Lithium ion battery negative electrode material with ultrahigh specific capacity and preparation method thereof
By preparing silicon-oxygen-carbon composite materials, silicon vacancies and bound excitons are formed by rapid cooling under high temperature and vacuum using CVD. Combined with the BEC mechanism, the stoichiometric limitations of silicon-based anodes are overcome, achieving high specific capacity and good cycle stability, which is suitable for large-scale energy storage systems in portable electronic devices and electric vehicles.
Patent Information
- Application Number
- CN202510918412.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-03
- Publication Date
- 2025-11-18
AI Technical Summary
The specific capacity of traditional graphite anodes for lithium-ion batteries is approaching its performance limit, while silicon-based anode materials are difficult to overcome stoichiometric limitations and are difficult to mass-produce.
Silicon-oxygen-carbon composite materials were prepared under high temperature and vacuum conditions using chemical vapor deposition (CVD). By rapidly cooling the material, vacancy defects were retained to form silicon vacancies and bound excitons. The directional and ordered arrangement of lithium/silicon was achieved by utilizing the quasi-Bose-Einstein condensation (BEC) mechanism. Carbon was combined to provide a conductive network and buffer volume expansion.
At a current density of 420 mA g⁻¹, the initial discharge specific capacity reaches 5,947.54 mAh g⁻¹, the initial coulombic efficiency reaches 83.42%, the cycle stability is excellent, the process is simple and can be mass-produced, and the cost is controllable.
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Figure CN120978030A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery anode technology, and particularly relates to an ultra-high specific capacity lithium-ion battery anode material and its preparation method. Background Technology
[0002] The theoretical specific capacity of traditional lithium-ion battery graphite anodes is only 372 mAh g. -1 This has already approached its performance limit. In comparison, the theoretical capacity of silicon-based anodes is approximately 4200 mAh / g, but it has long been considered difficult to break through further because, stoichiometrically, the maximum lithium-to-silicon ratio is limited to Li. 4.4 Si. It is noteworthy that silicon is a condensed matter, and the migration behavior of lithium ions within it can be modulated by unconventional physical effects—such as Bose-Einstein condensation (BEC). When electrons donated by lithium atoms combine with holes formed by silicon vacancies, bound excitons are generated, leading to a directional, ordered, and high-density arrangement of lithium and silicon atoms. This process holds promise for breaking through conventional stoichiometric limitations, laying the foundation for ultra-high capacity lithium-ion battery anodes, and providing new avenues for performance upgrades in portable electronic devices, electric vehicles, and energy storage systems.
[0003] Based on the above understanding, this invention proposes a silicon-oxygen-carbon anode material and its preparation method. This anode is modulated by the BEC mechanism at 420 mAg. -1 The initial discharge specific capacity at current density can reach 5947.54 mAh g. -1 The initial coulombic efficiency reached 83.42%, demonstrating good cycle stability. This silicon-oxygen-carbon composite material was obtained using CVD combined with rapid cooling, and has achieved a daily production scale of 10 kg, showing great application potential in the field of lithium-ion batteries and is expected to play an important role in future energy storage technologies. Summary of the Invention
[0004] This invention overcomes the shortcomings of existing technologies, such as low specific capacity and difficulty in large-scale preparation, and provides a lithium-ion battery anode material with ultra-high specific capacity that can be mass-produced and its preparation method.
[0005] The technical solution adopted in this invention is as follows:
[0006] An ultra-high specific capacity lithium-ion battery anode material is obtained by reacting a gaseous, liquid, or solid silicon source, a gaseous carbon source, and a gaseous oxygen source under high temperature and vacuum conditions in a reactor tube, followed by rapid cooling of the reactor tube after the reaction. Specifically:
[0007] 1. Anode materials and their structure
[0008] Silicon-oxygen-carbon composite material is used as the negative electrode active material.
[0009] The composite material is obtained by reacting a gaseous, liquid, or solid silicon source with a gaseous carbon source and an oxygen source under high temperature and vacuum conditions, followed by rapid cooling by introducing nitrogen gas after the reaction is completed.
[0010] 2. Raw material selection
[0011] Silicon source: can be in gaseous, liquid or solid form, or a combination of the three in any proportion;
[0012] Gaseous silicon source: silane (SiH4).
[0013] Liquid silicon sources: cyclotetramethyldisiloxane (D4), 3-aminopropyltrimethoxysilane, tri-n-butylaminomethylsilane.
[0014] Solid silicon source: silicon particles.
[0015] Carbon source: one or more of methane, ethane, ethylene, acetylene, methanol or ethanol.
[0016] Oxygen source: oxygen, carbon dioxide, or any combination of the two.
[0017] Protective atmosphere: one or more of argon, nitrogen, and helium.
[0018] 3. Preparation method
[0019] The chemical vapor deposition (CVD) process is employed, and the steps are as follows:
[0020] Vacuuming: Evacuate the reactor tubes to 10... -5 –5×10 3 Pa.
[0021] Silicon-oxygen co-deposition: Under vacuum conditions below 10 Pa, silicon and oxygen source gases are introduced, while an inert protective gas is introduced; the temperature is raised to 500–3000℃, and the reaction is carried out for 0.1–24 h.
[0022] Carbonization and defect control: Subsequently, carbon source gas, hydrogen and trace oxygen (trace amounts of oxygen or oxygen-containing gas, usually ≤10 sccm) are introduced to maintain the carbon source:hydrogen molar ratio of 100:1–1:100; after the reaction is completed, rapid cooling is introduced to room temperature to obtain silicon-oxygen-carbon material.
[0023] Furthermore, it is crucial to maintain the presence of trace amounts of oxygen or oxygen-containing gases during the silicon-oxygen co-deposition and carbonization process. The presence of these trace amounts of oxygen or oxygen-containing gases can form silicon vacancies in the final silicon-carbon-oxygen material, thereby improving its performance.
[0024] Furthermore, the rapid cooling condition is a cooling rate of not less than 200°C / minute. This cooling process maximizes heat exchange efficiency by introducing circulating cooling water into the metal cooling jacket covering the reactor tubes, combined with high-flow-rate (not less than 2 slm) inert nitrogen internal purging. Rapid cooling can retain vacancy defects in the material generated at high temperatures, thereby obtaining the final silicon-oxygen-carbon material.
[0025] The beneficial effects of this invention are:
[0026] High specific capacity: at 420mAg -1 At the current density, the initial discharge specific capacity can reach 5947.54 mAh g. -1 Significant breakthrough in the theoretical capacity of silicon-based materials (≈4200mAh g). -1 The initial coulombic efficiency reached 83.42%, with excellent cycle stability. Mechanistic advantages: The carbon phase provides an excellent conductive network and buffers silicon volume expansion. High-density silicon vacancies provide abundant active sites for lithium-ion transport. Lithium atom electrons combine with silicon holes to form bound excitons, inducing quasi-Bose-Einstein condensation (BEC) within the silicon bulk phase, promoting the directional and ordered arrangement of lithium / silicon, thus overcoming the limitations of stoichiometry. Scalable preparation: The process is simple, enabling continuous production of approximately 10 kg per day, with controllable costs, facilitating industrial-scale promotion.
[0027] This invention thus combines high performance and manufacturability, providing a competitive next-generation lithium-ion battery anode solution for portable electronic devices, electric vehicles, and large-scale energy storage systems. Attached Figure Description
[0028] Figure 1 An optical image of the negative electrode material of Example 1;
[0029] Figure 2 This is a TEM image of the silicon-oxygen-carbon material from Example 1; the scale bar in the image is 5 nm.
[0030] Figure 3 The image shows a HAADF-STEM image of Si nanodots in the silicon-oxygen-carbon composite material of Example 1; the scale bar in the image is 10 nm.
[0031] Figure 4 The charge-discharge curves of the negative electrode of the lithium battery in Example 1 are shown.
[0032] Figure 5 This is a TEM image of the silicon-oxygen-carbon material from Example 2; the scale bar in the image is 5 nm.
[0033] Figure 6 The image shows a HAADF-STEM image of Si nanodots in the silicon-oxygen-carbon composite material of Example 2; the scale bar in the image is 5 nm.
[0034] Figure 7 The charge-discharge curves are for the negative electrode of the lithium battery in Example 2.
[0035] Figure 8 This is a TEM image of the silicon-oxygen-carbon material in Example 3;
[0036] Figure 9 HAADF-STEM image of Si nanodots in the silicon-oxygen-carbon composite material of Example 3;
[0037] Figure 10 The charge-discharge curves are for the negative electrode of the lithium battery in Example 3.
[0038] Figure 11 The charge-discharge curves are for the negative electrode of the lithium battery in Example 4.
[0039] Figure 12 The discharge specific capacity was calculated to be 3063.26 mAh g using the constant current intermittent titration method. -1 The lithium-ion diffusion coefficient under certain conditions.
[0040] Figure 13 The discharge specific capacity was calculated to be 3389.41 mAh g using the constant current intermittent titration method. -1 The lithium-ion diffusion coefficient under certain conditions.
[0041] Figure 14 The discharge specific capacity was calculated to be 4094.83 mAh g using the constant current intermittent titration method. -1 The lithium-ion diffusion coefficient under certain conditions. Detailed Implementation
[0042] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0043] Example 1
[0044] A lithium-ion battery anode based on silicon-oxygen-carbon material, wherein the preparation method of silicon-oxygen-carbon material is as follows:
[0045] 1) Preparation of silicon-oxygen-carbon materials
[0046] First, the reactor tubes were evacuated to a vacuum level of 10. -3The pressure was initially set at 100 Pa, then argon was introduced, followed by 300 sccm of silane and 100 sccm of oxygen, maintaining the pressure at 100 Pa. The temperature was then increased to 800 °C at a rate of 1 °C / min, and the reaction was carried out for 10 h under an argon protective atmosphere. The temperature was then increased to 1000 °C, and 200 sccm of methane and 50 sccm of hydrogen were introduced, along with less than 10 sccm of oxygen, for a further 24 h. After the reaction, the furnace tubes were rapidly cooled with water, combined with internal purging with inert nitrogen at a flow rate of 2 slm, reducing the temperature to room temperature within 3 minutes at a cooling rate of 360 °C / min. Optical images of the product were obtained as follows. Figure 1 As shown. The high-resolution electron microscope image of the product is shown below. Figure 2 As shown. HAADF-STEM image of Si nanodots in silicon-oxygen-carbon composite material. Figure 3 As shown. From Figure 2 , 3 Many defects and crystal boundaries can be clearly seen, which proves the presence of silicon vacancies and bound excitons, thus producing quasi-Bose-Einstein condensates (BEC) inside silicon.
[0047] 2) Electrochemical test results
[0048] After testing, the charge-discharge curve of the negative electrode material of this invention is as follows: Figure 4 As shown in the figure. It can be seen from the figure that at 420 mA g -1 At the specified current density, the discharge specific capacity of the silicon-oxygen-carbon anode material reached 5947.54 mAh g during the first cycle. -1 This breakthrough surpasses the theoretical specific capacity limit of silicon materials, demonstrating enormous potential in the field of energy storage. Simultaneously, it achieves a coulombic efficiency of 83.42% for the first time, exhibiting excellent cycle performance.
[0049] Example 2
[0050] 1) Preparation of silicon-oxygen-carbon materials
[0051] First, the reactor tubes were evacuated to a vacuum level of 10. -3 The pressure was initially set at 100 Pa, then argon was introduced, followed by 300 sccm of silane and 10 sccm of oxygen, maintaining the pressure at 100 Pa. The temperature was then increased to 800 °C at a rate of 1 °C / min and reacted under an argon atmosphere for 15 h. The temperature was then increased to 1000 °C, and 300 sccm of methane and 100 sccm of hydrogen were introduced simultaneously, along with 5 sccm of oxygen, reacting for 10 h. After the reaction, the furnace tubes were rapidly cooled with water, combined with internal purging with inert nitrogen at a flow rate of 2.5 slm, cooling to room temperature within 2 minutes at a cooling rate of 400 °C / min. The resulting material was analyzed by TEM. Figure 5 As shown, the HAADF-STEM image of Si nanodots in the silicon-oxygen-carbon composite material is as follows: Figure 6 As shown.
[0052] 2) Electrochemical test results
[0053] After testing, the charge-discharge curve of the present invention is as follows: Figure 7 As shown in the figure. It can be seen from the figure that at 420mAg... -1 At the specified current density, the discharge specific capacity of the silicon-oxygen-carbon anode material of this invention reached 5542.98 mAh g during the first cycle. -1 Meanwhile, the initial coulombic efficiency can reach 85.25%, demonstrating good cycle performance.
[0054] Example 3
[0055] 1) Preparation of silicon-oxygen-carbon materials
[0056] First, the reactor tubes were evacuated to a vacuum level of 10. -3 The pressure was initially set at 100 Pa, then argon was introduced, followed by 300 sccm of silane and 10 sccm of oxygen, maintaining the pressure at 100 Pa. The temperature was then increased to 800 °C at a rate of 1 °C / min and reacted under an argon atmosphere for 15 h. The temperature was then increased to 1500 °C, with 300 sccm of methane and 100 sccm of hydrogen introduced, along with 5 sccm of oxygen, and the reaction was continued for 15 h. After the reaction, the furnace tubes were rapidly cooled with water, combined with internal purging with inert nitrogen at a flow rate of 2 slm, reducing the temperature to room temperature within 5 minutes at a cooling rate of 200 °C / min. TEM images of the obtained material are shown below. Figure 8 As shown, the HAADF-STEM image of Si nanodots in the silicon-oxygen-carbon composite material is as follows: Figure 9 As shown.
[0057] 2) Electrochemical test results
[0058] After testing, the charge-discharge curve of the present invention is as follows: Figure 10 As shown in the figure. It can be seen from the figure that at 420mAg... -1 At the specified current density, the discharge specific capacity of the silicon-oxygen-carbon anode material reached 5469.63 mAh g during the first cycle. -1 Meanwhile, the initial coulomb efficiency can reach 73.48%, demonstrating good cycle performance.
[0059] Example 4
[0060] 1) Preparation of silicon-oxygen-carbon materials
[0061] First, the reactor tubes were evacuated to a vacuum level of 10. -3Pa, then argon gas is introduced, followed by 300 sccm of silane and 20 sccm of oxygen, maintaining the pressure at 100 Pa; subsequently, the temperature is increased to 800 °C at a rate of 1 °C / min and reacted under an argon atmosphere for 15 h; then the temperature is increased to 1000 °C, and 300 sccm of methane and 100 sccm of hydrogen are introduced for reaction, while 5 sccm of oxygen is introduced simultaneously, reacting for 20 h; after the reaction is completed, the reaction furnace tube is rapidly cooled by water cooling, combined with internal purging with inert nitrogen at a flow rate of 3 slm, cooling to room temperature within 5 minutes, with a cooling rate of 360 °C / min, to obtain a silicon-oxygen-carbon composite material.
[0062] 2) Electrochemical test results
[0063] After testing, the charge-discharge curve of the present invention is as follows: Figure 11 As shown in the figure. It can be seen from the figure that at 420 mA g -1 At the specified current density, the discharge specific capacity of the silicon-oxygen-carbon anode material reached 5188.26 mAh g during the first cycle. -1 Meanwhile, the initial coulombic efficiency can reach 82.31%, demonstrating good cycle performance.
[0064] This invention achieves a significant increase in the discharge specific capacity of silicon-oxygen-carbon anode materials through process control. The underlying mechanism is inferred to be the combination of lithium atom electrons and silicon holes to form bound excitons, inducing quasi-Bose-Einstein condensation (BEC) within the silicon bulk phase, promoting the directional and orderly arrangement of lithium / silicon, thereby overcoming the limitations of stoichiometry. Figure 12-14 As shown, the ion diffusion coefficient of lithium ions at different specific capacities was calculated using the constant current intermittent titration method. Where τ is the constant current pulse duration, m B It is the quality of the active material, V m M is the molar volume per unit cell. B S is the molecular weight of the material, S is the active surface area of the electrode, and ΔE is the molecular weight of the material. s It is the voltage difference during steady state, ΔE τ It is the voltage difference during the constant current pulse. Figure 12 The discharge specific capacity is 3063.26 mAh g. -1 The diffusion coefficient is 3.8 × 10⁻⁶. -12 cm 2 s -1 , Figure 13 The discharge specific capacity is 3389.41 mAh g. -1 The diffusion coefficient is 3.0 × 10⁻⁶. -12 cm 2 s -1 , Figure 14 The discharge specific capacity is 4094.83 mAh g. -1 The diffusion coefficient is 2.7 × 10⁻⁶.-12 cm 2 s -1 As can be seen, the average diffusion coefficient of lithium ions gradually decreases with increasing specific capacity. This is because lithium atoms combine with silicon vacancies to form bound excitons, inducing quasi-BEC states within the bulk silicon phase. Higher specific capacity leads to an increase in the number of lithium atoms forming excitons, resulting in a decrease in the collective diffusion coefficient of lithium atoms, thus demonstrating the quasi-BEC mechanism proposed in this invention.
Claims
1. A lithium-ion battery anode material with ultra-high specific capacity, characterized in that, The negative electrode uses a silicon-oxygen-carbon composite material, which is obtained by reacting a gaseous, liquid or solid silicon source, a gaseous carbon source and a gaseous oxygen source under high temperature and vacuum conditions. After the reaction is completed, it is rapidly cooled by filling with nitrogen.
2. The lithium-ion battery anode material according to claim 1, characterized in that, When this anode material is used in lithium-ion batteries, it utilizes the combination of electrons provided by lithium atoms and holes generated by silicon vacancies to form bound excitons, inducing quasi-Bose-Einstein condensation (BEC) within the silicon bulk phase, at 420 mAg. -1 The initial discharge specific capacity at current density reached 5947.54 mAh g. -1 The initial coulomb efficiency reached 83.42%.
3. The lithium-ion battery anode material according to claim 1, characterized in that, The silicon source is a gaseous, liquid, or solid silicon source, preferably one or more of silane, cyclotetramethyldisiloxane, 3-aminopropyltrimethoxysilane, tri-n-butylaminomethylsilane, or silicon particles, combined in any proportion.
4. The lithium-ion battery anode material according to claim 1, characterized in that, The carbon source is one or more of methane, ethane, ethylene, acetylene, methanol, or ethanol, combined in any proportion.
5. The lithium-ion battery anode material according to claim 1, characterized in that, A trace amount of oxygen or oxygen-containing gas should be maintained during the silicon-oxygen co-deposition and carbonization process.
6. The method for preparing the ultra-high specific capacity lithium-ion battery anode material according to claim 1, characterized in that, include: Chemical vapor deposition (CVD) is used to introduce a silicon source and a certain amount of oxygen source gas into a vacuum reactor tube at <10 Pa, and inert protective gas is introduced. After heating to a specific temperature and reacting for a certain period of time, carbon source gas, hydrogen and trace oxygen are introduced. After the reaction is completed, the reactor tube is rapidly cooled to room temperature to retain the vacancy defects in the material generated at high temperature, thus obtaining the final silicon-oxygen-carbon material. The rapid cooling is achieved by introducing circulating cooling water into the metal cooling jacket covering the reactor tube, combined with internal purging with inert nitrogen gas at a high flow rate of not less than 2 slm.
7. The method according to claim 6, characterized in that, The oxygen source gas is oxygen, carbon dioxide, or any combination of the two.
8. The method according to claim 6, characterized in that, The specific temperature is 500–3000℃.
9. The method according to claim 6, characterized in that, The reaction time is 0.1–24 h.
10. The method according to claim 6, characterized in that, The rapid cooling condition is that the cooling rate is not less than 200℃ / minute.