Silicon-carbon nanotube composites, methods of making, and applications
By covalently anchoring silicon particles to carbon nanotubes in lithium-ion batteries and using iminodiacetic acid as a bridge, the problems of poor dispersion and volume change of silicon particles in carbon materials are solved, thereby improving the stability and cycle performance of the electrode.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHENGDU ORGANIC CHEM CO LTD CHINESE ACAD OF SCI
- Filing Date
- 2023-03-27
- Publication Date
- 2026-07-03
AI Technical Summary
In existing lithium-ion batteries, silicon particles are poorly dispersed in carbon materials, carbon has insufficient charge transport capacity as a coating layer, and its mechanical rigidity is insufficient to buffer the volume changes of silicon particles during charging and discharging, resulting in unstable electrode structure.
Silicon particles are anchored to carbon nanotubes through covalent bonding, and iminodiacetic acid is used as a bridge to improve dispersibility and electron transport capabilities, while also buffering volume expansion forces and reducing electrode crack formation.
This improves the uniformity of silicon particle dispersion among carbon nanotubes, maintains conductive connections, reduces interfacial stress, prevents mechanical fracture, and improves the stability and cycle performance of the electrode structure.
Smart Images
Figure CN116314698B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery technology, and more specifically, to silicon-carbon nanotube composite materials, their preparation methods, and their applications. Background Technology
[0002] Lithium-ion batteries, with their advantages of light weight, high voltage, high specific energy, low self-discharge rate, good cycle performance, no memory effect, and environmental friendliness, are the most important and fastest-growing chemical energy storage power source in mobile communications, portable appliances, electric vehicles, and defense technology. With the rapid development of electronic information technology and power batteries, the demand for high-efficiency power sources has increased dramatically. Developing battery materials with larger capacity, higher power density, and longer cycle life has become the research goal for next-generation lithium-ion battery electrode materials.
[0003] Currently, the main anode materials for industrialized lithium-ion batteries are various carbon materials, including graphitized carbon materials and amorphous carbon materials, such as natural graphite, modified graphite, graphitized mesophase carbon microspheres, soft carbon (such as coke), and hard carbon materials. Due to the limitations of carbon materials, such as low specific capacity, low initial discharge efficiency, and inability to co-intercalate with organic solvents, researchers have begun developing other high-specific-capacity non-carbon anode materials while studying carbon materials. Among these, silicon has a relatively high theoretical specific capacity (4200 mAh / g, Li...). 22 Si (Si₅) is considered the most promising candidate to replace carbon anode materials as the next generation of high-performance lithium-ion battery anode materials. However, due to the large volume expansion of Si during charge and discharge, the instability of the SEI film, and the low electronic conductivity leading to a rapid capacity decline, researchers are currently working to improve the electrochemical performance of silicon materials by combining silicon with carbon. However, in practical applications, the poor dispersion of silicon particles in carbon materials, the charge transport capacity of carbon as a coating layer, and the mechanical rigidity of carbon materials make it difficult to buffer the volume changes of silicon particles during long-term cycling, thus limiting its practical application. Summary of the Invention
[0004] <Technical Problem Solved by the Invention>
[0005] This technology aims to address the problems of poor dispersion of silicon particles in carbon materials, the charge transport capacity of carbon as a coating layer, and the difficulty of the mechanical rigidity of carbon materials in buffering the volume changes of silicon particles during long-term cycling.
[0006] <Technical Solution Adopted in This Invention>
[0007] To address the aforementioned technical problems, the present invention aims to provide a silicon-carbon nanotube composite material, its preparation method, and its applications. The silicon-carbon nanotube composite material provided by this invention anchors silicon particles to carbon nanotubes through covalent bonds. This not only increases the uniformity of dispersion of carbon nanotubes and silicon particles and improves electron transport capability, but also provides a certain counterforce to the volume expansion force of silicon particles, reducing electrode cracking and thus reducing electrolyte consumption and improving the overall cycle stability of the electrode. Furthermore, the preparation method provided by this invention requires no complex operating procedures, has simple process requirements, and is suitable for large-scale production.
[0008] The details are as follows:
[0009] First, the present invention provides a silicon-carbon nanotube composite material, which is obtained by dehydration of hydroxylated silicon particles, hydroxylated carbon nanotubes and iminodiacetic acid.
[0010] Second, the present invention provides a method for preparing the aforementioned silicon-carbon nanotube composite material, comprising the following steps:
[0011] An aqueous dispersion of iminodiacetic acid was formed, and then hydroxylated silicon particles and hydroxylated carbon nanotubes were added and blended to obtain a blend.
[0012] The blend was subjected to hydrothermal treatment to obtain a silicon-carbon nanotube composite material.
[0013] Third, the present invention relates to the application of the aforementioned silicon-carbon nanotube composite material in the negative electrode of a lithium-ion battery.
[0014] <Beneficial effects achieved by the present invention>
[0015] (1) The silicon-carbon nanotube composite material of the present invention improves the uniformity of carbon nanotube dispersion among silicon particles, thereby improving the electron transport rate of the active material.
[0016] (2) This invention anchors silicon particles to the surface of carbon nanotubes through a co-crosslinking reaction of iminodiacetic acid, achieving a lasting contact between the silicon particles and carbon nanotubes and maintaining a conductive connection. At the same time, due to the buffering effect of the iminodiacetic acid layer on the surface of the silicon particles, the interfacial stress of the silicon particles during the charging and discharging process is reduced, alleviating silicon particle pulverization.
[0017] (3) In this invention, iminodiacetic acid acts as a bridge between silicon particles and carbon nanotubes, promoting electron / ion transfer while preventing mechanical breakage during cycling, thereby ensuring the stability of the entire electrode structure and improving the cycling performance of the material. Attached Figure Description
[0018] Figure 1The image shows a SEM image of the iminodiacetic acid covalently crosslinked silicon / carbon nanotube composite material prepared in Example 2.
[0019] Figure 2 The cyclic voltammogram of the iminodiacetic acid covalently crosslinked silicon / carbon nanotube composite material prepared in Example 2 is shown below.
[0020] Figure 3 Cyclic performance test diagram of coin cell fabricated from iminodiacetic acid covalently crosslinked silicon / carbon nanotube composite material prepared in Example 2. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0022] <Technical Solution>
[0023] First, this invention provides a silicon-carbon nanotube composite material, obtained by dehydrating hydroxylated silicon particles, hydroxylated carbon nanotubes, and iminodiacetic acid. Specifically, the hydroxylated silicon particles / hydroxylated carbon nanotubes are obtained by dehydration condensation with the carboxyl groups in iminodiacetic acid, such that the silicon particles with Si-O bonds are anchored to the carbon nanotubes with CO bonds via iminodiacetic acid.
[0024] Further, the mass ratio of iminodiacetic acid, hydroxylated carbon nanotubes, and hydroxylated silicon particles is 1–10:1–15:8–40. Preferably, the mass ratio of the first three is 1:1–4:20–40.
[0025] Furthermore, the particle size of the silicon particles ranges from 50 to 200 nm; the aspect ratio of the carbon nanotubes ranges from 0.2 to 15.
[0026] Furthermore, the method for preparing hydroxylated silicon particles involves treating the silicon particles in an oxidizing solution at a certain temperature.
[0027] The oxidizing solution is sulfuric acid (18 mol / L): H2O2 (6 mol / L) = 1~3:1~3 (V:V).
[0028] The heat treatment temperature is 50–150℃, and the treatment time is 10–120 min.
[0029] Furthermore, the preparation method of hydroxylated carbon nanotubes involves acid treatment of the carbon nanotubes. Specifically, defects are etched onto the surface of the carbon nanotubes using acid to prepare an acid-treated carbon nanotube solution. Acid treatment involves placing the carbon nanotubes in a mixed solution for acidification. The ratio of nitric acid (12 mol / L): sulfuric acid (18 mol / L) in the mixed solution is 1–3:1–3 (V:V).
[0030] Second, the present invention provides a method for preparing the aforementioned silicon-carbon nanotube composite material, comprising the following steps:
[0031] An aqueous dispersion of iminodiacetic acid was formed, and hydroxylated silicon particles and hydroxylated carbon nanotubes were added and blended to obtain a blend.
[0032] The blend was subjected to hydrothermal treatment to obtain a silicon-carbon nanotube composite material.
[0033] Furthermore, in the aqueous dispersion of aminodiacetic acid, the concentration of iminodiacetic acid is 0.2–1.0 mg / ml.
[0034] Furthermore, the blending is carried out by ultrasonication and stirring, with ultrasonication time of 0.5 to 2 hours and stirring time of 2 to 8 hours.
[0035] Furthermore, the process parameters for hydrothermal treatment are: temperature 120–200℃ and time 5–24h.
[0036] Further, after hydrothermal treatment, it undergoes filtration, washing, and drying. The washing conditions involve alternating washing with deionized water and ethanol.
[0037] Second, the present invention provides the application of the aforementioned silicon-carbon nanotube composite material in the negative electrode of a lithium-ion battery.
[0038] <Example>
[0039] Example 1
[0040] This embodiment provides a silicon-carbon nanotube composite material, the preparation method of which includes the following steps:
[0041] (a) Silicon particles were treated in a strong oxidizing solution of sulfuric acid: H2O2 = 3:1 (volume ratio) at 100°C for 30 min to obtain surface-functionalized silicon materials; carbon nanotubes with an aspect ratio of 5 were acid-treated in a mixed solution of nitric acid and sulfuric acid (nitric acid: sulfuric acid = 1:1 (V:V)) to obtain acidified carbon nanotubes.
[0042] (b) Disperse 0.2g iminodiacetic acid in 500ml deionized water and stir magnetically for 1h. Add 0.2g acidified carbon nanotubes and sonicate for 1h to disperse evenly. Then add 2g functionalized silicon material and continue to sonicate for 1h and stir for 4h to mix thoroughly.
[0043] (c) The above mixed solution was transferred to a reactor and hydrothermally reacted at 160°C for 10 hours, then allowed to cool naturally.
[0044] (d) The hydrothermal reaction product was filtered, washed, and vacuum dried at 100°C for 6 h to obtain a covalently crosslinked silicon / carbon nanotube composite material of iminodiacetic acid.
[0045] Example 2
[0046] This embodiment provides a silicon-carbon nanotube composite material, the preparation method of which includes the following steps:
[0047] (a) Silicon particles were treated in a strong oxidizing solution of sulfuric acid: H2O2 = 3:1 (volume ratio) at 100°C for 30 min to obtain surface-functionalized silicon materials; carbon nanotubes with an aspect ratio of 5 were acid-treated in a mixed solution of nitric acid and sulfuric acid (nitric acid: sulfuric acid = 1:1 (V:V)) to obtain acidified carbon nanotubes.
[0048] (b) Disperse 0.1g iminodiacetic acid in 500ml deionized water and stir magnetically for 1h. Add 0.2g acidified carbon nanotubes and sonicate for 1h to disperse evenly. Then add 2g functionalized silicon material and continue to sonicate for 1h and stir for 4h to mix thoroughly.
[0049] (c) The above mixed solution was transferred to a reactor and hydrothermally reacted at 160°C for 10 hours, then allowed to cool naturally.
[0050] (d) The hydrothermal reaction product was filtered, washed, and vacuum dried at 100°C for 6 h to obtain a covalently crosslinked silicon / carbon nanotube composite material of iminodiacetic acid.
[0051] Example 3
[0052] This embodiment provides a silicon-carbon nanotube composite material, the preparation method of which includes the following steps:
[0053] (a) Silicon particles were treated in a strong oxidizing solution of sulfuric acid:H2O2 = 3:1 (volume ratio) at 100°C for 30 min to obtain surface-functionalized silicon materials; carbon nanotubes with an aspect ratio of 5 were acid-treated in a mixed solution of nitric acid and sulfuric acid (nitric acid:sulfuric acid = 1:3 (V:V)) to obtain acidified carbon nanotubes.
[0054] (b) Disperse 0.05g iminodiacetic acid in 500ml deionized water and stir magnetically for 1h. Add 0.2g acidified carbon nanotubes and sonicate for 1h to disperse evenly. Then add 2g functionalized silicon material and continue to sonicate for 1h and stir for 4h to mix thoroughly.
[0055] (c) The above mixed solution was transferred to a reactor and hydrothermally reacted at 140°C for 20 hours, then allowed to cool naturally.
[0056] (d) The hydrothermal reaction product was filtered, washed, and vacuum dried at 100°C for 6 h to obtain a covalently crosslinked silicon / carbon nanotube composite material of iminodiacetic acid.
[0057] <Comparative Example>
[0058] Comparative Example 1
[0059] This comparative example provides a silicon-carbon nanotube composite material, the preparation method of which includes the following steps:
[0060] (a) Silicon particles were treated in a strong oxidizing solution of sulfuric acid: H2O2 = 3:1 (volume ratio) at 100°C for 30 min to obtain surface-functionalized silicon materials; carbon nanotubes with an aspect ratio of 5 were acid-treated in a mixed solution of nitric acid and sulfuric acid (nitric acid: sulfuric acid = 1:1 (V:V)) to obtain acidified carbon nanotubes.
[0061] (b) Disperse 0.2g of acidified carbon nanotubes in 500ml of deionized water, sonicate for 1h to disperse evenly, add 2g of functionalized silicon material, and continue sonicating for 1h and stirring for 4h to mix thoroughly.
[0062] (c) The above mixed solution was transferred to a reactor and hydrothermally reacted at 160°C for 10 hours, then allowed to cool naturally.
[0063] (d) The hydrothermal reaction product was filtered, washed, and vacuum dried at 100°C for 6 h to obtain a covalently crosslinked silicon / carbon nanotube composite material of iminodiacetic acid.
[0064] <Experimental Example>
[0065] The iminodiacetic acid covalently crosslinked silicon / carbon nanotube composite materials prepared in Examples 1, 2, and 3, and the silicon / carbon nanotube composite material prepared in Comparative Example 1, were used as battery negative electrode materials. They were mixed with conductive carbon black and sodium carboxymethyl cellulose binder in a mass ratio of 8:1:1 to prepare an electrode slurry. The slurry was coated onto copper foil and dried in a vacuum drying oven for 12 hours to obtain the lithium-ion battery negative electrode sheet. CR2032 coin cells were assembled in a glove box. After assembly and standing for 12 hours, various electrochemical performance parameters were tested using a Xinwei testing cabinet. Cyclic voltammetry tests were performed at a rate of 0.1 Mv / s in the range of 0.001–3 V.
[0066] SEM image
[0067] Figure 1 The image shows a SEM image of the iminodiacetic acid covalently crosslinked silicon / carbon nanotube composite material prepared in Example 2.
[0068] Figure 1 This indicates that iminodiacetic acid has successfully anchored silicon particles onto carbon nanotubes, enabling more efficient electron transport. At the same time, the anchoring force effectively alleviates the interfacial stress changes of silicon particles during charging and discharging, thereby improving the cycle stability of the electrode.
[0069] Cyclic Voltmeter
[0070] Figure 2 The image shows the cyclic voltammogram of the iminodiacetic acid covalently crosslinked silicon / carbon nanotube composite material prepared in Example 2.
[0071] Figure 2 The reduction peak that appears at 0.7V to 1.5V during the initial lithium insertion process is mainly due to the reduction decomposition of the electrolyte at the solid-liquid interface, which generates a solid electrolyte interphase (SEI) film. This peak disappears during subsequent cycles, indicating that the material has good reversibility.
[0072] Cyclic performance test chart
[0073] Figure 3 Cyclic performance test diagram of coin cell fabricated from iminodiacetic acid covalently crosslinked silicon / carbon nanotube composite material prepared in Example 2.
[0074] Figure 3 The results show that the material has a high reversible specific capacity and good cycling stability. After 100 cycles at a high current density of 1 A / g, it still has a specific capacity of 1750 mAh / g.
[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A silicon-carbon nanotube composite material, characterized by, Hydroxylated silicon particles, hydroxylated carbon nanotubes, and iminodiacetic acid are obtained by dehydration; the hydroxylated silicon particles / hydroxylated carbon nanotubes are obtained by dehydration condensation with the carboxyl groups in iminodiacetic acid, so that silicon particles with Si-O bonds are anchored to carbon nanotubes with CO bonds by iminodiacetic acid; the mass ratio of iminodiacetic acid, hydroxylated carbon nanotubes, and hydroxylated silicon particles is 1~10:1~15:8~40; the particle size of silicon particles ranges from 50 to 200 nm; the aspect ratio of carbon nanotubes ranges from 0.2 to 15.
2. The silicon-carbon nanotube composite of claim 1, wherein, The method for preparing hydroxylated silicon particles involves treating the silicon particles in an oxidizing solution at a certain temperature.
3. The silicon-carbon nanotube composite of claim 2, wherein, The heat treatment temperature is 50~150℃, and the treatment time is 10~120min.
4. The silicon-carbon nanotube composite of claim 2, wherein, The oxidizing solution is a mixture of sulfuric acid and H2O2.
5. The silicon-carbon nanotube composite of claim 1, wherein, The preparation method of hydroxylated carbon nanotubes is to obtain carbon nanotubes by acid treatment.
6. A method for producing the silicon-carbon nanotube composite material according to any one of claims 1 to 5, characterized by, Includes the following steps: An aqueous dispersion of iminodiacetic acid was formed, and then hydroxylated silicon particles and hydroxylated carbon nanotubes were added and blended to obtain a blend. The blend was subjected to hydrothermal treatment to obtain a silicon-carbon nanotube composite material.
7. The method for preparing the silicon-carbon nanotube composite material according to claim 6, characterized in that, The process parameters for hydrothermal treatment are: temperature 120~200℃, time 5~24h.
8. The application of a silicon-carbon nanotube composite material as described in any one of claims 1 to 5 or a composite material obtained by the preparation method as described in claim 6 or 7 in a lithium-ion battery anode.