modified microcrystalline graphite;
[0030] 2) The modified microcrystalline graphite, silicon waste suspension and carbon source are mixed and self-assembled to obtain copper-doped silicon-carbon microspheres;
[0031] 3) The copper-doped silicon-carbon microspheres are pyrolyzed to obtain the silicon-carbon anode material.
[0032] In this invention, the microcrystalline graphite in step 1) is preferably refined by grinding; the particle size of the refined microcrystalline graphite is preferably 0.05-5 μm, more preferably 0.1-4.5 μm;
[0033] The grinding process preferably uses a crusher and a sand mill in sequence. The crusher's operating conditions are not specifically limited, as long as it can perform the crushing task. The preferred speed of the sand mill is 2000–2800 r / min, more preferably 2100–2500 r / min, and even more preferably 2200–2400 r / min. The preferred grinding time is 2–12 hours, more preferably 3–10 hours, more preferably 4–8 hours, and even more preferably 5–6 hours. The preferred grinding medium is water, an aqueous solution, or an alcohol solution, more preferably anhydrous ethanol.
[0034] The refined microcrystalline graphite is dried and dispersed in water to obtain a microcrystalline graphite dispersion.
[0035] The drying conditions are not specifically limited, and any conditions that can complete the drying process are acceptable. The concentration of the microcrystalline graphite dispersion is preferably 0.25–0.5 g / mL.
[0036] In this invention, the copper salt in step 1) preferably contains at least one of Cu(NO3)2·3H2O, CuSO4·5H2O or CuCl2.
[0037] In this invention, the precipitant in step 1) preferably contains at least one of NH4HCO3, NaOH, NaCO3, or HCl; the mass ratio of the copper salt, water, microcrystalline graphite dispersion, and precipitant is preferably 1-3:8-20:2-4:1-3, more preferably 1-2:8-15:2-3:1-2, and even more preferably 1-2:10-12:2-3:1-2.
[0038] In this invention, the temperature for modification in step 1) is preferably 50-100°C, more preferably 60-90°C, and even more preferably 70-80°C; the time is preferably 30-120 min, and more preferably 60-90 min.
[0039] In this invention, the mixing in step 1) is preferably performed by mixing copper salt with water, then adding the microcrystalline graphite dispersion, heating, and when the temperature reaches 100°C, adding a precipitant solution dropwise.
[0040] Step 1) After the precipitant solution is added dropwise, the mixture is stirred at a constant temperature to allow it to react fully. After the reaction is complete, the mixture is filtered and washed multiple times with deionized water to obtain modified microcrystalline graphite.
[0041] In this invention, the silicon waste mentioned in step 2) preferably includes silicon cutting waste from photovoltaic solar cells;
[0042] The silicon waste suspension is preferably refined by sand milling, and the refined silicon waste suspension is obtained with anhydrous ethanol as the medium; the particle size of the refined silicon waste is preferably 0.05-5μm, more preferably 0.1-4.5μm; the particle size of the refined microcrystalline graphite is preferably 0.05-5μm, more preferably 0.1-4.5μm;
[0043] The grinding process preferably uses a crusher and a sand mill in sequence. The crusher is not subject to any special conditions and can be used as long as it can complete the crushing process. The preferred speed of the sand mill is 2000-2800 r / min, more preferably 2100-2500 r / min, and even more preferably 2200-2400 r / min. The preferred grinding time is 2-12 h, more preferably 3-10 h, more preferably 4-8 h, and even more preferably 5-6 h. The preferred grinding medium is water, an aqueous solution, or an alcohol solution, and more preferably anhydrous ethanol.
[0044] In this invention, the concentration of silicon waste in the silicon waste suspension in step 2) is preferably 0.02-0.3 g / mL, more preferably 0.025-0.1 g / mL, and even more preferably 0.035-0.04 g / mL; the carbon source preferably includes at least one of nanocellulose, carbon nanotubes, sucrose, glucose, dopamine, or pitch. When the carbon source is two or more of the above, the ratio between the carbon sources can be adjusted according to the actual situation; the mass ratio of silicon waste and carbon source in the modified microcrystalline graphite, silicon waste suspension is preferably 1-5:1-6:0.2-1.5, more preferably 1-4:1.2-4:0.25-1, and even more preferably 2-3:2-3:0.3-0.6.
[0045] In this invention, the self-assembly temperature in step 2) is preferably 100-200°C, more preferably 110-150°C, and even more preferably 120-130°C.
[0046] In this invention, the feed rate of the precursor solution in step 2) of the self-assembly process is preferably 0.1-33 mL / min, more preferably 5-15 mL / min, and even more preferably 8-10 mL / min; the assembly process preferably requires the introduction of gas, which is preferably at least one of nitrogen, argon, or air; the gas inlet rate is preferably 0.1-100 mL / min, more preferably 5-15 mL / min, and even more preferably 8-10 mL / min.
[0047] In this invention, the pyrolysis temperature in step 3) is preferably 700–3000°C, more preferably 800–1500°C, and even more preferably 1000–1300°C; the pyrolysis time is preferably 0.1–12 h, more preferably 2–8 h, and even more preferably 4–6 h.
[0048] In this invention, the pyrolysis in step 3) preferably involves the introduction of argon gas, with a flow rate preferably of 5-20 mL / min, more preferably of 10-15 mL / min; the heating rate of the pyrolysis is preferably 0.1-20 °C / min, more preferably of 3-15 °C / min, and even more preferably of 5-10 °C / min.
[0049] The present invention provides a silicon-carbon anode material prepared by the aforementioned method.
[0050] This invention also provides the application of the silicon-carbon anode material in lithium-ion batteries; this invention does not specifically limit the method of application, and any method that can be used in lithium-ion batteries is acceptable.
[0051] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0052] Example 1
[0053] (1) The waste silicon material and microcrystalline graphite raw materials were refined by crushing and then further ground to the submicron level by sand mill. Anhydrous ethanol was used as the grinding medium for sand milling. The speed of sand milling was controlled at 2800 r / min and the sand milling time was controlled at 3 h. The particle size distribution of the refined waste silicon material and microcrystalline graphite was 0.05~5μm. After the waste silicon material was sand milled, a silicon waste suspension was obtained with a concentration of 0.04 g / mL.
[0054] (2) After the sand-milled microcrystalline graphite was dried in a vacuum drying oven at 60℃, 100g of the graphite was dispersed in 200mL of deionized water to obtain a microcrystalline graphite dispersion of 0.5g / mL.
[0055] 25g Cu(NO3)2·3H2O and 200mL deionized water were mixed in a beaker and magnetically stirred for 15min. Then, 100mL of the microcrystalline graphite dispersion (0.5g / mL) was added and stirred until homogeneous. The mixture was then heated. When the temperature reached 100℃, 500mL of NH4HCO3 solution (0.05g / mL) was added dropwise. After the addition was complete, the mixture was stirred at a constant temperature for 60min to allow the reaction to proceed. After the reaction was complete, the mixture was filtered and washed with deionized water to obtain modified microcrystalline graphite.
[0056] (3) Take 19.2g of the modified microcrystalline graphite obtained in step (2), 600mL of the refined silicon waste suspension (0.04g / mL) obtained in step (1), and mix it with 2.4g of pitch and 2.4g of nanocellulose to obtain a precursor solution;
[0057] The precursor solution was added at a feed rate of 10 mL / min, and nitrogen gas was introduced at an inlet rate of 10 mL / min. Spray granulation and self-assembly were carried out in a spray granulator at 150 °C for 1 h to obtain copper-doped silicon-carbon microspheres.
[0058] (4) Place the copper-doped silicon-carbon microspheres obtained in step (3) in a tube furnace, introduce argon gas at a flow rate of 10 mL / min, and then heat to 700℃ for 2 hours at a heating rate of 5℃ / min to obtain silicon-carbon anode material.
[0059] Example 2
[0060] (1) The waste silicon material and microcrystalline graphite raw materials were refined by crushing, and then further ground to the submicron level by sand mill. Anhydrous ethanol was used as the grinding medium for sand milling. The speed of sand milling was controlled at 2400 r / min and the sand milling time was controlled at 8 h. The particle size distribution of the refined waste silicon material and microcrystalline graphite was 0.05~5μm. After the waste silicon material was sand milled, a silicon waste suspension was obtained with a concentration of 0.1g / mL.
[0061] (2) After the sand-milled microcrystalline graphite was dried in a vacuum drying oven at 60℃, 100g of the graphite was dispersed in 200mL of deionized water to obtain a microcrystalline graphite dispersion of 0.5g / mL.
[0062] 12g Cu(NO3)2·3H2O and 96mL deionized water were mixed in a beaker and stirred magnetically for 15min. Then, 48mL of the microcrystalline graphite dispersion (0.5g / mL) was added and stirred until homogeneous. The mixture was then heated. When the temperature reached 100℃, 100mL of NH4HCO3 solution (0.12g / mL) was added dropwise. After the addition was complete, the mixture was stirred at a constant temperature for 60min to allow the reaction to proceed. After the reaction was complete, the mixture was filtered and washed with deionized water to obtain modified microcrystalline graphite.
[0063] (3) Take 12g of the modified microcrystalline graphite obtained in step (2), 240mL of the refined silicon waste suspension (0.1g / mL) obtained in step (1), and mix it with 0.8g of pitch and 3.2g of nanocellulose to obtain a precursor solution;
[0064] The precursor solution was added at a feed rate of 8 mL / min, and nitrogen gas was introduced at an inlet rate of 5 mL / min. The mixture was then spray-granulated and self-assembled in a spray granulator at 120 °C for 30 min to obtain copper-doped silicon-carbon microspheres.
[0065] (4) Place the copper-doped silicon-carbon microspheres obtained in step (3) in a tube furnace, introduce argon gas at a flow rate of 15 mL / min, and then heat to 1300℃ for 4 hours at a heating rate of 10℃ / min to obtain silicon-carbon anode material.
[0066] Example 3
[0067] (1) The waste silicon material and microcrystalline graphite raw materials were refined by crushing and then further ground to submicron level by sand mill. Anhydrous ethanol was used as the grinding medium for sand milling. The speed of sand mill was controlled at 2000 r / min and the sand milling time was controlled at 10 h. The particle size distribution of the refined waste silicon material and microcrystalline graphite was 0.05~5μm. After the waste silicon material was sand milled, a silicon waste suspension was obtained with a concentration of 0.025g / mL.
[0068] (2) After the sand-milled microcrystalline graphite was dried in a vacuum drying oven at 60℃, 100g of the graphite was dispersed in 400mL of deionized water to obtain a microcrystalline graphite dispersion of 0.25g / mL.
[0069] 24g CuSO4·5H2O and 192mL deionized water were mixed in a beaker and stirred magnetically for 15min. The 192mL microcrystalline graphite dispersion (0.25g / mL) was then added and stirred until homogeneous. The mixture was then heated. When the temperature reached 100℃, 60mL NaOH solution (40% by mass) was added dropwise. After the addition was complete, the mixture was stirred at a constant temperature for 60min to allow the reaction to proceed. After the reaction was complete, the mixture was filtered and washed with deionized water to obtain modified microcrystalline graphite.
[0070] (3) Mix 16g of modified microcrystalline graphite obtained in step (2), 800mL of refined silicon waste suspension (0.025g / mL) obtained in step (1) with 4g of pitch to obtain a precursor solution;
[0071] The precursor solution was added at a feed rate of 15 mL / min, and nitrogen gas was introduced at an inlet rate of 10 mL / min. The mixture was then spray-granulated and self-assembled in a spray granulator at 130 °C for 80 min to obtain copper-doped silicon-carbon microspheres.
[0072] (4) Place the copper-doped silicon-carbon microspheres obtained in step (3) in a tube furnace, introduce argon gas at a flow rate of 5 mL / min, and then heat to 1300℃ for 4 hours at a heating rate of 10℃ / min to obtain silicon-carbon anode material.
[0073] Example 4
[0074] (1) The waste silicon material and microcrystalline graphite raw materials were refined by crushing and then further ground to the submicron level by sand mill. Anhydrous ethanol was used as the grinding medium for sand milling. The speed of sand milling was controlled at 2500 r / min and the sand milling time was controlled at 6 h. The particle size distribution of the refined waste silicon material and microcrystalline graphite was 0.05~5μm. After the waste silicon material was sand milled, a silicon waste suspension was obtained with a concentration of 0.035 g / mL.
[0075] (2) After the sand-milled microcrystalline graphite was dried in a vacuum drying oven at 60℃, 150g of it was dispersed in 300mL of deionized water to obtain a microcrystalline graphite dispersion of 0.5g / mL.
[0076] 12g CuSO4·5H2O and 96mL deionized water were mixed in a beaker and magnetically stirred for 15min. Then, 48mL of the microcrystalline graphite dispersion (0.5g / mL) was added and stirred until homogeneous. The mixture was then heated. When the temperature reached 100℃, 60mL of NaOH solution (20% concentration) was added dropwise. After the addition was complete, the mixture was stirred at a constant temperature for 60min to allow the reaction to proceed. After the reaction was complete, the mixture was filtered and washed with deionized water to obtain modified microcrystalline graphite.
[0077] (3) Mix 21g of modified microcrystalline graphite obtained in step (2), 1000mL of refined silicon waste suspension (0.035g / mL) obtained in step (1), 3.5g of pitch and 3.5g of nanocellulose to obtain a precursor solution;
[0078] The precursor solution was added at a feed rate of 8 mL / min, and nitrogen gas was introduced at an inlet rate of 8 mL / min. Spray granulation and self-assembly were carried out in a spray granulator at 110 °C for 100 min to obtain copper-doped silicon-carbon microspheres.
[0079] (4) Place the copper-doped silicon-carbon microspheres obtained in step (3) in a tube furnace, introduce argon gas at a flow rate of 15 mL / min, and then heat to 1000℃ for 8 hours at a heating rate of 5℃ / min to obtain silicon-carbon anode material.
[0080] Example 5
[0081] (1) The waste silicon material and microcrystalline graphite raw materials were refined by crushing and then further ground to submicron level by sand mill. Anhydrous ethanol was used as the grinding medium for sand milling. The speed of sand mill was controlled at 2500 r / min and the sand milling time was controlled at 4 h. The particle size distribution of the refined waste silicon material and microcrystalline graphite was 0.05~5μm. After the waste silicon material was sand milled, a silicon waste suspension was obtained with a concentration of 0.05g / mL.
[0082] (2) After the sand-milled microcrystalline graphite was dried in a vacuum drying oven at 60℃, 100g of the graphite was dispersed in 200mL of deionized water to obtain a microcrystalline graphite dispersion of 0.5g / mL.
[0083] 12g Cu(NO3)2·3H2O and 200mL deionized water were mixed in a beaker and magnetically stirred for 15min. Then, 100mL of the microcrystalline graphite dispersion (0.5g / mL) was added and stirred until homogeneous. The mixture was then heated. When the temperature reached 100℃, 100mL of NH4HCO3 solution (concentration 4.8g / L) was added dropwise. After the addition was completed, the mixture was stirred at a constant temperature for 60min to allow the reaction to proceed. After the reaction was completed, the mixture was filtered and washed with deionized water to obtain modified microcrystalline graphite.
[0084] (3) Mix 20g of modified microcrystalline graphite obtained in step (2), 500mL of refined silicon waste suspension (0.05g / mL) obtained in step (1), 1g of pitch and 4g of nanocellulose in a mass ratio of 4:5:0.2:0.8 to obtain a precursor solution;
[0085] The precursor solution was added at a feed rate of 10 mL / min, and nitrogen gas was introduced at an inlet rate of 15 mL / min. Spray granulation and self-assembly were carried out in a spray granulator at 130 °C for 50 min to obtain copper-doped silicon-carbon microspheres.
[0086] (4) Place the copper-doped silicon-carbon microspheres obtained in step (3) in a tube furnace, introduce argon gas at a flow rate of 15 mL / min, and then heat to 800℃ for 6 h at a heating rate of 3℃ / min to obtain silicon-carbon anode material.
[0087] Test case
[0088] The morphology of the silicon-carbon anode materials prepared in Examples 1-4 was examined using field emission scanning electron microscopy, and the results are as follows: Figures 1-4 As shown;
[0089] in, Figure 2 This is a morphology diagram of the silicon-carbon anode material prepared in Example 1;
[0090] pass Figure 2 It can be observed that the silicon-carbon anode material prepared in Example 1 has an overall spherical morphology, with a smooth surface and some individual spheres having defects.
[0091] Figure 3 This is a morphology diagram of the silicon-carbon anode material prepared in Example 2;
[0092] pass Figure 3 It can be observed that the silicon-carbon anode material prepared in Example 2 has high sphericity, uniform morphology, and smooth and dense surface.
[0093] Figure 4 This is a morphology diagram of the silicon-carbon anode material prepared in Example 3;
[0094] pass Figure 4 It can be observed that the silicon-carbon anode material prepared in Example 3 has high sphericity and a smooth surface;
[0095] Figure 5 This is a morphology diagram of the silicon-carbon anode material prepared in Example 4;
[0096] pass Figure 5 It can be observed that the silicon-carbon anode material prepared in Example 4 is basically spherical, with defects visible on the surface of a few spheres.
[0097] The tap density of the silicon-carbon anode materials prepared in Examples 1-5 was tested using a Yuntang YZ-ZS1 tap density meter. The silicon-carbon anode materials prepared in Examples 1-5 were then used for coin cell testing. Lithium foil was used as the electrode material, and the electrolyte was 1.5M LiTFSI in EC:DEC = 1:1 VO1% with 5.0% FEC. The testing system was a Xinwei battery testing system. The initial coulombic efficiency, initial discharge specific capacity, and charge-discharge cycle performance after 150 cycles were measured at 0.2 A / g. The results are shown in Table 1.
[0098] Table 1 Performance tests of silicon-carbon anode materials prepared in Examples 1-5
[0099]
[0100] The silicon-carbon anode material prepared in Example 5 was subjected to cycle performance testing, and the results are as follows: Figure 6 As shown;
[0101] pass Figure 6 It can be observed that the silicon-carbon anode material exhibits excellent cycle performance. When tested under a current density of 0.2 A / g, the initial discharge specific capacity is 2624 mAh / g, and after 150 charge-discharge cycles, the remaining capacity is 1592 mAh / g.
[0102] Through Table 1 and Figure 6 It can be observed that the tap density of the silicon-carbon anode material prepared by this invention can reach 0.91 g / cm³. 3 The initial coulombic efficiency can reach 89.8%, the initial discharge specific capacity is 2901mAh / g, and the remaining capacity after 150 charge-discharge cycles can reach 1825mAh / g, exhibiting good true density and cycle stability.
[0103] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a silicon-carbon anode material, characterized in that, Includes the following steps 1) Mix copper salt, water, microcrystalline graphite dispersion and precipitant, and modify them to obtain modified microcrystalline graphite; 2) The modified microcrystalline graphite, silicon waste suspension and carbon source are mixed and self-assembled to obtain copper-doped silicon-carbon microspheres; 3) The copper-doped silicon-carbon microspheres are pyrolyzed to obtain the silicon-carbon anode material; The mass ratio of silicon waste and carbon source in the modified microcrystalline graphite and silicon waste suspension is 1~5:1~6:0.2~1.5; Step 3) The pyrolysis temperature is 700~3000℃; the pyrolysis time is 0.1~12h.
2. The preparation method according to claim 1, characterized in that, Step 1) The copper salt contains at least one of Cu(NO3)2·3H2O, CuSO4·5H2O or CuCl2.
3. The preparation method according to claim 1 or 2, characterized in that, Step 1) The precipitant contains at least one of NH4HCO3, NaOH, NaCO3 or HCl; the mass ratio of microcrystalline graphite and precipitant in the copper salt, water, and microcrystalline graphite dispersion is 1~3:8~20:2~4:1~3.
4. The preparation method according to claim 3, characterized in that, Step 1) The modification temperature is 50~100℃ and the time is 30~120min.
5. The preparation method according to claim 1, characterized in that, Step 2) The concentration of silicon waste in the silicon waste suspension is 0.02~0.3g / mL; the carbon source includes at least one of nanocellulose, carbon nanotubes, sucrose, glucose, dopamine or pitch.
6. The preparation method according to claim 1, characterized in that, Step 2) The self-assembly temperature is 100~200℃.
7. The silicon-carbon anode material prepared by the preparation method according to any one of claims 1 to 6.
8. The application of the silicon-carbon anode material according to claim 7 in lithium-ion batteries.
Citation Information
Patent Citations
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