Negative electrode material and method for manufacturing the same, lithium-ion battery

Abstract

This application relates to a negative electrode material, a method for manufacturing the same, and a lithium-ion battery. The negative electrode material includes an active material. The active material includes a porous matrix and a silicon matrix, at least a portion of which is distributed within the pores of the porous matrix. The infrared spectrum obtained by measuring the negative electrode material using an infrared spectrometer has a wavenumber of 2090 cm⁻¹. -1 The stretching vibration peak and wavenumber of the SiH2 bond are 2000 cm. -1 There are stretching vibration peaks for SiH bonds. The ratio Z of the vibration peak area of ​​SiH2 bonds to the vibration peak area of ​​SiH bonds in the anode material is 0.01 to 5.0. Within the above limited range, the silicon matrix in the anode material according to the present invention mainly exists in the form of SiH bonds, and it has become clear that the stability of SiH bonds is greater than that of SiH2 bonds, and that a silicon matrix with many SiH bonds contributes to improving the structural stability of the anode material and the mechanical performance of the silicon matrix, reduces the occurrence of side reactions between the anode material and the electrolyte, and further improves the cycle performance and expansion performance of the anode material.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority to the Chinese patent application No. 202311280138.7, filed with the National Intellectual Property Administration on September 28, 2023, with the application title "Anode material and method for manufacturing the same, lithium-ion battery," the entire contents of which are incorporated into this application by reference.

[0002] This application relates to the technical field of negative electrode materials, and more particularly to negative electrode materials, methods for manufacturing the same, and lithium-ion batteries. [Background technology]

[0003] Silicon-based anode materials have advantages such as high specific capacity, low voltage platform, environmental friendliness, and abundant resources, and are expected to be applied to next-generation high-specific-energy lithium-ion batteries as an alternative to graphite anodes. However, silicon undergoes a huge volume change during the deburring and embedding process, which easily leads to particle pulverization and makes it prone to detaching from the current collector. Furthermore, the repeated volume changes during the electrochemical cycle of silicon materials cause the SEI film formed on the surface of the silicon material to constantly break down and regenerate, leading to continuous consumption of lithium ions and ultimately rapid capacity decay.

[0004] Crystalline silicon in silicon-based anode materials is a factor that causes changes in the volume expansion of the silicon-based anode material. To solve these problems, scientists can usually suppress the volume expansion of crystalline silicon to some extent by improving processes such as nanotechnology, carbon coating, and polymer coating of crystalline silicon. However, the above methods have limitations in their ability to suppress the volume expansion of silicon and cannot meet the demand for existing high-energy-density lithium-ion batteries.

[0005] Therefore, there is a need for anode materials that possess low expansion properties and excellent cycle performance. [Overview of the Initiative]

[0006] The embodiments of this application provide an anode material that can improve the expansion performance and cycle performance of the anode material, a method for manufacturing the same, and a lithium-ion battery.

[0007] In the first embodiment, the anode material according to the embodiment of the present application includes an active material. The active material includes a porous matrix and a silicon matrix. At least a portion of the silicon matrix is ​​distributed within the pores of the porous matrix. The infrared spectrum obtained by measuring the anode material using an infrared spectrometer has a wavenumber of 2090 cm⁻¹. -1 The stretching vibration peak and wavenumber of the SiH2 bond are 2000 cm. -1 The stretching vibration peaks of the SiH bond and the SiH bond exist. The ratio Z of the vibration peak area of ​​the SiH2 bond to the vibration peak area of ​​the SiH bond in the negative electrode material is 0.01 to 5.0.

[0008] The technical solution of this application has at least the following beneficial effects.

[0009] The active material of the negative electrode material of the present application includes a porous matrix and a silicon matrix, and the silicon matrix is distributed in the pores of the porous matrix. The porous matrix relaxes the volume expansion of the silicon matrix and acts as an elastic conductor of the negative electrode material, providing an ion and electron transport path to the negative electrode material during the charge and discharge process, enhancing the conductivity of the negative electrode material, and improving the rate performance of the negative electrode material. Since the silicon matrix is embedded in the pores of the porous matrix, the aggregation of the silicon matrix particles is reduced, and further the problem of the destruction of the entire structure of the negative electrode material due to stress concentration is reduced. Next, the silicon matrix has a high lithium intercalation voltage (~0.4V) and can suppress the formation of lithium dendrites (the lithium dendrite formation potential is ~0 V), and further improve the safety of the application of the negative electrode material to the battery. In addition, the ratio Z of the vibration peak area of the SiH2 bond to the vibration peak area of the SiH in the negative electrode material of the present application is 0.01 to 5.0, and the stability of the SiH bond is greater than that of the SiH2 bond. A silicon matrix having many SiH bonds is advantageous for improving the structural stability of the negative electrode material, reducing the occurrence of side reactions between the negative electrode material and the electrolyte, and further improving the cycle performance and expansion performance of the negative electrode material.

Brief Description of the Drawings

[0010] [Figure 1] It is a manufacturing flowchart of the negative electrode material according to the present application. [Figure 2] It is an infrared spectrum diagram of the negative electrode material manufactured in Example 2 of the present application. [Figure 3] It is a Raman spectrum diagram of the negative electrode material manufactured in Example 2 of the present application.

Modes for Carrying Out the Invention

[0011] To better understand the technical aspects of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0012] As is clear, the embodiments described are only a selection of, not all, embodiments of the present application. All other embodiments obtained by a person skilled in the art without any creative work based on the embodiments in the present application are all within the scope of the protection of the present application.

[0013] Furthermore, the terms “first” and “second” are used solely to describe the purpose and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features shown. Therefore, features designated as “first” or “second” may explicitly or implicitly include one or more features.

[0014] For ease of understanding of this application, certain terms are appropriately defined herein. Unless otherwise defined herein, scientific and technical terms used herein have the meanings generally understood by those skilled in the art to which this application pertains.

[0015] The negative electrode material according to the embodiment of this application includes an active material. The active material includes a porous matrix and a silicon matrix. At least a portion of the silicon matrix is ​​distributed within the pores of the porous matrix. The infrared spectrum obtained by measuring the negative electrode material using an infrared spectrometer has a wavenumber of 2090 cm⁻¹. -1 The stretching vibration peak and wavenumber of the SiH2 bond are 2000 cm. -1 The stretching vibration peaks of the SiH bond and the SiH bond exist. The ratio Z of the vibration peak area of ​​the SiH2 bond to the vibration peak area of ​​the SiH bond in the negative electrode material is 0.01 to 5.0.

[0016] In the above embodiment, the active material of the negative electrode material of the present invention includes a porous matrix and a silicon matrix, the silicon matrix being distributed in the pores of the porous matrix. The porous matrix mitigates the volume expansion of the silicon matrix and acts as an elastic conductor of the negative electrode material, providing ion and electron transmission paths to the negative electrode material during the charge and discharge process, thereby enhancing the conductivity of the negative electrode material and improving the magnification performance of the negative electrode material. Since the silicon matrix is ​​embedded in the pores of the porous matrix, it is also possible to reduce the problem of aggregation of silicon matrix particles and, consequently, the destruction of the entire negative electrode material structure due to stress concentration. Furthermore, the silicon matrix has a high lithium embedding voltage (~0.4V), which can suppress the formation of lithium dendrites (the lithium dendrite formation potential is ~0V), and can further improve the safety of the negative electrode material's application to batteries. In addition, the ratio Z of the vibrational peak area of ​​the SiH2 bond to the vibrational peak area of ​​SiH in the negative electrode material of the present invention is 0.01 to 5.0, indicating that the stability of the SiH bond is greater than that of the SiH2 bond. A silicon matrix with a high number of SiH bonds is advantageous for improving the structural stability of the anode material, reducing the occurrence of side reactions between the anode material and the electrolyte, and further improving the cycle performance and expansion performance of the anode material. SiH, SiH2, and SiH3 bonds are generated during the silane decomposition process. SiH3 bonds are present in large quantities only when silane decomposition is insufficient.

[0017] Compared to anode materials containing crystalline silicon, crystalline silicon undergoes a two-phase reaction during lithium storage, with the crystalline silicon converting to an amorphous Li-Si phase. In this invention, the random structure of the silicon matrix results in a uniform reaction during lithium storage. Therefore, the volume expansion of the silicon matrix in this invention is lower than that of crystalline silicon. The small volume expansion of the silicon matrix in this invention improves the expansion performance of the anode material.

[0018] In this application, the value of Z may be 0.01, 0.05, 0.1, 0.3, 0.8, 1.0, 2.0, 3.0, 4.0, or 5.0, but of course, it may be any other value within the above range, and this application does not limit it. Within the above limited range, a smaller Z value indicates that there are more SiH bonds in the silicon matrix, which stabilizes the silicon matrix and is advantageous for improving the cycle performance and expansion performance of the anode material. A Z value greater than 5 indicates that there are too many SiH2 bonds in the silicon matrix of the anode material, which may lead to the appearance of SiH3 bonds, making the structure of the anode material unstable and potentially reducing the cycle performance and expansion performance of the anode material. In some embodiments, the value of Z is 0.05 to 3.0. Preferably, the value of Z is 0.05 to 0.5.

[0019] In some embodiments, the silicon matrix includes silicon particles.

[0020] In some embodiments, the porosity of the negative electrode material is 0.01% to 10%, for example, 0.01%, 1%, 3%, 5%, 8%, or 10%, and of course, it may be other values ​​within the above range, and this application is not limited thereto. Within the above limited range, it is possible to suppress volume expansion while improving the energy density of the negative electrode material.

[0021] In this invention, the negative electrode material was immersed in concentrated nitric acid at a concentration of 1 M for 4 hours, and then a 20% by mass fraction HF acid solution was added drop by drop to the negative electrode material, causing yellow smoke to be generated. The addition of the solution was repeated until no more yellow smoke was generated in the solution. Finally, the residue was removed with concentrated nitric acid at a concentration of 1 M, and then the material was washed and dried to obtain a negative electrode material from which the silicon matrix had been removed, i.e., a porous matrix.

[0022] In some embodiments, the anode material has a porosity of 30% to 70% after the silicon matrix is ​​removed, such as 30%, 40%, 50%, 55%, 60%, or 70%, and of course, it may be other values ​​within the above range, and the present application is not limited thereto. Within the above limited range, the anode material after the silicon matrix is ​​removed has sufficient space for dispersing the silicon matrix and has sufficient resistance to crushing, and can suppress volume expansion of the anode material while improving the energy density of the anode material.

[0023] In some embodiments, the average pore size after the silicon matrix has been removed from the negative electrode material is 0.2 nm to 10 nm, and may be, for example, 0.2 nm, 0.5 nm, 2 nm, 5 nm, 8 nm, or 10 nm, but of course, it may be any other value within the above range, and this application is not limited thereto.

[0024] In some embodiments, the average particle size of the silicon matrix is ​​1 nm to 10 nm, for example, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, or 10 nm, but of course, other values ​​within the above range are also possible, and this application is not limited thereto. Within the above particle size range, it is advantageous for embedding the silicon matrix into the pores of the porous matrix. In some embodiments, the average particle size of the silicon matrix is ​​1 nm to 5 nm.

[0025] In some embodiments, the mass ratio of silicon matrix in the anode material is 5% to 90%, and may be, for example, 5%, 10%, 20%, 50%, 70%, 80%, or 90%, but of course, it may be other values ​​within the above range, and this application does not limit it. Within the above limit range, the anode material of this application indicates that it supports a larger amount of silicon matrix, which is advantageous for improving the capacity performance of the anode material.

[0026] In some embodiments, at least a portion of the silicon matrix is ​​distributed on the surface of the porous matrix. To improve the magnification performance of the anode material, it is understood that the silicon matrix of the present invention is primarily distributed within the porous matrix.

[0027] In some embodiments, the anode material further includes a coating layer provided on at least a portion of the surface of the active material. On the one hand, the presence of the coating layer reduces the risk of the electrolyte entering the interior of the anode material and causing side reactions that lead to a decrease in initial efficiency and capacity. On the other hand, the coating layer can mitigate the volume expansion of silicon to some extent, reducing the overall volume expansion of the anode material and decreasing the swelling of the electrode sheet made of the anode material.

[0028] In some embodiments, the coating layer comprises at least one of a carbon material, a metal oxide, and a metal sulfide.

[0029] In some embodiments, the coating layer may be at least one of a carbon layer, a metal oxide layer, and a metal sulfide layer.

[0030] In some embodiments, the carbon material comprises at least one of graphene, soft carbon, hard carbon, and a conductive polymer. Specifically, the conductive polymer comprises at least one of polyaniline, polyacetylene, polypyrrole, polythiophene, poly-3-hexylthiophene, poly-p-phenyleneethylene, polypyridine, and polyphenylenevinylene.

[0031] In some embodiments, the metal oxide includes at least one of titanium oxide, aluminum oxide, lithium oxide, cobalt oxide, and vanadium oxide.

[0032] In some embodiments, the metal sulfide includes at least one of tin sulfide, molybdenum sulfide, titanium sulfide, iron sulfide, and copper sulfide.

[0033] In some embodiments, the thickness of the coating layer is 5 nm to 500 nm, for example, 5 nm, 10 nm, 30 nm, 80 nm, 120 nm, 200 nm, 300 nm, 400 nm, or 500 nm, but of course, other values ​​within the above range are also possible and are not limited here. In some embodiments, the thickness of the coating layer is 10 nm to 100 nm. The coating layer can reduce contact between silicon and electrolyte, reduce the formation of passivation films, and improve the reversible electrical capacity of the battery. If the thickness of the coating layer is greater than 500 nm, the lithium-ion transmission efficiency decreases, which is unfavorable for high-magnification charge and discharge of the anode material, and the overall performance of the anode material decreases. Also, if the thickness of the coating layer is less than 5 nm, it is unfavorable for improving the conductivity of the anode material, the ability to suppress volume expansion of the anode material is weak, and this leads to poor cycle performance.

[0034] In some embodiments, the median particle size D50 of the negative electrode material is 5 μm to 10 μm, and may be, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, and of course may be other values ​​within the above range, and is not limited thereto. In some embodiments, the median particle size D50 of the negative electrode material is 5 μm to 8 μm, and preferably the median particle size D50 of the negative electrode material is 7 μm to 8 μm.

[0035] In some embodiments, the minimum particle size D00 of the negative electrode material is 1 μm to 3 μm, and may be, for example, 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm, and of course may be other values ​​within the above range, and the present application is not limited thereto. In some embodiments, the minimum particle size D00 of the negative electrode material is 1 μm to 2 μm.

[0036] In some embodiments, the D90 of the negative electrode material is 14 μm to 25 μm, and may be, for example, 14 μm, 17 μm, 20 μm, 23 μm, or 25 μm, and of course may be other values ​​within the above range, and the present application is not limited thereto. In some embodiments, the D90 of the negative electrode material is 18 μm to 20 μm.

[0037] When testing the anode material using a laser particle size analyzer, a symmetric distribution similar to a normal distribution exists. In the above symmetric distribution, D90 is the particle size at which the cumulative number distribution of the material particles is 90%, D00 is the minimum size of the material particles, and it means the minimum diameter that can be measured in the above distribution. D50 is the particle size at which the cumulative number distribution of the material particles is 50%, and it is also called the median particle size. An ideal battery material needs to have a relatively narrow particle size distribution. According to research, material particles that are too small will make it difficult to deposit silicon, resulting in the deterioration of the capacity retention rate due to the continuous consumption of the electrolyte by the battery material during cycling. On the other hand, material particles that are too large will deposit too much silicon matrix. The excessive silicon matrix will give the anode material a larger expansion rate, easily cause particle pulverization during cycling, and easily cause continuous thickening of the SEI. Therefore, by controlling the particle size distribution, the cycle performance of the anode material can be improved. In the anode material of the present application, since the size distribution of the material particles is relatively concentrated, the material can reduce the above problems, and at the same time, it has a higher deposition density, which can improve the electrochemical performance and cycle performance of the anode material.

[0038] In some embodiments, the porous matrix includes porous carbon. In some embodiments, in the Raman spectrum diagram obtained by Raman spectroscopy using a measurement light source with a wavelength of 633 nm for the anode material, the anode material has a characteristic peak I at the position of 1310 cm -1 ~1350 cm -1 and a characteristic peak I at the position of 1580 cm D ~1620 cm -1 It is shown to have. I -1 / I G is 1.6 - 2.5, for example, it may be 1.6, 1.8, 2.0, 2.2, 2.3 or 2.5, etc. Of course, it may also be other values within the above range, and this is not limited in the present application. In the Raman spectrum diagram of the present application, the D peak corresponds to the pores and defects of the porous carbon, and the G peak corresponds to the deposition mode of the graphite sheet layer E2g of the porous carbon. The present application is about I​​​​D / I G This demonstrates the ease of silicon deposition on porous carbon. Within the above limited range, it was shown that porous carbon has a relatively large number of pores and defects. The surface and interior of porous carbon have many silicon nucleation sites, which is favorable for silicon deposition and can significantly increase the silicon load in the anode material, thereby increasing the efficient utilization rate of the silicon source, subsequently increasing the tap density and specific capacity of the entire anode material, and increasing the energy density of the entire battery material made from the anode material. In some embodiments, I D / I G It is 1.6 to 2.3. Preferably, I D / I G The range is 1.8 to 2.2.

[0039] In some embodiments, the specific surface area of ​​the negative electrode material is 1.0 m². 2 / g~10.0m 2 It is expressed as / g, for example, 1.0m 2 / g, 2.0m 2 / g, 3.0m 2 / g, 4.0m 2 / g, 5.0m 2 / g, 6.0m 2 / g, 7.0m 2 / g, 8.0m 2 / g, 9.0m 2 / g or 10.0m 2 The value may be / g, or of course, any other value within the above range; this application is not limited thereto. By controlling the specific surface area of ​​the negative electrode material within the above range, the formation of the negative electrode material SEI film can be reduced, and the electrochemical performance of the negative electrode material can be improved.

[0040] In some embodiments, the powder conductivity of the negative electrode material is 0.1 S / cm to 10.0 S / cm, and may be, for example, 0.1 S / cm, 1.0 S / cm, 3.0 S / cm, 5.0 S / cm, 7.0 S / cm, 9.0 S / cm, or 10.0 S / cm, and of course, other values ​​within the above range are also possible. The present invention is not limited thereto. As can be understood, by controlling the powder conductivity of the negative electrode material within the above range, the magnification performance of the negative electrode material can be improved.

[0041] Embodiments of the present invention also provide a method for manufacturing a negative electrode material. As shown in Figure 1, the method for manufacturing the negative electrode material includes the following steps.

[0042] In S100, carbon-based raw materials and activators are placed in a VC mixer with a processing capacity of 10L-50L in a fixed ratio, stirred at a frequency of 5-30HZ for 30-90 min, and after uniform mixing, the mixture is transferred to a rotary furnace for a first heat treatment. During the heat treatment, the oxygen content of the rotary furnace is kept below 100 ppm, and the pressure of the rotary furnace is set to 10-100 Pa. After the heat treatment, the sample is mechanically pulverized to obtain a first precursor with a particle size D50 of 5-15 μm.

[0043] In S200, the first precursor is placed in an inert gas atmosphere, and the first precursor is subjected to a second heat treatment. The deviation between the reaction system temperature and the set value must be less than 10°C, a constant temperature must be maintained for 10-60 mins after the reactor reaches the reaction temperature, the total reaction gas rate must be 15-50 L / min, the silane concentration 10%-60%, the reaction system pressure 0-30 kPa, and the active material must be obtained after the reaction is complete. The negative electrode material contains the aforementioned active material. The temperature of the second heat treatment is 420°C-800°C.

[0044] In the above technical proposal, the present invention performs a first heat treatment on a mixture of carbon-based raw materials and an activator to form pores on the surface and inside the carbon-based raw materials, thereby obtaining porous carbon, i.e., a first precursor. Furthermore, a second heat treatment is performed by passing silane gas through the porous carbon. By controlling the temperature of the second heat treatment to 420°C to 800°C, the silane is sufficiently decomposed so that a large amount of silicon matrix existing as SiH bonds is generated. At this time, the silicon matrix is ​​deposited inside and / or on the surface of the first precursor. This results in obtaining a core in which at least some of the silicon matrix is ​​distributed within the pores of the porous carbon. Here, the silicon matrix existing in the form of many SiH bonds can improve the structural stability of the anode material, improve the mechanical performance of the anode material, reduce the occurrence of side reactions between the anode material and the electrolyte, mitigate volume expansion during the lithium embedding stage of the anode material, and improve the circulation stability of the anode material. The porous carbon is coated on the surface of at least some of the silicon matrix. On the one hand, porous carbon can act as an elastic conductor, providing a transmission path for ions and electrons during the charge-discharge process of the negative electrode material, thereby increasing the conductivity between the silicon matrix and the surrounding environment and enhancing the anode material's charging performance. On the other hand, embedding the silicon matrix in porous carbon can increase the conductivity of the silicon matrix, further enhancing the material's charging performance and meeting the requirements for the battery to achieve rapid charging characteristics.

[0045] When silane is sufficiently decomposed, it generates a large amount of silicon matrix containing SiH bonds. That is, the silicon matrix contains many SiH bonds as chemical bonds. In silicon matrix generated without sufficient silane decomposition, the silicon matrix exists in the form of SiH bonds, SiH2 bonds, and SiH3 bonds. The silicon matrix produced by the manufacturing method of the present invention can sufficiently decompose silane into amorphous silicon without generating polycrystalline silicon. At the same time, because the silicon matrix contains many SiH bonds, the ratio Z of the vibration peak area of ​​SiH2 bonds to the vibration peak area of ​​SiH bonds in the anode material satisfies Z = 0.01 to 5.0, and the cycle performance and expansion performance of the anode material are improved.

[0046] The manufacturing method of the present invention will be specifically described below based on examples. The manufacturing method of the negative electrode material according to the present invention includes the following steps.

[0047] In S100, carbon-based raw materials and activators were placed in a VC mixer with a processing capacity of 10-50 L in a fixed ratio, stirred at a frequency of 5-30 HZ for 30-90 min, and after uniform mixing, the mixture was transferred to a rotary furnace for a first heat treatment. During the heat treatment, the oxygen content of the rotary furnace was kept below 100 ppm, and the pressure of the rotary furnace was set to 10-100 Pa. After the heat treatment, the sample was mechanically pulverized to obtain a first precursor with a particle size D50 of 5-15 μm.

[0048] In some embodiments, the carbon-based raw material includes at least one of fruit husk char, straw char, resin char, asphalt char, and sugars.

[0049] In some embodiments, the activator comprises at least one of water vapor, an alkaline substance, and a mold agent. The activator is activated by contact with a carbon-based material at a certain temperature. The activator can erode the surface of the carbon-based material at high temperatures. This reopens and further enlarges pores that were blocked in the carbon-based material, and new pores are generated in some structures by selective oxidation.

[0050] In some embodiments, the basic substance includes at least one of potassium hydroxide and sodium hydroxide.

[0051] In some embodiments, the mold agent comprises at least one of calcium hydroxide, calcium oxide, magnesium oxide, magnesium hydroxide, melamine, aluminum oxide, and polymer mold agents. Specific examples of polymer mold agents include polyurethane, melamine resin, cellulose, polystyrene, and polymethyl methacrylate.

[0052] In some embodiments, the temperature of the first heat treatment is 600°C to 2000°C, and may be, for example, 600°C, 800°C, 1000°C, 1100°C, 1500°C, 1800°C, or 2000°C, and of course may be other values ​​within the above range, and is not limited thereto. It is understood that controlling the temperature of the first heat treatment within the above range is advantageous in that the carbon-based raw material is activated into pores, thereby increasing the porosity of porous carbon. In some embodiments, the temperature of the first heat treatment is 800°C to 1500°C. Preferably, the temperature of the first heat treatment is 800°C to 1100°C.

[0053] In some embodiments, the heating rate of the first heat treatment is 5°C / min to 20°C / min, and may be, for example, 5°C / min, 10°C / min, 15°C / min, 18°C / min, or 20°C / min. Of course, it may be any other value within the above range, and is not limited thereto.

[0054] In some embodiments, the duration of the first heat treatment is 2 to 10 hours, and may be, for example, 2 hours, 3 hours, 5 hours, 8 hours, or 10 hours. Of course, it may be any other value within the above range, and is not limited thereto.

[0055] In some embodiments, the process further includes washing and drying the material obtained from the first heat treatment after the first heat treatment.

[0056] In some embodiments, the washing process involves first pickling the first heat-treated material with acid and then rinsing it with water. Here, the acid used for pickling is at least one of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, phosphoric acid, perchloric acid, acetic acid, and benzoic acid. The concentration of the acid is 1 mol / L to 5 mol / L, and may be, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L, but may be other values ​​within the above range and is not limited thereto. The purpose of pickling is to remove excess activators from the material. After pickling, the first precursor is washed with deionized water to wash the product to a neutral pH.

[0057] In some embodiments, the drying temperature is 80°C to 150°C. Specific temperatures may be 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, and 150°C, but are not limited to these values ​​and may be other values ​​within the above range.

[0058] In some embodiments, the drying time is 24 to 72 hours. The specific time may be 24, 30, 36, 42, 48, 52, 60, 72 hours, etc., but of course, it may be any other value within the above range and is not limited thereto.

[0059] In some embodiments, the drying equipment is one of an oven, an oven furnace, or a double cone dryer.

[0060] In some embodiments, the step of grinding and sieving the material obtained in the first heat treatment is further included after the first heat treatment.

[0061] In some embodiments, grinding is performed using at least one of ball mill grinding, air jet grinding, and mechanical grinding. In some embodiments, mechanical grinding is used.

[0062] In some embodiments, the median particle size of the first precursor after grinding and sieving is 5 μm to 10 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, but of course, it may be any other value within the above range and is not limited thereto.

[0063] In S200, a second heat treatment is performed on the first precursor in a silane gas atmosphere to obtain the anode material. The temperature of the second heat treatment is 420°C to 800°C.

[0064] In some embodiments, the inflow rate of silane gas is 1 L / min to 10 L / min, and may be, for example, 1 L / min, 3 L / min, 5 L / min, 7 L / min, 9 L / min, or 10 L / min, but may of course be other values ​​within the above range and is not limited thereto. Within the above limited range, it is advantageous for the silane to decompose sufficiently and generate a large amount of silicon matrix existing in the form of SiH bonds.

[0065] In some embodiments, the temperature of the second heat treatment is 420°C to 800°C, and may be, for example, 420°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, or 800°C, and of course may be other values ​​within the above range, and is not limited thereto. In some embodiments, the temperature of the second heat treatment is 550°C to 650°C. Within the above limited range, it is advantageous for silicon matrices in which a large amount of silicon matrix exists in the form of SiH composites due to sufficient decomposition of silane gas, and is advantageous for improving the structural stability of the anode material, and consequently the cycle performance and expansion performance of the anode material. If the temperature is higher than 800°C, amorphous silicon generated by the decomposition of silane gas is more easily converted to crystalline silicon, leading to poor expansion performance of the anode material. If the second heat treatment temperature is lower than 420°C, the silane gas decomposition is insufficient, the conversion rate of silane decomposition is low, and the silicon matrix produced by silane decomposition mainly exists as a coexistence of SiH, SiH2, and SiH3 bonds, reducing the structural stability of the negative electrode material.

[0066] In some embodiments, the heating rate in the second heat treatment is 3°C / min to 20°C / min, and specifically may be 3°C / min, 5°C / min, 8°C / min, 10°C / min, 13°C / min, 16°C / min, 18°C / min, or 20°C / min, and of course may be other values ​​within the above range, and is not limited thereto.

[0067] In some embodiments, the second heat treatment is carried out in a protective gas atmosphere containing at least one of nitrogen gas, argon gas, and helium gas.

[0068] In some embodiments, the duration of the second heat treatment is 100 min to 600 min, and may be, for example, 100 min, 200 min, 300 min, 400 min, 500 min, or 600 min, but may, of course, be any other value within the above range, and is not limited thereto.

[0069] In some embodiments, the second heat treatment apparatus includes at least one of a kiln, a chemical vapor deposition apparatus, and a chemical vapor deposition apparatus.

[0070] In some embodiments, a third heat treatment is further performed after the second heat treatment by mixing the coating material with the material obtained in the second heat treatment.

[0071] In this step, the coating layer formed by mixing the coating material with the material obtained in the second heat treatment and then performing a third heat treatment can reduce the decrease in initial efficiency and capacity caused by the electrolyte entering the interior of the negative electrode material and causing side reactions. At the same time, it can work in cooperation with the core material to mitigate the volume expansion of the silicon matrix, reduce the overall volume expansion of the negative electrode material, and decrease the swelling of the electrode sheet made of the negative electrode material.

[0072] In some embodiments, the coating material comprises at least one of a carbon source, a metal oxide, and a metal sulfide.

[0073] In some embodiments, the carbon source includes at least one of a gaseous carbon source and a solid carbon source.

[0074] In some embodiments, the gaseous carbon source includes at least one of acetylene, methane, propylene, benzene, ethanol, methanol, ethylene, propane, and butane.

[0075] In some embodiments, the inflow rate of the gaseous carbon source is 1 L / min to 15 L / min, and may be, for example, 1 L / min, 3 L / min, 5 L / min, 8 L / min, 10 L / min, 12 L / min, or 15 L / min. Of course, it may be any other value within the above range, and is not limited thereto.

[0076] In some embodiments, the solid carbon source includes at least one of sucrose, fructose, glucose, pitch, phenolic resin, polyimide, citric acid, epoxy resin, amino resin, polystyrene, polyacrylic acid, carboxymethylcellulose, and butyrate acetate fiber.

[0077] In some embodiments, the mass ratio of the solid carbon source to the material obtained by the second heat treatment is (0.2~2):1, and may be, for example, 0.2:1, 0.5:1, 0.8:1, 1.5:1, 1.8:1, or 2:1, but may of course be other values ​​within the above range and are not limited thereto.

[0078] In some embodiments, the metal oxide includes at least one of iron oxide, zinc oxide, tin oxide, copper oxide, and titanium oxide.

[0079] In some embodiments, the metal sulfide includes at least one of tin sulfide, molybdenum sulfide, titanium sulfide, iron sulfide, and copper sulfide.

[0080] In some embodiments, the mass ratio of the metal oxide to the material obtained by the second heat treatment is (0.2~2):1, and may be, for example, 0.2:1, 0.5:1, 0.8:1, 1.5:1, 1.8:1, or 2:1, but may of course be other values ​​within the above range and are not limited thereto.

[0081] In some embodiments, the mass ratio of the metal sulfide to the material obtained by the second heat treatment is (0.2~2):1, and may be, for example, 0.2:1, 0.5:1, 0.8:1, 1.5:1, 1.8:1, or 2:1, but of course, it may be any other value within the above range and is not limited thereto.

[0082] In some embodiments, the temperature of the third heat treatment is 300°C to 1100°C, and may be, for example, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, and 1100°C, but may of course be other values ​​within the above range and is not limited thereto. Within the above limited range, it can be guaranteed that the carbonization of the coating material is complete and that it does not significantly affect the silicon matrix of the core. To reduce the change in the silicon matrix during the third heat treatment process, it is preferable that the temperature of the third heat treatment is 400°C to 800°C. More preferably, the temperature of the third heat treatment is 500°C to 700°C.

[0083] In some embodiments, the duration of the third heat treatment is 2 to 5 hours, and may be, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours, but may, of course, be any other value within the above range and is not limited thereto.

[0084] In a third embodiment, the present application provides a lithium-ion battery comprising a negative electrode material manufactured by the manufacturing method described above.

[0085] The embodiments of this application will be described below, but the application is not limited to these examples unless it deviates from its purpose.

[0086] [Example 1] (1) 400 g of coal pitch, 120 g of calcium hydroxide, and 50 g of potassium hydroxide were mixed in a VC mixer at a frequency of 20 Hz for 30 minutes with the aim of preparing a precursor with a uniform pore size distribution. After uniform mixing, the mixture was left in a rotary furnace. The oxygen content of the rotary furnace was set to less than 100 ppm, the pressure of the rotary furnace was set to 10-100 Pa, and the temperature was raised to 700 °C at 10 °C / min. The mixture was kept at a constant temperature for 5 hours, the obtained material was immersed in 2 mol / L hydrochloric acid for 1 hour, filtered, washed to neutral with pure water, and baked in a 100 °C oven for 4 hours. After that, it was crushed and sieved through a 325 mesh sieve.

[0087] (2) To ensure the temperature stability of the CVD reactor, 200 g of the material obtained in step (1) was placed in the CVD reactor, the temperature was raised to 550°C at 5°C / min, and the reactor was kept at a constant temperature for 60 min. Then, 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas were flowed through the reactor, the reaction system pressure was set to 0-30 kPa, and the reaction was carried out for 300 min to obtain the first precursor.

[0088] (3) The first precursor was placed in a CVD reactor, heated to 700°C at 10°C / min, and reacted for 150 minutes with 1 L / min of C3H6 and 2 L / min of nitrogen flowing through it.

[0089] (4) The material obtained in step (3) was placed in a VC mixer, crushed, and passed through a 325-mesh chute to obtain the negative electrode material.

[0090] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. The silicon matrix often exists in the form of SiH bonds. The coating layer is a carbon layer.

[0091] [Example 2] (1) 400 g of coal pitch, 120 g of calcium hydroxide, and 50 g of potassium hydroxide were mixed in a VC mixer at a frequency of 20 Hz for 30 minutes with the aim of preparing a precursor with a uniform pore size distribution. After uniform mixing, the mixture was left in a rotary furnace. The oxygen content of the rotary furnace was reduced to less than 100 ppm, the pressure of the rotary furnace was set to 10-100 Pa, and the temperature was raised to 900 °C at 10 °C / min. The mixture was kept at a constant temperature for 5 hours, the resulting material was immersed in 2 mol / L hydrochloric acid for 1 hour, filtered, washed to neutral with pure water, and baked in a 100 °C oven for 4 hours. After that, it was crushed and sieved through a 325 mesh sieve.

[0092] (2) To ensure the temperature stability of the CVD reactor, 200 g of the material obtained in step (1) was placed in the CVD reactor, the temperature was raised to 550°C at 5°C / min, and the reactor was kept at a constant temperature for 60 min. Then, 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas were flowed through the reactor, the reaction system pressure was set to 0-30 kPa, and the reaction was carried out for 300 min to obtain the first precursor.

[0093] (3) The first precursor was placed in a CVD reactor, heated to 700°C at 10°C / min, and reacted for 150 minutes with 1 L / min of C3H6 and 2 L / min of nitrogen flowing through it.

[0094] (4) The material obtained in step (3) was placed in a VC mixer, crushed, and passed through a 325-mesh chute to obtain the negative electrode material.

[0095] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0096] The infrared spectral diagram of the negative electrode material manufactured in this embodiment is shown in Figure 2. As can be seen from Figure 2, the negative electrode material manufactured in Example 2 has a wavenumber of 2090 cm⁻¹. -1 The stretching vibration peak and wavenumber of the SiH2 bond are 2000 cm. -1A stretching vibration peak exists in the SiH bond. The infrared spectral data was imported into Origin software, and the wavenumber was set to 2000 cm. -1 The stretching vibration peak and wavenumber of the SiH bond are 2090 cm⁻¹. -1 The stretching vibration peak of the SiH2 bond is used as the bimodal fitting position, and the Gauss fitting optimization method is employed to fit the two resulting peaks. The fitting dispersion R2 is within the range of 0.6 to 0.95. The ratio of peak areas Z represents the ratio of SiH bonds to SiH2 bonds, as well as the degree of silane decomposition reaction. Also, in Figure 2, 907 cm⁻¹ is shown. -1 No vibrational peaks of SiH3 bonds were observed, indicating that SiH3 bonds do not exist in the silicon matrix carbon material, and further demonstrating sufficient silane decomposition.

[0097] The Raman spectrum of the negative electrode material manufactured in this embodiment is shown in Figure 3. As can be seen from Figure 3, the negative electrode material of Example 2 has a spectrum of 480 cm⁻¹. -1 A characteristic peak is present, which is identified as the characteristic peak for amorphous silicon, and this explains that amorphous silicon is sufficiently generated by silane decomposition in this example.

[0098] [Example 3] (1) 400g of coal pitch, 120g of calcium hydroxide, and 50g of potassium hydroxide were mixed in a VC mixer at a frequency of 20Hz for 30 minutes with the aim of preparing a precursor with a uniform pore size distribution. After uniform mixing, the mixture was left in a rotary furnace. The oxygen content of the rotary furnace was set to less than 100ppm, the pressure of the rotary furnace was set to 10-100pa, and the temperature was raised to 1100°C at a rate of 10°C / min. The mixture was kept at a constant temperature for 5 hours, the resulting material was immersed in 2mol / L hydrochloric acid for 1 hour, filtered, washed to neutral with pure water, and baked in a 100°C oven for 4 hours. After that, it was crushed and sieved through a 325-mesh sieve.

[0099] (2) To ensure the temperature stability of the CVD reactor, 200 g of the material obtained in step (1) was placed in the CVD reactor, the temperature was raised to 550°C at 5°C / min, and the reactor was kept at a constant temperature for 60 min. Then, 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas were flowed through the reactor, the reaction system pressure was set to 0-30 kPa, and the reaction was carried out for 300 min to obtain the first precursor.

[0100] (3) The first precursor was placed in a CVD reactor, heated to 700°C at 10°C / min, and reacted for 150 minutes with 1 L / min of C3H6 and 2 L / min of nitrogen flowing through it.

[0101] (4) The material obtained in step (3) was placed in a VC mixer, crushed, and passed through a 325-mesh chute to obtain the negative electrode material.

[0102] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0103] [Example 4] The difference between Example 4 and Example 2 lies in step (2). Specifically, the difference is that the temperature is raised to 420°C at a rate of 5°C / min, and the reaction is carried out for 300 minutes by flowing 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas.

[0104] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0105] [Example 5] The difference between Example 5 and Example 2 lies in step (2). Specifically, in Example 5, the temperature is raised to 450°C at a rate of 5°C / min, and the reaction is carried out for 300 minutes by flowing 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas.

[0106] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0107] [Example 6] The difference between Example 6 and Example 2 lies in step (2). Specifically, the difference is that the temperature is raised to 480°C at 5°C / min, and the reaction is carried out for 300 minutes by flowing 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas.

[0108] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0109] [Example 7] The difference between Example 7 and Example 2 lies in step (2). Specifically, the difference is that the temperature is raised to 510°C at a rate of 5°C / min, and the reaction is carried out for 300 minutes by flowing 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas.

[0110] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0111] [Example 8] The difference between Example 8 and Example 2 lies in step (2). Specifically, the difference is that the temperature is raised to 600°C at a rate of 5°C / min, and the reaction is carried out for 300 minutes by flowing 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas.

[0112] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0113] [Example 9] The difference between Example 9 and Example 2 lies in step (2). Specifically, the difference is that the temperature is raised to 650°C at a rate of 5°C / min, and the reaction is carried out for 300 minutes by flowing 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas.

[0114] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0115] [Example 10] The difference between Example 10 and Example 2 lies in step (2). Specifically, the difference is that the temperature is raised to 800°C at a rate of 5°C / min, and the reaction is carried out for 300 minutes by flowing 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas.

[0116] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0117] [Example 11] The difference between Example 11 and Example 4 lies in step (2). Specifically, the difference is that the temperature is raised to 420°C at a rate of 5°C / min, and the reaction is carried out for 350 minutes by flowing 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas.

[0118] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0119] [Example 12] The difference between Example 12 and Example 8 lies in step (2). Specifically, the difference is that the temperature is raised to 650°C at a rate of 5°C / min, and the reaction is carried out for 270 minutes by flowing 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas.

[0120] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0121] [Example 13] (1) Place 500g of coconut shell charcoal in a reactor, raise the temperature to 900°C at 10°C / min, and activate it for 120 minutes by passing 30g / min of steam through it. Then, immerse the resulting mixture in 2mol / L hydrochloric acid for 1 hour, filter it, wash it to neutral with pure water, bake it in a 100°C oven for 4 hours, then crush it and sift it through a 325-mesh sieve.

[0122] (2) To ensure the temperature stability of the CVD reactor, 200 g of the material obtained in step (1) was placed in the CVD reactor, the temperature was raised to 550°C at 5°C / min, and the reactor was kept at a constant temperature for 60 min. Then, 0.6 L / min of SiH4 and 0.6 L / min of nitrogen gas were flowed through the reactor, the reaction system pressure was set to 0-30 kPa, and the reaction was carried out for 300 min to obtain the first precursor.

[0123] (3) The first precursor was placed in a CVD reactor, heated to 700°C at 10°C / min, and reacted for 150 minutes with 1 L / min of C3H6 and 2 L / min of nitrogen flowing through it.

[0124] (4) The material obtained in step (3) was placed in a VC mixer, crushed, and passed through a 325-mesh chute to obtain the negative electrode material.

[0125] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. Most of the silicon matrix exists as SiH bonds. The coating layer is a carbon layer.

[0126] [Comparative Example 1] In step (1), 400g of coal pitch, 120g of calcium hydroxide, and 50g of potassium hydroxide are mixed in a VC mixer at a frequency of 20Hz for 30 minutes. The purpose of mixing is to prepare a precursor with a uniform pore size distribution. After uniform mixing, the mixture is placed in a rotary furnace, the oxygen content of the rotary furnace is set to less than 100ppm, the pressure of the rotary furnace is set to 10-100Pa, the temperature is raised to 700°C at 10°C / min, and then kept at a constant temperature for 5 hours. The resulting mixture is immersed in 2mol / L hydrochloric acid for 1 hour, filtered, washed to neutral with pure water, baked in a 100°C oven for 4 hours, then crushed and sieved through a 325-mesh sieve.

[0127] In step (2), in order to maintain the temperature stability of the CVD reactor, 200g of the material obtained in step (1) was placed in the CVD reactor, the temperature was raised to 400°C at 5°C / min, the temperature was kept constant for 60min, and 0.6L / min of SiH4 and 0.6L / min of nitrogen gas were flowed to set the pressure of the reaction system to 0-30kPa, and the reaction was carried out for 300min to obtain the first precursor.

[0128] In step (3), the first precursor is placed in a CVD reactor, heated to 700°C at 10°C / min, and reacted for 150 minutes with 1 L / min of C3H6 and 2 L / min of nitrogen gas flowing through it.

[0129] In step (4), the material obtained in step (3) was placed in a VC mixer, crushed, and sieved through a 325-mesh sieve to obtain the anode material.

[0130] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and a silicon matrix located inside and / or on the surface of the porous carbon. The silicon matrix exists in the form of SiH bonds, SiH2 bonds, and SiH3 bonds. The coating layer is a carbon layer.

[0131] [Comparative Example 2] In step (1), 400g of coal pitch, 120g of calcium hydroxide, and 50g of potassium hydroxide are mixed in a VC mixer at a frequency of 20Hz for 30 minutes. The purpose of mixing is to prepare a precursor with a uniform pore size distribution. After uniform mixing, the mixture is placed in a rotary furnace, the oxygen content of the rotary furnace is set to less than 100ppm, the pressure of the rotary furnace is set to 10-100Pa, the temperature is raised to 700°C at 10°C / min, and then kept at a constant temperature for 5 hours. The resulting mixture is immersed in 2mol / L hydrochloric acid for 1 hour, filtered, washed to neutral with pure water, baked in a 100°C oven for 4 hours, then crushed and sieved through a 325-mesh sieve.

[0132] In step (2), in order to maintain the temperature stability of the CVD reactor, 200g of the material obtained in step (1) was placed in the CVD reactor, the temperature was raised to 900°C at 5°C / min, the temperature was kept constant for 60min, and 0.6L / min of SiH4 and 0.6L / min of nitrogen gas were flowed to set the pressure of the reaction system to 0-30kPa, and the reaction was carried out for 300min to obtain the first precursor.

[0133] In step (3), the first precursor is placed in a CVD reactor, heated to 700°C at 10°C / min, and reacted for 150 minutes with 1 L / min of C3H6 and 2 L / min of nitrogen gas flowing through it.

[0134] In step (4), the material obtained in step (3) was placed in a VC mixer, crushed, and sieved through a 325-mesh sieve to obtain the anode material.

[0135] The negative electrode material obtained in this embodiment includes a core and a coating layer covering the surface of the core. The core includes porous carbon and polycrystalline silicon located inside and / or on the surface of the porous carbon. The coating layer is a carbon layer.

[0136] <Performance Test> 1. Regarding the test methods for porosity, pore size, and occupancy, the amount of pores per unit weight of the material (cm²) 3 (g) and body density (g / cm³) 3 It is obtained by calculating the product of (volume / volume). Therefore, porosity is expressed as (volume / volume) based on volume. The (bulk) density can be determined by dividing the mass of the material by the volume of the sample. The amount of pores per unit weight can further be measured under known conditions using nitrogen adsorption methods (micropore and mesopore) or mercury porosimeters (macropore). 2. The D50, D00, and D90 of the negative electrode material are measured using a laser particle size analyzer. The negative electrode material has a symmetrical distribution, such as a normal distribution. In this distribution, D90 is the particle size at which the cumulative distribution of material particles accounts for 90%, D00 is the minimum size of the material particles and represents the smallest diameter that can be measured in the distribution, and D50 is the particle size at which the cumulative distribution of material particles accounts for 50%, and is also called the median particle size. 3. The proportion of silicon matrix mass in the negative electrode material is measured by the specific gravity method. Specifically, silicon dioxide is produced by burning the silicon matrix at high temperature in air, and the mass of the silicon matrix is ​​derived by calculating the mass of the silicon dioxide. Furthermore, the proportion of silicon matrix mass in the negative electrode material is calculated. 4. As test equipment, a Renishaw confocal Raman spectrometer from the UK, model inVia, was used. The test conditions were a 633nm laser, and the test range was 800cm². -1 ~2000cm -1 That was the case. 5. Fourier infrared spectroscopy will be performed using a Thermo Scientific iN10 instrument (model number: US). The spectral range will be 4000 cm². -1 -400cm -1 The infrared test data was imported into the Origin software, and the wavenumber was 1985 cm. -1 Stretching vibration peak of SiH bond and wavenumber 2080 cm⁻¹ -1 The stretching vibration peak of the SiH2 coupling in this region is used as the bimodal fitting position, with wavenumbers 1750–2220 cm⁻¹. -1 The two obtained peaks are fitted to the infrared spectrum using a Gauss fitting optimization method. The ratio Z of the peak areas represents the ratio of SiH bonds to SiH2 bonds. 6. A lithium-ion battery is fabricated using the negative electrode materials obtained in Comparative Examples 1-2 and Examples 1-13 as active materials. The fabrication procedure is as follows.

[0137] Binder preparation: Polyacrylic acid and sodium carboxymethylcellulose were uniformly mixed in a 1:1 mass ratio, a certain amount of pure water was added, and the mixture was magnetically stirred for 6 to 12 hours. Silicon composite material and conductive agent were added to the binder so that the mass ratio of silicon composite material, conductive agent, and binder was 70:15:15, and the mixture was magnetically stirred for 6 to 12 hours to obtain a slurry. For the manufacture of electrode sheets, the slurry was uniformly applied to copper foil, dried, sliced, and dried to obtain silicon composite electrode sheets.

[0138] A buckle battery is assembled and its electrochemical performance is tested. The battery case used is a CR2032, the electrode pair is a metallic lithium sheet, and 1M LiPF6 is the electrolyte. However, Examples 1-13 are denoted as S1-13, and Comparative Examples 1-2 are denoted as D1-2.

[0139] [Table 1]

[0140] [Table 2]

[0141] The data in Tables 1 and 2, which show the test results of the comparative examples and examples, indicate that the anode material of the present application contains a silicon matrix and porous carbon, with at least some of the silicon matrix distributed within the pores of the porous carbon. The ratio Z of the vibrational peak area of ​​SiH2 bonds to the vibrational peak area of ​​SiH bonds in the anode material is 0.01 to 5.0, indicating that the present application demonstrates sufficient silane decomposition during the manufacturing process of the anode material. As a result, much of the silicon matrix in the anode material exists as amorphous silicon with SiH bonds, which mitigates the volume expansion of the anode material, reduces swelling of electrode sheets manufactured from the anode material, and improves the cycle performance and magnification performance of the anode material.

[0142] Under equivalent conditions, I D / I G A larger value indicates that silane is more likely to deposit on the carbon material, but if the amount of silicon deposited is too large, the cycle performance and magnification performance of the anode material will decrease. In Examples 1 to 3, as the heat treatment temperature increases in step (1), I D / I G A gradual decrease in the ratio is observed. In this application, the amount of silicon matrix deposited in the negative electrode material of Example 2 is appropriate, optimizing the initial efficiency and expansion performance of the negative electrode material.

[0143] The silane decomposition temperature in this application significantly affects the performance of the anode material. Examples 2, 4, 5, 6, 7, 8, 9, and 10 show that as the silane decomposition temperature increases, the Z value decreases, indicating increasingly sufficient silane decomposition and improved conversion rate of silane decomposition. However, if the silane decomposition temperature is too high, it can lead to a transition of amorphous silicon to crystalline silicon. Therefore, when the temperature at which silane decomposes into a silicon matrix is ​​550°C, the anode material can simultaneously obtain good cycle performance and expansion performance.

[0144] In Examples 4 and 11, under constant temperature conditions and equivalent silane deposition conditions, the degree of silane decomposition does not change significantly with increasing reaction time, indicating that whether silane decomposition is complete or not mainly depends on the temperature of silane decomposition.

[0145] In the negative electrode material prepared in Comparative Example 1, the silane decomposition temperature was low, the conversion rate of silane decomposition was low, and the silicon load in the porous matrix was low. In the silicon matrix where the silane was not sufficiently decomposed, it existed in the form of SiH2 bonds, SiH3 bonds, and SiH bonds, and moreover, the amount of SiH bonds was low, resulting in Z not being in the range of 0.01 to 5.0. This led to a significant decrease in the structural stability of the negative electrode material, and further resulted in inferior cycle performance, capacity, and magnification performance of the negative electrode material.

[0146] In the case of the anode material prepared in Comparative Example 2, the silane decomposition temperature was too high, resulting in the formation of polycrystalline silicon through silane decomposition. The volume expansion of the polycrystalline silicon was large, leading to poor cycle performance and expansion performance of the anode material.

[0147] The foregoing describes only preferred embodiments of the present application and is not intended to limit it. Various modifications and changes are possible for those skilled in the art. All modifications, equivalent substitutions, and improvements made within the scope of the protection of the present application should also be included within the scope of the protection of the present application.

Claims

1. It is a negative electrode material, The aforementioned negative electrode material includes an active material, The active material comprises a porous matrix and a silicon matrix. At least a portion of the silicon matrix is ​​distributed within the pores of the porous matrix, The infrared spectrum obtained by measuring the negative electrode material using an infrared spectrometer showed a wavenumber of 2090 cm⁻¹. -1 SiH 2 The coupling stretching vibration peak and wavenumber are 2000 cm. -1 There is a stretching vibration peak in the SiH bond. The aforementioned Si H 2 A negative electrode material characterized in that the ratio Z of the vibration peak area of ​​the bond to the vibration peak area of ​​the SiH bond is 0.01 to 5.

0.

2. The negative electrode material according to claim 1, characterized in that the value of the ratio Z is 0.05 to 3.

0.

3. The anode material according to claim 1, characterized in that the porosity after the silicon matrix is ​​removed in the anode material is 30% to 70%.

4. The negative electrode material according to claim 1, characterized in that the average pore size after the silicon matrix has been removed in the negative electrode material is 0.2 nm to 10 nm.

5. The negative electrode material according to claim 1, characterized in that the average particle size of the silicon matrix is ​​1 nm to 10 nm.

6. The negative electrode material according to claim 1, characterized in that the proportion of the silicon matrix mass in the negative electrode material is 5% to 90%.

7. The negative electrode material according to claim 1, characterized in that at least a portion of the silicon matrix is ​​distributed on the surface of the porous matrix.

8. The negative electrode material further includes a coating layer provided on at least a portion of the surface of the active material, The anode material according to claim 1, characterized in that the anode material includes at least one of the following features (1) to (2). (1) The coating layer contains at least one of the following: carbon material, metal oxide, and metal sulfide (2) The thickness of the coating layer is 5 nm to 500 nm.

9. The negative electrode material according to claim 8, characterized in that the negative electrode material includes at least one of the following features (1) to (3). （１） The aforementioned coating layer contains a carbon material, The carbon material includes at least one of graphene, soft carbon, hard carbon, and conductive polymer. （２） The coating layer contains a metal oxide, The aforementioned metal oxide includes at least one of titanium oxide, aluminum oxide, lithium oxide, cobalt oxide, and vanadium oxide. （３） The coating layer contains a metal sulfide, The aforementioned metal sulfide includes at least one of tin sulfide, molybdenum sulfide, titanium sulfide, iron sulfide, and copper sulfide.

10. The anode material according to claim 1, characterized in that the anode material includes at least one of the following features (1) to (3). (1) The median particle size D50 of the negative electrode material is 5 μm to 10 μm. (2) The minimum particle size D00 of the negative electrode material is 1 μm to 3 μm. (3) The D90 of the negative electrode material is 14 μm to 25 μm.

11. In the Raman spectrum diagram obtained by Raman spectroscopy using a measurement light source with a wavelength of 633 nm for the negative electrode material, the negative electrode material has a characteristic peak I at a position of 1310 cm -1 to 1350 cm -1 , and a characteristic peak I at a position of 1580 cm D to 1620 cm -1 . The negative electrode material according to claim 1 is characterized in that I -1 / I G is shown to be 1.6 to 2.5.​​​​

12. The specific surface area of ​​the negative electrode material is 1.0 m². 2 / g to 10.0m 2 The negative electrode material according to claim 1, characterized in that it is / g.

13. The negative electrode material according to claim 1, characterized in that the powder conductivity of the negative electrode material is 0.1 S / cm to 10.0 S / cm.

14. The anode material according to claim 1, characterized in that the porosity of the anode material is 0.01% to 10%.

15. A lithium-ion battery characterized by containing the negative electrode material described in any one of claims 1 to 14.

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