A porous carbon and silicon-carbon material, its preparation method, and its application in lithium-ion batteries.

Abstract

This invention specifically discloses a porous carbon, a silicon-carbon material, its preparation method, and its application in lithium-ion batteries. Using phenol metal salt as a carbon source, this invention prepares a porous carbon material with high pore size ordering via an in-situ template method. A novel silicon-carbon material is then prepared using this porous carbon material as a substrate through chemical vapor deposition. The porous carbon prepared by this invention has advantages such as high microporosity and high uniformity and order of pore size. When used for further preparation of silicon-carbon materials via chemical vapor deposition, the diffusion resistance of silane gas within the porous carbon material is lower, which is beneficial for improving silicon deposition efficiency. Simultaneously, it also facilitates the uniform dispersion and fixation of silicon particles within the porous carbon channel structure, preventing silicon particle aggregation. Furthermore, the limitation effect of the micropore size effectively controls the nucleation and growth of silicon particles, resulting in silicon particles of uniform size. Applying the above-mentioned silicon-carbon material to lithium-ion batteries helps improve the electrochemical performance of electrochemical devices containing this silicon-carbon anode material.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a porous carbon and silicon-carbon material, its preparation method, and its application in lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries play an increasingly important role in modern human daily life and industrial activities. Among them, the performance indicators of anode materials, including lithium storage specific capacity, initial charge and discharge capacity, and cycle stability, have a significant impact on battery energy density, coulombic efficiency, energy efficiency, and service life.

[0003] Graphite possesses advantages such as low cost, good uniformity, low lithium extraction voltage, small hysteresis voltage after lithium insertion / extraction, and good conductivity, making it the mainstream anode material for lithium-ion batteries. However, limited by the interlayer lithium storage mechanism, the theoretical specific capacity of graphite anodes is only 372 mAh / g, and the actual specific capacity is already very close to the theoretical specific capacity, making it difficult to significantly improve the overall energy density of the battery. Therefore, novel high-specific-capacity anode materials urgently need to be developed. The alloying reaction product of silicon-based anodes and lithium ions is Li. 4.4 Si, with a specific capacity contributing up to 4200 mAh / g, is a promising new anode material for high-energy-density lithium-ion batteries. However, silicon anodes still face significant technical challenges. For example, silicon undergoes a volume expansion of over 300% during lithium intercalation, leading to active particle pulverization, electrode structure damage, and electro-deactivation, resulting in rapid capacity decay. Furthermore, side reactions between the silicon-based anode and the electrolyte cause continuous growth of the solid-state electrolyte interface (SEI), reducing coulombic efficiency and further exacerbating battery performance degradation. Additionally, silicon's inherent poor conductivity also affects the battery's charge-discharge performance.

[0004] Currently, researchers have developed strategies such as nanostructuring, carbon coating, silicon suboxide, pre-lithiation, and amorphization to address the aforementioned problems of silicon anodes. Sand-milled silicon-carbon materials (obtained by sand-milling carbon and silicon materials followed by high-temperature sintering) have low capacity and poor cycle stability; pre-magnesium and pre-lithiated silicon suboxides have low initial efficiency, high price, and unsatisfactory cycle stability. However, novel silicon-carbon technology based on the adsorption and pyrolysis of silanes within porous carbon pores to generate amorphous nano-silicon has advantages such as high specific capacity, high initial efficiency, and good cycle stability. However, current methods for preparing porous carbon mainly involve carbonization and activation steps. Activation methods primarily include physical activation (such as using steam or carbon dioxide as activators) and chemical activation (such as using alkalis or acids as activators). Porous carbon prepared using the carbonization + activation method suffers from drawbacks such as complex processes, high cost, low yield, and poor pore size uniformity. Therefore, there is an urgent need to develop a novel method for preparing porous carbon to solve these problems. Summary of the Invention

[0005] To address the problems of complex processes, high costs, and poor pore size uniformity in existing porous carbon preparation processes, this invention provides a porous carbon, silicon-carbon material, preparation method, and its application in lithium-ion batteries. This invention uses phenol metal salt as a carbon source and prepares a porous carbon material with high pore size ordering through an in-situ template method. A novel silicon-carbon material prepared by vapor deposition using this porous carbon material as a substrate possesses advantages such as high compaction density, high initial efficiency, high rate capability, and long cycle life, showing broad application prospects in the field of lithium-ion batteries.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing porous carbon, comprising the following steps:

[0008] S1, Under a protective atmosphere, phenol metal salt is calcined at 600℃~1100℃ for 1h~5h to obtain carbon-based material;

[0009] S2, the carbon-based material is pulverized to make its D50 3μm~15μm;

[0010] S3, the ash content of the pulverized carbon-based material is tested. If the ash content is ≤0.2%, proceed directly to S4; if the ash content is >0.2%, the pulverized carbon-based material is subjected to several acid washing and water washing cycles until the ash content of the carbon-based material is ≤0.2% or the pH of the washing solution is <7.

[0011] S4. Test the oxygen content of the pulverized carbon material. If the oxygen content is ≤0.05mmol / g, proceed directly to S5. If the oxygen content is >0.05mmol / g, calcine the pulverized carbon material at 700℃~1200℃ for 0.5h~3h under a protective atmosphere before proceeding to S5.

[0012] S5, test the particle size of the carbon material in S4. If it meets the requirements of D0 being 1μm to 5μm, D50 being 3μm to 15μm, and D100 being 10μm to 30μm, no further processing is required. If it does not meet the above particle size requirements, the carbon material is crushed and graded until the particle size meets the requirements to obtain porous carbon.

[0013] Compared with existing technologies, the method for preparing porous carbon provided by this invention has the following advantages:

[0014] (1) In this invention, phenol metal salt is used as carbon source. During the carbonization process, phenol groups will gradually crosslink to form an aromatic network and then form an amorphous carbon material. Metal ions combine with oxygen elements in phenol hydroxyl groups to form metal oxides. Metal oxides can act as in-situ embedded alkaline pore-forming agents. During the carbonization process, metal oxides are limited by the carbon material and cannot continue to fuse and grow, thus forming extremely small nanoparticles (particle size < 5 nm). At the same time, the in-situ formed metal oxides are uniformly dispersed in the carbon material. Furthermore, the metal oxides etch the surrounding carbon material to form pores, thereby forming a highly ordered pore structure in the carbon material with consistent pore size. When preparing silicon carbon materials, silane gas can more easily enter the pores of porous carbon, which is beneficial to reduce the mass transfer resistance of silane gas, thereby helping to uniformly disperse and fix silicon particles, avoid the aggregation of silicon particles, and reduce the floating silicon phenomenon.

[0015] (2) Phenol metal salts, as carbon sources, have a higher carbon retention rate compared to other organic acid metal salts, which can improve the yield of porous carbon.

[0016] (3) By controlling the carbonization temperature and time of phenol metal salt, it is beneficial to regulate the pore size and pore structure of porous carbon materials, so that their specific surface area is 1000 m². 2 / g~3000m 2 / g, total pore volume is 0.6cm³ 3 / g~2cm 3 / g, the proportion of micropore volume to total pore volume is more than 80%, and the average pore size is 1.5nm to 3nm. The high proportion of micropores is conducive to the formation of smaller confined nano-silicon particles after silane adsorption and cracking. Smaller silicon particles are conducive to alleviating the volume expansion during the lithiation process, thereby improving the electrochemical performance of silicon-carbon materials.

[0017] (4) This invention controls the particle size of porous carbon in a graded manner, making its D0 1μm~5μm, D50 3μm~15μm, and D100 10μm~30μm. A D0 value that is too small will result in an excessively large specific surface area of ​​the porous carbon material, which in turn will increase the specific surface area of ​​the prepared vapor-deposited silicon-carbon material, leading to an increase in the lithium ions consumed to form the SEI and reducing the initial coulombic efficiency of the silicon-carbon anode. A D100 value that is too large will prevent the effective deposition of silicon particles in the pores inside the porous carbon, thereby reducing the amount of silicon deposited and thus reducing the specific capacity of the silicon-carbon material. In addition, a D100 value that is too large will also increase the diffusion distance of lithium ions, reducing the fast charge / discharge performance of the silicon-carbon material.

[0018] (5) The highly ordered pore structure of porous carbon can serve as a support framework, reducing the expansion and contraction of silicon volume during charging and discharging, thereby improving the structural stability and cycle life of the material; at the same time, the highly ordered pore structure is conducive to carrier transport, improving the electrochemical reaction rate of electrode materials, thereby enhancing the overall performance of the battery.

[0019] Further, S1, the protective atmosphere gas is one or more of nitrogen, argon, helium, carbon dioxide or water vapor.

[0020] Preferably, in S1, the protective atmosphere is carbon dioxide or water vapor.

[0021] Carbon dioxide or water vapor can not only act as a protective gas, but also as an activator in the pore-forming process, further increasing the porosity and specific surface area of ​​porous carbon.

[0022] Further, in S1, the temperature is increased to 600℃ to 1100℃ at a rate of 2℃ / min to 25℃ / min, preferably 5℃ / min to 10℃ / min.

[0023] Preferably, in S1, the calcination temperature is 800℃~1000℃, and the calcination time is 2h~4h.

[0024] Further, in S1, the phenol metal salt is one or more of lithium phenolate, sodium phenolate, potassium phenolate, magnesium phenolate, calcium phenolate, zinc phenolate, manganese phenolate, aluminum phenolate, or iron phenolate.

[0025] In a specific embodiment of the present invention, in S1, the method for preparing the phenol metal salt includes the following steps: adding phenol and a metal source to a solvent, mixing them evenly, removing the solvent, and obtaining the phenol metal salt; wherein, the metal source includes one or more of the metal oxides or hydroxides corresponding to lithium, sodium, potassium, magnesium, calcium, zinc, manganese, aluminum, and iron.

[0026] Furthermore, the solvent is water or an alcohol.

[0027] Furthermore, the molar ratio of phenol to the metal element in the metal source is 1:1 to 1:3, preferably 1:1 to 1:2.

[0028] Furthermore, the concentration of phenol after dissolving in the solvent is 2 mol / L to 10 mol / L, preferably 3 mol / L to 5 mol / L.

[0029] It should be noted that an air atmosphere or an inert atmosphere is used to protect phenol and metal sources during the dissolution or dispersion process.

[0030] As a specific embodiment of the present invention, solvent removal can be carried out by heating, spray drying, flash evaporation or freeze drying, and an air atmosphere or inert atmosphere is used for protection during the solvent removal process.

[0031] In another specific embodiment of the present invention, in S1, the preparation method of the phenol metal salt includes the following steps: adding phenol and a metal source into a solvent, reacting, removing the solvent, and obtaining the phenol metal salt; wherein, the metal salt includes one or more of the elements or metal hydrides of lithium, sodium, potassium, magnesium, calcium, zinc, manganese, aluminum, and iron.

[0032] Furthermore, the solvent mentioned above is water or an alcohol, such as anhydrous ethanol or methanol.

[0033] Furthermore, the molar ratio of the phenol to the metal element in the metal source is 1:1 to 1:3.

[0034] Furthermore, the above reaction is a room temperature reaction, and the reaction time is not less than 0.5 h.

[0035] As a specific embodiment of the present invention, solvent removal can be carried out by heating, spray drying, flash evaporation or freeze drying, and an air atmosphere or inert atmosphere is used for protection during the solvent removal process.

[0036] In another specific embodiment of the present invention, in S1, the method for preparing the phenol metal salt includes the following steps: reacting molten phenol with a solid metal source in an air atmosphere or an inert atmosphere to obtain the phenol metal salt; wherein, the solid metal source includes one or more of the metal oxides or hydroxides corresponding to lithium, sodium, potassium, magnesium, calcium, zinc, manganese, aluminum, and iron.

[0037] Furthermore, the temperature of the above reaction is 45℃~150℃, and the reaction time is not less than 0.5h.

[0038] Furthermore, the molar ratio of the phenol to the metal element in the metal source is 1:1 to 1:3.

[0039] The methods for preparing phenol metal salts listed above are just a few specific feasible methods. This invention includes, but is not limited to, the above methods.

[0040] Furthermore, in S3, the pickling process uses one or more of the following: hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, hydrobromic acid, phosphoric acid, perchloric acid, formic acid, or acetic acid.

[0041] Further, in S4, the temperature is increased to 700°C to 1200°C at a rate of 2°C / min to 25°C / min, preferably at a rate of 5°C / min to 10°C / min.

[0042] Furthermore, in S4, the calcination temperature is 800℃~1000℃, and the calcination time is 1h~2h.

[0043] Furthermore, in S4, the protective atmosphere gas is one or more of nitrogen, argon, helium, carbon dioxide, or water vapor.

[0044] It should be noted that in S4, the oxygen content in the porous carbon can be tested using an organic elemental analyzer.

[0045] Furthermore, in S5, the porous carbon has a D0 of 2μm to 4μm, a D50 of 5μm to 10μm, and a D100 of 10μm to 20μm.

[0046] Furthermore, in S5, the specific surface area of ​​the porous carbon is 1500 m². 2 / g~2000m 2 / g, total pore volume is 0.8cm³ 3 / g~1.2cm 3 / g, the proportion of micropore volume to total pore volume is 85% to 95%, and the average pore size is 1.7nm to 2.5nm.

[0047] Secondly, the present invention also provides a porous carbon, which is prepared by the above-described method for preparing porous carbon.

[0048] Thirdly, the present invention also provides a silicon-carbon material, comprising the aforementioned porous carbon.

[0049] Fourthly, the present invention also provides a method for preparing silicon-carbon materials, comprising the following steps:

[0050] Step a: Silicon particles are deposited onto the surface and / or pores of the porous carbon by chemical vapor deposition to obtain a silicon-carbon material precursor;

[0051] Step b involves performing one-step or two-step carbon coating on the silicon-carbon material precursor to obtain a silicon-carbon material.

[0052] The method for preparing porous carbon provided by this invention uses phenol metal salt as a carbon source. Compared with metal salts of other organic acids (such as gluconic acid, citric acid, or benzoic acid), phenol metal salt has a higher carbon retention rate, which can improve the yield of porous carbon. In addition, the metal oxide formed by the metal ions and phenol hydroxyl groups is equivalent to an in-situ embedded alkaline pore-forming agent. It can be uniformly distributed during the carbonization process and play a role in activating pore formation. Due to the blockage of the carbon material, the metal oxide cannot continue to grow during the carbonization process, thus forming extremely small nanoparticles. After the metal oxide is removed during the carbonization or acid washing process, a highly ordered pore structure dominated by micropores is formed in the porous carbon. The highly ordered pore size distribution avoids the adverse effects of ultra-micropores that cannot deposit silicon and large mesopores that over-deposit silicon on the electrochemical performance of silicon-carbon anodes. Furthermore, the particle size distribution of the graded porous carbon is within a suitable range, thus enabling silicon-carbon materials prepared based on it to have advantages such as high compaction, high initial efficiency, high rate capability, and long cycle life. This provides a high-performance anode material for lithium-ion batteries and has high practical value.

[0053] As a specific embodiment of the present invention, the method for preparing the silicon-carbon material specifically includes the following steps:

[0054] Step a: Place porous carbon in a vapor deposition silicon equipment, introduce inert gas to remove oxygen from the equipment, heat to 450℃~700℃, introduce silicon source gas, react for 2h~6h, stop the introduction of silicon source gas, adjust the temperature to 500℃~750℃, introduce carbon source gas, react for 1h~5h, stop the introduction of carbon source gas, and then cool down in an inert atmosphere to obtain a silicon-carbon material with primary carbon coating.

[0055] Step b: Place the primary carbon-coated silicon-carbon material in a carbon coating device, introduce an inert gas to purge oxygen, heat to 500℃~750℃, introduce a carbon source gas, react for 1h~5h, then stop the introduction of the carbon source gas, and then cool in an inert atmosphere to obtain a secondary carbon-coated silicon-carbon material.

[0056] Further, in step a, the inert gas is one or more of nitrogen, argon, helium, or carbon dioxide.

[0057] Further, in step a, the silicon source gas is one or more of silane, disilane, dichlorosilane, or trichlorosilane.

[0058] Preferably, in step a, the silicon source gas is silane or ethylsilane.

[0059] Furthermore, in step a, the temperature at which the silicon source gas is introduced is 500℃~600℃, and the reaction time is 3h~5h.

[0060] Furthermore, in step a, a programmed temperature rise method is adopted, with a heating rate of 2℃ / min to 25℃ / min, preferably 5℃ / min to 10℃ / min.

[0061] Further, in step a, the flow rate of the silicon source gas is 1L / min to 5L / min.

[0062] Preferably, in step a, the flow rate of the silicon source gas is 2L / min to 4L / min.

[0063] Further, in step a, the carbon source gas is one or more of methane, ethane, propane, butane, ethylene, propylene, acetylene, or propyne.

[0064] Preferably, in step a, the carbon source gas is ethylene or acetylene.

[0065] Further, in step a, the flow rate of the carbon source gas is 1 L / min to 4 L / min.

[0066] Preferably, in step a, the flow rate of the carbon source gas is 2 L / min to 3 L / min.

[0067] Furthermore, the temperature of the carbon source gas is 600℃~700℃, and the reaction time is 2h~3h. Furthermore, in step a, the flow rate of the inert gas is 5L / min~30L / min.

[0068] Preferably, in step a, the inert gas flow rate is 10 L / min to 20 L / min.

[0069] Further, in step b, the carbon source gas is one or more of methane, ethane, propane, butane, ethylene, propylene, ethylene, or propyne.

[0070] Preferably, in step b, the carbon source gas is ethylene or acetylene.

[0071] Furthermore, in step b, the flow rate of the carbon source gas is 1 L / min to 4 L / min.

[0072] Preferably, in step b, the flow rate of the carbon source gas is 2 L / min to 3 L / min.

[0073] Furthermore, in step b, the inert gas flow rate is 5 L / min to 30 L / min.

[0074] Preferably, in step b, the inert gas flow rate is 10 L / min to 20 L / min.

[0075] Furthermore, in step b, a programmed temperature rise method is adopted, with a heating rate of 2℃ / min to 25℃ / min, preferably 5℃ / min to 10℃ / min.

[0076] It should be noted that in step b, the secondary carbon coating is not limited to using a gaseous carbon source. A solid carbon source (such as solid asphalt, glucose, sucrose, cyclodextrin, citric acid, carbon nanotubes, graphene, Ketjen black, acetylene black, etc.) or a liquid carbon source (such as liquid asphalt, methanol, ethanol, etc.) can also be mixed uniformly with the silicon-carbon material undergoing primary carbon coating in step a, followed by heat treatment to obtain the secondary-coated silicon-carbon material. The heating rate, holding temperature, and inert atmosphere flow rate for heat treatment using a solid or liquid carbon source are the same as in step b, and the amount of solid or liquid carbon source added is 1% to 10% of the mass of the silicon-carbon material undergoing primary carbon coating in step a.

[0077] Fifthly, the present invention also provides a negative electrode comprising the aforementioned silicon-carbon material.

[0078] In a sixth aspect, the present invention also provides the application of the above-mentioned silicon-carbon material or the above-mentioned negative electrode in the preparation of lithium-ion batteries.

[0079] In a seventh aspect, the present invention also provides a lithium-ion battery comprising the aforementioned silicon-carbon material or the aforementioned negative electrode.

[0080] Eighthly, the present invention also provides a battery module including the lithium-ion battery described above.

[0081] The porous carbon prepared by this invention has advantages such as high microporosity and high uniformity and order of pore size. When used for further preparation of silicon-carbon materials by chemical vapor deposition, the diffusion resistance of silane gas inside the porous carbon material is smaller, which is beneficial to improving silicon deposition efficiency. At the same time, it is also beneficial to the uniform dispersion and fixation of silicon particles in the porous carbon channel structure, avoiding the aggregation of silicon particles. Moreover, the limiting effect of micropore size can effectively control the nucleation and growth of silicon particles, thereby preparing silicon particles with uniform size. The uniformly distributed silicon particles and the ordered channel structure are beneficial to improving the conductivity and ion diffusion rate of silicon-carbon materials. In addition, the ordered channel structure of porous carbon can buffer the volume change of silicon during charge and discharge, improving the cycle stability and service life of silicon-carbon materials. Applying the above-mentioned silicon-carbon material to lithium-ion batteries helps to improve the electrochemical performance of electrochemical devices containing this silicon-carbon anode material. Attached Figure Description

[0082] Figure 1 This is a schematic diagram of the process for preparing porous carbon materials in Example 1 of the present invention. Detailed Implementation

[0083] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0084] To better illustrate the present invention, further examples are provided below.

[0085] Example 1

[0086] This embodiment provides a method for preparing porous carbon materials, which specifically includes the following steps:

[0087] S1, Under a nitrogen atmosphere, phenol and sodium hydroxide are dissolved in water at a molar ratio of 1:1, wherein the concentration of phenol is 3 mol / L. The above solution is heated under a nitrogen atmosphere to remove water, thereby obtaining sodium phenolate.

[0088] S2, Under a nitrogen atmosphere, the sodium phenolate prepared above was heated to 800°C at a rate of 5°C / min, held at that temperature for 3 hours, and then cooled to room temperature to obtain a composite material of carbon material and metal derivative.

[0089] S3, the above composite material is crushed to a D50 of 7μm, and its ash content is tested to be >0.2%. The crushed composite material is then acid-washed with hydrochloric acid and water until the pH of the water washing solution is 6.1. The porous carbon is collected and dried.

[0090] S4, the oxygen content of the dried porous carbon was tested to be >5 mmol / g. The dried porous carbon was heated to 900℃ at a rate of 5℃ / min under a nitrogen atmosphere and held for 1.5h to obtain deoxygenated porous carbon.

[0091] S5. The above-mentioned deoxidized porous carbon is crushed and graded to obtain finished porous carbon with D0 of 2μm, D50 of 7μm and D100 of 18μm. After standing in air at room temperature, normal pressure and humidity of 50% for 3 days, its moisture content is 2.5%.

[0092] Example 2

[0093] This embodiment provides a method for preparing porous carbon materials, which specifically includes the following steps:

[0094] S1, Under a nitrogen atmosphere, phenol and zinc oxide are dissolved in water at a molar ratio of 1:1.5, wherein the concentration of phenol is 4 mol / L. The above solution is heated under a nitrogen atmosphere to remove water, yielding zinc phenol.

[0095] S2, Under a nitrogen atmosphere, the zinc phenol prepared above was heated to 900°C at a rate of 7°C / min, held at that temperature for 4 hours, and then cooled to room temperature to obtain a composite material of carbon material and metal derivative.

[0096] S3, the above composite material is crushed to D50 of 5μm, and its ash content is tested to be >0.2%. The crushed composite material is then acid-washed with hydrochloric acid and water until the pH of the water washing solution is 6.8. The porous carbon is collected and dried.

[0097] S4, the oxygen content of the dried porous carbon is >5 mmol / g. The dried porous carbon is heated to 1000℃ at a rate of 10℃ / min under a nitrogen atmosphere and held for 1h to obtain deoxygenated porous carbon.

[0098] S5. The above-mentioned deoxidized porous carbon is crushed and graded to obtain finished porous carbon with D0 of 4μm, D50 of 5μm and D100 of 10μm. After standing in air at room temperature, normal pressure and humidity of 50% for 3 days, its moisture content is 2.1%.

[0099] Example 3

[0100] This embodiment provides a method for preparing porous carbon materials, which specifically includes the following steps:

[0101] S1, Under a nitrogen atmosphere, phenol and manganese hydroxide are dispersed in water at a molar ratio of 1:2.5, wherein the concentration of phenol is 5 mol / L. The above solution is spray-dried under a nitrogen atmosphere to obtain manganese phenol.

[0102] S2, Under a nitrogen atmosphere, the phenol manganese prepared above was heated to 1000℃ at a rate of 8℃ / min, held at that temperature for 2h, and then cooled to room temperature to obtain a composite material of carbon material and metal derivative.

[0103] S3, the above composite material is crushed to D50 of 10μm, and its ash content is tested to be >0.2%. The crushed composite material is then acid-washed with hydrochloric acid and water until the pH of the water washing solution is 6.6. The porous carbon is collected and dried.

[0104] S4, the oxygen content of the dried porous carbon is >5 mmol / g. The dried porous carbon is heated to 800℃ at a rate of 6℃ / min under a nitrogen atmosphere and held for 2h to obtain deoxygenated porous carbon.

[0105] S5. The above-mentioned deoxidized porous carbon is crushed and graded to obtain finished porous carbon with D0 of 3μm, D50 of 10μm and D100 of 20μm. After standing in air at room temperature, normal pressure and humidity of 50% for 3 days, its moisture content is 2.0%.

[0106] Example 4

[0107] This embodiment provides a method for preparing porous carbon materials, which specifically includes the following steps:

[0108] S1, Under a nitrogen atmosphere, phenol and calcium oxide are dissolved in water at a molar ratio of 1:3, wherein the concentration of phenol is 2 mol / L. The above solution is then flash-evaporated under a nitrogen atmosphere to obtain calcium phenolate.

[0109] S2, Under a nitrogen atmosphere, the phenolic calcium prepared above was heated to 600°C at a rate of 2°C / min, held at that temperature for 5 hours, and then cooled to room temperature to obtain a composite material of carbon material and metal derivative.

[0110] S3, the above composite material is crushed to D50 of 3μm, and its ash content is tested to be >0.2%. The crushed composite material is then acid-washed with hydrochloric acid and water until the pH of the water washing solution is 6.1. The porous carbon is collected and dried.

[0111] S4, the oxygen content of the dried porous carbon is >5 mmol / g. The dried porous carbon is heated to 700℃ at a rate of 2℃ / min under a nitrogen atmosphere and held for 3h to obtain deoxygenated porous carbon.

[0112] S5. The above-mentioned deoxidized porous carbon is crushed and graded to obtain finished porous carbon with D0 of 1μm, D50 of 3μm and D100 of 15μm. After standing in air at room temperature, normal pressure and humidity of 50% for 3 days, its moisture content is 2.7%.

[0113] Example 5

[0114] This embodiment provides a method for preparing porous carbon materials, which specifically includes the following steps:

[0115] S1, Under a nitrogen atmosphere, phenol and sodium oxide are dissolved in water at a mol:1 ratio, wherein the concentration of phenol is 10 mol / L. The above solution is freeze-dried under a nitrogen atmosphere to obtain sodium phenolate.

[0116] S2, Under a nitrogen atmosphere, the sodium phenolate prepared above was heated to 1100°C at a rate of 25°C / min, held at that temperature for 1 hour, and then cooled to room temperature to obtain a composite material of carbon material and metal derivative.

[0117] S3, the above composite material is crushed to D50 of 15μm, and its ash content is tested to be >0.2%. The crushed composite material is then acid-washed with hydrochloric acid and water until the pH of the water washing solution is 6.3. The porous carbon is collected and dried.

[0118] S4, the oxygen content of the dried porous carbon was tested to be >5 mmol / g. The dried porous carbon was heated to 1200℃ at a rate of 25℃ / min under a nitrogen atmosphere and held for 0.5h to obtain deoxygenated porous carbon.

[0119] S5. The above-mentioned deoxidized porous carbon is crushed and graded to obtain finished porous carbon with D0 of 5μm, D50 of 15μm and D100 of 30μm. After standing in air at room temperature, normal pressure and humidity of 50% for 3 days, its moisture content is 1.8%.

[0120] Example 6

[0121] This embodiment provides a method for preparing porous carbon materials, which specifically includes the following steps:

[0122] S1, Under a nitrogen atmosphere, phenol and potassium hydroxide are dissolved in water at a mol / L ratio of 1:2, wherein the concentration of phenol is 6 mol / L. The above solution is spray-dried under a nitrogen atmosphere to obtain potassium phenolate.

[0123] S2, Under a nitrogen atmosphere, the potassium phenolate prepared above was heated to 950°C at a rate of 10°C / min, held at that temperature for 4 hours, and then cooled to room temperature to obtain a composite material of carbon material and metal derivative.

[0124] S3, the above composite material is crushed to a D50 of 7μm, and its ash content is tested to be >0.2%. The crushed composite material is then acid-washed with hydrochloric acid and water until the pH of the water washing solution is 6.5. The porous carbon is collected and dried.

[0125] S4, the oxygen content of the dried porous carbon was tested to be >5 mmol / g. The dried porous carbon was heated to 850℃ at a rate of 7℃ / min under a nitrogen atmosphere and held for 2h to obtain deoxygenated porous carbon.

[0126] S5. The above-mentioned deoxidized porous carbon is crushed and graded to obtain finished porous carbon with D0 of 3μm, D50 of 7μm and D100 of 18μm. After standing in air at room temperature, normal pressure and humidity of 50% for 3 days, its moisture content is 2.4%.

[0127] Example 7

[0128] This embodiment provides a method for preparing silicon-carbon materials, including the following steps:

[0129] Step a: Weigh 1.5385 kg of the porous carbon prepared in Example 1, i.e., the mass of the dried and anhydrous porous carbon is 1.5 kg, transfer it to the vapor deposition silicon equipment, introduce nitrogen gas at a flow rate of 30 L / min (the nitrogen flow rate is maintained until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then heat to 550°C at a rate of 5°C / min and introduce silane at a flow rate of 2 L / min for 5 h, stop introducing silane, and then heat to 600°C at a rate of 5°C / min and start introducing acetylene at a flow rate of 2 L / min for 3 h, stop introducing acetylene, and allow it to cool naturally to room temperature to obtain a silicon-carbon material with one-time carbon coating;

[0130] Step b: Transfer the primary carbon-coated silicon-carbon material prepared above to a secondary carbon-coating device, introduce nitrogen gas at a flow rate of 10 L / min (maintain the nitrogen flow rate until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then heat to 600°C at a rate of 5°C / min and start introducing acetylene at a flow rate of 2 L / min for 3 hours. Stop introducing acetylene and allow the material to cool naturally to room temperature to obtain the secondary carbon-coated silicon-carbon material.

[0131] Example 8

[0132] This embodiment provides a method for preparing silicon-carbon materials, including the following steps:

[0133] Step a: Weigh 1.5322 kg of the porous carbon prepared in Example 2, i.e., the mass of the dried and anhydrous porous carbon is 1.5 kg, transfer it to the silicon vapor deposition equipment, introduce nitrogen gas at a flow rate of 10 L / min (the nitrogen flow rate is maintained until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then heat to 600°C at a rate of 10°C / min and introduce silane at a flow rate of 3 L / min for 3 h, stop introducing silane, and then heat to 700°C at a rate of 10°C / min and start introducing acetylene at a flow rate of 4 L / min for 2 h, stop introducing acetylene, and allow it to cool naturally to room temperature to obtain a silicon-carbon material with one-time carbon coating;

[0134] Step b: Transfer the primary carbon-coated silicon-carbon material prepared above to a secondary carbon-coating device, introduce nitrogen gas at a flow rate of 15 L / min (maintain the nitrogen flow rate until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then heat to 700°C at a rate of 10°C / min and start introducing acetylene at a flow rate of 4 L / min for 2 hours. Stop introducing acetylene and allow the material to cool naturally to room temperature to obtain the secondary carbon-coated silicon-carbon material.

[0135] Example 9

[0136] This embodiment provides a method for preparing silicon-carbon materials, including the following steps:

[0137] Step a: Weigh 1.5306 kg of the porous carbon prepared in Example 3, i.e., the mass of the dried and anhydrous porous carbon is 1.5 kg, transfer it to the silicon vapor deposition equipment, introduce nitrogen gas at a flow rate of 20 L / min (the nitrogen flow rate is maintained until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then heat to 500°C at a rate of 8°C / min and introduce silane at a flow rate of 4 L / min for 4 h, stop introducing silane, and then heat to 600°C at a rate of 8°C / min and start introducing acetylene at a flow rate of 3 L / min for 4 h, stop introducing acetylene, and allow it to cool naturally to room temperature to obtain a silicon-carbon material with one-time carbon coating;

[0138] Step b: Transfer the primary carbon-coated silicon-carbon material prepared above to a secondary carbon-coating device, introduce nitrogen gas at a flow rate of 20 L / min (maintain the nitrogen flow rate until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then raise the temperature to 600°C at a rate of 8°C / min and start introducing acetylene at a flow rate of 3 L / min for 4 hours. Stop introducing acetylene and allow the material to cool naturally to room temperature to obtain the secondary carbon-coated silicon-carbon material.

[0139] Example 10

[0140] This embodiment provides a method for preparing silicon-carbon materials, including the following steps:

[0141] Step a: Weigh 1.5416 kg of the porous carbon prepared in Example 4, i.e., the mass of the dried and anhydrous porous carbon is 1.5 kg, transfer it to the silicon vapor deposition equipment, introduce nitrogen gas at a flow rate of 5 L / min (the nitrogen flow rate is maintained until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then heat to 450°C at a rate of 2°C / min and introduce silane at a flow rate of 1 L / min for 6 h. Stop introducing silane and heat to 500°C at a rate of 2°C / min. Then start introducing acetylene at a flow rate of 4 L / min for 1 h. Stop introducing acetylene and allow it to cool naturally to room temperature to obtain a silicon-carbon material with one-time carbon coating.

[0142] Step b: Transfer the primary carbon-coated silicon-carbon material prepared above to a secondary carbon-coating device, introduce nitrogen gas at a flow rate of 5 L / min (maintain the nitrogen flow rate until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then heat to 500°C at a rate of 2°C / min and start introducing acetylene at a flow rate of 4 L / min for 1 hour. Stop introducing acetylene and allow the material to cool naturally to room temperature to obtain the secondary carbon-coated silicon-carbon material.

[0143] Example 11

[0144] This embodiment provides a method for preparing silicon-carbon materials, including the following steps:

[0145] Step a: Weigh 1.5275 kg of the porous carbon prepared in Example 5, i.e., the mass of the dried and anhydrous porous carbon is 1.5 kg, transfer it to the silicon vapor deposition equipment, introduce nitrogen gas at a flow rate of 15 L / min (the nitrogen flow rate is maintained until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then heat to 700°C at a rate of 25°C / min and introduce silane at a flow rate of 5 L / min for 2 h, stop introducing silane, and then heat to 750°C at a rate of 25°C / min and start introducing acetylene at a flow rate of 1 L / min for 5 h, stop introducing acetylene, and allow it to cool naturally to room temperature to obtain a silicon-carbon material with one-time carbon coating;

[0146] Step b: Transfer the primary carbon-coated silicon-carbon material prepared above to a secondary carbon-coating device, introduce nitrogen gas at a flow rate of 30 L / min (maintain the nitrogen flow rate until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then raise the temperature to 750°C at a rate of 25°C / min and start introducing acetylene at a flow rate of 1 L / min for 5 hours. Stop introducing acetylene and allow the material to cool naturally to room temperature to obtain the secondary carbon-coated silicon-carbon material.

[0147] Example 12

[0148] This embodiment provides a method for preparing silicon-carbon materials, including the following steps:

[0149] Step a: Weigh 1.5369 kg of the porous carbon prepared in Example 6, i.e., the mass of the dried and anhydrous porous carbon is 1.5 kg, transfer it to the silicon vapor deposition equipment, introduce nitrogen gas at a flow rate of 25 L / min (the nitrogen flow rate is maintained until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then heat to 550°C at a rate of 15°C / min and introduce silane at a flow rate of 3 L / min for 4 h, stop introducing silane, and then heat to 650°C at a rate of 5°C / min and start introducing acetylene at a flow rate of 3 L / min for 2 h, stop introducing acetylene, and allow it to cool naturally to room temperature to obtain a silicon-carbon material with one-time carbon coating;

[0150] Step b: Transfer the primary carbon-coated silicon-carbon material prepared above to a secondary carbon-coating device, introduce nitrogen gas at a flow rate of 15 L / min (maintain the nitrogen flow rate until the temperature drops to room temperature), remove oxygen until the oxygen content is below 0.5%, then heat to 650°C at a rate of 5°C / min and start introducing acetylene at a flow rate of 3 L / min for 2 hours. Stop introducing acetylene and allow the material to cool naturally to room temperature to obtain the secondary carbon-coated silicon-carbon material.

[0151] Comparative Example 1

[0152] This comparative example provides a method for preparing porous carbon, comprising the following steps:

[0153] Step a: pulverize coconut shell charcoal to a D50 of 8 μm, mix it with potassium hydroxide at a mass ratio of 1:1, heat the resulting mixture to 850°C at a rate of 5°C / min under a nitrogen atmosphere and hold for 3 hours, then cool to room temperature to obtain a composite material of carbon material and metal derivative.

[0154] Step b: The above composite material is acid-washed and water-washed until the pH of the water washing solution is 6. The porous carbon is then filtered, collected, and dried. The dried porous carbon is heated to 900°C at a rate of 5°C / min under a nitrogen atmosphere and held for 3 hours to obtain deoxidized porous carbon.

[0155] Step c involves classifying the deoxidized porous carbon to obtain finished porous carbon with D0 of 2 μm, D50 of 7 μm, and D100 of 18 μm.

[0156] The porous carbon product prepared above was used to prepare silicon-carbon material in the same way as in Example 7.

[0157] Comparative Example 2

[0158] This comparative example provides a method for preparing porous carbon, comprising the following steps:

[0159] Step a: Phenolic resin carbonized material (phenolic resin powder is kept at 600℃ for 3h under nitrogen atmosphere) is pulverized to D50 of 8μm, and mixed with potassium hydroxide at a mass ratio of 1:1. The resulting mixture is heated to 850℃ at a rate of 5℃ / min under nitrogen atmosphere and kept at that temperature for 3h, and then cooled to room temperature to obtain carbon material and metal derivative composite material.

[0160] Step b: The above composite material is acid-washed and water-washed until the pH of the water washing solution is 6. The porous carbon is then filtered, collected, and dried. The dried porous carbon is heated to 900°C at a rate of 5°C / min under a nitrogen atmosphere and held for 3 hours to obtain deoxidized porous carbon.

[0161] Step c involves classifying the deoxidized porous carbon to obtain finished porous carbon with D0 of 2 μm, D50 of 7 μm, and D100 of 18 μm.

[0162] The porous carbon product prepared above was used to prepare silicon-carbon material in the same way as in Example 7.

[0163] Comparative Example 3

[0164] This comparative example provides a method for preparing porous carbon, comprising the following steps:

[0165] Step a: Crush petroleum coke to a D50 of 8 μm, mix it with potassium hydroxide at a mass ratio of 1:1, heat the resulting mixture to 850°C at a rate of 5°C / min under a nitrogen atmosphere and hold for 3 hours, then cool to room temperature to obtain a composite material of carbon materials and metal derivatives.

[0166] Step b: The above composite material is acid-washed and water-washed until the pH of the water washing solution is 6. The porous carbon is then filtered, collected, and dried. The dried porous carbon is heated to 900°C at a rate of 5°C / min under a nitrogen atmosphere and held for 3 hours to obtain deoxidized porous carbon.

[0167] Step c involves classifying the deoxidized porous carbon to obtain finished porous carbon with D0 of 2 μm, D50 of 7 μm, and D100 of 18 μm.

[0168] The porous carbon product prepared above was used to prepare silicon-carbon material in the same way as in Example 7.

[0169] Comparative Example 4

[0170] This comparative example provides a method for preparing porous carbon, comprising the following steps:

[0171] S1, Under a nitrogen atmosphere, sodium gluconate is dissolved in water, wherein the concentration of sodium gluconate is 3 mol / L. The above solution is heated under a nitrogen atmosphere to remove water, thereby obtaining sodium gluconate.

[0172] S2 to S5 are the same as in Example 1, and will not be described again here.

[0173] The porous carbon product prepared above was used to prepare silicon-carbon material in the same way as in Example 7.

[0174] Comparative Example 5

[0175] This comparative example provides a method for preparing porous carbon, comprising the following steps:

[0176] S1, Sodium citrate is dissolved in water under a nitrogen atmosphere, wherein the concentration of sodium citrate is 3 mol / L. The solution is then heated under a nitrogen atmosphere to remove water, thereby obtaining sodium citrate.

[0177] S2 to S5 are the same as in Example 1, and will not be described again here.

[0178] The porous carbon product prepared above was used to prepare silicon-carbon material in the same way as in Example 7.

[0179] Comparative Example 6

[0180] This comparative example provides a method for preparing porous carbon, comprising the following steps:

[0181] S1, Sodium benzoate is dissolved in water under a nitrogen atmosphere, wherein the concentration of sodium benzoate is 3 mol / L. The above solution is heated under a nitrogen atmosphere to remove water, thereby obtaining sodium benzoate.

[0182] S2 to S5 are the same as in Example 1, and will not be described again here.

[0183] The porous carbon product prepared above was used to prepare silicon-carbon material in the same way as in Example 7.

[0184] Comparative Example 7

[0185] This comparative example provides a method for preparing porous carbon, comprising the following steps:

[0186] S1 to S4 are the same as in Example 1, and will not be described again here;

[0187] S5, the above-mentioned deoxidized porous carbon is crushed and classified to obtain finished porous carbon with D0 of 0.2μm, D50 of 7μm and D100 of 18μm.

[0188] Comparative Example 8

[0189] This comparative example provides a method for preparing porous carbon, comprising the following steps:

[0190] S1 to S4 are the same as in Example 1, and will not be described again here;

[0191] S5, the above-mentioned deoxidized porous carbon is crushed and classified to obtain finished porous carbon with D0 of 2μm, D50 of 7μm and D100 of 40μm.

[0192] The porous carbons prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were characterized, and the results are shown in Table 1.

[0193] Table 1

[0194]

[0195] Application Examples

[0196] The silicon-carbon materials prepared in Examples 7 to 12 and Comparative Examples 1 to 8 were assembled into batteries, and the specific steps are as follows:

[0197] (1) Preparation of negative electrode sheet: 2.5g of N-methylpyrrolidone and 0.1g of polyvinylidene fluoride were mixed evenly to obtain a transparent viscous solution. Then, 0.1g of conductive carbon black Super P was added and dispersed evenly. 0.8g of negative electrode material was added and dispersed evenly to obtain a black viscous slurry. The negative electrode material was a mixture of silicon carbon material and graphite material (1.5V charging specific capacity 355mAh / g, initial coulombic efficiency 93.6%) (mass ratio of the two is 1:9). The black viscous slurry was uniformly coated on the surface of copper foil with a coating thickness of 100μm using a scraper. After drying at 90℃, it was rolled and cut into round sheets with a diameter of 14mm and weighed for later use.

[0198] (2) Assembly of lithium-ion batteries: A 15.8 mm diameter, 100 μm thick lithium metal sheet was used as the counter electrode, a 16 mm diameter, 25 μm thick Celgard 2400 separator was used as the separator, and the aforementioned 14 mm diameter negative electrode sheet was used as the working electrode. A 1 mol / L solution of LiPF6 dissolved in ethylene carbonate and methyl ethyl carbonate (volume ratio 3:7) was used as the electrolyte to assemble 2032 type button batteries. Six batteries were assembled for each type of negative electrode material, and a total of six sets of data were tested. After removing the highest and lowest data, the average of the remaining four sets of data was taken as the battery performance data.

[0199] (3) The specific test conditions for the button cell performance are as follows: At room temperature of 25℃, using a Blue Electricity tester, the assembled button cell is discharged to 0.005V at 0.1C (1C corresponds to 450mAh / g), left to stand for 5 minutes, then discharged to 0.005V at 0.05C, left to stand for another 5 minutes, and then discharged to 0.005V at 0.02C to end the discharge program. After leaving to stand for 5 minutes, it is charged to 1.5V at 0.1C. The ratio of the charging specific capacity to the discharging specific capacity is the first coulombic efficiency at 1.5V. Furthermore, the battery is discharged to 0.005V at 0.2C, left to stand for 5 minutes, then discharged to 0.005V at 0.05C, left to stand for 5 minutes, and then charged to 1.5V at 0.2C. The ratio of the charging specific capacity after 50 cycles to the charging specific capacity of the first cycle (the first charge at 0.2C) is the capacity retention rate. On the other hand, the first-cycle full-charge expansion rate was obtained by measuring the ratio of the electrode thickness after the first charge cycle (thickness after removing the copper foil) to the electrode thickness before the cycle (thickness after removing the copper foil). The results are shown in Table 2.

[0200] Table 2

[0201]

[0202]

[0203] The results show that the lithium-ion batteries with added silicon-carbon materials prepared in Examples 7 to 12 of this invention have better charging specific capacity, charging coulombic efficiency, capacity retention rate, and first-cycle full-charge expansion rate than comparative examples 1 to 8. This proves that using silicon-carbon materials prepared with porous carbon provided by this invention as negative electrode materials can significantly improve the electrochemical performance and cycle life of lithium-ion batteries, which is of great significance to the development of lithium-ion batteries.

[0204] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing porous carbon, characterized in that, Includes the following steps: S1, Under a protective atmosphere, phenol metal salt is calcined at 600℃~1100℃ for 1h~5h to obtain carbon-based materials; S2, the carbon-based material is pulverized to make its D50 3μm~15μm; S3, the ash content of the pulverized carbon-based material is tested. If the ash content is ≤0.2%, proceed directly to S4; if the ash content is >0.2%, the pulverized carbon-based material is subjected to several acid washing and water washing processes until the ash content of the carbon-based material is ≤0.2% or the pH of the washing solution is <7. S4. Test the oxygen content of the pulverized carbon material. If the oxygen content is ≤0.05mmol / g, proceed directly to S5. If the oxygen content is >0.05mmol / g, calcine the pulverized carbon material at 700℃~1200℃ for 0.5h~3h under a protective atmosphere before proceeding to S5. S5, test the particle size of the carbon material in S4. If it meets the requirements of D0 being 1μm~5μm, D50 being 3μm~15μm, and D100 being 10μm~30μm, then no further processing is required. If it does not meet the above particle size requirements, then the carbon material is crushed and graded until the particle size meets the requirements to obtain porous carbon. In S1, the preparation method of the phenol metal salt includes the following steps: adding phenol and a metal source to a solvent, mixing them evenly, removing the solvent, and obtaining the phenol metal salt; wherein, the metal source includes one or more of the metal oxides or hydroxides corresponding to lithium, sodium, potassium, magnesium, calcium, zinc, manganese, aluminum, and iron. or In S1, the preparation method of the phenol metal salt includes the following steps: adding phenol and a metal source to a solvent, reacting, removing the solvent, and obtaining the phenol metal salt; wherein the metal salt includes one or more of the elements or metal hydrides of lithium, sodium, potassium, magnesium, calcium, zinc, manganese, aluminum, and iron.

2. The method for preparing porous carbon as described in claim 1, characterized in that, In S1 and S4, the protective atmosphere gas is one or more of nitrogen, argon, helium, carbon dioxide, or water vapor; and / or In S1, the temperature is increased to 600℃~1100℃ at a rate of 2℃ / min~25℃ / min; and / or In S1, the phenol metal salt is one or more of lithium phenolate, sodium phenolate, potassium phenolate, magnesium phenolate, calcium phenolate, zinc phenolate, manganese phenolate, aluminum phenolate, or iron phenolate; and / or In S3, the pickling process uses one or more of the following: hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, hydrobromic acid, phosphoric acid, perchloric acid, formic acid, or acetic acid; and / or In S4, the temperature is increased to 700℃~1200℃ at a rate of 2℃ / min~25℃ / min.

3. A porous carbon, characterized in that, It is prepared by the method for preparing porous carbon according to claim 1 or 2.

4. A silicon-carbon material, characterized in that, Includes the porous carbon as described in claim 3.

5. A method for preparing the silicon-carbon material according to claim 4, characterized in that, Includes the following steps: Step a: Silicon particles are deposited onto the surface and / or pores of the porous carbon by chemical vapor deposition to obtain a silicon-carbon material precursor; Step b involves performing one-step or two-step carbon coating on the silicon-carbon material precursor to obtain a silicon-carbon material.

6. A negative electrode, characterized in that, Including the silicon-carbon material as described in claim 4.

7. The application of the silicon-carbon material of claim 4 or the negative electrode of claim 6 in the preparation of lithium-ion batteries.

8. A lithium-ion battery, characterized in that, Includes the silicon-carbon material as described in claim 4 or the negative electrode as described in claim 6.

9. A battery module, characterized in that, Including the lithium-ion battery as described in claim 8.

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